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Sample records for adsorption distribution metabolism

  1. Demonstration of Metabolic Heat Regenerated Temperature Swing Adsorption Technology

    NASA Technical Reports Server (NTRS)

    Paul, Heather; Iacomini, Christine; Powers, Aaron; Dunham, Jonah; Straub-Lopez, Katie; Anerson, Grant; MacCallum, Taber

    2007-01-01

    Patent-pending Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is currently being investigated for removal and rejection of CO2 and heat from a Portable Life Support System (PLSS) to a Martian environment. The metabolically-produced CO2 present in the vent loop gas is collected using a CO2 selective adsorbent that has been cooled via a heat exchanger to near CO2 sublimation temperatures (approx.195K) with liquid CO2 obtained from Martian resources. Once the adsorbent is fully loaded, fresh warm, moist vent loop (approx.300K) is used to heat the adsorbent via another heat exchanger. The adsorbent will then reject the collected CO2 to the Martian ambient. Two beds are used to achieve continuous CO2 removal by cycling between the cold and warm conditions for adsorbent loading and regeneration, respectively. Small experiments have already been completed to show that an adsorbent can be cycled between these PLSS operating conditions to provide adequate conditions for CO2 removal from a simulated vent loop. One of the remaining technical challenges is extracting enough heat from the vent loop to warm the adsorbent in an appreciable time frame to meet the required adsorb/desorb cycle. The other key technical aspect of the technology is employing liquid CO2 to achieve the appropriate cooling. A technology demonstrator has been designed, built and tested to investigate the feasibility of 1) warming the adsorbent using the moist vent loop, 2) cooling the adsorbent using liquid CO2, and 3) using these two methods in conjunction to successfully remove CO2 from a vent loop and reject it to Mars ambient. Both analytical and numerical methods were used to perform design calculations and trades. The demonstrator was built and tested. The design analysis and testing results are presented along with recommendations for future development required to increase the maturity of the technology.

  2. Simulated Lunar Testing of Metabolic Heat Regenerated Temperature Swing Adsorption

    NASA Technical Reports Server (NTRS)

    Padilla, Sebastian A.; Bower, Chad E.; Iacomini, Christie S.; Paul, Heather L.

    2012-01-01

    Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is being developed for thermal and carbon dioxide (CO2) control for a Portable Life Support System (PLSS), as well as water recycling. An Engineering Development Unit (EDU) of the MTSA Subassembly (MTSAS) was designed and assembled for optimized Martian operations, but also meets system requirements for lunar operations. For lunar operations the MTSA sorption cycle is driven via a vacuum swing between suit ventilation loop pressure and lunar vacuum. The focus of this effort was testing in a simulated lunar environment. This environment was simulated in Paragon's EHF vacuum chamber. The objective of the testing was to evaluate the full cycle performance of the MTSA Subassembly EDU, and to assess CO2 loading and pressure drop of the wash coated aluminum reticulated foam sorbent bed. Lunar environment testing proved out the feasibility of pure vacuum swing operation, making MTSA a technology that can be tested and used on the Moon prior to going to Mars. Testing demonstrated better than expected CO2 Nomenclature loading on the sorbent and nearly replicates the equilibrium data from the sorbent manufacturer. This exceeded any of the previous sorbent loading tests performed by Paragon. Subsequently, the increased performance of the sorbent bed design indicates future designs will require less mass and volume than the current EDU rendering MTSA as very competitive for Martian PLSS applications.

  3. The impact of metabolic state on Cd adsorption onto bacterial cells

    USGS Publications Warehouse

    Johnson, K.J.; Ams, D.A.; Wedel, A.N.; Szymanowski, J.E.S.; Weber, D.L.; Schneegurt, M.A.; Fein, J.B.

    2007-01-01

    This study examines the effect of bacterial metabolism on the adsorption of Cd onto Gram-positive and Gram-negative bacterial cells. Metabolically active Gram-positive cells adsorbed significantly less Cd than non-metabolizing cells. Gram-negative cells, however, showed no systematic difference in Cd adsorption between metabolizing and non-metabolizing cells. The effect of metabolism on Cd adsorption to Gram-positive cells was likely due to an influx of protons in and around the cell wall from the metabolic proton motive force, promoting competition between Cd and protons for adsorption sites on the cell wall. The relative lack of a metabolic effect on Cd adsorption onto Gram-negative compared to Gram-positive cells suggests that Cd binding in Gram-negative cells is focused in a region of the cell wall that is not reached, or is unaffected by this proton flux. Thermodynamic modeling was used to estimate that proton pumping causes the pH in the cell wall of metabolizing Gram-positive bacteria to decrease from the bulk solution value of 7.0 to approximately 5.7. ?? 2007 The Authors.

  4. Optimal smoothing of site-energy distributions from adsorption isotherms

    SciTech Connect

    Brown, L.F.; Travis, B.J.

    1983-01-01

    The equation for the adsorption isotherm on a heterogeneous surface is a Fredholm integral equation. In solving it for the site-energy distribution (SED), some sort of smoothing must be carried out. The optimal amount of smoothing will give the most information that is possible without introducing nonexistent structure into the SED. Recently, Butler, Reeds, and Dawson proposed a criterion (the BRD criterion) for choosing the optimal smoothing parameter when using regularization to solve Fredholm equations. The BRD criterion is tested for its suitability in obtaining optimal SED's. This criterion is found to be too conservative. While using it never introduces nonexistent structure into the SED, significant information is often lost. At present, no simple criterion for choosing the optimal smoothing parameter exists, and a modeling approach is recommended.

  5. Xe adsorption site distributions on Pt(111), Pt(221) and Pt(531)

    NASA Astrophysics Data System (ADS)

    Gellman, Andrew J.; Baker, L.; Holsclaw, B. S.

    2016-04-01

    The ideal structures of the Pt(111), Pt(221) and Pt(531) surfaces expose adsorption sites that can be qualitatively described as terrace sites on Pt(111), both step and terrace sites on Pt(221), and kink sites on Pt(531). The real surface structures of these surfaces can be complicated by imperfections such as misorientation, reconstruction and thermal roughening, all of which will influence their distributions of adsorption sites. Xe adsorption sites on the Pt(111), Pt(221) and Pt(531) surfaces have been probed using both photoemission of adsorbed Xe (PAX) and temperature programmed desorption (TPD) of Xe. Both PAX and Xe TPD are sensitive to the adsorption sites of the Xe and serve as complementary means of assessing the distributions of adsorption sites on these three Pt surfaces. The adsorption of Xe is sufficiently sensitive to detect the presence of residual steps on the Pt(111) surface at a density of ~ 1.5% step atoms per Pt atom. On the Pt(221) surface, PAX and Xe TPD reveal adsorption at both terrace and step sites simultaneously. Although the ideal structure of the Pt(531) surface has no well-defined steps or terraces, Xe adsorption indicates that its adsorption sites are best described as a distribution of both step and kink sites with roughly twice as many steps sites as kinks.

  6. Adsorption-uptake-metabolism kinetic model on the removal of BDE-47 by a Chlorella isolate.

    PubMed

    Deng, Dan; Tam, Nora F Y

    2016-05-01

    Polybrominated diphenyl ethers (PBDEs) are persistent and toxic organic pollutants, causing hazardous to ecosystems and human health but are difficult to remove from contaminated environments. The mechanism and kinetics of a Chlorella isolate to remove BDE-47 were investigated. This species isolated from the influent of wastewater treatment plants in Hong Kong was PBDE tolerant. More than 80% of BDE-47 was removed in short- and long-term experiments lasting 1 h and 7 days, respectively. The dominant removal process was adsorption on cell surfaces, with 73% of the spiked BDE-47 removed within five minutes of exposure. As the exposure prolonged, the adsorption became saturated. BDE-47 on cell surfaces was then gradually taken up into cells. At the end of the 7-day exposure, 17% of the spiked BDE-47 was within cells, while 27% was metabolized. Four metabolites, including BDE-28, 6-OH- and 5-OH-BDE-47, and 6-MeO-BDE-47, were produced from the debromination, hydroxylation and methoxylation of BDE-47. The removal kinetics of BDE-47 by freshwater microalgae could be explained by the multi-compartmental adsorption-uptake-metabolism model developed in this study. PMID:26854698

  7. Influence of pore size distribution on the adsorption of phenol on PET-based activated carbons.

    PubMed

    Lorenc-Grabowska, Ewa; Diez, María A; Gryglewicz, Grazyna

    2016-05-01

    The role of pore size distribution in the adsorption of phenol in aqueous solutions on polyethylene terephthalate (PET)-based activated carbons (ACs) has been analyzed. The ACs were prepared from PET and mixtures of PET with coal-tar pitch (CTP) by means of carbonization and subsequent steam and carbon dioxide activation at 850 and 950 °C, respectively. The resultant ACs were characterized on the basis of similarities in their surface chemical features and differences in their micropore size distributions. The adsorption of phenol was carried out in static conditions at ambient temperature. The pseudo-second order kinetic model and Langmuir model were found to fit the experimental data very well. The different adsorption capacities of the ACs towards phenol were attributed to differences in their micropore size distributions. Adsorption capacity was favoured by the volume of pores with a size smaller than 1.4 nm; but restricted by pores smaller than 0.8 nm. PMID:26890386

  8. Pore size distribution analysis of activated carbons prepared from coconut shell using methane adsorption data

    NASA Astrophysics Data System (ADS)

    Ahmadpour, A.; Okhovat, A.; Darabi Mahboub, M. J.

    2013-06-01

    The application of Stoeckli theory to determine pore size distribution (PSD) of activated carbons using high pressure methane adsorption data is explored. Coconut shell was used as a raw material for the preparation of 16 different activated carbon samples. Four samples with higher methane adsorption were selected and nitrogen adsorption on these adsorbents was also investigated. Some differences are found between the PSD obtained from the analysis of nitrogen adsorption isotherms and their PSD resulting from the same analysis using methane adsorption data. It is suggested that these differences may arise from the specific interactions between nitrogen molecules and activated carbon surfaces; therefore caution is required in the interpretation of PSD obtained from the nitrogen isotherm data.

  9. Testing, Modeling and System Impact of Metabolic Heat Regenerated Temperature Swing Adsorption

    NASA Technical Reports Server (NTRS)

    Lacomini, Christine S.; Powers, Aaron; Lewis, Matthew; Linrud, Christopher; Waguespack, Glenn; Conger, Bruce; Paul, Heather L.

    2008-01-01

    Metabolic heat regenerated temperature swing adsorption (MTSA) technology is being developed for removal and rejection of carbon dioxide (CO2) and heat from a portable life support system (PLSS) to the Martian environment. Previously, hardware was built and tested to demonstrate using heat from simulated, dry ventilation loop gas to affect the temperature swing required to regenerate an adsorbent used for CO2 removal. New testing has been performed using a moist, simulated ventilation loop gas to demonstrate the effects of water condensing and freezing in the heat exchanger during adsorbent regeneration. In addition, thermal models of the adsorbent during regeneration were modified and calibrated with test data to capture the effect of the CO2 heat of desorption. Finally, MTSA impact on PLSS design was evaluated by performing thermal balances assuming a specific PLSS architecture. Results using NASA s Extravehicular Activity System Sizing Analysis Tool (EVAS_SAT), a PLSS system evaluation tool, are presented.

  10. A surface structural approach to ion adsorption: The charge distribution (CD) model

    SciTech Connect

    Hiemstra, T.; Van Riemsdijk, W.H.

    1996-05-10

    Cation and anion adsorption at the solid/solution interface of metal hydroxides plays an important role in several fields of chemistry, including colloid and interface chemistry, soil chemistry and geochemistry, aquatic chemistry, environmental chemistry, catalysis, and chemical engineering. An ion adsorption model for metal hydroxides has been developed which deals with the observation that in the case of inner sphere complex formation only part of the surface complex is incorporated into the surface by a ligand exchange reaction while the other part is located in the Stern layer. The charge distribution (CD) concept of Pauling, used previously in the multi site complexation (MUSIC) model approach, is extended to account for adsorbed surface complexes. In the new model, surface complexes are not treated as point charges, but are considered as having a spatial distribution of charge in the interfacial region. The new CD model can describe within a single conceptual framework all important experimental adsorption phenomena, taking into account the chemical composition of the crystal surface. The CD model has been applied to one of the most difficult and challenging ion adsorption phenomena, i.e., PO{sub 4} adsorption on goethite, and successfully describes simultaneously the basic charging behavior of goethite, the concentration, pH, and salt dependency of adsorption, the shifts in the zeta potentials and isoelectric point (IEP), and the OH/P exchange ratio. This is all achieved within the constraint that the experimental surface speciation found from in situ IR spectroscopy is also described satisfactorily.

  11. Metabolic Adaptation Processes That Converge to Optimal Biomass Flux Distributions

    PubMed Central

    Altafini, Claudio; Facchetti, Giuseppe

    2015-01-01

    In simple organisms like E.coli, the metabolic response to an external perturbation passes through a transient phase in which the activation of a number of latent pathways can guarantee survival at the expenses of growth. Growth is gradually recovered as the organism adapts to the new condition. This adaptation can be modeled as a process of repeated metabolic adjustments obtained through the resilencings of the non-essential metabolic reactions, using growth rate as selection probability for the phenotypes obtained. The resulting metabolic adaptation process tends naturally to steer the metabolic fluxes towards high growth phenotypes. Quite remarkably, when applied to the central carbon metabolism of E.coli, it follows that nearly all flux distributions converge to the flux vector representing optimal growth, i.e., the solution of the biomass optimization problem turns out to be the dominant attractor of the metabolic adaptation process. PMID:26340476

  12. Distribution of trace impurities of metals during their adsorption from solutions of phosphoric acid

    SciTech Connect

    Toranov, A.N.; Evseeva, N.K.; Kremenskaya, I.N.

    1986-09-01

    The phase distribution of trace impurities of metals between solutions of phosphoric acid and a polymer adsorbent based on a copolymer of styrene with divinylbenzene, impregnated with di-2-ethylhexyldithiophosphoric acid, was investigated. The influence of the composition of the aqueous and solid phases on the distribution coefficients of trace impurities of metals is discussed. It was shown that the coefficients of interfacial distribution in the case of adsorption by an impregnated adsorbent is higher than in the case of liquid extraction.

  13. Site energy distribution analysis of Cu (Ⅱ) adsorption on sediments and residues by sequential extraction method.

    PubMed

    Jin, Qiang; Yang, Yan; Dong, Xianbin; Fang, Jimin

    2016-01-01

    Many models (e.g., Langmuir model, Freundlich model and surface complexation model) have been successfully used to explain the mechanism of metal ion adsorption on the pure mineral materials. These materials usually have a homogeneous surface where all sites have the same adsorption energies. However, it's hardly appropriate for such models to describe the adsorption on heterogeneous surfaces (e.g., sediment surface), site energy distribution analysis can be to. In the present study, the site energy distribution analysis was used to describe the surface properties and adsorption behavior of the non-residual and residual components extracted from the natural aquatic sediment samples. The residues were prepared "in-situ" by using the sequential extraction procedure. The present study is intended to investigate the roles of different components and the change of site energy distribution at different temperatures of the sediment samples in controlling Cu (Ⅱ) adsorption. The results of the site energy distribution analysis indicated firstly, that the sorption sites of iron/manganese hydrous oxides (IMHO) and organic matter (OM) have higher energy. Secondly, light fraction (LF) and carbonates have little influence on site energy distribution. Finally, there was increase in site energies with the increase of temperature. Specially, low temperature (5 °C) significantly influenced the site energies of IMHO and OM, and also had obvious effect on the energy distribution of the sediments after removing target components. The site energy distribution analysis proved to be a useful method for us to further understand the energetic characteristics of sediment in comparison with those previously obtained. PMID:26552542

  14. The distribution and adsorption behavior of aliphatic amines in marine and lacustrine sediments

    SciTech Connect

    Wang, Xuchen; Lee, C. )

    1990-10-01

    The methylated amines - monomethyl-, dimethyl-, and trimethyl amine (MMA, DMA, TMA) - are commonly found in aquatic environments, apparently as a result of decomposition processes. Adsorption of these amines to clay minerals and organic matter significantly influences their distribution in sediments. Laboratory measurements using {sup 14}C-radiolabelled amines and application of a linear partitioning model resulted in calculated adsorption coefficients of 2.4-4.7 (MMA), 3.3 (DMA), and 3.3-4.1 (TMA). Further studies showed that adsorption of amines is influenced by salinity of the porewaters, and clay mineral and organic matter content of the sediment solid phase. Concentrations of monomethyl- and dimethyl amine were measured in the porewaters and the solid phase of sediment samples collected from Flax Pond and Lake Ronkonkoma (NY), Long Island Sound, and the coastal Peru upwelling area. These two amines were present in all sediments investigated. A clear seasonal increase in the solid-phase concentration of MMA and DMA in Flax Pond sediments was likely related to the annual senescence of salt marsh grasses, either directly as a source of these compounds or indirectly by providing additional exchange capacity to the sediments. The distribution of amines in the solid and dissolved phases observed in all sediments investigated suggests that the distribution of these compounds results from a balance among production, decomposition, and adsorption processes.

  15. Effect of surface charge distribution on the adsorption orientation of proteins to lipid monolayers.

    PubMed

    Tiemeyer, Sebastian; Paulus, Michael; Tolan, Metin

    2010-09-01

    The adsorption orientation of the proteins lysozyme and ribonuclease A (RNase A) to a neutral 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and a negatively charged stearic acid lipid film was investigated by means of X-ray reflectivity. Both proteins adsorbed to the negatively charged lipid monolayer, whereas at the neutral monolayer, no adsorption was observed. For acquiring comprehensive information on the proteins' adsorption, X-ray reflectivity data were combined with electron densities obtained from crystallographic data. With this method, it is possible to determine the orientation of adsorbed proteins in solution underneath lipid monolayers. While RNase A specifically coupled with its positively charged active site to the negatively charged lipid monolayer, lysozyme prefers an orientation with its long axis parallel to the Langmuir film. In comparison to the electrostatic maps of the proteins, our results can be explained by the discriminative surface charge distribution of lysozyme and RNase A. PMID:20707324

  16. Simulated Lunar Testing of Metabolic Heat Regenerated Temperature Swing Adsorption Technology

    NASA Technical Reports Server (NTRS)

    Padilla, Sebastian A.; Bower, Chad; Iacomini, Christie S.; Paul, H.

    2011-01-01

    Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is being developed for thermal and carbon dioxide (CO2) control for a Portable Life Support System (PLSS), as well as water recycling. An Engineering Development Unit (EDU) of the MTSA subassembly was designed and assembled for optimized Martian operations, but also meets system requirements for lunar operations. For lunar operations the MTSA sorption cycle is driven via a vacuum swing between suit ventilation loop pressure and lunar vacuum. The focus of this effort is operations and testing in a simulated lunar environment. This environment was simulated in Paragon s EHF vacuum chamber. The objective of this testing was to evaluate the full cycle performance of the MTSA Subassembly EDU, and to assess CO2 loading and pressure drop of the wash coated aluminum reticulated foam sorbent bed. The lunar testing proved out the feasibility of pure vacuum swing operation, making MTSA a technology that can be tested and used on the Moon prior to going to Mars. Testing demonstrated better than expected CO2 loading on the sorbent and nearly replicates the equilibrium data from the sorbent manufacturer. This had not been achieved in any of the previous sorbent loading tests performed by Paragon. Subsequently, the increased performance of the sorbent bed design indicates future designs will require less mass and volume than the current EDU rendering MTSA as very competitive for Martian PLSS applications.

  17. Pore size distribution and supercritical hydrogen adsorption in activated carbon fibers

    NASA Astrophysics Data System (ADS)

    Purewal, J. J.; Kabbour, H.; Vajo, J. J.; Ahn, C. C.; Fultz, B.

    2009-05-01

    Pore size distributions (PSD) and supercritical H2 isotherms have been measured for two activated carbon fiber (ACF) samples. The surface area and the PSD both depend on the degree of activation to which the ACF has been exposed. The low-surface-area ACF has a narrow PSD centered at 0.5 nm, while the high-surface-area ACF has a broad distribution of pore widths between 0.5 and 2 nm. The H2 adsorption enthalpy in the zero-coverage limit depends on the relative abundance of the smallest pores relative to the larger pores. Measurements of the H2 isosteric adsorption enthalpy indicate the presence of energy heterogeneity in both ACF samples. Additional measurements on a microporous, coconut-derived activated carbon are presented for reference.

  18. Pore size distribution and supercritical hydrogen adsorption in activated carbon fibers.

    PubMed

    Purewal, J J; Kabbour, H; Vajo, J J; Ahn, C C; Fultz, B

    2009-05-20

    Pore size distributions (PSD) and supercritical H2 isotherms have been measured for two activated carbon fiber (ACF) samples. The surface area and the PSD both depend on the degree of activation to which the ACF has been exposed. The low-surface-area ACF has a narrow PSD centered at 0.5 nm, while the high-surface-area ACF has a broad distribution of pore widths between 0.5 and 2 nm. The H2 adsorption enthalpy in the zero-coverage limit depends on the relative abundance of the smallest pores relative to the larger pores. Measurements of the H2 isosteric adsorption enthalpy indicate the presence of energy heterogeneity in both ACF samples. Additional measurements on a microporous, coconut-derived activated carbon are presented for reference. PMID:19420660

  19. Adsorption and Distribution of Fluorescent Solutes near the Articular Surface of Mechanically Injured Cartilage

    PubMed Central

    Decker, Sarah G.A.; Moeini, Mohammad; Chin, Hooi Chuan; Rosenzweig, Derek H.; Quinn, Thomas M.

    2013-01-01

    The development of cartilage-specific imaging agents supports the improvement of tissue assessment by minimally invasive means. Techniques for highlighting cartilage surface damage in clinical images could provide for sensitive indications of posttraumatic injury and early stage osteoarthritis. Previous studies in our laboratory have demonstrated that fluorescent solutes interact with cartilage surfaces strongly enough to affect measurement of their partition coefficients within the tissue bulk. In this study, these findings were extended by examining solute adsorption and distribution near the articular surface of mechanically injured cartilage. Using viable cartilage explants injured by an established protocol, solute distributions near the articular surface of three commonly used fluorophores (fluorescein isothiocyanate (FITC), tetramethylrhodamine isothiocyanate (TRITC), and carboxytetramethylrhodamine (TAMRA)) were observed after absorption and subsequent desorption to assess solute-specific matrix interactions and reversibility. Both absorption and desorption processes demonstrated a trend of significantly less solute adsorption at surfaces of fissures compared to adjacent intact surfaces of damaged explants or surfaces of uninjured explants. After adsorption, normalized mean surface intensities of fissured surfaces of injured explants were 6%, 40%, and 32% for FITC, TRITC, and TAMRA, respectively, compared to uninjured surfaces. Similar values were found for sliced explants and after a desorption process. After desorption, a trend of increased solute adsorption at the site of intact damaged surfaces was noted (316% and 238% for injured and sliced explants exposed to FITC). Surface adsorption of solute was strongest for FITC and weakest for TAMRA; no solutes negatively affected cell viability. Results support the development of imaging agents that highlight distinct differences between fissured and intact cartilage surfaces. PMID:24268155

  20. Protein Adsorption Patterns and Analysis on IV Nanoemulsions—The Key Factor Determining the Organ Distribution

    PubMed Central

    Keck, Cornelia M.; Jansch, Mirko; Müller, Rainer H.

    2012-01-01

    Intravenous nanoemulsions have been on the market for parenteral nutrition since the 1950s; meanwhile, they have also been used successfully for IV drug delivery. To be well tolerable, the emulsions should avoid uptake by the MPS cells of the body; for drug delivery, they should be target-specific. The organ distribution is determined by the proteins adsorbing them after injection from the blood (protein adsorption pattern), typically analyzed by two-dimensional polyacrylamide gel electrophoresis, 2-D PAGE. The article reviews the 2-D PAGE method, the analytical problems to be faced and the knowledge available on how the composition of emulsions affects the protein adsorption patterns, e.g., the composition of the oil phase, stabilizer layer and drug incorporation into the interface or oil core. Data were re-evaluated and compared, and the implications for the in vivo distribution are discussed. Major results are that the interfacial composition of the stabilizer layer is the main determining factor and that this composition can be modulated by simple processes. Drug incorporation affects the pattern depending on the localization of the drug (oil core versus interface). The data situation regarding in vivo effects is very limited; mainly, it has to be referred to in the in vivo data of polymeric nanoparticles. As a conclusion, determination of the protein adsorption patterns can accelerate IV nanoemulsion formulation development regarding optimized organ distribution and related pharmacokinetics. PMID:24300396

  1. System Modeling of Metabolic Heat Regenerated Temperature Swing Adsorption (MTSA) Subassembly for Prototype Design

    NASA Technical Reports Server (NTRS)

    Bower, Chad; Padilla, Sebastian; Iacomini, Christie; Paul, Heather L.

    2009-01-01

    This paper describes modeling methods for the three core components of a Metabolic heat regenerated Temperature Swing Adsorption (MTSA) subassembly: the sorbent bed, a sublimation (cooling) heat exchanger (SHX), and a condensing icing (warming) heat exchanger (CIHX). The primary function of the MTSA, removing carbon dioxide from a ventilation loop, is performed via the sorbent bed. The CIHX is used to heat the sorbent bed for desorption and to remove moisture from the ventilation loop while the SHX is alternately employed to cool the sorbent bed via sublimation of a spray of water at low pressure to prepare the reconditioned bed for the next cycle. This paper describes a system level model of the MTSA as developed in Thermal Desktop and SINDA/FLUINT including assumptions on geometry and physical phenomena, modeling methodology and relevant pa ra mete rizatio ns. Several areas of particular modeling interest are discussed. In the sorbent bed, capture of the translating CO2 saturation front and associated local energy and mass balance in both adsorbing and desorbing modes is covered. The CIHX poses particular challenges for modeling in SINDA/FLUINT as accounting for solids states in fluid submodels are not a native capability. Methods for capturing phase change and latent heat of ice as well as the transport properties across a layer of low density accreted frost are developed. This extended modeling capacity is applicable to temperatures greater than 258 K. To extend applicability to the minimum device temperature of 235 K, a method for a mapped transformation of temperatures from below the limit temperatures to some value above is given along with descriptions for associated material property transformations and the resulting impacts to total heat and mass transfer. Similar considerations are shown for the SHX along with assumptions for flow mechanics and resulting model methods for sublimation in a flow.

  2. Modeling Of Metabolic Heat Regenerated Temperature Swing Adsorption (MTSA) Subassembly For Prototype Design

    NASA Technical Reports Server (NTRS)

    Bower, Chad E.; Padilla, Sebastian A.; Iacomini, Christie S.; Paul, Heather L.

    2010-01-01

    This paper describes modeling methods for the three core components of a Metabolic heat regenerated Temperature Swing Adsorption (MTSA) subassembly: a sorbent bed, a sublimation (cooling) heat exchanger (SHX), and a condensing icing (warming) heat exchanger (CIHX). The primary function of the MTSA, removing carbon dioxide from a space suit Portable Life Support System (PLSS) ventilation loop, is performed via the sorbent bed. The CIHX is used to heat the sorbent bed for desorption and to remove moisture from the ventilation loop while the SHX is alternately employed to cool the sorbent bed via sublimation of a spray of water at low pressure to prepare the reconditioned bed for the next cycle. This paper describes subsystem heat a mass transfer modeling methodologies relevant to the description of the MTSA subassembly in Thermal Desktop and SINDA/FLUINT. Several areas of particular modeling interest are discussed. In the sorbent bed, capture of the translating carbon dioxide (CO2) front and associated local energy and mass balance in both adsorbing and desorbing modes is covered. The CIHX poses particular challenges for modeling in SINDA/FLUINT as accounting for solids states in fluid submodels are not a native capability. Methods for capturing phase change and latent heat of ice as well as the transport properties across a layer of low density accreted frost are developed. This extended modeling capacity is applicable to temperatures greater than 258 K. To extend applicability to the minimum device temperature of 235 K, a method for a mapped transformation of temperatures from below the limit temperatures to some value above is given along with descriptions for associated material property transformations and the resulting impacts to total heat and mass transfer. Similar considerations are given for the SHX along with functional relationships for areal sublimation rates as limited by flow mechanics in t1he outlet duct.

  3. Multiscale characterization of pore size distributions using mercury porosimetry and nitrogen adsorption

    NASA Astrophysics Data System (ADS)

    Paz-Ferreiro, J.; Tarquis, A. M.; Miranda, J. G. V.; Vidal Vázquez, E.

    2009-04-01

    The soil pore space is a continuum extremely variable in size, including structures smaller than nanometres and as large as macropores or cracks with millimetres or even centimetres size. Pore size distributions (PSDs) affects important soil functions, such as those related with transmission and storage of water, and root growth. Direct and indirect measurements of PSDs are becoming increasingly used to characterize soil structure. Mercury injection porosimetry and nitrogen adsorption isotherms are techniques commonly employed for assessing equivalent pore size diameters in the range from about 50 nm to 100 m and 2 to 500 nm, respectively. The multifractal formalism was used to describe Hg injection curves and N2 adsorption isotherms from two series of a Mollisol cultivated under no tillage and minimum tillage. Soil samples were taken from 0-10, 10-20 and 20-30 cm depths in two experimental fields located in the north of Buenos Aires and South of Santa Fe provinces, Argentina. All the data sets analyzed from the two studied soil attributes showed remarkably good scaling trends as assessed by singularity spectrum and generalized dimension spectrum. Both, experimental Hg injection curves and N2 adsorption isotherms could be fitted reasonably well with multifractal models. A wide variety of singularity and generalized dimension spectra was found for the variables. The capacity dimensions, D0, for both Hg injection and N2 adsorption data were not significantly different from the Euclidean dimension. However, the entropy dimension, D1, and correlation dimension, D2, obtained from mercury injection and nitrogen adsorption data showed significant differences. So, D1 values were on average 0.868 and varied from 0.787 to 0.925 for Hg intrusion curves. Entropy dimension, D1, values for N2 adsorption isotherms were on average 0.582 significantly lower than those obtained when using the former technique. Twenty-three out of twenty-four N2 isotherms had D1 values in a

  4. Lipid metabolizing enzyme activities modulated by phospholipid substrate lateral distribution.

    PubMed

    Salinas, Dino G; Reyes, Juan G; De la Fuente, Milton

    2011-09-01

    Biological membranes contain many domains enriched in phospholipid lipids and there is not yet clear explanation about how these domains can control the activity of phospholipid metabolizing enzymes. Here we used the surface dilution kinetic theory to derive general equations describing how complex substrate distributions affect the activity of enzymes following either the phospholipid binding kinetic model (which assumes that the enzyme molecules directly bind the phospholipid substrate molecules), or the surface-binding kinetic model (which assumes that the enzyme molecules bind to the membrane before binding the phospholipid substrate). Our results strongly suggest that, if the enzyme follows the phospholipid binding kinetic model, any substrate redistribution would increase the enzyme activity over than observed for a homogeneous distribution of substrate. Besides, enzymes following the surface-binding model would be independent of the substrate distribution. Given that the distribution of substrate in a population of micelles (each of them a lipid domain) should follow a Poisson law, we demonstrate that the general equations give an excellent fit to experimental data of lipases acting on micelles, providing reasonable values for kinetic parameters--without invoking special effects such as cooperative phenomena. Our theory will allow a better understanding of the cellular-metabolism control in membranes, as well as a more simple analysis of the mechanisms of membrane acting enzymes. PMID:21108012

  5. Pesticide adsorption in relation to soil properties and soil type distribution in regional scale.

    PubMed

    Kodešová, Radka; Kočárek, Martin; Kodeš, Vít; Drábek, Ondřej; Kozák, Josef; Hejtmánková, Kateřina

    2011-02-15

    Study was focused on the evaluation of pesticide adsorption in soils, as one of the parameters, which are necessary to know when assessing possible groundwater contamination caused by pesticides commonly used in agriculture. Batch sorption tests were performed for 11 selected pesticides and 13 representative soils. The Freundlich equations were used to describe adsorption isotherms. Multiple-linear regressions were used to predict the Freundlich adsorption coefficients from measured soil properties. Resulting functions and a soil map of the Czech Republic were used to generate maps of the coefficient distribution. The multiple linear regressions showed that the K(F) coefficient depended on: (a) combination of OM (organic matter content), pH(KCl) and CEC (cation exchange capacity), or OM, SCS (sorption complex saturation) and salinity (terbuthylazine), (b) combination of OM and pH(KCl), or OM, SCS and salinity (prometryne), (c) combination of OM and pH(KCl), or OM and ρ(z) (metribuzin), (d) combination of OM, CEC and clay content, or clay content, CEC and salinity (hexazinone), (e) combination of OM and pH(KCl), or OM and SCS (metolachlor), (f) OM or combination of OM and CaCO(3) (chlorotoluron), (g) OM (azoxystrobin), (h) combination of OM and pH(KCl) (trifluralin), (i) combination of OM and clay content (fipronil), (j) combination of OM and pH(KCl), or OM, pH(KCl) and CaCO(3) (thiacloprid), (k) combination of OM, pH(KCl) and CEC, or sand content, pH(KCl) and salinity (chlormequat chloride). PMID:21144657

  6. Statistical physics studies of multilayer adsorption isotherm in food materials and pore size distribution

    NASA Astrophysics Data System (ADS)

    Aouaini, F.; Knani, S.; Ben Yahia, M.; Ben Lamine, A.

    2015-08-01

    Water sorption isotherms of foodstuffs are very important in different areas of food science engineering such as for design, modeling and optimization of many processes. The equilibrium moisture content is an important parameter in models used to predict changes in the moisture content of a product during storage. A formulation of multilayer model with two energy levels was based on statistical physics and theoretical considerations. Thanks to the grand canonical ensemble in statistical physics. Some physicochemical parameters related to the adsorption process were introduced in the analytical model expression. The data tabulated in literature of water adsorption at different temperatures on: chickpea seeds, lentil seeds, potato and on green peppers were described applying the most popular models applied in food science. We also extend the study to the newest proposed model. It is concluded that among studied models the proposed model seems to be the best for description of data in the whole range of relative humidity. By using our model, we were able to determine the thermodynamic functions. The measurement of desorption isotherms, in particular a gas over a solid porous, allows access to the distribution of pore size PSD.

  7. Decolorization of acid and basic dyes: understanding the metabolic degradation and cell-induced adsorption/precipitation by Escherichia coli.

    PubMed

    Cerboneschi, Matteo; Corsi, Massimo; Bianchini, Roberto; Bonanni, Marco; Tegli, Stefania

    2015-10-01

    Escherichia coli strain DH5α was successfully employed in the decolorization of commercial anthraquinone and azo dyes, belonging to the general classes of acid or basic dyes. The bacteria showed an aptitude to survive at different pH values on any dye solution tested, and a rapid decolorization was obtained under aerobic conditions for the whole collection of dyes. A deep investigation about the mode of action of E. coli was carried out to demonstrate that dye decolorization mainly occurred via three different pathways, specifically bacterial induced precipitation, cell wall adsorption, and metabolism, whose weight was correlated with the chemical nature of the dye. In the case of basic azo dyes, an unexpected fast decolorization was observed after just 2-h postinoculation under aerobic conditions, suggesting that metabolism was the main mechanism involved in basic azo dye degradation, as unequivocally demonstrated by mass spectrometric analysis. The reductive cleavage of the azo group by E. coli on basic azo dyes was also further demonstrated by the inhibition of decolorization occurring when glucose was added to the dye solution. Moreover, no residual toxicity was found in the E. coli-treated basic azo dye solutions by performing Daphnia magna acute toxicity assays. The results of the present study demonstrated that E. coli can be simply exploited for its natural metabolic pathways, without applying any recombinant technology. The high versatility and adaptability of this bacterium could encourage its involvement in industrial bioremediation of textile and leather dyeing wastewaters. PMID:26062529

  8. Illite spatial distribution controls Cr(VI) adsorption capacity and kinetics

    NASA Astrophysics Data System (ADS)

    WANG, L.; Li, L.

    2013-12-01

    In the natural surbsurface, clays typically are the major sorbing minerals for contaminants. Clays are known to distribute unevenly with low permeability 'clay' zones, which can have significant impacts on the sorption of contaminants. In this work, the effects of illite spatial distribution on Cr(VI) adsorption was examined using column experiments and reactive transport modeling. Three columns were set up with the same volume fraction of illite (10%). The Mixed column has illite evenly distributed within a quartz matrix; the Flow-transverse column has illite distributed in one horizontal zone in the direction that is perpendicular to the main flow; the Flow-parallel column has illite distributed in one cylindrical zone in the direction parallel to the main flow direction. Cr(VI) adsorption experiments were carried out under flow velocities of 0.58, 2.93, and 14.67 m/day. Two-dimensional reactive transport modeling was used to understand the role of illite distribution in determining Cr(VI) sorption capacity and kinetics. The result showed that illite spatial distribution strongly influence Cr(VI) sorption, the extent of which depend on the flow conditions . The Cr(VI) sorption kinectics was influenced by the permeability contrast and the preferential flow paths were taken place in high permeability zones. Under the flow rate of 0.58 m/day, the Cr(VI) adsorption in the Mixed and Flow-transverse columns was very similar, showing similar breakthrough time and sorption capacity. In contrast, an early breakthrough and an extended of Cr(VI) occured in the Flow-parallel column. The 2D reactive transport model showed that the inlet fluids flow through the quartz zone and bypass the lower permeability illite zone. Cr(VI) was first adsorbed on the illite-quartz interface early on and gradually diffuse into the illite zone over time. At the flow velocity of 2.93 m/day, the difference among the three columns was similar to the difference at the flow rate of 0.58 m/day. At

  9. Transient Modeling and Analysis of a Metabolic Heat-Regenerated Temperature Swing Adsorption (MTSA) System for a PLSS

    NASA Technical Reports Server (NTRS)

    Iacomini, Christie; Powers, Aaron; Speight, Garland; Padilla, Sebastian; Paul, Heather L.

    2009-01-01

    A Metabolic heat-regenerated Temperature Swing Adsorption (MTSA) system is being developed for carbon dioxide, water and thermal control in a lunar and martian portable life support system (PLSS). A previous system analysis was performed to evaluate the impact of MTSA on PLSS design. That effort was Mars specific and assumed liquid carbon dioxide (LCO2) coolant made from martian resources. Transient effects were not considered but rather average conditions were used throughout the analysis. This effort takes into further consideration the transient effects inherent in the cycling MTSA system as well as assesses the use of water as coolant. Standard heat transfer, thermodynamic, and heat exchanger methods are presented to conduct the analysis. Assumptions and model verification are discussed. The tool was used to perform various system studies. Coolant selection was explored and takes into account different operational scenarios as the minimum bed temperature is driven by the sublimation temperature of the coolant (water being significantly higher than LCO2). From this, coolant mass is sized coupled with sorbent bed mass because MTSA adsorption performance decreases with increasing sublimation temperature. Reduction in heat exchanger performance and even removal of certain heat exchangers, like a recuperative one between the two sorbent beds, is also investigated. Finally, the coolant flow rate is varied over the cycle to determine if there is a more optimal means of cooling the bed from a mass perspective. Results of these studies and subsequent recommendations for system design are presented.

  10. Distribution and metabolism of four different dimethylated arsenicals in hamsters

    SciTech Connect

    Naranmandura, Hua; Iwata, Katsuya; Suzuki, Kazuo T.; Ogra, Yasumitsu

    2010-05-15

    Arsenic toxicity and distribution are highly dependent on animal species and its chemical species. Recently, thioarsenical has been recognized in highly toxic arsenic metabolites, which was commonly found in human and animal urine. In the present study, we revealed the mechanism underlying the distribution and metabolism of non-thiolated and thiolated dimethylarsenic compounds such as dimethylarsinic acid (DMA{sup V}), dimethylarsinous acid (DMA{sup III}), dimethylmonothioarsinic acid (DMMTA{sup V}), and dimethyldithioarsinic acid (DMDTA{sup V}) after the administration of them into femoral vein of hamsters. DMA{sup V} and DMDTA{sup V} distributed in organs and body fluids were in their unmodified form, while DMA{sup III} and DMMTA{sup V} were bound to proteins and transformed to DMA{sup V} in organs. On the other hand, DMA{sup V} and DMDTA{sup V} were mostly excreted into urine as their intact form 1 h after post-injection, and more than 70% of the doses were recovered in urine as their intact form. By contrast, less than 8-14% of doses were recovered in urine as DMA{sup V}, while more than 60% of doses were distributed in muscles and target organs (liver, kidney, and lung) of hamsters after the injection of DMMTA{sup V} and DMA{sup III}. However, in red blood cells (RBCs), only a small amount of the arsenicals was distributed (less than 4% of the doses) after the injection of DMA{sup III} and DMMTA{sup V}, suggesting that the DMA{sup III} and DMMTA{sup V} were hardly accumulated in hamster RBCs. Based on these observations, we suggest that although DMMTA{sup V} and DMDTA{sup V} are thioarsenicals, DMMTA{sup V} is taken up efficiently by organs, in a manner different from that of DMDTA{sup V}. In addition, the distribution and metabolism of DMMTA{sup V} are like in manner similar to DMA{sup III} in hamsters, while DMDTA{sup V} is in a manner similar to DMA{sup V}.

  11. Metabolic Heat Regenerated Temperature Swing Adsorption for CO(sub 2) and Heat Removal/Rejection in a Martian PLSS

    NASA Technical Reports Server (NTRS)

    Iacomini, Christine; Powers, Aaron; Bowers, Chad; Straub-Lopez, Katie; Anderson, Grant; MacCallum, Taber; Paul, Heather

    2007-01-01

    Two of the fundamental problems facing the development of a Portable Life Support System (PLSS) for use on Mars, are (i) heat rejection (because traditional technologies use sublimation of water, which wastes a scarce resource and contaminates the premises), and (ii) rejection of CO2 in an environment with a ppCO2 of 0.4-0.9 kPa. Patent-pending Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is being developed to address both these challenges. The technology utilizes an adsorbent that when cooled with liquid CO2 to near sublimation temperatures (195K) removes metabolically-produced CO2 in the vent loop. Once fully loaded, the adsorbent is then warmed externally by the vent loop (approx. 300K), rejecting the captured CO2 to Mars ambient. Two beds are used to effect a continuous cycle of CO2 removal/rejection as well as facilitate heat exchange out of the vent loop. Any cryogenic fluid can be used in the application; however, since CO2 is readily available at Mars and can be easily produced and stored on the Martian surface, the solution is rather elegant and less complicated when employing liquid CO2. As some metabolic heat will need to be rejected anyway, finding a practical use for metabolic heat is also an overall benefit to the PLSS. To investigate the feasibility of the technology, a series of experiments was conducted which lead to the selection and partial characterization of an appropriate adsorbent. The adsorbent NaX successfully removed CO2 from a simulated vent loop at the prescribed temperature swing anticipated during PLSS operating conditions on Mars using a cryogenic fluid. Thermal conductivity of the adsorbent was also measured to eventually aid in a demonstrator design of the technology. These results provide no show stoppers to the development of MTSA technology and allow its development to focus on other design challenges as listed in the conclusions.

  12. The role of beaded activated carbon's pore size distribution on heel formation during cyclic adsorption/desorption of organic vapors.

    PubMed

    Jahandar Lashaki, Masoud; Atkinson, John D; Hashisho, Zaher; Phillips, John H; Anderson, James E; Nichols, Mark

    2016-09-01

    The effect of activated carbon's pore size distribution (PSD) on heel formation during adsorption of organic vapors was investigated. Five commercially available beaded activated carbons (BAC) with varying PSDs (30-88% microporous) were investigated. Virgin samples had similar elemental compositions but different PSDs, which allowed for isolating the contribution of carbon's microporosity to heel formation. Heel formation was linearly correlated (R(2)=0.91) with BAC micropore volume; heel for the BAC with the lowest micropore volume was 20% lower than the BAC with the highest micropore volume. Meanwhile, first cycle adsorption capacities and breakthrough times correlated linearly (R(2)=0.87 and 0.93, respectively) with BAC total pore volume. Micropore volume reduction for all BACs confirmed that heel accumulation takes place in the highest energy pores. Overall, these results show that a greater portion of adsorbed species are converted into heel on highly microporous adsorbents due to higher share of high energy adsorption sites in their structure. This differs from mesoporous adsorbents (low microporosity) in which large pores contribute to adsorption but not to heel formation, resulting in longer adsorbent lifetime. Thus, activated carbon with high adsorption capacity and high mesopore fraction is particularly desirable for organic vapor application involving extended adsorption/regeneration cycling. PMID:27173087

  13. Pore size distribution calculation from 1H NMR signal and N2 adsorption-desorption techniques

    NASA Astrophysics Data System (ADS)

    Hassan, Jamal

    2012-09-01

    The pore size distribution (PSD) of nano-material MCM-41 is determined using two different approaches: N2 adsorption-desorption and 1H NMR signal of water confined in silica nano-pores of MCM-41. The first approach is based on the recently modified Kelvin equation [J.V. Rocha, D. Barrera, K. Sapag, Top. Catal. 54(2011) 121-134] which deals with the known underestimation in pore size distribution for the mesoporous materials such as MCM-41 by introducing a correction factor to the classical Kelvin equation. The second method employs the Gibbs-Thompson equation, using NMR, for melting point depression of liquid in confined geometries. The result shows that both approaches give similar pore size distribution to some extent, and also the NMR technique can be considered as an alternative direct method to obtain quantitative results especially for mesoporous materials. The pore diameter estimated for the nano-material used in this study was about 35 and 38 Å for the modified Kelvin and NMR methods respectively. A comparison between these methods and the classical Kelvin equation is also presented.

  14. Distribution and metabolism of quaternary amines in salt marshes

    NASA Technical Reports Server (NTRS)

    King, Gary M.

    1985-01-01

    Quaternary amines such as glycine betaine (GBT) are common osmotically active solutes in much of the marine biota. GBT is accumulated by various bacteria, algae, higher plants, invertebrates, and vertebrates in response to salinity or water stresses; in some species, GBT occurs at tens to hundreds of millimolar concentrations and can account for a significant fraction of total nitrogen. Initial studies suggest that GBT is readily converted to two potential methane precursors, trimethylamine (TMA) and acetate, in anoxic sediments. TMA is apparently the most important methane precursor in surface sediments containing sulfate reducing bacteria. In salt marshes, the bulk of the methane formed may be due to the metabolism of TMA rather than other substrates. Current research is focussed on testing this hypothesis and on determining the role of quaternary amino osmoregulatory solutes in methane fluxes from marine environments. Preliminary studies have dealt with several problems: (1) determination of GBT concentrations in the dominant flora and fauna of salt marshes; (2) synthesis of radiolabelled GBT for metabolic studies; and (3) determination of fates of BGT in marine sediments using radiotracers. Both GC and HPLC techniques have been used to assay GBT concentrations in plant and animal tissues. S. alterniflora is probably the only significant source of GBT (and indirectly of methane) since the biomass and distribution of most other species is limited. Current estimates suggest that S. alterniflora GBT could account for most of the methane efflux from salt marshes.

  15. The absorption, distribution, metabolism and excretion of procyanidins.

    PubMed

    Zhang, Liang; Wang, Yijun; Li, Daxiang; Ho, Chi-Tang; Li, Junsong; Wan, Xiaochun

    2016-03-16

    Procyanidins (PAs) are polyphenols in plant food that have many health benefits, including cancer prevention, cardiovascular protection and diabetes prevention. PAs have been known to have low oral bioavilability. In this review, we summarize the published results on the ADME (absorption, distribution, metabolism and excretion) of PAs in vivo and in vitro. After oral administration, in the stomach the decomposition of PAs is highly dependent on the pH value of gastric juice, which is also affected by food intake. In the small intestine, PA polymers and oligomers with DP > 4 are not directly absorbed in vivo, but minor PA monomers and dimers could be detected in the plasma. Methylated and glucuronidated PA dimers and monomers are the main metabolites of PAs in plasma. In the colon, PAs are catabolized by colonic microflora into a series of low molecular weight phenolic acids, such as phenyl valerolactone, phenylacetic acids and phenylpropionic acids. We reviewed the degradation of PAs in gastric digestion, the absorption of PAs in the small intestine and the metabolic pathway of PAs by colonic microflora. To clearly explain the in vivo pharmacokinetics of PAs, a systematic comparative analysis on previously published data on PAs was conducted. PMID:26814915

  16. Tissue distribution, disposition, and metabolism of cyclosporine in rats

    SciTech Connect

    Wagner, O.; Schreier, E.; Heitz, F.; Maurer, G.

    1987-05-01

    Tissue distribution, disposition, and metabolism of /sup 3/H-cyclosporine were studied in rats after single and repeated oral doses of 10 and 30 mg/kg and after an iv dose of 3 mg/kg. The oral doses of 10 and 30 mg/kg were dissolved in polyethylene glycol 200/ethanol or in olive oil/Labrafil/ethanol. Absorption from both formulations was slow and incomplete, with peak /sup 3/H blood levels at 3-4 hr. Approximately 30% of the radioactive dose was absorbed, which is consistent with oral bioavailability data for cyclosporine. More than 70% of the radioactivity was excreted in feces and up to 15% in urine. Elimination via the bile accounted for 10 and 60% of the oral and iv doses, respectively. Since unchanged cyclosporine predominated in both blood and tissues at early time points, the half-lives of the distribution phases (t 1/2 alpha) of parent drug and of total radioactivity were similar. In blood, kidney, liver, and lymph nodes, t 1/2 alpha of cyclosporine ranged from 6-10 hr. Elimination of radioactivity from the systemic circulation was multiphasic, with a terminal half-life of 20-30 hr. /sup 3/H-Cyclosporine was extensively distributed throughout the body, with highest concentrations in liver, kidney, endocrine glands, and adipose tissue. The concentrations of both total radioactivity and parent drug were greater in tissues than in blood, which is consistent with the high lipid solubility of cyclosporine and some of its metabolites. Skin and adipose tissue were the main storage sites for unchanged cyclosporine. Elimination half-lives were slower for most tissues than for blood and increased with multiple dosing. The amount of unchanged drug was negligible in urine and bile.

  17. Metabolic Heat Regenerated Temperature Swing Adsorption for CO2 and Heat Removal/Rejection in a Martian PLSS

    NASA Technical Reports Server (NTRS)

    Iacomini, Christine; Powers, Aaron; Bower, Chad; Straub-Lopez, Kathrine; Anderson, Grant; MacCallum, Taber; Paul, Heather L.

    2007-01-01

    Two of the fundamental problems facing the development of a Portable Life Support System (PLSS) for use on Mars, are (i) heat rejection (because traditional technologies use sublimation of water, which wastes a scarce resource and contaminates the premises), and (ii) rejection of carbon dioxide (CO2) in an environment with a CO2 partial pressure (ppCO2) of 0.4-0.9 kPa. Patent-pending Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is being developed to address both these challenges. The technology utilizes an adsorbent that when cooled with liquid CO2 to near sublimation temperatures (195K) removes metabolically-produced CO2 in the ventilation loop. Once fully loaded, the adsorbent is then warmed externally by the ventilation loop (300K), rejecting the captured CO2 to Mars ambient. Two beds are used to provide a continuous cycle of CO2 removal/rejection as well as facilitate heat exchange out of the ventilation loop. Any cryogenic fluid can be used in the application; however, since CO2 is readily available on Mars and can be easily produced and stored on the Martian surface, the solution is rather elegant and less complicated when employing liquid CO2. As some metabolic heat will need to be rejected anyway, finding a practical use for metabolic heat is also an overall benefit to the PLSS. To investigate the feasibility of the technology, a series of experiments were conducted which lead to the selection and partial characterization of an appropriate adsorbent. The Molsiv Adsorbents 13X 8x12 (also known as NaX zeolite) successfully removed CO2 from a simulated ventilation loop at the prescribed temperature swing anticipated during PLSS operating conditions on Mars using a cryogenic fluid. Thermal conductivity of the adsorbent was also measured to eventually aid in a demonstrator design of the technology. These results provide no show stoppers to the development of MTSA technology and allow its development to focus on other design

  18. Design and Assembly of an Integrated Metabolic Heat Regenerated Temperature Swing Adsorption (MTSA) Subassembly Engineering Development Unit

    NASA Technical Reports Server (NTRS)

    Padilla, Sebastian A.; Powers, Aaron; Iacomini, Christie S.; Bower, Chad E.; Paul, Heather L.

    2012-01-01

    Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is being developed for thermal and carbon dioxide (CO2) control for a Portable Life Support System (PLSS), as well as water recycling. The core of the MTSA technology is a sorbent bed that removes CO2 from the PLSS ventilation loop gas via a temperature swing. A Condensing Icing Heat eXchanger (CIHX) is used to warm the sorbent while also removing water from the ventilation loop gas. A Sublimation Heat eXchanger (SHX) is used to cool the sorbent. Research was performed to explore an MTSA designed for both lunar and Martian operations. Previously the sorbent bed, CIHX, and SHX had been built and tested individually on a scale relevant to PLSS operations, but they had not been done so as an integrated subassembly. Design and analysis of an integrated subassembly was performed based on this prior experience and an updated transient system model. Focus was on optimizing the design for Martian operations, but the design can also be used in lunar operations. An Engineering Development Unit (EDU) of an integrated MTSA subassembly was assembled based on the design. Its fabrication is discussed. Some details on the differences between the as-assembled EDU and the future flight unit are considered.

  19. Design and Assembly of an Integrated Metabolic Heat Regenerated Temperature Swing Adsorption (MTSA) Subassembly Engineering Development Unit

    NASA Technical Reports Server (NTRS)

    Padilla, Sebastian A.; Powers, Aaron; Iacomini, Christie S.; Paul, Heather L.

    2011-01-01

    Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is being developed for thermal and carbon dioxide (CO2) control for a Portable Life Support System (PLSS), as well as water recycling. The core of the MTSA technology is a sorbent bed that removes CO2 from the PLSS ventilation loop gas via a temperature swing. A Condensing Ice Heat eXchanger (CIHX) is used to warm the sorbent while also removing water from the ventilation loop gas. A Sublimation Heat eXchanger (SHX) is used to cool the sorbent. Research was performed to explore an MTSA designed for both lunar and Martian operations. Previously each the sorbent bed, CIHX, and SHX had been built and tested individually on a scale relevant to PLSS operations, but they had not been done so as an integrated subassembly. Design and analysis of an integrated subassembly was performed based on this prior experience and an updated transient system model. Focus was on optimizing the design for Martian operations, but the design can also be used in lunar operations. An Engineering Development Unit (EDU) of an integrated MTSA subassembly was assembled based on the design. Its fabrication is discussed. Some details on the differences between the as-assembled EDU to the future flight unit are considered.

  20. Pore Scale Heterogeneity in the Mineral Distribution, Surface Area and Adsorption in Porous Rocks

    NASA Astrophysics Data System (ADS)

    Lai, P. E. P.; Krevor, S. C.

    2014-12-01

    The impact of heterogeneity in chemical transport and reaction is not understood in continuum (Darcy/Fickian) models of reactive transport. This is manifested in well-known problems such as scale dependent dispersion and discrepancies in reaction rate observations made at laboratory and field scales [1]. Additionally, this is a source of uncertainty for carbon dioxide injection, which produces a reactive fluid-rock system particularly in carbonate rock reservoirs. A potential cause is the inability of the continuum approach to incorporate the impact of heterogeneity in pore-scale reaction rates. This results in part from pore-scale heterogeneities in surface area of reactive minerals [2, 3]. We use x-ray micro tomography to describe the non-normal 3-dimensional distribution of reactive surface area within a porous medium according to distinct mineral groups. Using in-house image processing techniques, thin sections, nitrogen BET surface area, backscattered electron imaging and energy dispersive spectroscopy, we compare the surface area of each mineral phase to those obtained from x-ray CT imagery. In all samples, there is little correlation between the reactive surface area fraction and the volumetric fraction of a mineral in a bulk rock. Berea sandstone was far less heterogeneous and has a characteristic pore size at which a surface area distribution may be used to quantify heterogeneity. In carbonates, heterogeneity is more complex and surface area must be characterized at multiple length scales for an accurate description of reactive transport. We combine the mineral specific surface area characterisation to dynamic tomography, imaging the flow of water and solutes, to observe flow dependent and mineral specific adsorption. The observations may contribute to the incorporation of experimentally based statistical descriptions of pore scale heterogeneity in reactive transport into upscaled models, moving it closer to predictive capabilities for field scale

  1. Unified method for the total pore volume and pore size distribution of hierarchical zeolites from argon adsorption and mercury intrusion.

    PubMed

    Kenvin, Jeffrey; Jagiello, Jacek; Mitchell, Sharon; Pérez-Ramírez, Javier

    2015-02-01

    A generalized approach to determine the complete distribution of macropores, mesopores, and micropores from argon adsorption and mercury porosimetry is developed and validated for advanced zeolite catalysts with hierarchically structured pore systems in powder and shaped forms. Rather than using a fragmented approach of simple overlays from individual techniques, a unified approach that utilizes a kernel constructed from model isotherms and model intrusion curves is used to calculate the complete pore size distribution and the total pore volume of the material. An added benefit of a single full-range pore size distribution is that the cumulative pore area and the area distribution are also obtained without the need for additional modeling. The resulting complete pore size distribution and the kernel accurately model both the adsorption isotherm and the mercury porosimetry. By bridging the data analysis of two primary characterization tools, this methodology fills an existing gap in the library of familiar methods for porosity assessment in the design of materials with multilevel porosity for novel technological applications. PMID:25603366

  2. Multi-scale modularity and motif distributional effect in metabolic networks.

    PubMed

    Gao, Shang; Chen, Alan; Rahmani, Ali; Zeng, Jia; Tan, Mehmet; Alhajj, Reda; Rokne, Jon; Demetrick, Douglas; Wei, Xiaohui

    2016-01-01

    Metabolism is a set of fundamental processes that play important roles in a plethora of biological and medical contexts. It is understood that the topological information of reconstructed metabolic networks, such as modular organization, has crucial implications on biological functions. Recent interpretations of modularity in network settings provide a view of multiple network partitions induced by different resolution parameters. Here we ask the question: How do multiple network partitions affect the organization of metabolic networks? Since network motifs are often interpreted as the super families of evolved units, we further investigate their impact under multiple network partitions and investigate how the distribution of network motifs influences the organization of metabolic networks. We studied Homo sapiens, Saccharomyces cerevisiae and Escherichia coli metabolic networks; we analyzed the relationship between different community structures and motif distribution patterns. Further, we quantified the degree to which motifs participate in the modular organization of metabolic networks. PMID:26412791

  3. MAMMALIAN METABOLISM AND DISTRIBUTION OF PERFLUOROOCTYL ETHANOL (8-2 TELOMER ALCOHOL) AND ITS OXIDATION METABOLITES

    EPA Science Inventory

    Perfluorinated compounds have been shown to be globally distributed, bioaccumulative, persistent and potentially toxic. It has been hypothesized that many precursor fluorinated compounds, including the telomer alcohols, degrade or metabolize to the common metabolite PFOA.

  4. The distribution of nitrogen species and adsorption of ammonium in sediments from the tidal Potomac River and estuary

    NASA Astrophysics Data System (ADS)

    Simon, N. S.; Kennedy, M. M.

    1987-07-01

    The distribution of dissolved ammonium, adsorbed ammonium and residual, organic and total nitrogen was measured in Potomac River tidal, transition zone and lower estuary sediments to a depth of 66 cm. For these sediments, exchangeable ammonium, and thereby adsorbed ammonium concentrations, were determined directly using an ammonia electrode in alkaline sediment suspensions. Ammonia electrode data were comparable to data obtained by KCl extraction of fresh sediment. The conventional unitless ammonium adsorption coefficient, calculated as the slope of the regression line drawn when sediment-adsorbed ammonium (μmol g -1 dry wt of sediment) is plotted against interstitial water ammonium (μmol g -1 dry wt sediment), is 1·5 for this system. When a modified ammonium adsorption coefficient is calculated from sediment-adsorbed ammonium concentrations and a ratio of interstitial water ammonium and potassium concentrations, the regression equation through the data has a zero intercept and is more nearly linear than the regression equation of data based on conventional calculations. The use of a ratio including ammonium and potassium concentrations in the interstitial water term takes into account ionic strength variations in the estuary and competition between ammonium and potassium for adsorption sites.

  5. Quantitative Distribution and Metabolism of Auxin Herbicides in Roots 1

    PubMed Central

    Scott, Peter C.; Morris, Roy O.

    1970-01-01

    The internal concentrations of four auxin herbicides— 2,4-dichlorophenoxyacetic acid, dicamba, picloram, and naphthaleneacetic acid—were measured in the roots of treated pea seedlings. Intact seedlings were immersed in solutions of labeled herbicides at concentrations sufficient to produce toxic symptoms (inhibition of elongation, radial enlargement, and lateral root proliferation). Measurements of volume and herbicide content of segments taken sequentially along the root showed that an acropetal concentration gradient of each herbicide was established within the root immediately following treatment. Although there was a net loss of herbicide in the following 24 hours, the gradient was maintained. Initially, the concentration of herbicide in the root tips exceeded that in the external medium. In support of the contention that toxic symptoms due to herbicide treatment are caused by the presence of unmetabolized chemical at the site of action, it was found that metabolism was negligible for all herbicides except naphthaleneacetic acid. PMID:16657529

  6. Invariability of Central Metabolic Flux Distribution in Shewanella oneidensis MR-1 Under Environmental or Genetic Perturbations

    SciTech Connect

    Tang, Yinjie; Martin, Hector Garcia; Deutschbauer, Adam; Feng, Xueyang; Huang, Rick; Llora, Xavier; Arkin, Adam; Keasling, Jay D.

    2009-04-21

    An environmentally important bacterium with versatile respiration, Shewanella oneidensis MR-1, displayed significantly different growth rates under three culture conditions: minimal medium (doubling time {approx} 3 hrs), salt stressed minimal medium (doubling time {approx} 6 hrs), and minimal medium with amino acid supplementation (doubling time {approx}1.5 hrs). {sup 13}C-based metabolic flux analysis indicated that fluxes of central metabolic reactions remained relatively constant under the three growth conditions, which is in stark contrast to the reported significant changes in the transcript and metabolite profiles under various growth conditions. Furthermore, ten transposon mutants of S. oneidensis MR-1 were randomly chosen from a transposon library and their flux distributions through central metabolic pathways were revealed to be identical, even though such mutational processes altered the secondary metabolism, for example, glycine and C1 (5,10-Me-THF) metabolism.

  7. Untangling hyporheic residence time distributions and whole stream metabolisms using a hydrological process model

    NASA Astrophysics Data System (ADS)

    Altenkirch, Nora; Mutz, Michael; Molkenthin, Frank; Zlatanovic, Sanja; Trauth, Nico

    2016-04-01

    The interaction of the water residence time in hyporheic sediments with the sediment metabolic rates is believed to be a key factor controlling whole stream metabolism. However, due to the methodological difficulties, there is little data that investigates this fundamental theory of aquatic ecology. Here, we report on progress made to combine numerical modeling with a series of manipulation to laboratory flumes overcoming methodological difficulties. In these flumes, hydraulic conditions were assessed using non-reactive tracer and heat pulse sensor. Metabolic activity was measured as the consumption and production of oxygen and the turnover of reactive tracers. Residence time and metabolic processes were modeled using a multicomponent reactive transport code called Min3P and calibrated with regard to the hydraulic conditions using the results obtained from the flume experiments. The metabolic activity was implemented in the model via Monod type expressions e.g. for aerobic respiration rates. A number of sediment structures differing in residence time distributions were introduced in both, the model and the flumes, specifically to model the biogeochemical performance and to validate the model results. Furthermore, the DOC supply and surface water flow velocity were altered to test the whole stream metabolic response. Using the results of the hydrological process model, a sensitivity analysis of the impact of residence time distributions on the metabolic activity could yield supporting proof of an existing link between the two.

  8. Thidiazuron uptake, distribution and metabolism in bluegills and channel catfish.

    PubMed

    Knowles, C O; Benezet, H J; Mayer, F L

    1980-01-01

    Bluegills (Lepomis macrochirus) exposed to 0.1 ppm of thidiazuron-14C cotton defoliant for 28 days under continuous flow conditions accumulated relatively low levels of radiocarbon. The maximum detected was 5.4 ppm in fillet tissue after 1 day. During a 14 day depuration period, radioactivity declined to 1.0 ppm or less. Fractionation of offal and fillet tissues from bluegills collected at 28 days indicated that most of the radioactive material was water soluble, although appreciable amounts of organosoluble radioactive material also were present. When bluegills were injected intraperitoneally with thidiazuron-14C, metabolism and elimination were relatively rapid. Organosoluble radioactive material isolated from fish tissue included thidiazuron, its 2-hydroxyphenyl derivative, phenylurea, and several unknowns. Channel catfish (Ictalurus punctatus) exposed under static conditions to a system containing 0.15 ppm of thidiazuron-14C incorporated into soil also accumulated only low concentrations of radiocarbon. The maximum detected was 2.5 ppb in offal tissue at 7 days. In fillet tissue, radioactivity did not exceed 0.5 ppb. There was no evidence from these studies to indicate that thidiazuron would pose a hazard to the aquatic ecosystem. PMID:7400538

  9. Glucose metabolic flux distribution of Lactobacillus amylophilus during lactic acid production using kitchen waste saccharified solution

    PubMed Central

    Liu, Jianguo; Wang, Qunhui; Zou, Hui; Liu, Yingying; Wang, Juan; Gan, Kemin; Xiang, Juan

    2013-01-01

    The 13C isotope tracer method was used to investigate the glucose metabolic flux distribution and regulation in Lactobacillus amylophilus to improve lactic acid production using kitchen waste saccharified solution (KWSS). The results demonstrate that L. amylophilus is a homofermentative bacterium. In synthetic medium, 60.6% of the glucose entered the Embden–Meyerhof–Parnas (EMP) to produce lactic acid, whereas 36.4% of the glucose entered the pentose phosphate metabolic pathway (HMP). After solid–liquid separation of the KWSS, the addition of Fe3+ during fermentation enhanced the NADPH production efficiency and increased the NADH content. The flux to the EMP was also effectively increased. Compared with the control (60.6% flux to EMP without Fe3+ addition), the flux to the EMP with the addition of Fe3+ (74.3%) increased by 23.8%. In the subsequent pyruvate metabolism, Fe3+ also increased lactate dehydrogenase activity, and inhibited alcohol dehydrogenase, pyruvate dehydrogenase and pyruvate carboxylase, thereby increasing the lactic acid production to 9.03 g l−1, an increase of 8% compared with the control. All other organic acid by-products were lower than in the control. However, the addition of Zn2+ showed an opposite effect, decreasing the lactic acid production. In conclusion it is feasible and effective means using GC-MS, isotope experiment and MATLAB software to integrate research the metabolic flux distribution of lactic acid bacteria, and the results provide the theoretical foundation for similar metabolic flux distribution. PMID:23489617

  10. Adsorption, uptake and distribution of gold nanoparticles in Daphnia magna following long term exposure.

    PubMed

    Botha, Tarryn Lee; Boodhia, Kailen; Wepener, Victor

    2016-01-01

    Gold nanoparticles (nAu) have recently been studied and developed within the biological and photothermal therapeutic contexts. The major clinical interest is within the application of novel drug delivery systems. Environmental exposure to nanoparticles can occur in different stages of the lifecycle of the product; from their synthesis, applications, product weathering and their disposal. Freshwater Daphnids, specifically Daphnia magna, have been used since the 1960s as a standard species in acute and chronic aquatic toxicity testing. Visualization of the interactions and uptake of nAu by D. magna was related to reproduction and molting patterns. Exposure to nAu was done using a chronic reproduction test performed for 14 days at six concentrations (0.5mg/L, 2mg/L, 5mg/L, 10mg/L, 15mg/L and 20mg/L). Microscopy was used to determine whether there was any uptake or interaction of nAu with daphnia. However the concentration of nAu in the media and the charge of particles played a role in the uptake and surface adsorption. As exposure concentrations of nAu increased it appeared that the nAu aggregated onto the surface and in the gut of the organisms in higher concentrations. There was no evidence of nAu internalization into the body cavity of the daphnia. Aquatic exposure to nAu resulted in increased adhesion of the particles to the carapace of daphnia, ingestion and uptake into the gut of daphnia and had no significant effect on reproduction and molting patterns. PMID:26650707

  11. The Adsorption of Arsenic on Iron Pipes in Water Distribution Systems

    EPA Science Inventory

    In order to remain compliant with the U.S. EPA’s Lead and Copper rule, it is pivotal to understand the relationship between factors affecting lead release in drinking water distribution systems. Lead solids were synthesized in cell experiments using a pH range of 6-11 with both 1...

  12. Prediction of Metabolic Flux Distribution from Gene Expression Data Based on the Flux Minimization Principle

    PubMed Central

    Song, Hyun-Seob; Reifman, Jaques; Wallqvist, Anders

    2014-01-01

    Prediction of possible flux distributions in a metabolic network provides detailed phenotypic information that links metabolism to cellular physiology. To estimate metabolic steady-state fluxes, the most common approach is to solve a set of macroscopic mass balance equations subjected to stoichiometric constraints while attempting to optimize an assumed optimal objective function. This assumption is justifiable in specific cases but may be invalid when tested across different conditions, cell populations, or other organisms. With an aim to providing a more consistent and reliable prediction of flux distributions over a wide range of conditions, in this article we propose a framework that uses the flux minimization principle to predict active metabolic pathways from mRNA expression data. The proposed algorithm minimizes a weighted sum of flux magnitudes, while biomass production can be bounded to fit an ample range from very low to very high values according to the analyzed context. We have formulated the flux weights as a function of the corresponding enzyme reaction's gene expression value, enabling the creation of context-specific fluxes based on a generic metabolic network. In case studies of wild-type Saccharomyces cerevisiae, and wild-type and mutant Escherichia coli strains, our method achieved high prediction accuracy, as gauged by correlation coefficients and sums of squared error, with respect to the experimentally measured values. In contrast to other approaches, our method was able to provide quantitative predictions for both model organisms under a variety of conditions. Our approach requires no prior knowledge or assumption of a context-specific metabolic functionality and does not require trial-and-error parameter adjustments. Thus, our framework is of general applicability for modeling the transcription-dependent metabolism of bacteria and yeasts. PMID:25397773

  13. Tissue distribution, metabolism, and clearance of the convulsant trimethylolpropane phosphate in rats.

    PubMed

    Rossi, J; Jung, A E; Ritchie, G D; Lindsey, J W; Nordholm, A F

    1998-11-01

    The distribution, metabolism, and clearance of trimethylolpropane phosphate (TMPP), a potent, bicyclophosphate, gamma-aminobutyric acid-ergic convulsant, were studied in male Fischer-344 rats. Intraperitoneal administration of TMPP was compared with oral gavage with respect to rates of absorption, distribution, and clearance. Distribution of TMPP to major body tissues was evaluated for the first 24 hr after administration or, in the case of regional brain distribution, immediately after the first TMPP-induced clinical seizure. Samples purified from the urine, feces, and bile of rats exposed to TMPP, as well as from rat liver microsomes incubated with TMPP in vitro, were analyzed for possible phase I and phase II metabolism, using HPLC. The disposition and clearance of TMPP in the blood and major body tissues were measured. TMPP was found to be well distributed to highly vascularized tissue compartments, with little retention >24 hr after administration. TMPP was eliminated through the urine and feces as the parent compound, with no evidence of phase I or phase II metabolism. TMPP was rapidly cleared from the blood during the first 30 min after exposure, with slower clearance of >87% of the drug during the following 8-hr period and >99.5% clearance by 100 hr after injection. Repeated daily exposure to TMPP for up to 5 successive days resulted in no measurable accumulation in the brain or other major tissue compartments. Possible mechanisms for TMPP-induced, short- and long-term, neurobehavioral modulation are discussed. PMID:9806946

  14. Use of In Vitro Absorption, Distribution, Metabolism, and Excretion (ADME) Data in Bioaccumulation Assessments for Fish

    SciTech Connect

    Nichols, John W.; Erhardt, Susan; Dyer, Scott; James, Margaret O.; Moore, Margo; Plotzke, Kathleen; Segner, Helmut; Schultz, Irvin R.; Thomas, Karluss; Vasiluk, Luba; Weisbrod, Anne V.

    2007-11-01

    A scientific workshop was held in 2006 to discuss the use of in vitro Absorption, Distribution, Metabolism, and Excretion (ADME) data in chemical bioaccumulation assessments for fish. Computer-based (in silico) modeling tools are widely used to estimate chemical bioaccumulation. These in silico methods have inherent limitations that result in inaccurate estimates for many compounds. Based on a review of the science workshop participants concluded that two factors, absorption and metabolism, represent the greatest sources of uncertainty in current bioaccumulation models. Both factors can be investigated experimentally using in vitro test systems.

  15. Distribution or adsorption: the major dilemma in reversed-phase HPLC

    NASA Astrophysics Data System (ADS)

    Deineka, V. I.

    2008-06-01

    A method is suggested for analyzing the dependences obtained for different compositions of mobile eluent system phases, their slopes and intercepts, log k( i, B) = a + b log k ( i, A), where a is the intercept for the A and B stationary phases and b is the proportionality factor. An analysis requires parallel investigation of sorbate retention on at least three stationary phases with different lengths of grafted hydrocarbon radicals. The dependence of correlation parameters on the sorbate retention mechanism is discussed. It is shown that the hypothetical dependences coincide with the experimental dependences for surface sorption of resveratrol and volume distribution of triglycerides.

  16. Effect of seawater salinity on pore-size distribution on a poly(styrene)-based HP20 resin and its adsorption of diarrhetic shellfish toxins.

    PubMed

    Fan, Lin; Sun, Geng; Qiu, Jiangbing; Ma, Qimin; Hess, Philipp; Li, Aifeng

    2014-12-19

    In the present study, okadaic acid (OA) and dinophysistoxin-1 (DTX1) were spiked into artificial seawater at low, medium and high estuarine salinities (9‰, 13.5‰ and 27‰). Passive samplers (HP20 resin) used for solid phase adsorption toxin tracking (SPATT) technology were exposed in these seawaters for 12-h periods. Adsorption curves well fitted a pseudo-secondary kinetics model. The highest initial sorption rates of both toxins occurred in the seawater of medium salinity, followed by seawater of low and high estuarine salinity. Pore volumes of micropores (<2 nm) and small mesopores (2 nmadsorption of toxins in seawater at high and low salinity but not in seawater at medium salinity, which demonstrated that the toxin molecules entered into micropores and mesopores (below 10nm in size) in seawaters of high and low salinity. More toxin or other matrix agglomerates were displayed on the surface of resin deployed in the seawater of medium salinity. Taking into consideration the pore-size distribution and surface images, it appears that intra-particle diffusion governs toxin adsorption in seawater at high salinity while film diffusion mainly controls the adsorption process in seawater at medium salinity. This is the first study to confirm that molecules of OA and DTX1 are able to enter into micropores (<2nm) and small mesopores (2-10nm) of HP20 resin in estuarine seawater with high salinity (∼27‰). PMID:25464996

  17. Glucose metabolic flux distribution of Lactobacillus amylophilus during lactic acid production using kitchen waste saccharified solution.

    PubMed

    Liu, Jianguo; Wang, Qunhui; Zou, Hui; Liu, Yingying; Wang, Juan; Gan, Kemin; Xiang, Juan

    2013-11-01

    The (13) C isotope tracer method was used to investigate the glucose metabolic flux distribution and regulation in Lactobacillus amylophilus to improve lactic acid production using kitchen waste saccharified solution (KWSS). The results demonstrate that L. amylophilus is a homofermentative bacterium. In synthetic medium, 60.6% of the glucose entered the Embden-Meyerhof-Parnas (EMP) to produce lactic acid, whereas 36.4% of the glucose entered the pentose phosphate metabolic pathway (HMP). After solid-liquid separation of the KWSS, the addition of Fe(3+) during fermentation enhanced the NADPH production efficiency and increased the NADH content. The flux to the EMP was also effectively increased. Compared with the control (60.6% flux to EMP without Fe(3+) addition), the flux to the EMP with the addition of Fe(3+) (74.3%) increased by 23.8%. In the subsequent pyruvate metabolism, Fe(3+) also increased lactate dehydrogenase activity, and inhibited alcohol dehydrogenase, pyruvate dehydrogenase and pyruvate carboxylase, thereby increasing the lactic acid production to 9.03 g l(-1) , an increase of 8% compared with the control. All other organic acid by-products were lower than in the control. However, the addition of Zn(2+) showed an opposite effect, decreasing the lactic acid production. In conclusion it is feasible and effective means using GC-MS, isotope experiment and MATLAB software to integrate research the metabolic flux distribution of lactic acid bacteria, and the results provide the theoretical foundation for similar metabolic flux distribution. PMID:23489617

  18. Radionuclide adsorption distribution coefficients measured in Hanford sediments for the low level waste performance assessment project

    SciTech Connect

    Kaplan, D.I.; Serne, R.J.; Owen, A.T.

    1996-08-01

    Preliminary modeling efforts for the Hanford Site`s Low Level Waste-Performance Assessment (LLW PA) identified {sup 129}I, {sup 237}Np, {sup 79}Se, {sup 99}Tc, and {sup 234},{sup 235},{sup 238}U as posing the greatest potential health hazard. It was also determined that the outcome of these simulations was very sensitive to the parameter describing the extent to which radionuclides sorb to the subsurface matrix, i.e., the distribution coefficient (K{sub d}). The distribution coefficient is a ratio of the radionuclide concentration associated with the solid phase to that in the liquid phase. The objectives of this study were to (1) measure iodine, neptunium, technetium, and uranium K{sub d} values using laboratory conditions similar to those expected at the LLW PA disposal site, and (2) evaluate the effect of selected environmental parameters, such as pH, ionic strength, moisture concentration, and radio nuclide concentration, on K{sub d} values of selected radionuclides. It is the intent of these studies to develop technically defensible K{sub d} values for the PA. The approach taken throughout these studies was to measure the key radio nuclide K{sub d} values as a function of several environmental parameters likely to affect their values. Such an approach provides technical defensibility by identifying the mechanisms responsible for trends in K{sub d} values. Additionally, such studies provide valuable guidance regarding the range of K{sub d} values likely to be encountered in the proposed disposal site.

  19. Ecology Drives the Distribution of Specialized Tyrosine Metabolism Modules in Fungi

    PubMed Central

    Greene, George H.; McGary, Kriston L.; Rokas, Antonis; Slot, Jason C.

    2014-01-01

    Gene clusters encoding accessory or environmentally specialized metabolic pathways likely play a significant role in the evolution of fungal genomes. Two such gene clusters encoding enzymes associated with the tyrosine metabolism pathway (KEGG #00350) have been identified in the filamentous fungus Aspergillus fumigatus. The l-tyrosine degradation (TD) gene cluster encodes a functional module that facilitates breakdown of the phenolic amino acid, l-tyrosine through a homogentisate intermediate, but is also involved in the production of pyomelanin, a fungal pathogenicity factor. The gentisate catabolism (GC) gene cluster encodes a functional module likely involved in phenolic compound degradation, which may enable metabolism of biphenolic stilbenes in multiple lineages. Our investigation of the evolution of the TD and GC gene clusters in 214 fungal genomes revealed spotty distributions partially shaped by gene cluster loss and horizontal gene transfer (HGT). Specifically, a TD gene cluster shows evidence of HGT between the extremophilic, melanized fungi Exophiala dermatitidis and Baudoinia compniacensis, and a GC gene cluster shows evidence of HGT between Sordariomycete and Dothideomycete grass pathogens. These results suggest that the distribution of specialized tyrosine metabolism modules is influenced by both the ecology and phylogeny of fungal species. PMID:24391152

  20. Metabolism

    MedlinePlus

    Metabolism refers to all the physical and chemical processes in the body that convert or use energy, ... Tortora GJ, Derrickson BH. Metabolism. In: Tortora GJ, Derrickson BH. Principles of Anatomy and Physiology . 14th ed. Hoboken, NJ: John H Wiley and Sons; 2013: ...

  1. Complex interactions between dietary and genetic factors impact lycopene metabolism and distribution

    PubMed Central

    Moran, Nancy E.; Erdman, John W.; Clinton, Steven K.

    2013-01-01

    Intake of lycopene, a red, tetraterpene carotenoid found in tomatoes is epidemiologically associated with a decreased risk of chronic disease processes, and lycopene has demonstrated bioactivity in numerous in vitro and animal models. However, our understanding of absorption, tissue distribution, and biological impact in humans remains very limited. Lycopene absorption is strongly impacted by dietary composition, especially the amount of fat. Concentrations of circulating lycopene in lipoproteins may be further influenced by a number of variations in genes related to lipid absorption and metabolism. Lycopene is not uniformly distributed among tissues, with adipose, liver, and blood being the major body pools, while the testes, adrenals, and liver have the greatest concentrations compared to other organs. Tissue concentrations of lycopene are likely dictated by expression of and genetic variation in lipoprotein receptors, cholesterol transporters, and carotenoid metabolizing enzymes, thus impacting lycopene accumulation at target sites of action. The novel application of genetic evaluation in concert with lycopene tracers will allow determination of which genes and polymorphisms define individual lycopene metabolic phenotypes, response to dietary variables, and ultimately determine biological and clinical outcomes. A better understanding of the relationship between diet, genetics, and lycopene distribution will provide necessary information to interpret epidemiological findings more accurately and to design effective, personalized clinical nutritional interventions addressing hypotheses regarding health outcomes. PMID:23845854

  2. Subcellular distribution of key enzymes of lipid metabolism during the euthermia-hibernation-arousal cycle

    PubMed Central

    Suozzi, Anna; Malatesta, Manuela; Zancanaro, Carlo

    2009-01-01

    Mammalian hibernation is a natural, fully reversible hypometabolic state characterized by a drastic reduction of body temperature and metabolic activity, which ensures survival to many species under adverse environmental conditions. During hibernation, many hibernators rely for energy supply almost exclusively on lipid reserves; the shift from carbohydrate to lipid metabolism implies profound rearrangement of the anabolic and catabolic pathways of energetic substrates. However, the structural counterpart of such adaptation is not known. In this study we investigated, by using immunoelectron microscopy, the fine intracellular distribution of two key enzymes involved in lipid metabolism, namely, the fatty acid synthase (FAS) and the long-chain fatty acyl-CoA synthetase (ACSL), in hepatocytes of euthermic, hibernating and arousing hazel dormice. Our results show that the two enzymes are differentially distributed in cellular compartments (cytoplasm, mitochondria and cell nuclei) of hepatocytes during euthermia. Quantitative redistribution of both enzymes among cellular compartments takes place during hibernation and arousal, in accordance with the physiological changes. Interestingly, this redistribution follows different seasonal patterns in cytoplasm, mitochondria and nuclei. In conclusion, our data represent the first quantitative morphological evidence of lipid enzyme distribution in a true hibernator throughout the year cycle, thus providing a structural framework to biochemical changes associated with the hypometabolism of hibernation. PMID:19538638

  3. Phycoremediation and adsorption isotherms of cadmium and copper ions by Merismopedia tenuissima and their effect on growth and metabolism.

    PubMed

    Fawzy, Mustafa A

    2016-09-01

    The current study tends to investigate the removal of cadmium and copper ions by Merismopedia tenuissima, grown in different concentrations of cadmium and copper ions, as well to investigate their effects on growth and metabolism. Sorption isotherms of Langmuir and Freundlich were obtained for the quantitative description of cadmium and copper uptake by M. tenuissima. Langmuir model adequately to describe the data of biosorption for these metals. However, the Freundlich model could work well in case of Cu(2+) only. M. tenuissima appears to be more efficient for removing Cd(2+) ions than Cu(2+). However, the affinity constant of Cu(2+) on the biomass of M. tenuissima was higher than Cd(2+) indicating that M. tenuissima is more tolerant to Cd(2+) phytotoxicity than Cu(2+). FTIR analysis of algae with and without biosorption revealed the presence of carboxyl, amino, amide and hydroxyl groups, which were responsible for biosorption of Cd(+2) and Cu(+2) ions. PMID:27458699

  4. Identification of Absorption, Distribution, Metabolism, and Excretion (ADME) Genes Relevant to Steatosis Using a Differential Gene Expression Approach

    EPA Science Inventory

    Absorption, distribution, metabolism, and excretion (ADME) parameters represent important connections between exposure to chemicals and the activation of molecular initiating events of Adverse Outcome Pathways (AOPs) in cellular, tissue, and organ level targets. ADME parameters u...

  5. Spatial Distribution of the Metabolically Active Microbiota within Italian PDO Ewes' Milk Cheeses.

    PubMed

    De Pasquale, Ilaria; Di Cagno, Raffaella; Buchin, Solange; De Angelis, Maria; Gobbetti, Marco

    2016-01-01

    Italian PDO (Protected Designation of Origin) Fiore Sardo (FS), Pecorino Siciliano (PS) and Pecorino Toscano (PT) ewes' milk cheeses were chosen as hard cheese model systems to investigate the spatial distribution of the metabolically active microbiota and the related effects on proteolysis and synthesis of volatile components (VOC). Cheese slices were divided in nine sub-blocks, each one separately subjected to analysis and compared to whole cheese slice (control). Gradients for moisture, and concentrations of salt, fat and protein distinguished sub-blocks, while the cell density of the main microbial groups did not differ. Secondary proteolysis differed between sub-blocks of each cheese, especially when the number and area of hydrophilic and hydrophobic peptide peaks were assessed. The concentration of free amino acids (FAA) agreed with these data. As determined through Purge and Trap (PT) coupled with Gas Chromatography-Mass Spectrometry (PT-GC/MS), and regardless of the cheese variety, the profile with the lowest level of VOC was restricted to the region identified by the letter E defined as core. As shown through pyrosequencing of the 16S rRNA targeting RNA, the spatial distribution of the metabolically active microbiota agreed with the VOC distribution. Differences were highlighted between core and the rest of the cheese. Top and bottom under rind sub-blocks of all three cheeses harbored the widest biodiversity. The cheese sub-block analysis revealed the presence of a microbiota statistically correlated with secondary proteolysis events and/or synthesis of VOC. PMID:27073835

  6. In vivo gastroprotective effect along with pharmacokinetics, tissue distribution and metabolism of isoliquiritigenin in mice.

    PubMed

    Choi, Young Hee; Kim, You-Jin; Chae, Hee-Sung; Chin, Young-Won

    2015-05-01

    As numerous herbal products have been used as dietary supplements or functional foods, the demands of the pharmacokinetic and pharmacodynamic characteristics of active compounds are increasing in order to secure a consistent outcome (i.e., efficiency and safety). In this study, the pharmacokinetics including tissue distribution, metabolism, and protein binding of isoliquiritigenin, a chalcone found in Glycyrrhiza glabra, and its metabolite, liquiritigenin, at various doses in mice are reported. Also, correlations between the preferential tissue distribution and pharmacological effect of isoliquiritigenin in certain organs were investigated using the in vivo gastroprotective effect of isoliquiritigenin in mice with indomethacin-induced ulcer. The absorbed fraction of isoliquiritigenin was high, but the absolute bioavailability was low mainly due to its metabolism. In spite of the low bioavailability, the gastroprotective effect of isoliquiritigenin was attributed to its high distribution in the stomach. Isoliquiritigenin prevented the occurrence of gastric ulcers by indomethacin, which is associated with increased gastric mucous secretion because the pretreatment with isoliquiritigenin presumably counteracted the decreased cyclooxygenase 2 by indomethacin. This may suggest that the pharmacokinetic properties of isoliquiritigenin are useful to predict its efficacy as a gastroprotective agent in a target organ such as the stomach. PMID:25875506

  7. Spatial Distribution of the Metabolically Active Microbiota within Italian PDO Ewes' Milk Cheeses

    PubMed Central

    De Pasquale, Ilaria; Di Cagno, Raffaella; Buchin, Solange; De Angelis, Maria; Gobbetti, Marco

    2016-01-01

    Italian PDO (Protected Designation of Origin) Fiore Sardo (FS), Pecorino Siciliano (PS) and Pecorino Toscano (PT) ewes’ milk cheeses were chosen as hard cheese model systems to investigate the spatial distribution of the metabolically active microbiota and the related effects on proteolysis and synthesis of volatile components (VOC). Cheese slices were divided in nine sub-blocks, each one separately subjected to analysis and compared to whole cheese slice (control). Gradients for moisture, and concentrations of salt, fat and protein distinguished sub-blocks, while the cell density of the main microbial groups did not differ. Secondary proteolysis differed between sub-blocks of each cheese, especially when the number and area of hydrophilic and hydrophobic peptide peaks were assessed. The concentration of free amino acids (FAA) agreed with these data. As determined through Purge and Trap (PT) coupled with Gas Chromatography-Mass Spectrometry (PT-GC/MS), and regardless of the cheese variety, the profile with the lowest level of VOC was restricted to the region identified by the letter E defined as core. As shown through pyrosequencing of the 16S rRNA targeting RNA, the spatial distribution of the metabolically active microbiota agreed with the VOC distribution. Differences were highlighted between core and the rest of the cheese. Top and bottom under rind sub-blocks of all three cheeses harbored the widest biodiversity. The cheese sub-block analysis revealed the presence of a microbiota statistically correlated with secondary proteolysis events and/or synthesis of VOC. PMID:27073835

  8. Intramolecular stable isotope distributions detect plant metabolic responses on century time scales

    NASA Astrophysics Data System (ADS)

    Schleucher, Jürgen; Ehlers, Ina; Augusti, Angela; Betson, Tatiana

    2014-05-01

    Plants respond to environmental changes on a vast range of time scales, and plant gas exchanges constitute important feedback mechanisms in the global C cycle. Responses on time scales of decades to centuries are most important for climate models, for prediction of crop productivity, and for adaptation to climate change. Unfortunately, responses on these timescale are least understood. We argue that the knowledge gap on intermediate time scales is due to a lack of adequate methods that can bridge between short-term manipulative experiments (e.g. FACE) and paleo research. Manipulative experiments in plant ecophysiology give information on metabolism on time scales up to years. However, this information cannot be linked to results from retrospective studies in paleo research, because little metabolic information can be derived from paleo archives. Stable isotopes are prominent tools in plant ecophysiology, biogeochemistry and in paleo research, but in all applications to date, isotope ratios of whole molecules are measured. However, it is well established that stable isotope abundance varies among intramolecular groups of biochemical metabolites, that is each so-called "isotopomer" has a distinct abundance. This intramolecular variation carries information on metabolic regulation, which can even be traced to individual enzymes (Schleucher et al., Plant, Cell Environ 1999). Here, we apply intramolecular isotope distributions to study the metabolic response of plants to increasing atmospheric [CO2] during the past century. Greenhouse experiments show that the deuterium abundance among the two positions in the C6H2 group of photosynthetic glucose depends on [CO2] during growth. This is observed for all plants using C3 photosynthesis, and reflects the metabolic flux ratio between photorespiration and photosynthesis. Photorespiration is a major C flux that limits assimilation in C3 plants, which encompass the overwhelming fraction of terrestrial photosynthesis and the

  9. Transmural Distribution of Metabolic Abnormalities and Glycolytic Activity during Dobutamine Induced Demand Ischemia

    PubMed Central

    Jameel, Mohammad N; Wang, Xiaohong; Eijgelshoven, Marcel H.J.; Mansoor, Abdul; Zhang, Jianyi

    2008-01-01

    The heterogeneity across the LV wall is characterized by higher rates of oxygen consumption, systolic thickening fraction, myocardial perfusion and lower energetic state in the subendocardial layers (ENDO). During dobutamine stimulation induced demand ischemia, the transmural distribution of energy demand and metabolic markers of ischemia are not known. In this study, hemodynamics, transmural high energy phosphate (HEP) and 2-deoxyglucose-6-phosphate (2DGP) levels and myocardial blood flow (MBF) were determined under basal conditions (B), during dobutamine infusion (DOB: 20 μg/kg/min iv.), and during coronary stenosis+DOB+2-deoxy-glucose (2DG) infusion. DOB increased rate pressure products (RPP) and MBF significantly without affecting subendocardial to subepicardial blood flow ratio (ENDO/EPI) or HEP levels. During coronary stenosis+DOB+2-deoxy-glucose (2DG) infusion RPP, ischemic zone (IZ) MBF and ENDO/EPI decreased significantly. IZ PCr/ATP decreased significantly (2.30 +/- 0.14, 2.06 +/- 0.13 and 2.04 +/- 0.11 to 1.77 +/- 0.12, 1.70 +/- 0.11 and 1.72 +/- 0.12; EPI, MID and ENDO, respectively) and 2DG6P accumulated in all layers as evidenced by the 2DG6P/PCr (0.55 +/- 0.12, 0.52 +/- 0.10 and 0.37 +/- 0.08; EPI, MID and ENDO respectively; p<0.05, EPI>ENDO). In the IZ the wet weight/dry weight ratio was significantly increased as compared to the normal zone (5.9 +/- 0.5 vs. 4.4 +/- 0.4; p<0.05). Thus, in stenotic perfused bed, during dobutamine induced high cardiac workstate, despite higher blood flow the subepicardial layers showed the greater metabolic changes that characterized by a shift toward higher carbohydrate metabolism suggesting a homeostatic responses to high cardiac workstate is characterized by more glucose utilization in energy metabolism. PMID:18424629

  10. Distribution of ALA metabolic products in esophageal carcinoma cells using spectrally resolved confocal laser microscopy

    NASA Astrophysics Data System (ADS)

    Smolka, Jozef; Mateasik, Anton

    2006-08-01

    Aminolevulinic acid (ALA) is an efficient substance used in photodynamic therapy (PDT). It is a precursor of light-sensitive products that can selectively accumulate in malignant cells following the altered activity of the heme biosynthetic pathway enzymes in such cells. These products are synthesized in mitochondria and distributed to various cellular structures [1]. The localization of ALA products in subcellular structures depends on their chemical characteristics as well as on the properties of the intracellular environment [2]. Characterization of such properties is possible by means of fluorescent probes like JC-1 and carboxy SNARF-1. However, the emission spectra of these probes are overlapped with spectral pattern of typical ALA product -protoporphyrin IX (PpIX). Spectral overlap of fluorescence signals prevents to clearly separate a distribution of probes from PpIX distribution what can completely mess the applicability of these probes in characterization of cell properties. The spectrally resolved confocal laser microscopy can be used to overcome this problem. In this study, a distribution of ALA metabolic products in relation to the mitochondrial membrane potential and intracellular pH was examined. Human cell lines (KYSE-450, KYSE-70) from esophageal squamous cell carcinoma were used. Cells were incubated with 1mM solution of ALA for four hours. Two fluorescent probes, carboxy SNARF-1 and JC-1 , were used to monitor intracellular pH levels and to determine membrane potential changes, respectively. The samples were scanned by spectrally resolved laser scanning microscope. Spectral linear unmixing method was used to discriminate and separate regions of accumulation of ALA metabolic products of JC-1 and carboxy SNARF-1.

  11. Spatio-temporal Model of Xenobiotic Distribution and Metabolism in an in Silico Mouse Liver Lobule

    NASA Astrophysics Data System (ADS)

    Fu, Xiao; Sluka, James; Clendenon, Sherry; Glazier, James; Ryan, Jennifer; Dunn, Kenneth; Wang, Zemin; Klaunig, James

    Our study aims to construct a structurally plausible in silico model of a mouse liver lobule to simulate the transport of xenobiotics and the production of their metabolites. We use a physiologically-based model to calculate blood-flow rates in a network of mouse liver sinusoids and simulate transport, uptake and biotransformation of xenobiotics within the in silico lobule. Using our base model, we then explore the effects of variations of compound-specific (diffusion, transport and metabolism) and compound-independent (temporal alteration of blood flow pattern) parameters, and examine their influence on the distribution of xenobiotics and metabolites. Our simulations show that the transport mechanism (diffusive and transporter-mediated) of xenobiotics and blood flow both impact the regional distribution of xenobiotics in a mouse hepatic lobule. Furthermore, differential expression of metabolic enzymes along each sinusoid's portal to central axis, together with differential cellular availability of xenobiotics, induce non-uniform production of metabolites. Thus, the heterogeneity of the biochemical and biophysical properties of xenobiotics, along with the complexity of blood flow, result in different exposures to xenobiotics for hepatocytes at different lobular locations. We acknowledge support from National Institute of Health GM 077138 and GM 111243.

  12. The effects of microRNA on the absorption, distribution, metabolism and excretion of drugs

    PubMed Central

    He, Y; Chevillet, J R; Liu, G; Kim, T K; Wang, K

    2015-01-01

    The importance of genetic factors (e.g. sequence variation) in the absorption, distribution, metabolism, excretion (ADME) and overall efficacy of therapeutic agents is well established. Our ability to identify, interpret and utilize these factors is the subject of much clinical investigation and therapeutic development. However, drug ADME and efficacy are also heavily influenced by epigenetic factors such as DNA/histone methylation and non-coding RNAs [especially microRNAs (miRNAs)]. Results from studies using tools, such as in silico miRNA target prediction, in vitro functional assays, nucleic acid profiling/sequencing and high-throughput proteomics, are rapidly expanding our knowledge of these factors and their effects on drug metabolism. Although these studies reveal a complex regulation of drug ADME, an increased understanding of the molecular interplay between the genome, epigenome and transcriptome has the potential to provide practically useful strategies to facilitate drug development, optimize therapeutic efficacy, circumvent adverse effects, yield novel diagnostics and ultimately become an integral component of personalized medicine. PMID:25296724

  13. The role of Monosaccharide Transport Proteins in carbohydrate assimilation, distribution, metabolism and homeostasis

    PubMed Central

    Cura, Anthony J.; Carruthers, Anthony

    2012-01-01

    The facilitated diffusion of glucose, galactose, fructose, urate, myoinositol and dehydroascorbic acid in mammals is catalyzed by a family of 14 monosaccharide transport proteins called GLUTs. These transporters may be divided into 3 classes according to sequence similarity and function/substrate specificity. GLUT1 appears to be highly expressed in glycolytically active cells and has been co-opted in vitamin C auxotrophs to maintain the redox state of the blood through transport of dehydroascorbate. Several GLUTs are definitive glucose/galactose transporters, GLUT2 and GLUT5 are physiologically important fructose transporters, GLUT9 appears to be a urate transporter while GLUT13 (HMIT1) is a proton/myoinositol co-transporter. The physiologic substrates of some GLUTs remain to be established. The GLUTs are expressed in a tissue specific manner where affinity, specificity and capacity for substrate transport are paramount for tissue function. Although great strides have been made in characterizing GLUT-catalyzed monosaccharide transport and mapping GLUT membrane topography and determinants of substrate specificity, a unifying model for GLUT structure and function remains elusive. The GLUTs play a major role in carbohydrate homeostasis and the redistribution of sugar-derived carbons among the various organ systems. This is accomplished through a multiplicity of GLUT-dependent glucose sensing and effector mechanisms that regulate monosaccharide ingestion, absorption, distribution, cellular transport and metabolism and recovery/retention. Glucose transport and metabolism have co-evolved in mammals to support cerebral glucose utilization. PMID:22943001

  14. Transmural distribution of metabolic abnormalities and glycolytic activity during dobutamine-induced demand ischemia.

    PubMed

    Jameel, Mohammad N; Wang, Xiaohong; Eijgelshoven, Marcel H J; Mansoor, Abdul; Zhang, Jianyi

    2008-06-01

    The heterogeneity across the left ventricular wall is characterized by higher rates of oxygen consumption, systolic thickening fraction, myocardial perfusion, and lower energetic state in the subendocardial layers (ENDO). During dobutamine stimulation-induced demand ischemia, the transmural distribution of energy demand and metabolic markers of ischemia are not known. In this study, hemodynamics, transmural high-energy phosphate (HEP), 2-deoxyglucose-6-phosphate (2-DGP) levels, and myocardial blood flow (MBF) were determined under basal conditions, during dobutamine infusion (DOB: 20 microg x kg(-1) x min(-1) iv), and during coronary stenosis + DOB + 2-deoxyglucose (2-DG) infusion. DOB increased rate pressure products (RPP) and MBF significantly without affecting the subendocardial-to-subepicardial blood flow ratio (ENDO/EPI) or HEP levels. During coronary stenosis + DOB + 2-DG infusion, RPP, ischemic zone (IZ) MBF, and ENDO/EPI decreased significantly. The IZ ratio of creatine phosphate-to-ATP decreased significantly [2.30 +/- 0.14, 2.06 +/- 0.13, and 2.04 +/- 0.11 to 1.77 +/- 0.12, 1.70 +/- 0.11, and 1.72 +/- 0.12 for EPI, midmyocardial (MID), and ENDO, respectively], and 2-DGP accumulated in all layers, as evidenced by the 2-DGP/PCr (0.55 +/- 0.12, 0.52 +/- 0.10, and 0.37 +/- 0.08 for EPI, MID, and ENDO, respectively; P < 0.05, EPI > ENDO). In the IZ the wet weight-to-dry weight ratio was significantly increased compared with the normal zone (5.9 +/- 0.5 vs. 4.4 +/- 0.4; P < 0.05). Thus, in the stenotic perfused bed, during dobutamine-induced high cardiac work state, despite higher blood flow, the subepicardial layers showed the greater metabolic changes characterized by a shift toward higher carbohydrate metabolism, suggesting that a homeostatic response to high-cardiac work state is characterized by more glucose utilization in energy metabolism. PMID:18424629

  15. Metabolic effects and distribution space of flufenamic acid in the isolated perfused rat liver.

    PubMed

    Lopez, C H; Bracht, A; Yamamoto, N S; dos Santos, M D

    1998-11-01

    The following aspects were investigated in the present work: (a) the action of flufenamic acid on hepatic metabolism (oxygen uptake, glycolysis, gluconeogenesis, uricogenesis and glycogenolysis), (b) the action of flufenamic acid on the cellular adenine nucleotide levels, and (c) the transport and distribution space of flufenamic acid in the liver parenchyma. The experimental system was the isolated perfused rat liver. Perfusion was accomplished in an open, non-recirculating system. The perfusion fluid was Krebs/Henseleit-bicarbonate buffer (pH 7.4), saturated with a mixture of oxygen and carbon dioxide (95:5) by means of a membrane oxygenator and heated to 37 degrees C. The distribution space of flufenamic acid was measured by means of the multiple-indicator dilution technique with constant infusion (step input) of [3H]water plus flufenamic acid. The results of the present work indicate that the metabolic effects of flufenamic acid are the consequence of an uncoupling of oxidative phosphorylation, a conclusion based on the following observations: (a) flufenamic acid increased oxygen uptake, a common property of all uncouplers; (b) the drug also increased glycolysis and glycogenolysis in livers from fed rats (these are expected compensatory phenomena for the decreased mitochondrial ATP formation); (c) flufenamic acid inhibited glucose production from fructose, an energy-dependent process; (d) the cellular ATP levels were decreased by flufenamic acid whereas the AMP levels were increased; and (e) the total adenine nucleotide content was decreased by flufenamic acid and uric acid production was stimulated. Indicator-dilution experiments with flufenamic acid revealed that this substance undergoes flow-limited distribution in the liver and that its apparent distribution space greatly exceeds the aqueous space of the liver. Flufenamic acid changed its behaviour when the portal concentration was increased from 25 to 50 microM. At 25 microM the initial upslope of the

  16. In Vitro Method To Assess Soil Arsenic Metabolism by Human Gut Microbiota: Arsenic Speciation and Distribution.

    PubMed

    Yin, Naiyi; Zhang, Zhennan; Cai, Xiaolin; Du, Huili; Sun, Guoxin; Cui, Yanshan

    2015-09-01

    Arsenic (As) speciation and distribution are two important factors in assessing human health risk from As-contaminated soil. In this study, we used the combination of physiologically based extraction test (PBET) and Simulator of Human Intestinal Microbial Ecosystem (SHIME) to determine soil As metabolism by human gut microbiota. The results showed that the percentage of soil arsenate [As(V)] transformation reached 22.1-38.2%, while that of arsenite [As(III)] attained 66.5-92.0%; 30.1-56.4% of As(V) transformed was attached to the soil solid phase. In comparison to sequential extraction results, almost all amorphous Fe/Al-oxide-bound As was liberated in the colon phase. An X-ray absorption near-edge structure (XANES) showed that the As(III) percentage in the soil solid phase reached 16.6-26.9% and reached 73.4% (soil 1) in the colon phase. Additionally, plenty of As(III) and different extents of methylation were also observed in colon extraction solution. As bioaccessibility in the colon phase was 1.8-2.8 times that in the small intestinal phase. Our results indicated that human gut microbiota increased As bioaccessibility, and large amounts of As(III) were adsorbed onto the soil solid phase as a result of microbial reduction. Determining As speciation and distribution in extraction solution and soil solid phases will allow for an accurate assessment of the risk to human health upon soil As exposure. PMID:26248026

  17. Bio-distribution and metabolic paths of silica coated CdSeS quantum dots

    SciTech Connect

    Chen Zhen; Chen Hu; Meng Huan; Xing Gengmei Gao Xueyun; Sun Baoyun; Shi Xiaoli; Yuan Hui; Zhang Chengcheng; Liu Ru; Zhao Feng

    2008-08-01

    With the rapid development of quantum dot (QD) technology, water-soluble QDs have the prospect of being used as a biological probe for specific diagnoses, but their biological behaviors in vivo are little known. Our recent in vivo studies concentrated on the bio-kinetics of QDs coated by hydroxyl group modified silica networks (the QDs are 21.3 {+-} 2.0 nm in diameter and have maximal emission at 570 nm). Male ICR mice were intravenously given the water-soluble QDs with a single dose of 5 nmol/mouse. Inductively coupled plasma-mass spectrometry was used to measure the {sup 111}Cd content to indicate the concentration of QDs in plasma, organs, and excretion samples collected at predetermined time intervals. Meanwhile, the distribution and aggregation state of QDs in tissues were also investigated by pathological examination and differential centrifugation. The plasma half-life and clearance of QDs were 19.8 {+-} 3.2 h and 57.3 {+-} 9.2 ml/h/kg, respectively. The liver and kidney were the main target organs for QDs. The QDs metabolized in three paths depending on their distinct aggregated states in vivo. A fraction of free QDs, maintaining their original form, could be filtered by glomerular capillaries and excreted via urine as small molecules within five days. Most QDs bound to protein and aggregated into larger particles that were metabolized in the liver and excreted via feces in vivo. After five days, 8.6% of the injected dose of aggregated QDs still remained in hepatic tissue and it was difficult for this fraction to clear.

  18. Pharmacokinetics, distribution, metabolism, and excretion of the dual reuptake inhibitor [(14)C]-nefopam in rats.

    PubMed

    Yu, Jian; Solon, Eric; Shen, Helen; Modi, Nishit B; Mittur, Aravind

    2016-11-01

    1. This study examined the pharmacokinetics, distribution, metabolism, and excretion of [(14)C] nefopam in rats after a single oral administration. Blood, plasma, and excreta were analyzed for total radioactivity, nefopam, and metabolites. Metabolites were profiled and identified. Radioactivity distribution was determined by quantitative whole-body autoradiography. 2. The pharmacokinetic profiles of total radioactivity and nefopam were similar in male and female rats. Radioactivity partitioned approximately equally between plasma and red blood cells. A majority of the radioactivity was excreted in urine within 24 hours and mass balance was achieved within 7 days. 3. Intact nefopam was a minor component in plasma and excreta. Numerous metabolites were identified in plasma and urine generated by multiple pathways including: hydroxylation/oxidation metabolites (M11, M22a and M22b, M16, M20), some of which were further glucuronidated (M6a to M6c, M7a to M7c, M8a and M8b, M3a to M3d); N-demethylation of nefopam to metabolite M21, which additionally undergoes single or multiple hydroxylations or sulfation (M9, M14, M23), with some of the hydroxylated metabolites further glucuronidated (M2a to M2d). 4. Total radioactivity rapidly distributed with highest concentrations found in the urinary bladder, stomach, liver, kidney medulla, small intestine, uveal tract, and kidney cortex without significant accumulation or persistence. Radioactivity reversibly associated with melanin-containing tissues. PMID:26927982

  19. Can carbon surface oxidation shift the pore size distribution curve calculated from Ar, N2 and CO2 adsorption isotherms? Simulation results for a realistic carbon model

    NASA Astrophysics Data System (ADS)

    Furmaniak, Sylwester; Terzyk, Artur P.; Gauden, Piotr A.; Harris, Peter J. F.; Kowalczyk, Piotr

    2009-08-01

    Using the virtual porous carbon model proposed by Harris et al, we study the effect of carbon surface oxidation on the pore size distribution (PSD) curve determined from simulated Ar, N2 and CO2 isotherms. It is assumed that surface oxidation is not destructive for the carbon skeleton, and that all pores are accessible for studied molecules (i.e., only the effect of the change of surface chemical composition is studied). The results obtained show two important things, i.e., oxidation of the carbon surface very slightly changes the absolute porosity (calculated from the geometric method of Bhattacharya and Gubbins (BG)); however, PSD curves calculated from simulated isotherms are to a greater or lesser extent affected by the presence of surface oxides. The most reliable results are obtained from Ar adsorption data. Not only is adsorption of this adsorbate practically independent from the presence of surface oxides, but, more importantly, for this molecule one can apply the slit-like model of pores as the first approach to recover the average pore diameter of a real carbon structure. For nitrogen, the effect of carbon surface chemical composition is observed due to the quadrupole moment of this molecule, and this effect shifts the PSD curves compared to Ar. The largest differences are seen for CO2, and it is clearly demonstrated that the PSD curves obtained from adsorption isotherms of this molecule contain artificial peaks and the average pore diameter is strongly influenced by the presence of electrostatic adsorbate-adsorbate as well as adsorbate-adsorbent interactions.

  20. Can carbon surface oxidation shift the pore size distribution curve calculated from Ar, N(2) and CO(2) adsorption isotherms? Simulation results for a realistic carbon model.

    PubMed

    Furmaniak, Sylwester; Terzyk, Artur P; Gauden, Piotr A; Harris, Peter J F; Kowalczyk, Piotr

    2009-08-01

    Using the virtual porous carbon model proposed by Harris et al, we study the effect of carbon surface oxidation on the pore size distribution (PSD) curve determined from simulated Ar, N(2) and CO(2) isotherms. It is assumed that surface oxidation is not destructive for the carbon skeleton, and that all pores are accessible for studied molecules (i.e., only the effect of the change of surface chemical composition is studied). The results obtained show two important things, i.e., oxidation of the carbon surface very slightly changes the absolute porosity (calculated from the geometric method of Bhattacharya and Gubbins (BG)); however, PSD curves calculated from simulated isotherms are to a greater or lesser extent affected by the presence of surface oxides. The most reliable results are obtained from Ar adsorption data. Not only is adsorption of this adsorbate practically independent from the presence of surface oxides, but, more importantly, for this molecule one can apply the slit-like model of pores as the first approach to recover the average pore diameter of a real carbon structure. For nitrogen, the effect of carbon surface chemical composition is observed due to the quadrupole moment of this molecule, and this effect shifts the PSD curves compared to Ar. The largest differences are seen for CO(2), and it is clearly demonstrated that the PSD curves obtained from adsorption isotherms of this molecule contain artificial peaks and the average pore diameter is strongly influenced by the presence of electrostatic adsorbate-adsorbate as well as adsorbate-adsorbent interactions. PMID:21828590

  1. Tissue distribution and metabolism of guanosine in rats following intraperitoneal injection.

    PubMed

    Giuliani, P; Ballerini, P; Ciccarelli, R; Buccella, S; Romano, S; D'Alimonte, I; D' Alimonte, I; Poli, A; Beraudi, A; Peña, E; Jiang, S; Rathbone, M P; Caciagli, F; Di Iorio, P

    2012-01-01

    Guanosine has long been known as an endogenous purine nucleoside deeply involved in the modulation of several intracellular processes, especially G-protein activity. More recently, it has been reported to act as an extracellular signaling molecule released from neurons and, more markedly, from astrocytes either in basal conditions or after different kinds of stimulation including hypoxia. Moreover, in vivo studies have shown that guanosine plays an important role as both a neuroprotective and neurotrophic agent in the central nervous system. Specific high-affinity binding sites for this nucleoside have been found on membrane preparations from rat brain. The present study was undertaken to investigate the distribution and metabolic profiles of guanosine after administering the nucleoside to gain a better understanding of the biological effects of this potential drug candidate. Rats were given an intraperitonal (i.p.) injection of 2, 4, 8 or 16 mg/kg of guanosine combined with 0.05% of [3H]guanosine. Plasma samples were collected 7.5, 15, 30, 60 and 90 min after the guanosine-mixture administration and analyzed by either a liquid scintillation counter or by HPLC connected to a UV and to an on-line radiochemical detector to measure the levels of guanosine and its metabolic products guanine, xanthine and uric acid. The levels of guanosine, guanine and xanthine were also measured in brain, lung, heart, kidney and liver tissue homogenates at the defined time points after the injection of 8 mg/kg of the guanosine-mixture. We found that the levels of radioactivity in plasma increased linearly in a dose- and time-dependent manner. Guanosine was widely distributed in all tissues examined in the present study, at almost twice its usual levels. In addition, guanine levels dramatically increased in all the organs. Interestingly, enzymatic analysis of the plasma samples showed the presence of a soluble purine nucleoside phosphorylase, a key enzyme in the purine salvage pathway

  2. Anticancer efficacy and absorption, distribution, metabolism, and toxicity studies of Aspergiolide A in early drug development

    PubMed Central

    Wang, Yuanyuan; Qi, Xin; Li, Dehai; Zhu, Tianjiao; Mo, Xiaomei; Li, Jing

    2014-01-01

    Since the first anthracycline was discovered, many other related compounds have been studied in order to overcome its defects and improve efficacy. In the present paper, we investigated the anticancer effects of a new anthracycline, aspergiolide A (ASP-A), from a marine-derived fungus in vitro and in vivo, and we evaluated the absorption, distribution, metabolism, and toxicity drug properties in early drug development. We found that ASP-A had activity against topoisomerase II that was comparable to adriamycin. ASP-A decreased the growth of various human cancer cells in vitro and induced apoptosis in BEL-7402 cells via a caspase-dependent pathway. The anticancer efficacy of ASP-A on the growth of hepatocellular carcinoma xenografts was further assessed in vivo. Results showed that, compared with the vehicle group, ASP-A exhibited significant anticancer activity with less loss of body weight. A pharmacokinetics and tissue distribution study revealed that ASP-A was rapidly cleared in a first order reaction kinetics manner, and was enriched in cancer tissue. The maximal tolerable dose (MTD) of ASP-A was more than 400 mg/kg, and ASP-A was not considered to be potentially genotoxic or cardiotoxic, as no significant increase of micronucleus rates or inhibition of the hERG channel was seen. Finally, an uptake and transport assay of ASP-A was performed in monolayers of Caco-2 cells, and ASP-A was shown to be absorbed through the active transport pathway. Altogether, these results indicate that ASP-A has anticancer activity targeting topoisomerase II, with a similar structure and mechanism to adriamycin, but with much lower toxicity. Nonetheless, further molecular structure optimization is necessary. PMID:25378909

  3. The Genes and Enzymes of Phosphonate Metabolism by Bacteria, and Their Distribution in the Marine Environment

    PubMed Central

    Villarreal-Chiu, Juan F.; Quinn, John P.; McGrath, John W.

    2011-01-01

    Phosphonates are compounds that contain the chemically stable carbon–phosphorus (C–P) bond. They are widely distributed amongst more primitive life forms including many marine invertebrates and constitute a significant component of the dissolved organic phosphorus reservoir in the oceans. Virtually all biogenic C–P compounds are synthesized by a pathway in which the key step is the intramolecular rearrangement of phosphoenolpyruvate to phosphonopyruvate. However C–P bond cleavage by degradative microorganisms is catalyzed by a number of enzymes – C–P lyases, C–P hydrolases, and others of as-yet-uncharacterized mechanism. Expression of some of the pathways of phosphonate catabolism is controlled by ambient levels of inorganic P (Pi) but for others it is Pi-independent. In this report we review the enzymology of C–P bond metabolism in bacteria, and also present the results of an in silico investigation of the distribution of the genes that encode the pathways responsible, in both bacterial genomes and in marine metagenomic libraries, and their likely modes of regulation. Interrogation of currently available whole-genome bacterial sequences indicates that some 10% contain genes encoding putative pathways of phosphonate biosynthesis while ∼40% encode one or more pathways of phosphonate catabolism. Analysis of metagenomic data from the global ocean survey suggests that some 10 and 30%, respectively, of bacterial genomes across the sites sampled encode these pathways. Catabolic routes involving phosphonoacetate hydrolase, C–P lyase(s), and an uncharacterized 2-aminoethylphosphonate degradative sequence were predominant, and it is likely that both substrate-inducible and Pi-repressible mechanisms are involved in their regulation. The data we present indicate the likely importance of phosphonate-P in global biogeochemical P cycling, and by extension its role in marine productivity and in carbon and nitrogen dynamics in the oceans. PMID:22303297

  4. Theoretical study of the aluminum distribution effects on the double proton transfer mechanisms upon adsorption of 4,4'-bipyridine on H-ZSM-5.

    PubMed

    Akacem, Yamina; Castellà-Ventura, Martine; Kassab, Emile

    2012-02-01

    The aluminum distribution effects on the adsorption of 4,4'-bipyridine (44BPY) in the straight channel of H-ZSM-5 simulated by two ten-membered ring clusters (2-10T) have been investigated by DFT methods. The energetic and structural properties of the complexes formed upon interaction of 44BPY with the zeolite Brønsted acid sites for six different aluminum distributions were determined by B3LYP/6-31+G* calculations. Dispersion energies were estimated by performing single point calculations at the MP2 and M06-2X levels. Interaction energies were corrected for basis set superposition error (BSSE). The minimum energy pathways of the double proton transfer from H-ZSM-5 to 44BPY were characterized. Two mechanisms are proposed: a concerted mechanism in which both protons are simultaneously transferred giving the bidentate ion pair complex (44BPYH₂²⁺/2-10T²⁻) and a consecutive mechanism in which one proton is transferred directly leading to the monodentate ion pair complex (44BPYH⁺/2-10T⁻), whereas the second proton can be transferred according to Al distribution. The formation of monodentate or bidentate complexes strongly depends on the Al distribution. PMID:22220497

  5. Uptake, tissue distribution, and metabolism of malachite green in the channel catfish (Ictalurus punctatus)

    USGS Publications Warehouse

    Plakas, S.M.; El Said, K. R.; Stehly, G.R.; Gingerich, W.H.; Allen, J.L.

    1996-01-01

    The disposition of malachite green was determined in channel catfish (Ictalurus punctatus) after intravascular dosing (0.8 mg . Kg-1) or waterborne exposure (0.8 mg . L-1 for 1 h). After intravascular dosing, mean plasma concentrations of the parent compound exhibited a triphasic decline with a terminal elimination half-life of 6.2 h. Malachite green was rapidly absorbed and concentrated in the tissues during waterborne exposure. The rate of accumulation was directly related to pH of the exposure water. After waterborne exposure, elimination of the parent compound from plasma also was triphasic with a terminal half-life of 4.7 h. In muscle, the half-life of the parent compound was approximately 67 h. Malachite green and its metabolites were widely distributed in all tissues. In fish exposed to C-14-labeled malachite green, total drug equivalent concentrations were highest in abdominal fat and lowest in plasma. Malachite green was rapidly and extensively metabolized to its reduced form, leucomalachite green, which was slowly eliminated from the tissues. Leucomalachite green is an appropriate target analyte for monitoring exposure of channel catfish to this drug.

  6. Pharmacokinetics, tissue distribution, and metabolism of nitrofurantoin in the channel catfish (Ictalurus punctatus)

    USGS Publications Warehouse

    Stehly, G.R.; Plakas, S.M.

    1993-01-01

    The pharmacokinetics, tissue distribution, and metabolism of the drug nitrofurantoin were examined in the channel catfish (Ictalurus punctatus) after intravascular or oral dosing. Mean plasma concentrations of nitrofurantoin after intravascular administration at 1 and 10 mg/kg of body weight were best fit to two- and three-compartment pharmacokinetic models, respectively. Nitrofurantoin was rapidly eliminated from the plasma after intravascular dosing; at 1 and 10 mg/kg, the terminal half-lives were 23 and 46 min, respectively. After oral dosing at 1 mg/kg, peak plasma concentrations (0.06 mu g/ml) occurred at 2 h; the bioavailability was 17%. Residues of nitrofurantoin and its metabolites in the tissues were initially eliminated rapidly but persisted at the later sampling times. Residue concentrations were highest in the plasma and excretory tissues. Approximately 21% and 4% of the oral dose were eliminated in the urine and bile, respectively. Parent nitrofurantoin was the major radiolabelled compound found in the urine; however, the percentage of total residues composed of metabolites increased with time. Biliary residues consisted mostly of nitrofurantoin metabolites. High-performance liquid chromatography revealed the presence of at least five metabolites in the urine and bile.

  7. A computational model for the analysis of lipoprotein distributions in the mouse: translating FPLC profiles to lipoprotein metabolism.

    PubMed

    Sips, Fianne L P; Tiemann, Christian A; Oosterveer, Maaike H; Groen, Albert K; Hilbers, Peter A J; van Riel, Natal A W

    2014-05-01

    Disturbances of lipoprotein metabolism are recognized as indicators of cardiometabolic disease risk. Lipoprotein size and composition, measured in a lipoprotein profile, are considered to be disease risk markers. However, the measured profile is a collective result of complex metabolic interactions, which complicates the identification of changes in metabolism. In this study we aim to develop a method which quantitatively relates murine lipoprotein size, composition and concentration to the molecular mechanisms underlying lipoprotein metabolism. We introduce a computational framework which incorporates a novel kinetic model of murine lipoprotein metabolism. The model is applied to compute a distribution of plasma lipoproteins, which is then related to experimental lipoprotein profiles through the generation of an in silico lipoprotein profile. The model was first applied to profiles obtained from wild-type C57Bl/6J mice. The results provided insight into the interplay of lipoprotein production, remodelling and catabolism. Moreover, the concentration and metabolism of unmeasured lipoprotein components could be determined. The model was validated through the prediction of lipoprotein profiles of several transgenic mouse models commonly used in cardiovascular research. Finally, the framework was employed for longitudinal analysis of the profiles of C57Bl/6J mice following a pharmaceutical intervention with a liver X receptor (LXR) agonist. The multifaceted regulatory response to the administration of the compound is incompletely understood. The results explain the characteristic changes of the observed lipoprotein profile in terms of the underlying metabolic perturbation and resultant modifications of lipid fluxes in the body. The Murine Lipoprotein Profiler (MuLiP) presented here is thus a valuable tool to assess the metabolic origin of altered murine lipoprotein profiles and can be applied in preclinical research performed in mice for analysis of lipid fluxes and

  8. Toxicity, bio-distribution and metabolism of CO-releasing molecules based on cobalt.

    PubMed

    Gong, Yaguo; Zhang, Taofeng; Li, Meng; Xi, Na; Zheng, Yawen; Zhao, Quanyi; Chen, Yonglin; Liu, Bin

    2016-08-01

    CO-releasing molecules (CORMs) containing [Co2(CO)6] moiety show many bioactivities, such as anti-inflammatory and antitumor cell proliferation. However, so far, no one knows their properties in vivo. So, here, we evaluated some these kind CORMs from drug-like properties including cytotoxicity, toxicity in vivo, distribution and metabolism. The results show all the tested complexes displayed antiproliferative activity to HeLa cell and HepG2 cell lines, and their IC50 values were 36-110µM against HeLa cells and 39-140µM against HepG2 cells. Toxicity tests of mice, we used oral acute toxic class method and got their LD50 values; among them, LD50 of complex 1 and complex 4 were in 2500-5000mgkg(-1) and complex 7 over 5000mgkg(-1). The developmental toxicities of the complexes were investigated in embryonic zebrafish. The mortality, hatch rate, malformation, heart rate, spontaneous movement, and larval behavior were examined, and we found both complexes 4 and 7 have not toxicity at low concentration (<1.0μM) but have higher toxicity at high concentration (>5.0μM). After several consecutive i.p administrations, tested complexes severely damaged rat liver and kidney in both functional and morphological aspects. Through metal ion measurement using ICP-AES, we found the tested complexes were unevenly distributed in tissues and organs; complex 4 has a big prone to collect in liver, whereas complex 7 easily enters to kidney. After administration 480min later, most of complex 7 excreted from kidney and entered urine, while complex 4 needed 9h at least. This results show cobalt did not accumulate, and could excrete with the urine. In vivo, Co(0) in complexes was oxidised to Co(II). In addition, the substituents significantly affected the rate of CO-release, cytotoxicity and their bio-distribution. In the view of these aspects, the CORMs based cobalt has a potential property to be a medicine. PMID:27375229

  9. Potential metabolic strategies of widely distributed holobionts in the oceanic archipelago of St Peter and St Paul (Brazil).

    PubMed

    Rua, Cintia P J; Gregoracci, Gustavo B; Santos, Eidy O; Soares, Ana Carolina; Francini-Filho, Ronaldo B; Thompson, Fabiano

    2015-06-01

    Sponges are one of the most complex symbiotic communities and while the taxonomic composition of associated microbes has been determined, the biggest challenge now is to uncover their functional role in symbiosis. We investigated the microbiota of two widely distributed sponge species, regarding both their taxonomic composition and their functional roles. Samples of Didiscus oxeata and Scopalina ruetzleri were collected in the oceanic archipelago of St Peter and St Paul and analysed through metagenomics. Sequences generated by 454 pyrosequencing and Ion Torrent were taxonomically and functionally annotated on the MG-RAST server using the GenBank and SEED databases, respectively. Both communities exhibit equivalence in core functions, interestingly played by the most abundant taxa in each community. Conversely, the microbial communities differ in composition, taxonomic diversity and potential metabolic strategies. Functional annotation indirectly suggests differences in preferential pathways of carbon, nitrogen and sulphur metabolisms, which may indicate different metabolic strategies. PMID:25873456

  10. Metabolic pathway and distribution of superparamagnetic iron oxide nanoparticles: in vivo study

    PubMed Central

    Schlachter, Eva K; Widmer, Hans Ruedi; Bregy, Amadé; Lönnfors-Weitzel, Tarja; Vajtai, Istvan; Corazza, Nadia; Bernau, Vianney JP; Weitzel, Thilo; Mordasini, Pasquale; Slotboom, Johannes; Herrmann, Gudrun; Bogni, Serge; Hofmann, Heinrich; Frenz, Martin; Reinert, Michael

    2011-01-01

    Background: Experimental tissue fusion benefits from the selective heating of superparamagnetic iron oxide nanoparticles (SPIONs) under high frequency irradiation. However, the metabolic pathways of SPIONs for tissue fusion remain unknown. Hence, the goal of this in vivo study was to analyze the distribution of SPIONs in different organs by means of magnetic resonance imaging (MRI) and histological analysis after a SPION-containing patch implantation. Methods: SPION-containing patches were implanted in rats. Three animal groups were studied histologically over six months. Degradation assessment of the SPION-albumin patch was performed in vivo using MRI for iron content localization and biodistribution. Results: No SPION degradation or accumulation into the reticuloendothelial system was detected by MRI, MRI relaxometry, or histology, outside the area of the implantation patch. Concentrations from 0.01 μg/mL to 25 μg/mL were found to be hyperintense in T1-like gradient echo sequences. The best differentiation of concentrations was found in T2 relaxometry, susceptibility-sensitive gradient echo sequences, and in high repetition time T2 images. Qualitative and semiquantitative visualization of small concentrations and accumulation of SPIONs by MRI are feasible. In histological liver samples, Kupffer cells were significantly correlated with postimplantation time, but no differences were observed between sham-treated and induction/no induction groups. Transmission electron microscopy showed local uptake of SPIONs in macrophages and cells of the reticuloendothelial system. Apoptosis staining using caspase showed no increased toxicity compared with sham-treated tissue. Implanted SPION patches were relatively inert with slow, progressive local degradation over the six-month period. No distant structural alterations in the studied tissue could be observed. Conclusion: Systemic bioavailability may play a role in specific SPION implant toxicity and therefore the local

  11. Tissue distribution, metabolism and excretion of 3, 3′-dichloro-4′-sulfooxy-biphenyl in the rat

    PubMed Central

    Grimm, Fabian A.; He, Xianran; Teesch, Lynn M.; Lehmler, Hans-Joachim; Robertson, Larry W.; Duffel, Michael W.

    2015-01-01

    Polychlorinated biphenyls (PCBs) with lower numbers of chlorine atoms exhibit a greater susceptibility to metabolism than their higher-chlorinated counterparts. Following initial hydroxylation of these lower chlorinated PCBs, metabolic sulfation to form PCB sulfates is increasingly recognized as an important component of their toxicology. Since procedures for the quantitative analysis of PCB sulfates in tissue samples have not been previously available, we have now developed an efficient, LC-ESI-MS/MS based, protocol for the quantitative analysis of 4-PCB 11 sulfate in biological samples. This procedure was used to determine the distribution of 4-PCB 11 sulfate in liver, kidney, lung, and brain, as well as its excretion profile, following its intravenous administration to male Sprague-Dawley rats. Following initial uptake of 4-PCB 11 sulfate, its concentration in these tissues and serum declined within the first hour following injection. Although biliary secretion was detected, analysis of 24 hour collections of urine and feces revealed recovery of less than 4% of the administered 4-PCB 11 sulfate. High-resolution LC-MS analysis of bile, urine, and feces showed metabolic products derived from 4-PCB 11 sulfate. Thus, 4-PCB 11 sulfate at this dose was not directly excreted in the urine, but was, instead, re-distributed to tissues and/or subjected to further metabolism. PMID:26046945

  12. Distribution and Metabolism of Bt-Cry1Ac Toxin in Tissues and Organs of the Cotton Bollworm, Helicoverpa armigera

    PubMed Central

    Zhao, Zhuoya; Li, Yunhe; Xiao, Yutao; Ali, Abid; Dhiloo, Khalid Hussain; Chen, Wenbo; Wu, Kongming

    2016-01-01

    Crystal (Cry) proteins derived from Bacillus thuringiensis (Bt) have been widely used in transgenic crops due to their toxicity against insect pests. However, the distribution and metabolism of these toxins in insect tissues and organs have remained obscure because the target insects do not ingest much toxin. In this study, several Cry1Ac-resistant strains of Helicoverpa armigera, fed artificial diets containing high doses of Cry1Ac toxin, were used to investigate the distribution and metabolism of Cry1Ac in their bodies. Cry1Ac was only detected in larvae, not in pupae or adults. Also, Cry1Ac passed through the midgut into other tissues, such as the hemolymph and fat body, but did not reach the larval integument. Metabolic tests revealed that Cry1Ac degraded most rapidly in the fat body, followed by the hemolymph, peritrophic membrane and its contents. The toxin was metabolized slowly in the midgut, but was degraded in all locations within 48 h. These findings will improve understanding of the functional mechanism of Bt toxins in target insects and the biotransfer and the bioaccumulation of Bt toxins in arthropod food webs in the Bt crop ecosystem. PMID:27399776

  13. Distribution and Metabolism of Bt-Cry1Ac Toxin in Tissues and Organs of the Cotton Bollworm, Helicoverpa armigera.

    PubMed

    Zhao, Zhuoya; Li, Yunhe; Xiao, Yutao; Ali, Abid; Dhiloo, Khalid Hussain; Chen, Wenbo; Wu, Kongming

    2016-01-01

    Crystal (Cry) proteins derived from Bacillus thuringiensis (Bt) have been widely used in transgenic crops due to their toxicity against insect pests. However, the distribution and metabolism of these toxins in insect tissues and organs have remained obscure because the target insects do not ingest much toxin. In this study, several Cry1Ac-resistant strains of Helicoverpa armigera, fed artificial diets containing high doses of Cry1Ac toxin, were used to investigate the distribution and metabolism of Cry1Ac in their bodies. Cry1Ac was only detected in larvae, not in pupae or adults. Also, Cry1Ac passed through the midgut into other tissues, such as the hemolymph and fat body, but did not reach the larval integument. Metabolic tests revealed that Cry1Ac degraded most rapidly in the fat body, followed by the hemolymph, peritrophic membrane and its contents. The toxin was metabolized slowly in the midgut, but was degraded in all locations within 48 h. These findings will improve understanding of the functional mechanism of Bt toxins in target insects and the biotransfer and the bioaccumulation of Bt toxins in arthropod food webs in the Bt crop ecosystem. PMID:27399776

  14. Linking carbon and nitrogen metabolism to depth distribution of submersed macrophytes using high ammonium dosing tests and a lake survey

    PubMed Central

    Yuan, Guixiang; Cao, Te; Fu, Hui; Ni, Leyi; Zhang, Xiaolin; Li, Wei; Song, Xin; Xie, Ping; Jeppesen, Erik

    2013-01-01

    Strategies of carbon (C) and nitrogen (N) utilisation are among the factors determining plant distribution. It has been argued that submersed macrophytes adapted to lower light environments are more efficient in maintaining C metabolic homeostasis due to their conservative C strategy and ability to balance C shortage. We studied how depth distributions of 12 submersed macrophytes in Lake Erhai, China, were linked to their C-N metabolic strategies when facing acute dosing. dosing changed C-N metabolism significantly by decreasing the soluble carbohydrate (SC) content and increasing the -N and free amino acid (FAA) content of plant tissues.The proportional changes in SC contents in the leaves and FAA contents in the stems induced by dosing were closely correlated (positive for SC and negative for FAA) with the colonising water depths of the plants in Lake Erhai, the plants adapted to lower light regimes being more efficient in maintaining SC and FAA homeostasis.These results indicate that conservative carbohydrate metabolism of submersed macrophytes allowed the plants to colonise greater water depths in eutrophic lakes, where low light availability in the water column diminishes carbohydrate production by the plants. PMID:25810562

  15. A rapid kinetic dye test to predict the adsorption of 2-methylisoborneol onto granular activated carbons and to identify the influence of pore volume distributions.

    PubMed

    Greenwald, Michael J; Redding, Adam M; Cannon, Fred S

    2015-01-01

    The authors have developed a kinetic dye test protocol that aims to predict the competitive adsorption of 2-methylisoborneol (MIB) to granular activated carbons (GACs). The kinetic dye test takes about two hours to perform, and produces a quantitative result, fitted to a model to yield an Intraparticle Diffusion Constant (IDC) during the earlier times of dye sorption. The dye xylenol orange was probed into six coconut-based GACs and five bituminous-based GACs that hosted varied pore distributions. Correlations between xylenol orange IDCs and breakthrough of MIB at 4 ppt in rapid small-scale column tests (RSSCTs) were found with R²s of 0.85 and 0.95 for coconut carbons that processed waters with total organic carbon (TOCs) of 1.9 and 2.2 ppm, respectively, and with an R² of 0.94 for bituminous carbons that processed waters with a TOC of 2.5 ppm. The author sought to study the influence of the pore sizes, which provide the adsorption sites and the diffusion conduits that are necessary for the removal of those compounds. For coconut carbons, a linear correlation was established between the xylenol orange IDCs and the volume of pores in the range of 23.4-31.8 Å widths (R² = 0.98). For bituminous carbons, best correlation was to pores ranging from 74 to 93 Å widths (R² = 0.94). The differences in adsorption between coconut carbons and bituminous carbons have been attributed to the inherently dissimilar graphene layering resulting from the parent materials and the activation processes. When fluorescein dye was employed in the kinetic dye tests, the correlations to RSSCT-MIB performance were not as high as when xylenol orange was used. Intriguingly, it was the same pore size ranges that exhibited the strongest correlation for MIB RSSCT's, xylenol orange kinetics, and fluoroscein kinetics. When methylene blue dye was used, sorption occurred so rapidly as to be out of the scope of the IDC model. PMID:25462782

  16. Growth against entropy in bacterial metabolism: the phenotypic trade-off behind empirical growth rate distributions in E. coli.

    PubMed

    Martino, Daniele De; Capuani, Fabrizio; Martino, Andrea De

    2016-01-01

    The solution space of genome-scale models of cellular metabolism provides a map between physically viable flux configurations and cellular metabolic phenotypes described, at the most basic level, by the corresponding growth rates. By sampling the solution space of E. coli's metabolic network, we show that empirical growth rate distributions recently obtained in experiments at single-cell resolution can be explained in terms of a trade-off between the higher fitness of fast-growing phenotypes and the higher entropy of slow-growing ones. Based on this, we propose a minimal model for the evolution of a large bacterial population that captures this trade-off. The scaling relationships observed in experiments encode, in such frameworks, for the same distance from the maximum achievable growth rate, the same degree of growth rate maximization, and/or the same rate of phenotypic change. Being grounded on genome-scale metabolic network reconstructions, these results allow for multiple implications and extensions in spite of the underlying conceptual simplicity. PMID:27232645

  17. Growth against entropy in bacterial metabolism: the phenotypic trade-off behind empirical growth rate distributions in E. coli

    NASA Astrophysics Data System (ADS)

    De Martino, Daniele; Capuani, Fabrizio; De Martino, Andrea

    2016-06-01

    The solution space of genome-scale models of cellular metabolism provides a map between physically viable flux configurations and cellular metabolic phenotypes described, at the most basic level, by the corresponding growth rates. By sampling the solution space of E. coli's metabolic network, we show that empirical growth rate distributions recently obtained in experiments at single-cell resolution can be explained in terms of a trade-off between the higher fitness of fast-growing phenotypes and the higher entropy of slow-growing ones. Based on this, we propose a minimal model for the evolution of a large bacterial population that captures this trade-off. The scaling relationships observed in experiments encode, in such frameworks, for the same distance from the maximum achievable growth rate, the same degree of growth rate maximization, and/or the same rate of phenotypic change. Being grounded on genome-scale metabolic network reconstructions, these results allow for multiple implications and extensions in spite of the underlying conceptual simplicity.

  18. Effects of Porous Polystyrene Resin Parameters on Candida antarctica Lipase B Adsorption, Distribution, and Polyester Synthesis Activity

    SciTech Connect

    Chen,B.; Miller, M.; Gross, R.

    2007-01-01

    Polystyrene resins with varied particle sizes (35 to 350-600 {mu}m) and pore diameters (300-1000 {angstrom}) were employed to study the effects of immobilization resin particle size and pore diameter on Candida antarctica Lipase B (CALB) loading, distribution within resins, fraction of active sites, and catalytic properties for polyester synthesis. CALB adsorbed rapidly (saturation time {<=}4 min) for particle sizes 120 {mu}m (pore size = 300 {angstrom}). Infrared microspectroscopy showed that CALB forms protein loading fronts regardless of resin particle size at similar enzyme loadings ({approx}8%). From the IR images, the fractions of total surface area available to the enzyme are 21, 33, 35, 37, and 88% for particle sizes 350-600, 120, 75, 35 {mu}m (pore size 300 {angstrom}), and 35 {mu}m (pore size 1000 {angstrom}), respectively. Titration with methyl p-nitrophenyl n-hexylphosphate (MNPHP) showed that the fraction of active CALB molecules adsorbed onto resins was {approx}60%. The fraction of active CALB molecules was invariable as a function of resin particle and pore size. At {approx}8% (w/w) CALB loading, by increasing the immobilization support pore diameter from 300 to 1000 {angstrom}, the turnover frequency (TOF) of {var_epsilon}-caprolactone ({var_epsilon}-CL) to polyester increased from 12.4 to 28.2 s{sup -1}. However, the {var_epsilon}-CL conversion rate was not influenced by changes in resin particle size. Similar trends were observed for condensation polymerizations between 1,8-octanediol and adipic acid. The results herein are compared to those obtained with a similar series of methyl methacrylate resins, where variations in particle size largely affected CALB distribution within resins and catalyst activity for polyester synthesis.

  19. E-Flux2 and SPOT: Validated Methods for Inferring Intracellular Metabolic Flux Distributions from Transcriptomic Data

    PubMed Central

    Kim, Min Kyung; Lane, Anatoliy; Kelley, James J.; Lun, Desmond S.

    2016-01-01

    Background Several methods have been developed to predict system-wide and condition-specific intracellular metabolic fluxes by integrating transcriptomic data with genome-scale metabolic models. While powerful in many settings, existing methods have several shortcomings, and it is unclear which method has the best accuracy in general because of limited validation against experimentally measured intracellular fluxes. Results We present a general optimization strategy for inferring intracellular metabolic flux distributions from transcriptomic data coupled with genome-scale metabolic reconstructions. It consists of two different template models called DC (determined carbon source model) and AC (all possible carbon sources model) and two different new methods called E-Flux2 (E-Flux method combined with minimization of l2 norm) and SPOT (Simplified Pearson cOrrelation with Transcriptomic data), which can be chosen and combined depending on the availability of knowledge on carbon source or objective function. This enables us to simulate a broad range of experimental conditions. We examined E. coli and S. cerevisiae as representative prokaryotic and eukaryotic microorganisms respectively. The predictive accuracy of our algorithm was validated by calculating the uncentered Pearson correlation between predicted fluxes and measured fluxes. To this end, we compiled 20 experimental conditions (11 in E. coli and 9 in S. cerevisiae), of transcriptome measurements coupled with corresponding central carbon metabolism intracellular flux measurements determined by 13C metabolic flux analysis (13C-MFA), which is the largest dataset assembled to date for the purpose of validating inference methods for predicting intracellular fluxes. In both organisms, our method achieves an average correlation coefficient ranging from 0.59 to 0.87, outperforming a representative sample of competing methods. Easy-to-use implementations of E-Flux2 and SPOT are available as part of the open

  20. The evolution of control and distribution of adaptive mutations in a metabolic pathway.

    PubMed

    Wright, Kevin M; Rausher, Mark D

    2010-02-01

    In an attempt to understand whether it should be expected that some genes tend to be used disproportionately often by natural selection, we investigated two related phenomena: the evolution of flux control among enzymes in a metabolic pathway and properties of adaptive substitutions in pathway enzymes. These two phenomena are related by the principle that adaptive substitutions should occur more frequently in enzymes with greater flux control. Predicting which enzymes will be preferentially involved in adaptive evolution thus requires an evolutionary theory of flux control. We investigated the evolution of enzyme control in metabolic pathways with two models of enzyme kinetics: metabolic control theory (MCT) and Michaelis-Menten saturation kinetics (SK). Our models generate two main predictions for pathways in which reactions are moderately to highly irreversible: (1) flux control will evolve to be highly unequal among enzymes in a pathway and (2) upstream enzymes evolve a greater control coefficient then those downstream. This results in upstream enzymes fixing the majority of beneficial mutations during adaptive evolution. Once the population has reached high fitness, the trend is reversed, with the majority of neutral/slightly deleterious mutations occurring in downstream enzymes. These patterns are the result of three factors (the first of these is unique to the MCT simulations while the other two seem to be general properties of the metabolic pathways): (1) the majority of randomly selected, starting combinations of enzyme kinetic rates generate pathways that possess greater control for the upstream enzymes compared to downstream enzymes; (2) selection against large pools of intermediate substrates tends to prevent majority control by downstream enzymes; and (3) equivalent mutations in enzyme kinetic rates have the greatest effect on flux for enzymes with high levels of flux control, and these enzymes will accumulate adaptive substitutions, strengthening their

  1. Distributing a metabolic pathway among a microbial consortium enhances production of natural products

    PubMed Central

    Zhou, Kang; Qiao, Kangjian; Edgar, Steven; Stephanopoulos, Gregory

    2016-01-01

    Metabolic engineering of microorganisms such as Escherichia coli and Saccharomyces cerevisiae to produce high-value natural metabolites is often done through functional reconstitution of long metabolic pathways. Problems arise when parts of pathways require specialized environments or compartments for optimal function. Here we solve this problem through co-culture of engineered organisms, each of which contains the part of the pathway that it is best suited to hosting. In one example, we divided the synthetic pathway for the acetylated diol paclitaxel precursor into two modules, expressed in either S. cerevisiae or E. coli, neither of which can produce the paclitaxel precursor on their own. Stable co-culture in the same bioreactor was achieved by designing a mutualistic relationship between the two species in which a metabolic intermediate produced by E. coli was used and functionalized by yeast. This synthetic consortium produced 33 mg/L oxygenated taxanes, including a monoacetylated dioxygenated taxane. The same method was also used to produce tanshinone precursors and functionalized sesquiterpenes. PMID:25558867

  2. Absorption, tissue distribution, tissue metabolism and safety of α-mangostin in mangosteen extract using mouse models.

    PubMed

    Choi, Young Hee; Han, Seung Yon; Kim, You-Jin; Kim, Young-Mi; Chin, Young-Won

    2014-04-01

    The commercially available herbal products as the form of extract were usually mixtures containing various compounds. In spite of the purported efficacy in each active constituent, the coexisting constituents in the herbal extract might interfere with the efficacy and safety and affect the pharmacokinetic properties of active constituents. To compare for the pharmacokinetic properties of α-mangostin, a major bioactive compound, in mangosteen extract and pure α-mangostin, the pharmacokinetics as well as tissue distribution, in vitro metabolism, plasma protein binding and safety evaluation were conducted in mice because a mouse model is required a small amount of compounds and useful to develop disease models. The absorption of α-mangostin was increased and hepatic metabolism of α-mangostin was decreased in mice treated with mangosteen extract. However, the intestinal metabolism α-mangostin is comparable and still extensive in mice treated with α-mangostin and mangosteen extract. Intraperitorial LC50 of α-mangostin and mangosteen extract was 150 and 231 mg/kg, respectively. These findings may be valuable to explain the different pharmacokinetics and safety of α-mangostin and mangosteen extract. Furthermore, these findings are useful to design the efficacy and safety investigation of α-mangostin or mangosteen extract in mice with disease models or combination therapies to extrapolate into the clinical levels. PMID:24472368

  3. Distribution of Metabolically Active Prokaryotes (Archaea and Bacteria) throughout the Profiles of Chernozem and Brown Semidesert Soil

    NASA Astrophysics Data System (ADS)

    Semenov, M. V.; Manucharova, N. A.; Stepanov, A. L.

    2016-02-01

    The distribution of metabolically active cells of archaea and bacteria in the profiles of typical chernozems (Voronezh oblast) and brown semidesert soils (Astrakhan oblast) of natural and agricultural ecosystems was studied using the method of fluorescent in situ hybridization (FISH). The studied soils differed sharply in the microbial biomass and in the numbers of metabolically active cells of archaea and bacteria. The number of active bacterial cells was 3.5-7.0 times greater than that of archaea. In the arable chernozem, the numbers of active cells of archaea and bacteria were 2.6 and 1.5 times, respectively, lower than those in the chernozem under the shelterbelt. The agricultural use of the brown semidesert soil had little effect on the abundances of bacteria and archaea. The soil organic carbon content was the major factor controlling the numbers of metabolically active cells of both domains. However, the dependence of the abundance of bacteria on the organic matter content was more pronounced. The decrease in the organic carbon and total nitrogen contents down the soil profiles was accompanied by the decrease in the bacteria: archaea ratio attesting to a better adaptation of archaea to the permanent deficiency of carbon and nitrogen. The bacteria: archaea ratio can serve as an ecotrophic indicator of the state of soil microbial communities.

  4. Absorption, distribution, metabolism, and excretion of [14C]-labeled naloxegol in healthy subjects

    PubMed Central

    Bui, Khanh; She, Fahua; Hutchison, Michael; Brunnström, Åsa; Sostek, Mark

    2015-01-01

    Objective: To characterize the absorption, distribution, metabolism, and excretion of naloxegol, a PEGylated derivative of the µ-opioid antagonist naloxone, in healthy male subjects. Materials and methods: [14C]-Labeled naloxegol (27 mg, 3.43 MBq) was administered as an oral solution to 6 fasted subjects. Blood, fecal, and urine samples were collected predose and at various intervals postdose. Naloxegol and its metabolites were quantified or identified by liquid chromatography with radiometric or mass spectrometric detection. Pharmacokinetic parameters were calculated for each subject, and metabolite identification was performed by liquid chromatography with parallel radioactivity measurement and mass spectrometry. Results: Naloxegol was rapidly absorbed, with a maximum plasma concentration (geometric mean) of 51 ng/mL reached before 2 hours after dosing. A second peak in the observed naloxegol and [14C] plasma concentration-time profiles was observed at ~ 3 hours and was likely due to enterohepatic recycling of parent naloxegol. Distribution to red blood cells was negligible. Metabolism of [14C]-naloxegol was rapid and extensive and occurred via demethylation and oxidation, dealkylation, and shortening of the polyethylene glycol chain. Mean cumulative recovery of radioactivity was 84.2% of the total dose, with ~ 68.9% recovered within 96 hours of dosing. Fecal excretion was the predominant route of elimination, with mean recoveries of total radioactivity in feces and urine of 67.7% and 16.0%, respectively. Unchanged naloxegol accounted for ~ 1/4 of the radioactivity recovered in feces. Conclusions: Naloxegol was rapidly absorbed and cleared via metabolism, with predominantly fecal excretion of parent and metabolites. PMID:26329350

  5. Distribution of genetic polymorphisms of genes encoding drug metabolizing enzymes & drug transporters - a review with Indian perspective

    PubMed Central

    Umamaheswaran, Gurusamy; Kumar, Dhakchinamoorthi Krishna; Adithan, Chandrasekaran

    2014-01-01

    Phase I and II drug metabolizing enzymes (DME) and drug transporters are involved in the absorption, distribution, metabolism as well as elimination of many therapeutic agents, toxins and various pollutants. Presence of genetic polymorphisms in genes encoding these proteins has been associated with marked inter-individual variability in their activity that could result in variation in drug response, toxicity as well as in disease predisposition. The emergent field pharmacogenetics and pharmacogenomics (PGx) is a promising discipline, as it predicts disease risk, selection of proper medication with regard to response and toxicity, and appropriate drug dosage guidance based on an individual's genetic make-up. Consequently, genetic variations are essential to understand the ethnic differences in disease occurrence, development, prognosis, therapeutic response and toxicity. For that reason, it is necessary to establish the normative frequency of these genes in a particular population before unraveling the genotype-phenotype associations. Although a fair amount of allele frequency data are available in Indian populations, the existing pharmacogenetic data have not been compiled into a database. This review was intended to compile the normative frequency distribution of the variants of genes encoding DMEs (CYP450s, TPMT, GSTs, COMT, SULT1A1, NAT2 and UGTs) and transporter proteins (MDR1, OCT1 and SLCO1B1) with Indian perspective. PMID:24604039

  6. Spatial and temporal distribution of genes involved in polyamine metabolism during tomato fruit development.

    PubMed

    Tsaniklidis, Georgios; Kotsiras, Anastasios; Tsafouros, Athanasios; Roussos, Peter A; Aivalakis, Georgios; Katinakis, Panagiotis; Delis, Costas

    2016-03-01

    Polyamines are organic compounds involved in various biological roles in plants, including cell growth and organ development. In the present study, the expression profile, the accumulation of free polyamines and the transcript localisation of the genes involved in Put metabolism, such as Ornithine decarboxylase (ODC), Arginine decarboxylase (ADC) and copper containing Amine oxidase (CuAO), were examined during Solanum lycopersicum cv. Chiou fruit development and maturation. Moreover, the expression of genes coding for enzymes involved in higher polyamine metabolism, including Spermidine synthase (SPDS), Spermine synthase (SPMS), S-adenosylmethionine decarboxylase (SAMDC) and Polyamine oxidase (PAO), were studied. Most genes participating in PAs biosynthesis and metabolism exhibited an increased accumulation of transcripts at the early stages of fruit development. In contrast, CuAO and SPMS were mostly expressed later, during the development stages of the fruits where a massive increase in fruit volume occurs, while the SPDS1 gene exhibited a rather constant expression with a peak at the red ripe stage. Although Put, Spd and Spm were all exhibited decreasing levels in developing immature fruits, Put levels maxed late during fruit ripening. In contrast to Put both Spd and Spm levels continue to decrease gradually until full ripening. It is worth noticing that in situ RNA-RNA hybridisation is reported for the first time in tomato fruits. The localisation of ADC2, ODC1 and CuAO gene transcripts at tissues such as the locular parenchyma and the vascular bundles fruits, supports the theory that all genes involved in Put biosynthesis and catabolism are mostly expressed in fast growing tissues. The relatively high expression levels of CuAO at the ImG4 stage of fruit development (fruits with a diameter of 3 cm), mature green and breaker stages could possibly be attributed to the implication of polyamines in physiological processes taking place during fruit ripening. PMID

  7. A proteomics approach to the study of absorption, distribution, metabolism, excretion, and toxicity.

    PubMed

    Nordvarg, Helena; Flensburg, John; Rönn, Ola; Ohman, Johan; Marouga, Rita; Lundgren, Bo; Haid, Daniel; Malmport, Eva; Goscinski, Jan; Hörnsten, Lena; Scigelova, Michaela; Bourin, Stephanie; Garberg, Per; Woffendin, Gary; Fenyö, David; Bergling, Hélène; Forsberg, Erik

    2004-12-01

    A proteomics approach was used to identify liver proteins that displayed altered levels in mice following treatment with a candidate drug. Samples from livers of mice treated with candidate drug or untreated were prepared, quantified, labeled with CyDye DIGE Fluors, and subjected to two-dimensional electrophoresis. Following scanning and imaging of gels from three different isoelectric focusing intervals (3-10, 7-11, 6.2-7.5), automated spot handling was performed on a large number of gel spots including those found to differ more than 20% between the treated and untreated condition. Subsequently, differentially regulated proteins were subjected to a three-step approach of mass spectrometry using (a) matrix-assisted laser desorption/ionization time-of-flight mass spectrometry peptide mass fingerprinting, (b) post-source decay utilizing chemically assisted fragmentation, and (c) liquid chromatography-tandem mass spectrometry. Using this approach we have so far resolved 121 differentially regulated proteins following treatment of mice with the candidate drug and identified 110 of these using mass spectrometry. Such data can potentially give improved molecular insight into the metabolism of drugs as well as the proteins involved in potential toxicity following the treatment. The differentially regulated proteins could be used as targets for metabolic studies or as markers for toxicity. PMID:15585823

  8. Testing for bimodality in frequency distributions of data suggesting polymorphisms of drug metabolism--hypothesis testing.

    PubMed Central

    Jackson, P R; Tucker, G T; Woods, H F

    1989-01-01

    1. The theory of methods of hypothesis testing in relation to the detection of bimodality in density distributions is discussed. 2. Practical problems arising from these methods are outlined. 3. The power of three methods of hypothesis testing was compared using simulated data from bimodal distributions with varying separation between components. None of the methods could determine bimodality until the separation between components was 2 standard deviation units and could only do so reliably (greater than 90%) when the separation was as great as 4-6 standard deviation units. 4. The robustness of a parametric and a non-parametric method of hypothesis testing was compared using simulated unimodal distributions known to deviate markedly from normality. Both methods had a high frequency of falsely indicating bimodality with distributions where the components had markedly differing variances. 5. A further test of robustness using power transformation of data from a normal distribution showed that the algorithms could accurately determine unimodality only when the skew of the distribution was in the range 0-1.45. PMID:2611088

  9. Absorption, distribution, metabolism and excretion of selenium following oral administration of elemental selenium nanoparticles or selenite in rats.

    PubMed

    Loeschner, Katrin; Hadrup, Niels; Hansen, Marianne; Pereira, Sonia A; Gammelgaard, Bente; Møller, Laura Hyrup; Mortensen, Alicja; Lam, Henrik Rye; Larsen, Erik H

    2014-02-01

    A suspension of nanoparticles of BSA-stabilized red amorphous elemental selenium (Se) or an aqueous solution of sodium selenite was repeatedly administered by oral gavage for 28 days at 0.05 mg kg(-1) bw per day (low dose) or at 0.5 mg kg(-1) bw per day (high dose) as Se to female rats. Prior to administration, the size distribution of the Se nanoparticles was characterized by dynamic light scattering and transmission electron microscopy, which showed that the particles' mean diameter was 19 nm and ranged in size from 10 to 80 nm. Following administration of the high dose of Se nanoparticles or selenite the concentration of Se was determined by ICP-MS in the liver, kidney, urine, feces, stomach, lungs, and plasma at the μg g(-1) level and in brain and muscle tissue at the sub-μg g(-1) level. In order to test if any elemental Se was present in the liver, kidney or feces, an in situ derivatization selective to elemental Se was performed by treatment with sulfite, which resulted in formation of the selenosulfate anion. This Se species was selectively and quantitatively determined by anion exchange HPLC and ICP-MS detection. The results showed that elemental Se was present in the livers, kidneys and feces of animals exposed to low and high doses of elemental Se nanoparticles or to selenite, and was also detected in the same samples from control animals. The fraction of Se present as elemental Se in livers and kidneys from the high dose animals was significantly larger than the similar fraction in samples from the low dose animals or from the controls. This suggested that the natural metabolic pathways of Se were exhausted when given the high dose of elemental Se or selenite resulting in a non-metabolized pool of elemental Se. Both dosage forms of Se were bioavailable as demonstrated by the blood biomarker selenoprotein P, which was equally up-regulated in the high-dose animals for both dosage forms of Se. Finally, the excretion of Se in urine and its occurrence as Se

  10. Distribution of BPA and metabolic assessment in glioblastoma patients during BNCT treatment: a microdialysis study.

    PubMed

    Bergenheim, A Tommy; Capala, Jacek; Roslin, Michael; Henriksson, Roger

    2005-02-01

    Boron neutron capture therapy (BNCT) is dependent on the selective accumulation of boron-10 in tumour cells. To maximise the radiation effect, the neutrons should be delivered when the ratio between the boron concentration in tumour cells to that in normal tissues reaches maximum. However, the pharmacokinetics of p-boronophenylalanine (BPA) and other boron delivery agents are only partly known. We used microdialysis to investigate the extracellular in vivo kinetics of boron in three intracerebral compartments -- solid tumour, brain adjacent to tumour (BAT), and the normal brain, as well as the subcutaneous tissue before, during, and after BNCT treatment. The findings were compared to the pharmacokinetics of BPA in the blood. We also measured the glucose metabolism and the levels of glutamate and glycerol in those compartments. Four patients were studied, two patients underwent surgical tumour resection and in two a stereotactic biopsy was performed. The patients were given BPA (900 mg/kg body weight) by a 6-h infusion. The infusion was completed approximately 2-3 h before neutron irradiation. In tumour tissue the extracellular concentration of BPA followed that of blood with a maximal concentration of 31.2 ppm and a maximal ratio vs. blood of 1.07. In BAT, the maximal concentration of BPA was 18.0 ppm with the peak level delayed for 4-6 h compared to the peak in blood with a maximal ratio of 1.2. Maximal blood concentration found was 41.0 ppm. The uptake of BPA in the normal brain was considerably lower than that in the blood and tumour tissue. No change in glucose metabolism was observed. The extracellular level of glycerol was increased after treatment in tumour tissue but not in normal brain suggesting a selective acute cytotoxic effect of BNCT on tumour cells. PMID:15735919

  11. Current Approaches for Absorption, Distribution, Metabolism, and Excretion Characterization of Antibody-Drug Conjugates: An Industry White Paper.

    PubMed

    Kraynov, Eugenia; Kamath, Amrita V; Walles, Markus; Tarcsa, Edit; Deslandes, Antoine; Iyer, Ramaswamy A; Datta-Mannan, Amita; Sriraman, Priya; Bairlein, Michaela; Yang, Johnny J; Barfield, Matthew; Xiao, Guangqing; Escandon, Enrique; Wang, Weirong; Rock, Dan A; Chemuturi, Nagendra V; Moore, David J

    2016-05-01

    An antibody-drug conjugate (ADC) is a unique therapeutic modality composed of a highly potent drug molecule conjugated to a monoclonal antibody. As the number of ADCs in various stages of nonclinical and clinical development has been increasing, pharmaceutical companies have been exploring diverse approaches to understanding the disposition of ADCs. To identify the key absorption, distribution, metabolism, and excretion (ADME) issues worth examining when developing an ADC and to find optimal scientifically based approaches to evaluate ADC ADME, the International Consortium for Innovation and Quality in Pharmaceutical Development launched an ADC ADME working group in early 2014. This white paper contains observations from the working group and provides an initial framework on issues and approaches to consider when evaluating the ADME of ADCs. PMID:26669328

  12. Beyond size, ionization state, and lipophilicity: influence of molecular topology on absorption, distribution, metabolism, excretion, and toxicity for druglike compounds.

    PubMed

    Yang, Yidong; Engkvist, Ola; Llinàs, Antonio; Chen, Hongming

    2012-04-26

    The absorption, distribution, metabolism, excretion, and toxicity (ADMET) of a compound is dependent on physicochemical properties such as molecular size, lipophilicity, and ionization state. However, much less is known regarding the relationship between ADMET and the molecular topology. In this study two descriptors related to the molecular topology have been investigated, the fraction of the molecular framework (f(MF)) and the fraction of sp(3)-hybridized carbon atoms (Fsp(3)). f(MF) and Fsp(3), together with standard physicochemical properties (molecular size, ionization state, and lipophilicity), were analyzed for a set of ADMET assays. It is shown that aqueous solubility, Caco-2 permeability, plasma protein binding, human ether-a-go-go-related potassium channel protein inhibition, and CYP3A4 (CYP = cytochrome P450) inhibition are influenced by the molecular topology. These findings are in most cases independent of the already well-established relationships between the properties and molecular size, lipophilicity, and ionization state. PMID:22443161

  13. Absorption, distribution, metabolism, and excretion of macitentan, a dual endothelin receptor antagonist, in humans.

    PubMed

    Bruderer, Shirin; Hopfgartner, Gérard; Seiberling, Michael; Wank, Janine; Sidharta, Patricia N; Treiber, Alexander; Dingemanse, Jasper

    2012-09-01

    Macitentan is a tissue-targeting, dual endothelin receptor antagonist, currently under phase 3 investigation in pulmonary arterial hypertension. In this study the disposition and metabolism of macitentan were investigated following administration of a single oral 10 mg dose of (14)C-macitentan to six healthy male subjects. The total radioactivity in matrices was determined using liquid scintillation counting. The proposed structure of metabolites was based on mass spectrometry characteristics and, when available, confirmed by comparison with reference compounds. Mean (± SD) cumulative recovery of radioactivity from faeces and urine was 73.6% (± 6.2%) of the administered radioactive dose, with 49.7% (± 3.9%) cumulative recovery from urine, and 23.9% (± 4.8%) from faeces. In plasma, in addition to parent macitentan, ACT-132577, a pharmacologically active metabolite elicited by oxidative depropylation and the carboxylic acid metabolite ACT-373898 were identified. In urine, four entities were identified, with the hydrolysis product of ACT-373898 as the most abundant one. In faeces, five entities were identified, with the hydrolysis product of macitentan and ACT-132577 as the most abundant one. Concentrations of total radioactivity in whole blood were lower compared to plasma, which indicates that macitentan and its metabolites poorly bind to or penetrate into erythrocytes. PMID:22458347

  14. Absorption, distribution, metabolism, and excretion of the novel antibacterial prodrug tedizolid phosphate.

    PubMed

    Ong, Voon; Flanagan, Shawn; Fang, Edward; Dreskin, Howard J; Locke, Jeffrey B; Bartizal, Kenneth; Prokocimer, Philippe

    2014-08-01

    Tedizolid phosphate is a novel antibacterial prodrug with potent activity against Gram-positive pathogens. In vitro and in vivo studies demonstrated that the prodrug is rapidly converted by nonspecific phosphatases to the biologically active moiety tedizolid. Single oral dose radiolabeled (14)C-tedizolid phosphate kinetic studies in human subjects (100 µCi in 204 mg tedizolid phosphate free acid) confirmed a rapid time to maximum tedizolid concentration (Tmax, 1.28 hours), a long terminal half-life (10.6 hours), and a Cmax of 1.99 µg/ml. Metabolite analysis of plasma, fecal, and urine samples from rats, dogs, and humans confirmed that tedizolid is the only measurable metabolite in plasma after intravenous (in animals only) or oral administration and that tedizolid sulfate is the major metabolite excreted from the body. Excellent mass balance recovery was achieved and demonstrated that fecal excretion is the predominant (80-90%) route of elimination across species, primarily as tedizolid sulfate. Urine excretion accounted for the balance of drug elimination but contained a broader range of minor metabolites. Glucuronidation products were not detected. Similar results were observed in rats and dogs after both intravenous and oral administration. The tedizolid metabolites showed less potent antibacterial activity than tedizolid. The observations from these studies support once daily dosing of tedizolid phosphate and highlight important metabolism and excretion features that differentiate tedizolid phosphate from linezolid. PMID:24875463

  15. Nitrogen-13-labeled nitrite and nitrate: distribution and metabolism after intratracheal administration

    SciTech Connect

    Parks, N.J.; Krohn, K.A.; Mathis, C.A.; Chasko, J.H.; Geiger, K.R.; Gregor, M.E.; Peek, N.F.

    1981-04-03

    Radioactive nitrogen-13 from nitrite (NO/sub 2//sup -/) or nitrate (NO/sub 3//sup -/) administered intratracheally or intravenously without added carrier to mice or rabbits was distributed evenly throughout most organs and tissues regardless of the entry route or the anion administered. Nitrogen-13 from both anions was distributed uniformly between plasma and blood cells. Rapid in vivo oxidation of NO/sub 2//sup -/ to NO/sub 3//sup -/ at concentrations of 2 to 3 nanomoles per liter in blood was found. No reduction of /sup 13/NO/sub 3//sup -/ to /sup 13/NO/sub 2//sup -/ was observed. A mechanistic hypothesis invoking oxidation of /sup 13/NO/sub 2//sup -/ by a catalase-hydrogen peroxide complex accounts for the results.

  16. Distribution of hydrogen-metabolizing bacteria in alfalfa field soil. [Medicago sativa L. ; Convolvulus arvensis L. ; Rhizobium meliloti

    SciTech Connect

    Cunningham, S.D.; Kapulnik, Y.; Phillips, D.A.

    1986-11-01

    H/sub 2/ evolved by alfalfa root nodules during the process of N/sub 2/ fixation may be an important factor influencing the distribution of soil bacteria. To test this hypothesis under field conditions, over 700 bacterial isolates were obtained from fallow soil or from the 3-mm layer of soil surrounding alfalfa (Medicago sativa L.) root nodules, alfalfa roots, or bindweed (Convolvulus arvensis L.) roots. Bacteria were isolated under either aerobic or microaerophilic conditions and were tested for their capacity to metabolize H/sub 2/. Isolates showing net H/sub 2/ uptake and /sup 3/H/sub 2/ incorporation activity under laboratory conditions were assigned a Hup/sup +/ phenotype, whereas organisms with significant H/sub 2/ output capacity were designated as a Hout/sup +/ phenotype. Under aerobic isolation conditions two Hup/sup +/ isolates were obtained, whereas under microaerophilic conditions five Hup/sup +/ and two Hout/sup +/ isolates were found. The nine isolates differed on the basis of 24 standard bacteriological characteristics or fatty acid composition. Five of the nine organisms were isolated from soil around root nodules, whereas the other four were found distributed among the other three soil environments. On the basis of the microaerophilic isolations, 4.8% of the total procaryotic isolates from soil around root nodules were capable of oxidizing H/sub 2/, and 1.2% could produce H/sub 2/. Two of the Hup/sup +/ isolates were identified as Rhizobium meliloti by root nodulation tests, but the fact that none of the isolates reduced C/sub 2/H/sub 2/ under the assay conditions suggested that the H/sub 2/ metabolism traits were associated with various hydrogenase systems rather than with nitrogenase activity.

  17. Gastrointestinally distributed UDP-glucuronosyltransferase 1A10, which metabolizes estrogens and nonsteroidal anti-inflammatory drugs, depends upon phosphorylation.

    PubMed

    Basu, Nikhil K; Kubota, Shigeki; Meselhy, Meselhy R; Ciotti, Marco; Chowdhury, Bhabadeb; Hartori, Masao; Owens, Ida S

    2004-07-01

    Among gastrointestinal distributed isozymes encoded at the UGT1 locus, UDP-glucuronosyltransferase 1A10 (UGT1A10) metabolizes a number of important chemicals. Similar to broad conversion of phytoestrogens (Basu, N. K., Ciotti, M., Hwang, M. S., Kole, L., Mitra, P. S., Cho, J. W., and Owens, I. S. (2004) J. Biol. Chem. 279, 1429-1441), UGT1A10 metabolized estrogens and their derivatives, whereas UGT1A1, -1A3, -1A7, and -1A8 differentially exhibited reduced activity toward the same. UGT1A10 compared with UGT1A7, -1A8, and -1A3 generally exhibited high activity toward acidic nonsteroidal anti-inflammatory drugs and natural benzaldehyde derivatives, while UGT1A3 metabolized most efficiently aromatic transcinnamic acids known to be generated from flavonoid glycosides by microflora in the lower gastrointestinal tract. Finally UGT1A10, -1A7, -1A8, and -1A3 converted plant-based salicylic acids; methylsalicylic acid was transformed at high levels, and acetylsalicylic (aspirin) and salicylic acid were transformed at moderate to low levels. Atypically UGT1A10 transformed estrogens between pH 6 and 8 but acidic structures preferentially at pH 6.4. Furthermore evidence indicates UGT1A10 expressed in COS-1 cells depends upon phosphorylation; UGT1A10 versus its single, double, and triple mutants at three predicted protein kinase C phosphorylation sites incorporated [(33)P]-orthophosphate and showed a progressive decrease with no detectable label or activity for the triple T73A/T202A/S432G-1A10 mutant. Single and double mutants revealed either null/full activity or null/additive activity, respectively. Additionally UGT1A10-expressing cultures glucuronidated 17beta-[(14)C]estradiol, whereas cultures containing null mutants at protein kinase C sites showed no estrogen conversion. Importantly UGT1A10 in cells supported 10-fold higher glucuronidation of 17beta-estradiol than UGT1A1. In summary, our results suggest gastrointestinally distributed UGT1A10 is important for detoxifying

  18. Evaluation of in vitro absorption, distribution, metabolism, and excretion (ADME) properties of mitragynine, 7-hydroxymitragynine, and mitraphylline.

    PubMed

    Manda, Vamshi K; Avula, Bharathi; Ali, Zulfiqar; Khan, Ikhlas A; Walker, Larry A; Khan, Shabana I

    2014-05-01

    Mitragyna speciosa (kratom) is a popular herb in Southeast Asia, which is traditionally used to treat withdrawal symptoms associated with opiate addiction. Mitragynine, 7-hydroxymitragynine, and mitraphylline are reported to be the central nervous system active alkaloids which bind to the opiate receptors. Mitraphylline is also present in the bark of Uncaria tomentosa (cat's claw). Several therapeutic properties have been reported for these compounds but limited information is available on the absorption and distribution properties. This study focuses on evaluating the absorption, distribution, metabolism, and excretion (ADME) properties of these compounds and their effect on major efflux transporter P-glycoprotein, using in vitro methods. Quantitative analysis was performed by the Q-TOF LC-MS system. Mitragynine was unstable in simulated gastric fluid with 26 % degradation but stable in simulated intestinal fluid. 7-Hydroxymitragynine degraded up to 27 % in simulated gastric fluid, which could account for its conversion to mitragynine (23 %), while only 6 % degradation was seen in simulated intestinal fluid. Mitraphylline was stable in simulated gastric fluid but unstable in simulated intestinal fluid (13.6 % degradation). Mitragynine and 7-hydroxymitragynine showed moderate permeability across Caco-2 and MDR-MDCK monolayers with no significant efflux. However, mitraphylline was subjected to efflux mediated by P-glycoprotein in both Caco-2 and MDR-MDCK monolayers. Mitragynine was found to be metabolically stable in both human liver microsomes and S9 fractions. In contrast, both 7-hydroxymitragynine and mitraphylline were metabolized by human liver microsomes with half-lives of 24 and 50 min, respectively. All three compounds exhibited high plasma protein binding (> 90 %) determined by equilibrium dialysis. Mitragynine and 7-hydroxymitragynine inhibited P-glycoprotein with EC50 values of 18.2 ± 3.6 µM and 32.4 ± 1.9 µM, respectively

  19. Altered insulin distribution and metabolism in type I diabetics assessed by (123I)insulin scanning

    SciTech Connect

    Hachiya, H.L.; Treves, S.T.; Kahn, C.R.; Sodoyez, J.C.; Sodoyez-Goffaux, F.

    1987-04-01

    Scintigraphic scanning with (/sup 123/I)insulin provides a direct and quantitative assessment of insulin uptake and disappearance at specific organ sites. Using this technique, the biodistribution and metabolism of insulin were studied in type 1 diabetic patients and normal subjects. The major organ of (/sup 123/I)insulin uptake in both diabetic and normal subjects was the liver. After iv injection in normal subjects, the uptake of (/sup 123/I)insulin by the liver was rapid, with peak activity at 7 min. Activity declined rapidly thereafter, consistent with rapid insulin degradation and clearance. Rapid uptake of (/sup 123/I)insulin also occurred in the kidneys, although the uptake of insulin by the kidneys was about 80% of that by liver. In type 1 diabetic patients, uptake of (/sup 123/I)insulin in these organ sites was lower than that in normal subjects; peak insulin uptakes in liver and kidneys were 21% and 40% lower than those in normal subjects, respectively. The kinetics of insulin clearance from the liver was comparable in diabetic and normal subjects, whereas clearance from the kidneys was decreased in diabetics. The plasma clearance of (/sup 123/I)insulin was decreased in diabetic patients, as was insulin degradation, assessed by trichloroacetic acid precipitability. Thirty minutes after injection, 70.9 +/- 3.8% (+/- SEM) of (/sup 123/I)insulin in the plasma of diabetics was trichloroacetic acid precipitable vs. only 53.9 +/- 4.0% in normal subjects. A positive correlation was present between the organ uptake of (123I)insulin in the liver or kidneys and insulin degradation (r = 0.74; P less than 0.001).

  20. Metabolism of pyridalyl in rats: excretion, distribution, and biotransformation of dichloropropenyl-labeled pyridalyl.

    PubMed

    Nagahori, Hirohisa; Tomigahara, Yoshitaka; Isobe, Naohiko; Kaneko, Hideo

    2009-11-25

    Metabolism of pyridalyl [2,6-dichloro-4-(3,3-dichloroallyloxy)phenyl 3-[5-(trifluoromethyl)-2-pyridyloxy]propyl ether] labeled at position 2 of the dichloropropenyl group with 14C was investigated after single oral administration to male and female rats at 5 and 500 mg/kg. Absorbed 14C was excreted into feces (68-79%), urine (8-14%), and expired air (6-10%) in all of the groups. Regarding 14C-tissue residues on the seventh day after administration, fat showed the highest levels at 0.98-2.34 ppm and 219-221 ppm with the low and high doses, respectively. 14C-Residues in other tissues accounted for 0.03-0.32 ppm at the low dose and 3-70 ppm at the high dose. The percentages of the 14C-residue in fat were 1.50-3.16% of the dose, and those of muscle and hair and skin were also relatively high, accounting for 0.49-1.20%. Total 14C-residues in the whole body were 2.95-6.80% of the dose. Fecal metabolites in male rats treated with 500 mg/kg pyridalyl were purified by a combination of chromatographic techniques, and chemical structures of 8 metabolites were identified by NMR and MS spectrometry. The biotransformation reactions in rats were proposed to be as follows: (1) epoxidation of the double bond in the dichloropropenyl group followed by hydration, dehydrochlorination, decarboxylation, and/or mercapturic acid conjugation; (2) CO2 formation after O-dealkylation of pyridalyl and its metabolites; (3) hydroxylation of C3 in the pyridyl ring; (4) O-dealkylation of the pyridyloxy and the trimethylene groups; (5) dehydrochlorination and hydration in the dichloropropenyl group. PMID:19919122

  1. Adsorption of octylamine on titanium dioxide

    NASA Astrophysics Data System (ADS)

    Siwińska, Daria; Kołodziejczak-Radzimska, Agnieszka; Krysztafkiewicz, Andrzej; Jesionowski, Teofil

    2009-05-01

    Processes of adsorption and desorption of a model active substance (octylamine) on the surface of unmodified titanium dioxide (E 171) have been performed. The effects of concentration of octylamine and time of the process on the character of adsorption have been studied and the efficiency of the adsorption/desorption has been determined. The samples obtained have been studied by X-ray diffraction. The nitrogen adsorption/desorption isotherms, particle size distribution and absorption capacities of water, dibutyl phthalate and paraffin oil have been determined. The efficiency of octylamine adsorption on the surface of the titanium dioxide has been found positively correlated with the concentration of octylamine in the initial solution. The desorption of octylamine has decreased with increasing concentration of this compound adsorbed. For octylamine in low concentrations the physical adsorption has been found to dominate, which is desirable when using TiO 2 in the production of pharmaceuticals.

  2. Isothiocyanate metabolism, distribution, and interconversion in mice following consumption of thermally processed broccoli sprouts or purified sulforaphane

    PubMed Central

    Bricker, Gregory V.; Riedl, Kenneth M.; Ralston, Robin A.; Tober, Kathleen L.; Oberyszyn, Tatiana M.; Schwartz, Steven J.

    2014-01-01

    Scope Broccoli sprouts are a rich source of glucosinolates, a group of phytochemicals that when hydrolyzed, are associated with cancer prevention. Our objectives were to investigate the metabolism, distribution, and interconversion of isothiocyanates (ITCs) in mice fed thermally processed broccoli sprout powders (BSPs) or the purified ITC sulforaphane. Methods and results For 1 wk, mice were fed a control diet (n = 20) or one of four treatment diets (n = 10 each) containing nonheated BSP, 60°C mildly heated BSP, 5-min steamed BSP, or 3 mmol purified sulforaphane. Sulforaphane and erucin metabolite concentrations in skin, liver, kidney, bladder, lung, and plasma were quantified using HPLC-MS/MS. Thermal intensity of BSP processing had disparate effects on ITC metabolite concentrations upon consumption. Mild heating generally resulted in the greatest ITC metabolite concentrations in vivo, followed by the nonheated and steamed BSP diets. We observed interconversion between sulforaphane and erucin species or metabolites, and report that erucin is the favored form in liver, kidney, and bladder, even when only sulforaphane is consumed. Conclusion ITC metabolites were distributed to all tissues analyzed, suggesting the potential for systemic benefits. We report for the first time tissue-dependent ratio of sulforaphane and erucin, though further investigation is warranted to assess biological activity of individual forms. PMID:24975513

  3. The effect of partial hepatectomy on the metabolism, distribution, and nephrotoxicity of para-methylthiobenzamide in the rat.

    PubMed

    Cox, D N; Davidson, V P; Judd, C E; Stodgell, C; Traiger, G J

    1992-04-01

    Para-Methylthiobenzamide (PMTB) produces injury to the liver and kidney. Toxicity is mediated via its biotransformation to a reactive S,S-dioxide metabolite. The objective of this study was to examine the role of hepatic metabolism in the production of PMTB-induced renal toxicity. Renal injury was assessed in partially hepatectomized and sham-operated rats and the effect of this procedure on the distribution and metabolism of PMTB was examined. The in vitro oxidation of PMTB and [14C]thiobenzamide by rat kidney microsomes was also examined. Plasma urea levels and renal cortical slice uptake of organic ions were used to monitor renal function. Partial hepatectomy alone did not alter renal function nor raise blood urea nitrogen levels. Nephrotoxicity resulted when a nonnephrotoxic dose of PMTB (1.2 mmol/kg) was given to partially hepatectomized rats. An HPLC method was used for measurement of PMTB and its metabolites para-methylthiobenzamide S-oxide (PMTBSO) and para-methylbenzamide (PMBA) in plasma and kidney. Hepatectomy delayed the removal of this dose of PMTB from plasma and allowed greater concentrations of PMTB and PMTBSO to accumulate in plasma and kidney at 6 and 15 hr. The level of PMBA was similar in both groups at 6 hr, but was increased in plasma and kidney of the hepatectomized group at 15 hr. Kidney microsomes rapidly converted PMTB to PMTBSO and small amounts of PMBA. [14C]TB was oxidized by microsomes to thiobenzamide S-oxide, benzamide, and covalently bound metabolites. The results indicate that partial hepatectomy lowered the threshold for the expression of nephrotoxicity by PMTB. This procedure is associated with an increased renal accumulation of PMTB and PMTBSO, which are both sequentially transformed to the toxic metabolite. PMID:1561633

  4. Community genomic analyses constrain the distribution of metabolic traits across the Chloroflexi phylum and indicate roles in sediment carbon cycling

    PubMed Central

    2013-01-01

    Background Sediments are massive reservoirs of carbon compounds and host a large fraction of microbial life. Microorganisms within terrestrial aquifer sediments control buried organic carbon turnover, degrade organic contaminants, and impact drinking water quality. Recent 16S rRNA gene profiling indicates that members of the bacterial phylum Chloroflexi are common in sediment. Only the role of the class Dehalococcoidia, which degrade halogenated solvents, is well understood. Genomic sampling is available for only six of the approximate 30 Chloroflexi classes, so little is known about the phylogenetic distribution of reductive dehalogenation or about the broader metabolic characteristics of Chloroflexi in sediment. Results We used metagenomics to directly evaluate the metabolic potential and diversity of Chloroflexi in aquifer sediments. We sampled genomic sequence from 86 Chloroflexi representing 15 distinct lineages, including members of eight classes previously characterized only by 16S rRNA sequences. Unlike in the Dehalococcoidia, genes for organohalide respiration are rare within the Chloroflexi genomes sampled here. Near-complete genomes were reconstructed for three Chloroflexi. One, a member of an unsequenced lineage in the Anaerolinea, is an aerobe with the potential for respiring diverse carbon compounds. The others represent two genomically unsampled classes sibling to the Dehalococcoidia, and are anaerobes likely involved in sugar and plant-derived-compound degradation to acetate. Both fix CO2 via the Wood-Ljungdahl pathway, a pathway not previously documented in Chloroflexi. The genomes each encode unique traits apparently acquired from Archaea, including mechanisms of motility and ATP synthesis. Conclusions Chloroflexi in the aquifer sediments are abundant and highly diverse. Genomic analyses provide new evolutionary boundaries for obligate organohalide respiration. We expand the potential roles of Chloroflexi in sediment carbon cycling beyond

  5. Metabolic studies of neptunium in the adult baboon: retention, distribution, kinetics, and enhanced excretion by chelation therapy. Technical progress report summary

    SciTech Connect

    Not Available

    1984-01-01

    These investigations provided additional data on the uptake, distribution, retention and excretion of Np-237, Np-239 and Pa-233 in baboons following single intravenous or gavage administration. The influence of oxidation state, chemical medium, pH, mass, etc. on the metabolism of these radionuclides is related.

  6. The Human Carbon Budget: An Estimate of the Spatial Distribution of Metabolic Carbon Consumption and Release in the United States

    SciTech Connect

    West, Tristram O.; Singh, Nagendra; Marland, Gregg; Bhaduri, Budhendra L

    2009-01-01

    Carbon dioxide is taken up by agricultural crops and released soon after during the consumption of agricultural commodities. The global net impact of this process on carbon flux to the atmosphere is negligible, but impact on the spatial distribution of carbon dioxide uptake and release across regions and continents is significant. To estimate the consumption and release of carbon by humans over the landscape, we developed a carbon budget for humans in the United States. The budget was derived from food commodity intake data for the US and from algorithms representing the metabolic processing of carbon by humans. Data on consumption, respiration, and waste of carbon by humans were distributed over the US using geospatial population data with a resolution of approximately 450 x 450 m. The average adult in the US contains about 21 kg C and consumes about 67 kg C yr-1 which is balanced by the annual release of about 59 kg C as expired CO2, 7 kg C as feces and urine, and less than 1 kg C as flatus, sweat, and aromatic compounds. In 2000, an estimated 17.2 Tg C were consumed by the US population and 15.2 Tg C were expired to the atmosphere as CO2. Historically, carbon stock in the US human population has increased between 1790-2006 from 0.06 Tg to 5.37 Tg. Displacement and release of total harvested carbon per capita in the US is nearly 12% of per capita fossil fuel emissions. Humans are using, storing, and transporting carbon about the Earth s surface. Inclusion of these carbon dynamics in regional carbon budgets can improve our understanding of carbon sources and sinks.

  7. Epicardial fat thickness: distribution and association with diabetes mellitus, hypertension and the metabolic syndrome in the ELSA-Brasil study.

    PubMed

    Graeff, Daniela Bertol; Foppa, Murilo; Pires, Julio Cesar Gall; Vigo, Alvaro; Schmidt, Maria Ines; Lotufo, Paulo Andrade; Mill, Jose Geraldo; Duncan, Bruce Bartholow

    2016-04-01

    Epicardial fat thickness (EFT) has emerged as a marker of cardiometabolic risk, but its clinical use warrants proper knowledge of its distribution and associations in populations. We aimed to describe the distribution of EFT, its demographic correlates and independent associations with diabetes, hypertension and metabolic syndrome (MS) in free-living Brazilian adults. From the baseline echocardiography of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)-a cohort study of civil servants aged 35-74 years-EFT was measured from a randomly selected sample of 998 participants as the mean of two paraesternal windows obtained at end systole (EFTsyst) and end diastole (EFTdiast). From the 421 individuals free of diabetes, hypertension and MS, we defined EFT reference values and the EFTsyst 75th percentile cut-off. Median EFTsyst was 1.5 (IQR 0-2.6) mm; a large proportion (84 %) had EFTdiast = 0. EFT was higher in women and lower in blacks, and increased with age and BMI. Although EFT was higher in those with diabetes, hypertension, and MS, EFT associations were reduced when adjusted for age, sex and ethnicity, and were non-significant after adjusting for obesity measures. In conclusion, the amount of EFT in this large multiethnic population is smaller than reported in other populations. EFT reference values varied across demographic and clinical variables, EFT associations with cardiometabolic variables being largely explained by age, sex, ethnicity and central obesity. Although EFT can help identify individuals at increased cardiometabolic risk, it will likely have a limited additional role compared to current risk stratification strategies. PMID:26585750

  8. The chemostat study of metabolic distribution in extreme-thermophilic (70°C) mixed culture fermentation.

    PubMed

    Zhang, Fang; Chen, Yun; Dai, Kun; Zeng, Raymond J

    2014-12-01

    The effects of pH, hydrogen partial pressure (PH2), and influent glucose concentration on the metabolic distribution in chemostat were investigated in this work in extreme-thermophilic mixed culture fermentation (MCF) process. The results showed that acetate, ethanol, and hydrogen were the main metabolites. A shift of ethanol to acetate and hydrogen was observed as pH increasing from 4.0 to 7.0 or PH2 decreasing from 0.64 to 0.05 atm. The maximum hydrogen yield was 3.16 ± 0.16 mol/mol glucose at PH2 0.05 atm. Lactate was only accumulated at low pH or high influent glucose concentration, while others such as butyrate and formate were rather low. Thermodynamic analysis illustrated that a mixture of acetate, ethanol, and/or lactate was essential for hydrogen production in extreme-thermophilic MCF. The hydrogen-producing rate was also calculated, and the maximum value was 2.2 ± 0.1 L/(L-reactor/day) at PH2 0.05 atm. Except hydrogen, other metabolites, such as liquid fatty acids and biofuels, could also be the producing targets in extreme-thermophilic MCF. PMID:25341404

  9. What do metabolic rates tell us about thermal niches? Mechanisms driving crayfish distributions along an altitudinal gradient.

    PubMed

    Stoffels, Rick J; Richardson, Adam J; Vogel, Matthew T; Coates, Simon P; Müller, Warren J

    2016-01-01

    Humans are rapidly altering thermal landscapes, so a central challenge to organismal ecologists is to better understand the thermal niches of ectotherms. However, there is much disagreement over how we should go about this. Some ecologists assume that a statistical model of abundance as a function of habitat temperature provides a sufficient approximation of the thermal niche, but ecophysiologists have shown that the relationship between fitness and temperature can be complicated, and have stressed the need to elucidate the causal mechanisms underlying the response of species to thermal change. Towards this end, we studied the distribution of two crayfishes, Euastacus woiwuru and Euastacus armatus, along an altitudinal gradient, and for both species conducted experiments to determine the temperature-dependence of: (1) aerobic scope (the difference between maximum and basal metabolic rate; purported to be a proxy of the thermal niche); and (2) burst locomotor performance (primarily fuelled using anaerobic pathways). E. woiwuru occupied cooler habitats than E. armatus, but we found no difference in aerobic scope between these species. In contrast, locomotor performance curves differed significantly and strongly between species, with peak locomotor performances of E. woiwuru and E. armatus occurring at ~10 and ~18 °C, respectively. Crayfish from different thermal landscapes may have similar aerobic thermal performance curves but different anaerobic thermal performance curves. Our results support a growing body of literature implying different components of ectotherm fitness have different thermal performance curves, and further challenge our understanding of the ecology and evolution of thermal niches. PMID:26440800

  10. Niche and metabolic principles explain patterns of diversity and distribution: theory and a case study with soil bacterial communities.

    PubMed

    Okie, Jordan G; Van Horn, David J; Storch, David; Barrett, John E; Gooseff, Michael N; Kopsova, Lenka; Takacs-Vesbach, Cristina D

    2015-06-22

    The causes of biodiversity patterns are controversial and elusive due to complex environmental variation, covarying changes in communities, and lack of baseline and null theories to differentiate straightforward causes from more complex mechanisms. To address these limitations, we developed general diversity theory integrating metabolic principles with niche-based community assembly. We evaluated this theory by investigating patterns in the diversity and distribution of soil bacteria taxa across four orders of magnitude variation in spatial scale on an Antarctic mountainside in low complexity, highly oligotrophic soils. Our theory predicts that lower temperatures should reduce taxon niche widths along environmental gradients due to decreasing growth rates, and the changing niche widths should lead to contrasting α- and β-diversity patterns. In accord with the predictions, α-diversity, niche widths and occupancies decreased while β-diversity increased with increasing elevation and decreasing temperature. The theory also successfully predicts a hump-shaped relationship between α-diversity and pH and a negative relationship between α-diversity and salinity. Thus, a few simple principles explained systematic microbial diversity variation along multiple gradients. Such general theory can be used to disentangle baseline effects from more complex effects of temperature and other variables on biodiversity patterns in a variety of ecosystems and organisms. PMID:26019154

  11. Tissue Distributions of Dhurrin and of Enzymes Involved in Its Metabolism in Leaves of Sorghum bicolor1

    PubMed Central

    Kojima, Mineo; Poulton, Jonathan E.; Thayer, Susan S.; Conn, Eric E.

    1979-01-01

    The tissue distributions of dhurrin [p-hydroxy-(S)-mandelonitrile-β-d-glucoside] and of enzymes involved in its metabolism have been investigated in leaf blades of light-grown Sorghum bicolor seedlings. Enzymic digestion of these leaves using cellulase has enabled preparations of epidermal and mesophyll protoplasts and bundle sheath strands to be isolated with only minor cross-contamination. Dhurrin was located entirely in the epidermal layers of the leaf blade, whereas the two enzymes responsible for its catabolism, namely dhurrin β-glucosidase and hydroxynitrile lyase, resided almost exclusively in the mesophyll tissue. The final enzyme of dhurrin biosynthesis, uridine diphosphate glucose:p-hydroxymandelonitrile glucosyltransferase, was found in both mesophyll (32% of the total activity of the leaf blade) and epidermal (68%) tissues. The bundle sheath strands did not contain significant amounts of dhurrin or of these enzymes. It was concluded that the separation of dhurrin and its catabolic enzymes in different tissues prevents its large scale hydrolysis under normal physiological conditions. The well documented production of HCN (cyanogenesis), which occurs rapidly on crushing Sorghum leaves, would be expected to proceed when the contents of the ruptured epidermal and mesophyll cells are allowed to mix. Images PMID:16660850

  12. Changes in Angiotensin Receptor Distribution and in Aortic Morphology Are Associated with Blood Pressure Control in Aged Metabolic Syndrome Rats

    PubMed Central

    Guarner-Lans, Verónica; Soria-Castro, Elizabeth; Torrico-Lavayen, Rocío; Patrón-Soberano, Araceli; Carvajal-Aguilera, Karla G.; Castrejón-Tellez, Vicente; Rubio-Ruiz, María Esther

    2016-01-01

    The role of the renin-angiotensin system (RAS) in blood pressure regulation in MS during aging is unknown. It participates in metabolic syndrome (MS) and aging regulating vascular tone and remodeling. RAS might participate in a compensatory mechanism decreasing blood pressure and allowing MS rats to reach 18 months of age and it might form part of therapeutical procedures to ameliorate MS. We studied histological changes and distribution of RAS receptors in aortas of MS aged rats. Electron microscopy images showed premature aging in MS since the increased fibrosis, enlarged endothelium, and invasion of this layer by muscle cells that was present in control 18-month-old aortas were also found in 6-month-old aortas from MS rats. AT1, AT2, and Mas receptors mediate the effects of Ang II and Ang 1-7, respectively. Fluorescence from AT2 decreased with age in control and MS aortas, while fluorescence of AT1 increased in aortas from MS rats at 6 months and diminished during aging. Mas expression increased in MS rats and remained unchanged in control rats. In conclusion, there is premature aging in the aortas from MS rats and the elevated expression of Mas receptor might contribute to decrease blood pressure during aging in MS. PMID:27293881

  13. An impaired metabolic response to hydrostatic pressure explains Alcanivorax borkumensis recorded distribution in the deep marine water column

    PubMed Central

    Scoma, Alberto; Barbato, Marta; Borin, Sara; Daffonchio, Daniele; Boon, Nico

    2016-01-01

    Alcanivorax borkumensis is an ubiquitous model organism for hydrocarbonoclastic bacteria, which dominates polluted surface waters. Its negligible presence in oil-contaminated deep waters (as observed during the Deepwater Horizon accident) raises the hypothesis that it may lack adaptive mechanisms to hydrostatic pressure (HP). The type strain SK2 was tested under 0.1, 5 and 10 MPa (corresponding to surface water, 500 and 1000 m depth, respectively). While 5 MPa essentially inactivated SK2, further increase to 10 MPa triggered some resistance mechanism, as indicated by higher total and intact cell numbers. Under 10 MPa, SK2 upregulated the synthetic pathway of the osmolyte ectoine, whose concentration increased from 0.45 to 4.71 fmoles cell−1. Central biosynthetic pathways such as cell replication, glyoxylate and Krebs cycles, amino acids metabolism and fatty acids biosynthesis, but not β-oxidation, were upregulated or unaffected at 10 MPa, although total cell number was remarkably lower with respect to 0.1 MPa. Concomitantly, expression of more than 50% of SK2 genes was downregulated, including genes related to ATP generation, respiration and protein translation. Thus, A. borkumensis lacks proper adaptation to HP but activates resistance mechanisms. These consist in poorly efficient biosynthetic rather than energy-yielding degradation-related pathways, and suggest that HP does represent a major driver for its distribution at deep-sea. PMID:27515484

  14. An impaired metabolic response to hydrostatic pressure explains Alcanivorax borkumensis recorded distribution in the deep marine water column.

    PubMed

    Scoma, Alberto; Barbato, Marta; Borin, Sara; Daffonchio, Daniele; Boon, Nico

    2016-01-01

    Alcanivorax borkumensis is an ubiquitous model organism for hydrocarbonoclastic bacteria, which dominates polluted surface waters. Its negligible presence in oil-contaminated deep waters (as observed during the Deepwater Horizon accident) raises the hypothesis that it may lack adaptive mechanisms to hydrostatic pressure (HP). The type strain SK2 was tested under 0.1, 5 and 10 MPa (corresponding to surface water, 500 and 1000 m depth, respectively). While 5 MPa essentially inactivated SK2, further increase to 10 MPa triggered some resistance mechanism, as indicated by higher total and intact cell numbers. Under 10 MPa, SK2 upregulated the synthetic pathway of the osmolyte ectoine, whose concentration increased from 0.45 to 4.71 fmoles cell(-1). Central biosynthetic pathways such as cell replication, glyoxylate and Krebs cycles, amino acids metabolism and fatty acids biosynthesis, but not β-oxidation, were upregulated or unaffected at 10 MPa, although total cell number was remarkably lower with respect to 0.1 MPa. Concomitantly, expression of more than 50% of SK2 genes was downregulated, including genes related to ATP generation, respiration and protein translation. Thus, A. borkumensis lacks proper adaptation to HP but activates resistance mechanisms. These consist in poorly efficient biosynthetic rather than energy-yielding degradation-related pathways, and suggest that HP does represent a major driver for its distribution at deep-sea. PMID:27515484

  15. CeCaFDB: a curated database for the documentation, visualization and comparative analysis of central carbon metabolic flux distributions explored by 13C-fluxomics.

    PubMed

    Zhang, Zhengdong; Shen, Tie; Rui, Bin; Zhou, Wenwei; Zhou, Xiangfei; Shang, Chuanyu; Xin, Chenwei; Liu, Xiaoguang; Li, Gang; Jiang, Jiansi; Li, Chao; Li, Ruiyuan; Han, Mengshu; You, Shanping; Yu, Guojun; Yi, Yin; Wen, Han; Liu, Zhijie; Xie, Xiaoyao

    2015-01-01

    The Central Carbon Metabolic Flux Database (CeCaFDB, available at http://www.cecafdb.org) is a manually curated, multipurpose and open-access database for the documentation, visualization and comparative analysis of the quantitative flux results of central carbon metabolism among microbes and animal cells. It encompasses records for more than 500 flux distributions among 36 organisms and includes information regarding the genotype, culture medium, growth conditions and other specific information gathered from hundreds of journal articles. In addition to its comprehensive literature-derived data, the CeCaFDB supports a common text search function among the data and interactive visualization of the curated flux distributions with compartmentation information based on the Cytoscape Web API, which facilitates data interpretation. The CeCaFDB offers four modules to calculate a similarity score or to perform an alignment between the flux distributions. One of the modules was built using an inter programming algorithm for flux distribution alignment that was specifically designed for this study. Based on these modules, the CeCaFDB also supports an extensive flux distribution comparison function among the curated data. The CeCaFDB is strenuously designed to address the broad demands of biochemists, metabolic engineers, systems biologists and members of the -omics community. PMID:25392417

  16. Arsenic Adsorption Equilibrium Concentration and Adsorption Rate of Activated Carbon Coated with Ferric-Aluminum Hydroxides

    NASA Astrophysics Data System (ADS)

    Zhang, M.; Sugita, H.; Oguma, T.; Hara, J.; Takahashi, S.

    2015-12-01

    In some areas of developing countries, ground or well water contaminated with arsenic has been reluctantly used as drinking water. It is highly desirable that effective and inexpensive arsenic removal agents should be developed and provided to reduce the potential health risk. Previous studies demonstrated that activated carbon coated with ferric-aluminum hydroxides (Fe-Al-C) has high adsorptive potential for removal of arsenic. In this study, a series of experiments using Fe-Al-C were carried to discuss adsorption equilibrium time, adsorption equilibrium concentration and adsorption rate of arsenic for Fe-Al-C. Fe-Al-C used in this study was provided by Astec Co., Ltd. Powder reagent of disodium hydrogen arsenate heptahydrate was dissolved into ion-exchanged water. The solution was then further diluted with ion-exchanged water to be 1 and 10 mg/L as arsenic concentration. The pH of the solution was adjusted to be around 7 by adding HCl and/or NaOH. The solution was used as artificial arsenic contaminated water in two types of experiments (arsenic adsorption equilibrium and arsenic adsorption rate tests). The results of the arsenic equilibrium tests were showed that a time period of about 3 days to reach apparent adsorption equilibrium for arsenic. The apparent adsorption equilibrium concentration and adsorbed amount of arsenic on Fe-Al-C adsorbent could be estimated by application of various adsorption isotherms, but the distribution coefficient of arsenic between solid and liquid varies with experimental conditions such as initial concentration of arsenic and addition concentration of adsorbent. An adsorption rate equation that takes into account the reduction in the number of effective adsorption sites on the adsorbent caused by the arsenic adsorption reaction was derived based on the data obtained from the arsenic adsorption rate tests.

  17. Adsorption in sparse networks. 2: Silica aerogels

    SciTech Connect

    Scherer, G.W.; Calas, S.; Sempere, R.

    1998-06-15

    The model developed in Part 1 is applied to nitrogen adsorption isotherms obtained for a series of silica aerogels whose densities are varied by partial sintering. The isotherms are adequately described by a cubic network model, with all of the pores falling in the mesopore range; the adsorption and desorption branches are fit by the same pore size distribution. For the least dense gels, a substantial portion of the pore volume is not detected by condensation. The model attributes this effect to the shape of the adsorbate/adsorptive interface, which can adopt zero curvature even in mesopores, because of the shape of the network.

  18. Metabolic flux distributions in Corynebacterium glutamicum during growth and lysine overproduction. Reprinted from Biotechnology and Bioengineering, Vol. 41, Pp 633-646 (1993).

    PubMed

    Vallino, J J; Stephanopoulos, G

    2000-03-20

    The two main contributions of this article are the solidification of Corynebacterium glutamicum biochemistry guided by bioreaction network analysis, and the determination of basal metabolic flux distributions during growth and lysine synthesis. Employed methodology makes use of stoichiometrically based mass balances to determine flux distributions in the C. glutamicum metabolic network. Presented are a brief description of the methodology, a thorough literature review of glutamic acid bacteria biochemistry, and specific results obtained through a combination of fermentation studies and analysis-directed intracellular assays. The latter include the findings of the lack of activity of glyoxylate shunt, and that phosphoenolpyruvate carboxylase (PPC) is the only anaplerotic reaction expressed in C. glutamicum cultivated on glucose minimal media. Network simplifications afforded by the above findings facilitated the determination of metabolic flux distributions under a variety of culture conditions and led to the following conclusions. Both the pentose phosphate pathway and PPC support significant fluxes during growth and lysine overproduction, and that flux partitioning at the glucosa-6-phosphate branch point does not appear to limit lysine synthesis. PMID:10699864

  19. Enhancement in ion adsorption rate and desalination efficiency in a capacitive deionization cell through improved electric field distribution using electrodes composed of activated carbon cloth coated with zinc oxide nanorods.

    PubMed

    Laxman, Karthik; Myint, Myo Tay Zar; Bourdoucen, Hadj; Dutta, Joydeep

    2014-07-01

    Electrodes composed of activated carbon cloth (ACC) coated with zinc oxide (ZnO) nanorods are compared with plain ACC electrodes, with respect to their desalination efficiency of a 17 mM NaCl solution at different applied potentials. Polarization of the ZnO nanorods increased the penetration depth and strength of the electric field between the electrodes, leading to an increase in the capacitance and charge efficiency at reduced input charge ratios. Uniform distribution of the electric field lines between two electrodes coated with ZnO nanorods led to faster ion adsorption rates, reduced the electrode saturation time, and increased the average desalination efficiency by ∼45% for all applied potentials. The electrodes were characterized for active surface area, capacitance from cyclic voltammetry, theoretical assessment of surface area utilization, and the magnitude of electric field force acting on an ion of unit charge for each potential. PMID:24940607

  20. Adsorption characteristics of siloxanes in landfill gas by the adsorption equilibrium test

    SciTech Connect

    Nam, Sangchul; Namkoong, Wan; Kang, Jeong-Hee; Park, Jin-Kyu; Lee, Namhoon

    2013-10-15

    Highlights: • Equilibrium test was attempted to evaluate adsorption characteristics of siloxane. • L2 had higher removal efficiency in carbon compared to noncarbon adsorbents. • Total adsorption capacity of siloxane was 300 mg/g by coal activated carbon. • Adsorption characteristics rely on size of siloxane molecule and adsorbent pore. • Conversion of siloxane was caused by adsorption of noncarbon adsorbents. - Abstract: Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane.

  1. Proton and Cd adsorption onto natural bacterial consortia: Testing universal adsorption behavior

    NASA Astrophysics Data System (ADS)

    Borrok, David; Fein, Jeremy B.; Kulpa, Charles F.

    2004-08-01

    Bacterial surface adsorption can control metal distributions in some natural systems, yet it is unclear whether natural bacterial consortia differ in their adsorption behaviors. In this study, we conduct potentiometric titration and metal adsorption experiments to measure proton and Cd adsorption onto a range of bacterial consortia. We model the experimental data using a surface complexation approach to determine thermodynamic stability constants. Our results indicate that these consortia adsorb similar extents of protons and Cd and that the adsorption onto all of the consortia can be modeled using a single set of stability constants. Consortia of bacteria cultured from natural environments also adsorb metals to lesser extents than individual strains of laboratory-cultivated species. This study suggests that a wide range of bacterial species exhibit similar adsorption behaviors, potentially simplifying the task of modeling the distribution and speciation of metals in bacteria-bearing natural systems. Current models for bacteria-metal adsorption that rely on pure strains of laboratory-cultivated species likely overpredict the amount of bacteria-metal adsorption in natural systems.

  2. Exploring in vitro, in vivo metabolism of mogroside V and distribution of its metabolites in rats by HPLC-ESI-IT-TOF-MS(n).

    PubMed

    Xu, Feng; Li, Dian-Peng; Huang, Zhen-Cong; Lu, Feng-Lai; Wang, Lei; Huang, Yong-Lin; Wang, Ru-Feng; Liu, Guang-Xue; Shang, Ming-Ying; Cai, Shao-Qing

    2015-11-10

    Mogroside V, a cucurbitane-type saponin, is not only the major bioactive constituent of traditional Chinese medicine Siraitiae Fructus, but also a widely used sweetener. To clarify its biotransformation process and identify its effective forms in vivo, we studied its metabolism in a human intestinal bacteria incubation system, a rat hepatic 9000g supernatant (S9) incubation system, and rats. Meanwhile, the distribution of mogroside V and its metabolites was also reported firstly. Seventy-seven new metabolites, including 52 oxidation products formed by mono- to tetra- hydroxylation/dehydrogenation, were identified with the aid of HPLC in tandem with ESI ion trap (IT) TOF multistage mass spectrometry (HPLC-ESI-IT-TOF-MS(n)). Specifically, 14 metabolites were identified in human intestinal bacteria incubation system, 4 in hepatic S9 incubation system, 58 in faeces, 29 in urine, 14 in plasma, 34 in heart, 33 in liver, 39 in spleen, 39 in lungs, 42 in kidneys, 45 in stomach, and 51 in small intestine. The metabolic pathways of mogroside V were proposed and the identified metabolic reactions were deglycosylation, hydroxylation, dehydrogenation, isomerization, glucosylation, and methylation. Mogroside V and its metabolites were distributed unevenly in the organs of treated rats. Seven bioactive metabolites of mogroside V were identified, among which mogroside IIE was abundant in heart, liver, spleen and lung, suggesting that it may contribute to the bioactivities of mogroside V. Mogroside V was mainly excreted in urine, whereas its metabolites were mainly excreted in faeces. To our knowledge, this is the first report that a plant constituent can be biotransformed into more than 65 metabolites in vivo. These findings will improve understanding of the in vivo metabolism, distribution, and effective forms of mogroside V and congeneric molecules. PMID:26280925

  3. Pyruvate kinase and aspartate-glutamate carrier distributions reveal key metabolic links between neurons and glia in retina

    PubMed Central

    Lindsay, Ken J.; Du, Jianhai; Sloat, Stephanie R.; Contreras, Laura; Linton, Jonathan D.; Turner, Sally J.; Sadilek, Martin; Hurley, James B.

    2014-01-01

    Symbiotic relationships between neurons and glia must adapt to structures, functions, and metabolic roles of the tissues they are in. We show here that Müller glia in retinas have specific enzyme deficiencies that can enhance their ability to synthesize Gln. The metabolic cost of these deficiencies is that they impair the Müller cell’s ability to metabolize Glc. We show here that the cells can compensate for this deficiency by using metabolites produced by neurons. Müller glia are deficient for pyruvate kinase (PK) and for aspartate/glutamate carrier 1 (AGC1), a key component of the malate-aspartate shuttle. In contrast, photoreceptor neurons express AGC1 and the M2 isoform of pyruvate kinase, which is commonly associated with aerobic glycolysis in tumors, proliferating cells, and some other cell types. Our findings reveal a previously unidentified type of metabolic relationship between neurons and glia. Müller glia compensate for their unique metabolic adaptations by using lactate and aspartate from neurons as surrogates for their missing PK and AGC1. PMID:25313047

  4. Carbon-Flux Distribution within Streptomyces coelicolor Metabolism: A Comparison between the Actinorhodin-Producing Strain M145 and Its Non-Producing Derivative M1146

    PubMed Central

    Coze, Fabien; Gilard, Françoise; Tcherkez, Guillaume; Virolle, Marie-Joëlle; Guyonvarch, Armel

    2013-01-01

    Metabolic Flux Analysis is now viewed as essential to elucidate the metabolic pattern of cells and to design appropriate genetic engineering strategies to improve strain performance and production processes. Here, we investigated carbon flux distribution in two Streptomyces coelicolor A3 (2) strains: the wild type M145 and its derivative mutant M1146, in which gene clusters encoding the four main antibiotic biosynthetic pathways were deleted. Metabolic Flux Analysis and 13C-labeling allowed us to reconstruct a flux map under steady-state conditions for both strains. The mutant strain M1146 showed a higher growth rate, a higher flux through the pentose phosphate pathway and a higher flux through the anaplerotic phosphoenolpyruvate carboxylase. In that strain, glucose uptake and the flux through the Krebs cycle were lower than in M145. The enhanced flux through the pentose phosphate pathway in M1146 is thought to generate NADPH enough to face higher needs for biomass biosynthesis and other processes. In both strains, the production of NADPH was higher than NADPH needs, suggesting a key role for nicotinamide nucleotide transhydrogenase for redox homeostasis. ATP production is also likely to exceed metabolic ATP needs, indicating that ATP consumption for maintenance is substantial.Our results further suggest a possible competition between actinorhodin and triacylglycerol biosynthetic pathways for their common precursor, acetyl-CoA. These findings may be instrumental in developing new strategies exploiting S. coelicolor as a platform for the production of bio-based products of industrial interest. PMID:24376790

  5. Adsorption Refrigeration System

    SciTech Connect

    Wang, Kai; Vineyard, Edward Allan

    2011-01-01

    Adsorption refrigeration is an environmentally friendly cooling technology which could be driven by recovered waste heat or low-grade heat such as solar energy. In comparison with absorption system, an adsorption system has no problems such as corrosion at high temperature and salt crystallization. In comparison with vapor compression refrigeration system, it has the advantages of simple control, no moving parts and less noise. This paper introduces the basic theory of adsorption cycle as well as the advanced adsorption cycles such as heat and mass recovery cycle, thermal wave cycle and convection thermal wave cycle. The types, characteristics, advantages and drawbacks of different adsorbents used in adsorption refrigeration systems are also summarized. This article will increase the awareness of this emerging cooling technology among the HVAC engineers and help them select appropriate adsorption systems in energy-efficient building design.

  6. Regulation and tissue-specific distribution of mRNAs for three extracellular invertase isoenzymes of tomato suggests an important function in establishing and maintaining sink metabolism.

    PubMed Central

    Godt, D E; Roitsch, T

    1997-01-01

    The aim of the present study was to gain insight into the contribution of extracellular invertases for sink metabolism in tomato (Lycopersicon esculentum L.). The present study shows that extracellular invertase isoenzymes are encoded by a gene family comprising four members: Lin5, Lin6, Lin7, and Lin8. The regulation of mRNA levels by internal and external signals and the distribution in sink and source tissues has been determined and compared with mRNA levels of the intracellular sucrose (Suc)-cleaving enzymes Suc synthase and vacuolar invertase. The specific regulation of Lin5, Lin6, and Lin7 suggests an important function of apoplastic cleavage of Suc by cell wall-bound invertase in establishing and maintaining sink metabolism. Lin6 is expressed under conditions that require a high carbohydrate supply. The corresponding mRNA shows a sink tissue-specific distribution and the concentration is elevated by stress-related stimuli, by the growth-promoting phytohormone zeatin, and in response to the induction of heterotrophic metabolism. The expression of Lin5 and Lin7 in gynoecia and stamens, respectively, suggests an important function in supplying carbohydrates to these flower organs, whereas the Lin7 mRNA was found to be present exclusively in this specific sink organ. PMID:9306701

  7. Distribution of metabolic fluxes towards glycerol phosphate and L-lactate from fructose 1,6-biphosphate in vitro: effect of glycerol phosphate dehydrogenase.

    PubMed

    Riol-Cimas, J M; Meléndez-Hevia, E

    1986-01-01

    A metabolic system in vitro, which converts fructose 1,6-biphosphate into the two alternative products, lactate and glycerol phosphate, was designed to study the distribution of metabolic fluxes and, specifically, the control of glycerol phosphate production rate in rat muscle extract. Experiments were carried out at several protein concentrations by dilution of rat muscle extract, showing non-linear behaviours of flux versus protein concentration. These were hyperbolic for glycerol phosphate and logarithmic for L-lactate. The influence of the flux towards any alternate product on the rate giving the other was studied by stimulation of each. Results obtained show that in this system, flux towards glycerol phosphate is not affected by lactate production and the same occurs for the contrary case. Glycerol phosphate dehydrogenase seems to be the only enzyme in this system whose activity controls the flux towards glycerol phosphate. PMID:3758466

  8. ABSORPTION, DISTRIBUTION, EXCRETION, AND METABOLISM OF A SINGLE ORAL DOSE OF O-ETHYL O-4-NITROPHENYL PHENYLPHOSPHONOTHIOATE IN HENS

    EPA Science Inventory

    The disposition and metabolism of a single oral 10 mg/kg (LD50) of uniformly phenyl-labeled (14C)EPN (O-ethyl O-4 nitrophenyl (14C) phenylphosphonothioate) were studied in adult hens. The birds were protected from acute toxicity with atropine sulfate. Three treated hens were kill...

  9. Establishing population distribution of drug-metabolizing enzyme activities for the use of salivary caffeine as a dynamic liver function marker in a Singaporean Chinese population.

    PubMed

    Chia, Hazel Yiting; Yau, Wai-Ping; Ho, Han Kiat

    2016-04-01

    The salivary paraxanthine/caffeine molar ratio has been proposed as a novel dynamic liver function test to guide dose adjustments of drugs hepatically cleared by CYP1A2. Its usability requires an established population norm as well as the factors influencing the ratio and actual concentrations. To address this knowledge gap, salivary caffeine and paraxanthine concentrations were measured at 4 h post caffeine dose in healthy Chinese individuals who had undergone 24 h of caffeine abstinence. The metabolic ratio was calculated and statistical analysis was performed. From the 52 participants (26 males; 30 regular caffeine consumers) recruited, the salivary paraxanthine/caffeine molar ratio was normally distributed with a mean and SD of 0.5 ± 0.2. No statistically significant factors (BMI, body weight, gender and regularity of caffeine intake) affecting the metabolic ratio were found. The caffeine concentration and total caffeine plus paraxanthine concentrations were lower in males than in females, and lower in regular caffeine consumers than in non-regular caffeine consumers. The 4 h salivary metabolic ratio (mean: 0.5) was generally not significantly different from the literature reported salivary, serum and plasma ratios measured at 4-9 h in healthy individuals (mean range 0.4-0.7) but was significantly higher than the literature reported 6 h plasma ratio and salivary ratios measured at 1-6 h in patients with liver disease or mild abnormal liver function tests (mean range 0.03-0.2). Overall, the population norm of the salivary metabolic ratio in a Singaporean Chinese population established in this study is distinct from individuals with liver disease or mild abnormal liver function tests and provides the benchmark for dosage adjustments of drugs metabolized by CYP1A2. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26862045

  10. 2-Methoxyethanol metabolism, embryonic distribution, and macromolecular adduct formation in the rat: the effect of radiofrequency radiation-induced hyperthermia.

    PubMed

    Cheever, K L; Swearengin, T F; Edwards, R M; Nelson, B K; Werren, D W; Conover, D L; DeBord, D G

    2001-05-31

    Exposure of pregnant rats to the solvent 2-methoxyethanol (2ME) and radiofrequency (RF) radiation results in greater than additive fetal malformations (Nelson, B.K., Conover, D.L., Brightwell, W.S., Shaw, P.B., Werren, D.W., Edwards, R.M., Lary, J.M., 1991. Marked increase in the teratogenicity of the combined administration of the industrial solvent 2-methoxyethanol and radiofrequency radiation in rats. Teratology 43, 621-34; Nelson, B.K., Conover, D.L., Shaw, P.B., Werren, D.W., Edwards, R.M., Hoberman, A.M., 1994. Interactive developmental toxicity of radiofrequency radiation and 2-methoxyethanol in rats. Teratology 50, 275-93). The current study evaluated the metabolism of 14C-labeled 2ME and the distribution of methoxyacetic acid (MAA) in maternal and embryonic tissues of pregnant Sprague-Dawley rats either exposed to 10 MHz RF radiation or sham conditions. Additionally, adduct formation for both plasma and embryonic protein was tested as a possible biomarker for the observed 2ME/RF teratogenicity. Rats were administered [ethanol-1,2-(14)C]-2ME (150 mg/kg, 161 microCi/rat average) by gavage on gestation day 13 immediately before RF radiation sufficient to elevate body temperature to 42 degrees C for 30 min. Concurrent sham- and RF-exposed rats were sacrificed at 3, 6, 24 or 48 h for harvest of maternal blood, urine, embryos and extra-embryonic fluid. Tissues were either digested for determination of radioactivity or deproteinized with TCA and analyzed by HPLC for quantification of 2ME metabolites. Results show the presence of 2ME and seven metabolites, with the major metabolite, MAA, peaking at 6 h in the tissues tested. MAA, the proximal teratogen, was detectable in maternal serum, urine, embryo and extraembryonic fluid 48 h after dosing. Clearance of total body 14C was significantly reduced for the RF-exposed animals (P<0.05) for the 24-48 h period, but MAA values for serum, embryos and extraembryonic fluid were similar for both sham- and RF-exposed rats

  11. Competitive adsorption of heavy metals onto sesame straw biochar in aqueous solutions.

    PubMed

    Park, Jong-Hwan; Ok, Yong Sik; Kim, Seong-Heon; Cho, Ju-Sik; Heo, Jong-Soo; Delaune, Ronald D; Seo, Dong-Cheol

    2016-01-01

    Objective of this research was to evaluate adsorption of heavy metals in mono and multimetal forms onto sesame straw biochar (SSB). Competitive sorption of metals by SSB has never been reported previously. The maximum adsorption capacities (mgg(-1)) of metals by SSB were in the order of Pb (102)≫Cd (86)≫Cr (65)>Cu (55)≫Zn (34) in the monometal adsorption isotherm and Pb (88)≫Cu (40)≫Cr (21)>Zn (7)⩾Cd (5) in the multimetal adsorption isotherm. Based on data obtained from the distribution coefficients, Freundlich and Langmuir adsorption models, and three-dimensional simulation, multimetal adsorption behaviors differed from monometal adsorption due to competition. Especially, during multimetal adsorption, Cd was easily exchanged and substituted by other metals. Further competitive adsorption studies are necessary in order to accurately estimate the heavy metal adsorption capacity of biochar in natural environments. PMID:26082184

  12. ARSENIC TREATMENT BY ADSORPTIVE TECHNOLOGY

    EPA Science Inventory

    Presentation will discuss the removal of arsenic from drinking water using the adsorptive media treatment process. Fundamental information is provided on the design and operation of adsorptive media technology including the selection of the adsorptive media. The information cites...

  13. A Simple Adsorption Experiment

    ERIC Educational Resources Information Center

    Guirado, Gonzalo; Ayllon, Jose A.

    2011-01-01

    The study of adsorption phenomenon is one of the most relevant and traditional physical chemistry experiments performed by chemistry undergraduate students in laboratory courses. In this article, we describe an easy, inexpensive, and straightforward way to experimentally determine adsorption isotherms using pieces of filter paper as the adsorbent…

  14. Metabolic model of Synechococcus sp. PCC 7002: Prediction of flux distribution and network modification for enhanced biofuel production.

    PubMed

    Hendry, John I; Prasannan, Charulata B; Joshi, Aditi; Dasgupta, Santanu; Wangikar, Pramod P

    2016-08-01

    Flux Balance Analysis was performed with the Genome Scale Metabolic Model of a fast growing cyanobacterium Synechococcus sp. PCC 7002 to gain insights that would help in engineering the organism as a production host. Gene essentiality and synthetic lethality analysis revealed a reduced metabolic robustness under genetic perturbation compared to the heterotrophic bacteria Escherichia coli. Under glycerol heterotrophy the reducing equivalents were generated from tricarboxylic acid cycle rather than the oxidative pentose phosphate pathway. During mixotrophic growth in glycerol the photosynthetic electron transport chain was predominantly used for ATP synthesis with a photosystem I/photosystem II flux ratio higher than that observed under autotrophy. An exhaustive analysis of all possible double reaction knock outs was performed to reroute fixed carbon towards ethanol and butanol production. It was predicted that only ∼10% of fixed carbon could be diverted for ethanol and butanol production. PMID:27036328

  15. 40 CFR 796.2750 - Sediment and soil adsorption isotherm.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... to sediments and soils is an important process that affects a chemical's distribution in the.... “Adsorption, desorption of parathion as affected by soil organic matter,” Journal of Agricultural and Food... 40 Protection of Environment 32 2014-07-01 2014-07-01 false Sediment and soil adsorption...

  16. 40 CFR 796.2750 - Sediment and soil adsorption isotherm.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... to sediments and soils is an important process that affects a chemical's distribution in the.... “Adsorption, desorption of parathion as affected by soil organic matter,” Journal of Agricultural and Food... 40 Protection of Environment 33 2012-07-01 2012-07-01 false Sediment and soil adsorption...

  17. 40 CFR 796.2750 - Sediment and soil adsorption isotherm.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... to sediments and soils is an important process that affects a chemical's distribution in the.... “Adsorption, desorption of parathion as affected by soil organic matter,” Journal of Agricultural and Food... 40 Protection of Environment 32 2011-07-01 2011-07-01 false Sediment and soil adsorption...

  18. Adsorption of ferrous ions onto montmorillonites

    NASA Astrophysics Data System (ADS)

    Qin, Dawei; Niu, Xia; Qiao, Min; Liu, Gang; Li, Hongxin; Meng, Zhenxiao

    2015-04-01

    The adsorption of Fe (II) onto montmorillonites was investigated through initial concentration, contact time, pH and temperature. During the whole adsorption process, the ascorbic acid (Vitamin C) was added as a kind of antioxidant, at the same time, deionized water (after boiling) and nitrogen protection were also used to avoid oxidation. The Fe2+/Fetotal ratio of the iron exists in the Fe-montmorillonites was found more than 95%. Two kinetic models, including pseudo-first-order and pseudo-second-order model, were used to analyze the adsorption process of Fe (II) on montmorillonites. The results of our study showed that adsorption process fitted with pseudo-second-order well. Adsorption isotherms showed that Langmuir model was better than Freundlich model. The thermodynamic parameters ΔG0 and ΔH0 were 3.696 kJ/mol and 6.689 kJ/mol (we just gave the values at 298 K), respectively. The positive values at different temperatures showed that the adsorption process was non-spontaneous and endothermic. The characteristics of materials were determined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Surface area and porosity analyzer, Thermogravimetric analysis (TGA), Differential scanning calorimeter (DSC) and Zeta potential distribution.

  19. Tissue distribution, excretion, and the metabolic pathway of 2,2',4,4',5-penta-chlorinated diphenylsulfide (CDPS-99) in ICR mice.

    PubMed

    Zeng, Xiaolan; Zhang, Xuesheng; Qin, Li; Wang, Zunyao

    2015-09-15

    The tissue distribution, excretion, and metabolic pathway of 2,2',4,4',5-penta-chlorinated diphenylsulfide (CDPS-99) in ICR mice were investigated after oral perfusion at 10mg/kg body weight (b.w.). Biological samples were extracted and separated and, for the first time, were determined by a novel, sensitive, and specific GC-MS method under the full scan and selected ion monitoring (SIM) modes. The results showed that the concentrations of CDPS-99 in the liver, kidneys, and serum reached a maximum after a one-day exposure and that the CDPS-99 concentration in the liver was the highest (3.43μg/g). The increase in the concentration of CDPS-99 in muscle, skin, and adipose tissue was slower, and the concentrations of CDPS-99 achieved their highest levels after 3 days of exposure. It was observed that the CDPS-99 concentration in adipose tissue was still very high (0.71μg/g) after 21 days of exposure, which suggested that CDPS-99 was able to accumulate in adipose tissue. In addition, mouse feces accounted for approximately 75% of the total gavage dose, indicating that CDPS-99 was mainly excreted via mouse feces. Metabolism analysis demonstrated that there were three possible metabolic pathways of CDPS-99 in mice: dechlorination reactions with the formation of tetra-CDPS and hydroxylation and oxidation reactions with the formation of OH-CDPS-99 and chlorinated diphenylsulfone. The present study will help to develop a better understanding of mammalian metabolism of CDPS-99. PMID:26262600

  20. Expression and distribution of genes encoding for polyamine-metabolizing enzymes in the different zones of male and female mouse kidneys.

    PubMed

    Levillain, Olivier; Ramos-Molina, Bruno; Forcheron, Fabien; Peñafiel, Rafael

    2012-11-01

    The role of polyamines in renal physiology is only partially understood. Moreover, most of the data on the enzymes of polyamine metabolism come from studies using whole kidneys. The aim of the present study was to analyze the mRNA abundance of the genes implicated in both the polyamine biosynthetic and catabolic pathways in different renal zones of male and female mice, by means of the quantitative reverse transcription-polymerase chain reaction. Our results indicate that there is an uneven distribution of the different mRNAs studied in the five renal zones: superficial cortex, deep cortex, outer stripe of the outer medulla (OS), inner stripe of the outer medulla (IS), and the inner medulla + papilla (IM). The biosynthetic genes, ornithine decarboxylase (ODC) and spermine synthase, were more expressed in the cortex, whereas the mRNAs of the catabolic genes spermine oxidase (SMO) and diamine oxidase were more abundant in IS and IM. The genes involved in the regulation of polyamine synthesis (AZ1, AZ2 and AZIN1) were expressed in all the renal zones, predominantly in the cortex, while AZIN2 gene was more abundant in the OS. ODC, SMO, spermidine synthase and spermidine/spermine acetyl transferase expression was higher in males than in females. In conclusion, the genes encoding for the polyamine metabolism were specifically and quantitatively distributed along the corticopapillary axis of male and female mouse kidneys, suggesting that their physiological role is essential in defined renal zones and/or nephron segments. PMID:22562773

  1. Revealing Differences in Metabolic Flux Distributions between a Mutant Strain and Its Parent Strain Gluconacetobacter xylinus CGMCC 2955

    PubMed Central

    Liu, Miao; Yang, Xiao-Ning; Zhu, Hui-Xia; Jia, Yuan-Yuan; Jia, Shi-Ru; Piergiovanni, Luciano

    2014-01-01

    A better understanding of metabolic fluxes is important for manipulating microbial metabolism toward desired end products, or away from undesirable by-products. A mutant strain, Gluconacetobacter xylinus AX2-16, was obtained by combined chemical mutation of the parent strain (G. xylinus CGMCC 2955) using DEC (diethyl sulfate) and LiCl. The highest bacterial cellulose production for this mutant was obtained at about 11.75 g/L, which was an increase of 62% compared with that by the parent strain. In contrast, gluconic acid (the main byproduct) concentration was only 5.71 g/L for mutant strain, which was 55.7% lower than that of parent strain. Metabolic flux analysis indicated that 40.1% of the carbon source was transformed to bacterial cellulose in mutant strain, compared with 24.2% for parent strain. Only 32.7% and 4.0% of the carbon source were converted into gluconic acid and acetic acid in mutant strain, compared with 58.5% and 9.5% of that in parent strain. In addition, a higher flux of tricarboxylic acid (TCA) cycle was obtained in mutant strain (57.0%) compared with parent strain (17.0%). It was also indicated from the flux analysis that more ATP was produced in mutant strain from pentose phosphate pathway (PPP) and TCA cycle. The enzymatic activity of succinate dehydrogenase (SDH), which is one of the key enzymes in TCA cycle, was 1.65-fold higher in mutant strain than that in parent strain at the end of culture. It was further validated by the measurement of ATPase that 3.53–6.41 fold higher enzymatic activity was obtained from mutant strain compared with parent strain. PMID:24901455

  2. VISUALIZATION OF TISSUE DISTRIBUTION AND METABOLISM OF BENZO[A]PYRENE IN EARLY EMBRYONIC MEDAKA (ORYZIAS LATIPES)

    EPA Science Inventory

    Fish early life stages are highly sensitive to exposure to persistent bioaccumulative toxicants (PBTs). The factors that contribute to this are unknown, but may include the distribution of PBTs to sensitive tissues during critical stages of development. Multiphoton laser scannin...

  3. Hybrid adsorptive membrane reactor

    DOEpatents

    Tsotsis, Theodore T.; Sahimi, Muhammad; Fayyaz-Najafi, Babak; Harale, Aadesh; Park, Byoung-Gi; Liu, Paul K. T.

    2011-03-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  4. Hybrid adsorptive membrane reactor

    NASA Technical Reports Server (NTRS)

    Tsotsis, Theodore T. (Inventor); Sahimi, Muhammad (Inventor); Fayyaz-Najafi, Babak (Inventor); Harale, Aadesh (Inventor); Park, Byoung-Gi (Inventor); Liu, Paul K. T. (Inventor)

    2011-01-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  5. Efficient adsorption of phenanthrene by simply synthesized hydrophobic MCM-41 molecular sieves

    NASA Astrophysics Data System (ADS)

    Hu, Yun; He, Yinyun; Wang, Xiaowen; Wei, Chaohai

    2014-08-01

    Hydrophobic molecular sieve MCM-41 including surfactant template was synthesized by a simple method. The adsorption properties of this material toward phenanthrene were studied. The effects of adsorbent dose and pH value on the adsorption process as well as the adsorption mechanism and reuse performance were investigated. The template-containing MCM-41 showed a significant adsorption for phenanthrene, due to its hydrophobicity created by the surfactant template in MCM-41. The solution pH had little effect on the adsorption capacity. The adsorption kinetic could be fitted well with pseudo-second-order kinetic model. The adsorption equilibrium was fitted well by the linear model, and the adsorption process followed the liquid/solid phase distribution mechanism. The thermodynamic results indicated that the adsorption was a spontaneous and exothermic process.

  6. Adsorption of herbicides using activated carbons

    SciTech Connect

    Derbyshire, F.; Jagtoyan, M.; Lafferty, C.; Kimber, G.

    1996-10-01

    This work describes development of a series of novel activated carbon materials and their testing for possible water treatment applications by studying the adsorption of sodium pentachlorphenolate, PCP (a common herbicide/wood preservative). Although the application of activated carbons is an established technology for the treatment of public water supplies, there is a growing need for materials with higher selectivity and adsorptive capacities as well as high abrasion resistance. The materials that will be discussed include extruded wood-derived carbons with novel pore size distributions and high hardness, as well as activated carbon fiber composites. Comparisons will be made with commercial granular water treatment carbons.

  7. Adsorption of polyampholytes on charged surfaces.

    PubMed

    Ozon, F; di Meglio, J-M; Joanny, J-F

    2002-06-01

    We have studied the adsorption of neutral polyampholytes on model charged surfaces that have been characterized by contact angle and streaming current measurements. The loop size distributions of adsorbed polymer chains have been obtained using atomic-force microscopy (AFM) and compared to recent theoretical predictions. We find a qualitative agreement with theory; the higher the surface charge, the smaller the number of monomers in the adsorbed layer. We propose an original scenario for the adsorption of polyampholytes on surfaces covered with both neutral long-chain and charged short-chain thiols. PMID:15010954

  8. CHARACTERIZATION OF AMINOPEPTIDASE IN THE FREE-LIVING NEMATODE PANAGRELLUS REDIVIVUS: SUBCELLULAR DISTRIBUTION AND POSSIBLE ROLE IN NEUROPEPTIDE METABOLISM

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aminopeptidase was detected in homogenates of the free-living nematode Panagrellus redivivus with the aminoacyl substrate L-alanine-4-nitroanilide (Ala-4-NA). Subcellular distribution of the enzyme was unequal, with approximately 80 percent of total aminopeptidase in the soluble fraction and the rem...

  9. Database Extraction of Metabolite Information of Drug Candidates: Analysis of 27 AstraZeneca Compounds with Human Absorption, Distribution, Metabolism, and Excretion Data.

    PubMed

    Iegre, Jessica; Hayes, Martin A; Thompson, Richard A; Weidolf, Lars; Isin, Emre M

    2016-05-01

    As part of the drug discovery and development process, it is important to understand the human metabolism of a candidate drug prior to clinical studies. Preclinical in vitro and in vivo experiments across species are conducted to build knowledge concerning human circulating metabolites in preparation for clinical studies; therefore, the quality of these experiments is critical. Within AstraZeneca, all metabolite identification (Met-ID) information is stored in a global database using ACDLabs software. In this study, the Met-ID information derived from in vitro and in vivo studies for 27 AstraZeneca drug candidates that underwent human absorption, distribution, metabolism, and excretion studies was extracted from the database. The retrospective analysis showed that 81% of human circulating metabolites were previously observed in preclinical in vitro and/or in vivo experiments. A detailed analysis was carried out to understand which human circulating metabolites were not captured in the preclinical experiments. Metabolites observed in human hepatocytes and rat plasma but not seen in circulation in humans (extraneous metabolites) were also investigated. The majority of human specific circulating metabolites derive from multistep biotransformation reactions that may not be observed in in vitro studies within the limited time frame in which cryopreserved hepatocytes are active. Factors leading to the formation of extraneous metabolites in preclinical studies seemed to be related to species differences with respect to transporter activity, secondary metabolism, and enzyme kinetics. This retrospective analysis assesses the predictive value of Met-ID experiments and improves our ability to discriminate between metabolites expected to circulate in humans and irrelevant metabolites seen in preclinical studies. PMID:26868617

  10. Distribution and metabolism of dimethylsulfoniopropionate (DMSP) and phylogenetic affiliation of DMSP-assimilating bacteria in northern Baffin Bay/Lancaster Sound

    NASA Astrophysics Data System (ADS)

    Motard-CôTé, J.; Levasseur, M.; Scarratt, M. G.; Michaud, S.; Gratton, Y.; Rivkin, R. B.; Keats, K.; Gosselin, M.; Tremblay, J.-É.; Kiene, R. P.; Lovejoy, C.

    2012-02-01

    We determined the distribution and bacterial metabolism of dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) in the two dominant surface water masses in northern Baffin Bay/Lancaster Sound during September 2008. Concentrations of particulate DMSP (DMSPp; 5-70 nmol L-1) and the DMSPp:Chl a ratios (15-229 nmol μg-1) were relatively high, suggesting the presence of DMSP-rich phytoplankton taxa. Photosynthetic picoeukaryotes and total prokaryotes were tenfold and threefold more abundant in Baffin Bay surface water (BBS) than in Arctic surface water (AS), respectively. Heterotrophic bacterial production (0.07-2.5 μC L-1 d-1) and bacterial turnover rate constants for dissolved DMSP (DMSPd) were low (0.03-0.11 h-1) compared with the values previously reported in warmer and more productive environments. Nonetheless, a relatively large proportion (12%-31%) of the DMSP metabolized by the bacteria was converted into DMS. Additionally, between 40% and 65% of the total bacterial cells incorporated sulfur from DMSPd, with Gammaproteobacteria and non-Roseobacter Alphaproteobacteria (AlfR-) contributing proportionally more to total DMSP-incorporating cells. The contribution of AlfR- to the total prokaryotic community was 50% higher in BBS than in AS, while the bacterial rate constants for DMSPd turnover were 78% higher in BBS than in AS. These results show that the two different Arctic water masses host specific microbial assemblages that result in distinct affinity for DMSP.

  11. Adsorption on Highly Ordered Porous Alumina

    NASA Astrophysics Data System (ADS)

    Mistura, Giampaolo; Bruschi, Lorenzo; Lee, Woo

    2016-04-01

    Porous anodic aluminum oxide (AAO) is characterized by a regular arrangement of the pores with a narrow pore size distribution over extended areas, uniform pore depth, and solid pore walls without micropores. Thanks to significant improvements in anodization techniques, structural engineering of AAO allows to accurately tailor the pore morphology. These features make porous AAO an excellent substrate to study adsorption phenomena. In this paper, we review recent experiments involving the adsorption in porous AAO. Particular attention will be devoted to adsorption in straight and structured pores with a closed end which shed new light on fundamental issues like the origin of hysteresis in closed end pores and the nature of evaporation from ink-bottle pores. The results will be compared to those obtained in other synthetic materials like porous silicon and silica.

  12. Distribution and metabolism of dihomo-gamma-linolenic acid (DGLA, 20:3n-6) by oral supplementation in rats.

    PubMed

    Umeda-Sawada, Rumi; Fujiwara, Yoko; Ushiyama, Ikuko; Sagawa, Satoe; Morimitsu, Yasujiro; Kawashima, Hiroshi; Ono, Yoshiko; Kiso, Yoshinobu; Matsumoto, Akiyo; Seyama, Yousuke

    2006-09-01

    We compared the dietary effects of dihomo-gamma-linolenic acid (DGLA) contained in the DGLA oil produced by a fungus with gamma-linolenic acid (GLA) on the fatty acid composition. Wistar rats were fed with three kinds of oil for two weeks as follows: (i) control group: corn oil; (ii) GLA group: borage oil; (iii) DGLA group: DGLA oil/safflower oil = 55:45. The DGLA concentrations in the liver, serum, and brain of the DGLA group were higher than those of the GLA oil group. We also examined the dose effect of DGLA. The DGLA levels in the liver, serum, and brain significantly increased with increasing dosage of DGLA in the diet. DGLA administration significantly increased the ratio of PGE1/PGE2 in the rat plasma. The mechanism for GLA administration to improve atopic eczema is thought to involve an increase in the concentration of DGLA metabolized from GLA, so these results suggest that the dietary effect of DGLA would be more dominant than GLA. PMID:16960355

  13. Tissue distribution and metabolism of the putative cancer chemopreventive agent 3',4',5'-trimethoxyflavonol (TMFol) in mice.

    PubMed

    Saad, Shaban E A; Jones, Donald J L; Norris, Leonie M; Horner-Glister, Emma; Patel, Ketan R; Britton, Robert G; Steward, William P; Gescher, Andreas J; Brown, Karen; Sale, Stewart

    2012-12-01

    3',4',5'-Trimethoxyflavonol (TMFol) is a synthetic flavonol with preclinical cancer chemopreventive properties. The hypothesis was tested that, in mice, p.o. administration of TMFol results in measureable levels of the parent in target tissues. A single oral dose (240 mg/kg) was administered to mice (n = 4 per time point) with time points ranging from 5 to 1440 min. TMFol and its metabolites were identified and quantitated in all tissues by high-performance liquid chromatography (HPLC). Plasma levels of TMFol were at the limit of quantification or below, although metabolites were identified. Peak levels of TMFol in the gastrointestinal tract and the prostate averaged 1671 ± 265 µg/g (5.3 µmol/g) and 6.0 ± 1.6 µg/g (18.4 nmol/g), and occurred 20 and 360 min post-dose, respectively. The area under the tissue concentration-time curve (AUC) for TMFol was greater than those of the metabolites, indicating that TMFol is relatively metabolically stable. Micromolar TMFol levels are easily achieved in the prostate and gastrointestinal tract, suggesting that TMFol might exert chemopreventive efficacy at these tissue sites. Further investigations are warranted to elucidate the potential chemopreventive potency of TMFol. PMID:22454297

  14. Adsorption coefficients for TNT on soil and clay minerals

    NASA Astrophysics Data System (ADS)

    Rivera, Rosángela; Pabón, Julissa; Pérez, Omarie; Muñoz, Miguel A.; Mina, Nairmen

    2007-04-01

    To understand the fate and transport mechanisms of TNT from buried landmines is it essential to determine the adsorption process of TNT on soil and clay minerals. In this research, soil samples from horizons Ap and A from Jobos Series at Isabela, Puerto Rico were studied. The clay fractions were separated from the other soil components by centrifugation. Using the hydrometer method the particle size distribution for the soil horizons was obtained. Physical and chemical characterization studies such as cation exchange capacity (CEC), surface area, percent of organic matter and pH were performed for the soil and clay samples. A complete mineralogical characterization of clay fractions using X-ray diffraction analysis reveals the presence of kaolinite, goethite, hematite, gibbsite and quartz. In order to obtain adsorption coefficients (K d values) for the TNT-soil and TNT-clay interactions high performance liquid chromatography (HPLC) was used. The adsorption process for TNT-soil was described by the Langmuir model. A higher adsorption was observed in the Ap horizon. The Freundlich model described the adsorption process for TNT-clay interactions. The affinity and relative adsorption capacity of the clay for TNT were higher in the A horizon. These results suggest that adsorption by soil organic matter predominates over adsorption on clay minerals when significant soil organic matter content is present. It was found that, properties like cation exchange capacity and surface area are important factors in the adsorption of clayey soils.

  15. Characterization of micro- and mesoporous materials using accelerated dynamics adsorption.

    PubMed

    Qajar, Ali; Peer, Maryam; Rajagopalan, Ramakrishnan; Foley, Henry C

    2013-10-01

    Porosimetry is a fundamental characterization technique used in development of new porous materials for catalysis, membrane separation, and adsorptive gas storage. Conventional methods like nitrogen and argon adsorption at cryogenic temperatures suffer from slow adsorption dynamics especially for microporous materials. In addition, CO2, the other common probe, is only useful for micropore characterization unless being compressed to exceedingly high pressures to cover all required adsorption pressures. Here, we investigated the effect of adsorption temperature, pressure, and type of probe molecule on the adsorption dynamics. Methyl chloride (MeCl) was used as the probe molecule, and measurements were conducted near room temperature under nonisothermal condition and subatmospheric pressure. A pressure control algorithm was proposed to accelerate adsorption dynamics by manipulating the chemical potential of the gas. Collected adsorption data are transformed into pore size distribution profiles using the Horvath-Kavazoe (HK), Saito-Foley (SF), and modified Kelvin methods revised for MeCl. Our study shows that the proposed algorithm significantly speeds up the rate of data collection without compromising the accuracy of the measurements. On average, the adsorption rates on carbonaceous and aluminosilicate samples were accelerated by at least a factor of 4-5. PMID:23919893

  16. Effect of grain size on uranium(VI) surface complexation kinetics and adsorption additivity.

    PubMed

    Shang, Jianying; Liu, Chongxuan; Wang, Zheming; Zachara, John M

    2011-07-15

    The contribution of variable grain sizes to uranium adsorption/desorption was studied using a sediment from the US DOE Hanford site. The sediment was wet sieved into four size fractions: coarse sand (1-2 mm), medium sand (0.2-1 mm), fine sand (0.053-0.2 mm), and clay/silt fraction (<0.053 mm). For each size fraction and their composite (sediment), batch and flow-cell experiments were performed to determine uranium adsorption isotherms and kinetic uranium adsorption and subsequent desorption. The results showed that uranium adsorption isotherms and adsorption/desorption kinetics were size specific, reflecting the effects of size-specific adsorption site concentration and kinetic rate constants. The larger-size fraction had a larger mass percentage in the sediment but with a smaller adsorption site concentration and generally a slower uranium adsorption/desorption rate. The same equilibrium surface complexation reaction and reaction constant could describe uranium adsorption isotherms for all size fractions and the composite after accounting for the effect of adsorption site concentration. Mass-weighted, linear additivity was observed for both uranium adsorption isotherms and adsorption/desorption kinetics in the composite. One important implication of this study is that grain-size distribution may be used to estimate uranium adsorption site and adsorption/desorption kinetic rates in heterogeneous sediments from a common location. PMID:21648458

  17. Adsorption of nicotine from aqueous solution onto hydrophobic zeolite type USY

    NASA Astrophysics Data System (ADS)

    Lazarevic, Natasa; Adnadjevic, Borivoj; Jovanovic, Jelena

    2011-07-01

    The isothermal adsorption of nicotine from an aqueous solution onto zeolite type USY was investigated. The adsorption isotherms of nicotine onto the zeolite at different temperatures ranging from 298 to 322 K were determined. It was found that the adsorption isotherms can be described by the model of Freundlich adsorption isotherm. Based on the adsorption isotherms the changes of adsorption heat, free energy and entropy with adsorption degree were determined. The determined decrease of adsorption heat with adsorption degree can be explained by the presence of the adsorption centers of different energy and concentration on interface of zeolite-nicotine solution. It was found that the probability function of density distribution of the heat of adsorption (DDF) has exponential form. It was concluded that the possibility of fitting the adsorption isotherms of nicotine onto the zeolite by Freundlich adsorption isotherm was a direct consequence of that. The determined increase in entropy with the increase in adsorption degree can be explained with the change of phase state of adsorbed nicotine.

  18. Adsorption of gases on carbon molecular sieves

    SciTech Connect

    Vyas, S.N.; Patwardhan, S.R.; Vijayalakshmi, S. . Dept. of Chemical Engineering); Ganesh, K.S. )

    1994-12-01

    Adsorption on carbon molecular sieves (CMS) prepared by coke deposition has become an interesting area of adsorption due to its microporous nature and favorable separation factor on size and shape selectivity basis for many gaseous systems. In the present work CMS was synthesized from coconut shell through three major steps, namely, carbonization, activation, and coke deposition by hydrocarbon cracking. The crushed, washed, and sieved granules of coconut shell (particle size 2--3 mm) were pretreated with sodium silicate solution and oven-dried at 150 C to create the inorganic sites necessary for coke deposition. Carbonization and activation of the dried granules were carried out at 800 C, for 30 min each. The activated char thus produced was subjected to hydrocarbon cracking at 600 C for periods varying from 30 to 180 min. The product samples were characterized in terms of adsorption isotherm, kinetic adsorption curve, surface area, pore volume, pore size distribution, and characteristic energy for adsorption by using O[sub 2], N[sub 2], C[sub 2]H[sub 2], CO[sub 2], C[sub 3]H[sub 6], and CH[sub 4].

  19. Adsorption in sparse networks. 1: Cylinder model

    SciTech Connect

    Scherer, G.W.

    1998-06-15

    Materials with very low density, such as aerogels, are networks with polymers or chains of particles joined at nodes, where the spacing of the nodes is large compared to the thickness of the chains. In such a material, most of the solid surface has positive curvature, so condensation of an adsorbate is more difficult than condensation in a body containing cavities whose surfaces have negative curvature. A model is presented in which the network is represented by straight cylinders joined at nodes with coordination numbers 4, 6, or 12. The shape of the adsorbate/adsorptive interface is obtained for each network by minimizing its surface area. The adsorption behavior is found to depend on the ratio of the node separation, l, to the radius of the cylinders, a: if l/a exceeds a critical value (which depends on the coordination of the node), then the curvature of the adsorbate/adsorptive interface approaches zero while the adsorbate occupies a small fraction of the pore volume; if l/a is less than the critical value, then condensation occurs. Even in the latter case, interpretation of the adsorption isotherm in terms of cylindrical pores (as in the BJH model) yields apparent pore sizes much greater than the actual spacing of the nodes. In a companion paper, this model is applied to silica aerogels and found to give a good fit to both the adsorption and desorption curves with a single distribution of node spacings.

  20. Visceral adiposity and its anatomical distribution as predictors of the metabolic syndrome and cardiometabolic risk factor levels

    PubMed Central

    Demerath, Ellen W; Reed, Derek; Rogers, Nikki; Sun, Shumei S; Lee, Miryoung; Choh, Audrey C; Couch, William; Czerwinski, Stefan A; Chumlea, W Cameron; Siervogel, Roger M; Towne, Bradford

    2009-01-01

    Background Despite the recognition that central obesity plays a critical role in chronic disease, few large-scale imaging studies have documented human variation in abdominal adipose tissue patterning. Objective We aimed to compare the associations between abdominal subcutaneous adipose tissue (ASAT) and visceral abdominal tissue (VAT), which were measured at different locations across the abdomen, and the presence of the metabolic syndrome (MS; National Cholesterol Education Program Adult Treatment Panel III definition) and individual cardiometabolic risk factors. Design This study included 713 non-Hispanic whites aged 18–86 y, in whom VAT and ASAT were assessed by using multiple-image magnetic resonance imaging. The anatomical position of the magnetic resonance image containing the maximum VAT area for each subject was used as a measure of VAT patterning. Multivariate linear and logistic regression analyses were used to examine the relation of VAT, ASAT, and VAT patterning to cardiometabolic risk. Results VAT mass was a stronger predictor of the MS than was ASAT mass, but ASAT mass (and other measures of subcutaneous adiposity) had signification interactions with VAT mass, whereby elevated ASAT reduced the probability of MS among men with high VAT (P = 0.0008). There was variation across image locations in the association of VAT area with the MS in men, and magnetic resonance images located 4–8 cm above L4–L5 provided the strongest correlations between VAT area and cardiometabolic risk factors. Subjects whose maximum VAT area was higher in the abdomen had higher LDL-cholesterol concentrations (R2 = 0.07, P = 0.0001), independent of age and adiposity. Conclusion Further studies are needed to confirm the effects of VAT patterning on cardiometabolic risk. PMID:18996861

  1. Potential of collagen-like triple helical peptides as drug carriers: Their in vivo distribution, metabolism, and excretion profiles in rodents.

    PubMed

    Yasui, Hiroyuki; Yamazaki, Chisato M; Nose, Hiroshi; Awada, Chihiro; Takao, Toshifumi; Koide, Takaki

    2013-11-01

    Collagen-model peptides composed of (X-Y-Gly)n sequences were used to study the triple helical structure of collagen. We report the stability of these collagen-like peptides in biological fluids, and their pharmacokinetics including distribution, metabolism, and excretion in animals. A typical collagen-model peptide, H-(Pro-Hyp-Gly)10-OH, was found to be extremely stable in the plasma and distributed mainly in the vascular blood space, and was eliminated through glomerular filtration in the kidneys. Triple helical peptides of (X-Y-Gly)n sequences were quantitatively recovered from the urine of rats after intravenous injection regardless of the differences in peptide net charge between -3 and +6 per triple helix. In contrast, the renal clearance became less efficient when the number of triplet repeats (n) was 12 or more. We also demonstrated the application of a collagen-like triple helical peptide as a novel drug carrier in the blood with a high urinary excretion profile. We further demonstrated that a collagen-like triple helical peptide conjugated to a spin probe, PROXYL, has the potential to evaluate the redox status of oxidative stress-induced animals in vivo. PMID:23494659

  2. Adsorption of humic acids and trace metals in natural waters

    NASA Technical Reports Server (NTRS)

    Leung, W. H.

    1982-01-01

    Studies concerning the interactions between suspended hydrous iron oxide and dissolved humic acids and trace metals are reported. As a major component of dissolved organic matters and its readiness for adsorption at the solid/water interface, humic acids may play a very important role in the organometallic geochemistry of suspended sediments and in determining the fate and distribution of trace metals, pesticides and anions in natural water systems. Most of the solid phases in natural waters contain oxides and hydroxides. The most simple promising theory to describe the interactions of hydrous iron oxide interface is the surface complex formation model. In this model, the adsorptions of humic acids on hydrous iron oxide may be interpreted as complex formation of the organic bases (humic acid oxyanions) with surface Fe ions. Measurements on adsorptions were made in both fresh water and seawater. Attempts have been made to fit our data to Langmuir adsorption isotherm. Adsorption equilibrium constants were determined.

  3. Consequences of phosphoenolpyruvate:sugar phosphotranferase system and pyruvate kinase isozymes inactivation in central carbon metabolism flux distribution in Escherichia coli

    PubMed Central

    2012-01-01

    Background In Escherichia coli phosphoenolpyruvate (PEP) is a key central metabolism intermediate that participates in glucose transport, as precursor in several biosynthetic pathways and it is involved in allosteric regulation of glycolytic enzymes. In this work we generated W3110 derivative strains that lack the main PEP consumers PEP:sugar phosphotransferase system (PTS-) and pyruvate kinase isozymes PykA and PykF (PTS-pykA- and PTS-pykF-). To characterize the effects of these modifications on cell physiology, carbon flux distribution and aromatics production capacity were determined. Results When compared to reference strain W3110, strain VH33 (PTS-) displayed lower specific rates for growth, glucose consumption and acetate production as well as a higher biomass yield from glucose. These phenotypic effects were even more pronounced by the additional inactivation of PykA or PykF. Carbon flux analysis revealed that PTS inactivation causes a redirection of metabolic flux towards biomass formation. A cycle involving PEP carboxylase (Ppc) and PEP carboxykinase (Pck) was detected in all strains. In strains W3110, VH33 (PTS-) and VH35 (PTS-, pykF-), the net flux in this cycle was inversely correlated with the specific rate of glucose consumption and inactivation of Pck in these strains caused a reduction in growth rate. In the PTS- background, inactivation of PykA caused a reduction in Ppc and Pck cycling as well as a reduction in flux to TCA, whereas inactivation of PykF caused an increase in anaplerotic flux from PEP to OAA and an increased flux to TCA. The wild-type and mutant strains were modified to overproduce L-phenylalanine. In resting cells experiments, compared to reference strain, a 10, 4 and 7-fold higher aromatics yields from glucose were observed as consequence of PTS, PTS PykA and PTS PykF inactivation. Conclusions Metabolic flux analysis performed on strains lacking the main activities generating pyruvate from PEP revealed the high degree of

  4. New Adsorption Methods.

    ERIC Educational Resources Information Center

    Wankat, Phillip C.

    1984-01-01

    Discusses a simple method for following the movement of a solute in an adsorption or ion exchange system. This movement is used to study a variety of operational methods, including continuous flow and pulsed flow counter-current operations and simulated counter-current systems. Effect of changing thermodynamic variables is also considered. (JM)

  5. Distribution and metabolism of ingested NO3- and NO2- in germfree and conventional-flora rats.

    PubMed Central

    Witter, J P; Balish, E

    1979-01-01

    Germfree and conventional-flora Sprague-Dawley rats were fed sodium nitrate or sodium nitrite in their drinking water (1,000 microgram/ml), and various organs, tissues, and sections of the intestinal tract were assayed for nitrate (NO3-) and nitrite (NO2-) by a spectrophotometric method. When fed NO3-, germfree rats had chemically detectable levels of NO3- (only) in the stomach, small intestine, cecum, and colon. Conventional-flora rats fed NO3- had both NO3- and NO2- in the stomach, but only NO3- in the small intestine and colon. When fed NO2-, germfree rats had both NO3- and NO2- in the entire gastrointestinal tract. Conventional-flora rats fed NO2- had both ions in the stomach and small intestine, but only NO3- in the large intestine. Conventional-flora rats fed NO3- or NO2- had lower amounts of these ions in the gastrointestinal tract than comparably fed germfree rats. Control (non-NO3- or NO2--fed) germfree and conventional-flora rats had trace amounts of NO3- (only) in their stomachs and bladders. These results, in conjunction with various in vitro studies with intestinal contents, suggest that NO3- or NO2- reduction is a function of the normal bacterial flora, whereas NO2- oxidation is attributable to the mammalian host. In addition, the distribution of these ions after their ingestion appears more widespread in the body than previously thought. PMID:543701

  6. Molecular Characterization of the Diversity and Distribution of a Thermal Spring Microbial Community by Using rRNA and Metabolic Genes▿ †

    PubMed Central

    Hall, Justine R.; Mitchell, Kendra R.; Jackson-Weaver, Olan; Kooser, Ara S.; Cron, Brandi R.; Crossey, Laura J.; Takacs-Vesbach, Cristina D.

    2008-01-01

    The diversity and distribution of a bacterial community from Coffee Pots Hot Spring, a thermal spring in Yellowstone National Park with a temperature range of 39.3 to 74.1°C and pH range of 5.75 to 6.91, were investigated by sequencing cloned PCR products and quantitative PCR (qPCR) of 16S rRNA and metabolic genes. The spring was inhabited by three Aquificae genera—Thermocrinis, Hydrogenobaculum, and Sulfurihydrogenibium—and members of the Alpha-, Beta-, and Gammaproteobacteria, Firmicutes, Acidobacteria, Deinococcus-Thermus, and candidate division OP5. The in situ chemical affinities were calculated for 41 potential metabolic reactions using measured environmental parameters and a range of hydrogen and oxygen concentrations. Reactions that use oxygen, ferric iron, sulfur, and nitrate as electron acceptors were predicted to be the most energetically favorable, while reactions using sulfate were expected to be less favorable. Samples were screened for genes used in ammonia oxidation (amoA, bacterial gene only), the reductive tricarboxylic acid (rTCA) cycle (aclB), the Calvin cycle (cbbM), sulfate reduction (dsrAB), nitrogen fixation (nifH), nitrite reduction (nirK), and sulfide oxidation (soxEF1) by PCR. Genes for carbon fixation by the rTCA cycle and nitrogen fixation were detected. All aclB sequences were phylogenetically related and spatially correlated to Sulfurihydrogenibium 16S rRNA gene sequences using qPCR (R2 = 0.99). This result supports the recent finding of citrate cleavage by enzymes other than ATP citrate lyase in the rTCA cycle of the Aquificaceae family. We briefly consider potential biochemical mechanisms that may allow Sulfurihydrogenibium and Thermocrinis to codominate some hydrothermal environments. PMID:18539788

  7. Long-Term Impacts of Foetal Malnutrition Followed by Early Postnatal Obesity on Fat Distribution Pattern and Metabolic Adaptability in Adult Sheep

    PubMed Central

    Khanal, Prabhat; Johnsen, Lærke; Axel, Anne Marie Dixen; Hansen, Pernille Willert; Kongsted, Anna Hauntoft; Lyckegaard, Nette Brinch; Nielsen, Mette Olaf

    2016-01-01

    We aimed to investigate whether over- versus undernutrition in late foetal life combined with obesity development in early postnatal life have differential implications for fat distribution and metabolic adaptability in adulthood. Twin-pregnant ewes were fed NORM (100% of daily energy and protein requirements), LOW (50% of NORM) or HIGH (150%/110% of energy/protein requirements) diets during the last trimester. Postnatally, twin-lambs received obesogenic (HCHF) or moderate (CONV) diets until 6 months of age, and a moderate (obesity correcting) diet thereafter. At 2½ years of age (adulthood), plasma metabolite profiles during fasting, glucose, insulin and propionate (in fed and fasted states) tolerance tests were examined. Organ weights were determined at autopsy. Early obesity development was associated with lack of expansion of perirenal, but not other adipose tissues from adolescence to adulthood, resulting in 10% unit increased proportion of mesenteric of intra-abdominal fat. Prenatal undernutrition had a similar but much less pronounced effect. Across tolerance tests, LOW-HCHF sheep had highest plasma levels of cholesterol, urea-nitrogen, creatinine, and lactate. Sex specific differences were observed, particularly with respect to fat deposition, but direction of responses to early nutrition impacts were similar. However, prenatal undernutrition induced greater metabolic alterations in adult females than males. Foetal undernutrition, but not overnutrition, predisposed for adult hypercholesterolaemia, hyperureaemia, hypercreatinaemia and hyperlactataemia, which became manifested only in combination with early obesity development. Perirenal expandability may play a special role in this context. Differential nutrition recommendations may be advisable for individuals with low versus high birth weights. PMID:27257993

  8. Long-Term Impacts of Foetal Malnutrition Followed by Early Postnatal Obesity on Fat Distribution Pattern and Metabolic Adaptability in Adult Sheep.

    PubMed

    Khanal, Prabhat; Johnsen, Lærke; Axel, Anne Marie Dixen; Hansen, Pernille Willert; Kongsted, Anna Hauntoft; Lyckegaard, Nette Brinch; Nielsen, Mette Olaf

    2016-01-01

    We aimed to investigate whether over- versus undernutrition in late foetal life combined with obesity development in early postnatal life have differential implications for fat distribution and metabolic adaptability in adulthood. Twin-pregnant ewes were fed NORM (100% of daily energy and protein requirements), LOW (50% of NORM) or HIGH (150%/110% of energy/protein requirements) diets during the last trimester. Postnatally, twin-lambs received obesogenic (HCHF) or moderate (CONV) diets until 6 months of age, and a moderate (obesity correcting) diet thereafter. At 2½ years of age (adulthood), plasma metabolite profiles during fasting, glucose, insulin and propionate (in fed and fasted states) tolerance tests were examined. Organ weights were determined at autopsy. Early obesity development was associated with lack of expansion of perirenal, but not other adipose tissues from adolescence to adulthood, resulting in 10% unit increased proportion of mesenteric of intra-abdominal fat. Prenatal undernutrition had a similar but much less pronounced effect. Across tolerance tests, LOW-HCHF sheep had highest plasma levels of cholesterol, urea-nitrogen, creatinine, and lactate. Sex specific differences were observed, particularly with respect to fat deposition, but direction of responses to early nutrition impacts were similar. However, prenatal undernutrition induced greater metabolic alterations in adult females than males. Foetal undernutrition, but not overnutrition, predisposed for adult hypercholesterolaemia, hyperureaemia, hypercreatinaemia and hyperlactataemia, which became manifested only in combination with early obesity development. Perirenal expandability may play a special role in this context. Differential nutrition recommendations may be advisable for individuals with low versus high birth weights. PMID:27257993

  9. Molecular characterization of the diversity and distribution of a thermal spring microbial community by using rRNA and metabolic genes.

    PubMed

    Hall, Justine R; Mitchell, Kendra R; Jackson-Weaver, Olan; Kooser, Ara S; Cron, Brandi R; Crossey, Laura J; Takacs-Vesbach, Cristina D

    2008-08-01

    The diversity and distribution of a bacterial community from Coffee Pots Hot Spring, a thermal spring in Yellowstone National Park with a temperature range of 39.3 to 74.1 degrees C and pH range of 5.75 to 6.91, were investigated by sequencing cloned PCR products and quantitative PCR (qPCR) of 16S rRNA and metabolic genes. The spring was inhabited by three Aquificae genera--Thermocrinis, Hydrogenobaculum, and Sulfurihydrogenibium--and members of the Alpha-, Beta-, and Gammaproteobacteria, Firmicutes, Acidobacteria, Deinococcus-Thermus, and candidate division OP5. The in situ chemical affinities were calculated for 41 potential metabolic reactions using measured environmental parameters and a range of hydrogen and oxygen concentrations. Reactions that use oxygen, ferric iron, sulfur, and nitrate as electron acceptors were predicted to be the most energetically favorable, while reactions using sulfate were expected to be less favorable. Samples were screened for genes used in ammonia oxidation (amoA, bacterial gene only), the reductive tricarboxylic acid (rTCA) cycle (aclB), the Calvin cycle (cbbM), sulfate reduction (dsrAB), nitrogen fixation (nifH), nitrite reduction (nirK), and sulfide oxidation (soxEF1) by PCR. Genes for carbon fixation by the rTCA cycle and nitrogen fixation were detected. All aclB sequences were phylogenetically related and spatially correlated to Sulfurihydrogenibium 16S rRNA gene sequences using qPCR (R(2) = 0.99). This result supports the recent finding of citrate cleavage by enzymes other than ATP citrate lyase in the rTCA cycle of the Aquificaceae family. We briefly consider potential biochemical mechanisms that may allow Sulfurihydrogenibium and Thermocrinis to codominate some hydrothermal environments. PMID:18539788

  10. Influence of dietary fat on metabolism of (14-/sup 14/C)erucic acid in the perfused rat liver. Distribution of metabolites in lipid classes

    SciTech Connect

    Holmer, G.; Ronneberg, R.

    1986-06-01

    Two groups of rats were fed diets containing 20% by weight of either partially hydrogenated marine oil supplemented with sunflower seed oil (PHMO) or palm oil (PO) for 8 wk. Using a liver perfusion system, the effect of dietary long chain monoenoic fatty acids on the uptake and metabolism of (14-/sup 14/C)erucic acid was studied. The perfusion times were 15 and 60 min, respectively. The two groups showed equal ability for erucic acid uptake in the liver but differed in the channeling of the fatty acids into various metabolic pathways. A higher metabolic turnover of 22:1 in the PHMO livers relative to the PO livers was demonstrated by an increased recovery of total (/sup 14/C)labeling in the triglyceride (TG) and phospholipid (PL) fractions, already evident after 15 min of perfusion. The chain-shortening capacity was highest in the PHMO group, reflected by a higher (/sup 14/C)18:1 incorporation in both TG and PL, and increasing from 15 to 60 min of perfusion. The amount of (/sup 14/C)18:1 found in PL and TG after 60 min of perfusion of livers from rats fed PO corresponded to that shown for the PHMO group after 15 min. The PL demonstrated a discrimination against 22:1 compared to TG, and, when available, 18:1 was highly preferred for PL-synthesis. The total fatty acid distribution in the TG, as determined by gas liquid chromatography (GLC), reflected the composition of the dietary fats. In the total liver PL, 22:1 and 20:1 were present in negligible amounts, although the PHMO diet contained 12-13% of both 22:1 and 20:1. In the free fatty acid fraction (FFA), the major part of the radioactivity (approximately 80%) was (14-/sup 14/C)erucic acid, and only small amounts of (/sup 14/C)18:1 (less than 2%) were present, even after 60 min of perfusion. The shortened-chain 18:1 was readily removed from the FFA pool and preferentially used for lipid esterification.

  11. Sustained metabolic scope.

    PubMed Central

    Peterson, C C; Nagy, K A; Diamond, J

    1990-01-01

    Sustained metabolic rates (SusMR) are time-averaged metabolic rates that are measured in free-ranging animals maintaining constant body mass over periods long enough that metabolism is fueled by food intake rather than by transient depletion of energy reserves. Many authors have suggested that SusMR of various wild animal species are only a few times resting (basal or standard) metabolic rates (RMR). We test this conclusion by analyzing all 37 species (humans, 31 other endothermic vertebrates, and 5 ectothermic vertebrates) for which SusMR and RMR had both been measured. For all species, the ratio of SusMR to RMR, which we term sustained metabolic scope, is less than 7; most values fall between 1.5 and 5. Some of these values, such as those for Tour de France cyclists and breeding birds, are surely close to sustainable metabolic ceilings for the species studied. That is, metabolic rates higher than 7 times RMR apparently cannot be sustained indefinitely. These observations pose several questions: whether the proximate physiological causes of metabolic ceilings reside in the digestive tract's ability to process food or in each tissue's metabolic capacity; whether ceiling values are independent of the mode of energy expenditure; whether ceilings are set by single limiting physiological capacities or by coadjusted clusters of capacities (symmorphosis); what the ultimate evolutionary causes of metabolic ceilings are; and how metabolic ceilings may limit animals' reproductive effort, foraging behavior, and geographic distribution. PMID:2315323

  12. Maternal transfer, distribution, and metabolism of BDE-47 and its related hydroxylated, methoxylated analogs in zebrafish (Danio rerio).

    PubMed

    Wen, Quan; Liu, Hong-ling; Zhu, Yu-ting; Zheng, Xin-mei; Su, Guan-yong; Zhang, Xiao-wei; Yu, Hong-xia; Giesy, John P; Lam, Michael H W

    2015-02-01

    OH-PBDEs have been reported to be more potent than the postulated precursor PBDEs or corresponding MeO-PBDEs. However, there are contradictory reports for transformation of these compounds in organisms, particularly, for biotransformation of OH-PBDEs and MeO-PBDEs, only one study reported transformation of 6-OH-BDE-47 and 6-MeO-BDE-47 in Japanese medaka. In present study zebrafish (Danio rerio) were exposed to BDE-47, 6-OH-BDE-47, 6-MeO-BDE-47, 2'-OH-BDE-28 and 2'-MeO-BDE-28 in the diet for 20 d. Concentrations of each exposed compound were measured in eggs collected on days 0, 5, 10, 15 or 20. After 20 d exposure, concentrations of precursor and biotransformation products in liver and liver-free residual carcass were measured by use of GC-MS/MS. Total mass of the five compounds in bodies of adults were: 2'-MeO-BDE-28 ∼ 6-MeO-BDE-47>BDE-47>2'-OH-BDE-28>6-OH-BDE-47. MeO-PBDEs were also accumulated more into parental fish body than in liver, while OH-PBDEs accumulated in liver more than in liver-free residual carcass. Concentrations in liver of males were greater than those of females. This result suggests sex-related differences in accumulation. Ratios between concentration in eggs and liver (E/L) were: 2.9, 1.7, 0.8, 0.4 and 0.1 for 6-MeO-BDE-47, BDE-47, 6-OH-BDE-47, 2'-MeO-BDE-28 and 2'-OH-BDE-28, respectively. This result suggests transfer from adult females to eggs. BDE-47 was not transformed into OH-PBDEs or MeO-PBDEs. Inter-conversions of 6-OH-BDE-47 and 6-MeO-BDE-47, 2'-OH-BDE-28 and 2'-MeO-BDE-28 were observed, with metabolite/precursor concentration ratios for 6-OH-BDE-47, 6-MeO-BDE-47, 2'-OH-BDE-28 and 2'-MeO-BDE-28 being 3.8%, 14.6%, 2.9% and 76.0%, respectively. Congener-specific differences were observed in distributions between liver and carcass, maternal transfer and transformation. The two MeO-PBDEs were accumulated into adults, transferred to eggs, and were transformed to the structural similar OH-PBDEs, which might be more toxic. BDE-47 was

  13. Scaling metabolic rate fluctuations.

    PubMed

    Labra, Fabio A; Marquet, Pablo A; Bozinovic, Francisco

    2007-06-26

    Complex ecological and economic systems show fluctuations in macroscopic quantities such as exchange rates, size of companies or populations that follow non-Gaussian tent-shaped probability distributions of growth rates with power-law decay, which suggests that fluctuations in complex systems may be governed by universal mechanisms, independent of particular details and idiosyncrasies. We propose here that metabolic rate within individual organisms may be considered as an example of an emergent property of a complex system and test the hypothesis that the probability distribution of fluctuations in the metabolic rate of individuals has a "universal" form regardless of body size or taxonomic affiliation. We examined data from 71 individuals belonging to 25 vertebrate species (birds, mammals, and lizards). We report three main results. First, for all these individuals and species, the distribution of metabolic rate fluctuations follows a tent-shaped distribution with power-law decay. Second, the standard deviation of metabolic rate fluctuations decays as a power-law function of both average metabolic rate and body mass, with exponents -0.352 and -1/4 respectively. Finally, we find that the distributions of metabolic rate fluctuations for different organisms can all be rescaled to a single parent distribution, supporting the existence of general principles underlying the structure and functioning of individual organisms. PMID:17578913

  14. Fundamentals of high pressure adsorption

    SciTech Connect

    Zhou, Y.P.; Zhou, L.

    2009-12-15

    High-pressure adsorption attracts research interests following the world's attention to alternative fuels, and it exerts essential effect on the study of hydrogen/methane storage and the development of novel materials addressing to the storage. However, theoretical puzzles in high-pressure adsorption hindered the progress of application studies. Therefore, the present paper addresses the major theoretical problems that challenged researchers: i.e., how to model the isotherms with maximum observed in high-pressure adsorption; what is the adsorption mechanism at high pressures; how do we determine the quantity of absolute adsorption based on experimental data. Ideology and methods to tackle these problems are elucidated, which lead to new insights into the nature of high-pressure adsorption and progress in application studies, for example, in modeling multicomponent adsorption, hydrogen storage, natural gas storage, and coalbed methane enrichment, was achieved.

  15. Body fat distribution and cortisol metabolism in healthy men: enhanced 5beta-reductase and lower cortisol/cortisone metabolite ratios in men with fatty liver.

    PubMed

    Westerbacka, Jukka; Yki-Järvinen, Hannele; Vehkavaara, Satu; Häkkinen, Anna-Maija; Andrew, Ruth; Wake, Deborah J; Seckl, Jonathan R; Walker, Brian R

    2003-10-01

    In Cushing's syndrome, cortisol causes fat accumulation in specific sites most likely to be associated with insulin resistance, notably in omental adipose and also perhaps in the liver. In idiopathic obesity, cortisol-metabolizing enzymes may play a key role in determining body fat distribution. Increased regeneration of cortisol from cortisone within adipose by 11beta-hydroxysteroid dehydrogenase (HSD) type 1 (11HSD1) has been proposed to cause visceral fat accumulation, whereas decreased hepatic 11HSD1 may protect the liver from glucocorticoid excess. Increased inactivation of cortisol by 5alpha- and 5beta-reductases in the liver may drive compensatory activation of the hypothalamic-pituitary-adrenal axis, hence increasing adrenal androgens and 'android' central obesity. This study aimed to examine relationships between these enzymes and detailed measurements of body fat distribution. Twenty-five healthy men (age, 22-57 yr; body mass index, 20.6-35.6 kg/m(2)) were recruited from occupational health services. Body composition was assessed by anthropometric measurements, bioimpedance, and cross-sectional abdominal magnetic resonance imaging scans. Liver fat content was assessed by magnetic resonance imaging spectroscopy. Insulin sensitivity was measured in a euglycemic hyperinsulinemic clamp. Cortisol metabolites were measured in a 24-h urine sample by gas chromatography-mass spectrometry. In vivo hepatic 11HSD1 activity was measured by generation of plasma cortisol after an oral dose of cortisone. In vitro 11HSD1 activity and mRNA were measured in 18 subjects who consented to provide abdominal sc adipose biopsies. Indices of obesity (body mass index, whole-body percentage fat, waist/hip ratio) were associated with higher urinary excretion of 5alpha- and 5beta-reduced cortisol metabolites (for percentage fat, P < 0.05 and P < 0.01, respectively) and increased adipose 11HSD1 activity (P < 0.05). Liver fat accumulation was associated with a selective increase in

  16. Metabolic neuropathies

    MedlinePlus

    Neuropathy - metabolic ... can be caused by many different things. Metabolic neuropathy may be caused by: A problem with the ... one of the most common causes of metabolic neuropathies. People who are at the highest risk for ...

  17. Thaumarchaeotal Signature Gene Distribution in Sediments of the Northern South China Sea: an Indicator of the Metabolic Intersection of the Marine Carbon, Nitrogen, and Phosphorus Cycles?

    PubMed Central

    Zhou, Haixia; Yang, Jinying; Ge, Huangmin; Jiao, Nianzhi; Luan, Xiwu; Klotz, Martin G.

    2013-01-01

    Thaumarchaeota are abundant and active in marine waters, where they contribute to aerobic ammonia oxidation and light-independent carbon fixation. The ecological function of thaumarchaeota in marine sediments, however, has rarely been investigated, even though marine sediments constitute the majority of the Earth's surface. Thaumarchaeota in the upper layer of sediments may contribute significantly to the reservoir of nitrogen oxides in ocean waters and thus to productivity, including the assimilation of carbon. We tested this hypothesis in the northern South China Sea (nSCS), a section of a large oligotrophic marginal sea with limited influx of nutrients, including nitrogen, by investigating the diversity, abundance, community structure, and spatial distribution of thaumarchaeotal signatures in surface sediments. Quantitative real-time PCR using primers designed to detect 16S rRNA and amoA genes in sediment community DNA revealed a significantly higher abundance of pertinent thaumarchaeotal than betaproteobacterial genes. This finding correlates with high levels of hcd genes, a signature of thaumarchaeotal autotrophic carbon fixation. Thaumarchaeol, a signature lipid biomarker for thaumarchaeota, constituted the majority of archaeal lipids in marine sediments. Sediment temperature and organic P and silt contents were identified as key environmental factors shaping the community structure and distribution of the monitored thaumarchaeotal amoA genes. When the pore water PO43− concentration was controlled for via partial-correlation analysis, thaumarchaeotal amoA gene abundance significantly correlated with the sediment pore water NO2− concentration, suggesting that the amoA-bearing thaumarchaeota contribute to nitrite production. Statistical analyses also suggest that thaumarchaeotal metabolism could serve as a pivotal intersection of the carbon, nitrogen, and phosphorus cycles in marine sediments. PMID:23335759

  18. Extracorporeal adsorption of endotoxin.

    PubMed

    Staubach, K H; Rosenfeldt, J A; Veit, O; Bruch, H P

    1997-02-01

    In a porcine endotoxin shock model using a continuous intravenous endotoxin infusion of 250 ng/kg body weight per hour, the cardiorespiratory and hematologic parameters were studied while applying a new on-line polymyxin B immobilized adsorption system. This preliminary report shows that the new adsorbent can remove endotoxin selectively from the circulation and confers a good amount of protection from endotoxin-induced cardiopulmonary decompensation as well as hematologic alterations. Survival time could be extended from 216 min to 313 min. Whereas cardiac output and mean arterial pressure declined critically after 3 h in the controls, the treated group remained stable for another 3 h. These data show that endotoxin adsorption by polymyxin B coupled covalently to acrylic spheres as an adjunctive on-line measure in the septic syndrome seems feasible. PMID:10225785

  19. Experiment K-7-21: Effect of Microgravity on 1: Metabolic Enzymes of Type 1 and Type 2 Muscle Fibers, and on 2: Metabolic Enzymes, Neurotransmitter Amino Acids, and Neurotransmitter Associated Enzymes in Selected Regions of the Central Nervous System. Part 2; The Distribution of Selected Enzymes and Amino Acids in the Hippocampal Formation

    NASA Technical Reports Server (NTRS)

    Lowry, O. H.; Krasnov, I.; Ilyina-Kakueva, E. I.; Nemeth, P. M.; McDougal, D. B., Jr.; Choksi, R.; Carter, J. G.; Chi, M. M. Y.; Manchester, J. K.; Pusateri, M. E.

    1994-01-01

    Six key metabolic enzymes plus glutaminase and glutamate decarboxylase, as well as glutamate, aspartate and GABA, were measured in 11 regions of the hippocampal formation of synchronous, flight and tail suspension rats. Major differences were observed in the normal distribution patterns of each enzyme and amino acid, but no substantive effects of either microgravity or tail suspension on these patterns were clearly demonstrated.

  20. Distribution, metabolism and toxicity of inhaled sulfur dioxide and endogenously generated sulfite in the respiratory tract of normal and sulfite oxidase-deficient rats

    SciTech Connect

    Gunnison, A.F.; Sellakumar, A.; Currie, D.; Snyder, E.A.

    1987-01-01

    We report on the distribution, metabolism, and toxicity of sulfite in the respiratory tract and other tissues of rats exposed to endogenously generated sulfite or to inhaled sulfur dioxide (SO/sub 2/). Graded sulfite oxidase deficiency was induced in several groups of rats by manipulating their tungsten to molybdenum intake ratio. Endogenously generated sulfite and S-sulfonate compounds (a class of sulfite metabolite) accumulated in the respiratory tract tissues and in the plasma of these rats in inverse proportion to hepatic sulfite oxidase activity. In contrast to this systemic mode of exposure, sulfite exposure of normal, sulfite oxidase-competent rats via inhaled SO/sub 2/ (10 and 30 ppm) was restricted to the airways. Minor pathological changes consisting of epithelial hyperplasia, mucoid degeneration, and desquamation of epithelium were observed only in the tracheas and bronchi of the rats inhaling SO/sub 2/, even though the concentration of sulfite plus S-sulfonates in the tracheas and bronchi of these rats was considerably lower than that in the endogenously exposed rats. We attribute this histological damage to hydrogen ions stemming from inhaled SO/sub 2/, not to the sulfite/bisulfite ions that are also a product of inhaled SO/sub 2/. In addition to the lungs and trachea, all other tissues examined, except the testes, appeared to be refractory to high concentrations of endogenously generated sulfite. The testes of grossly sulfite oxidase-deficient rats were severely atrophied and devoid of spermatogenic cells.

  1. Regenerable adsorption system

    NASA Technical Reports Server (NTRS)

    Roychoudhury, Subir (Inventor); Perry, Jay (Inventor); Walsh, Dennis (Inventor)

    2006-01-01

    A method for regenerable adsorption includes providing a substrate that defines at least one layer of ultra short channel length mesh capable of conducting an electrical current therethrough, coating at least a portion of the substrate with a desired sorbent for trace contaminant control or CO.sub.2 sorption, resistively heating the substrate, and passing a flowstream through the substrate and in contact with the sorbent.

  2. Effect of Grain Size on Uranium(VI) Surface Complexation Kinetics and Adsorption Additivity

    SciTech Connect

    Shang, Jianying; Liu, Chongxuan; Wang, Zheming; Zachara, John M.

    2011-07-27

    Laboratory experiments were performed to investigate the contribution of variable grain sizes to uranium adsorption/desorption in a sediment collected from the US DOE Hanford site. The sediment was wet-sieved into four size fractions: coarse sand (1-2 mm), medium sand (0.2-1 mm), fine sand (0.05-0.2 mm), and clay/silt fraction (< 0.05mm). For each size fraction and their composite (sediment), batch experiments were performed to determine uranium adsorption isotherms, and stirred flow-cell experiments were conducted to derive kinetic data of uranium adsorption and subsequent desorption. The results showed that uranium adsorption isotherms and adsorption/desorption kinetics were size-specific, reflecting the effects of size-specific adsorption site concentration and kinetic rate constants. The larger-size fraction had a larger mass percentage in the sediment, but with a smaller adsorption site concentration and generally a slower uranium adsorption/desorption rate. The same equilibrium surface complexation reaction and reaction constant could describe uranium adsorption isotherms for all size fractions and the composite after accounting for the effect of adsorption site concentration. Mass-weighted, linear additivity was observed for both uranium adsorption isotherms and adsorption/desorption kinetics in the composite. Our analysis also showed that uranium adsorption site concentration estimated from the adsorption isotherms was 3 orders of magnitude less than a site concentration estimated from sediment surface area and generic site density. One important implication of this study is that grain size distribution may be used to estimate uranium adsorption site, and adsorption/desorption kinetic rates in heterogeneous sediments from a common location.

  3. New Insights in Tissue Distribution, Metabolism, and Excretion of [3H]-Labeled Antibody Maytansinoid Conjugates in Female Tumor-Bearing Nude Rats.

    PubMed

    Walles, Markus; Rudolph, Bettina; Wolf, Thierry; Bourgailh, Julien; Suetterlin, Martina; Moenius, Thomas; Peraus, Gisela; Heudi, Olivier; Elbast, Walid; Lanshoeft, Christian; Bilic, Sanela

    2016-07-01

    For antibody drug conjugates (ADCs), the fate of the cytotoxic payload in vivo needs to be well understood to mitigate toxicity risks and properly design the first in-patient studies. Therefore, a distribution, metabolism, and excretion (DME) study with a radiolabeled rat cross-reactive ADC ([(3)H]DM1-LNL897) targeting the P-cadherin receptor was conducted in female tumor-bearing nude rats. Although multiple components [total radioactivity, conjugated ADC, total ADC, emtansine (DM1) payload, and catabolites] needed to be monitored with different technologies (liquid scintillation counting, liquid chromatography/mass spectrometry, enzyme-linked immunosorbent assay, and size exclusion chromatography), the pharmacokinetic data were nearly superimposable with the various techniques. [(3)H]DM1-LNL897 was cleared with half-lives of 51-62 hours and LNL897-related radioactivity showed a minor extent of tissue distribution. The highest tissue concentrations of [(3)H]DM1-LNL897-related radioactivity were measured in tumor. Complimentary liquid extraction surface analysis coupled to micro-liquid chromatography-tandem mass spectrometry data proved that the lysine (LYS)-4(maleimidylmethyl) cyclohexane-1-carboxylate-DM1 (LYS-MCC-DM1) catabolite was the only detectable component distributed evenly in the tumor and liver tissue. The mass balance was complete with up to 13.8% ± 0.482% of the administered radioactivity remaining in carcass 168 hours postdose. LNL897-derived radioactivity was mainly excreted via feces (84.5% ± 3.12%) and through urine only to a minor extent (4.15% ± 0.462%). In serum, the major part of radioactivity could be attributed to ADC, while small molecule disposition products were the predominant species in excreta. We show that there is a difference in metabolite profiles depending on which derivatization methods for DM1 were applied. Besides previously published results on LYS-MCC-DM1 and MCC-DM1, maysine and a cysteine conjugate of DM1 could be

  4. Synthesis of Ordered Mesoporous Silica for Energy-efficient Adsorption Systems

    NASA Astrophysics Data System (ADS)

    Endo, Akira; Komori, Kou; Inagi, Yuki; Fujisaki, Satoko; Yamamoto, Takuji

    Energy-efficient adsorption systems, such as adsorption heat pump, desiccant cooling, humidity control system, and so on, are expected as a energy exchange process because they are able to utilize low temperature exhaust heat. As an adsorbent for such systems, materials with large adsorption capacity in the pressure range of practical operation are preferable. To enable the design and synthesis of materials with large heat storage capacity, the pore structure of adsorbents should be optimized for each systems. In this paper, we synthesized ordered mesoporous silica (MPS) with an arrow pore size distribution of around 2nm by a solvent evaporation method and evaluated their water adsorption properties. The adsorption isotherms for MPSs showed steep increase at a relative humidity corresponding to their pore size. Since MPSs have a large adsorption capacity than conventional materials in the relative humidity region of practical operation, they are expected for new adsorbents for energy-efficient adsorption systems.

  5. Adsorption and isothermal models of atrazine by zeolite prepared from Egyptian kaolin

    NASA Astrophysics Data System (ADS)

    Jamil, Tarek S.; Gad-Allah, Tarek A.; Ibrahim, Hanan S.; Saleh, Tamer S.

    2011-01-01

    The adsorption behavior of Atrazine on zeolites, prepared from Egyptian kaolin, has been studied in order to consider the application of these types of zeolites in water purification. The batch mode has been employed, using atrazine solution of concentration ranging from 2 to 10 mg /l. The adsorption capacity and distribution coefficients ( Kd) were determined for the adsorption system as a function of sorbate concentration. It was found that, under the studies concentrations, the percent of adsorbed atrazine on both zeolites match to Langmuir and Freundlich adsorption models. The constants of each model were calculated to assess the adsorption behavior of atrazine on each type of zeolite. According to the equilibrium studies, adsorption of atrazine on zeolite X at lower concentrations is much better than that on zeolite A. The application of Dublin-Kaganer-Radushkevich model revealed physisorption endothermic adsorption process for both zeolites. These results show that natural zeolites hold great potential to remove hazardous materials such as atrazine from water.

  6. Sub-ambient carbon dioxide adsorption properties of nitrogen doped graphene

    SciTech Connect

    Tamilarasan, P.; Ramaprabhu, Sundara

    2015-04-14

    Carbon dioxide adsorption on carbon surface can be enhanced by doping the surface with heterogeneous atoms, which can increase local surface affinity. This study presents the carbon dioxide adsorption properties of nitrogen doped graphene at low pressures (<100 kPa). Graphene was exposed to nitrogen plasma, which dopes nitrogen atoms into carbon hexagonal lattice, mainly in pyridinic and pyrrolic forms. It is found that nitrogen doping significantly improves the CO{sub 2} adsorption capacity at all temperatures, due to the enrichment of local Lewis basic sites. In general, isotherm and thermodynamic parameters suggest that doped nitrogen sites have nearly same adsorption energy of surface defects and residual functional groups. The isosteric heat of adsorption remains in physisorption range, which falls with surface coverage, suggesting the distribution of magnitude of adsorption energy. The absolute values of isosteric heat and entropy of adsorption are slightly increased upon nitrogen doping.

  7. Adsorption-driven translocation of polymer chain into nanopores

    NASA Astrophysics Data System (ADS)

    Yang, Shuang; Neimark, Alexander V.

    2012-06-01

    The polymer translocation into nanopores is generally facilitated by external driving forces, such as electric or hydrodynamic fields, to compensate for entropic restrictions imposed by the confinement. We investigate the dynamics of translocation driven by polymer adsorption to the confining walls that is relevant to chromatographic separation of macromolecules. By using the self-consistent field theory, we study the passage of a chain trough a small opening from cis to trans compartments of spherical shape with adsorption potential applied in the trans compartment. The chain transfer is modeled as the Fokker-Plank diffusion along the free energy landscape of the translocation pass represented as a sum of the free energies of cis and trans parts of the chain tethered to the pore opening. We investigate how the chain length, the size of trans compartment, the magnitude of adsorption potential, and the extent of excluded volume interactions affect the translocation time and its distribution. Interplay of these factors brings about a variety of different translocation regimes. We show that excluded volume interactions within a certain range of adsorption potentials can cause a local minimum on the free energy landscape, which is absent for ideal chains. The adsorption potential always leads to the decrease of the free energy barrier, increasing the probability of successful translocation. However, the translocation time depends non-monotonically of the magnitude of adsorption potential. Our calculations predict the existence of the critical magnitude of adsorption potential, which separates favorable and unfavorable regimes of translocation.

  8. Adsorption-driven translocation of polymer chain into nanopores.

    PubMed

    Yang, Shuang; Neimark, Alexander V

    2012-06-01

    The polymer translocation into nanopores is generally facilitated by external driving forces, such as electric or hydrodynamic fields, to compensate for entropic restrictions imposed by the confinement. We investigate the dynamics of translocation driven by polymer adsorption to the confining walls that is relevant to chromatographic separation of macromolecules. By using the self-consistent field theory, we study the passage of a chain trough a small opening from cis to trans compartments of spherical shape with adsorption potential applied in the trans compartment. The chain transfer is modeled as the Fokker-Plank diffusion along the free energy landscape of the translocation pass represented as a sum of the free energies of cis and trans parts of the chain tethered to the pore opening. We investigate how the chain length, the size of trans compartment, the magnitude of adsorption potential, and the extent of excluded volume interactions affect the translocation time and its distribution. Interplay of these factors brings about a variety of different translocation regimes. We show that excluded volume interactions within a certain range of adsorption potentials can cause a local minimum on the free energy landscape, which is absent for ideal chains. The adsorption potential always leads to the decrease of the free energy barrier, increasing the probability of successful translocation. However, the translocation time depends non-monotonically of the magnitude of adsorption potential. Our calculations predict the existence of the critical magnitude of adsorption potential, which separates favorable and unfavorable regimes of translocation. PMID:22697566

  9. Continuous water treatment by adsorption and electrochemical regeneration.

    PubMed

    Mohammed, F M; Roberts, E P L; Hill, A; Campen, A K; Brown, N W

    2011-05-01

    This study describes a process for water treatment by continuous adsorption and electrochemical regeneration using an air-lift reactor. The process is based on the adsorption of dissolved organic pollutants onto an adsorbent material (a graphite intercalation compound, Nyex(®)1000) and subsequent electrochemical regeneration of the adsorbent leading to oxidation of the adsorbed pollutant. Batch experiments were carried out to determine the adsorption kinetics and equilibrium isotherm for adsorption of a sample contaminant, the organic dye Acid Violet 17. The adsorbent circulation rate, the residence time distribution (RTD) of the reactor, and treatment by continuous adsorption and electrochemical regeneration were studied to investigate the process performance. The RTD behaviour could be approximated as a continuously stirred tank. It was found that greater than 98% removal could be achieved for continuous treatment by adsorption and electrochemical regeneration for feed concentrations of up to 300 mg L(-1). A steady state model has been developed for the process performance, assuming full regeneration of the adsorbent in the electrochemical cell. Experimental data and modelled predictions (using parameters for the adsorbent circulation rate, adsorption kinetics and isotherm obtained experimentally) of the dye removal achieved were found to be in good agreement. PMID:21511325

  10. Multisite adsorption of cadmium on goethite

    SciTech Connect

    Venema, P.; Hiemstra, T.; Riemsdijk, W.H. van

    1996-11-10

    Recently a new general ion adsorption model has been developed for ion binding to mineral surfaces (Hiemstra and van Riemsdijk, 1996). The model uses the Pauling concept of charge distribution (CD) and is an extension of the multi-site complexation (MUSIC) approach. In the CD-MUSIC model the charge of an adsorbing ion that forms an inner sphere complex is distributed over its ligands, which are present in two different electrostatic planes. In this paper the authors have applied the CD-MUSIC model to the adsorption of metal cations, using an extended data set for cadmium adsorbing on goethite. The adsorption of cadmium and the cadmium-proton exchange ratio were measured as function of metal ion concentration, pH, and ionic strength. The data could be described well, taking into account the surface heterogeneity resulting from the presence of two different crystal planes (the dominant 110 face and the minor 021 face). The surface species used in the model are consistent with recent EXAFS data. In accordance with the EXAFS results, high-affinity complexes at the 021 face were used in the model.

  11. Aqueous mercury adsorption by activated carbons.

    PubMed

    Hadi, Pejman; To, Ming-Ho; Hui, Chi-Wai; Lin, Carol Sze Ki; McKay, Gordon

    2015-04-15

    Due to serious public health threats resulting from mercury pollution and its rapid distribution in our food chain through the contamination of water bodies, stringent regulations have been enacted on mercury-laden wastewater discharge. Activated carbons have been widely used in the removal of mercuric ions from aqueous effluents. The surface and textural characteristics of activated carbons are the two decisive factors in their efficiency in mercury removal from wastewater. Herein, the structural properties and binding affinity of mercuric ions from effluents have been presented. Also, specific attention has been directed to the effect of sulfur-containing functional moieties on enhancing the mercury adsorption. It has been demonstrated that surface area, pore size, pore size distribution and surface functional groups should collectively be taken into consideration in designing the optimal mercury removal process. Moreover, the mercury adsorption mechanism has been addressed using equilibrium adsorption isotherm, thermodynamic and kinetic studies. Further recommendations have been proposed with the aim of increasing the mercury removal efficiency using carbon activation processes with lower energy input, while achieving similar or even higher efficiencies. PMID:25644627

  12. Random sequential adsorption of tetramers

    NASA Astrophysics Data System (ADS)

    Cieśla, Michał

    2013-07-01

    Adsorption of a tetramer built of four identical spheres was studied numerically using the random sequential adsorption (RSA) algorithm. Tetramers were adsorbed on a two-dimensional, flat and homogeneous surface. Two different models of the adsorbate were investigated: a rhomboid and a square one; monomer centres were put on vertices of rhomboids and squares, respectively. Numerical simulations allow us to establish the maximal random coverage ratio as well as the available surface function (ASF), which is crucial for determining kinetics of the adsorption process. These results were compared with data obtained experimentally for KfrA plasmid adsorption. Additionally, the density autocorrelation function was measured.

  13. Species differences in kidney necrosis and DNA damage, distribution and glutathione-dependent metabolism of 1,2-dibromo-3-chloropropane (DBCP).

    PubMed

    Søderlund, E J; Låg, M; Holme, J A; Brunborg, G; Omichinski, J G; Dahl, J E; Nelson, S D; Dybing, E

    1990-04-01

    Species differences and mechanisms of 1,2-dibromo-3-chloropropane (DBCP) nephrotoxicity were investigated by studying DBCP renal necrosis and DNA damage, distribution and glutathione-dependent metabolism in rats, mice, hamsters and guinea pigs. Extensive renal tubular necrosis was observed in rats 48 hr after a single intraperitoneal administration (21-170 mumol/kg) of DBCP. Significantly less necrosis was found in mice and guinea pigs, whereas no renal damage was evident (less than 680 mumol/kg) in hamsters. The activation of DBCP to DNA damaging intermediates in vivo, as measured by alkaline elution of DNA isolated from kidney nuclei 60 min. after intraperitoneal injection of DBCP, was compared in all four species. Distinct DNA damage was detected in rats, mice and hamsters as early as 10 min. after administration of DBCP and within 30 min. in guinea pigs. Rats and guinea pigs showed similar sensitivity towards DBCP-induced DNA damage (extensive DNA damage greater than 21 mumol/kg DBCP), whereas in mice and hamsters a 10-50 times higher DBCP dose was needed to cause a similar degree of DNA damage. Renal DBCP concentrations at various time-points (20 min., 1, 3 and 8 hr) after intraperitoneal administration (85 mumol/kg) revealed that the initial (20 min.) DBCP concentration was substantially higher in rats and guinea pigs compared to the other two species. Furthermore, kidney elimination of DBCP occurred at a significantly lower rate in rats than in mice, hamsters and guinea pigs.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2371234

  14. Comprehensive kinetics of triiodothyronine production, distribution, and metabolism in blood and tissue pools of the rat using optimized blood-sampling protocols.

    PubMed

    DiStefano, J J; Jang, M; Malone, T K; Broutman, M

    1982-01-01

    We have determined estimates for 24 physiological parameters of production, interpool transport, distribution, and metabolism of T3 in the major T3 pools of the unanesthetized male Sprague-Dawley rat, from blood-borne data and a comprehensive model and analysis of this system. Most of these indices have previously been unavailable. Whereas only 3% (2 ng/100 g BW) of the total body T3 pool (74 ng/100 g BW) is in plasma, the composite of slowly equilibrating (slow) tissue pools (e.g. muscle, skin, and brain) appears to contain most of the T3, 76% (57 ng/100 g BW) of the total. The composite of rapidly equilibrating (fast) tissue pools (e.g. liver and kidney) contains the remaining 19% (16 ng/100 g BW). The total body T3 production rate is 0.12 ng/100 g BW . min, and we estimate that about half of this emanates directly from T4 in the slow pools, whereas the remainder is derived from both thyroidal secretion and T4 to T3 conversion in the fast pools. Our results also indicate that T3 molecules spend an average of only 0.5 min in transit each time through plasma, whereas the single pass mean transit times in fast and slow tissue pools (the times available for hormone action) are 10 times and 200 times greater. In contrast, the mean residence time for T3 in the entire system is greater than 12 h despite the extremely rapid early disappearance of injected T3 from plasma. To obtain the required accuracy, we used a novel optimization approach for choosing blood-sampling schedules (1, 4, 44, 202, and 600 min), a remarkably small number of sample times, and each was adjustable by about +/- 20% without effect on optimized parameter accuracies. PMID:7053984

  15. Disorders of Carbohydrate Metabolism

    MedlinePlus

    ... Metabolic Disorders Disorders of Carbohydrate Metabolism Disorders of Amino Acid Metabolism Disorders of Lipid Metabolism Carbohydrates are sugars. ... Metabolic Disorders Disorders of Carbohydrate Metabolism Disorders of Amino Acid Metabolism Disorders of Lipid Metabolism NOTE: This is ...

  16. Rethinking Critical Adsorption

    NASA Astrophysics Data System (ADS)

    Franck, Carl; Peach, Sarah; Polak, Robert D.

    1996-03-01

    Recent reflectivity experiments on near-critical mixtures of carbon disulfide and nitromethane contained in glass cells footnote Niraj S. Desai, Sarah Peach, and Carl Franck, Phys. Rev. E 52, 4129 (1995) have shown that preferential adsorption of one liquid component onto the wall can be controlled by chemical modification of the glass. The glass was treated with varying amounts of hexamethyldisilazane to decrease surface polarity and therefore enhance the adsorption of carbon disulfide in a surprisingly continuous way. The effect of the glass wall on the local liquid composition can be described by two different scaling hypotheses: using a short range field on the liquid closest to the wall, or pinning the amplitude of the order parameter at the surface. We have found that only the second approach is consistent with the experimental data, although this is difficult to reconcile with observed wetting critical phenomena. We also have reexamined the issue of substrate inhomogeneity and conclude that the substrates were indeed homogeneous on relevant length scales. Supported by the NSF under DMR-9320910 and the central facilities of the Materials Science Center at Cornell University.

  17. Adsorption behaviour of bulgur.

    PubMed

    Erbaş, Mustafa; Aykın, Elif; Arslan, Sultan; Durak, Atike N

    2016-03-15

    The aim of this research was to determine the adsorption behaviour of bulgur. Three different particle sizes (2adsorption, because of %E values lower than 10%. Bulgur must be stored below 70% relative humidity and with less than 10 g water per 100 g of dry mater. PMID:26575716

  18. Global versus local adsorption selectivity

    NASA Astrophysics Data System (ADS)

    Pauzat, Françoise; Marloie, Gael; Markovits, Alexis; Ellinger, Yves

    2015-10-01

    The origin of the enantiomeric excess found in the amino acids present in the organic matter of carbonaceous meteorites is still unclear. Selective adsorption of one of the two enantiomers existing after a racemic formation could be part of the answer. Hereafter we report a comparative study of the adsorption of the R and S enantiomers of α-alanine and lactic acid on the hydroxylated { } chiral surface of α-quartz using numerical simulation techniques. Structurally different adsorption sites were found with opposite R versus S selectivity for the same molecule-surface couple, raising the problem of whether to consider adsorption as a local property or as a global response characteristic of the whole surface. To deal with the second term of this alternative, a statistical approach was designed, based on the occurrence of each adsorption site whose energy was calculated using first principle periodic density functional theory. It was found that R-alanine and S-lactic acid are the enantiomers preferentially adsorbed, even if the adsorption process on the quartz { } surface stays with a disappointingly poor enantio-selectivity. Nevertheless, it highlighted the important point that considering adsorption as a global property changes perspectives in the search for more efficient enantio-selective supports and more generally changes the way to apprehend adsorption processes in astro-chemistry/biology.

  19. Liquid-Phase Adsorption Fundamentals.

    ERIC Educational Resources Information Center

    Cooney, David O.

    1987-01-01

    Describes an experiment developed and used in the unit operations laboratory course at the University of Wyoming. Involves the liquid-phase adsorption of an organic compound from aqueous solution on activated carbon, and is relevant to adsorption processes in general. (TW)

  20. ADSORPTION MEDIA FOR ARSENIC REMOVAL

    EPA Science Inventory

    Presentation will discuss the use of adsorptive media for the removal of arsenic from drinking water. Presentation is a fundamental discussion on the use of adsorptive media for arsenic removal and includes information from several EPA field studies on removal of arsenic from dr...

  1. A comparative adsorption study: 17β-estradiol onto aerobic granular sludge and activated sludge.

    PubMed

    Zheng, Xiao-ying; He, Yu-jie; Chen, Wei; Wang, Ming-yang; Cao, Su-lan; Ni, Ming; Chen, Yu

    2016-01-01

    Adsorption plays a significant role in removing hydrophobic 17β-estradiol (E2) from wastewater. Batch experiments were conducted to compare the adsorption of E2 onto activated aerobic granular sludge (AGS) and activated sludge (AS), and features evaluated included the adsorption kinetics, thermodynamics, and influence of other environmental factors. By using a non-chemical wet-heat technique, both AGS and AS were treated to inactivated status. Then, after loading E2, the adsorption equilibrium capacity of the AGS was found to be greater than that of the AS at the same initial concentration of E2. Moreover, both the adsorption processes corresponded to a pseudo-second-order kinetic model; the adsorption rate constant of AGS was found to be higher and the half-adsorption time was shorter than that of AS. Next, evaluations of adsorption isotherms and thermodynamics indicated that the adsorption process was mainly a physical process. Lower temperatures facilitated a higher equilibrium adsorption capacity. However, the adsorption binding sites of AGS were distributed more uniformly at higher temperature, in contrast to the distribution found for AS. Finally, acidic conditions and an appropriate ionic strength (0.4 mol/L) were found to be particularly conducive to the adsorption process. Overall, the results showed that AGS has the potential to adsorb E2 with significant efficiency, thereby offering a new and more efficient means of treating E2 and trace oestrogens in wastewater. PMID:26209151

  2. Physical Adsorption of Gases on Heterogeneous Solids and Equilibrium Studies of the Pressure Swing Adsorption Process.

    NASA Astrophysics Data System (ADS)

    Lu, Xiaochun

    1990-01-01

    Adsorption isotherms of ethane, propane, and n -butane on two polystyrene adsorbents and two activated carbons were measured at 0, 25, and 40^ circC. A dynamic chromatographic experimental system was used to measure the transmission curves of gases through a packed bed. The transmission is defined as the ratio of the adsorbate concentration at the bed outlet to that at the bed inlet. A mass-balance equation was used to calculate the solid-phase concentration and the dimensionless adsorption capacity. The structural and energetic heterogeneities of microporous adsorbents were explored by means of Dubinin's Theory of Volume Filling of Micropores (TVFM) and by a modified TVFM. The structural heterogeneity of a microporous adsorbent refers to the non-uniformity of the pore sizes and pore shapes. In polystyrene adsorbents, these non -uniform pores were formed by different copolymerization of monomers; while in activated carbons, these non-uniform pores were formed in the processes of carbonization and activation. The energetic heterogeneities of a microporous adsorbent comes from the structural heterogeneity as well as from the various atoms and functional groups exposed at the pore surface, the impurities strongly bound to the surface, and the irregularities in the crystallographical structure of the surface. Dubinin's original TVFM applies well in structurally homogeneous or weakly-heterogeneous microporous activated carbons; however, fits of experimental isotherms to the Dubinin-Radushkevich equation reveal deviations for structurally -heterogeneous adsorbents. We extended Dubinin's TVFM to the case of structurally-heterogeneous adsorbents by using an overall integral isotherm equation. A gamma-function type micropore-size distribution was used and a three-parameter isotherm equation was obtained. The experimental isotherms on activated carbons were fitted well by this isotherm equation. We characterized eight different activated carbons with the three

  3. Adsorption and co-adsorption of diclofenac and Cu(II) on calcareous soils.

    PubMed

    Graouer-Bacart, Mareen; Sayen, Stéphanie; Guillon, Emmanuel

    2016-02-01

    Pharmaceuticals are emerging contaminants and their presence in different compartments of the environment has been detected in many countries. In this study, laboratory batch experiments were conducted to characterize the adsorption of diclofenac, a widely used non-steroidal anti-inflammatory drug, on six calcareous soils. The adsorption of diclofenac was relatively low, which may lead to a risk of groundwater contamination and plant uptake. A correlation between the soil-water distribution coefficient Kd and soil characteristics has been highlighted. Indeed, diclofenac adsorption as a function of soil organic matter content (% OM) and Rt=% CaCO3/% OM was successfully described through a simple empirical model, indicating the importance of considering the inhibiting effect of CaCO3 on OM retention properties for a better assessment of diclofenac fate in the specific case of calcareous soils. The simultaneous co-adsorption of diclofenac and copper - a ubiquitous pollutant in the environment - at the water/soil interface, was also investigated. It appeared quite unexpectedly that copper did not have a significant influence on diclofenac retention. PMID:26599281

  4. High temperature adsorption measurements

    SciTech Connect

    Bertani, R.; Parisi, L.; Perini, R.; Tarquini, B.

    1996-01-24

    Adsorption phenomena are a rich and rather new field of study in geothermal research, in particular at very high temperature. ENEL is interested in the exploitation of geothermal regions with superheated steam, and it is important to understand the behavior of water-rock interaction. We have analyzed in the 170-200 °C temperature range four samples of Monteverdi cuttings; the next experimental effort will be at 220 °C and over in 1996. The first results of the 1995 runs are collected in this paper. We can highlight four main items: 1. At relative pressures over 0.6 the capillarity forces are very important. 2. There is no significant temperature effect. 3. Adsorbed water can be present, and it is able to multiply by a factor of 15 the estimated reserve of super-heated steam only. 4. Pores smaller than 15 Å do not contribute to the adsorbed mass.

  5. High temperature adsorption measurements

    SciTech Connect

    Bertani, R.; Parisi, L.; Perini, R.; Tarquini, B.

    1996-12-31

    Adsorption phenomena are a rich and rather new field of study in geothermal research, in particular at very high temperature. ENEL is interested in the exploitation of geothermal regions with super-heated steam, and it is important to understand the behavior of water-rock interaction. We have analyzed in the 170-200{degrees}C temperature range four samples of Monteverdi cuttings; the next experimental effort will be at 220{degrees}C and over in 1996. The first results of the 1995 runs are collected in this paper. We can highlight four main items: (1) At relative pressures over 0.6 the capillarity forces are very important. (2) There is no significant temperature effect. (3) Adsorbed water can be present, and it is able to multiply by a factor of 15 the estimated reserve of super-heated steam only. (4) Pores smaller than 15 {Angstrom} do not contribute to the adsorbed mass.

  6. Chromium adsorption by lignin

    SciTech Connect

    Lalvani, S.B.; Huebner, A.; Wiltowski, T.S.

    2000-01-01

    Hexavalent chromium is a known carcinogen, and its maximum contamination level in drinking water is determined by the US Environmental Protection Agency (EPA). Chromium in the wastewaters from plating and metal finishing, tanning, and photographic industries poses environmental problems. A commercially available lignin was used for the removal of hexavalent as well as trivalent chromium from aqueous solution. It is known that hexavalent chromium is present as an anionic species in the solution. It was found that lignin can remove up to 63% hexavalent and 100% trivalent chromium from aqueous solutions. The removal of chromium ions was also investigated using a commercially available activated carbon. This absorbent facilitated very little hexavalent and almost complete trivalent chromium removal. Adsorption isotherms and kinetics data on the metal removal by lignin and activated carbon are presented and discussed.

  7. Metabolic Disorders

    MedlinePlus

    ... as your liver, muscles, and body fat. A metabolic disorder occurs when abnormal chemical reactions in your body ... that produce the energy. You can develop a metabolic disorder when some organs, such as your liver or ...

  8. [Characteristics of Adsorption Leaching and Influencing Factors of Dimethyl Phthalate in Purple Soil].

    PubMed

    Wang, Qiang; Song, Jiao-yan; Zeng, Wei; Wang, Fa

    2016-02-15

    The typical soil-purple soil in Three Gorges Reservoir was the tested soil, the characteristics of adsorption leaching of dimethyl phthalate (DMP) in contaminated water by the soil, and the influencing factors in the process were conducted using soil column leaching experiment. The results showed that the parabolic equation was the best equation describing adsorption kinetics of DMP by soils. The concentration of DMP in the leaching solution had significant effect on the adsorption amounts of DMP. With the increasing concentration of DMP in the leaching solution, the adsorption capacities of DMP by purple soil increased linearly. The ionic strength and pH in leaching solution had significant effects on adsorption of DMP. On the whole, increasing of the ionic strength restrained the adsorption. The adsorption amounts at pH 5.0-7.0 were more than those under other pH condition. The addition of exogenous organic matter (OM) in purple soil increased the adsorption amount of DMP by purple soil. However, the adsorption amount was less than those with other addition amounts of exogenous OM when the addition of exogenous OM was too high (> or = 30 g x kg(-1)). The addition of surfactant sodium dodecylbenzene sulfonic acid (SDBS) in purple soil increased the adsorption amount of DMP by purple soil. The adsorption amount was maximal when the addition amount of SDBS was 50 mg x kg(-1). However, the adsorption amounts decreased with increasing addition amounts of SDBS although the adsorption amounts were still more than that of the control group, and the adsorption amount was almost equal to that of the control group when the addition amount of SDBS was 800 mg x kg(-1). Continuous leaching time affected the vertical distribution of DMP in the soil column. When the leaching time was shorter, the upper soil column adsorbed more DMP, while the DMP concentrations in upper and lower soil columns became similar with the extension of leaching time. PMID:27363166

  9. TCE adsorption by GAC preloaded with humic substances

    SciTech Connect

    Kilduff, J.E.; Karanfil, T.; Weber, W.J. Jr.

    1998-05-01

    Adsorption of trichloroethylene (TCE) by activated carbon preloaded with humic and fulvic acids was studied under several conditions in completely mixed batch systems. The authors investigated how molecular weight and molecular-weight distribution of preloaded humic substances affected subsequent adsorption of TCE. The capacity of carbon to adsorb TCE was most greatly reduced in carbon that was preloaded with humic acid components having molecular weights less than about 1,400 g/mol as polystyrene sulfonate. The adsorption capacity was greatly reduced in carbon that was preloaded with whole humic mixtures in which lower molecular weights predominated. The energy distributions of adsorbent indicate that preloaded compounds preferentially occupy high-energy sites, making them inaccessible to subsequently encountered TCE.

  10. Adsorption of nanoparticles at the solid-liquid interface.

    PubMed

    Brenner, Thorsten; Paulus, Michael; Schroer, Martin A; Tiemeyer, Sebastian; Sternemann, Christian; Möller, Johannes; Tolan, Metin; Degen, Patrick; Rehage, Heinz

    2012-05-15

    The adsorption of differently charged nanoparticles at liquid-solid interfaces was investigated by in situ X-ray reflectivity measurements. The layer formation of positively charged maghemite (γ-Fe(2)O(3)) nanoparticles at the aqueous solution-SiO(2) interface was observed while negatively charged gold nanoparticles show no adsorption at this interface. Thus, the electrostatic interaction between the particles and the charged surface was determined as the driving force for the adsorption process. The data analysis shows that a logarithmic particle size distribution describes the density profile of the thin adsorbed maghemite layer. The size distribution in the nanoparticle solution determined by small angle X-ray scattering shows an average particle size which is similar to that found for the adsorbed film. The formed magehemite film exhibits a rather high stability. PMID:22386203

  11. CO2 adsorption on chemically modified activated carbon.

    PubMed

    Caglayan, Burcu Selen; Aksoylu, A Erhan

    2013-05-15

    CO2 adsorption capacity of a commercial activated carbon was improved by using HNO3 oxidation, air oxidation, alkali impregnation and heat treatment under helium gas atmosphere. The surface functional groups produced were investigated by diffuse reflectance infrared Fourier transform spectrometer (DRIFTS). CO2 adsorption capacities of the samples were determined by gravimetric analyses for 25-200°C temperature range. DRIFTS studies revealed the formation of carboxylic acid groups on the HNO3 oxidized adsorbents. Increased aromatization and uniform distribution of the Na particles were observed on the samples prepared by Na2CO3 impregnation onto HNO3 oxidized AC support. The adsorption capacities of the nonimpregnated samples were increased by high temperature helium treatments or by increasing the adsorption temperature; both leading to decomposition of surface oxygen groups, forming sites that can easily adsorb CO2. The adsorption capacity loss due to cyclic adsorption/desorption procedures was overcome with further surface stabilization of Na2CO3 modified samples with high temperature He treatments. With Na2CO3 impregnation the mass uptakes of the adsorbents at 20 bars and 25 °C were improved by 8 and 7 folds and at 1 bar were increased 15 and 16 folds, on the average, compared to their air oxidized and nitric acid oxidized supports, respectively. PMID:23500788

  12. Probing the Adsorption Behavior of 4,5-Diazafluoren-9-one and Its Schiff Base Derivatives on SIlver and Gold Nanosurfaces Using Raman Spectroscopy, Density Functional Theory and Potential Energy Distribution Calculations

    NASA Astrophysics Data System (ADS)

    McCoy, Rhonda Patrice

    4,5-Diazafluoren-9-one (DAFO) is an aromatic ketone synthesized by oxidizing 1,10-phenanthroline with potassium permanganate. In this present study, the Raman spectra of DAFO in the solid and solution states were recorded in the 100-2000 cm-1 spectral region using 1064, 633, 532, and 514 nm excitation sources. A normal mode analysis of DAFO was performed using density functional theory; the BLYP and B3LYP functionals, each with the 6-31G(d) and 6-311(d) basis sets were employed. The fundamental modes on the Raman spectrum of DAFO were assigned with the appropriate symmetry element using the BLYP functional and 6-31G(d) basis set. The vibrational modes were described and quantified by potential energy distribution calculations. The Raman frequencies for the solid and solution spectra were compared; the observed frequency shifts are attributed to hydrogen bonding or dipole-dipole interactions occurring between the solvent and DAFO ligand. To further assess solute-solvent interactions the UV-vis spectra of DAFO was obtained in hydrogen bonding, polar aprotic, and non-polar solvents. The fine structure of the band observed at lambda max becomes more resolved as solvent polarity decreases, therefore confirming solute-solvent interactions in polar solvents. A silver complex of DAFO was synthesized with the intent of understanding how coordination affected the Raman frequencies. The bands assigned to pyridine ring bending, nu(C=N), and nu(C=O) were shifted because of coordination. These shifts have been attributed to the molecule being perturbed because of coordination. Therefore, the Ag-DAFO complex was analyzed by X-Ray diffraction and the molecular geometries of the free and coordinated ligand were compared. The resolved crystalline structure revealed the silver ion coordinated DAFO using the lone pairs of electrons from the nitrogens in the pyridine ring. Analysis of the molecular geometry revealed the C=O bond increases in double bond character and the C5-C14 bond

  13. Adsorption of polymeric brushes: Bridging

    NASA Astrophysics Data System (ADS)

    Johner, Albert; Joanny, Jean-François

    1992-04-01

    We study the adsorption of grafted polymer layers on a planar surface parallel to the grafting surface. The layer consists of two types of chains: nonadsorbed chains with a free end and adsorbed chains forming bridges between the two plates. In the limit of strong adsorption a dead zone exists in the vicinity of the adsorbing plate; its size increases with the adsorption strength. Two adsorption mechanisms are possible: adsorption of the last monomer only and adsorption of all the monomers. In both cases the adsorption regimes at equilibrium (when no external force acts on the plates) are discussed within the framework of the self-consistent mean-field theory. We also give scaling laws taking into account excluded volume correlations. Finally, we consider situations where a finite external force, either tangential or normal to the plates, is applied on the adsorbing plate. Pulling and tangential forces both reduce the fraction of bridges and eventually lead to rupture, whereas compressional forces favor bridging. For normal forces, force vs distance profiles between planes and crossed cylinders are given.

  14. Particle-scale CO2 adsorption kinetics modeling considering three reaction mechanisms

    SciTech Connect

    Suh, Dong-Myung; Sun, Xin

    2013-09-01

    In the presence of water (H2O), dry and wet adsorptions of carbon dioxide (CO2) and physical adsorption of H2O happen concurrently in a sorbent particle. The three reactions depend on each other and have a complicated, but important, effect on CO2 capturing via a solid sorbent. In this study, transport phenomena in the sorbent were modeled, including the tree reactions, and a numerical solving procedure for the model also was explained. The reaction variable distribution in the sorbent and their average values were calculated, and simulation results were compared with experimental data to validate the proposed model. Some differences, caused by thermodynamic parameters, were observed between them. However, the developed model reasonably simulated the adsorption behaviors of a sorbent. The weight gained by each adsorbed species, CO2 and H2O, is difficult to determine experimentally. It is known that more CO2 can be captured in the presence of water. Still, it is not yet known quantitatively how much more CO2 the sorbent can capture, nor is it known how much dry and wet adsorptions separately account for CO2 capture. This study addresses those questions by modeling CO2 adsorption in a particle and simulating the adsorption process using the model. As adsorption temperature changed into several values, the adsorbed amount of each species was calculated. The captured CO2 in the sorbent particle was compared quantitatively between dry and wet conditions. As the adsorption temperature decreased, wet adsorption increased. However, dry adsorption was reduced.

  15. Random sequential adsorption on fractals

    NASA Astrophysics Data System (ADS)

    Ciesla, Michal; Barbasz, Jakub

    2012-07-01

    Irreversible adsorption of spheres on flat collectors having dimension d < 2 is studied. Molecules are adsorbed on Sierpinski's triangle and carpet-like fractals (1 < d < 2), and on general Cantor set (d < 1). Adsorption process is modeled numerically using random sequential adsorption (RSA) algorithm. The paper concentrates on measurement of fundamental properties of coverages, i.e., maximal random coverage ratio and density autocorrelation function, as well as RSA kinetics. Obtained results allow to improve phenomenological relation between maximal random coverage ratio and collector dimension. Moreover, simulations show that, in general, most of known dimensional properties of adsorbed monolayers are valid for non-integer dimensions.

  16. Random sequential adsorption on fractals.

    PubMed

    Ciesla, Michal; Barbasz, Jakub

    2012-07-28

    Irreversible adsorption of spheres on flat collectors having dimension d < 2 is studied. Molecules are adsorbed on Sierpinski's triangle and carpet-like fractals (1 < d < 2), and on general Cantor set (d < 1). Adsorption process is modeled numerically using random sequential adsorption (RSA) algorithm. The paper concentrates on measurement of fundamental properties of coverages, i.e., maximal random coverage ratio and density autocorrelation function, as well as RSA kinetics. Obtained results allow to improve phenomenological relation between maximal random coverage ratio and collector dimension. Moreover, simulations show that, in general, most of known dimensional properties of adsorbed monolayers are valid for non-integer dimensions. PMID:22852643

  17. Centrifugal Adsorption Cartridge System

    NASA Technical Reports Server (NTRS)

    Gonda, Steve R.; Tsao, Yow-Min D.; Lee, Wenshan

    2004-01-01

    The centrifugal adsorption cartridge system (CACS) is an apparatus that recovers one or more bioproduct(s) from a dilute aqueous solution or suspension flowing from a bioreactor. The CACS can be used both on Earth in unit gravity and in space in low gravity. The CACS can be connected downstream from the bioreactor; alternatively, it can be connected into a flow loop that includes the bioreactor so that the liquid can be recycled. A centrifugal adsorption cartridge in the CACS (see figure) includes two concentric cylinders with a spiral ramp between them. The volume between the inner and outer cylinders, and between the turns of the spiral ramp is packed with an adsorbent material. The inner cylinder is a sieve tube covered with a gas-permeable, hydrophobic membrane. During operation, the liquid effluent from the bioreactor is introduced at one end of the spiral ramp, which then constrains the liquid to flow along the spiral path through the adsorbent material. The spiral ramp also makes the flow more nearly uniform than it would otherwise be, and it minimizes any channeling other than that of the spiral flow itself. The adsorbent material is formulated to selectively capture the bioproduct(s) of interest. The bioproduct(s) can then be stored in bound form in the cartridge or else eluted from the cartridge. The centrifugal effect of the spiral flow is utilized to remove gas bubbles from the liquid. The centrifugal effect forces the bubbles radially inward, toward and through the membrane of the inner cylinder. The gas-permeable, hydrophobic membrane allows the bubbles to enter the inner cylinder while keeping the liquid out. The bubbles that thus enter the cylinder are vented to the atmosphere. The spacing between the ramps determines rate of flow along the spiral, and thereby affects the air-bubble-removal efficiency. The spacing between the ramps also determines the length of the fluid path through the cartridge adsorbent, and thus affects the bioproduct

  18. Bromide Adsorption by Reference Minerals and Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bromide, Br-, adsorption behavior was investigated on amorphous Al and Fe oxide, montmorillonite, kaolinite, and temperate and tropical soils. Bromide adsorption decreased with increasing solution pH with minimal adsorption occurring above pH 7. Bromide adsorption was higher for amorphous oxides t...

  19. Effects of Insulin-Like Growth Factor (IGF)-I/IGF-Binding Protein-3 Treatment on Glucose Metabolism and Fat Distribution in Human Immunodeficiency Virus-Infected Patients with Abdominal Obesity and Insulin Resistance

    PubMed Central

    Rao, Madhu N.; Mulligan, Kathleen; Tai, Viva; Wen, Michael J.; Dyachenko, Artem; Weinberg, Melissa; Li, Xiaojuan; Lang, Thomas; Grunfeld, Carl; Schwarz, Jean-Marc; Schambelan, Morris

    2010-01-01

    Context: HIV-infected patients on antiretroviral therapy are at increased risk for excess visceral adiposity and insulin resistance. Treatment with GH decreases visceral adiposity but worsens glucose metabolism. IGF-I, which mediates many of the effects of GH, improves insulin sensitivity in HIV-negative individuals. Objective: Our objective was to determine whether IGF-I, complexed to its major binding protein, IGF-binding protein-3 (IGFBP-3), improves glucose metabolism and alters body fat distribution in HIV-infected patients with abdominal obesity and insulin resistance. Methods: We conducted a pilot, open-label study in 13 HIV-infected men with excess abdominal adiposity and insulin resistance to assess the effect of 3 months of treatment with IGF-I/IGFBP-3 on glucose metabolism and fat distribution. Glucose metabolism was assessed by oral glucose tolerance test and hyperinsulinemic-euglycemic clamp. Endogenous glucose production (EGP), gluconeogenesis, whole-body lipolysis, and de novo lipogenesis (DNL) were measured with stable isotope infusions. Body composition was assessed by dual-energy x-ray absorptiometry and abdominal computed tomography scan. Results: Glucose tolerance improved and insulin-mediated glucose uptake increased significantly during treatment. EGP increased under fasting conditions, and suppression of EGP by insulin was blunted. Fasting triglycerides decreased significantly in association with a decrease in hepatic DNL. Lean body mass increased and total body fat decreased, whereas visceral adipose tissue did not change. Conclusions: Treatment with IGF-I/IGFBP-3 improved whole-body glucose uptake and glucose tolerance, while increasing hepatic glucose production. Fasting triglycerides improved, reflecting decreased DNL, and visceral adiposity was unchanged. PMID:20610601

  20. Molecular adsorption on graphene

    NASA Astrophysics Data System (ADS)

    Kong, Lingmei; Enders, Axel; Rahman, Talat S.; Dowben, Peter A.

    2014-11-01

    Current studies addressing the engineering of charge carrier concentration and the electronic band gap in epitaxial graphene using molecular adsorbates are reviewed. The focus here is on interactions between the graphene surface and the adsorbed molecules, including small gas molecules (H2O, H2, O2, CO, NO2, NO, and NH3), aromatic, and non-aromatic molecules (F4-TCNQ, PTCDA, TPA, Na-NH2, An-CH3, An-Br, Poly (ethylene imine) (PEI), and diazonium salts), and various biomolecules such as peptides, DNA fragments, and other derivatives. This is followed by a discussion on graphene-based gas sensor concepts. In reviewing the studies of the effects of molecular adsorption on graphene, it is evident that the strong manipulation of graphene’s electronic structure, including p- and n-doping, is not only possible with molecular adsorbates, but that this approach appears to be superior compared to these exploiting edge effects, local defects, or strain. However, graphene-based gas sensors, albeit feasible because huge adsorbate-induced variations in the relative conductivity are possible, generally suffer from the lack of chemical selectivity.

  1. Molecular adsorption on graphene.

    PubMed

    Kong, Lingmei; Enders, Axel; Rahman, Talat S; Dowben, Peter A

    2014-11-01

    Current studies addressing the engineering of charge carrier concentration and the electronic band gap in epitaxial graphene using molecular adsorbates are reviewed. The focus here is on interactions between the graphene surface and the adsorbed molecules, including small gas molecules (H(2)O, H(2), O(2), CO, NO(2), NO, and NH(3)), aromatic, and non-aromatic molecules (F4-TCNQ, PTCDA, TPA, Na-NH(2), An-CH(3), An-Br, Poly (ethylene imine) (PEI), and diazonium salts), and various biomolecules such as peptides, DNA fragments, and other derivatives. This is followed by a discussion on graphene-based gas sensor concepts. In reviewing the studies of the effects of molecular adsorption on graphene, it is evident that the strong manipulation of graphene's electronic structure, including p- and n-doping, is not only possible with molecular adsorbates, but that this approach appears to be superior compared to these exploiting edge effects, local defects, or strain. However, graphene-based gas sensors, albeit feasible because huge adsorbate-induced variations in the relative conductivity are possible, generally suffer from the lack of chemical selectivity. PMID:25287516

  2. Short-Cycle Adsorption Refrigerator

    NASA Technical Reports Server (NTRS)

    Chan, C. K.

    1988-01-01

    Modular adsorption/Joule-Thomson-effect refrigerator offers fast regeneration; adsorption/desorption cycle time expected to be 1 minute. Pressurized hydrogen generated by bank of compressor modules during heating phase passes through system of check valves and expands in Joule-Thomson junction as it enters refrigeration chamber. Hydrogen absorbs heat from load before it is sucked out by another bank of compressor modules in cooling phase.

  3. Ion adsorption and its influence on direct current electric field induced deformations of flexoelectric nematic layers

    NASA Astrophysics Data System (ADS)

    Derfel, Grzegorz; Buczkowska, Mariola

    2011-07-01

    The influence of ion adsorption on the behavior of the nematic liquid crystal layers is studied numerically. The homeotropic flexoelectric layer subjected to the dc electric field is considered. Selective adsorption of positive ions is assumed. The analysis is based on the free energy formalism for ion adsorption. The distributions of director orientation angle, electric potential, and ion concentrations are calculated by numerical resolving of suitable torques equations and Poisson equation. The threshold voltages for the deformations are also determined. It was shown that adsorption affects the distributions of both cations and anions. Sufficiently large number of adsorbed ions leads to spontaneous deformation arising without any threshold if the total number of ions creates sufficiently strong electric field with significant field gradients in the neighborhood of electrodes. The spontaneous deformations are favored by strong flexoelectricity, large thickness, large ion concentrations, weak anchoring, and large adsorption energy.

  4. Protein Adsorption in Three Dimensions

    PubMed Central

    Vogler, Erwin A.

    2011-01-01

    Recent experimental and theoretical work clarifying the physical chemistry of blood-protein adsorption from aqueous-buffer solution to various kinds of surfaces is reviewed and interpreted within the context of biomaterial applications, especially toward development of cardiovascular biomaterials. The importance of this subject in biomaterials surface science is emphasized by reducing the “protein-adsorption problem” to three core questions that require quantitative answer. An overview of the protein-adsorption literature identifies some of the sources of inconsistency among many investigators participating in more than five decades of focused research. A tutorial on the fundamental biophysical chemistry of protein adsorption sets the stage for a detailed discussion of the kinetics and thermodynamics of protein adsorption, including adsorption competition between two proteins for the same adsorbent immersed in a binary-protein mixture. Both kinetics and steady-state adsorption can be rationalized using a single interpretive paradigm asserting that protein molecules partition from solution into a three-dimensional (3D) interphase separating bulk solution from the physical-adsorbent surface. Adsorbed protein collects in one-or-more adsorbed layers, depending on protein size, solution concentration, and adsorbent surface energy (water wettability). The adsorption process begins with the hydration of an adsorbent surface brought into contact with an aqueous-protein solution. Surface hydration reactions instantaneously form a thin, pseudo-2D interface between the adsorbent and protein solution. Protein molecules rapidly diffuse into this newly-formed interface, creating a truly 3D interphase that inflates with arriving proteins and fills to capacity within milliseconds at mg/mL bulk-solution concentrations CB. This inflated interphase subsequently undergoes time-dependent (minutes-to-hours) decrease in volume VI by expulsion of either-or-both interphase water and

  5. Metabolic myopathies

    NASA Technical Reports Server (NTRS)

    Martin, A.; Haller, R. G.; Barohn, R.; Blomqvist, C. G. (Principal Investigator)

    1994-01-01

    Metabolic myopathies are disorders of muscle energy production that result in skeletal muscle dysfunction. Cardiac and systemic metabolic dysfunction may coexist. Symptoms are often intermittent and provoked by exercise or changes in supply of lipid and carbohydrate fuels. Specific disorders of lipid and carbohydrate metabolism in muscle are reviewed. Evaluation often requires provocative exercise testing. These tests may include ischemic forearm exercise, aerobic cycle exercise, and 31P magnetic resonance spectroscopy with exercise.

  6. Metabolic ecology.

    PubMed

    Humphries, Murray M; McCann, Kevin S

    2014-01-01

    Ecological theory that is grounded in metabolic currencies and constraints offers the potential to link ecological outcomes to biophysical processes across multiple scales of organization. The metabolic theory of ecology (MTE) has emphasized the potential for metabolism to serve as a unified theory of ecology, while focusing primarily on the size and temperature dependence of whole-organism metabolic rates. Generalizing metabolic ecology requires extending beyond prediction and application of standardized metabolic rates to theory focused on how energy moves through ecological systems. A bibliometric and network analysis of recent metabolic ecology literature reveals a research network characterized by major clusters focused on MTE, foraging theory, bioenergetics, trophic status, and generalized patterns and predictions. This generalized research network, which we refer to as metabolic ecology, can be considered to include the scaling, temperature and stoichiometric models forming the core of MTE, as well as bioenergetic equations, foraging theory, life-history allocation models, consumer-resource equations, food web theory and energy-based macroecology models that are frequently employed in ecological literature. We conclude with six points we believe to be important to the advancement and integration of metabolic ecology, including nomination of a second fundamental equation, complementary to the first fundamental equation offered by the MTE. PMID:24028511

  7. Adsorption-induced fracture of branched macromolecules.

    NASA Astrophysics Data System (ADS)

    Sheiko, Sergei; Sun, Frank; Shirvanyants, David; Rubinstein, Michael; Lee, Hyung-Il; Matyjaszewski, Krzysztof

    2006-03-01

    Recently, we have discovered the remarkable phenomenon that brush-like macromolecules with long side chains undergo scission of the backbone bonds as a result of adsorption onto a substrate. The macromolecule's self-destruction occurs because its side chains stretch the polymer backbone as the macromolecule struggles to reconfigure and maximize the number of contacts with the substrate. We show that the tension imposed by the surface attraction is unevenly distributed over the covalent bonds of the molecular skeleton. Along the brush axis, a major fraction of the tensile force is carried by the backbone, while in the perpendicular direction the tension is distributed over many side chains. Using molecular visualization and computer simulation, we confirmed the first order kinetics and measured the corresponding rate constant, which revealed strong dependence on the attraction to the substrate.

  8. Effect of ferrihydrite crystallite size on phosphate adsorption reactivity.

    PubMed

    Wang, Xiaoming; Li, Wei; Harrington, Richard; Liu, Fan; Parise, John B; Feng, Xionghan; Sparks, Donald L

    2013-09-17

    The influence of crystallite size on the adsorption reactivity of phosphate on 2-line to 6-line ferrihydrites was investigated by combining adsorption experiments, structure and surface analysis, and spectroscopic analysis. X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed that the ferrihydrite samples possessed a similar fundamental structure with a crystallite size varying from 1.6 to 4.4 nm. N2 adsorption on freeze-dried samples revealed that the specific surface area (SSABET) decreased from 427 to 234 m(2) g(-1) with increasing crystallite size and micropore volume (Vmicro) from 0.137 to 0.079 cm(3) g(-1). Proton adsorption (QH) at pH 4.5 and 0.01 M KCl ranged from 0.73 to 0.55 mmol g(-1). Phosphate adsorption capacity at pH 4.5 and 0.01 M KCl for the ferrihydrites decreased from 1690 to 980 μmol g(-1) as crystallite size increased, while the adsorption density normalized to SSABET was similar. Phosphate adsorption on the ferrihydrites exhibited similar behavior with respect to both kinetics and the adsorption mechanism. The kinetics could be divided into three successive first-order stages: relatively fast adsorption, slow adsorption, and a very slow stage. With decreasing crystallite size, ferrihydrites exhibited increasing rate constants per mass for all stages. Analysis of OH(-) release and attenuated total reflectance infrared spectroscopy (ATR-IR) and differential pair distribution function (d-PDF) results indicated that initially phosphate preferentially bound to two Fe-OH2(1/2+) groups to form a binuclear bidentate surface complex without OH(-) release, with smaller size ferrihydrites exchanging more Fe-OH2(1/2+) per mass. Subsequently, phosphate exchanged with both Fe-OH2(1/2+) and Fe-OH(1/2-) with a constant amount of OH(-) released per phosphate adsorbed. Also in this stage binuclear bidentate surface complexes were formed with a P-Fe atomic pair distance of ~3.25 Å. PMID:23992548

  9. Systemic distribution of single-walled carbon nanotubes in a novel model: alteration of biochemical parameters, metabolic functions, liver accumulation, and inflammation in vivo

    PubMed Central

    Principi, Elisa; Girardello, Rossana; Bruno, Antonino; Manni, Isabella; Gini, Elisabetta; Pagani, Arianna; Grimaldi, Annalisa; Ivaldi, Federico; Congiu, Terenzio; De Stefano, Daniela; Piaggio, Giulia; de Eguileor, Magda; Noonan, Douglas M; Albini, Adriana

    2016-01-01

    The increasing use of carbon nanotubes (CNTs) in several industrial applications raises concerns on their potential toxicity due to factors such as tissue penetrance, small dimensions, and biopersistence. Using an in vivo model for CNT environmental exposure, mimicking CNT exposition at the workplace, we previously found that CNTs rapidly enter and disseminate in the organism, initially accumulating in the lungs and brain and later reaching the liver and kidneys via the bloodstream in CD1 mice. Here, we monitored and traced the accumulation of single-walled CNTs (SWCNTs), administered systemically in mice, in different organs and the subsequent biological responses. Using the novel in vivo model, MITO-Luc bioluminescence reporter mice, we found that SWCNTs induce systemic cell proliferation, indicating a dynamic response of cells of both bone marrow and the immune system. We then examined metabolic (water/food consumption and dejections), functional (serum enzymes), and morphological (organs and tissues) alterations in CD1 mice treated with SWCNTs, using metabolic cages, performing serum analyses, and applying histological, immunohistochemical, and ultrastructural (transmission electron microscopy) methods. We observed a transient accumulation of SWCNTs in the lungs, spleen, and kidneys of CD1 mice exposed to SWCNTs. A dose- and time-dependent accumulation was found in the liver, associated with increases in levels of aspartate aminotransferase, alanine aminotransferase and bilirubinemia, which are metabolic markers associated with liver damage. Our data suggest that hepatic accumulation of SWCNTs associated with liver damage results in an M1 macrophage-driven inflammation. PMID:27621623

  10. Systemic distribution of single-walled carbon nanotubes in a novel model: alteration of biochemical parameters, metabolic functions, liver accumulation, and inflammation in vivo.

    PubMed

    Principi, Elisa; Girardello, Rossana; Bruno, Antonino; Manni, Isabella; Gini, Elisabetta; Pagani, Arianna; Grimaldi, Annalisa; Ivaldi, Federico; Congiu, Terenzio; De Stefano, Daniela; Piaggio, Giulia; de Eguileor, Magda; Noonan, Douglas M; Albini, Adriana

    2016-01-01

    The increasing use of carbon nanotubes (CNTs) in several industrial applications raises concerns on their potential toxicity due to factors such as tissue penetrance, small dimensions, and biopersistence. Using an in vivo model for CNT environmental exposure, mimicking CNT exposition at the workplace, we previously found that CNTs rapidly enter and disseminate in the organism, initially accumulating in the lungs and brain and later reaching the liver and kidneys via the bloodstream in CD1 mice. Here, we monitored and traced the accumulation of single-walled CNTs (SWCNTs), administered systemically in mice, in different organs and the subsequent biological responses. Using the novel in vivo model, MITO-Luc bioluminescence reporter mice, we found that SWCNTs induce systemic cell proliferation, indicating a dynamic response of cells of both bone marrow and the immune system. We then examined metabolic (water/food consumption and dejections), functional (serum enzymes), and morphological (organs and tissues) alterations in CD1 mice treated with SWCNTs, using metabolic cages, performing serum analyses, and applying histological, immunohistochemical, and ultrastructural (transmission electron microscopy) methods. We observed a transient accumulation of SWCNTs in the lungs, spleen, and kidneys of CD1 mice exposed to SWCNTs. A dose- and time-dependent accumulation was found in the liver, associated with increases in levels of aspartate aminotransferase, alanine aminotransferase and bilirubinemia, which are metabolic markers associated with liver damage. Our data suggest that hepatic accumulation of SWCNTs associated with liver damage results in an M1 macrophage-driven inflammation. PMID:27621623

  11. Irreversibility and Polymer Adsorption

    NASA Astrophysics Data System (ADS)

    O'Shaughnessy, Ben; Vavylonis, Dimitrios

    2003-02-01

    Physisorption or chemisorption from dilute polymer solutions often entails irreversible polymer-surface bonding. We present a theory of the resultant nonequilibrium layers. While the density profile and loop distribution are the same as for equilibrium layers, the final layer comprises a tightly bound inner part plus an outer part whose chains make only fN surface contacts where N is chain length. The contact fractions f follow a broad distribution, P(f)˜f-4/5, in rather close agreement with strong physisorption experiments [

    H. M. Schneider et al., LangmuirLANGD50743-7463 12, 994 (1996)
    ].

  12. Adsorption of benzene, cyclohexane and hexane on ordered mesoporous carbon.

    PubMed

    Wang, Gang; Dou, Baojuan; Zhang, Zhongshen; Wang, Junhui; Liu, Haier; Hao, Zhengping

    2015-04-01

    Ordered mesoporous carbon (OMC) with high specific surface area and large pore volume was synthesized and tested for use as an adsorbent for volatile organic compound (VOC) disposal. Benzene, cyclohexane and hexane were selected as typical adsorbates due to their different molecular sizes and extensive utilization in industrial processes. In spite of their structural differences, high adsorption amounts were achieved for all three adsorbates, as the pore size of OMC is large enough for the access of these VOCs. In addition, the unusual bimodal-like pore size distribution gives the adsorbates a higher diffusion rate compared with conventional adsorbents such as activated carbon and carbon molecular sieve. Kinetic analysis suggests that the adsorption barriers mainly originated from the difficulty of VOC vapor molecules entering the pore channels of adsorbents. Therefore, its superior adsorption ability toward VOCs, together with a high diffusion rate, makes the ordered mesoporous carbon a promising potential adsorbent for VOC disposal. PMID:25872710

  13. Features of the adsorption of naproxen enantiomers on weak chiral anion-exchangers in nonlinear chromatography

    SciTech Connect

    Asnin, Leonid; Kaczmarski, Krzysztof; Guiochon, Georges A

    2008-01-01

    The retention mechanism of the enantiomers of naproxen on a Pirkle-type chiral stationary phase (CSP) was studied. This CSP is made of a porous silica grafted with quinidine carbamate. It can interact with the weak organic electrolyte naproxen either by adsorbing it or by ion-exchange. Using frontal chromatography, we explored the adsorption equilibrium under such experimental conditions that naproxen dissociates or cannot dissociate. Under conditions preventing ionic dissociation, the adsorption isotherms were measured, the adsorption energy distributions determined, and the chromatographic profiles calculated. Three different types of the adsorption sites were found for both enantiomers. The density and the binding energy of these sites depend on the nature of the organic modifier. Different solute species, anions, neutral molecules, solvent-ion associates, and solute dimers can coexist in solution, giving rise to different forms of adsorption. This study showed the unexpected occurrence of secondary steps in the breakthrough profiles of S-naproxen in the adsorption mode at high concentrations. Being enantioselective, this phenomenon was assumed to result from the association of solute molecules involving a chiral selector moiety. A multisite Langmuir adsorption model was used to calculate band profiles. Although this model accounts excellently for the experimental adsorption isotherms, it does not explain all the features of the breakthrough profiles. A comparison between the calculated and experimental profiles allowed useful conclusions concerning the effects of the adsorbate-adsorbate and adsorbate-solvent interactions on the adsorption mechanism.

  14. Effect of effluent organic matter on the adsorption of perfluorinated compounds onto activated carbon.

    PubMed

    Yu, Jing; Lv, Lu; Lan, Pei; Zhang, Shujuan; Pan, Bingcai; Zhang, Weiming

    2012-07-30

    Effect of effluent organic matter (EfOM) on the adsorption of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) onto powdered activated carbon (PAC) was quantitatively investigated at environmentally relevant concentration levels. The adsorption of both perfluorinated compounds (PFCs) onto PAC followed pseudo-second order kinetics and fitted the Freundlich model well under the given conditions. Intraparticle diffusion was found to be the rate-controlling step in the PFC adsorption process onto PAC in the absence and presence of EfOM. The presence of EfOM, either in PFC-EfOM simultaneous adsorption onto fresh PAC or in PFC adsorption onto EfOM-preloaded PAC, significantly reduced the adsorption capacities and sorption rates of PFCs. The pH of zero point of charge was found to be 7.5 for fresh PAC and 4.2 for EfOM-preloaded PAC, suggesting that the adsorbed EfOM imparted a negative charge on PAC surface. The effect of molecular weight distribution of EfOM on the adsorption of PFCs was investigated with two EfOM fractions obtained by ultrafiltration. The low-molecular-weight compounds (<1kDa) were found to be the major contributors to the significant reduction in PFC adsorption capacity, while large-molecular-weight compounds (>30kDa) had much less effect on PFC adsorption capacity. PMID:22609392

  15. Investigation of the problems with using gas adsorption to probe catalyst pore structure evolution during coking.

    PubMed

    Gopinathan, Navin; Greaves, Malcolm; Wood, Joseph; Rigby, Sean P

    2013-03-01

    A common approach to try to understand the mechanism of coking in heterogeneous catalysts is to monitor the evolution of the pore structure using gas adsorption analysis of discharged pellets. However, the standard methods of analysis of gas adsorption data, to obtain pore-size distributions, make the key assumption of thermodynamically-independent pores. This assumption neglects the possibility of co-operative adsorption phenomena, which will shown to be a critical problem when looking at coking catalysts. In this work the serial adsorption technique has been used to detect and assess the extent of co-operative effects in adsorption within coking catalysts. The reaction of decane over a hydroprocessing catalyst was used as a case study. It has been shown that the conventional analysis method would lead to a flawed picture of the pore structure changes during the coking process. For the case-study considered in this work, it was found that co-operative adsorption effects meant that 26% of the measured adsorption was occurring in pores up to three times larger than the size conventional analysis would presume. The serial adsorption technique was thus shown to provide important additional information on pore structure evolution during coking. A study of the kinetics of adsorption has been used to infer information about the general spatial location of the coking process within a pellet. PMID:23141698

  16. Adsorption characteristics of rocks from vapor-dominated geothermal reservoir at the Geysers, CA

    SciTech Connect

    Satik, Cengiz; Walters, Mark; Horne, Roland N.

    1996-01-24

    This paper reports on a continuing experimental effort to characterize the adsorption behavior of rocks from The Geysers steam field in California. We show adsorption results obtained for 36 rock samples. All of the adsorption isotherms plotted on the same graph exhibit an envelope of isotherms. The minimum and the maximum values of the slope (or rate of adsorption) and of the magnitude within this envelope of isotherms belonged to the UOC-1 (felsite) and NCPA B-5 (serpentine) samples. The values of surface area and porosity, and pore size distribution for 19 of the samples indicated a very weak correlation with adsorption. An interpretation of the pore size distributions and the liquid saturation isotherms suggests that the change in the slope and the magnitude of the adsorption isotherms within the envelope is controlled primarily by the physical adsorption mechanism instead of capillary condensation. Grain-size and framework grain to matrix ratio are found to be insufficient to characterize this adsorption behavior. An accurate identification of the mineralogy of the samples will be essential to complete this analysis.

  17. High temperature water adsorption on The Geysers rocks

    SciTech Connect

    Gruszkiewicz, M.S.; Horita, J.; Simonson, J.M.; Mesmer, R.E.

    1997-08-01

    In order to measure water retention by geothermal reservoir rocks at the actual reservoir temperature, the ORNL high temperature isopiestic apparatus was adapted for adsorption measurements. The quality of water retained by rock samples taken from three different wells of The Geysers geothermal reservoir was measured at 150{sup degree}C, 200{sup degree}C, and 250{sup degree}C as a function of pressure in the range 0.00 {<=}p/p{sub degree} {<=} 0.98, where p{sub degree} is the saturated water vapor pressure. Both adsorption (increasing pressure) and desorption (decreasing pressure) runs were made in order to investigate the nature and the extent of the hysteresis. Additionally, low temperature gas adsorption analyses were performed on the same rock samples. Nitrogen or krypton adsorption and desorption isotherms at 77 K were used to obtain BET specific surface areas, pore volumes and their distributions with respect to pore sizes. Mercury intrusion porosimetry was also used to obtain similar information extending to very large pores (macropores). A correlation is sought between water adsorption, the surface properties, and the mineralogical and petrological characteristics of the solids.

  18. Host receptors for bacteriophage adsorption.

    PubMed

    Bertozzi Silva, Juliano; Storms, Zachary; Sauvageau, Dominic

    2016-02-01

    The adsorption of bacteriophages (phages) onto host cells is, in all but a few rare cases, a sine qua non condition for the onset of the infection process. Understanding the mechanisms involved and the factors affecting it is, thus, crucial for the investigation of host-phage interactions. This review provides a survey of the phage host receptors involved in recognition and adsorption and their interactions during attachment. Comprehension of the whole infection process, starting with the adsorption step, can enable and accelerate our understanding of phage ecology and the development of phage-based technologies. To assist in this effort, we have established an open-access resource--the Phage Receptor Database (PhReD)--to serve as a repository for information on known and newly identified phage receptors. PMID:26755501

  19. Adsorption of binary gas mixtures in heterogeneous carbon predicted by density functional theory: on the formation of adsorption azeotropes.

    PubMed

    Ritter, James A; Pan, Huanhua; Balbuena, Perla B

    2010-09-01

    Classical density functional theory (DFT) was used to predict the adsorption of nine different binary gas mixtures in a heterogeneous BPL activated carbon with a known pore size distribution (PSD) and in single, homogeneous, slit-shaped carbon pores of different sizes. By comparing the heterogeneous results with those obtained from the ideal adsorbed solution theory and with those obtained in the homogeneous carbon, it was determined that adsorption nonideality and adsorption azeotropes are caused by the coupled effects of differences in the molecular size of the components in a gas mixture and only slight differences in the pore sizes of a heterogeneous adsorbent. For many binary gas mixtures, selectivity was found to be a strong function of pore size. As the width of a homogeneous pore increases slightly, the selectivity for two different sized adsorbates may change from being greater than unity to less than unity. This change in selectivity can be accompanied by the formation of an adsorption azeotrope when this same binary mixture is adsorbed in a heterogeneous adsorbent with a PSD, like in BPL activated carbon. These results also showed that the selectivity exhibited by a heterogeneous adsorbent can be dominated by a small number of pores that are very selective toward one of the components in the gas mixture, leading to adsorption azeotrope formation in extreme cases. PMID:20712330

  20. Adsorption on a stepped substrate

    NASA Astrophysics Data System (ADS)

    Merikoski, J.; Timonen, J.; Kaski, K.

    1994-09-01

    The effect of substrate steps on the adsorption of particles is considered. The problem is formulated as a lattice-gas model with nearest neighbor interactions and it is studied by a numerical transfer-matrix method. In particular, the influence of the substrate-induced row potential on adsorbed monolayers is discussed. It is found that strong row-transition-like features appear in the presence of a row potential and it is suggested that these may be seen in adsorption on vicinal faces.

  1. Liquid-Phase Adsorption of Phenol onto Activated Carbons Prepared with Different Activation Levels.

    PubMed

    Hsieh; Teng

    2000-10-01

    The influence of the pore size distribution of activated carbon on the adsorption of phenol from aqueous solutions was explored. Activated carbons with different porous structures were prepared by gasifying a bituminous coal char to different extents of burn-off. The results of adsorption experiments show that the phenol capacity of these carbons does not proportionally increase with their BET surface area. This reflects the heterogeneity of the carbon surface for adsorption. The pore size distributions of these carbons, determined according to the Dubinin-Stoeckli equation, were found to vary with the burn-off level. By incorporating the distribution with the Dubinin-Radushkevich equation using an inverse proportionality between the micropore size and the adsorption energy, the isotherms for the adsorption of phenol onto these carbons can be well predicted. The present study has demonstrated that the heterogeneity of carbon surface for the phenol adsorption can be attributed to the different energies required for adsorption in different-size micropores. Copyright 2000 Academic Press. PMID:10998301

  2. Adipose tissue distribution and risk of metabolic disease: does thiazolidinedione-induced adipose tissue redistribution provide a clue to the answer?

    PubMed

    Yang, X; Smith, U

    2007-06-01

    The relative effect of visceral and subcutaneous obesity on the risk of chronic metabolic disease has been a matter of long-term dispute. While ample data support either of the fat depots being causative or associative, valid argument for one depot often automatically belittles the other. Paradigms such as the visceral/portal hypothesis and the acquired lipodystrophy/ectopic fat storage and endocrine hypothesis have been proposed. Nevertheless, neither hypothesis alone explains the entire pathophysiological setting. Treatment of diabetes with thiazolidinediones selectively increases fat partitioning to the subcutaneous adipose depot but does not change visceral fat accumulation. This is in contrast to the preferential visceral fat mobilisation by diet and exercise. Surgical removal of visceral or subcutaneous adipose tissue yields relatively long-lasting metabolic improvement only when combined with procedures that ameliorate adipose tissue cell composition. These studies illustrate that human adipose tissue in different anatomic locations does not work in isolation, and that there is a best-fit relationship in terms of volume and function among different fat depots that needs to be met to maintain the systemic energy balance and to prevent the complications related to obesity. PMID:17393135

  3. Surface modification of activated carbon for enhanced adsorption of perfluoroalkyl acids from aqueous solutions.

    PubMed

    Zhi, Yue; Liu, Jinxia

    2016-02-01

    The objective of the research was to examine the effect of increasing carbon surface basicity on uptake of perfluorooctane sulfonic (PFOS) and carboxylic acids (PFOA) by activated carbon. Granular activated carbons made from coal, coconut shell, wood, and phenolic-polymer-based activated carbon fibers were modified through high-temperature and ammonia gas treatments to facilitate systematical evaluation of the impact of basicity of different origins. Comparison of adsorption isotherms and adsorption distribution coefficients showed that the ammonia gas treatment was more effective than the high-temperature treatment in enhancing surface basicity. The resultant higher point of zero charges and total basicity (measured by total HCl uptake) correlated with improved adsorption affinity for PFOS and PFOA. The effectiveness of surface modification to enhance adsorption varied with carbon raw material. Wood-based carbons and activated carbon fibers showed enhancement by one to three orders of magnitudes while other materials could experience reduction in adsorption towards either PFOS or PFOA. PMID:26469934

  4. Thermodynamic formalism of water uptakes on solid porous adsorbents for adsorption cooling applications

    SciTech Connect

    Sun, Baichuan; Chakraborty, Anutosh

    2014-05-19

    This Letter presents a thermodynamic formulation to calculate the amount of water vapor uptakes on various adsorbents such as zeolites, metal organic frameworks, and silica gel for the development of an advanced adsorption chiller. This formalism is developed from the rigor of the partition distribution function of each water vapor adsorptive site on adsorbents and the condensation approximation of adsorptive water molecules and is validated with experimental data. An interesting and useful finding has been established that the proposed model is thermodynamically connected with the pore structures of adsorbent materials, and the water vapor uptake highly depends on the isosteric heat of adsorption at zero surface coverage and the adsorptive sites of the adsorbent materials. Employing the proposed model, the thermodynamic trends of water vapor uptakes on various adsorbents can be estimated.

  5. Metabolic Syndrome

    MedlinePlus

    ... cause of metabolic syndrome. The cause might be insulin resistance. Insulin is a hormone your body produces to help ... into energy for your body. If you are insulin resistant, too much sugar builds up in your ...

  6. Metabolic Myopathies

    MedlinePlus

    ... muscles. Metabolic refers to chemical reactions that provide energy, nutrients and substances necessary for health and growth. ... occur when muscle cells don’t get enough energy. Without enough energy, the muscle lacks enough fuel ...

  7. Metabolic Syndrome

    MedlinePlus

    ... is not known but genetic factors, too much body fat (especially in the waist area, the most dangerous ... Metabolic Risk Factors Measurement Large amount of abdominal body fat Waist measurement of more than 40 inches (101 ...

  8. CONTAMINANT ADSORPTION AND OXIDATION VIA FENTON REACTION

    EPA Science Inventory

    A ground water treatment process is proposed involving two cgemical processes: adsorption and oxidation. Adsorption of an organic compound onto granulated activated carbon (GAC) containing iron conveniently results in immobilizing and concentrating contaminants from the ground w...

  9. Adsorption of Organics from Domestic Water Supplies.

    ERIC Educational Resources Information Center

    McGuire, Michael J.; Suffet, Irwin H.

    1978-01-01

    This article discusses the current state of the art of organics removal by adsorption. Various theoretical explanations of the adsorption process are given, along with practical results from laboratory, pilot-scale, and full-scale applications. (CS)

  10. Influence of crystallite size of nanophased hydroxyapatite on fibronectin and osteonectin adsorption and on MC3T3-E1 osteoblast adhesion and morphology.

    PubMed

    Ribeiro, N; Sousa, S R; Monteiro, F J

    2010-11-15

    The characteristic topographical features (crystallite dimensions, surface morphology and roughness) of bioceramics may influence the adsorption of proteins relevant to bone regeneration. This work aims at analyzing the influence of two distinct nanophased hydroxyapatite (HA) ceramics, HA725 and HA1000 on fibronectin (FN) and osteonectin (ON) adsorption and MC3T3-E1 osteoblast adhesion and morphology. Both substrates were obtained using the same hydroxyapatite nanocrystals aggregates and applying the sintering temperatures of 725°C and 1000°C, respectively. The two proteins used in this work, FN as an adhesive glycoprotein and ON as a counter-adhesive protein, are known to be involved in the early stages of osteogenesis (cell adhesion, mobility and proliferation). The properties of the nanoHA substrates had an important role in the adsorption behavior of the two studied proteins and clearly affected the MC3T3-E1 morphology, distribution and metabolic activity. HA1000 surfaces presenting slightly larger grain size, higher root-mean-square roughness (Rq), lower surface area and porosity, allowed for higher amounts of both proteins adsorbed. These substrates also revealed increased number of exposed FN cell-binding domains as well as higher affinity for osteonectin. Regarding the osteoblast adhesion results, improved viability and cell number were found for HA1000 surfaces as compared to HA725 ones, independently of the presence or type of adsorbed protein. Therefore the osteoblast adhesion and metabolic activity seemed to be more sensitive to surfaces morphology and roughness than to the type of adsorbed proteins. PMID:20810127

  11. A Human Hepatocyte-Bearing Mouse: An Animal Model to Predict Drug Metabolism and Effectiveness in Humans

    PubMed Central

    Yoshizato, Katsutoshi; Tateno, Chise

    2009-01-01

    Preclinical studies to predict the efficacy and safety of drugs have conventionally been conducted almost exclusively in mice and rats as rodents, despite the differences in drug metabolism between humans and rodents. Furthermore, human (h) viruses such as hepatitis viruses do not infect the rodent liver. A mouse bearing a liver in which the hepatocytes have been largely repopulated with h-hepatocytes would overcome some of these disadvantages. We have established a practical, efficient, and large-scale production system for such mice. Accumulated evidence has demonstrated that these hepatocyte-humanized mice are a useful and reliable animal model, exhibiting h-type responses in a series of in vivo drug processing (adsorption, distribution, metabolism, excretion) experiments and in the infection and propagation of hepatic viruses. In this review, we present the current status of studies on chimeric mice and describe their usefulness in the study of peroxisome proliferator-activated receptors. PMID:19884982

  12. Surface-adsorption-induced polymer translocation through a nanopore: Effects of the adsorption strength and the surface corrugation

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaoyu; Yu, Wancheng; Luo, Kaifu

    2015-08-01

    The surface corrugation plays an important role in single polymer diffusion on attractive surfaces. However, its effect on dynamics of surface adsorption-induced polymer translocation through a nanopore is not clear. Using three-dimensional Langevin dynamics simulations, we investigate the dynamics of a flexible polymer chain translocation through a nanopore induced by the selective adsorption of translocated segments onto the trans side of the membrane. The translocation probability Pt r a n s increases monotonically, while the mean translocation time τ has a minimum as a function of the adsorption strength ɛ , which are explained from the perspective of the effective driving force for the translocation. With the surface being smoother, τ as well as the scaling exponent α of τ with the chain length N decreases. Finally, we show that the distributions of the translocation time are non-Gaussian even for strong adsorption at a moderate surface corrugation. A nearly Gaussian distribution of the translocation time is observed only for the smoothest surface we studied.

  13. Adsorption and excess fission xenon

    NASA Technical Reports Server (NTRS)

    Podosek, F. A.; Bernatowicz, T. J.; Kramer, F. E.

    1982-01-01

    The adsorption of Xe and Kr on lunar soil 10084 was measured by a method that employs only very low fractions of monolayer coverage. Results are presented as parameters for calculation of the Henry constant for adsorption as a function of temperature. The adsorption potentials are about 3 kcal/mole for Kr and 5 kcal/mole for Xe; heating the sample in vacuum increased the Xe potential to nearly 7 kcal/mole. Henry constants at the characteristic lunar temperature are about 0.3 cu cm STP/g-atm. These data were applied to consider whether adsorption is important in producing the excess fission Xe effect characteristic of highland breccias. Sorption equilibrium with a transient lunar atmosphere vented fission Xe produces concentrations seven orders of magnitude lower than observed concentrations. Higher concentrations result because of the resistance of the regolith to upward diffusion of Xe. A diffusion coefficient of 0.26 sq cm/sec is estimated for this process.

  14. NO Adsorption on Pd(111)

    NASA Astrophysics Data System (ADS)

    Garda, Graciela R.; Ferullo, Ricardo M.; Castellani, Norberto J.

    The reactive behavior of NO on Pd(111) has been studied using a semiempirical theoretical method. The adsorption sites and the related electronic structure have been considered. In particular, the dissociation process has been studied and compared with CO. Different dissociation mechanisms have been proposed and the formation of NCO species has been considered. The results follow the trends reported in the experimental literature.

  15. ADSORPTIVE MEDIA TECHNOLOGIES: MEDIA SELECTION

    EPA Science Inventory

    The presentation provides information on six items to be considered when selecting an adsorptive media for removing arsenic from drinking water; performance, EBCT, pre-treatment, regeneration, residuals, and cost. Each item is discussed in general and data and photographs from th...

  16. Protein Adsorption in Microengraving Immunoassays

    PubMed Central

    Song, Qing

    2015-01-01

    Microengraving is a novel immunoassay forcharacterizing multiple protein secretions from single cells. During the immunoassay, characteristic diffusion and kinetic time scales τD and τK determine the time for molecular diffusion of proteins secreted from the activated single lymphocytes and subsequent binding onto the glass slide surface respectively. Our results demonstrate that molecular diffusion plays important roles in the early stage of protein adsorption dynamics which shifts to a kinetic controlled mechanism in the later stage. Similar dynamic pathways are observed for protein adsorption with significantly fast rates and rapid shifts in transport mechanisms when C0* is increased a hundred times from 0.313 to 31.3. Theoretical adsorption isotherms follow the trend of experimentally obtained data. Adsorption isotherms indicate that amount of proteins secreted from individual cells and subsequently captured on a clean glass slide surface increases monotonically with time. Our study directly validates that protein secretion rates can be quantified by the microengraving immunoassay. This will enable us to apply microengraving immunoassays to quantify secretion rates from 104–105 single cells in parallel, screen antigen-specific cells with the highest secretion rate for clonal expansion and quantitatively reveal cellular heterogeneity within a small cell sample. PMID:26501282

  17. ADSORPTION OF SURFACTANT ON CLAYS

    EPA Science Inventory

    Surfactants used to enhance remediation of soils by soil washing are often lost in the process. Neither the amount nor the cause of this loss is known. It is assumed that clays present in the soil are responsible for the loss of the surfactant. In this papere, adsorption prope...

  18. ARSENIC REMOVAL USING ADSORPTION TECHNOLOGIES

    EPA Science Inventory

    The recently promulgated Arsenic Rule will require that many new drinking water systems treat their water to remove arsenic. Many groundwaters that have arsenic in their source water will likely consider adsorption technology as a reasonable approach to remove arsenic. Adsorptio...

  19. ADSORPTION TECHNOLOGIES FOR ARSENIC REMOVAL

    EPA Science Inventory

    The recently promulgated Arsenic Rule will require that many new drinking water systems treat their water to remove arsenic. Many groundwaters that have arsenic in their source water will likely consider adsorption technology as a reasonable approach to remove arsenic. Adsorptio...

  20. Development of an Extensible Computational Framework for Centralized Storage and Distributed Curation and Analysis of Genomic Data Genome-scale Metabolic Models

    SciTech Connect

    Stevens, Rick

    2010-08-01

    The DOE funded KBase project of the Stevens group at the University of Chicago was focused on four high-level goals: (i) improve extensibility, accessibility, and scalability of the SEED framework for genome annotation, curation, and analysis; (ii) extend the SEED infrastructure to support transcription regulatory network reconstructions (2.1), metabolic model reconstruction and analysis (2.2), assertions linked to data (2.3), eukaryotic annotation (2.4), and growth phenotype prediction (2.5); (iii) develop a web-API for programmatic remote access to SEED data and services; and (iv) application of all tools to bioenergy-related genomes and organisms. In response to these goals, we enhanced and improved the ModelSEED resource within the SEED to enable new modeling analyses, including improved model reconstruction and phenotype simulation. We also constructed a new website and web-API for the ModelSEED. Further, we constructed a comprehensive web-API for the SEED as a whole. We also made significant strides in building infrastructure in the SEED to support the reconstruction of transcriptional regulatory networks by developing a pipeline to identify sets of consistently expressed genes based on gene expression data. We applied this pipeline to 29 organisms, computing regulons which were subsequently stored in the SEED database and made available on the SEED website (http://pubseed.theseed.org). We developed a new pipeline and database for the use of kmers, or short 8-residue oligomer sequences, to annotate genomes at high speed. Finally, we developed the PlantSEED, or a new pipeline for annotating primary metabolism in plant genomes. All of the work performed within this project formed the early building blocks for the current DOE Knowledgebase system, and the kmer annotation pipeline, plant annotation pipeline, and modeling tools are all still in use in KBase today.

  1. 2-/sup 14/C-1-Allyl-3,5-diethyl-6-chlorouracil I: Synthesis, absorption in human skin, excretion, distribution, and metabolism in rats and rabbits

    SciTech Connect

    Kaul, R.; Hempel, B.; Kiefer, G.

    1982-08-01

    With /sup 14/C-potassium cyanate as the starting material, 2-/sup 14/C-1-allyl-3,5-diethyl-6-chlorouracil was synthesized for in vitro and in vivo absorption studies in human skin and for metabolic studies in rats and rabbits. The radioactivity in the horny layer, epidermis, and dermis of the human skin was determined after different intervals of time, and the radioactivity excreted in the urine was measured by collecting samples for 5 days from a patient and also under occlusion conditions. Almost 90% of the radioactivity remained on the surface and approximately 6.28% penetrated and was systemically absorbed. Over a 5-day period, a total of 3.25% was excreted. Almost 3% was systemically absorbed and cumulated in the system. After intraperitoneal application in male and female rats, most of the radioactivity was excreted in the feces and urine, with female rats excreting more in the urine than male rats. The radioactivity rose in the organs in the first 3 hr and then decreased. At the end of 144 hr, no appreciable radioactivity could be found in the organs and tissues, except in the carcass where the cumulation was maximum (1%). After intravenous injection in rabbits, most of the radioactivity (80%) was excreted in the urine and only 4% in the feces. At the end of 96 hr, approximately 3% was cumulated in the body. The drug was quantitatively metabolized in both rats and rabbits: Metabolite 1 (70-85%), Metabolite 2 (10-15%), Metabolite 3 (5-10%), and Metabolite 4 (0.3%).

  2. Thermodynamic investigation of trichloroethylene adsorption in water-saturated microporous adsorbents

    SciTech Connect

    Farrell, J.; Hauck, B.; Jones, M.

    1999-08-01

    Adsorption of trichloroethylene (TCE) in adsorbents containing hydrophilic and hydrophobic micropores was investigated in order to determine the mechanisms responsible for TCE adsorption on mineral solids. A high-pressure liquid chromatography method was used to measure TCE adsorption isotherms on three microporous adsorbents. Silica gel and zeolite type NaX were used as hydrophilic model adsorbents, and hexamethyldisilazane (HMDS)-treated silica gel was used as a model hydrophobic adsorbent. Batch uptake and desorption isotherms were also measured on the hydrophilic silica gel. Uptake of TCE by all three adsorbents was linear over the concentration range investigated. However, the silica gel desorption isotherm was highly nonlinear, as indicated by its Freundlich isotherm exponent of 0.58. Capillary phase separation into hydrophobic micropores was postulated as being responsible for the isotherm hysteresis. Supporting this hypothesis was the conformance of the TCE adsorption isotherm to Dubinin-Radushkevitch volume filling of micropores theory. The enthalpies for TCE adsorption on all three solids were determined by van't Hoff analysis of distribution coefficients measured over a temperature range from 5 to 90 C. The TCE adsorption enthalpies on the silica gel and HMDS silica gel were exothermic, but on the zeolite adsorption was endothermic. High exothermic adsorption enthalpies on the silica gel adsorbents indicated that TCE adsorption was occurring in hydrophobic micropores, and that adsorption on surfaces with large radii of curvature contributed only minimally to the total uptake. This indicates that the predominant mechanism for TCE adsorption on these mineral solids is not partitioning into the vicinal water layer.

  3. Removal of Arsenic from Drinking Water by Adsorption and Coagulation

    NASA Astrophysics Data System (ADS)

    Zhang, M.; Sugita, H.; Hara, J.; Takahashi, S.

    2013-12-01

    Removal of arsenic from drinking water has been an important issue worldwide, which has attracted greater attentions in recent years especially for supplying safe drinking water in developing countries. Although many kinds of treatment approaches that are available or applicable both in principle and practice, such as adsorption, coagulation, membrane filtration, ion exchange, biological process, electrocoagulation and so on, the first 2 approaches (i.e., adsorption and coagulation) are most promising due to the low-cost, high-efficiency, simplicity of treating systems, and thus can be practically used in developing countries. In this study, a literature survey on water quality in Bangladesh was performed to understand the ranges of arsenic concentration and pH of groundwater in Bangladesh. A series of tests were then organized and performed to investigate the effects of arsenic concentration, arsenic forms, pH, chemical compositions of the materials used for adsorption and coagulation, particle size distribution and treatment time on quality of treated water. The experimental results obtained in the study illustrated that both adsorption and coagulation can be used to effectively reduce the concentrations of either arsenic (V) or arsenic (III) from the contaminated water. Coagulation of arsenic with a magnesium-based material developed in this study can be very effective to remove arsenic, especially arsenic (V), from contaminated water with a concentration of 10 ppm to an undetectable level of 0.002 ppm by ICP analyses. Compared to arsenic (III), arsenic (V) is easier to be removed. The materials used for adsorption and coagulation in this study can remove arsenic (V) up to 9 mg/g and 6 mg/g, and arsenic (III) up to 4 mg/g and 3 mg/g, respectively, depending on test conditions and compositions of the materials being used. The control of pH during treatment can be a challenging technical issue for developing both adsorbent and coagulant. Keywords: Water Treatment

  4. Adsorption of fulvic acid on goethite

    SciTech Connect

    Filius, J.D.; Lumsdon, D.G.; Meeussen, J.C.L.; Hiemstra, T.; Riemsduk, W.H. van

    2000-01-01

    The adsorption of fulvic acid by goethite was determined experimentally as a function of concentration, pH, and ionic strength. The data were described with the CD-MUSIC model of Hiemstra and Van Riemsdijk (1996), which allows the distribution of charge of the bound fulvate molecule over a surface region. Simultaneously, the concentration, pH, and salt dependency of the binding of fulvic acid can be described. Using the same parameters, the basic charging behavior of the goethite in the absence of fulvic acid could be described well. The surface species used in the model indicate that inner sphere coordination of carboxylic groups of the fulvate molecule is important at low pH, whereas at high pH the outer sphere coordination with reactive groups of the fulvate molecule with high proton affinity is important.

  5. Adsorption of SO2 on bituminous coal char and activated carbon fiber

    USGS Publications Warehouse

    DeBarr, J.A.; Lizzio, A.A.; Daley, M.A.

    1997-01-01

    The SO2 adsorption behaviors of activated carbons produced from Illinois coal and of commercially prepared activated carbon fibers (ACFs) were compared. There was no relation between surface area of coal-based carbons and SO2 adsorption, whereas adsorption of SO2 on the series of ACFs was inversely proportional to N2 BET surface area. Higher surface area ACFs had wider pores and adsorbed less SO2; thus, pore size distribution is thought to play a significant role in SO2 adsorption for these materials. Oxidation with HNO3 and/or H2SO4, followed by heat treatment at 700-925 ??C to remove carbon-oxygen complexes, resulted in increased SO2 adsorption for both coal chars and ACFs. This behavior was explained by an increase in the available number of free sites, previously occupied by oxygen and now available for SO2 adsorption. The use of nitrogen-containing functional groups on ACFs of proper pore size shows promise for further increasing SO2 adsorption capacities. Knowledge of the relationship among the number of free sites, pore size, and surface chemistry on corresponding SO2 adsorption should lead to the development of more efficient adsorbents prepared from either coal or ACFs.

  6. KAE609 (Cipargamin), a New Spiroindolone Agent for the Treatment of Malaria: Evaluation of the Absorption, Distribution, Metabolism, and Excretion of a Single Oral 300-mg Dose of [14C]KAE609 in Healthy Male Subjects.

    PubMed

    Huskey, Su-Er W; Zhu, Chun-Qi; Fredenhagen, Andreas; Kühnöl, Jürgen; Luneau, Alexandre; Jian, Zhigang; Yang, Ziping; Miao, Zhuang; Yang, Fan; Jain, Jay P; Sunkara, Gangadhar; Mangold, James B; Stein, Daniel S

    2016-05-01

    KAE609 [(1'R,3'S)-5,7'-dichloro-6'-fluoro-3'-methyl-2',3',4',9'-tetrahydrospiro[indoline-3,1'-pyridol[3,4-b]indol]-2-one] is a potent, fast-acting, schizonticidal agent in clinical development for the treatment of malaria. This study investigated the absorption, distribution, metabolism, and excretion of KAE609 after oral administration of [(14)C]KAE609 in healthy subjects. After oral administration to human subjects, KAE609 was the major radioactive component (approximately 76% of the total radioactivity in plasma); M23 was the major circulating oxidative metabolite (approximately 12% of the total radioactivity in plasma). Several minor oxidative metabolites (M14, M16, M18, and M23.5B) were also identified, each accounting for approximately 3%-8% of the total radioactivity in plasma. KAE609 was well absorbed and extensively metabolized, such that KAE609 accounted for approximately 32% of the dose in feces. The elimination of KAE609 and metabolites was primarily mediated via biliary pathways. M23 was the major metabolite in feces. Subjects reported semen discoloration after dosing in prior studies; therefore, semen samples were collected once from each subject to further evaluate this clinical observation. Radioactivity excreted in semen was negligible, but the major component in semen was M23, supporting the rationale that this yellow-colored metabolite was the main source of semen discoloration. In this study, a new metabolite, M16, was identified in all biologic matrices albeit at low levels. All 19 recombinant human cytochrome P450 enzymes were capable of catalyzing the hydroxylation of M23 to form M16 even though the extent of turnover was very low. Thus, electrochemistry was used to generate a sufficient quantity of M16 for structural elucidation. Metabolic pathways of KAE609 in humans are summarized herein and M23 is the major metabolite in plasma and excreta. PMID:26921387

  7. Aberrant Expression and Distribution of Enzymes of the Urea Cycle and Other Ammonia Metabolizing Pathways in Dogs with Congenital Portosystemic Shunts

    PubMed Central

    van Straten, Giora; van Steenbeek, Frank G.; Grinwis, Guy C. M.; Favier, Robert P.; Kummeling, Anne; van Gils, Ingrid H.; Fieten, Hille; Groot Koerkamp, Marian J. A.; Holstege, Frank C. P.; Rothuizen, Jan; Spee, Bart

    2014-01-01

    The detoxification of ammonia occurs mainly through conversion of ammonia to urea in the liver via the urea cycle and glutamine synthesis. Congenital portosystemic shunts (CPSS) in dogs cause hyperammonemia eventually leading to hepatic encephalopathy. In this study, the gene expression of urea cycle enzymes (carbamoylphosphate synthetase (CPS1), ornithine carbamoyltransferase (OTC), argininosuccinate synthetase (ASS1), argininosuccinate lyase (ASL), and arginase (ARG1)), N-acetylglutamate synthase (NAGS), Glutamate dehydrogenase (GLUD1), and glutamate-ammonia ligase (GLUL) was evaluated in dogs with CPSS before and after surgical closure of the shunt. Additionally, immunohistochemistry was performed on urea cycle enzymes and GLUL on liver samples of healthy dogs and dogs with CPSS to investigate a possible zonal distribution of these enzymes within the liver lobule and to investigate possible differences in distribution in dogs with CPSS compared to healthy dogs. Furthermore, the effect of increasing ammonia concentrations on the expression of the urea cycle enzymes was investigated in primary hepatocytes in vitro. Gene-expression of CPS1, OTC, ASL, GLUD1 and NAGS was down regulated in dogs with CPSS and did not normalize after surgical closure of the shunt. In all dogs GLUL distribution was localized pericentrally. CPS1, OTC and ASS1 were localized periportally in healthy dogs, whereas in CPSS dogs, these enzymes lacked a clear zonal distribution. In primary hepatocytes higher ammonia concentrations induced mRNA levels of CPS1. We hypothesize that the reduction in expression of urea cycle enzymes, NAGS and GLUD1 as well as the alterations in zonal distribution in dogs with CPSS may be caused by a developmental arrest of these enzymes during the embryonic or early postnatal phase. PMID:24945279

  8. Copepods in ice-covered seas—Distribution, adaptations to seasonally limited food, metabolism, growth patterns and life cycle strategies in polar seas

    NASA Astrophysics Data System (ADS)

    Conover, R. J.; Huntley, M.

    1991-07-01

    rhythms under or near the ice have also been observed for several species. In the Northern Hemisphere larger zooplanktonic species may take two, three, or possibly more years to reach maturity, but the grand strategy, apparently used by all, is to assure that their young have reached active feeding stages by the time of maximum primary production in the water column so that maximum growth, often, but not always, with emphasis on lipid storage, can occur during the often brief, but usually intense, summer bloom. The rate of growth of arctic or antarctic zooplankton is not so important as assuring a high level of fecundity when maturity comes. Overwintering is probably not a great hardship and diapause may not be a useful strategy because the environmental temperature is constantly near the freezing point of sea water, and basal metabolism accordingly low. Nonetheless, feeding behaviour and metabolic rates have strong seasonal signals. In the absence of other stimuli, light must be involved in the transformation from winter to summer metabolism and visa versa but the mechanisms still remain obscure.

  9. [Adsorption of Cu on Core-shell Structured Magnetic Particles: Relationship Between Adsorption Performance and Surface Properties].

    PubMed

    Li, Qiu-mei; Chen, Jing; Li, Hai-ning; Zhang, Xiao-lei; Zhang, Gao-sheng

    2015-12-01

    In order to reveal the relationship between the adsorption performance of adsorbents and their compositions, structure, and surface properties, the core-shell structured Fe₃O₄/MnO2 and Fe-Mn/Mn₂2 magnetic particles were systematically characterized using multiple techniques and their Cu adsorption behaviors as well as mechanism were also investigated in details. It was found that both Fe₃O4 and Fe-Mn had spinel structure and no obvious crystalline phase change was observed after coating with MnO₂. The introduction of Mn might improve the affinity between the core and the shell, and therefore enhanced the amount and distribution uniformity of the MnO₂ coated. Consequently, Fe-Mn/MnO₂ exhibited a higher BET specific surface area and a lower isoelectric point. The results of sorption experiments showed that Fe-Mn had a higher maximal Cu adsorption capacity of 33.7 mg · g⁻¹ at pH 5.5, compared with 17.5 mg · g⁻¹ of Fe₃O4. After coating, the maximal adsorption capacity of Fe-Mn/MnO₂ was increased to 58.2 mg · g⁻¹, which was 2.6 times as high as that of Fe₃O₄/MnO₂ and outperformed the majority of magnetic adsorbents reported in literature. In addition, a specific adsorption of Cu occurred at the surface of Fe₃O₄/MnO₂ or Fe-Mn/MnO₂ through the formation of inner-sphere complexes. In conclusion, the adsorption performance of the magnetic particles was positively related to their compositions, structure, and surface properties. PMID:27011990

  10. Structure and hydrogen adsorption properties in low density nanoporous carbons from simulations

    SciTech Connect

    Peng, L.; Morris, James R

    2012-01-01

    We systematically model the hydrogen adsorption in nanoporous carbons over a wide range of carbon bulk densities (0.6 - 2.4 g/cm3) by using tight binding molecular dynamics simulations for the carbon structures and thermodynamics calculations of the hydrogen adsorption. The resulting structures are in good agreement with the experimental data of ultra-microporous carbon (UMC), a wood-based activated carbon, as indicated by comparisons of the microstructure at atomic level, pair distribution function, and pore size distribution. The hydrogen adsorption calculations in carbon structures demonstrate both a promising hydrogen storage capacity (excess uptake of 1.33 wt% at 298K and 5 MPa, for carbon structures at the lower range of densities) and a reasonable heat of adsorption (12-22 kJ/mol). This work demonstrates that increasing the heat of adsorption does not necessarily increase the hydrogen uptake. In fact, the available adsorption volume is as important as the isosteric heat of adsorption for hydrogen storage in nanoporous carbons.

  11. Distribution variation of a metabolic uncoupler, 2,6-dichlorophenol (2,6-DCP) in long-term sludge culture and their effects on sludge reduction and biological inhibition.

    PubMed

    Tian, Yu; Zhang, Jun; Wu, Di; Li, Zhipeng; Cui, Yanni

    2013-01-01

    Distribution variation of a metabolic uncoupler, 2,6-dichlorophenol (2,6-DCP), in long-term sludge culture was studied, and the effects on sludge reduction and biological inhibition of this chemical during the 90-day operation were established. The extracellular polymeric substance (EPS) matrix functioned as a protective barrier for the bacteria inside sludge flocs to 2,6-DCP, resulting in the transfer of 2,6-DCP from the liquid phase to the activated sludge fraction. Significant sludge reduction (about 40%) was observed after the addition of 2,6-DCP in the first 40 days, while the ineffective function of 2,6-DCP in sludge reduction (days 70-90) might be correlated to the EPS protection mechanism. The inhibitory effect of 2,6-DCP on the COD removal was extremely lower than on the nitrification performance due to the fact that 2,6-DCP was much more toxic to autotrophic microorganisms than heterotrophic microorganisms. Moreover, both of them recovered to a higher level again with the transfer potential of 2,6-DCP to sludge. Thus, the application of metabolic uncoupler for excess sludge reduction should be cautious. PMID:23123050

  12. Dye adsorption behavior of Luffa cylindrica fibers.

    PubMed

    Demir, H; Top, A; Balköse, D; Ulkü, S

    2008-05-01

    Using natural Luffa cylindrica fibers as adsorbent removal of methylene blue dye from aqueous solutions at different temperatures and dye concentrations was investigated in this study. Thermodynamics and kinetics of adsorption were also investigated. The adsorption isotherms could be well defined with Langmuir model instead of Freundlich model. The thermodynamic parameters of methylene blue (MB) adsorption indicated that the adsorption is exothermic and spontaneous. The average MB adsorption capacity was found out as 49 mg/g and average BET surface area of fibers was calculated as 123 m(2)/g. PMID:17919814

  13. Gas adsorption on microporous carbon thin films

    SciTech Connect

    O'Shea, S.; Pailthorpe, B.A.; Collins, R.E.; Furlong, D.N. )

    1992-05-01

    A gas adsorption study was performed on amorphous hydrogenated carbon thin films which are deposited by reactive magnetron sputtering using acetylene gas. It is found that the films are highly microporous. Annealing significantly increases the adsorption capacity of the films and decreases the effects of low-pressure hysteresis in the adsorption isotherms. The general gas adsorption behavior closely resembles that of powdered activated carbons. The Dubinin-Radushkevich equation can be used to model the submonolayer adsorption isotherm for a variety of gases. 38 refs., 9 figs., 3 tabs.

  14. Adsorption characteristics of metal ions on chitosan chemically modified by D-galactose

    SciTech Connect

    Kondo, Kazuo; Sumi, Hisaharu; Matsumoto, Michiaki

    1996-07-01

    The adsorption characteristics of metal ions on chitosan chemically modified by D-galactose were examined. The pH dependency on the distribution ratio was found to be affected by the valency of the metal ion, and the apparent adsorption equilibrium constants of the metal ions were determined. The order of adsorption of the metal ions is Ga > In > Nd > Eu for the trivalent metal ions and Cu > Ni > Co for the divalent metal ions. It is believed that amino and hydroxyl groups in the chitosan act as a chelating ligand.

  15. Deformation of Microporous Carbons during N2, Ar, and CO2 Adsorption: Insight from the Density Functional Theory.

    PubMed

    Balzer, Christian; Cimino, Richard T; Gor, Gennady Y; Neimark, Alexander V; Reichenauer, Gudrun

    2016-08-16

    Using the nonlocal density functional theory, we investigate adsorption of N2 (77 K), Ar (77 K), and CO2 (273 K) and respective adsorption-induced deformation of microporous carbons. We show that the smallest micropores comparable in size and even smaller than the nominal molecular diameter of the adsorbate contribute significantly to the development of the adsorption stress. While pores of approximately the nominal adsorbate diameter exhibit no adsorption stress regardless of their filling level, the smaller pores cause expansive adsorption stresses up to almost 4 GPa. Accounting for this effect, we determined the pore-size distribution of a synthetic microporous carbon by simultaneously fitting its experimental CO2 adsorption isotherm (273 K) and corresponding adsorption-induced strain measured by in situ dilatometry. Based on the pore-size distribution and the elastic modulus fitted from CO2 data, we predicted the sample's strain isotherms during N2 and Ar adsorption (77 K), which were found to be in reasonable agreement with respective experimental data. The comparison of calculations and experimental results suggests that adsorption-induced deformation caused by micropores is not limited to the low relative pressures typically associated with the micropore filling, but is effective over the whole relative pressure range up to saturation pressure. PMID:27420036

  16. Adsorption Behavior of Nonplanar Phthalocyanines: Competition of Different Adsorption Conformations

    PubMed Central

    2016-01-01

    Using density functional theory augmented with state-of-the-art van der Waals corrections, we studied the geometric and electronic properties of nonplanar chlorogallium-phthalocyanine GaClPc molecules adsorbed on Cu(111). Comparing these results with published experimental data for adsorption heights, we found indications for breaking of the metal–halogen bond when the molecule is heated during or after the deposition process. Interestingly, the work-function change induced by this dissociated geometry is the same as that computed for an intact adsorbate layer in the “Cl-down” configuration, with both agreeing well with the experimental photoemission data. This is unexpected, as the chemical natures of the adsorbates and the adsorption distances are markedly different in the two cases. The observation is explained as a consequence of Fermi-level pinning due to fractional charge transfer at the interface. Our results show that rationalizing the adsorption configurations on the basis of electronic interface properties alone can be ambiguous and that additional insight from dispersion-corrected DFT simulations is desirable. PMID:27066160

  17. The production and distribution of IL-6 and TNF-α in subcutaneous adipose tissue and their correlation with serum concentrations in Welsh ponies with equine metabolic syndrome

    PubMed Central

    Marycz, Krzysztof; Śmieszek, Agnieszka; Nicpoń, Jakub

    2015-01-01

    A main symptom of equine metabolic syndrome (EMS) in ponies is pathological obesity characterized by abnormal accumulation of fat deposits and inflammation. In this study, we analyzed the expression of two pro-inflammatory cytokines, interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), in subcutaneous adipose tissue and the correlation with serum concentrations in peripheral blood of Welsh ponies. Based on clinical examination findings, the animals were divided into two groups: ponies affected with EMS (n = 8) and obese ponies (n = 8). The adipose tissue was examined using immunohistochemical analysis while concentrations IL-6 and TNF-α were measured using enzyme-linked immunosorbent assays (ELISAs). Additionally, histological characterization of the adipose tissue was performed. The results obtained showed that IL-6 expression in adipose tissue biopsies derived from animals with EMS was enhanced while TNF-α levels of both groups were comparable. Compared to the obese ponies, EMS animals also had significantly elevated levels of serum IL-6 and TNF-α. Histological analysis revealed macrophage infiltration and fibrosis in adipose tissue preparations from the EMS group. These data suggest that IL-6 may play a key role in the course of EMS in Welsh ponies. Our findings also demonstrated that analysis of pro-inflammatory cytokines levels in serum may serve as an additional tool for diagnosing EMS. PMID:25269712

  18. Blood Lipid Distribution, Aortic Cholesterol Concentrations, and Selected Inflammatory and Bile Metabolism Markers in Syrian Hamsters Fed a Standard Breeding Diet

    PubMed Central

    Stephens, Amanda M; Sanders, Timothy H

    2015-01-01

    Hamsters are often used to determine the effects of various dietary ingredients on the development of cardiovascular disease (CVD). The study was conducted to obtain baseline data on CVD risk factors and mRNA expression of selected genes in hamsters fed a standard maintenance diet (STD) for 24 wk, beginning when animals were 7 wk old. Plasma triacylglycerol and aortic cholesteryl ester concentrations did not significantly change during the study. Total plasma cholesterol (75.9–127.9 mg/dL), LDL- (3.2–12.2 mg/dL), and HDL- (53.8–98.9 mg/dL) cholesterols increased over the 24wk study. Aortic total cholesterol increased from 9.72 to 12.20 μg/mg protein, whereas aortic cholesteryl ester, a measure of atherosclerosis development, was less than 0.18 μg/mg protein throughout the study. The expression of hepatic endothelin 1, peroxisome proliferator-activated receptor α , and hepatic cholesterol 7-α-hydroxylase mRNA did not change throughout the study, indicating that fatty acid β-oxidation and cholesterol metabolism remained consistent. The mRNA expression of ATP-binding cassette, subfamily B member 11 increased between wk 0 and 8 but then remained unchanged, suggesting increased requirements for cholesterol in early growth. These results indicate that the consumption of a STD does not increase atherosclerotic disease risk factors in golden Syrian hamsters through 31 wk of age. PMID:26224433

  19. Interaction of functionally bound vitamins in the distribution and metabolism of (/sup 14/C)nicotinic acid in tissues and blood cells

    SciTech Connect

    Rozanov, A.Ya.; Yakubik, E.Yu.

    1986-03-10

    Leukocytes absorb two orders of magnitude more of labeled nicotinic acid ((/sup 14/C)NA) than erythrocytes (recalculated per cell). The dynamics of the binding of the labeled vitamin by leukocytes is biphasic, with the formation chiefly of (/sup 14/C)-nicotinic coenzymes in the shortest periods after its injection into rats. At the same time, injected thiamine, riboflavin, lipoate, and pantothenate increase the accumulation of labeled metabolites of nicotinate in the blood and leukocytes of rats by a factor of 2.1 and 4.1, respectively. The metabolism of subcutaneously injected (/sup 14/C)NA occurs chiefly in the digestive system, with a pronounced biphasic dynamics of the changes in the content of labeled metabolites in the liver and small intestine, with secretion of substantial amounts of them with the digestive juices. At the same time, functionally bound vitamins introduced increase the incorporation of the total label into liver tissue (to 45% of the introduced dose, versus 33% in the control) and the rise in the content of (/sup 14/C)-pyridine nucleotides. Analogous effects were also observed in the accumulation of labeled metabolites of (/sup 14/C)NA in the membranes of the small intestine.

  20. Adsorption of lipase on polypropylene powder.

    PubMed

    Gitlesen, T; Bauer, M; Adlercreutz, P

    1997-04-01

    Adsorption of different lipases by EP-100 polypropylene powder from crude and pure lipase preparations was studied. Langmuir isotherms described the adsorption equilibria well both for protein and lipase activity adsorption. Adsorption isotherms for five different proteins all gave a similar saturation level of 220 mg protein per g carrier. Twelve commercial lipase preparations were tested for selectivity in the adsorption of lipase. For all preparations the selectivity factor was larger than one. In a crude lipase preparation from Pseudomonas fluorescence, the specific activity in solution decreased by two orders of magnitude after adsorption. The adsorption was not significantly influenced by pH changes in the adsorption buffer, indicating that hydrophobic and not electrostatic interactions are the dominating adsorption forces. Adsorption of a crude lipase from Candida rugosa (Sigma) was fast and equilibrium was reached in 30 and 100 min for protein and lipase activity adsorption respectively. Desorption in aqueous solution was negligible. Investigations with seven different lipases showed no correlation between the specific lipolytic activity of dissolved enzyme in aqueous solution and the specific activity of adsorbed enzyme in an esterification reaction in organic solvent. PMID:9106498

  1. Adsorption of organic chemicals in soils.

    PubMed Central

    Calvet, R

    1989-01-01

    This paper presents a review on adsorption of organic chemicals on soils sediments and their constituents. The first part of this review deals with adsorption from gas and liquid phases and gives a discussion on the physical meaning of the shape of adsorption isotherms. Results show that no general rules can be proposed to describe univocally the relation between the shape of isotherms and the nature of adsorbate-adsorbent system. Kinetics of adsorption is discussed through the description of various models. Theoretical developments exist both for the thermodynamics and the kinetics of adsorption, but there is a strong need for experimental results. Possible adsorption mechanisms are ion exchange, interaction with metallic cations, hydrogen bonds, charge transfers, and London-van der Waals dispersion forces/hydrophobic effect. However, direct proofs of a given mechanism are rare. Several factors influence adsorption behavior. Electronic structure of adsorbed molecules, properties of adsorbents, and characteristics of the liquid phase are discussed in relation to adsorption. Such properties as water solubility, organic carbon content of adsorbing materials, and the composition of the liquid phase are particularly important. Evaluation of adsorption can be obtained through either laboratory measurements or use of several correlations. Adsorption measurements must be interpreted, taking into account treatment of adsorbent materials, experimental conditions, and secondary phenomena such as degradations. Correlations between adsorption coefficients and water-octanol partition coefficient or water solubility are numerous. They may be useful tools for prediction purposes. Relations with transport, bioavailability, and degradation are described. PMID:2695323

  2. Phosphate adsorption on lanthanum loaded biochar.

    PubMed

    Wang, Zhanghong; Shen, Dekui; Shen, Fei; Li, Tianyu

    2016-05-01

    To attain a low-cost and high-efficient phosphate adsorbent, lanthanum (La) loaded biochar (La-BC) prepared by a chemical precipitation method was developed. La-BC and its pristine biochar (CK-BC) were comparatively characterized using zeta potential, BET surface area, scanning electron microscopy/energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). The adsorption ability and the mechanisms during adsorption process for the La-BC samples were also investigated. La loaded on the surface of biochar can be termed as La-composites (such as LaOOH, LaONO3 and La(OH)3), leading to the decrease of negative charge and surface area of biochar. La-BC exhibited the high adsorption capacity to phosphate compared to CK-BC. Adsorption isotherm and adsorption kinetic studies showed that the Langmuir isotherm and second order model could well describe the adsorption process of La-BC, indicating that the adsorption was dominated by a homogeneous and chemical process. The calculated maximum adsorption capacity was as high as 46.37 mg g(-1) (computed in P). Thermodynamic analysis revealed that the adsorption was spontaneous and endothermic. SEM, XRD, XPS and FT-IR analysis suggested that the multi-adsorption mechanisms including precipitation, ligand exchange and complexation interactions can be evidenced during the phosphate adsorption process by La-composites in La-BC. PMID:26871732

  3. Metabolic microspheres

    NASA Astrophysics Data System (ADS)

    Fox, Sidney W.

    1980-08-01

    A systematic review of catalytic activities in thermal proteinoids and microspheres aggregated therefrom yields some new inferences on the origins and evolution of metabolism. Experiments suggest that, instead of being inert, protocells were already biochemically and cytophysically competent. The emergence and refinement of metabolism ab initio is thus partly traced conceptually. When the principle of molecular self-instruction, as of amino acids in peptide synthesis, is taken into account as a concomitant of natural selection, an expanded theory of organismic evolution, including saltations, emerges.

  4. Metabolic analyzer

    NASA Technical Reports Server (NTRS)

    Lem, J. D.

    1977-01-01

    The metabolic analyzer was designed to support experiment M171. It operates on the so-called open circuit method to measure a subject's metabolic activity in terms of oxygen consumed, carbon dioxide produced, minute volume, respiratory exchange ratio, and tidal volume or vital capacity. The system operates in either of two modes. (1) In Mode I, inhaled respiratory volumes are actually measured by a piston spirometer. (2) In Mode II, inhaled volumes are calculated from the exhaled volume and the measured inhaled and exhaled nitrogen concentrations. This second mode was the prime mode for Skylab. Following is a brief description of the various subsystems and their operation.

  5. Adsorption processing - Optimization through understanding

    SciTech Connect

    Not Available

    1986-01-01

    Adsorption processes used in the natural gas industry for dehydration, sweetening and liquids recovery are batch systems, very similar to laboratory chromatographs. For continuous processing a plant must contain multiple adsorbers, so that while one column adsorbs, another or others can be desorbed and prepared for their next turn at adsorption. Variations in the cycle, the number of adsorbers and the way multiple towers may be sequenced; in series, in parallel, etc. are so numerous that an entire presentation could be devoted to the reasons and results of the various arrangements. For a consideration of the process fundamentals and the way they can be manipulated, this discussion concentrates on a simple two tower system typical of what is frequently used to dehydrate gas ahead of a cryogenic plant; a turboexpander unit or a peak shaving LNG facility.

  6. Adsorption kinetics of diatomic molecules.

    PubMed

    Burde, Jared T; Calbi, M Mercedes

    2014-05-01

    The adsorption dynamics of diatomic molecules on solid surfaces is examined by using a Kinetic Monte Carlo algorithm. Equilibration times at increasing loadings are obtained, and explained based on the elementary processes that lead to the formation of the adsorbed film. The ability of the molecules to change their orientation accelerates the overall uptake and leads to competitive kinetic behaviour between the different orientations. The dependence of the equilibration time on coverage follows the same decreasing trend obtained experimentally for ethane adsorption on closed-end carbon nanotube bundles. The exploration of molecule-molecule interaction effects on this trend provides relevant insights to understand the kinetic behaviour of other species, from simpler molecules to larger polyatomic molecules, adsorbing on surfaces with different binding strength. PMID:24654004

  7. An adsorption model of the heterogeneous nucleation of solidification

    SciTech Connect

    Kim, W.T.; Cantor, B. . Oxford Centre for Advanced Materials and Composites)

    1994-09-01

    An adsorption model has been developed to describe the heterogeneous nucleation of solidification in an A-B eutectic or monotectic alloy system. The interface between A-rich [alpha] solid and B-rich liquid is treated as a mixture of A solid, B solid, A liquid and B liquid atoms, randomly distributed as a monolayer between the two phases. The interfacial energy is calculated by summing pairwise bonding energies, and is then minimized to determine the equilibrium interface solid fraction and composition. With decreasing temperature, the interface monolayer changes sharply from liquid to solid, with a composition close to pure B. This sharp onset of interface adsorption of solid B atoms corresponds to [alpha] acting as a catalyst for the heterogeneous nucleation of B-rich [beta] solid. Adsorption close to the eutectic temperature and therefore efficient nucleation catalysis is promoted by a large difference between the melting points of A and B, and a small difference between the solid and liquid immiscibilities of A and B. Predicted undercoolings for the onset of adsorption and nucleation catalysis can be obtained directly from simple phase diagram data, and give good agreement with previous measurements in the Ag-Pb and Al-Sn alloy systems.

  8. CO₂ adsorption on amine-functionalized periodic mesoporous benzenesilicas.

    PubMed

    Sim, Kyohyun; Lee, Nakwon; Kim, Joonseok; Cho, Eun-Bum; Gunathilake, Chamila; Jaroniec, Mietek

    2015-04-01

    CO2 adsorption was investigated on amine-functionalized mesoporous silica (SBA-15) and periodic mesoporous organosilica (PMO) samples. Hexagonally (p6mm) ordered mesoporous SBA-15 and benzene-PMO (BPMO) samples were prepared in the presence of Pluronic P123 block copolymer template under acidic conditions. Three kinds of amine-containing organosilanes and polyethylenimine were used to functionalize SBA-15 and BPMO. Small-angle X-ray scattering and nitrogen adsorption isotherms showed that these samples featured ordered mesostructure, high surface area, and narrow pore size distributions. Solid-state (13)C- and (29)Si cross-polarization magic-angle spinning NMR spectra showed chemical linkage between amine-containing modifiers and the surface of mesoporous materials. The chemically linked amine-containing modifiers were found to be on both the inner and outer surfaces. N-[3-(trimethoxysilyl)propyl]ethylenediamine-modified BPMO (A2-BPMO) sample exhibited the highest CO2 uptake (i.e., ∼3.03 mmol/g measured on a volumetric adsorption analyzer) and the fastest adsorption rate (i.e., ∼13 min to attain 90% of the maximum amount) among all the samples studied. Selectivity and reproducibility measurements for the A2-BPMO sample showed quite good performance in flowing N2 gas at 40 mL/min and CO2 gas of 60 mL/min at 25 °C. PMID:25742049

  9. Adsorption of comb copolymers on weakly attractive solid surfaces.

    PubMed

    Striolo, A; Jayaraman, A; Genzer, J; Hall, C K

    2005-08-01

    In this work continuum and lattice Monte Carlo simulation methods are used to study the adsorption of linear and comb polymers on flat surfaces. Selected polymer segments, located at the tips of the side chains in comb polymers or equally spaced along the linear polymers, are attracted to each other and to the surface via square-well potentials. The rest of the polymer segments are modeled as tangent hard spheres in the continuum model and as self-avoiding random walks in the lattice model. Results are presented in terms of segment-density profiles, distribution functions, and radii of gyration of the adsorbed polymers. At infinite dilution the presence of short side chains promotes the adsorption of polymers favoring both a decrease in the depletion-layer thickness and a spreading of the polymer molecule on the surface. The presence of long side chains favors the adsorption of polymers on the surface, but does not permit the spreading of the polymers. At finite concentration linear polymers and comb polymers with long side chains readily adsorb on the solid surface, while comb polymers with short side chains are unlikely to adsorb. The simple models of comb copolymers with short side chains used here show properties similar to those of associating polymers and of globular proteins in aqueous solutions, and can be used as a first approximation to investigate the mechanism of adsorption of proteins onto hydrophobic surfaces. PMID:16122338

  10. Studies on Vapor Adsorption Systems

    NASA Technical Reports Server (NTRS)

    Shamsundar, N.; Ramotowski, M.

    1998-01-01

    The project consisted of performing experiments on single and dual bed vapor adsorption systems, thermodynamic cycle optimization, and thermal modeling. The work was described in a technical paper that appeared in conference proceedings and a Master's thesis, which were previously submitted to NASA. The present report describes some additional thermal modeling work done subsequently, and includes listings of computer codes developed during the project. Recommendations for future work are provided.

  11. Optimum conditions for adsorptive storage.

    PubMed

    Bhatia, Suresh K; Myers, Alan L

    2006-02-14

    The storage of gases in porous adsorbents, such as activated carbon and carbon nanotubes, is examined here thermodynamically from a systems viewpoint, considering the entire adsorption-desorption cycle. The results provide concrete objective criteria to guide the search for the "Holy Grail" adsorbent, for which the adsorptive delivery is maximized. It is shown that, for ambient temperature storage of hydrogen and delivery between 30 and 1.5 bar pressure, for the optimum adsorbent the adsorption enthalpy change is 15.1 kJ/mol. For carbons, for which the average enthalpy change is typically 5.8 kJ/mol, an optimum operating temperature of about 115 K is predicted. For methane, an optimum enthalpy change of 18.8 kJ/mol is found, with the optimum temperature for carbons being 254 K. It is also demonstrated that for maximum delivery of the gas the optimum adsorbent must be homogeneous, and that introduction of heterogeneity, such as by ball milling, irradiation, and other means, can only provide small increases in physisorption-related delivery for hydrogen. For methane, heterogeneity is always detrimental, at any value of average adsorption enthalpy change. These results are confirmed with the help of experimental data from the literature, as well as extensive Monte Carlo simulations conducted here using slit pore models of activated carbons as well as atomistic models of carbon nanotubes. The simulations also demonstrate that carbon nanotubes offer little or no advantage over activated carbons in terms of enhanced delivery, when used as storage media for either hydrogen or methane. PMID:16460092

  12. Absorption, Distribution, Metabolism, and Excretion of 2,2-Bis(bromomethyl)-1,3-propanediol in Male Fischer-344 Rats

    PubMed Central

    Hoehle, Simone I.; Knudsen, Gabriel A.; Sanders, J. Michael; Sipes, I. Glenn

    2009-01-01

    2,2-Bis(bromomethyl)-1,3-propanediol (BMP) is a brominated flame retardant, previously shown to be a multisite carcinogen in experimental animals. Studies were performed to characterize the dispositional and metabolic fate of BMP after oral or intravenous administration to male Fischer-344 rats. After a single oral administration of [14C]BMP (10 or 100 mg/kg) >80% of the low dose and 48% of the high dose were excreted by 12 h in the urine predominantly as a glucuronide metabolite. After repeated daily oral doses for 5 or 10 days, route and rate of elimination were similar to those obtained after single administrations of BMP. In all studies, the radioactivity recovered in feces was low (<15%). The total amount of radioactivity remaining in tissues at 72 h after a single oral administration of BMP (100 mg/kg) was less than 1% of the dose, and repeated daily dosing did not lead to retention in tissues. After intravenous administration, the radiolabel found in blood decreased rapidly. Excretion profiles were similar to those after oral administration. Parent BMP and BMP glucuronide were present in blood plasma after oral or intravenous dosing. After an intravenous dose of BMP (15 mg/kg) the hepatic BMP glucuronide was primarily exported into the bile (>50% within 6 h), but it underwent enterohepatic recycling with subsequent elimination in the urine. These data indicate that the extensive extraction and rapid glucuronidation by the liver limits exposure of internal tissues to BMP by greatly reducing its systemic bioavailability after oral exposure. PMID:19029203

  13. Approaches to mitigate the impact of dissolved organic matter on the adsorption of synthetic organic contaminants by porous carbonaceous sorbents

    SciTech Connect

    Yanping Guo; Abhishek Yadav; Tanju Karanfil

    2007-11-15

    Adsorption of trichloroethylene (TCE) and atrazine, two synthetic organic contaminants (SOCs) having different optimum adsorption pore regions, by four activated carbons and an activated carbon fiber (ACF) was examined. Adsorbents included two coconut-shell based granular activated carbons (GACs), two coal-based GACs (F400 and HD4000) and a phenol formaldehyde-based activated carbon fiber. The selected adsorbents had a wide range of pore size distributions but similar surface acidity and hydrophobicity. Single solute and preloading (with a dissolved organic matter (DOM)) isotherms were performed. Single solute adsorption results showed that (i) the adsorbents having higher amounts of pores with sizes about the dimensions of the adsorbate molecules exhibited higher uptakes, (ii) there were some pore structure characteristics, which were not completely captured by pore size distribution analysis, that also affected the adsorption, and (iii) the BET surface area and total pore volume were not the primary factors controlling the adsorption of SOCs. The preloading isotherm results showed that for TCE adsorbing primarily in pores <10 {angstrom}, the highly microporous ACF and GACs, acting like molecular sieves, exhibited the highest uptakes. For atrazine with an optimum adsorption pore region of 10-20 {angstrom}, which overlaps with the adsorption region of some DOM components, the GACs with a broad pore size distribution and high pore volumes in the 10-20 {angstrom} region had the least impact of DOM on the adsorption. 25 refs., 3 figs., 3 tabs.

  14. Adsorptive properties of flyash carbon

    SciTech Connect

    Graham, U.M.; Rathbone, R.F.; Robl, T.L.

    1996-10-01

    Flyash carbon constitutes the char particles that are left in flyash after the incomplete combustion of coal in the furnace, rendering flyash above spec for ASTM C618 applications for cement. A beneficiation process allows the selective separation of unburned carbon from flyash to be used for upgrading into a higher value product. Flyash carton is composed of several microscopically distinguishable types; inertinite is relatively unreactive in the thermal processing of coal and occurs essentially unaltered in the flyash while {open_quotes}coke{close_quotes} is produced from the melting, devolatilization, swelling and resolidification of the reactive macerals vitrinite and liptinite. The porosity, surface area, and surface chemistry of flyash carbons are characterized using mercury porosimetry, BET analysis, and vapor- and liquid-phase adsorption of various organic compounds. Results suggest that different carbon forms in flyash affect the degree of adsorption of phenols as will as other hydrocarbon pollutants onto the flyash carbon. A comparison of adsorptability of the flyash carbon compared to commercially available active carbons are discussed.

  15. Nitrile Metabolizing Yeasts

    NASA Astrophysics Data System (ADS)

    Bhalla, Tek Chand; Sharma, Monica; Sharma, Nitya Nand

    Nitriles and amides are widely distributed in the biotic and abiotic components of our ecosystem. Nitrile form an important group of organic compounds which find their applications in the synthesis of a large number of compounds used as/in pharmaceutical, cosmetics, plastics, dyes, etc>. Nitriles are mainly hydro-lyzed to corresponding amide/acid in organic chemistry. Industrial and agricultural activities have also lead to release of nitriles and amides into the environment and some of them pose threat to human health. Biocatalysis and biotransformations are increasingly replacing chemical routes of synthesis in organic chemistry as a part of ‘green chemistry’. Nitrile metabolizing organisms or enzymes thus has assumed greater significance in all these years to convert nitriles to amides/ acids. The nitrile metabolizing enzymes are widely present in bacteria, fungi and yeasts. Yeasts metabolize nitriles through nitrilase and/or nitrile hydratase and amidase enzymes. Only few yeasts have been reported to possess aldoxime dehydratase. More than sixty nitrile metabolizing yeast strains have been hither to isolated from cyanide treatment bioreactor, fermented foods and soil. Most of the yeasts contain nitrile hydratase-amidase system for metabolizing nitriles. Transformations of nitriles to amides/acids have been carried out with free and immobilized yeast cells. The nitrilases of Torulopsis candida>and Exophiala oligosperma>R1 are enantioselec-tive and regiospecific respectively. Geotrichum>sp. JR1 grows in the presence of 2M acetonitrile and may have potential for application in bioremediation of nitrile contaminated soil/water. The nitrilase of E. oligosperma>R1 being active at low pH (3-6) has shown promise for the hydroxy acids. Immobilized yeast cells hydrolyze some additional nitriles in comparison to free cells. It is expected that more focus in future will be on purification, characterization, cloning, expression and immobilization of nitrile metabolizing

  16. Microstructure-Dependent Gas Adsorption: Accurate Predictions of Methane Uptake in Nanoporous Carbons

    SciTech Connect

    Ihm, Yungok; Cooper, Valentino R; Gallego, Nidia C; Contescu, Cristian I; Morris, James R

    2014-01-01

    We demonstrate a successful, efficient framework for predicting gas adsorption properties in real materials based on first-principles calculations, with a specific comparison of experiment and theory for methane adsorption in activated carbons. These carbon materials have different pore size distributions, leading to a variety of uptake characteristics. Utilizing these distributions, we accurately predict experimental uptakes and heats of adsorption without empirical potentials or lengthy simulations. We demonstrate that materials with smaller pores have higher heats of adsorption, leading to a higher gas density in these pores. This pore-size dependence must be accounted for, in order to predict and understand the adsorption behavior. The theoretical approach combines: (1) ab initio calculations with a van der Waals density functional to determine adsorbent-adsorbate interactions, and (2) a thermodynamic method that predicts equilibrium adsorption densities by directly incorporating the calculated potential energy surface in a slit pore model. The predicted uptake at P=20 bar and T=298 K is in excellent agreement for all five activated carbon materials used. This approach uses only the pore-size distribution as an input, with no fitting parameters or empirical adsorbent-adsorbate interactions, and thus can be easily applied to other adsorbent-adsorbate combinations.

  17. Prediction of iodide adsorption on oxides by surface complexation modeling with spectroscopic confirmation.

    PubMed

    Nagata, Takahiro; Fukushi, Keisuke; Takahashi, Yoshio

    2009-04-15

    A deficiency in environmental iodine can cause a number of health problems. Understanding how iodine is sequestered by materials is helpful for evaluating and developing methods for minimizing human health effects related to iodine. In addition, (129)I is considered to be strategically important for safety assessment of underground radioactive waste disposal. To assess the long-term stability of disposed radioactive waste, an understanding of (129)I adsorption on geologic materials is essential. Therefore, the adsorption of I(-) on naturally occurring oxides is of environmental concern. The surface charges of hydrous ferric oxide (HFO) in NaI electrolyte solutions were measured by potentiometric acid-base titration. The surface charge data were analyzed by means of an extended triple-layer model (ETLM) for surface complexation modeling to obtain the I(-) adsorption reaction and its equilibrium constant. The adsorption of I(-) was determined to be an outer-sphere process from ETLM analysis, which was consistent with independent X-ray absorption near-edge structure (XANES) observation of I(-) adsorbed on HFO. The adsorption equilibrium constants for I(-) on beta-TiO(2) and gamma-Al(2)O(3) were also evaluated by analyzing the surface charge data of these oxides in NaI solution as reported in the literature. Comparison of these adsorption equilibrium constants for HFO, beta-TiO(2), and gamma-Al(2)O(3) based on site-occupancy standard states permitted prediction of I(-) adsorption equilibrium constants for all oxides by means of the Born solvation theory. The batch adsorption data for I(-) on HFO and amorphous aluminum oxide were reasonably reproduced by ETLM with the predicted equilibrium constants, confirming the validity of the present approach. Using the predicted adsorption equilibrium constants, we calculated distribution coefficient (K(d)) values for I(-) adsorption on common soil minerals as a function of pH and ionic strength. PMID:19176225

  18. Metabolic Syndrome

    MedlinePlus

    ... If you already have metabolic syndrome, making these healthy lifestyle choices can help reduce your risk of heart disease and other health problems. If lifestyle changes alone can’t control your ... to help. Maintain a healthy weight Your doctor can measure your body mass ...

  19. Metabolic Syndrome

    MedlinePlus

    ... from Nemours for Parents for Kids for Teens Teens Home Body Mind Sexual Health Food & Fitness Diseases & Conditions Infections Q&A School & Jobs Drugs & Alcohol Staying Safe Recipes En Español Making a Change – Your Personal Plan Hot ... > Metabolic Syndrome Print A A A Text Size ...

  20. Metabolic Analysis

    NASA Astrophysics Data System (ADS)

    Tolstikov, Vladimir V.

    Analysis of the metabolome with coverage of all of the possibly detectable components in the sample, rather than analysis of each individual metabolite at a given time, can be accomplished by metabolic analysis. Targeted and/or nontargeted approaches are applied as needed for particular experiments. Monitoring hundreds or more metabolites at a given time requires high-throughput and high-end techniques that enable screening for relative changes in, rather than absolute concentrations of, compounds within a wide dynamic range. Most of the analytical techniques useful for these purposes use GC or HPLC/UPLC separation modules coupled to a fast and accurate mass spectrometer. GC separations require chemical modification (derivatization) before analysis, and work efficiently for the small molecules. HPLC separations are better suited for the analysis of labile and nonvolatile polar and nonpolar compounds in their native form. Direct infusion and NMR-based techniques are mostly used for fingerprinting and snap phenotyping, where applicable. Discovery and validation of metabolic biomarkers are exciting and promising opportunities offered by metabolic analysis applied to biological and biomedical experiments. We have demonstrated that GC-TOF-MS, HPLC/UPLC-RP-MS and HILIC-LC-MS techniques used for metabolic analysis offer sufficient metabolome mapping providing researchers with confident data for subsequent multivariate analysis and data mining.

  1. Zinc isotope fractionation during surface adsorption by bacteria

    NASA Astrophysics Data System (ADS)

    Kafantaris, F. A.; Borrok, D. M.

    2011-12-01

    The cycling and transport of zinc (Zn) in natural waters is partly controlled by its adsorption and uptake by bacterial communities. These reactions are reflected in changes in the ratios of stable Zn isotopes; however, the magnitudes and directions of these changes are largely unconstrained. In the current work, we attempt to define Zn isotope fractionation factors for bacteria-Zn interactions by performing adsorption experiments with representative Gram-positive (Bacillus subtilis) and Gram-negative (Pseudomonas mendocina) bacteria. Experiments included, (1) pH-dependent adsorption using differing bacteria:Zn ratios, (2) Zn loading at constant pH, and (3) kinetics and reversibility experiments. Results indicate that Zn adsorption is fully reversible for both bacterial species. Moreover, under the same experimental conditions both bacterial species adsorbed Zn to similar extents. Initial isotopic analysis (using a Nu Instruments MC-ICP-MS) demonstrates that, as the extent of adsorption increases, the heavier Zn isotopes are preferentially incorporated as bacterial-surface complexes. Under conditions of low bacteria:Zn ratio, the Δ66Znbacteria-solution was about 0.3% for both bacterial species. This separation factor is similar to that found in other studies involving the complexation of Zn with biologic or organic components. For example, the complexation of Zn with Purified Humic Acid (PHA) resulted in a Δ66ZnPHA-solution of +0.24% [1], and sorption of Zn onto two separate diatom species resulted in Δ66Znsolid-solution of +0.43% and +0.27%, respectively [2]. These results suggest that Zn complexation with functional groups common to bacteria and natural organic matter may be a process that universally incorporates the heavier Zn isotopes. Our current work is focused on quantifying Zn isotope fractionation during metabolic incorporation by separating this effect from surface adsorption reactions. [1] Jouvin et al., (2009) Environ. Sci. Technol., 43(15) 5747

  2. Distribution and metabolism of intravenously administered choline[methyl- 3-H] and synthesis in vivo of acetylcholine in various tissues of guinea pigs.

    PubMed

    Haubrich, D R; Wang, P F; Wedeking, P W

    1975-04-01

    that behaved like either phosphorylcholine or betaine during paper electrophoresis and chromatography. Betaine was the principal metabolite of choline in plasma. Radioactivity was excreted slowly into urine, which contained primarily free choline, betaine and a large amount of an unidentified metabolite. These findings indicate that the principal mechanism for the rapid removal of choline from plasma is uptake into tissues followed by metabolism. PMID:1133767

  3. Flavonoid interactions during digestion, absorption, distribution and metabolism: a sequential structure-activity/property relationship-based approach in the study of bioavailability and bioactivity.

    PubMed

    Gonzales, Gerard Bryan; Smagghe, Guy; Grootaert, Charlotte; Zotti, Moises; Raes, Katleen; Van Camp, John

    2015-05-01

    Flavonoids are a group of polyphenols that provide health-promoting benefits upon consumption. However, poor bioavailability has been a major hurdle in their use as drugs or nutraceuticals. Low bioavailability has been associated with flavonoid interactions at various stages of the digestion, absorption and distribution process, which is strongly affected by their molecular structure. In this review, we use structure-activity/property relationship to discuss various flavonoid interactions with food matrices, digestive enzymes, intestinal transporters and blood proteins. This approach reveals specific bioactive properties of flavonoids in the gastrointestinal tract as well as various barriers for their bioavailability. In the last part of this review, we use these insights to determine the effect of different structural characteristics on the overall bioavailability of flavonoids. Such information is crucial when flavonoid or flavonoid derivatives are used as active ingredients in foods or drugs. PMID:25633078

  4. Genesis of ion-adsorption type REE ores in Thailand

    NASA Astrophysics Data System (ADS)

    Sanematsu, K.; Yoshiaki, K.; Watanabe, Y.

    2012-04-01

    Ion-adsorption type REE deposits, which have been economically mined only in southern China, are predominant supply sources for HREE in the world. The ore bodies consist of weathered granites called ion-adsorption ores. The majority of REE (>50 %) are electrostatically adsorbed onto weathering products in the ores and they can be extracted by ion exchange using an electrolyte solution (e.g., ammonium sulfate solution). Recently the occurrences of ion-adsorption ores have been reported in Indochina, SE Asia. In this study, we discuss geochemical and mineralogical characteristics of parent granites and weathered granites in Thailand in order to reveal the genesis of ion-adsorption ores. Permo-Triassic and Cretaceous-Paleogene granite plutons are distributed from northern Thailand to western Indonesia through eastern Myanmar and Peninsular Malaysia. They are mostly ilmenite-series calcalkaline biotite or hornblende-biotite granites. REE contents of the granites range from 60 to 600 ppm and they are relatively high in Peninsula Thailand. REE-bearing minerals consist mainly of apatite, zircon, allanite, titanite, monazite and xenotime. Some I-type granites contain REE fluorocarbonate (probably synchysite-(Ce)) in cavities and cracks in feldspars and it is the dominant source of REE for ion-adsorption ores because the fluorocarbonate is easily soluble during weathering. In contrast, insoluble monazite and xenotime are not preferable for ion-adsorption ores although they are common ore minerals of placer REE deposits. Weathered granites show REE contents ranging from 60 to 1100 ppm in Thailand because REE are relatively immobile compared with mobile elements (e.g., Na, K, Ca). In the weathered granites, REE are contained in residual minerals and secondary minerals and are adsorbed onto the surface of weathering products. A weathering profile of granite with ion-adsorption type mineralization can be divided into upper and lower parts based on REE enrichment and Ce

  5. Absorption, distribution, metabolism and excretion of the novel SARM GTx-024 [(S)-N-(4-cyano-3-(trifluoromethyl)phenyl)-3-(4-cyanophenoxy)-2-hydroxy-2-methylpropanamide] in rats.

    PubMed

    Kim, Juhyun; Wang, Ronghua; Veverka, Karen A; Dalton, James T

    2013-11-01

    1. GTx-024, a novel selective androgen receptor modulator, is currently being investigated as an oral treatment for muscle wasting disorders associated with cancer and other chronic conditions. 2. Absorption of GTx-024 was rapid and complete, with high oral bioavailability. A wide tissue distribution of [(14)C]GTx-024 derived radioactivity was observed. [(14)C]GTx-024-derived radioactivity had a moderate plasma clearance (117.7 and 74.5 mL/h/kg) and mean elimination half-life of 0.6 h and 16.4 h in male and female rats, respectively. 3. Fecal excretion was the predominant route of elimination, with ∼70% of total radioactivity recovered in feces and 21-25% in urine within 48 h. Feces of intact rats contained primarily unchanged [(14)C]GTx-024 (49.3-64.6%). Metabolites were identified in urine and feces resulting from oxidation of the cyanophenol ring (M8, 17.6%), hydrolysis and/or further conjugation of the amide moiety (M3, 8-12%) and the cyanophenol ring (M4, 1.3-1.5%), and glucuronidation of [(14)C]GTx-024 at the tertiary alcohol (M6, 3.5-3.7%). There was no quantifiable metabolite in plasma. 4. In summary, in the rat GTx-024 is completely absorbed, widely distributed, biotransformed through several metabolic pathways, and eliminated in feces primarily as an unchanged drug. PMID:24074268

  6. Absorption, distribution, metabolism, excretion, and kinetics of 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoic acid ammonium salt following a single dose in rat, mouse, and cynomolgus monkey.

    PubMed

    Gannon, Shawn A; Fasano, William J; Mawn, Michael P; Nabb, Diane L; Buck, Robert C; Buxton, L William; Jepson, Gary W; Frame, Steven R

    2016-01-18

    Ammonium, 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-propanoate has been developed as a processing aid used in the manufacture of fluoropolymers. The absorption, distribution, elimination, and distribution (ADME) and kinetic behavior of this substance has been evaluated in rats, mice, and cynomolgus monkeys by oral and intravenous routes of exposure and studied in both plasma and urine. The test substance is rapidly and completely absorbed in both rats and mice and both in vivo and in vitro experiments indicate that it is not metabolized. The test substance is rapidly eliminated exclusively in the urine in both rats and mice, with rats eliminating it more quickly than mice (approximately 5h elimination half-life in rats, 20 h half-life in mice). Pharmacokinetic analysis in monkeys, rats, and mice indicate rapid, biphasic elimination characterized by a very fast alpha phase and a slower beta phase. The beta phase does not contribute to potential accumulation after multiple dosing in rats or monkeys. Comparative pharmacokinetics in rats, mice, and monkeys indicates that the rat is more similar to the monkey and is therefore a more appropriate rodent model for pharmacokinetics in primates. PMID:26743852

  7. Can you boost your metabolism?

    MedlinePlus

    Resting metabolism rate (RMR); Total daily energy expenditure (TDEE); Non-exercise activity thermogenesis (NEAT); Weight loss - metabolism; Overweight - metabolism; Obesity - metabolism; Diet - metabolism

  8. Adsorption of copper to different biogenic oyster shell structures

    NASA Astrophysics Data System (ADS)

    Wu, Qiong; Chen, Jie; Clark, Malcolm; Yu, Yan

    2014-08-01

    The removal of copper from solution by oyster shell powder was investigated for potential wastewater treatment uses. In particular, adsorption behavior differences between the prismatic (PP) and nacreous (NP) shell layers, and how this affects copper removal, were investigated. Experimental results indicated that copper adsorption was highly pH-dependent with optimal copper removal at pH 5.5, where the powdered whole raw shell (RP) removed up to 99.9% of the copper within 24 h at a 10 mg/L initial copper concentration. Langmuir and Freundlich models were used to analyze the isotherm PP, NP and RP data. These results showed a strong homogeneous Langmuir model for low initial copper concentrations (5-30 mg/L) to both RP and PP layer, while strong agreement with a heterogeneous Freundlich model for high initial copper concentrations (30-200 mg/L); nevertheless, a homogeneous Langmuir model provided the best fit for the more dense NP layer across the initial concentration range (5-200 mg/L). The distribution coefficient (Kd) value of PP layer for each initial concentration investigated was substantially higher than the NP layer and it was also found that the PP layer dominated the adsorption process with an adsorption capacity of 8.9 mg/g, while the adsorption capacity of the NP layer was 2.6 mg/g. These differences are believed to be because of the more porous structure of the PP layer, which was confirmed by scanning electron microscopy, infrared spectroscopy, energy-dispersive X-ray spectroscopy, and thermogravimetry-differential thermal analyses.

  9. Interfacial adsorption of antifreeze proteins: a neutron reflection study.

    PubMed

    Xu, Hai; Perumal, Shiamalee; Zhao, Xiubo; Du, Ning; Liu, Xiang-Yang; Jia, Zongchao; Lu, Jian R

    2008-06-01

    Interfacial adsorption from two antifreeze proteins (AFP) from ocean pout (Macrozoarces americanus, type III AFP, AFP III, or maAFP) and spruce budworm (Choristoneura fumiferana, isoform 501, or cfAFP) were studied by neutron reflection. Hydrophilic silicon oxide was used as model substrate to facilitate the solid/liquid interfacial measurement so that the structural features from AFP adsorption can be examined. All adsorbed layers from AFP III could be modeled into uniform layer distribution assuming that the protein molecules were adsorbed with their ice-binding surface in direct contact with the SiO(2) substrate. The layer thickness of 32 A was consistent with the height of the molecule in its crystalline form. With the concentration decreasing from 2 mg/ml to 0.01 mg/ml, the volume fraction of the protein packed in the monolayer decreased steadily from 0.4 to 0.1, consistent with the concentration-dependent inhibition of ice growth observed over the range. In comparison, insect cfAFP showed stronger adsorption over the same concentration range. Below 0.1 mg/ml, uniform layers were formed. But above 1 mg/ml, the adsorbed layers were characterized by a dense middle layer and two outer diffuse layers, with a total thickness around 100 A. The structural transition indicated the responsive changes of conformational orientation to increasing surface packing density. As the higher interfacial adsorption of cfAFP was strongly correlated with the greater thermal hysteresis of spruce budworm, our results indicated the important relation between protein adsorption and antifreeze activity. PMID:18234809

  10. Adsorption of goethite onto quartz and kaolinite

    USGS Publications Warehouse

    Goldberg, M.C.; Weiner, Eugene R.; Boymel, P.M.

    1984-01-01

    The adsorption of colloidal goethite onto quartz and kaolinite substrates has been studied as a function of pH and NaCl concentration. Goethite adsorption was measured quantitatively by Fourier-transform infrared spectroscopy. The results indicate that adsorption onto both substrates is due primarily to coulombic forces; however, the pH dependence of adsorption is very different for the two substrates. This is explained by the fact that the surface charge on quartz is entirely pH-dependent, while kaolinite has surface faces which carry a permanent negative charge. Adsorption of goethite on to kaolinite increases markedly with increasing NaCl concentration, while adsorption onto quartz is relatively independent of NaCl concentration. This can be explained by the influence of NaCl concentration upon the development of surface charge on the substrates. A method is described for separating surface-bound goethite from free goethite.

  11. Role of air bubbles overlooked in the adsorption of perfluorooctanesulfonate on hydrophobic carbonaceous adsorbents.

    PubMed

    Meng, Pingping; Deng, Shubo; Lu, Xinyu; Du, Ziwen; Wang, Bin; Huang, Jun; Wang, Yujue; Yu, Gang; Xing, Baoshan

    2014-12-01

    Hydrophobic interaction has been considered to be responsible for adsorption of perfluorooctanesulfonate (PFOS) on the surface of hydrophobic adsorbents, but the long C-F chain in PFOS is not only hydrophobic but also oleophobic. In this study, for the first time we propose that air bubbles on the surface of hydrophobic carbonaceous adsorbents play an important role in the adsorption of PFOS. The level of adsorption of PFOS on carbon nanotubes (CNTs), graphite (GI), graphene (GE), and powdered activated carbon (PAC) decreases after vacuum degassing. Vacuum degassing time and pressure significantly affect the removal of PFOS by these adsorbents. After vacuum degassing at 0.01 atm for 36 h, the extent of removal of PFOS by the pristine CNTs and GI decreases 79% and 74%, respectively, indicating the main contribution of air bubbles to PFOS adsorption. When the degassed solution is recontacted with air during the adsorption process, the removal of PFOS recovers to the value obtained without vacuum degassing, further verifying the key role of air bubbles in PFOS adsorption. By theoretical calculation, the distribution of PFOS in air bubbles on the adsorbent surfaces is discussed, and a new schematic sorption model of PFOS on carbonaceous adsorbents in the presence of air bubbles is proposed. The accumulation of PFOS at the interface of air bubbles on the adsorbents is primarily responsible for its adsorption, providing a new mechanistic insight into the transport, fate, and removal of PFOS. PMID:25365738

  12. Methane adsorption in nanoporous carbon: the numerical estimation of optimal storage conditions

    NASA Astrophysics Data System (ADS)

    Ortiz, L.; Kuchta, B.; Firlej, L.; Roth, M. W.; Wexler, C.

    2016-05-01

    The efficient storage and transportation of natural gas is one of the most important enabling technologies for use in energy applications. Adsorption in porous systems, which will allow the transportation of high-density fuel under low pressure, is one of the possible solutions. We present and discuss extensive grand canonical Monte Carlo (GCMC) simulation results of the adsorption of methane into slit-shaped graphitic pores of various widths (between 7 Å and 50 Å), and at pressures P between 0 bar and 360 bar. Our results shed light on the dependence of film structure on pore width and pressure. For large widths, we observe multi-layer adsorption at supercritical conditions, with excess amounts even at large distances from the pore walls originating from the attractive interaction exerted by a very high-density film in the first layer. We are also able to successfully model the experimental adsorption isotherms of heterogeneous activated carbon samples by means of an ensemble average of the pore widths, based exclusively on the pore-size distributions (PSD) calculated from subcritical nitrogen adsorption isotherms. Finally, we propose a new formula, based on the PSD ensemble averages, to calculate the isosteric heat of adsorption of heterogeneous systems from single-pore-width calculations. The methods proposed here will contribute to the rational design and optimization of future adsorption-based storage tanks.

  13. Assessing compartmentalized flux in lipid metabolism with isotopes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Metabolism in plants takes place across multiple cell types and subpopulations in distinct organelles. The distributions equate to spatial heterogeneity; though the limited means to experimentally asses metabolism frequently involve homogenizing tissues and mixing metabolites from different location...

  14. Disorders of Lipid Metabolism

    MedlinePlus

    ... Metabolic Disorders Disorders of Carbohydrate Metabolism Disorders of Amino Acid Metabolism Disorders of Lipid Metabolism Fats (lipids) are ... carbohydrates and low in fats. Supplements of the amino acid carnitine may be helpful. The long-term outcome ...

  15. Adsorption of organic molecules on silica surface.

    PubMed

    Parida, Sudam K; Dash, Sukalyan; Patel, Sabita; Mishra, B K

    2006-09-13

    The adsorption behaviour of various organic adsorbates on silica surface is reviewed. Most of the structural information on silica is obtained from IR spectral data and from the characteristics of water present at the silica surface. Silica surface is generally embedded with hydroxy groups and ethereal linkages, and hence considered to have a negative charged surface prone to adsorption of electron deficient species. Adsorption isotherms of the adsorbates delineate the nature of binding of the adsorbate with silica. Aromatic compounds are found to involve the pi-cloud in hydrogen bonding with silanol OH group during adsorption. Cationic and nonionic surfactants adsorb on silica surface involving hydrogen bonding. Sometimes, a polar part of the surfactants also contributes to the adsorption process. Styryl pyridinium dyes are found to anchor on silica surface in flat-on position. On modification of the silica by treating with alkali, the adsorption behaviour of cationic surfactant or polyethylene glycol changes due to change in the characteristics of silica or modified silica surface. In case of PEG-modified silica, adsolubilization of the adsorbate is observed. By using a modified adsorption equation, hemimicellization is proposed for these dyes. Adsorptions of some natural macromolecules like proteins and nucleic acids are investigated to study the hydrophobic and hydrophilic binding sites of silica. Artificial macromolecules like synthetic polymers are found to be adsorbed on silica surface due to the interaction of the multifunctional groups of the polymers with silanols. Preferential adsorption of polar adsorbates is observed in case of adsorbate mixtures. When surfactant mixtures are considered to study competitive adsorption on silica surface, critical micelle concentration of individual surfactant also contributes to the adsorption isotherm. The structural study of adsorbed surface and the thermodynamics of adsorption are given some importance in this review

  16. Volumetric interpretation of protein adsorption kinetics

    NASA Astrophysics Data System (ADS)

    Barnthip, Naris

    Protein adsorption is believed to be a very important factor ultimately leading to a predictive basis for biomaterials design and improving biocompatibility. Standard adsorption theories are modified to accommodate experimental observations. Adsorption from single-protein solutions and competitive adsorption from binary solutions are mainly considered. The standard solution-depletion method of measuring protein adsorption is implemented with SDS-gel electrophoresis as a multiplexing, separation-and-quantification tool to measure protein adsorption to hydrophobic octyl sepharose (OS) adsorbent particles. Standard radiometric methods have also been used as a further check on the electrophoresis method mentioned above for purified-protein cases. Experimental results are interpreted in terms of an alternative kinetic model called volumetric interpretation of protein adsorption. A partitioning process between bulk solution and a three-dimensional interphase region that separates bulk solution from the physical adsorbent surface is the concept of the model. Protein molecules rapidly diffuse into an inflating interphase that is spontaneously formed by bringing a protein solution into contact with a physical surface, then follows by rearrangement of proteins within this interphase to achieve the maximum interphase concentration (dictated by energetics of interphase dehydration) within the thinnest (lowest volume) interphase possible. An important role of water in protein adsorption is emphasized and supported by this model. The fundamental aspects including the reversibility/irreversibility of protein adsorption, the multilayer adsorption, the applicability of thermodynamic/computational models, the capacity of protein adsorption, and the mechanism of so called Vroman effect are discussed and compared to the conventional theories. Superhydrophobic effect on the adsorption of human serum albumin is also examined.

  17. Ozone adsorption on carbon nanoparticles

    NASA Astrophysics Data System (ADS)

    Chassard, Guillaume; Gosselin, Sylvie; Visez, Nicolas; Petitprez, Denis

    2014-05-01

    Carbonaceous particles produced by incomplete combustion or thermal decomposition of hydrocarbons are ubiquitous in the atmosphere. On these particles are adsorbed hundreds of chemical species. Those of great concern to health are polycyclic aromatic hydrocarbons (PAHs). During atmospheric transport, particulate PAHs react with gaseous oxidants. The induced chemical transformations may change toxicity and hygroscopicity of these potentially inhalable particles. The interaction between ozone and carbon particles has been extensively investigated in literature. However ozone adsorption and surface reaction mechanisms are still ambiguous. Some studies described a fast catalytic decomposition of ozone initiated by an atomic oxygen chemisorption followed by a molecular oxygen release [1-3]. Others suggested a reversible ozone adsorption according to Langmuir-type behaviour [4,5]. The aim of this present study is a better understanding of ozone interaction with carbon surfaces. An aerosol of carbon nanoparticles was generated by flowing synthetic air in a glass tube containing pure carbon (primary particles < 50 nm), under magnetic stirring. The aerosol was then mixed with ozone in an aerosol flow tube. Ozone uptake experiments were performed with different particles concentrations with a fixed ozone concentration. The influence of several factors on kinetics was examined: initial ozone concentration, particle size (50 nm ≤ Dp ≤ 200 nm) and competitive adsorption (with probe molecule and water). The effect of initial ozone concentration was first studied. Accordingly to literature, it has been observed that the number of gas-phase ozone molecules lost per unit particle surface area tends towards a plateau for high ozone concentration suggesting a reversible ozone adsorption according to a Langmuir mechanism. We calculated the initial reaction probability between O3 and carbon particles.An initial uptake coefficient of 1.10-4 was obtained. Similar experiments were

  18. [Influence of Three Low-Molecular-Weight Organic Acids on the Adsorption of Phenanthrene in Purple Soil].

    PubMed

    Xie, Li; Chen, Ben-shou; Zhang, Jin-zhong; Lu, Song; Jiang, Tao

    2016-03-15

    The effects of three low-molecular-weight organic acids (citric acid, malic acid and oxalic acid) on the adsorption of phenanthrene in purple soil were studied by static adsorption experiment. The results showed that the adsorption kinetic process of phenanthrene in purple soil could be described by the second-order kinetic model, and the adsorption rate constant would significantly decrease in the presence of the three low-molecular-weight organic acids ( LMWOAs). The adsorption thermodynamic process could be well described by linear adsorption model, which was dominated by distribution role. The three LMWOAs could promote the adsorption of phenantherene in purple soil when their concentrations were less than 5 mmol · L⁻¹, whereas inhibit the adsorption when their concentrations were more than 10 mmol · L⁻¹, and the inhibition would increase with increasing concentrations. Moreover, the inhibitory ability displayed a decreasing order of citric acid, oxalic acid, and malic acid when their concentrations were 20 mmol · L⁻¹, which is related to the molecular structure and acidity of the three LMWOAs. Compared with the control, the content of dissolved organic matter (DOM) released from purple soil showed a trend of first decrease and then increase with increasing LMWOAs concentration, and the adsorption capacity of phenanthrene in purple soil was negatively related to DOM content. PMID:27337897

  19. Analyzing adsorption characteristics of CO2, N2 and H2O in MCM-41 silica by molecular simulation

    NASA Astrophysics Data System (ADS)

    Chang, Shing-Cheng; Chien, Shih-Yao; Chen, Chieh-Li; Chen, Cha'o.-Kuang

    2015-03-01

    The adsorption characteristics of carbon dioxide, nitrogen and water molecules in MCM-41 mesoporous molecular sieve have been investigated by the molecular simulation. We evaluate the pressure-adsorption isotherms and adsorption density profiles under variant gas pressure, operating temperature and mesopore radius of MCM-41 by the grand canonical Monte Carlo simulation. According to the calculated adsorption energy distributions, the adsorption mechanisms of gas in MCM-41 are mainly divided into three types, namely "surface adsorption" on the pore wall, "multilayer adsorption" on the adsorbed gas molecules and "molecular self-aggregation" near the pore center. In addition, the adsorption characteristics of water molecules in MCM-41 are found to be quite different from those of carbon dioxide and nitrogen due to the hydrogen bonds effect. The results indicate that the MCM-41 is practicable in engineering application for the capture, storage, and re-use of water molecules, since it is temperature-sensitive and can achieve significant adsorption loadings within a small range of pressure values via the capillary condensation phenomena.

  20. Adsorption of phenol on wood surfaces

    NASA Astrophysics Data System (ADS)

    Mamleeva, N. A.; Lunin, V. V.

    2016-03-01

    Adsorption of phenol on aspen and pine wood is investigated. It is shown that adsorption isotherms are described by the Langmuir model. The woods' specific surface areas and adsorption interaction constants are determined. It is found that the sorption of phenol on surfaces of aspen and pine is due to Van der Waals interactions ( S sp = 45 m2/godw for aspen and 85 m2/godw for pine). The difference between the adsorption characteristics is explained by properties of the wood samples' microstructures.

  1. Adsorption of water vapor on reservoir rocks

    SciTech Connect

    Not Available

    1993-07-01

    Progress is reported on: adsorption of water vapor on reservoir rocks; theoretical investigation of adsorption; estimation of adsorption parameters from transient experiments; transient adsorption experiment -- salinity and noncondensible gas effects; the physics of injection of water into, transport and storage of fluids within, and production of vapor from geothermal reservoirs; injection optimization at the Geysers Geothermal Field; a model to test multiwell data interpretation for heterogeneous reservoirs; earth tide effects on downhole pressure measurements; and a finite-difference model for free surface gravity drainage well test analysis.

  2. Adsorption interactions of humic acids with biocides

    NASA Astrophysics Data System (ADS)

    Mal'Tseva, E. V.; Ivanov, A. A.; Yudina, N. V.

    2009-11-01

    The chemical composition of humic acids from brown coal (Aldrich) was determined by element analysis, 13C NMR spectroscopy, and potentiometric titration. The adsorption ability of humic acids with different biocides (cyproconasol, propiconasol, tebuconasol, irgarol 1051, and DCOIT) was studied. The adsorption ability of a mixture of biocides in aqueous solutions was higher than that of the individual components. The limiting concentration of humic acids at which adsorption of biocides was maximum was determined. Adsorption constants were calculated by the Freundlich equation for each biocide in aqueous solution.

  3. Adsorption and isotopic fractionation of Xe

    NASA Technical Reports Server (NTRS)

    Bernatowicz, T. J.; Podosek, F. A.

    1986-01-01

    A theoretical description of the mechanisms of isotopic fractionation arising during adsorption of noble gases in a Henry's Law pressure regime is given. Experimental data on the isotopic composition of Xe adsorbed on activated charcoal in the temperature range 220 K to 350 K are presented. Both theoretical considerations and the experimental data indicate that equilibrium adsorption does not significantly alter the isotopic structure of adsorbed structure of adsorbed noble gases. Therefore, if adsorption is responsible for the elemental noble gas pattern in meteorites and the earth, the heavy noble gas isotopic fractionation between them must have been produced prior to and by a different process than equilibrium adsorption.

  4. Moisture adsorption in optical coatings

    NASA Technical Reports Server (NTRS)

    Macleod, H. Angus

    1988-01-01

    The thin film filter is a very large aperture component which is exceedingly useful because of its small size, flexibility and ease of mounting. Thin film components, however, do have defects of performance and especially of stability which can cause problems in systems, particularly where long-term measurements are being made. Of all of the problems, those associated with moisture absorption are the most serious. Moisture absorption occurs in the pore-shaped voids inherent in the columnar structure of the layers. Ion-assisted deposition is a promising technique for substantially reducing moisture adsorption effects in thin film structures.

  5. Charcoal/Nitrogen Adsorption Cryocooler

    NASA Technical Reports Server (NTRS)

    Bard, Steven

    1987-01-01

    Refrigerator with no wear-related moving parts produces 0.5 W of cooling at 118 K. When fully developed, refrigerator needs no electrical power, and life expectancy of more than 10 yr, operates unattended to cool sensitive infrared detectors for long periods. Only moving parts in adsorption cryocooler are check valves. As charcoal is cooled in canister, gas pressure drops, allowing inlet check valve to open and admit more nitrogen. When canister is heated, pressure rises, closing inlet valve and eventually opening outlet valve.

  6. Characteristics of competitive adsorption between 2-methylisoborneol and natural organic matter on superfine and conventionally sized powdered activated carbons.

    PubMed

    Matsui, Yoshihiko; Yoshida, Tomoaki; Nakao, Soichi; Knappe, Detlef R U; Matsushita, Taku

    2012-10-01

    When treating water with activated carbon, natural organic matter (NOM) is not only a target for adsorptive removal but also an inhibitory substance that reduces the removal efficiency of trace compounds, such as 2-methylisoborneol (MIB), through adsorption competition. Recently, superfine (submicron-sized) activated carbon (SPAC) was developed by wet-milling commercially available powdered activated carbon (PAC) to a smaller particle size. It was reported that SPAC has a larger NOM adsorption capacity than PAC because NOM mainly adsorbs close to the external adsorbent particle surface (shell adsorption mechanism). Thus, SPAC with its larger specific external surface area can adsorb more NOM than PAC. The effect of higher NOM uptake on the adsorptive removal of MIB has, however, not been investigated. Results of this study show that adsorption competition between NOM and MIB did not increase when NOM uptake increased due to carbon size reduction; i.e., the increased NOM uptake by SPAC did not result in a decrease in MIB adsorption capacity beyond that obtained as a result of NOM adsorption by PAC. A simple estimation method for determining the adsorbed amount of competing NOM (NOM that reduces MIB adsorption) is presented based on the simplified equivalent background compound (EBC) method. Furthermore, the mechanism of adsorption competition is discussed based on results obtained with the simplified EBC method and the shell adsorption mechanism. Competing NOM, which likely comprises a small portion of NOM, adsorbs in internal pores of activated carbon particles as MIB does, thereby reducing the MIB adsorption capacity to a similar extent regardless of adsorbent particle size. SPAC application can be advantageous because enhanced NOM removal does not translate into less effective removal of MIB. Molecular size distribution data of NOM suggest that the competing NOM has a molecular weight similar to that of the target compound. PMID:22763287

  7. Enthalpy of adsorption and isotherms for adsorption of naphthenic acid onto clays

    SciTech Connect

    Zou, L.; Han, B.; Yan, H.; Kasperski, K.L.; Xu, Y.; Hepler, L.G.

    1997-06-15

    The enthalpies of adsorption and the isotherms for adsorption of naphthenic acid onto Na-montmorillonite, Na-kaolinite, and Na-illite were studied by means of calorimetry and the static method at 298.15 K. The results show that the enthalpies of adsorption and saturated adsorption amounts of naphthenic acid on different clays change in the order Na-montmorillonite > Na-illite > Na-kaolinite. The interaction between naphthenic acid and clays is discussed.

  8. MINERAL-SURFACTANT INTERACTIONS FOR MINIMUM REAGENTS PRECIPITATION AND ADSORPTION FOR IMPROVED OIL RECOVERY

    SciTech Connect

    P. Somasundaran

    2004-10-30

    Significant surfactant loss by adsorption or precipitation on reservoir minerals can cause chemical flooding processes to be less than satisfactory for enhanced oil recovery. This project is aimed towards an understanding of the role of reservoir minerals and their dissolved species in chemical loss by precipitation or adsorption of surfactants/polymers in enhanced oil recovery. Emphasis will be on the type and nature of different minerals in the oil reservoirs. Macroscopic adsorption, precipitation, wettability and nanoscopic orientation/conformation studies for aggregates of various surfactant/polymer mixtures on reservoir rocks systems is planned for exploring the cause of chemical loss by means of precipitation or adsorption, and the effect of rock mineralogy on the chemical loss. During this reporting period, the minerals proposed in this study: sandstone, limestone, gypsum, kaolinite and pyrite, have been characterized to obtain their particle size distribution and surface area, which will be used in the analysis of adsorption and wettability data. The effect of surfactant mixing ratio on the adsorption of mixture of C{sub 12}-C{sub 4}-C{sub 12} Gemini surfactant (synthesized during last period) and sugar-based nonionic surfactant n-dodecyl-{beta}-D-maltoside (DM) has been studied. It was discovered that even trace amounts of Gemini in the mixture is sufficient to force significant adsorption of DM. DM adsorption on silica increased from relatively negligible levels to very high levels. It is clear form analysis of the results that desired adsorption of either surfactant component in the mixtures can be obtained by controlling the mixing ratio, the total mixture concentration, pH etc. Along with these adsorption studies, changes in mineral wettability due to the adsorption of Gemini/DM mixtures were determined under relevant conditions to identify the nano-structure of the adsorbed layers. With increasing total surfactant adsorption, the silica mineral

  9. Counterion-mediated protein adsorption into polyelectrolyte brushes.

    PubMed

    He, Su-Zhen; Merlitz, Holger; Sommer, Jens-Uwe; Wu, Chen-Xu

    2015-09-01

    We present molecular dynamics simulations of the interaction of fullerene-like, inhomogeneously charged proteins with polyelectrolyte brushes. A motivation of this work is the experimental observation that proteins, carrying an integral charge, may enter like-charged polymer brushes. Simulations of varying charge distributions on the protein surfaces are performed to unravel the physical mechanism of the adsorption. Our results prove that an overall neutral protein can be strongly driven into polyelectrolyte brush whenever the protein features patches of positive and negative charge. The findings reported here give further evidence that the strong adsorption of proteins is also driven by entropic forces due to counterion release, since charged patches on the surface of the proteins can act as multivalent counterions of the oppositely charged polyelectrolyte chains. A corresponding number of mobile co- and counterions is released from the brush and the vicinity of the proteins so that the entropy of the total system increases. PMID:26385737

  10. Visualization and Measurement of Adsorption/Desorption Process of Ethanol in Activated Carbon Adsorber

    NASA Astrophysics Data System (ADS)

    Asano, Hitoshi; Murata, Kenta; Takenaka, Nobuyuki; Saito, Yasushi

    Adsorption refrigerator is one of the efficient tools for waste heat recovery, because the system is driven by heat at relative low temperature. However, the coefficient of performance is low due to its batch operation and the heat capacity of the adsorber. In order to improve the performance, it is important to optimize the configuration to minimize the amount of driving heat, and to clarify adsorption/desorption phenomena in transient conditions. Neutron radiography was applied to visualize and measure the adsorption amount distribution in an adsorber. The visualization experiments had been performed at the neutron radiography facility of E-2 port of Kyoto University Research Reactor. Activated carbon and ethanol were used as the adsorbent and refrigerant. From the acquired radiographs, adsorption amount was quantitatively measured by applying the umbra method using a checkered neutron absorber with boron powder. Then, transient adsorption and desorption processes of a rectangular adsorber with 84 mm in width, 50 mm in height and 20 mm in depth were visualized. As the result, the effect of fins in the adsorbent layer on the adsorption amount distribution was clearly visualized.

  11. Removal of cesium ions from aqueous solution by adsorption onto local Taiwan laterite.

    PubMed

    Wang, Tsing-Hai; Li, Ming-Hsu; Yeh, Wen-Chun; Wei, Yuan-Yaw; Teng, Shi-Ping

    2008-12-30

    Utilization of local Taiwan laterite (LTL) to remove aqueous cesium was investigated in this work under the conditions of various contact time, cesium (Cs) loading and temperature. Experimental results show that adsorption is instantaneous. Freundlich and Langmuir simulation results demonstrate that local Taiwan laterite has high affinity and sorption capacity for Cs at low temperatures, which may be attributed to enhanced desorption as temperature increased. Thermodynamic parameters including DeltaH, DeltaG and DeltaS were calculated and it is indicated that Cs adsorption on LTL is an exothermic, spontaneous and physical adsorption reaction. Moreover, the adsorbed Cs is distributed evenly on the LTL surface, which is confirmed by SEM/EDS mapping images. Furthermore, the absence of apparent shifting or broadening of the kaolinite signal in XRD patterns after Cs adsorption is an indication of the non-expanding characteristic of kaolinite structure. PMID:18448244

  12. Grand canonical Monte Carlo simulation of the adsorption isotherms of water molecules on model soot particles

    NASA Astrophysics Data System (ADS)

    Moulin, F.; Picaud, S.; Hoang, P. N. M.; Jedlovszky, P.

    2007-10-01

    The grand canonical Monte Carlo method is used to simulate the adsorption isotherms of water molecules on different types of model soot particles. The soot particles are modeled by graphite-type layers arranged in an onionlike structure that contains randomly distributed hydrophilic sites, such as OH and COOH groups. The calculated water adsorption isotherm at 298K exhibits different characteristic shapes depending both on the type and the location of the hydrophilic sites and also on the size of the pores inside the soot particle. The different shapes of the adsorption isotherms result from different ways of water aggregation in or/and around the soot particle. The present results show the very weak influence of the OH sites on the water adsorption process when compared to the COOH sites. The results of these simulations can help in interpreting the experimental isotherms of water adsorbed on aircraft soot.

  13. Thermodynamic and kinetic behaviors of trinitrotoluene adsorption on powdered activated carbons

    SciTech Connect

    Lee, J.W.; Hwang, K.J.; Shim, W.G.; Moon, I.S.

    2006-07-01

    Regulations on the removal of trinitrotoluene (TNT) from wastewater have become increasingly more stringent, demanding faster, less expensive, and more efficient treatment. This study focuses on the adsorption equilibrium and kinetics of TNT on powered activated carbons (PAC). Three types of PACs (i.e., wood based, coal based, and coconut-shell based) were studied as functions of temperature and pH. Thermodynamic properties including Gibbs free energy, enthalpy, and entropy, were evaluated by applying the Van't Hoff equation. In addition, the adsorption energy distribution functions which describe heterogeneous characteristics of porous solid sorbents were calculated by using the generalized nonlinear regularization method. Adsorption kinetic studies were carried out in batch adsorber under important conditions such as PAC types, temperature, pH, and concentration. We found that fast and efficient removal of TNT dissolved in water can be successfully achieved by PAC adsorption.

  14. Adsorption of heterobifunctional 4-nitrophenol on the Ge(100)-2 × 1 surface

    NASA Astrophysics Data System (ADS)

    Shong, Bonggeun; Hellstern, Thomas R.; Bent, Stacey F.

    2016-08-01

    We report the adsorption chemistry of a heterobifunctional molecule, 4-nitrophenol, on the Ge(100)-2 × 1 surface. X-ray photoelectron and infrared spectroscopy experiments and density functional theory calculations were used to determine the adsorption products. The results show that 4-nitrophenol reacts with the Ge surface through either one or both of the sbnd OH or sbnd NO2 functionalities. It was found that the fraction of dually and singly tethered adsorbates varies according to reaction conditions: namely, singly tethered adsorbates are favored at higher adsorbate coverages and lower adsorption temperatures. These variations are explained by a two-step adsorption mechanism for 4-nitrophenol, in which geometrical limitations of the adsorbates on the surface affect the product distribution.

  15. Metabolism of trichloroethylene.

    PubMed Central

    Lash, L H; Fisher, J W; Lipscomb, J C; Parker, J C

    2000-01-01

    A major focus in the study of metabolism and disposition of trichloroethylene (TCE) is to identify metabolites that can be used reliably to assess flux through the various pathways of TCE metabolism and to identify those metabolites that are causally associated with toxic responses. Another important issue involves delineation of sex- and species-dependent differences in biotransformation pathways. Defining these differences can play an important role in the utility of laboratory animal data for understanding the pharmacokinetics and pharmacodynamics of TCE in humans. Sex-, species-, and strain-dependent differences in absorption and distribution of TCE may play some role in explaining differences in metabolism and susceptibility to toxicity from TCE exposure. The majority of differences in susceptibility, however, are likely due to sex-, species-, and strain-dependent differences in activities of the various enzymes that can metabolize TCE and its subsequent metabolites. An additional factor that plays a role in human health risk assessment for TCE is the high degree of variability in the activity of certain enzymes. TCE undergoes metabolism by two major pathways, cytochrome P450 (P450)-dependent oxidation and conjugation with glutathione (GSH). Key P450-derived metabolites of TCE that have been associated with specific target organs, such as the liver and lungs, include chloral hydrate, trichloroacetate, and dichloroacetate. Metabolites derived from the GSH conjugate of TCE, in contrast, have been associated with the kidney as a target organ. Specifically, metabolism of the cysteine conjugate of TCE by the cysteine conjugate ss-lyase generates a reactive metabolite that is nephrotoxic and may be nephrocarcinogenic. Although the P450 pathway is a higher activity and higher affinity pathway than the GSH conjugation pathway, one should not automatically conclude that the latter pathway is only important at very high doses. A synthesis of this information is then

  16. Surfactant adsorption to soil components and soils.

    PubMed

    Ishiguro, Munehide; Koopal, Luuk K

    2016-05-01

    Soils are complex and widely varying mixtures of organic matter and inorganic materials; adsorption of surfactants to soils is therefore related to the soil composition. We first discuss the properties of surfactants, including the critical micelle concentration (CMC) and surfactant adsorption on water/air interfaces, the latter gives an impression of surfactant adsorption to a hydrophobic surface and illustrates the importance of the CMC for the adsorption process. Then attention is paid to the most important types of soil particles: humic and fulvic acids, silica, metal oxides and layered aluminosilicates. Information is provided on their structure, surface properties and primary (proton) charge characteristics, which are all important for surfactant binding. Subsequently, the adsorption of different types of surfactants on these individual soil components is discussed in detail, based on mainly experimental results and considering the specific (chemical) and electrostatic interactions, with hydrophobic attraction as an important component of the specific interactions. Adsorption models that can describe the features semi-quantitatively are briefly discussed. In the last part of the paper some trends of surfactant adsorption on soils are briefly discussed together with some complications that may occur and finally the consequences of surfactant adsorption for soil colloidal stability and permeability are considered. When we seek to understand the fate of surfactants in soil and aqueous environments, the hydrophobicity and charge density of the soil or soil particles, must be considered together with the structure, hydrophobicity and charge of the surfactants, because these factors affect the adsorption. The pH and ionic strength are important parameters with respect to the charge density of the particles. As surfactant adsorption influences soil structure and permeability, insight in surfactant adsorption to soil particles is useful for good soil management. PMID

  17. Hydrogen adsorption on functionalized nanoporous activated carbons.

    PubMed

    Zhao, X B; Xiao, B; Fletcher, A J; Thomas, K M

    2005-05-12

    There is considerable interest in hydrogen adsorption on carbon nanotubes and porous carbons as a method of storage for transport and related energy applications. This investigation has involved a systematic investigation of the role of functional groups and porous structure characteristics in determining the hydrogen adsorption characteristics of porous carbons. Suites of carbons were prepared with a wide range of nitrogen and oxygen contents and types of functional groups to investigate their effect on hydrogen adsorption. The porous structures of the carbons were characterized by nitrogen (77 K) and carbon dioxide (273 K) adsorption methods. Hydrogen adsorption isotherms were studied at 77 K and pressure up to 100 kPa. All the isotherms were Type I in the IUPAC classification scheme. Hydrogen isobars indicated that the adsorption of hydrogen is very temperature dependent with little or no hydrogen adsorption above 195 K. The isosteric enthalpies of adsorption at zero surface coverage were obtained using a virial equation, while the values at various surface coverages were obtained from the van't Hoff isochore. The values were in the range 3.9-5.2 kJ mol(-1) for the carbons studied. The thermodynamics of the adsorption process are discussed in relation to temperature limitations for hydrogen storage applications. The maximum amounts of hydrogen adsorbed correlated with the micropore volume obtained from extrapolation of the Dubinin-Radushkevich equation for carbon dioxide adsorption. Functional groups have a small detrimental effect on hydrogen adsorption, and this is related to decreased adsorbate-adsorbent and increased adsorbate-adsorbate interactions. PMID:16852056

  18. Surface structural ion adsorption modeling of competitive binding of oxyanions by metal (hydr)oxides

    SciTech Connect

    Hiemstra, T.; Riemsdijk, W.H. van

    1999-02-01

    An important challenge in surface complexation models (SCM) is to connect the molecular microscopic reality to macroscopic adsorption phenomena. This study elucidates the primary factor controlling the adsorption process by analyzing the adsorption and competition of PO{sub 4}, AsO{sub 4}, and SeO{sub 3}. The authors show that the structure of the surface-complex acting in the dominant electrostatic field can be ascertained as the primary controlling adsorption factor. The surface species of arsenate are identical with those of phosphate and the adsorption behavior is very similar. On the basis of the selenite adsorption, The authors show that the commonly used 1pK models are incapable to incorporate in the adsorption modeling the correct bidentate binding mechanism found by spectroscopy. The use of the bidentate mechanism leads to a proton-oxyanion ratio and corresponding pH dependence that are too large. The inappropriate intrinsic charge attribution to the primary surface groups and the condensation of the inner sphere surface complex to a point charge are responsible for this behavior of commonly used 2pK models. Both key factors are differently defined in the charge distributed multi-site complexation (CD-MUSIC) model and are based in this model on a surface structural approach. The CD-MUSIC model can successfully describe the macroscopic adsorption phenomena using the surface speciation and binding mechanisms as found by spectroscopy. The model is also able to predict the anion competition well. The charge distribution in the interface is in agreement with the observed structure of surface complexes.

  19. Multifractal characteristics of Nitrogen adsorption isotherms from tropical soils

    NASA Astrophysics Data System (ADS)

    Vidal Vázquez, Eva; Paz Ferreiro, Jorge

    2010-05-01

    One of the primary methods used to characterize a wide range of porous materials, including soils, are gas adsorption isotherms. An adsorption isotherm is a function relating the amount of adsorbed gas or vapour to the respective equilibrium pressure, during pressure increase at constant temperature. Adsorption data allow easily estimates of specific surface area and also can provide a characterization of pore surface heterogeneity. Most of the properties and the reactivity of soil colloids are influenced by their specific surface area and by parameters describing the surface heterogeneity. For a restricted scale range, linearity between applied pressure and volume of adsorbate holds, which is the basis for current estimations of specific surface area. However, adsorption isotherms contain also non-linear segments of pressure versus volume so that evidence of multifractal scale has been demonstrated. The aim of this study was to analyze the multifractal behaviour of nitrogen adsorption isotherms from a set of tropical soils. Samples were collected form 54 horizons belonging to 19 soil profiles in the state of Minas Gerais, Brazil. The most frequent soil type was Oxisol, according to the Soil Survey Staff, equivalent to Latossolo in the Brazilian soil classification system. Nitrogen adsorption isotherms at standard 77 K were measured using a Thermo Finnigan Sorptomatic 1990 gas sorption analyzer (Thermo Scientific, Waltham, MA). From the raw data a distributions of mass along a support was obtained to perform multifractal analysis. The probability distribution was constructed by dividing the values of the measure in a given segment by the sum of the measure in the whole scale range. The box-counting method was employed to perform multifractal analysis. All the analyzed N2 adsorption isotherms behave like a multifractal system. The singularity spectra, f(α), showed asymmetric concave down parabolic shapes, with a greater tendency toward the left side, where moments

  20. Application of Vacuum Swing Adsorption for Carbon Dioxide and Water Vapor Removal from Manned Spacecraft Atmospheres

    NASA Technical Reports Server (NTRS)

    Knox, J.; Fulda, P.; Howard, D.; Ritter, J.; Levan, M.

    2007-01-01

    The design and testing of a vacuum-swing adsorption process to remove metabolic 'water and carbon dioxide gases from NASA's Orion crew exploration vehicle atmosphere is presented. For the Orion spacecraft, the sorbent-based atmosphere revitalization (SBAR) system must remove all metabolic water, a technology approach 1Lhathas not been used in previous spacecraft life support systems. Design and testing of a prototype SBAR in sub-scale and full-scale configurations is discussed. Experimental and analytical investigations of dual-ended and single-ended vacuum desorption are presented. An experimental investigation of thermal linking between adsorbing and desorbing columns is also presented.

  1. Phenolic resin-based porous carbons for adsorption and energy storage applications

    NASA Astrophysics Data System (ADS)

    Wickramaratne, Nilantha P.

    The main objective of this dissertation research is to develop phenolic resin based carbon materials for range of applications by soft-templating and Stober-like synthesis strategies. Applications Studied in this dissertation are adsorption of CO2, bio-molecular and heavy metal ions, and energy storage devices. Based on that, our goal is to design carbon materials with desired pore structure, high surface area, graphitic domains, incorporated metal nanoparticles, and specific organic groups and heteroatoms. In this dissertation the organic-organic self-assembly of phenolic resins and triblock copolymers under acidic conditions will be used to obtain mesoporous carbons/carbon composites and Stober-like synthesis involving phenolic resins under basic condition will be used to prepare polymer/carbon particles and their composites. The structure of this dissertation consists of an introductory chapter (Chapter 1) discussing the general synthesis of carbon materials, particularly the soft-templating strategy and Stober-like carbon synthesis. Also, Chapter 1 includes a brief outline of applications namely adsorption of CO2, biomolecule and heavy metal ions, and supercapacitors. Chapter 2 discusses the techniques used for characterization of the carbon materials studied. This chapter starts with nitrogen adsorption analysis, which is used to measure the specific surface area, pore volume, distribution of pore sizes, and pore width. In addition to nitrogen adsorption, powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution thermogravimetric analysis (HR-TGA), cyclic voltammetry (CV) and CHNS elemental analysis (EA) are mentioned too. Chapter 3 is focused on carbon materials for CO2 adsorption. There are different types of porous solid materials such as silicate, MOFs, carbons, and zeolites studied for CO2 adsorption. However, the carbon based materials are considered to be the best candidates for CO 2 adsorption to the industrial point of

  2. Inositol Metabolism in Plants

    PubMed Central

    Kroh, M.; Miki-Hirosige, H.; Rosen, W.; Loewus, F.

    1970-01-01

    When detached flowers or isolated pistils of Lilium longiflorum are given myoinositol-U-14C or -2-3H as dilute solution through the severed pedicel, label is quickly distributed by the vascular system. In the case of pistils, a pattern of labeling in ovary, style, and stigma is obtained which indicates that products of myoinositol metabolism are utilized in the biosynthesis of exudate (secretion product) of the stigma and style as well as for components of pistil cell walls. Pollination had no discernible effect on labeling pattern. Images PMID:5436329

  3. Arsenate adsorption by unsaturated alluvial sediments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Arsenate adsorption as a function of solution arsenic concentration and solution pH was investigated on five alluvial sediments from the Antelope Valley, Western Mojave Desert, California. Arsenate adsorption increased with increasing solution pH, exhibited a maximum around pH 4 to 5, and then decr...

  4. Size dependent adsorption on nanocrystal surfaces

    NASA Astrophysics Data System (ADS)

    Lu, H. M.; Wen, Z.; Jiang, Q.

    2005-03-01

    A quantitative thermodynamic correlation method to describe the size dependent Langmuir adsorption isotherm is developed. According to the model, the equilibrium adsorption constant increases as material size decreases, which is in agreement with the literature data of acetic acid, valeric acid, oxalic acid, and adipic acid on anatase nanoparticles.

  5. Ion Exchange and Adsorption of Inorganic Contaminants

    EPA Science Inventory

    In the first part of the chapter, the fundamentals of ion exchange and adsorption processes are explained, with the goal of demonstrating how these principles influence process design for inorganic contaminant removal. In the second part, ion exchange and adsorption processes th...

  6. Adsorption of pyridine by combusted oil shale

    NASA Astrophysics Data System (ADS)

    Essington, M. E.

    1992-03-01

    Large volumes of solid waste material will be produced during the commercial production of shale oil. An alternative to the disposal of the solid waste product is utilization. One potential use of spent oil shale is for the stabilization of hazardous organic compounds. The objective of this study was to examine the adsorption of pyridine, commonly found in oil shale process water, by spent oil shale. The adsorption of pyridine by fresh and weathered samples of combusted New Albany Shale and Green River Formation oil shale was examined. In general, pyridine adsorption can be classified as L-type and the isotherms modeled with the Langmuir and Freundlich equations. For the combusted New Albany Shale, weathering reduced the predicted pyridine adsorption maximum and increased the amount of pyridine adsorbed at low solution concentrations. For the combusted Green River Formation oil shales, weathering increased the predicted pyridine adsorption maximum. The pyridine adsorption isotherms were similar to those produced for a combusted Australian oil shale. Although adsorption can be mathematically described by empirical models, the reduction in solution concentrations of pyridine was generally less than 10 mg/l at an initial concentration of 100 mg/l. Clearly, the observed reduction in solution pyridine concentrations does not sufficiently justify using spent oil shale as a stabilizing medium. However, data in the literature suggest that other organic compounds can be effectively removed from solution by spent oil shale and that adsorption is dependent on process conditions and organic compound type.

  7. Effect of lipid composition and packing on the adsorption of apolipoproteins to lipid monolayers

    SciTech Connect

    Ibdah, J.A.; Lund-Katz, S.; Phillips, M.C.

    1987-05-01

    The monolayer system has been used to study the effects of lipoprotein surface lipid composition and packing on the affinities of apolipoproteins for the surfaces of lipoprotein particles. The adsorption of apolipoproteins injected beneath lipid monolayers prepared with pure lipids or lipoprotein surface lipids is evaluated by monitoring the surface pressure of the film and the surface concentration (Gamma) of /sup 14/C-labelled apolipoprotein. At a given initial film pressure (..pi../sub i/) there is a higher adsorption of human apo A-I to unsaturated phosphatidylcholine (PC) monolayers compared to saturated PC monolayers (e.g., at ..pi../sub i/ = 10 mN/m, Gamma = 0.35 and 0.06 mg/m/sup 2/ for egg PC and distearoyl PC, respectively, with 3 x 10/sup -4/ mg/ml apo A-I in the subphase). In addition, adsorption of apo A-I is less to an egg sphingomyelin monolayer than to an egg PC monolayer. The adsorption of apo A-I to PC monolayers is decreased by addition of cholesterol. Generally, apo A-I adsorption diminishes as the lipid molecular area decreases. Apo A-I adsorbs more to monolayers prepared with HDL/sub 3/ surface lipids than with LDL surface lipids. These studies suggest that lipoprotein surface lipid composition and packing are crucial factors influencing the transfer and exchange of apolipoproteins among various lipoprotein classes during metabolism of lipoprotein particles.

  8. A Tire-Sulfur Hybrid Adsorption Denitrification (T-SHAD) process for decentralized wastewater treatment.

    PubMed

    Krayzelova, Lucie; Lynn, Thomas J; Banihani, Qais; Bartacek, Jan; Jenicek, Pavel; Ergas, Sarina J

    2014-09-15

    Nitrogen discharges from decentralized wastewater treatment (DWT) systems contribute to surface and groundwater contamination. However, the high variability in loading rates, long idle periods and lack of regular maintenance presents a challenge for biological nitrogen removal in DWT. A Tire-Sulfur Hybrid Adsorption Denitrification (T-SHAD) process was developed that combines nitrate (NO3(-)) adsorption to scrap tire chips with sulfur-oxidizing denitrification. This allows the tire chips to adsorb NO3(-) when the influent loading exceeds the denitrification capacity of the biofilm and release it when NO3(-) loading rates are low (e.g. at night). Three waste products, scrap tire chips, elemental sulfur pellets and crushed oyster shells, were used as a medium in adsorption, leaching, microcosm and up-flow packed bed bioreactor studies of NO3(-) removal from synthetic nitrified DWT wastewater. Adsorption isotherms showed that scrap tire chips have an adsorption capacity of 0.66 g NO3(-)-N kg(-1) of scrap tires. Leaching and microcosm studies showed that scrap tires leach bioavailable organic carbon that can support mixotrophic metabolism, resulting in lower effluent SO4(2-) concentrations than sulfur oxidizing denitrification alone. In column studies, the T-SHAD process achieved high NO3(-)-N removal efficiencies under steady state (90%), variable flow (89%) and variable concentration (94%) conditions. PMID:24922353

  9. Genome-wide Distribution of AdpA, a Global Regulator for Secondary Metabolism and Morphological Differentiation in Streptomyces, Revealed the Extent and Complexity of the AdpA Regulatory Network

    PubMed Central

    Higo, Akiyoshi; Hara, Hirofumi; Horinouchi, Sueharu; Ohnishi, Yasuo

    2012-01-01

    AdpA is a global transcriptional activator triggering morphological differentiation and secondary metabolism in Streptomyces griseus. AdpA influences the expression of >1000 genes; however, the overall picture of the AdpA regulon remains obscure. Here, we took snapshots of the distribution of AdpA across the chromosome in living S. griseus cells using chromatin immunoprecipitation/chromatin affinity precipitation-seq analysis. In both liquid and solid cultures, AdpA bound to >1200 similar sites, which were located on not only in putative regulatory regions (65%), but also in regions (35%) that appeared not to affect transcription. Transcriptome analysis indicated that ∼40% of the AdpA-binding sites in putative regulatory regions were involved in gene regulation. AdpA was indicated to act as a transcriptional repressor as well as an activator. Expression profiles of AdpA-target genes were very different between liquid and solid cultures, despite their similar AdpA-binding profiles. We concluded that AdpA directly controls >500 genes in cooperation with other regulatory proteins. A comprehensive competitive gel mobility shift assay of AdpA with 304 selected AdpA-binding sites revealed several unique characteristics of the DNA-binding property of AdpA. This study provides the first experimental insight into the extent of the AdpA regulon, indicating that many genes are under the direct control of AdpA. PMID:22449632

  10. Ca2+ Binding/Permeation via Calcium Channel, CaV1.1, Regulates the Intracellular Distribution of the Fatty Acid Transport Protein, CD36, and Fatty Acid Metabolism.

    PubMed

    Georgiou, Dimitra K; Dagnino-Acosta, Adan; Lee, Chang Seok; Griffin, Deric M; Wang, Hui; Lagor, William R; Pautler, Robia G; Dirksen, Robert T; Hamilton, Susan L

    2015-09-25

    Ca(2+) permeation and/or binding to the skeletal muscle L-type Ca(2+) channel (CaV1.1) facilitates activation of Ca(2+)/calmodulin kinase type II (CaMKII) and Ca(2+) store refilling to reduce muscle fatigue and atrophy (Lee, C. S., Dagnino-Acosta, A., Yarotskyy, V., Hanna, A., Lyfenko, A., Knoblauch, M., Georgiou, D. K., Poché, R. A., Swank, M. W., Long, C., Ismailov, I. I., Lanner, J., Tran, T., Dong, K., Rodney, G. G., Dickinson, M. E., Beeton, C., Zhang, P., Dirksen, R. T., and Hamilton, S. L. (2015) Skelet. Muscle 5, 4). Mice with a mutation (E1014K) in the Cacna1s (α1 subunit of CaV1.1) gene that abolishes Ca(2+) binding within the CaV1.1 pore gain more body weight and fat on a chow diet than control mice, without changes in food intake or activity, suggesting that CaV1.1-mediated CaMKII activation impacts muscle energy expenditure. We delineate a pathway (Cav1.1→ CaMKII→ NOS) in normal skeletal muscle that regulates the intracellular distribution of the fatty acid transport protein, CD36, altering fatty acid metabolism. The consequences of blocking this pathway are decreased mitochondrial β-oxidation and decreased energy expenditure. This study delineates a previously uncharacterized CaV1.1-mediated pathway that regulates energy utilization in skeletal muscle. PMID:26245899

  11. Development of facile property calculation model for adsorption chillers based on equilibrium adsorption cycle

    NASA Astrophysics Data System (ADS)

    Yano, Masato; Hirose, Kenji; Yoshikawa, Minoru; Thermal management technology Team

    Facile property calculation model for adsorption chillers was developed based on equilibrium adsorption cycles. Adsorption chillers are one of promising systems that can use heat energy efficiently because adsorption chillers can generate cooling energy using relatively low temperature heat energy. Properties of adsorption chillers are determined by heat source temperatures, adsorption/desorption properties of adsorbent, and kinetics such as heat transfer rate and adsorption/desorption rate etc. In our model, dependence of adsorption chiller properties on heat source temperatures was represented using approximated equilibrium adsorption cycles instead of solving conventional time-dependent differential equations for temperature changes. In addition to equilibrium cycle calculations, we calculated time constants for temperature changes as functions of heat source temperatures, which represent differences between equilibrium cycles and real cycles that stemmed from kinetic adsorption processes. We found that the present approximated equilibrium model could calculate properties of adsorption chillers (driving energies, cooling energies, and COP etc.) under various driving conditions quickly and accurately within average errors of 6% compared to experimental data.

  12. Argon Adsorption on Open Carbon Nanohorns

    NASA Astrophysics Data System (ADS)

    Russell, Brice; Calvillo, Angel; Khanal, Pravin; Migone, Aldo; Iijima, Sumio; Yudasaka, Masako

    We have measured adsorption isotherms for argon adsorbed on a 0.1692 g sample of chemically-opened carbon nanohorns. Two clear substeps are visible in the adsorption data, corresponding to groups of stronger binding sites (lower pressure substep) and weaker binding sites (higher pressure substep). We have measured adsorption at eight different temperatures in the range between approximately 70 and 110 K. The space at the interior of the individual nanohorns is accessible to sorbates in these chemically opened nanohorns. Consequently, higher loadings are obtained on these samples when compared to those measured on unopened (as-produced) nanohorns. Results for the kinetics of adsorption, the effective specific surface area, and the isosteric heat of adsorption as a function of sorbent loading will be presented and compared to results from other gases adsorbed on nanohorns. This work was supported by the NSF through Grant DMR-1006428.

  13. Adsorption of xenon and krypton on shales

    NASA Technical Reports Server (NTRS)

    Podosek, F. A.; Bernatowicz, T. J.; Kramer, F. E.

    1981-01-01

    A method that uses a mass spectrometer as a manometer is employed in the measurement of Xe and Kr adsorption parameters on shales and related samples, where gas partial pressures were lower than 10 to the -11th atm, corresponding adsorption coverages are only small fractions of a monolayer, and Henry's Law behavior is expected and observed. Results show heats of adsorption in the 2-7 kcal/mol range, and Henry constants at 0-25 C of 1 cu cm STP/g per atmosphere are extrapolated. Although the adsorption properties obtained are variable by sample, the range obtained suggests that shales may be capable of an equilibrium adsorption with modern air high enough to account for a significant fraction of the atmospheric inventory of Xe, and perhaps even of Kr. This effect will nevertheless not account for the factor-of-25 defficiency of atmospheric Xe, in comparison with the planetary gas patterns observed in meteorites.

  14. Selective adsorption for removal of nitrogen compounds from hydrocarbon streams over carbon-based adsorbents

    NASA Astrophysics Data System (ADS)

    Almarri, Masoud S.

    The ultimate goal of this thesis is to develop a fundamental understanding of the role of surface oxygen functional groups on carbon-based adsorbents in the adsorption of nitrogen compounds that are known to be present in liquid fuels. N2 adsorption was used to characterize pore structures. The surface chemical properties of the adsorbents were characterized by X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD) techniques with a mass spectrometer to identify and quantify the type and concentration of oxygen functional groups on the basis of CO2 and CO evolution profiles. It was found that although surface area and pore size distribution are important for the adsorption process, they are not primary factors in the adsorption of nitrogen compounds. On the other hand, both the type and concentration of surface oxygen-containing functional groups play an important role in determining adsorptive denitrogenation performance. Higher concentrations of the oxygen functional groups on the adsorbents resulted in a higher adsorption capacity for the nitrogen compounds. A fundamental insight was gained into the contributions of different oxygen functional groups by analyzing the changes in the monolayer maximum adsorption capacity, qm, and the adsorption constant, K, for nitrogen compounds on different activated carbons. Acidic functional groups such as carboxylic acids and carboxylic anhydrides appear to contribute more to the adsorption of quinoline, while the basic oxygen functional groups such as carbonyls and quinones enhance the adsorption of indole. Despite the high number of publications on the adsorptive desulfurization of liquid hydrocarbon fuels, these studies did not consider the presence of coexisting nitrogen compounds. It is well-known that, to achieve ultraclean diesel fuel, sulfur must be reduced to a very low level, where the concentrations of nitrogen and sulfur compounds are comparable. The adsorptive denitrogenation and

  15. Heterogeneous adsorption and catalytic oxidation of benzene, toluene and xylene over spent and chemically regenerated platinum catalyst supported on activated carbon

    NASA Astrophysics Data System (ADS)

    Shim, Wang Geun; Kim, Sang Chai

    2010-06-01

    The heterogeneous adsorption and catalytic oxidation of benzene, toluene and o-xylene (BTX) over the spent platinum catalyst supported on activated carbon (Pt/AC) as well as the chemically treated spent catalysts were studied to understand their catalytic and adsorption activities. Sulfuric aqueous acid solution (0.1N, H 2SO 4) was used to regenerate the spent Pt/AC catalyst. The physico-chemical properties of the catalysts in the spent and chemically treated states were analyzed by using nitrogen adsorption-desorption isotherm and elemental analysis (EDX). The gravimetric adsorption and the light-off curve analysis were employed to study the BTX adsorption and oxidation on the spent catalyst and its modified Pt/AC catalysts. The experimental results indicate that the spent Pt/AC catalyst treated with the H 2SO 4 aqueous solution has a higher toluene adsorption and conversion ability than that of the spent Pt/AC catalyst. A further studies of H 2SO 4 treated Pt/AC catalyst on their catalytic and heterogeneous adsorption behaviours for BTX revealed that the activity of the H 2SO 4 treated Pt/AC catalyst follows the sequence of benzene > toluene > o-xylene. The adsorption equilibrium isotherms of BTX on the H 2SO 4 treated Pt/AC were measured at different temperatures ranging from 120 to 180 °C. To correlate the equilibrium data and evaluate their adsorption affinity for BTX, the two sites localized Langmuir (L2m) isotherm model was employed. The heterogeneous surface feature of the H 2SO 4 treated Pt/AC was described in detail with the information obtained from the results of isosteric enthalpy of adsorption and adsorption energy distributions. Furthermore, the activity of H 2SO 4 treated Pt/AC about BTX was found to be directly related to the Henry's constant, isosteric enthalpy of adsorption and adsorption energy distribution functions.

  16. Human fibrinogen adsorption on positively charged latex particles.

    PubMed

    Zeliszewska, Paulina; Bratek-Skicki, Anna; Adamczyk, Zbigniew; Cieśla, Michał

    2014-09-23

    Fibrinogen (Fb) adsorption on positively charged latex particles (average diameter of 800 nm) was studied using the microelectrophoretic and the concentration depletion methods based on AFM imaging. Monolayers on latex were adsorbed from diluted bulk solutions at pH 7.4 and an ionic strength in the range of 10(-3) to 0.15 M where fibrinogen molecules exhibited an average negative charge. The electrophoretic mobility of the latex after controlled fibrinogen adsorption was systematically measured. A monotonic decrease in the electrophoretic mobility of fibrinogen-covered latex was observed for all ionic strengths. The results of these experiments were interpreted according to the three-dimensional electrokinetic model. It was also determined using the concentration depletion method that fibrinogen adsorption was irreversible and the maximum coverage was equal to 0.6 mg m(-2) for ionic strength 10(-3) M and 1.3 mg m(-2) for ionic strength 0.15 M. The increase of the maximum coverage was confirmed by theoretical modeling based on the random sequential adsorption approach. Paradoxically, the maximum coverage of fibrinogen on positively charged latex particles was more than two times lower than the maximum coverage obtained for negative latex particles (3.2 mg m(-2)) at pH 7.4 and ionic strength of 0.15 M. This was interpreted as a result of the side-on adsorption of fibrinogen molecules with their negatively charged core attached to the positively charged latex surface. The stability and acid base properties of fibrinogen monolayers on latex were also determined in pH cycling experiments where it was observed that there were no irreversible conformational changes in the fibrinogen monolayers. Additionally, the zeta potential of monolayers was more positive than the zeta potential of fibrinogen in the bulk, which proves a heterogeneous charge distribution. These experimental data reveal a new, side-on adsorption mechanism of fibrinogen on positively charged surfaces and

  17. Theoretical study of heavy metal Cd, Cu, Hg, and Ni(II) adsorption on the kaolinite(0 0 1) surface

    NASA Astrophysics Data System (ADS)

    Zhao, Jian; He, Man-Chao

    2014-10-01

    Heavy metal pollution is currently of great concern because it has been recognized as a potential threat to air, water, and soil. Adsorption was one of the most popular methods for the removal of heavy metal. The adsorption of heavy metal Cd, Cu, Hg, and Ni(II) atoms on the hydroxylated (0 0 1) surface of kaolinite was investigated using density-functional theory within the generalized gradient approximation and a supercell approach. The coverage dependence of the adsorption structures and energetics were systematically studied for a wide range of coverage Θ [from 0.11 to 1.0 monolayers (ML)] and adsorption sites. The most stable among all possible adsorption sites for Cd(II) atom was the two-fold bridge site followed by the one-fold top site, and the top site was the most favorite adsorption site for Cu and Ni(II) atoms, while the three-fold hollow site was the most stable adsorption site for Hg(II) atom followed by the two-fold bridge site. The adsorption energy increases with the coverage for Cd, Cu, and Hg(II) atoms, thus indicating the higher stability of surface adsorption and a tendency to the formation of adsorbate islands (clusters) with increasing the coverage. However, the adsorption energy of Ni(II) atoms decreases when increasing the coverage. The adsorption capabilities of the kaolinite clay for the heavy metal atoms were in the order of Ni > Cu > Cd > Hg(II). The other properties of the Cd, Cu, Hg, and Ni(II)/kaolinite(0 0 1) system including the different charge distribution, the lattice relaxation, and the electronic density of states were also studied and discussed in detail.

  18. Reversible Adsorption Kinetics of Near Surface Dimer Colloids.

    PubMed

    Salipante, Paul F; Hudson, Steven D

    2016-08-30

    We investigate the effect of shape on reversible adsorption kinetics using colloidal polystyrene dimers near a solid glass surface as a model system. The interaction between colloid and wall is tuned using electrostatic, depletion, and gravity forces to produce a double-well potential. The dwell time in each of the potential wells is measured from long duration particle trajectories. The height of each monomer relative to the glass surface is measured to a resolution of <20 nm by in-line holographic microscopy. The measured transition probability distributions are used in kinetic equations to describe the flux of particles to and from the surface. The dimers are compared to independent isolated monomers to determine the effects of shape on adsorption equilibria and kinetics. To elucidate these differences, we consider both mass and surface coverage and two definitions of surface coverage. The results show that dimers with single coverage produce slower adsorption, lower surface coverage, and higher mass coverage in comparison to those of monomers, while dimers with double coverage adsorb faster and result in higher surface coverage. PMID:27483023

  19. Adsorption of SOx and NOx in activated viscose fibers.

    PubMed

    Plens, Ana Carolina O; Monaro, Daniel L G; Coutinho, Aparecido R

    2015-01-01

    SOx and NOx are emissions resulting from combustion processes and are the main agents that contribute to the formation of acid rain, which causes harm to humans and the environment. Several techniques for removing these pollutants are applied in i.e. oil refineries, thermoelectric that use petroleum oils and vehicular pollution. Among these, highlight the adsorption of contaminants by the usage of activated carbon fibers and activated carbon, which are characterized by high surface area and uniform distribution of pores, providing appropriate conditions for application in processes of removing environmental contaminants. In the present work, activated viscose fibers (AVF) were prepared and applied in adsorption experiments of NO and SO2. The materials produced showed high values of surface area, with a predominance of micro pores with diameters in the range of 1.0 nm. The AVF had satisfactory performance in the removal of contaminants and are compatible with other synthetic fibers. Thus, the formation of active sites of carbon provides contaminants adsorption, demonstrating that carbon fibers cloth can be applied for the removal of pollutants. PMID:25993357

  20. 2-Hydroxypropyltrimethylammonium xylan adsorption onto rod-like cellulose nanocrystal.

    PubMed

    Sim, Jae Hyun; Dong, Shuping; Röemhild, Katrin; Kaya, Abdulaziz; Sohn, Daewon; Tanaka, Keiji; Roman, Maren; Heinze, Thomas; Esker, Alan R

    2015-02-15

    Chemical incompatibility and relatively weak interaction between lignocellulosic fibers and synthetic polymers have made studies of wood fiber-thermoplastic composite more challenging. In this study, adsorption of 2-hydroxypropyltrimethylammonium xylans onto rod-like cellulose nanocrystals are investigated by zeta-potential measurements, and polarized and depolarized dynamic light scattering as a factor for better understanding of lignocellulosic fibers and cellulose nanocrystals. Zeta-potential measurements show xylan derivative adsorption onto cellulose nanocrystals. Decay time distributions of the ternary system and binary system from dynamic light scattering show that aggregates exist in the binary system and they disappear in the ternary system. At low 2-hydroxypropyltrimethylammonium xylan concentrations relative to that of cellulose nanocrystal, xylan derivatives adsorbed onto some of the cellulose nanocrystal. Hence, more xylan derivatives adsorbed onto cellulose nanocrystal increased with increasing xylan derivative concentration. Also, the concentration dependence of the ratio of the rotational diffusion coefficient to the translational diffusion coefficient revealed a strong adsorptive interaction between xylan derivatives and the cellulose nanocrystals. PMID:25460697

  1. Why Metabolic Syndrome Matters

    MedlinePlus

    ... Pressure Tools & Resources Stroke More Why Metabolic Syndrome Matters Updated:Jul 24,2014 Metabolic syndrome may be ... Syndrome • Home • About Metabolic Syndrome • Why Metabolic Syndrome Matters • Your Risk for Metabolic Syndrome • Symptoms & Diagnosis • Prevention & ...

  2. The role of particle-size soil fractions in the adsorption of heavy metals

    NASA Astrophysics Data System (ADS)

    Mandzhieva, Saglara; Minkina, Tatiana; Pinsky, David; Batukaev, Abdulmalik; Kalinitchenko, Valeriy; Sushkova, Svetlana; Chaplygin, Viktor; Dikaev, Zaurbek; Startsev, Viktor; Bakoev, Serojdin

    2014-05-01

    Ion-exchange adsorption phenomena are important in the immobilization of heavy metals (HMs) by soils. Numerous works are devoted to the study of this problem. However, the interaction features of different particle-size soil fractions and their role in the immobilization of HMs studied insufficiently. Therefore, the assessment of the effect of the particle-size distribution on the adsorption properties of soils is a vital task. The parameters of Cu2+, Pb2+ and Zn2+ adsorption by chernozems of the south of Russia and their particle-size fractions were studied. In the particle-size fractions separated from the soils, the concentrations of Cu2+, Pb2+, and Zn2 decreased with the decreasing particle size. The parameters of the adsorption values of k (the constant of the affinity)and Cmax.(the maximum adsorption of the HMs) characterizing the adsorption of HMs by the southern chernozem and its particle-size fractions formed the following sequence: silt > clay > entire soil. The adsorption capacity of chernozems for Cu2+, Pb2+, and Zn2+ depending on the particle-size distribution decreased in the following sequence: clay loamy ordinary chernozem clay loamy southern chernozem> loamy southern chernozem> loamy sandy southern chernozem. According to the parameters of the adsorption by the different particle-size fractions, the heavy metal cations form a sequence analogous to that obtained for the entire soils: Cu2+ ≥ Pb2+ > Zn2+. The parameters of the heavy metal adsorption by similar particle-size fractions separated from different soils decreased in the following order: clay loamy chernozem> loamy chernozem> loamy sandy chernozem. The analysis of the changes in the parameters of the Cu2+, Pb2+, and Zn2+ adsorption by the studied soils and their particle-size fractions showed that the extensive adsorption characteristic - the maximum adsorption (Cmax.) - is a less sensitive parameter characterizing the adsorption capacity of the soils than the intensive characteristic of

  3. Comparison of the adsorption mechanisms of pyridine in hydrophilic interaction chromatography and in reversed-phase aqueous liquid chromatography.

    PubMed

    Gritti, Fabrice; Pereira, Alberto dos Santos; Sandra, Pat; Guiochon, Georges

    2009-11-27

    The adsorption isotherms of pyridine were measured by frontal analysis (FA) on a column packed with shell particles of neat porous silica (Halo), using water-acetonitrile mixtures as the mobile phase at 295K. The isotherm data were measured for pyridine concentrations covering a dynamic range of four millions. The degree of heterogeneity of the surface was characterized by the adsorption energy distribution (AED) function calculated from the raw adsorption data, using the expectation-maximization (EM) procedure. The results showed that two different retention mechanisms dominate in Per aqueous liquid chromatography (PALC) at low acetonitrile concentrations and in hydrophilic interaction chromatography (HILIC) at high acetonitrile concentrations. In the PALC mode, the adsorption mechanism of pyridine on the silica surface is controlled by hydrophobic interactions that take place on very few and ultra-active adsorption sites, which might be pores on the irregular and rugose surface of the porous silica particles. The surface is seriously heterogeneous, with up to five distinct adsorption sites and five different energy peaks on the AED of the packing material. In contrast, in the HILIC mode, the adsorption behavior is quasi-homogeneous and pyridine retention is governed by its adsorption onto free silanol groups. For intermediate mobile phase compositions, the siloxane and the silanol groups are both significantly saturated with acetonitrile and water, respectively, causing a minimum of the retention factor of pyridine on the Halo column. PMID:19853257

  4. Effect of the ionic status and drying on radiocesium adsorption and desorption in organic soils

    SciTech Connect

    Rigol, A.; Vidal, M.; Rauret, G.

    1999-11-01

    Radiocesium (RCs) interaction in organic soils has been studied using adsorption and desorption experiments, and the effects of the ionic status and drying were evaluated. Four organic soils were used: three peaty podzols containing illite and a peat without illitic materials, RCs solid-liquid distribution coefficients (K{sub D}) were determined for each soil in water and in several solutions containing Ca, K, or a mixture of the two. RCs contamination was performed either with a single equilibration or after a three-step preequilibration. Whereas the ionic strength of the solution controlled RCs adsorption in the peat, the level of monovalent species was the most important factor in RCs adsorption in the peaty podzols. Reversibility of RCs adsorbed in the different conditions was assessed in the moist sample and after drying by single and consecutive extractions with either CaCl{sub 2} or CH{sub 3}COONH{sub 4}. RCs adsorption was totally reversible in the peat regardless of the ionic status and the desorption approach used. For the three peaty podzols, due to the presence of specific sites, adsorption reversibility was dependent on the scenario in which this adsorption was performed and on the cation used in desorption. Finally, although NH{sub 4} is known to desorb RCs specifically adsorbed in the soil, it was shown to induce interlayer collapse, and consecutive extractions with CaCl{sub 2} led to higher desorption yields.

  5. Polyelectrolyte adsorption onto like-charged surfaces mediated by trivalent counterions: a Monte Carlo simulation study.

    PubMed

    Luque-Caballero, Germán; Martín-Molina, Alberto; Quesada-Pérez, Manuel

    2014-05-01

    Both experiments and theory have evidenced that multivalent cations can mediate the interaction between negatively charged polyelectrolytes and like-charged objects, such as anionic lipoplexes (DNA-cation-anionic liposome complexes). In this paper, we use Monte Carlo simulations to study the electrostatic interaction responsible for the trivalent-counterion-mediated adsorption of polyelectrolytes onto a like-charged planar surface. The evaluation of the Helmholtz free energy allows us to characterize both the magnitude and the range of the interaction as a function of the polyelectrolyte charge, surface charge density, [3:1] electrolyte concentration, and cation size. Both polyelectrolyte and surface charge favor the adsorption. It should be stressed, however, that the adsorption will be negligible if the surface charge density does not exceed a threshold value. The effect of the [3:1] electrolyte concentration has also been analyzed. In certain range of concentrations, the counterion-mediated attraction seems to be independent of this parameter, whereas very high concentrations of salt weaken the adsorption. If the trivalent cation diameter is doubled the adsorption moderates due to the excluded volume effects. The analysis of the integrated charge density and ionic distributions suggests that a delicate balance between charge inversion and screening effects governs the polyelectrolyte adsorption onto like-charged surfaces mediated by trivalent cations. PMID:24811649

  6. Water adsorption at high temperature on core samples from The Geysers geothermal field

    SciTech Connect

    Gruszkiewicz, M.S.; Horita, J.; Simonson, J.M.; Mesmer, R.E.

    1998-06-01

    The quantity of water retained by rock samples taken from three wells located in The Geysers geothermal reservoir, California, was measured at 150, 200, and 250 C as a function of pressure in the range 0.00 {le} p/p{sub 0} {le} 0.98, where p{sub 0} is the saturated water vapor pressure. Both adsorption (increasing pressure) and desorption (decreasing pressure) runs were made in order to investigate the nature and the extent of the hysteresis. Additionally, low temperature gas adsorption analyses were performed on the same rock samples. Nitrogen or krypton adsorption and desorption isotherms at 77 K were used to obtain BET specific surface areas, pore volumes and their distributions with respect to pore sizes. Mercury intrusion porosimetry was also used to obtain similar information extending to very large pores (macropores). A qualitative correlation was found between the surface properties obtained from nitrogen adsorption and the mineralogical and petrological characteristics of the solids. However, there is in general no proportionality between BET specific surface areas and the capacity of the rocks for water adsorption at high temperatures. The results indicate that multilayer adsorption rather than capillary condensation is the dominant water storage mechanism at high temperatures.

  7. Studies on adsorption, reaction mechanisms and kinetics for photocatalytic degradation of CHD, a pharmaceutical waste.

    PubMed

    Sarkar, Santanu; Bhattacharjee, Chiranjib; Curcio, Stefano

    2015-11-01

    The photocatalytic degradation of chlorhexidine digluconate (CHD), a disinfectant and topical antiseptic and adsorption of CHD catalyst surface in dark condition has been studied. Moreover, the value of kinetic parameters has been measured and the effect of adsorption on photocatalysis has been investigated here. Substantial removal was observed during the photocatalysis process, whereas 40% removal was possible through the adsorption route on TiO2 surface. The parametric variation has shown that alkaline pH, ambient temperature, low initial substrate concentration, high TiO2 loading were favourable, though at a certain concentration of TiO2 loading, photocatalytic degradation efficiency was found to be maximum. The adsorption study has shown good confirmation with Langmuir isotherm and during the reaction at initial stage, it followed pseudo-first-order reaction, after that Langmuir Hinshelwood model was found to be appropriate in describing the system. The present study also confirmed that there is a significant effect of adsorption on photocatalytic degradation. The possible mechanism for adsorption and photocatalysis has been shown here and process controlling step has been identified. The influences of pH and temperature have been explained with the help of surface charge distribution of reacting particles and thermodynamic point of view respectively. PMID:25956186

  8. The adsorption properties of CO molecules on single-layer graphene nanoribbons

    SciTech Connect

    Yi, Chenglong; Wang, Weidong Shen, Cuili

    2014-03-15

    The adsorption properties of CO molecules on graphene nanoribbons (GRNs) are studied through the molecular dynamics (MD) method. The AIREBO and LJ potentials are used to describe the C-C bonds in GNR and the interactions between the carbon atoms in GNR and CO molecules, respectively. The influences of the environmental pressure and charge density on the adsorption properties of CO molecules on GRNs are taken into account in this study. The effects of charges carried by GNRs on the adsorption properties are investigated in two aspects: atom distribution and energy evolution. Its observation from the results shows that the Coulomb force plays a more important role in the adsorption phenomenon than the van der Waals force, and the higher the charge density is, the larger the amount of the adsorbed CO molecules becomes. Low charge densities (<3.291 C/m{sup 2}) do little for the system, that is to say, the GNRs present similar properties to the ones with no charges. However, relatively high charge densities (>4.937 C/m{sup 2}) have an obvious effect on the whole system. The results also indicate that the environmental pressure has great influence on the adsorption properties of COs on GRN, and the higher the pressure is, the greater the adsorption energy becomes.

  9. Dibenzothiophene adsorption at boron doped carbon nanoribbons studied within density functional theory

    SciTech Connect

    López-Albarrán, P.; Navarro-Santos, P.; Garcia-Ramirez, M. A.; Ricardo-Chávez, J. L.

    2015-06-21

    The adsorption of dibenzothiophene (DBT) on bare and boron-doped armchair carbon nanoribbons (ACNRs) is being investigated in the framework of the density functional theory by implementing periodic boundary conditions that include corrections from dispersion interactions. The reactivity of the ACNRs is characterized by using the Fukui functions as well as the electrostatic potential as local descriptors. Non-covalent adsorption mechanism is found when using the local Perdew-Becke-Ernzerhof functional, regardless of the DBT orientation and adsorption location. The dispersion interactions addition is a milestone to describe the adsorption process. The charge defects introduced in small number (i.e., by doping with B atoms), within the ACNRs increases the selectivity towards sulfur mainly due to the charge depletion at B sites. The DBT magnitude in the adsorption energy shows non-covalent interactions. As a consequence, the configurations where the DBT is adsorbed on a BC{sub 3} island increase the adsorption energy compared to random B arrangements. The stability of these configurations can be explained satisfactorily in terms of dipole interactions. Nevertheless, from the charge-density difference analysis and the weak Bader charge-distribution interactions cannot be ruled out completely. This is why the electronic properties of the ribbons are analyzed in order to elucidate the key role played by the B and DBT states in the adsorbed configurations.

  10. Polyelectrolyte adsorption onto like-charged surfaces mediated by trivalent counterions: A Monte Carlo simulation study

    NASA Astrophysics Data System (ADS)

    Luque-Caballero, Germán; Martín-Molina, Alberto; Quesada-Pérez, Manuel

    2014-05-01

    Both experiments and theory have evidenced that multivalent cations can mediate the interaction between negatively charged polyelectrolytes and like-charged objects, such as anionic lipoplexes (DNA-cation-anionic liposome complexes). In this paper, we use Monte Carlo simulations to study the electrostatic interaction responsible for the trivalent-counterion-mediated adsorption of polyelectrolytes onto a like-charged planar surface. The evaluation of the Helmholtz free energy allows us to characterize both the magnitude and the range of the interaction as a function of the polyelectrolyte charge, surface charge density, [3:1] electrolyte concentration, and cation size. Both polyelectrolyte and surface charge favor the adsorption. It should be stressed, however, that the adsorption will be negligible if the surface charge density does not exceed a threshold value. The effect of the [3:1] electrolyte concentration has also been analyzed. In certain range of concentrations, the counterion-mediated attraction seems to be independent of this parameter, whereas very high concentrations of salt weaken the adsorption. If the trivalent cation diameter is doubled the adsorption moderates due to the excluded volume effects. The analysis of the integrated charge density and ionic distributions suggests that a delicate balance between charge inversion and screening effects governs the polyelectrolyte adsorption onto like-charged surfaces mediated by trivalent cations.

  11. Removal of bisphenol A by adsorption mechanism using PES-SiO2 composite membranes.

    PubMed

    Muhamad, Mimi Suliza; Salim, Mohd Razman; Lau, Woei Jye; Hadibarata, Tony; Yusop, Zulkifli

    2016-08-01

    Polyethersulphone (PES) membranes blended with silicon dioxide (SiO2) nanoparticles were prepared via a dry-jet wet spinning technique for the removal of bisphenol A (BPA) by adsorption mechanism. The morphology of SiO2 nanoparticles was analysed using a transmission electron microscopy and particle size distribution was also analysed. The prepared membranes were characterized by several techniques including field emission scanning electron microscopy, Fourier transform infrared spectroscopy and water contact angle. The adsorption mechanism of membrane towards BPA was evaluated by batch experiments and kinetic model. The influence of natural organic matter (NOM) in feed water on membrane BPA removal was also studied by filtration experiments. Results showed that BPA adsorption capacity as high as 53 µg/g could be achieved by the PES membrane incorporated with 2 wt% SiO2 in which the adsorption mechanism was in accordance with the pseudo-second-order kinetic model. The intraparticles diffusion model suggested that the rate limiting factor of membrane adsorption mechanism is governed by the diffusion of BPA into the membrane pores. The presence of 10 ppm NOM has reported to negatively reduce BPA removal by 24%, as it tended to compete with BPA for membrane adsorption. This work has demonstrated that PES-SiO2 membrane has the potential to eliminate trace amount of BPA from water source containing NOM. PMID:26729509

  12. Effect of hydrophilicity of end-grafted polymers on protein adsorption behavior: A Monte Carlo study.

    PubMed

    Han, Yuanyuan; Jin, Jing; Cui, Jie; Jiang, Wei

    2016-06-01

    Monte Carlo simulation is employed to investigate protein adsorption behavior on end-grafted polymers. The effect of hydrophilicity of end-grafted polymers on protein adsorption behavior is investigated in detail. The simulation results indicate that the hydrophilicity of the end-grafted polymers can affect both the amount and speed of protein adsorption. An increase in the hydrophilicity of the end-grafted polymers can significantly decrease the amount and speed of protein adsorption first. However, a further increase in the hydrophilicity of the end-grafted polymers results in the increase in the amount and speed of protein adsorption. This phenomenon is easier to be observed in the end-grafted polymer systems with lower grafting density and longer chain length. In addition, the investigation of the chain conformation of the end-grafted polymers reveals that the end-grafted polymers with mediate hydrophilicity have relatively small size difference along the parallel and perpendicular directions to the substrate, and these end-grafted polymers have relatively wide height distribution. Such characteristics favor covering the space above the hydrophobic substrate and thus can effectively resist protein adsorption. PMID:26925724

  13. Modeling Neisseria meningitidis metabolism: from genome to metabolic fluxes

    PubMed Central

    Baart, Gino JE; Zomer, Bert; de Haan, Alex; van der Pol, Leo A; Beuvery, E Coen; Tramper, Johannes; Martens, Dirk E

    2007-01-01

    Background Neisseria meningitidis is a human pathogen that can infect diverse sites within the human host. The major diseases caused by N. meningitidis are responsible for death and disability, especially in young infants. In general, most of the recent work on N. meningitidis focuses on potential antigens and their functions, immunogenicity, and pathogenicity mechanisms. Very little work has been carried out on Neisseria primary metabolism over the past 25 years. Results Using the genomic database of N. meningitidis serogroup B together with biochemical and physiological information in the literature we constructed a genome-scale flux model for the primary metabolism of N. meningitidis. The validity of a simplified metabolic network derived from the genome-scale metabolic network was checked using flux-balance analysis in chemostat cultures. Several useful predictions were obtained from in silico experiments, including substrate preference. A minimal medium for growth of N. meningitidis was designed and tested succesfully in batch and chemostat cultures. Conclusion The verified metabolic model describes the primary metabolism of N. meningitidis in a chemostat in steady state. The genome-scale model is valuable because it offers a framework to study N. meningitidis metabolism as a whole, or certain aspects of it, and it can also be used for the purpose of vaccine process development (for example, the design of growth media). The flux distribution of the main metabolic pathways (that is, the pentose phosphate pathway and the Entner-Douderoff pathway) indicates that the major part of pyruvate (69%) is synthesized through the ED-cleavage, a finding that is in good agreement with literature. PMID:17617894

  14. Arsenic Metabolism and Distribution in Developing Organisms

    EPA Science Inventory

    A growing body of evidence suggests that exposure to inorganic arsenic during early life has long term adverse effects. The extent of exposure to inorganic arsenic and its methylated metabolites in utero is determined not only by the rates of formation and transfer of arsenicals...

  15. Cesium adsorption on composite ferrocyanide-aluminosilicate adsorbents

    SciTech Connect

    Panasyugin, A.S.; Rat`ko, A.I.; Trofimenko, N.E.

    1995-11-01

    The formation of composite ferrocyanide adsorbents prepared on the basis of clinoptilolite is studied by potentiometric titration, X-ray diffraction analysis, and IR spectroscopy, and the nature of ion-exchanging complex is established. Exchange capacity, selectivity, and hydrolytic stability of the sorbents are characterized. Distribution coefficients with modified samples can be as large as 10000 for {sup 137}Cs; however, with increase of the background salt concentration above 0.17 g l{sup -1}, competing ions have noticeable effect on the adsorption properties of the aluminosilicates.

  16. Adsorption and dissociation of molecular hydrogen on the (0001) surface of double hexagonal close packed americium

    NASA Astrophysics Data System (ADS)

    Dholabhai, P. P.; Ray, A. K.

    2009-01-01

    Hydrogen molecule adsorption on the (0001) surface of double hexagonal packed americium has been studied in detail within the framework of density functional theory using a full-potential all-electron linearized augmented plane wave plus local orbitals method (FP-L/APW+lo). Weak molecular hydrogen adsorptions were observed. Adsorption energies were optimized with respect to the distance of the adsorbates from the surface for three approach positions at three adsorption sites, namely t1 (one-fold top), b2 (two-fold bridge), and h3 (three-fold hollow) sites. Adsorption energies were computed at the scalar-relativistic level (no spin-orbit coupling NSOC) and at the fully relativistic level (with spin-orbit coupling SOC). The most stable configuration corresponds to a horizontal adsorption with the molecular approach being perpendicular to a lattice vector. The surface coverage is equivalent to one-fourth of a monolayer (ML), with the adsorption energies at the NSOC and SOC theoretical levels being 0.0997 eV and 0.1022 eV, respectively. The respective distance of the hydrogen molecule from the surface and hydrogen-hydrogen distance was found to be 2.645 Å and 0.789 Å, respectively. The work functions decreased and the net magnetic moments remained almost unchanged in all cases compared with the corresponding quantities of bare dhcp Am (0001) surface. The adsorbate-substrate interactions have been analyzed in detail using the partial charges inside the muffin-tin spheres, difference charge density distributions, and the local density of states. The effects of adsorption on the Am 5f electron localization-delocalization characteristics have been discussed. Reaction barrier for the dissociation of hydrogen molecule has been presented.

  17. Assessment of CO₂ adsorption capacity on activated carbons by a combination of batch and dynamic tests.

    PubMed

    Balsamo, Marco; Silvestre-Albero, Ana; Silvestre-Albero, Joaquín; Erto, Alessandro; Rodríguez-Reinoso, Francisco; Lancia, Amedeo

    2014-05-27

    In this work, batch and dynamic adsorption tests are coupled for an accurate evaluation of CO2 adsorption performance of three different activated carbons (AC) obtained from olive stones by chemical activation followed by physical activation with CO2 at varying times (i.e., 20, 40, and 60 h). Kinetic and thermodynamic CO2 adsorption tests from simulated flue gas at different temperatures and CO2 pressures are carried out under both batch (a manometric equipment operating with pure CO2) and dynamic (a lab-scale fixed-bed column operating with a CO2/N2 mixture) conditions. The textural characterization of the AC samples shows a direct dependence of both micropore and ultramicropore volume on the activation time; hence, AC60 has the higher contribution. The adsorption tests conducted at 273 and 293 K showed that when CO2 pressure is lower than 0.3 bar, the lower the activation time, the higher CO2 adsorption capacity; a ranking of ω(eq)(AC20) > ω(eq)(AC40) > ω(eq)(AC60) can be exactly defined when T = 293 K. This result is likely ascribed to the narrower pore size distribution of the AC20 sample, whose smaller pores are more effective for CO2 capture at higher temperature and lower CO2 pressure, the latter representing operating conditions of major interest for decarbonation of flue gas effluent. Moreover, the experimental results obtained from dynamic tests confirm the results derived from the batch tests in terms of CO2 adsorption capacity. It is important to highlight the fact that the adsorption of N2 on the synthesized AC samples can be considered to be negligible. Finally, the importance of proper analysis for data characterization and adsorption experimental results is highlighted for the correct assessment of the CO2 removal performance of activated carbons at different CO2 pressures and operating temperatures. PMID:24784997

  18. Optimization of mesoporous carbons for efficient adsorption of berberine hydrochloride from aqueous solutions.

    PubMed

    Li, Yin; Fu, Jie; Deng, Shuguang; Lu, Xiuyang

    2014-06-15

    Sixteen mesoporous carbon adsorbents were synthesized by varying the ratio of soft to hard templates in order to optimize the pore textural properties of these adsorbents. The mesoporous carbon adsorbents have a high BET specific surface area (1590.3-2193.5 m(2)/g), large pore volume (1.72-2.56 cm(3)/g), and uniform pore size distribution with a median pore diameter ranging from 3.51 nm to 4.52 nm. It was observed that pore textural properties of the carbon adsorbents critically depend on the molar ratio of carbon sources to templates, and the hard template plays a more important role than the soft template in manipulating the pore textures. Adsorption isotherms of berberine hydrochloride at 303 K were measured to evaluate the adsorption efficacy of these adsorbents. The adsorption of berberine hydrochloride from aqueous solutions on the sixteen mesoporous carbon adsorbents synthesized in this work is very efficient, and the adsorption equilibrium capacities on all samples are more than double the adsorption capacities of berberine hydrochloride of the benchmark adsorbents (polymer resins and spherical activated carbons) at similar conditions. It was observed from the adsorption experiments that the equilibrium adsorption amounts of berberine hydrochloride are strongly correlated with the BET specific surface area and pore volume of the adsorbents. The adsorbent with the highest BET of 2193.5 m(2)/g displayed the largest adsorption capacity of 574 mg/g at an equilibrium concentration of 0.10mg/mL of berberine hydrochloride in an aqueous solution. PMID:24767505

  19. Adsorption site analysis of impurity embedded single-walled carbon nanotube bundles

    USGS Publications Warehouse

    Agnihotri, S.; Mota, J.P.B.; Rostam-Abadi, M.; Rood, M.J.

    2006-01-01

    Bundle morphology and adsorptive contributions from nanotubes and impurities are studied both experimentally and by simulation using a computer-aided methodology, which employs a small physisorbed probe molecule to explore the porosity of nanotube samples. Grand canonical Monte Carlo simulation of nitrogen adsorption on localized sites of a bundle is carried out to predict adsorption in its accessible internal pore volume and on its external surface as a function of tube diameter. External adsorption is split into the contributions from the clean surface of the outermost nanotubes of the bundle and from the surface of the impurities. The site-specific isotherms are then combined into a global isotherm for a given sample using knowledge of its tube-diameter distribution obtained by Raman spectroscopy. The structural parameters of the sample, such as the fraction of open-ended nanotubes and the contributions from impurities and nanotube bundles to total external surface area, are determined by fitting the experimental nitrogen adsorption data to the simulated isotherm. The degree of closure between experimental and calculated adsorption isotherms for samples manufactured by two different methods, to provide different nanotube morphology and contamination level, further strengthens the validity and resulting interpretations based on the proposed approach. The average number of nanotubes per bundle and average bundle size, within a sample, are also quantified. The proposed method allows for extrapolation of adsorption properties to conditions where the purification process is 100% effective at removing all impurities and opening access to all intrabundle adsorption sites. ?? 2006 Elsevier Ltd. All rights reserved.

  20. The effect of dose on 2,3,7,8-TCDD tissue distribution, metabolism and elimination in CYP1A2(-/_) knockout and C57BL/6N parental strains of mice

    EPA Science Inventory

    Numerous metabolism studies have demonstrated that the toxic contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is poorly metabolized. A hallmark feature of TCDD exposure is induction of hepatic CYP1A2 and subsequent sequestration leading to high liver-to-fat concentration ra...

  1. The Effect of Dose on 2,3,7,8-TCDD Tissue Distribution, Metabolism and Elimination in CYP1A2 (-/-) Knockout and C57BL/6N Parental Strains of Mice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Numerous metabolism studies have demonstrated that the highly toxic 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is poorly metabolized. A hallmark feature of TCDD exposure is induction of hepatic CYP1A2 and subsequent sequestration leading to high liver to fat concentration ratios. This study was in...

  2. Adsorption of Rh(III) complexes from chloride solutions obtained by leaching chlorinated spent automotive catalysts on ion-exchange resin Diaion WA21J.

    PubMed

    Shen, Shaobo; Pan, Tonglin; Liu, Xinqiang; Yuan, Lei; Wang, Jinchao; Zhang, Yongjian; Guo, Zhanchen

    2010-07-15

    It was found that Rh, Pd and Pt contained in the spent ceramic automotive catalysts could be effectively extracted by dry chlorination with chlorine. In order to concentrate Rh(III) ions contained in the chloride solutions obtained, thermodynamic and kinetics studies for adsorption of Rh(III) complexes from the chloride solutions on an anionic exchange resin Diaion WA21J were carried out. Rh, Pd, Pt, Al, Fe, Si, Zn and Pb from the chloride solution could be adsorbed on the resin. The distribution coefficients (K(d)) of Rh(III) decreased with the increase in initial Rh(III) concentration or in adsorption temperature. The isothermal adsorption of Rh(III) was found to fit Langmuir, Freundlich and Dubinin-Kaganer-Radushkevich models under the adsorption conditions. The maximum monolayer adsorption capacities Q(max) based on Langmuir adsorption isotherms were 6.39, 6.61 and 5.81 mg/g for temperatures 18, 28 and 40 degrees C, respectively. The apparent adsorption energy of Rh was about -7.6 kJ/mol and thus Rh(III) adsorption was a physical type. The experimental data obtained could be better simulated by pseudo-first-order kinetic model and the activation energy obtained was 6.54 J/mol. The adsorption rate of Rh(III) was controlled by intraparticle diffusion in most of time of adsorption process. PMID:20346581

  3. Adsorption affinity of anions on metal oxyhydroxides

    NASA Astrophysics Data System (ADS)

    Pechenyuk, S. I.; Semushina, Yu. P.; Kuz'mich, L. F.

    2013-03-01

    The dependences of anion (phosphate, carbonate, sulfate, chromate, oxalate, tartrate, and citrate) adsorption affinity anions from geometric characteristics, acid-base properties, and complex forming ability are generalized. It is shown that adsorption depends on the nature of both the anions and the ionic medium and adsorbent. It is established that anions are generally grouped into the following series of adsorption affinity reduction: PO{4/3-}, CO{3/2-} > C2O{4/2-}, C(OH)(CH2)2(COO){3/3-}, (CHOH)2(COO){2/2-} > CrO{4/2-} ≫ SO{4/2-}.

  4. Carbon monoxide adsorption on beryllium surfaces

    NASA Astrophysics Data System (ADS)

    Allouche, A.

    2013-02-01

    Density functional calculations are here carried out to study the carbon monoxide molecule adsorption on pristine, hydrogenated and hydroxylated beryllium Be (0001) surfaces. The adsorption energies and structures, the activation barriers to molecular adsorption and dissociation are calculated. These reactions are described in terms of potential energy surfaces and electronic density of states. The quantum results are discussed along two directions: the beryllium surface reactivity in the domain of nuclear fusion devices and the possible usage of beryllium as a catalyst of Fischer-Tropsch-type synthesis.

  5. Adsorption of lead over Graphite Oxide

    PubMed Central

    Olanipekun, Opeyemi; Oyefusi, Adebola; Neelgund, Gururaj M.; Oki, Aderemi

    2014-01-01

    The adsorption efficiency and kinetics of removal of lead in presence of graphite oxide (GO) was determined using the Atomic Absorption spectrophotometer (AAS). The GO was prepared by the chemical oxidation of graphite and characterized using FTIR, SEM, TGA and XRD. The adsorption efficiency of GO for the solution containing 50, 100 and 150 ppm of Pb2+ was found to be 98, 91 and 71% respectively. The adsorption ability of GO was found to be higher than graphite. Therefore, the oxidation of activated carbon in removal of heavy metals may be a viable option to reduce pollution in portable water. PMID:24152870

  6. Random sequential adsorption of trimers and hexamers.

    PubMed

    Cieśla, Michał; Barbasz, Jakub

    2013-12-01

    Adsorption of trimers and hexamers built of identical spheres was studied numerically using the random sequential adsorption (RSA) algorithm. Particles were adsorbed on a two-dimensional, flat and homogeneous surface. Numerical simulations allowed us to determine the maximal random coverage ratio, RSA kinetics as well as the available surface function (ASF), which is crucial for determining the kinetics of the adsorption process obtained experimentally. Additionally, the density autocorrelation function was measured. All the results were compared with previous results obtained for spheres, dimers and tetramers. PMID:24193213

  7. Amino Acid Metabolism Disorders

    MedlinePlus

    ... defects & other health conditions > Amino acid metabolism disorders Amino acid metabolism disorders E-mail to a friend Please ... baby’s newborn screening may include testing for certain amino acid metabolism disorders. These are rare health conditions that ...

  8. Comprehensive metabolic panel

    MedlinePlus

    A comprehensive metabolic panel is a group of blood tests. They provide an overall picture of your body's chemical balance and metabolism. Metabolism refers to all the physical and chemical processes ...

  9. Carbohydrate Metabolism Disorders

    MedlinePlus

    Metabolism is the process your body uses to make energy from the food you eat. Food is ... disorder, something goes wrong with this process. Carbohydrate metabolism disorders are a group of metabolic disorders. Normally ...

  10. Blueberries and Metabolic Syndrome

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Metabolic Syndrome is a cluster of metabolic disorders that increase the risk of cardiovascular diseases. Type 2 diabetes, elevated blood pressure, and atherogenic dyslipidemia are among the metabolic alterations that predispose the individual to several adverse cardiovascular complications. The hea...

  11. Adsorption of selected pharmaceuticals and an endocrine disrupting compound by granular activated carbon. 1. Adsorption capacity and kinetics

    SciTech Connect

    Yu, Z.; Peldszus, S.; Huck, P.M.

    2009-03-01

    The adsorption of two representative PhACs (naproxen and carbamazepine) and one EDC (nonylphenol) were evaluated on two granular activated carbons (GAC) namely coal-based Calgon Filtrasorb 400 and coconut shell-based PICA CTIF TE. The primary objective was to investigate preloading effects by natural organic matter (NOM) on adsorption capacity and kinetics under conditions and concentrations (i.e., ng/L) relevant for drinking water treatment. Isotherms demonstrated that all compounds were significantly negatively impacted by NOM fouling. Adsorption capacity reduction was most severe for the acidic naproxen, followed by the neutral carbamazepine and then the more hydrophobic nonylphenol. The GAC with the wider pore size distribution had considerably greater NOM loading, resulting in lower adsorption capacity. Different patterns for the change in Freundlich KF and 1/n with time revealed different competitive mechanisms for the different compounds. Mass transport coefficients determined by short fixed-bed (SFB) tests with virgin and preloaded GAC demonstrated that film diffusion primarily controls mass transfer on virgin and preloaded carbon. Naproxen suffered the greatest deteriorative effect on kinetic parameters due to preloading, followed by carbamazepine, and then nonylphenol. A type of surface NOM/biofilm, which appeared to add an additional mass transfer resistance layer and thus reduce film diffusion, was observed. In addition, electrostatic interactions between NOM/biofilm and the investigated compounds are proposed to contribute to the reduction of film diffusion. A companion paper building on this work describes treatability studies in pilot-scale GAC adsorbers and the effectiveness of a selected fixed-bed model. 32 refs., 3 figs., 2 tabs.

  12. DNA adsorption onto glass surfaces

    NASA Astrophysics Data System (ADS)

    Carlson, Krista Lynn

    Streaming potential measurements were performed on microspheres of silica, lime silicate (SLS) and calcium aluminate (CA) glasses containing silica and iron oxide (CASi and CAFe). The silicate based glasses exhibited acidic surfaces with isoelectric points (IEP) around a pH of 3 while the calcium aluminates displayed more basic surfaces with IEP ranging from 8--9.5. The surface of the calcium aluminate microspheres containing silica reacted with the background electrolyte, altering the measured zeta potential values and inhibiting electrolyte flow past the sample at ˜ pH 4 due to formation of a solid plug. DNA adsorption experiments were performed using the microspheres and a commercially available silicate based DNA isolation filter using a known quantity of DNA suspended in a chaotropic agent free 0.35 wt% Tris(hydroxymethyl)aminomethane (Tris) buffer solution. The microspheres and commercial filter were also used to isolate DNA from macrophage cells in the presence of chaotropic agents. UV absorbance at ˜260 nm and gel electrophoresis were used to quantify the amount and size of the DNA strands that adsorbed to the microsphere surfaces. In both experiments, the 43--106 microm CAFe microspheres adsorbed the largest quantity of DNA. However, the 43--106 microm SLS microspheres isolated more DNA from the cells than the <43 microm CAFe microspheres, indicating that microsphere size contributes to isolation ability. The UV absorbance of DNA at ˜260 nm was slightly altered due to the dissolution of the calcium aluminate glasses during the adsorption process. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) determined that calcium and aluminum ions leached from the CA and CAFe microsphere surfaces during these experiments. Circular dichroism (CD) spectroscopy showed that the leached ions had no effect on the conformation of the DNA, and therefore would not be expected to interfere in downstream applications such as DNA replication. The 0.35 wt

  13. Correlating N2 and CH4 adsorption on microporous carbon using a new analytical model

    USGS Publications Warehouse

    Sun, Jielun; Chen, S.; Rood, M.J.; Rostam-Abadi, M.

    1998-01-01

    A new pore size distribution (PSD) model is developed to readily describe PSDs of microporous materials with an analytical expression. Results from this model can be used to calculate the corresponding adsorption isotherm to compare the calculated isotherm to the experimental isotherm. This aspect of the model provides another check on the validity of the model's results. The model is developed on the basis of a 3-D adsorption isotherm equation that is derived from statistical mechanical principles. Least-squares error minimization is used to solve the PSD without any preassumed distribution function. In comparison with several well-accepted analytical methods from the literature, this 3-D model offers a relatively realistic PSD description for select reference materials, including activated-carbon fibers. N2 and CH4 adsorption is correlated using the 3-D model for commercial carbons BPL and AX-21. Predicted CH4 adsorption isotherms at 296 K based on N2 adsorption at 77 K are in reasonable agreement with experimental CH4 isotherms. Use of the model is also described for characterizing PSDs of tire-derived activated carbons and coal-derived activated carbons for air-quality control applications.

  14. Albumin (BSA) Adsorption over Graphene in Aqueous Environment: Influence of Orientation, Adsorption Protocol, and Solvent Treatment.

    PubMed

    Vilhena, J G; Rubio-Pereda, Pamela; Vellosillo, Perceval; Serena, P A; Pérez, Rubén

    2016-02-23

    We report 150 ns explicit solvent MD simulations of the adsorption on graphene of albumin (BSA) in two orientations and using two different adsorption protocols, i.e., free and forced adsorption. Our results show that free adsorption occurs with little structural rearrangements. Even taking adsorption to an extreme, by forcing it with a 5 nN downward force applied during the initial 20 ns, we show that along a particular orientation BSA is able to preserve the structural properties of the majority of its binding sites. Furthermore, in all the cases considered in this work, the ibuprofen binding site has shown a strong resilience to structural changes. Finally, we compare these results with implicit solvent simulations and find that the latter predicts an extreme protein unfolding upon adsorption. The origin of this discrepancy is attributed to a poor description of the water entropic forces at interfaces in the implicit solvent methods. PMID:26799950

  15. ADSORPTION OF ORGANIC CATIONS TO SOILS AND SUBSURFACE MATERIALS

    EPA Science Inventory

    A study of the fundamentals of adsorption of amphiphilic organic cations on natural and pristine surfaces was conducted to elucidate (i) the factors that influence the extent of adsorption and (ii) indirect effects of adsorption of organic cations: the competitive adsorption of o...

  16. EVALUATING MULTICOMPONENT COMPETITIVE ADSORPTION IN FIXED BEDS

    EPA Science Inventory

    An equilibrium column model (ECM) was developed to evaluate multicomponent competition in fixed-bed adsorption columns. The model ignores mass transfer resistances and uses ideal adsorbed solution theory to predict the competitive effects in multicomponent mixtures. The bed capac...

  17. Fluorocarbon Adsorption in Hierarchical Porous Frameworks

    SciTech Connect

    Motkuri, Radha K.; Annapureddy, Harsha V.; Vijayakumar, M.; Schaef, Herbert T.; Martin, P F.; McGrail, B. Peter; Dang, Liem X.; Krishna, Rajamani; Thallapally, Praveen K.

    2014-07-09

    The adsorption behavior of a series of fluorocarbon derivatives was examined on a set of microporous metal organic framework (MOF) sorbents and another set of hierarchical mesoporous MOFs. The microporous M-DOBDC (M = Ni, Co) showed a saturation uptake capacity for R12 of over 4 mmol/g at a very low relative saturation pressure (P/Po) of 0.02. In contrast, the mesoporous MOF MIL-101 showed an exceptionally high uptake capacity reaching over 14 mmol/g at P/Po of 0.4. Adsorption affinity in terms of mass loading and isosteric heats of adsorption were found to generally correlate with the polarizability of the refrigerant with R12 > R22 > R13 > R14 > methane. These results suggest the possibility of exploiting MOFs for separation of azeotropic mixtures of fluorocarbons and use in eco-friendly fluorocarbon-based adsorption cooling and refrigeration applications.

  18. Krypton based adsorption type cryogenic refrigerator

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor); Schember, Helene R. (Inventor)

    1989-01-01

    Krypton and a monolithic porous carbon such as Saran carbon are used respectively as the sorbate and sorbent of an adsorption type refrigerator to improve refrigeration efficiency and operational longevity.

  19. Adsorption Isotherms and Surface Reaction Kinetics

    ERIC Educational Resources Information Center

    Lobo, L. S.; Bernardo, C. A.

    1974-01-01

    Explains an error that occurs in calculating the conditions for a maximum value of a rate expression for a bimolecular reaction. The rate expression is derived using the Langmuir adsorption isotherm to relate gas pressures and corresponding surface coverages. (GS)

  20. Argon adsorption and the lunar atmosphere

    NASA Technical Reports Server (NTRS)

    Bernatowicz, T. J.; Podosek, F. A.

    1991-01-01

    The results of Ar adsorption experiments on a terrestrial labradorite and lunar rock 15415 crushed in vacuo are reported. The experiments were designed to test lunar atmosphere simulation models for the behavior of Ar on the lunar surface, as determined from the Apollo 17 mass spectrometer results. These models (Hodges, 1980, 1982) used a single adsorption potential to characterize the surfaces of lunar soil grains, with the result that high (6-7 kcal/mol) heats of adsorption were inferred. The present experimental results show that very high adsorption potentials are indeed associated with fresh mineral surfaces, but that these energetic surfaces occupy only small fractions of the total surface area. Nonetheless, these small fractions of surface, if they can be maintained in the lunar regolith in steady-state condition, could be sufficient to account for the Apollo 17 mass spectrometer observations.

  1. Adsorption of nisin and pediocin on nanoclays.

    PubMed

    Meira, Stela Maris Meister; Jardim, Arthur Izé; Brandelli, Adriano

    2015-12-01

    Three different nanoclays (bentonite, octadecylamine-modified montmorillonite and halloysite) were studied as potential carriers for the antimicrobial peptides nisin and pediocin. Adsorption occurred from peptide solutions in contact with nanoclays at room temperature. Higher adsorption of nisin and pediocin was obtained on bentonite. The antimicrobial activity of the resultant bacteriocin-nanoclay systems was analyzed using skimmed milk agar as food simulant and the largest inhibition zones were observed against Gram-positive bacteria for halloysite samples. Bacteriocins were intercalated into the interlayer space of montmorillonites as deduced from the increase of the basal spacing measured by X-ray diffraction (XRD) assay. Infrared spectroscopy suggested non-electrostatic interactions, such as hydrogen bonding between siloxane groups from clays and peptide molecules. Transmission electron microscopy did not show any alteration in morphologies after adsorption of antimicrobial peptides on bentonite and halloysite. These results indicate that nanoclays, especially halloysite, are suitable nanocarriers for nisin and pediocin adsorption. PMID:26041178

  2. Adsorption of sulfur dioxide by native clinoptilolite

    SciTech Connect

    Merkun, I.I.; Kel'tsev, N.V.; Bratchuk, F.N.; Rogovik, M.I.

    1982-11-10

    The purpose of the present work was to study the adsorption capacity of the little-studied native clinoptilolite from Beregovo in the Zakarpatskaya region (Ruthenia) for sulfur dioxide. Adsorption of SO/sub 2/ under analogous conditions by Patrick's silica gel, prepared by us by a known method, was studied for comparison. Results indicated that native clinoptilolite studied has much higher adsorption capacity than Patrick's silica gel for sulfur dioxide in the temperature range studied. The adsorption capacity of this zeolite alters little with increase of temperature in the range 25-75/sup 0/. It is considered that native clinoptilolite can be used for removing sulfur dioxide from waste gases in the temperature and pressure ranges studied.

  3. Nanoporous chalcogenides for adsorption and gas separation.

    PubMed

    Ori, Guido; Massobrio, Carlo; Pradel, Annie; Ribes, Michel; Coasne, Benoit

    2016-05-21

    The adsorption and gas separation properties of amorphous porous chalcogenides such as GeS2 are investigated using statistical mechanics molecular simulation. Using a realistic molecular model of such amorphous adsorbents, we show that they can be used efficiently to separate different gases relevant to environmental and energy applications (H2, CO2, CH4, N2). In addition to shedding light on the microscopic adsorption mechanisms, we show that coadsorption in this novel class of porous materials can be described using the ideal adsorbed solution theory (IAST). Such a simple thermodynamic model, which allows avoiding complex coadsorption measurements, describes the adsorption of mixture from pure component adsorption isotherms. Our results, which are found to be in good agreement with available experimental data, paves the way for the design of gas separation membranes using the large family of porous chalcogenides. PMID:27126718

  4. Methane Adsorption on Aggregates of Fullerenes: Site-Selective Storage Capacities and Adsorption Energies

    PubMed Central

    Kaiser, Alexander; Zöttl, Samuel; Bartl, Peter; Leidlmair, Christian; Mauracher, Andreas; Probst, Michael; Denifl, Stephan; Echt, Olof; Scheier, Paul

    2013-01-01

    Methane adsorption on positively charged aggregates of C60 is investigated by both mass spectrometry and computer simulations. Calculated adsorption energies of 118–281 meV are in the optimal range for high-density storage of natural gas. Groove sites, dimple sites, and the first complete adsorption shells are identified experimentally and confirmed by molecular dynamics simulations, using a newly developed force field for methane–methane and fullerene–methane interaction. The effects of corrugation and curvature are discussed and compared with data for adsorption on graphite, graphene, and carbon nanotubes. PMID:23744834

  5. Characterizing Nitrogen adsorption and desorption isotherms in soils using multifractal analysis

    NASA Astrophysics Data System (ADS)

    Paz Ferreiro, Jorge; Miranda, José G. V.; Vidal Vázquez, Eva

    2010-05-01

    desorption isotherms were on average 0.761 with a range from 0.682 to 0.722. The entropy dimension D1 is a measure of diversity in a multifractal system and it is also an index of the dispersion of the measure. The values of D1 for adsorption isotherms were much lower than those for desorption isotherms. This indicates that for adsorption isotherms most of the measure concentrates in a small size domain of the study scale, whereas for desorption isotherms it was somewhat more evenly distributed. On the other hand, the Hölder exponent of order zero, α0, was significantly greater for adsorption isotherms (1.396) when compared with desorption curves (1.246). Therefore, adsorption isotherms exhibit on average a lower degree of mass concentration (i.e. the lowest local density) than desorption isotherms. Moreover, the width of the singularity spectra was larger for adsorption than for desorption isotherms, which means a higher heterogeneity in the local scaling indices of the former variable. The potential usefulness in soil science of the multifractal characteristics extracted from the adsorption and desorption isotherms is discussed. Paz-Ferreiro, J., Wilson, M., and Vidal Vázquez, E. (2009). Multifractal description on Nitrogen adsorption isotherms. Vadose Zone Journal 8: 209-219. Acknowledgement: This work was supported by Spanish Ministry of Education (Project CGL2006-13068-C02) and Xunta de Galicia (Project INCITE08PXIB162169PR).

  6. Adsorption of chlorophenols on granular activated carbon

    SciTech Connect

    Yang, M.

    1993-12-31

    Studies were undertaken of the adsorption of chlorinated phenols from aqueous solution on granular activated carbon (Filtrasorb-400, 30 x 40 mesh). Single-component equilibrium adsorption data on the eight compounds in two concentration ranges at pH 7.0 fit the Langmuir equation better than the Freundlich equation. The adsorptive capacities at pH 7.0 increase from pentachlorophenol to trichlorophenols and are fairly constant from trichlorophenols to monochlorophenols. The adsorption process was found to be exothermic for pentachlorophenol and 2,4,6-trichlorophenol, and endothermic for 2,4-dichlorophenol and 4-chlorophenol. Equilibrium measurements were also conducted for 2,4,5-trichlorophenol, 2,4-dichlorophenol, and 4-chlorophenol over a wide pH range. A surface complexation model was proposed to describe the effect of pH on adsorption equilibria of chlorophenols on activated carbon. The simulations of the model are in excellent agreement with the experimental data. Batch kinetics studies were conducted of the adsorption of chlorinated phenols on granular activated carbon. The results show that the surface reaction model best describes both the short-term and long-term kinetics, while the external film diffusion model describes the short-term kinetics data very well and the linear-driving-force approximation improved its performance for the long-term kinetics. Multicomponent adsorption equilibria of chlorophenols on granular activated carbon was investigated in the micromolar equilibrium concentration range. The Langmuir competitive and Ideal Adsorbed Solution (IAS) models were tested for their performance on the three binary systems of pentachlorophenol/2,4,6-trichlorophenol, 2,4,6-trichlorophenol/2,4-dichlorophenol, and 2,4-dichlorophenol/4-chlorophenol, and the tertiary system of 2,4,6-trichlorophenol/2,4-dichlorophenol/4-chlorophenol, and found to fail to predict the two-component adsorption equilibria of the former two binary systems and the tertiary system.

  7. A fundamental study of the impact of pressure on the adsorption mechanism in reversed-phase liquid chromatography.

    PubMed

    Åsberg, Dennis; Samuelsson, Jörgen; Fornstedt, Torgny

    2016-07-29

    A fundamental investigation of the pressure effect on individual adsorption sites was undertaken based on adsorption energy distribution and adsorption isotherm measurements. For this purpose, we measured adsorption equilibrium data at pressures ranging from 100 to 1000bar at constant flow and over a wide concentration range for three low-molecular-weight solutes, antipyrine, sodium 2-naphthalenesulfonate, and benzyltriethylammonium chloride, on an Eternity C18 stationary phase. The adsorption energy distribution was bimodal for all solutes, remaining clearly so at all pressures. The bi-Langmuir model best described the adsorption in these systems and two types of adsorption sites were identified, one with a low and another with a high energy of interaction. Evidence exists that the low-energy interactions occur at the interface between the mobile and stationary phases and that the high-energy interactions occur nearer the silica surface, deeper in the C18 layer. The contribution of each type of adsorption site to the retention factor was calculated and the change in solute molar volume from the mobile to stationary phase during the adsorption process was estimated for each type of site. The change in solute molar volume was 2-4 times larger at the high-energy site, likely because of the greater loss of solute solvation layer when penetrating deeper into the C18 layer. The association equilibrium constant increased with increasing pressure while the saturation capacity of the low-energy site remained almost unchanged. The observed increase in saturation capacity for the high-energy site did not affect the column loading capacity, which was almost identical at 50- and 950-bar pressure drops over the column. PMID:27357740

  8. Theory of polyelectrolyte adsorption on heterogeneously charged surfaces applied to soluble protein-polyelectrolyte complexes

    NASA Astrophysics Data System (ADS)

    de Vries, R.; Weinbreck, F.; de Kruif, C. G.

    2003-03-01

    Existing theoretical approaches to polymer adsorption on heterogeneous surfaces are applied to the problems of polyelectrolyte and polyampholyte adsorption on randomly charged surfaces. Also, analytical estimates are developed for the critical pH at which weakly charged polyelectrolytes and globular proteins start forming soluble complexes. Below a critical salt concentration, soluble complexes form "on the wrong side" of the protein isoelectric point due to the heterogeneity of the protein surface charge distribution. The analytical estimates are consistent with experimental data on soluble complexes in mixtures of gum arabic and whey protein isolate.

  9. Adsorption of aqueous copper on peanut hulls

    NASA Astrophysics Data System (ADS)

    Davis, Kanika Octavia

    A method was established for measuring the adsorption of Cu(II) from aqueous solution to unmodified and modified peanut hulls at constant temperature and pH. Modification of the hulls was performed by oxidation with alkaline hydrogen peroxide. During the modification process, the hydrogen peroxide solubilizes the lignin component, making the surface more porous which increases the availability of binding sites, while simultaneously oxidizing the cellulose. The oxidation of alcohol groups creates more binding sites by creating functional groups such as COO-, which increases chelation to metal ions. Fourier transform infrared spectroscopy confirms delignification of the peanut hulls by the disappearance of carboxyl peaks of the modified hulls, which were originally produced from the lignin content. Although, oxidation is not fully confirmed, it is not ruled out because the expected carboxylate peak (1680 cm-1) maybe overshadowed by a broad peak due to OH bending of water adsorbed to the hulls. Hulls adsorbed copper from solutions in the concentration range of 50-1000 ppm of CuCl2. Concentrations of pre- and post-adsorption solutions were determined using inductively coupled plasma optical emission spectroscopy. The adsorption isotherms were fit to known two and three-parameter models, evaluated and the binding mechanism was inferred. Maximum surface coverage was 3.5 +/- 0.6 mg Cu2+ /g hull for unmodified hulls and 11 +/- 1 mg Cu2+/g hull for modified hulls. The adsorption for the hulls is best described by the Langmuir model, suggesting monolayer, homogeneous adsorption. With a free energy of adsorption of 10.5 +/- 0.9 kJ/mol for unmodified hulls and 14.5 +/-0.4 kJ/mol for modified hulls, the process is categorized as chemisorption for both types of hulls. The adsorption for both hulls is also described by the Redlich-Peterson model, giving beta nearer to 1 than 0, which further suggests homogeneous adsorption described by the Langmuir model. After rinsing the hulls

  10. Assessing the Adsorption Properties of Shales

    NASA Astrophysics Data System (ADS)

    Pini, R.

    2014-12-01

    Fine-grained rocks, such as shales, contain a significant amount of nanopores that can significantly contribute to their storage capacity through the mechanism of adsorption. The current ability to extract natural gas that is adsorbed in the rock's matrix is limited and current technology focuses primarily on the free gas in the fractures, thus leading to very low recovery efficiencies. Shales constitute also a great portion of so-called caprocks above potential CO2 sequestration sites; hereby, the adsorption process may limit the CO2 mobility within the cap-rock, thus minimizing leakage phenomena. Whether it is a reservoir or a caprock, understanding and quantifying the mechanisms of adsorption in these natural materials is key to improve the engineering design of subsurface operations. Results will be presented from a laboratory study that combines conventional techniques for the measurement of adsorption isotherms with novel methods that allows for the imaging of adsorption using x-rays. Various nanoporous materials are considered, thus including rocks, such as shales and coals, pure clay minerals and engineered adsorbents with well-defined nanopore structures, such as zeolites. Supercritical CO2 adsorption isotherms have been measured with a Rubotherm Magnetic Suspension balance by covering the pressure range 0.1-20~MPa. A medical x-ray CT scanner has been used to identify three-dimensional patterns of the adsorption properties of a packed-bed of adsorbent, thus enabling to assess the spatial variability of the adsorption isotherm. The data are analyzed by using thermodynamically rigorous measures of adsorption and a graphical method is applied for their interpretation. The density of the adsorbed phase is estimated and compared to data reported in the literature; the latter is key to disclose gas-reserves and/or potential storage capacity estimates. When evaluated against classic adsorbent materials, the adsorption mechanism in shales is further complicated by

  11. Disorders of Amino Acid Metabolism

    MedlinePlus

    ... Aspiration Syndrome Additional Content Medical News Disorders of Amino Acid Metabolism By Lee M. Sanders, MD, MPH NOTE: ... Metabolic Disorders Disorders of Carbohydrate Metabolism Disorders of Amino Acid Metabolism Disorders of Lipid Metabolism Amino acids are ...

  12. Pharmacokinetics and metabolism of the plant cannabinoids, delta9-tetrahydrocannabinol, cannabidiol and cannabinol.

    PubMed

    Huestis, M A

    2005-01-01

    Increasing interest in the biology, chemistry, pharmacology, and toxicology of cannabinoids and in the development of cannabinoid medications necessitates an understanding of cannabinoid pharmacokinetics and disposition into biological fluids and tissues. A drug's pharmacokinetics determines the onset, magnitude, and duration of its pharmacodynamic effects. This review of cannabinoid pharmacokinetics encompasses absorption following diverse routes of administration and from different drug formulations, distribution of analytes throughout the body, metabolism by different tissues and organs, elimination from the body in the feces, urine, sweat, oral fluid, and hair, and how these processes change over time. Cannabinoid pharmacokinetic research has been especially challenging due to low analyte concentrations, rapid and extensive metabolism, and physicochemical characteristics that hinder the separation of drugs of interest from biological matrices--and from each other--and lower drug recovery due to adsorption of compounds of interest to multiple surfaces. delta9-Tetrahydrocannabinol, the primary psychoactive component of Cannabis sativa, and its metabolites 11-hydroxy-delta9-tetrahydrocannabinol and 11-nor-9-carboxy-tetrahydrocannabinol are the focus of this chapter, although cannabidiol and cannabinol, two other cannabinoids with an interesting array of activities, will also be reviewed. Additional material will be presented on the interpretation of cannabinoid concentrations in human biological tissues and fluids following controlled drug administration. PMID:16596792

  13. Adsorption of atrazine on soils: model study.

    PubMed

    Kovaios, Ilias D; Paraskeva, Christakis A; Koutsoukos, Petros G; Payatakes, Alkiviades Ch

    2006-07-01

    The adsorption of the widely used herbicide atrazine onto three model inorganic soil components (silica gel, gamma-alumina, and calcite (CaCO(3)) was investigated in a series of batch experiments in which the aqueous phase equilibrated with the solid, under different solution conditions. Atrazine did not show discernible adsorption on gamma-alumina (theta=25 degrees C, 3.8adsorption from solutions was found for silica gel suspensions. The adsorption isotherms obtained for atrazine uptake on silica gel particles were best fitted with the Freundlich model. An increase of the ionic strength of the electrolytic solution induced an increase of the surface concentration of atrazine on silica gel, indicating significant electrostatic interactions between atrazine and silica gel particles, possibly through interaction with the surface silanol groups of the solid substrate. Increase of the pH value of the electrolyte solution from 6 to 9 considerably decreased the amount of atrazine adsorbed on the silica gel substrate. Decrease of the solution pH from 6 to 3 had only a slight effect on the surface concentration of the adsorbed atrazine. The adsorption of atrazine on silica gel increased when the temperature was decreased from 40 to 25 degrees C, an indication that the adsorption is exothermic. The calculated enthalpy of adsorption ( approximately 10 kJ/mol) indicates that the uptake at the solid-liquid equilibrium pH (6.1) was largely due to physisorption. PMID:16556447

  14. Microcystin-LR Adsorption by Activated Carbon.

    PubMed

    Pendleton, Phillip; Schumann, Russell; Wong, Shiaw Hui

    2001-08-01

    We use a selection of wood-based and coconut-based activated carbons to investigate the factors controlling the removal of the hepatotoxin microcystin-LR (m-LR) from aqueous solutions. The wood carbons contain both micropores and mesopores. The coconut carbons contain micropores only. Confirming previously published observations, we also find that the wood-based carbons adsorb more microcystin than the coconut-based carbons. From a combination of a judicious modification of a wood-based carbon's surface chemistry and of the solution chemistry, we demonstrate that both surface and solution chemistry play minor roles in the adsorption process, with the adsorbent surface chemistry exhibiting less influence than the solution chemistry. Conformational changes at low solution pH probably contribute to the observed increase in adsorption by both classes of adsorbent. At the solution pH of 2.5, the coconut-based carbons exhibit a 400% increased affinity for m-LR compared with 100% increases for the wood-based carbons. In an analysis of the thermodynamics of adsorption, using multiple temperature adsorption chromatography methods, we indicate that m-LR adsorption is an entropy-driven process for each of the carbons, except the most hydrophilic and mesoporous carbon, B1. In this case, exothermic enthalpy contributions to adsorption also exist. From our overall observations, since m-LR contains molecular dimensions in the secondary micropore width range, we demonstrate that it is important to consider both the secondary micropore and the mesopore volumes for the adsorption of m-LR from aqueous solutions. Copyright 2001 Academic Press. PMID:11446779

  15. Poliovirus Adsorption by 34 Minerals and Soils

    PubMed Central

    Moore, Rebecca S.; Taylor, Dene H.; Sturman, Lawrence S.; Reddy, Michael M.; Fuhs, G. Wolfgang

    1981-01-01

    The adsorption of radiolabeled infectious poliovirus type 2 by 34 well-defined soils and mineral substrates was analyzed in a synthetic freshwater medium containing 1 mM CaCl2 and 1.25 mM NaHCO3 at pH 7. In a model system, adsorption of poliovirus by Ottawa sand was rapid and reached equilibrium within 1 h at 4°C. Near saturation, the adsorption could be described by the Langmuir equation; the apparent surface saturation was 2.5 × 106 plaque-forming units of poliovirus per mg of Ottawa sand. At low surface coverage, adsorption was described by the Freundlich equation. The soils and minerals used ranged from acidic to basic and from high in organic content to organic free. The available negative surface charge on each substrate was measured by the adsorption of a cationic polyelectrolyte, polydiallyldimethylammonium chloride. Most of the substrates adsorbed more than 95% of the virus. In general, soils, in comparison with minerals, were weak adsorbents. Among the soils, muck and Genesee silt loam were the poorest adsorbents; among the minerals, montmorillonite, glauconite, and bituminous shale were the least effective. The most effective adsorbents were magnetite sand and hematite, which are predominantly oxides of iron. Correlation coefficients for substrate properties and virus adsorption revealed that the elemental composition of the adsorbents had little effect on poliovirus uptake. Substrate surface area and pH, by themselves, were not significantly correlated with poliovirus uptake. A strong negative correlation was found between poliovirus adsorption and both the contents of organic matter and the available negative surface charge on the substrates as determined by their capacities for adsorbing the cationic polyelectrolyte, polydiallyldimethylammonium chloride. PMID:6274259

  16. Adsorption behavior and mechanism of chloramphenicols, sulfonamides, and non-antibiotic pharmaceuticals on multi-walled carbon nanotubes.

    PubMed

    Zhao, Heng; Liu, Xue; Cao, Zhen; Zhan, Yi; Shi, Xiaodong; Yang, Yi; Zhou, Junliang; Xu, Jiang

    2016-06-01

    The adsorption behavior of different emerging contaminants (3 chloramphenicols, 7 sulfonamides, and 3 non-antibiotic pharmaceuticals) on five types of multi-walled carbon nanotubes (MWCNTs), and the underlying factors were studied. Adsorption equilibriums were reached within 12h for all compounds, and well fitted by the Freundlich isotherm model. The adsorption affinity of pharmaceuticals was positively related to the specific surface area of MWCNTs. The solution pH was an important parameter of pharmaceutical adsorption on MWCNTs, due to its impacts on the chemical speciation of pharmaceuticals and the surface electrical property of MWCNTs. The adsorption of ionizable pharmaceuticals decreased in varying degrees with the increased ionic strength. MWCNT-10 was found to be the strongest adsorbent in this study, and the Freundlich constant (KF) values were 353-2814mmol(1-n)L(n)/kg, 571-618mmol(1-n)L(n)/kg, and 317-1522mmol(1-n)L(n)/kg for sulfonamides, chloramphenicols, and non-antibiotic pharmaceuticals, respectively. The different adsorption affinity of sulfonamides might contribute to the different hydrophobic of heterocyclic substituents, while chloramphenicols adsorption was affected by the charge distribution in aromatic rings via substituent effects. PMID:26937870

  17. The adsorption mechanism of nortryptiline on C18-bonded discovery

    SciTech Connect

    Gritti, Fabrice; Guiochon, Georges A

    2005-08-01

    The adsorption isotherms of an ionizable compound, nortriptyline, were accurately measured by frontal analysis (FA) on a C{sub 18}-Discovery column, first without buffer (in an aqueous solution of acetonitrile at 15%, v/v of ACN), then with a buffer (in 28%, v/v ACN solution). The buffers were aqueous solutions containing 20 mM of formic acid or a phosphate buffer at pH 2.70. The linear range of the isotherm could not be reached with the non-buffered mobile phase using a dynamic range larger than 40,000 (from 1.2 x 10{sup -3} g/L to 50 g/L). With a 20 mM buffer in the liquid phase, the isotherm is linear for concentrations of nortriptyline inferior to 10{sup -3} g/L (or 3 {micro} mol/L). The adsorption energy distribution (AED) was calculated to determine the heterogeneity of the adsorption process. AED and FA were consistent and lead to a trimodal distribution. A tri-Moreau and a tri-Langmuir isotherm models accounted the best for the adsorption of nortriptyline without and with buffer, respectively. The nature of the buffer affects significantly the middle-energy sites while the properties of the lowest and highest of the three types of energy sites are almost unchanged. The desorption profiles of nortriptyline show some anomalies in relation with the formation of a complex multilayer adsorbed phase of acetonitrile whose excess isotherm was measured by the minor disturbance method. The C{sub 18}-Discovery column has about the same total saturation capacity, around 200 g of nortriptyline per liter of adsorbent (or 116 mg/g), with or without buffer. About 98-99% of the available surface consists in low energy sites. The coexistence of these different types of sites on the surface solves the McCalley's enigma, that the column efficiency begins to drop rapidly when the analyte concentration reaches values that are almost one hundred times lower than those that could be predicted from the isotherm data acquired under the same experimental conditions. Due to the

  18. Methane adsorption and dissociation on iron oxide oxygen carriers: the role of oxygen vacancies.

    PubMed

    Cheng, Zhuo; Qin, Lang; Guo, Mengqing; Fan, Jonathan A; Xu, Dikai; Fan, Liang-Shih

    2016-06-28

    We performed ab initio DFT+U calculations to explore the interaction between methane and iron oxide oxygen carriers for chemical looping reaction systems. The adsorption of CH4 and CHx (x = 0-3) radicals on α-Fe2O3(001), and the influence of oxygen vacancies at the top surface and on the subsurface on the adsorption properties of the radicals was investigated. The adsorption strength for CH4 and C radicals at the top of the α-Fe2O3(001) surface in the presence of oxygen vacancies is lower than that on the stoichiometric surface. However, for methyl (CH3), methylene (CH2) and methine (CH) radicals, it is correspondingly higher. In contrast, the oxygen vacancy formation on the subsurface not only increases the adsorption strength of CH3, CH2 and CH radicals, but also facilitates C radical adsorption. We found that oxygen vacancies significantly affect the adsorption configuration of CHx radicals, and determine the probability of finding an adsorbed species in the stoichiometric region and the defective region at the surface. With the obtained adsorption geometries and energetics of these species adsorbed on the surface, we extend the analysis to CH4 dissociation under chemical looping reforming conditions. The distribution of adsorbed CH4 and CHx (x = 0-3) radicals is calculated and analyzed which reveals the relationship between adsorbed CHx radical configuration and oxygen vacancies in iron oxide. Also, the oxygen vacancies can significantly facilitate CH4 activation by lowering the dissociation barriers of CH3, CH2 and CH radicals. However, when the oxygen vacancy concentration reaches 2.67%, increasing the oxygen vacancy concentration cannot continue to lower the CH dissociation barrier. The study provides fundamental insights into the mechanism of CH4 dissociation on iron based oxygen carriers and also provide guidance to design more efficient oxygen carriers. PMID:27265327

  19. [Bone metabolic markers and diagnosis of abnormal bone and calcium metabolism].

    PubMed

    Fukunaga, M; Sone, T

    2001-07-01

    Bone metabolic markers increase in blood or urine, when bone formation or bone resorption accelerates. Reference values of bone metabolic markers are determined in male or female, and in pre- or post-menopause, respectively. Values of bone metabolic markers in most patients with primary osteoporosis were distributed within a reference value, mean+/-1.96 SD. When measured values exceeded a reference values, we should survey a possibility of abnormal calcium or bone metabolism such as primary hyperparathyroidism, renal osteodystrophy, hyperthyroidism and Paget's disease of bone or bone metastasis associated with malignant tumor. PMID:15775589

  20. Revisiting the adsorption of copper-phthalocyanine on Au(111) including van der Waals corrections

    SciTech Connect

    Lüder, Johann; Eriksson, Olle; Sanyal, Biplab; Brena, Barbara

    2014-03-28

    We have studied the adsorption of copper-phthalocyanine on Au(111) by means of van der Waals corrected density functional theory using the Tkatchenko-Scheffler method. We have compared the element and site resolved adsorption distances to recent experimental normal-incident X-ray standing wave measurements. The measured adsorption distances could be reproduced within a deviation of 1% for the Cu atom, 1% for the C atoms, and 2% for the N atoms. The molecule was found to have a magnetic moment of 1 μ{sub B} distributed over the Cu and the N atoms of the pyrrole ring. Simulated scanning tunnel microscopy images based on the total and on the spin-resolved differential charge densities are provided for bias voltages of −1.45 and 1.45 eV.

  1. Revisiting the adsorption of copper-phthalocyanine on Au(111) including van der Waals corrections.

    PubMed

    Lüder, Johann; Eriksson, Olle; Sanyal, Biplab; Brena, Barbara

    2014-03-28

    We have studied the adsorption of copper-phthalocyanine on Au(111) by means of van der Waals corrected density functional theory using the Tkatchenko-Scheffler method. We have compared the element and site resolved adsorption distances to recent experimental normal-incident X-ray standing wave measurements. The measured adsorption distances could be reproduced within a deviation of 1% for the Cu atom, 1% for the C atoms, and 2% for the N atoms. The molecule was found to have a magnetic moment of 1 μB distributed over the Cu and the N atoms of the pyrrole ring. Simulated scanning tunnel microscopy images based on the total and on the spin-resolved differential charge densities are provided for bias voltages of -1.45 and 1.45 eV. PMID:24697474

  2. Molecular properties affecting the adsorption coefficient of pesticides from various chemical families.

    PubMed

    Langeron, Julie; Blondel, Alodie; Sayen, Stéphanie; Hénon, Eric; Couderchet, Michel; Guillon, Emmanuel

    2014-01-01

    Forty pesticides were selected in function of their chemical families and their physico-chemical properties to represent a wide range of pesticide properties. Adsorption of these pesticides was studied on two soils by batch experiments. The two soils differed largely in organic matter and calcite contents. Distribution coefficient Kd was determined for each pesticide on the two soils. Adsorption was higher for the soil having the highest organic matter content and the lowest calcite content. In order to identify pesticide properties governing retention, eight molecular descriptors were determined from three-dimensional (3D) structure of molecules. Class-specific quantitative structure properties relationship (QSPR) soil adsorption models using one and two parameters were developed from experimental Kd. Three properties seemed to influence most retention of pesticides: hydrophobicity, solubility, and polarisability. Models combining these properties were suggested and discussed. PMID:24801285

  3. From single molecules to water networks: Dynamics of water adsorption on Pt(111).

    PubMed

    Naderian, Maryam; Groß, Axel

    2016-09-01

    The adsorption dynamics of water on Pt(111) was studied using ab initio molecular dynamics simulations based on density functional theory calculations including dispersion corrections. Sticking probabilities were derived as a function of initial kinetic energy and water coverage. In addition, the energy distribution upon adsorption was monitored in order to analyze the energy dissipation process. We find that on the water pre-covered surface the sticking probability is enhanced because of the attractive water-water interaction and the additional effective energy dissipation channels to the adsorbed water molecules. The water structures forming directly after the adsorption on the pre-covered surfaces do not necessarily correspond to energy minimum structures. PMID:27609006

  4. Enhancement of As(V) adsorption onto activated sludge by methylation treatment.

    PubMed

    Kang, So-Young; Kim, Dong-Wook; Kim, Kyoung-Woong

    2007-08-01

    Biosorption properties of arsenate [As(V)] onto activated sludge were investigated in batch systems. The adsorption of As(V) onto sludge increased from 23 to 266 microg/g dry weight through the methylation of the activated sludge. This increase resulted from neutralization of carboxylic groups via the methylation process. The pH effect of As(V) uptake was also investigated and As(V) adsorption by methylated sludge decreased significantly at high pH (pH > 11) due to competition between As(V) and OH(-) ions for binding sites distributed on sludge surfaces. In contrast, low pH favored As(V) adsorption by methylated sludge because of the elevated quantities of positively charged functional groups. The results suggest that methylated activated sludge may provide promising applications for the simultaneous removal and separation of As(V) from aqueous effluents. PMID:17505894

  5. Method and apparatus for thermal swing adsorption and thermally-enhanced pressure swing adsorption

    DOEpatents

    Wegeng, Robert S.; Rassat, Scot D.; TeGrotenhuis, Ward E.; Drost, Kevin; Vishwanathan, Vilayanur V.

    2004-06-08

    The present invention provides compact adsorption systems that are capable of rapid temperature swings and rapid cycling. Novel methods of thermal swing adsorption and thermally-enhanced pressure swing adsorption are also described. In some aspects of the invention, a gas is passed through the adsorbent thus allowing heat exchangers to be very close to all portions of the adsorbent and utilize less space. In another aspect, the adsorption media is selectively heated, thus reducing energy costs. Methods and systems for gas adsorption/desorption having improved energy efficiency with capability of short cycle times are also described. In another aspect, the apparatus or methods utilize heat exchange channels of varying lengths that have volumes controlled to provide equal heat fluxes. Methods of fuel cell startup are also described. Advantages of the invention include the ability to use (typically) 30-100 times less adsorbent compared to conventional systems.

  6. Method for thermal swing adsorption and thermally-enhanced pressure swing adsorption

    DOEpatents

    Wegeng, Robert S.; Rassat, Scot D.; Stenkamp, Victoria S.; TeGrotenhuis, Ward E.; Matson, Dean W.; Drost, M. Kevin; Viswanathan, Vilayanur V.

    2003-10-07

    The present invention provides compact adsorption systems that are capable of rapid temperature swings and rapid cycling. Novel methods of thermal swing adsorption and thermally-enhanced pressure swing adsorption are also described. In some aspects of the invention, a gas is passed through the adsorbent thus allowing heat exchangers to be very close to all portions of the adsorbent and utilize less space. In another aspect, the adsorption media is selectively heated, thus reducing energy costs. Methods and systems for gas adsorption/desorption having improved energy efficiency with capability of short cycle times are also described. Advantages of the invention include the ability to use (typically) 30-100 times less adsorbent compared to conventional systems.

  7. Apparatus for thermal swing adsorption and thermally-enhanced pressure swing adsorption

    DOEpatents

    Wegeng, Robert S.; Rassat, Scot D.; Stenkamp, Victoria S.; TeGrotenhuis, Ward E.; Matson, Dean W.; Drost, M. Kevin; Viswanathan, Vilayanur V.

    2005-12-13

    The present invention provides compact adsorption systems that are capable of rapid temperature swings and rapid cycling. Novel methods of thermal swing adsorption and thermally-enhanced pressure swing adsorption are also described. In some aspects of the invention, a gas is passed through the adsorbent thus allowing heat exchangers to be very close to all portions of the adsorbent and utilize less space. In another aspect, the adsorption media is selectively heated, thus reducing energy costs. Methods and systems for gas adsorption/desorption having improved energy efficiency with capability of short cycle times are also described. Advantages of the invention include the ability to use (typically) 30-100 times less adsorbent compared to conventional systems.

  8. The effect of dose on 2,3,7,8-TCDD tissue distribution, metabolism and elimination in CYP1A2 (-/-) knockout and C57BL/6N parental strains of mice

    SciTech Connect

    Hakk, Heldur; Diliberto, Janet J.; Birnbaum, Linda S.

    2009-11-15

    Numerous metabolism studies have demonstrated that the toxic contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is poorly metabolized. A hallmark feature of TCDD exposure is induction of hepatic CYP1A2 and subsequent sequestration leading to high liver-to-fat concentration ratios. This study was initiated to determine whether TCDD was inherently poorly metabolized or unavailable for metabolism because of sequestration to CYP1A2. [{sup 3}H]TCDD was administered as a single, oral dose (0.1 and 10 mug/kg) to 12 male C57BL/6N mice or 12 CYP1A2 (-/-) mice. At 96 h, less than 5% of the dose was eliminated in the urine of all groups, and TCDD detected in urine was bound to mouse major urinary protein (mMUP). Feces were the major elimination pathway (24-31% of dose), and fecal extracts and non-extractables were quantitated by HPLC for metabolites. No great differences in urinary or fecal elimination (% dose) were observed between the high and low dose treatments. TCDD concentrations were the highest in adipose tissue for CYP1A2 knockout mice but in liver for C57BL/6N mice supporting the role of hepatic CYP1A2 in the sequestration of TCDD. Overall metabolism between parental and knockout strains showed no statistical differences at either the high or low doses. The data suggested that metabolism of TCDD is inherently slow, due principally to CYP1A1, and that hepatic CYP1A2 is not an active participant in the metabolism of TCDD in male mice. Rather, CYP1A2 governs the pharmacokinetics of TCDD by making it unavailable for hepatic CYP1A1 through sequestration and attenuating extrahepatic tissue disposition.

  9. Neptunium(V) adsorption to calcite.

    PubMed

    Heberling, Frank; Brendebach, Boris; Bosbach, Dirk

    2008-12-12

    The migration behavior of the actinyl ions U(VI)O2(2+), Np(V)O2+ and Pu(V,VI)O2(+,2+) in the geosphere is to a large extend controlled by sorption reactions (inner- or outer-sphere adsorption, ion-exchange, coprecipitation/structural incorporation) with minerals. Here NpO2+ adsorption onto calcite is studied in batch type experiments over a wide range of pH (6.0-9.4) and concentration (0.4 microM-40 microM) conditions. pH is adjusted by variation of CO2 partial pressure. Adsorption is found to be pH dependent with maximal adsorption at pH 8.3 decreasing with increasing and decreasing pH. pH dependence of adsorption decreases with increasing Np(V) concentration. EXAFS data of neptunyl adsorbed to calcite and neptunyl in the supernatant shows differences in the Np(V)-O-yl distance, 1.85+/-0.01 angstroms for the adsorbed and 1.82+/-0.01 angstroms for the solution species. The equatorial environment of the neptunyl in solution shows about 5 oxygen neighbours at 2.45+/-0.02 angstroms. For adsorbed neptunyl there are also about 5 oxygen neighbours at 2.46+/-0.01 angstroms. An additional feature in the adsorbed species' R-space spectrum can be related to carbonate neighbours, 3 to 6 carbon backscatterers (C-eq) at 3.05+/-0.03 angstroms and 3 to 6 oxygen backscatterers (O-eq2) at 3.31+/-0.02 angstroms. The differences in the Np(V)-O-yl distance and the C-eq and O-eq2 backscatterers which are only present for the adsorbed species indicate inner-sphere bonding of the adsorbed neptunyl species to the calcite surface. Experiments on adsorption kinetics indicate that after a fast surface adsorption process a continuous slow uptake occurs which may be explained by incorporation via surface dissolution and reprecipitation processes. This is also indicated by the part irreversibility of the adsorption as shown by increased KD values after desorption compared to adsorption. PMID:18973965

  10. Adsorption of aniline and toluidines on montmorillonite

    SciTech Connect

    Essington, M.E. )

    1994-09-01

    Bentonite clay liners are commonly employed to mitigate the movement of contaminants from waste disposal sites. In order to assess the ability of clay liner material to restrict the mobility of amine compounds under a variety of chemical conditions and to further elucidate amine adsorption characteristics, the adsorption of aniline and o-, m-, and p-toluidine on Ca[sup 2+]- and K[sup +]-saturated Wyoming bentonite (SWy-1) was investigated. Adsorption experiments were performed under conditions of varied pH and ionic environment. Amine adsorption on montmorillonite is pH dependent. Maximum amine adsorption occurs when solution pH is approximately equal to the pK[sub a] of the anilinium ion deprotonation reaction (pH 4.45-5.08). An amine adsorption envelope results from the combined influence of increasing anilinium ion and anilinium-aniline complex formation (as pH decreases to the pK[sub a]) and amine competition with H[sup +] for surface sites, decreasing anilinium-aniline complex concentration, and decreasing aniline available for water bridging with exchangeable Ca[sup 2+] and K[sup +] (as solution pH decreases below the pK[sub a]). For any given amine, maximum adsorption increases with decreasing ionic strength. Maximum amine adsorption is greater in the Ca[sup 2+] systems than in the K[sup +] systems at equivalent cation charge and reflects the formation of an amine water bridge with the exchangeable Ca[sup 2+]. Amine adsorption is also greater in chloride systems compared with sulfate systems at comparable cation concentrations, possibly due to the formation of aqueous anilinium-sulfate complexes. The amine compounds are retained mainly by bentonite through a cation exchange process, the capacity of the clay to adsorb the amine compounds being a significant percentage of the exchange capacity at the pK[sub a]. However, amine retention decreases with increasing pH and is minimal at solution pH values greater than 7. 19 refs., 6 figs.

  11. The Evolution of Fungal Metabolic Pathways

    PubMed Central

    Rokas, Antonis

    2014-01-01

    Fungi contain a remarkable range of metabolic pathways, sometimes encoded by gene clusters, enabling them to digest most organic matter and synthesize an array of potent small molecules. Although metabolism is fundamental to the fungal lifestyle, we still know little about how major evolutionary processes, such as gene duplication (GD) and horizontal gene transfer (HGT), have interacted with clustered and non-clustered fungal metabolic pathways to give rise to this metabolic versatility. We examined the synteny and evolutionary history of 247,202 fungal genes encoding enzymes that catalyze 875 distinct metabolic reactions from 130 pathways in 208 diverse genomes. We found that gene clustering varied greatly with respect to metabolic category and lineage; for example, clustered genes in Saccharomycotina yeasts were overrepresented in nucleotide metabolism, whereas clustered genes in Pezizomycotina were more common in lipid and amino acid metabolism. The effects of both GD and HGT were more pronounced in clustered genes than in their non-clustered counterparts and were differentially distributed across fungal lineages; specifically, GD, which was an order of magnitude more abundant than HGT, was most frequently observed in Agaricomycetes, whereas HGT was much more prevalent in Pezizomycotina. The effect of HGT in some Pezizomycotina was particularly strong; for example, we identified 111 HGT events associated with the 15 Aspergillus genomes, which sharply contrasts with the 60 HGT events detected for the 48 genomes from the entire Saccharomycotina subphylum. Finally, the impact of GD within a metabolic category was typically consistent across all fungal lineages, whereas the impact of HGT was variable. These results indicate that GD is the dominant process underlying fungal metabolic diversity, whereas HGT is episodic and acts in a category- or lineage-specific manner. Both processes have a greater impact on clustered genes, suggesting that metabolic gene clusters

  12. Periodic Mesoporous Organosilica Nanocubes with Ultrahigh Surface Areas for Efficient CO2 Adsorption

    NASA Astrophysics Data System (ADS)

    Wei, Yong; Li, Xiaomin; Zhang, Renyuan; Liu, Yong; Wang, Wenxing; Ling, Yun; El-Toni, Ahmed Mohamed; Zhao, Dongyuan

    2016-02-01

    Ultrahigh surface area single-crystals of periodic mesoporous organosilica (PMOs) with uniform cubic or truncated-cubic morphology and organic/inorganic components homogeneously distributed over the whole frameworks have successfully been prepared by a sol-gel surfactant-templating method. By tuning the porous feature and polymerization degree, the surface areas of the obtained PMO nanocubes can reach as high as 2370 m2/g, which is the highest for silica-based mesoporous materials. The ultrahigh surface area of the obtained PMO single crystals is mainly resulted from abundant micropores in the mesoporous frameworks. Furthermore, the diameter of the nanocubes can also be well controlled from 150 to 600 nm. The materials show ultrahigh CO2 adsorption capacity (up to 1.42 mmol/g at 273 K) which is much higher than other porous silica materials and comparable to some carbonaceous materials. The adsorption of CO2 into the PMO nanocubes is mainly in physical interaction, therefore the adsorption-desorption process is highly reversible and the adsorption capacity is much dependent on the surface area of the materials. Moreover, the selectivity is also very high (~11 times to N2) towards CO2 adsorption.

  13. Periodic Mesoporous Organosilica Nanocubes with Ultrahigh Surface Areas for Efficient CO2 Adsorption

    PubMed Central

    Wei, Yong; Li, Xiaomin; Zhang, Renyuan; Liu, Yong; Wang, Wenxing; Ling, Yun; El-Toni, Ahmed Mohamed; Zhao, Dongyuan

    2016-01-01

    Ultrahigh surface area single-crystals of periodic mesoporous organosilica (PMOs) with uniform cubic or truncated-cubic morphology and organic/inorganic components homogeneously distributed over the whole frameworks have successfully been prepared by a sol-gel surfactant-templating method. By tuning the porous feature and polymerization degree, the surface areas of the obtained PMO nanocubes can reach as high as 2370 m2/g, which is the highest for silica-based mesoporous materials. The ultrahigh surface area of the obtained PMO single crystals is mainly resulted from abundant micropores in the mesoporous frameworks. Furthermore, the diameter of the nanocubes can also be well controlled from 150 to 600 nm. The materials show ultrahigh CO2 adsorption capacity (up to 1.42 mmol/g at 273 K) which is much higher than other porous silica materials and comparable to some carbonaceous materials. The adsorption of CO2 into the PMO nanocubes is mainly in physical interaction, therefore the adsorption-desorption process is highly reversible and the adsorption capacity is much dependent on the surface area of the materials. Moreover, the selectivity is also very high (~11 times to N2) towards CO2 adsorption. PMID:26868049

  14. Water adsorption isotherms on porous onionlike carbonaceous particles. Simulations with the grand canonical Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Hantal, György; Picaud, Sylvain; Hoang, Paul N. M.; Voloshin, Vladimir P.; Medvedev, Nikolai N.; Jedlovszky, Pál

    2010-10-01

    The grand canonical Monte Carlo method is used to simulate the adsorption isotherms of water molecules on different types of model soot particles. These soot models are constructed by first removing atoms from onion-fullerene structures in order to create randomly distributed pores inside the soot, and then performing molecular dynamics simulations, based on the reactive adaptive intermolecular reactive empirical bond order (AIREBO) description of the interaction between carbon atoms, to optimize the resulting structures. The obtained results clearly show that the main driving force of water adsorption on soot is the possibility of the formation of new water-water hydrogen bonds with the already adsorbed water molecules. The shape of the calculated water adsorption isotherms at 298 K strongly depends on the possible confinement of the water molecules in pores of the carbonaceous structure. We found that there are two important factors influencing the adsorption ability of soot. The first of these factors, dominating at low pressures, is the ability of the soot of accommodating the first adsorbed water molecules at strongly hydrophilic sites. The second factor concerns the size and shape of the pores, which should be such that the hydrogen bonding network of the water molecules filling them should be optimal. This second factor determines the adsorption properties at higher pressures.

  15. Water adsorption isotherms on porous onionlike carbonaceous particles. Simulations with the grand canonical Monte Carlo method.

    PubMed

    Hantal, György; Picaud, Sylvain; Hoang, Paul N M; Voloshin, Vladimir P; Medvedev, Nikolai N; Jedlovszky, Pál

    2010-10-14

    The grand canonical Monte Carlo method is used to simulate the adsorption isotherms of water molecules on different types of model soot particles. These soot models are constructed by first removing atoms from onion-fullerene structures in order to create randomly distributed pores inside the soot, and then performing molecular dynamics simulations, based on the reactive adaptive intermolecular reactive empirical bond order (AIREBO) description of the interaction between carbon atoms, to optimize the resulting structures. The obtained results clearly show that the main driving force of water adsorption on soot is the possibility of the formation of new water-water hydrogen bonds with the already adsorbed water molecules. The shape of the calculated water adsorption isotherms at 298 K strongly depends on the possible confinement of the water molecules in pores of the carbonaceous structure. We found that there are two important factors influencing the adsorption ability of soot. The first of these factors, dominating at low pressures, is the ability of the soot of accommodating the first adsorbed water molecules at strongly hydrophilic sites. The second factor concerns the size and shape of the pores, which should be such that the hydrogen bonding network of the water molecules filling them should be optimal. This second factor determines the adsorption properties at higher pressures. PMID:20950025

  16. Periodic Mesoporous Organosilica Nanocubes with Ultrahigh Surface Areas for Efficient CO₂ Adsorption.

    PubMed

    Wei, Yong; Li, Xiaomin; Zhang, Renyuan; Liu, Yong; Wang, Wenxing; Ling, Yun; El-Toni, Ahmed Mohamed; Zhao, Dongyuan

    2016-01-01

    Ultrahigh surface area single-crystals of periodic mesoporous organosilica (PMOs) with uniform cubic or truncated-cubic morphology and organic/inorganic components homogeneously distributed over the whole frameworks have successfully been prepared by a sol-gel surfactant-templating method. By tuning the porous feature and polymerization degree, the surface areas of the obtained PMO nanocubes can reach as high as 2370 m(2)/g, which is the highest for silica-based mesoporous materials. The ultrahigh surface area of the obtained PMO single crystals is mainly resulted from abundant micropores in the mesoporous frameworks. Furthermore, the diameter of the nanocubes can also be well controlled from 150 to 600 nm. The materials show ultrahigh CO2 adsorption capacity (up to 1.42 mmol/g at 273 K) which is much higher than other porous silica materials and comparable to some carbonaceous materials. The adsorption of CO2 into the PMO nanocubes is mainly in physical interaction, therefore the adsorption-desorption process is highly reversible and the adsorption capacity is much dependent on the surface area of the materials. Moreover, the selectivity is also very high (~11 times to N2) towards CO2 adsorption. PMID:26868049

  17. Viruses at Solid-Water Interfaces: A Systematic Assessment of Interactions Driving Adsorption.

    PubMed

    Armanious, Antonius; Aeppli, Meret; Jacak, Ronald; Refardt, Dominik; Sigstam, Thérèse; Kohn, Tamar; Sander, Michael

    2016-01-19

    Adsorption to solid-water interfaces is a major process governing the fate of waterborne viruses in natural and engineered systems. The relative contributions of different interaction forces to adsorption and their dependence on the physicochemical properties of the viruses remain, however, only poorly understood. Herein, we systematically studied the adsorption of four bacteriophages (MS2, fr, GA, and Qβ) to five model surfaces with varying surface chemistries and to three dissolved organic matter adlayers, as a function of solution pH and ionic strength, using quartz crystal microbalance with dissipation monitoring. The viruses were selected to have similar sizes and shapes but different surface charges, polarities, and topographies, as identified by modeling the distributions of amino acids in the virus capsids. Virus-sorbent interactions were governed by long-ranged electrostatics and favorable contributions from the hydrophobic effect, and shorter-ranged van der Waals interactions were of secondary importance. Steric effects depended on the topographic irregularities on both the virus and sorbent surfaces. Differences in the adsorption characteristics of the tested viruses were successfully linked to differences in their capsid surface properties. Besides identifying the major interaction forces, this work highlights the potential of computable virus surface charge and polarity descriptors to predict virus adsorption to solid-water interfaces. PMID:26636722

  18. Kinetics and thermodynamics of adsorption of methylene blue by a magnetic graphene-carbon nanotube composite

    NASA Astrophysics Data System (ADS)

    Wang, Peifang; Cao, Muhan; Wang, Chao; Ao, Yanhui; Hou, Jun; Qian, Jin

    2014-01-01

    A solvothermal method was employed to prepare a novel magnetic composite adsorbent composed of graphene, multi-walled carbon nanotubes (MWCNTs) and Fe3O4 nanoparticles. The prepared adsorbents were characterized by X-ray diffraction, scanning electron microscopy and X-ray fluorescence spectrometry and Fourier transform infrared spectroscopy. Fourier transform infrared spectroscopy and the particle size distribution of the samples before and after adsorption was also carried out. The performance of as-prepared composites was investigated by the adsorption of dye methylene blue. Results showed that the maximum adsorption capacity of the samples was up to 65.79 mg g-1, which was almost equal to the sum of magnetic graphene and magnetic MWCNTs. The effect of pH and temperature on the adsorption performance of methylene blue onto the magnetic adsorbents was investigated. The kinetic was well-described by pseudo-second-order and intraparticle diffusion model, while the isotherm obeyed the Langmuir isotherm. Furthermore, the as-prepared composites were found to be regenerative and reusable. The application in the treatment of an artificial dye wastewater and its cost estimation were also discussed. Therefore, the as-prepared magnetic composites can be severed as a potential adsorbent for removal of dye pollutant, owing to its high adsorption performance, magnetic separability and efficient recyclable property.

  19. Membrane potential generated by ion adsorption.

    PubMed

    Tamagawa, Hirohisa; Morita, Sachi

    2014-01-01

    It has been widely acknowledged that the Goldman-Hodgkin-Katz (GHK) equation fully explains membrane potential behavior. The fundamental facet of the GHK equation lies in its consideration of permeability of membrane to ions, when the membrane serves as a separator for separating two electrolytic solutions. The GHK equation describes that: variation of membrane permeability to ion in accordance with ion species results in the variation of the membrane potential. However, nonzero potential was observed even across the impermeable membrane (or separator) separating two electrolytic solutions. It gave rise to a question concerning the validity of the GHK equation for explaining the membrane potential generation. In this work, an alternative theory was proposed. It is the adsorption theory. The adsorption theory attributes the membrane potential generation to the ion adsorption onto the membrane (or separator) surface not to the ion passage through the membrane (or separator). The computationally obtained potential behavior based on the adsorption theory was in good agreement with the experimentally observed potential whether the membrane (or separator) was permeable to ions or not. It was strongly speculated that the membrane potential origin could lie primarily in the ion adsorption on the membrane (or separator) rather than the membrane permeability to ions. It might be necessary to reconsider the origin of membrane potential which has been so far believed explicable by the GHK equation. PMID:24957176

  20. Adsorption behavior of heavy metals on biomaterials.

    PubMed

    Minamisawa, Mayumi; Minamisawa, Hiroaki; Yoshida, Shoichiro; Takai, Nobuharu

    2004-09-01

    We have investigated adsorption of Cd(II) and Pb(II) at pH 2-6.7 onto the biomaterials chitosan, coffee, green tea, tea, yuzu, aloe, and Japanese coarse tea, and onto the inorganic adsorbents, activated carbon and zeolite. High adsorptive capabilities were observed for all of the biomaterials at pH 4 and 6.7. In the adsorption of Cd(II), blend coffee, tea, green tea, and coarse tea have comparable loading capacities to activated carbon and zeolite. Although activated carbon, zeolite, and chitosan are utilized in a variety of fields such as wastewater treatment, chemical and metallurgical engineering, and analytical chemistry, these adsorbents are costly. On the other hand, processing of the test biomaterials was inexpensive, and all the biomaterials except for chitosan were able to adsorb large amounts of Pb(II) and Cd(II) ions after a convenient pretreatment of washing with water followed by drying. The high adsorption capability of the biomaterials prepared from plant materials is promising in the development of a novel, low-cost adsorbent. From these results, it is concluded that heavy metal removal using biomaterials would be an effective method for the economic treatment of wastewater. The proposed adsorption method was applied to the determination of amounts of Cd(II) and Pb(II) in water samples. PMID:15373400

  1. CF4 Adsorption on Open Carbon Nanohorns

    NASA Astrophysics Data System (ADS)

    Khanal, Pravin; Russell, Brice; Migone, Aldo; Iijima, Sumio; Yudasaka, Masako

    We have measured adsorption isotherms at ten different temperatures between 90.4 K and 163.8 K for CF4 on a sample of chemically-opened carbon nanohorns. The interior of the individual nanohorns is accessible to sorbates in these chemically-opened nanohorns. Two substeps are visible in the adsorption data, one corresponding to groups of stronger binding sites (lower pressure substep) and another corresponding to weaker binding sites (higher pressure substep). The stronger binding sites are interstitial pore-like spaces within the nanohorn aggregates and intra-nanohorns pores while the weaker binding sites are the outer surfaces of the individual and interior sites located away from the tips of the nanohorns. Results for the effective specific surface area, the kinetics of adsorption, and the isosteric heat of adsorption as a function of sorbent loading will be presented and compared to adsorption results with other sorbates on open carbon nanohorns. This work was supported by the NSF through Grant DMR-1006428.

  2. Membrane Potential Generated by Ion Adsorption

    PubMed Central

    Tamagawa, Hirohisa; Morita, Sachi

    2014-01-01

    It has been widely acknowledged that the Goldman-Hodgkin-Katz (GHK) equation fully explains membrane potential behavior. The fundamental facet of the GHK equation lies in its consideration of permeability of membrane to ions, when the membrane serves as a separator for separating two electrolytic solutions. The GHK equation describes that: variation of membrane permeability to ion in accordance with ion species results in the variation of the membrane potential. However, nonzero potential was observed even across the impermeable membrane (or separator) separating two electrolytic solutions. It gave rise to a question concerning the validity of the GHK equation for explaining the membrane potential generation. In this work, an alternative theory was proposed. It is the adsorption theory. The adsorption theory attributes the membrane potential generation to the ion adsorption onto the membrane (or separator) surface not to the ion passage through the membrane (or separator). The computationally obtained potential behavior based on the adsorption theory was in good agreement with the experimentally observed potential whether the membrane (or separator) was permeable to ions or not. It was strongly speculated that the membrane potential origin could lie primarily in the ion adsorption on the membrane (or separator) rather than the membrane permeability to ions. It might be necessary to reconsider the origin of membrane potential which has been so far believed explicable by the GHK equation. PMID:24957176

  3. Adsorption of phenanthrene on natural snow.

    PubMed

    Domine, Florent; Cincinelli, Alessandra; Bonnaud, Elodie; Martellini, Tania; Picaud, Sylvain

    2007-09-01

    The snowpack is a reservoir for semivolatile organic compounds (SVOCs) and, in particular, for persistent organic pollutants (POPs), which are sequestered in winter and released to the atmosphere or hydrosphere in the spring. Modeling these processes usually assumes that SVOCs are incorporated into the snowpack by adsorption to snow surfaces, but this has never been proven because the specific surface area (SSA) of snow has never been measured together with snow composition. Here we expose natural snow to phenanthrene vapors (one of the more volatile POPs) and measure for the first time both the SSA and the chemical composition of the snow. The results are consistent with an adsorption equilibrium. The measured Henry's law constant is H(Phen)(T) = 2.88 x 10(22) exp(-10660/7) Pa m2 mol(-1), with Tin Kelvin. The adsorption enthalpy is delta H(ads) = -89 +/- 18 kJ mol(-1). We also perform molecular dynamics calculations of phenanthrene adsorption to ice and obtain AHads = -85 +/- 8 kJ mol(-1), close to the experimental value. Results are applied to the adsorption of phenanthrene to the Arctic and subarctic snowpacks. The subarctic snowpack, with a low snow area index (SAI = 1000), is a negligible reservoir of phenanthrene, butthe colder Arctic snowpack, with SAI = 2500, sequesters most of the phenanthrene present in the (snow + boundary layer) system. PMID:17937278

  4. Reconstructed Metabolic Network Models Predict Flux-Level Metabolic Reprogramming in Glioblastoma.

    PubMed

    Özcan, Emrah; Çakır, Tunahan

    2016-01-01

    Developments in genome scale metabolic modeling techniques and omics technologies have enabled the reconstruction of context-specific metabolic models. In this study, glioblastoma multiforme (GBM), one of the most common and aggressive malignant brain tumors, is investigated by mapping GBM gene expression data on the growth-implemented brain specific genome-scale metabolic network, and GBM-specific models are generated. The models are used to calculate metabolic flux distributions in the tumor cells. Metabolic phenotypes predicted by the GBM-specific metabolic models reconstructed in this work reflect the general metabolic reprogramming of GBM, reported both in in-vitro and in-vivo experiments. The computed flux profiles quantitatively predict that major sources of the acetyl-CoA and oxaloacetic acid pool used in TCA cycle are pyruvate dehydrogenase from glycolysis and anaplerotic flux from glutaminolysis, respectively. Also, our results, in accordance with recent studies, predict a contribution of oxidative phosphorylation to ATP pool via a slightly active TCA cycle in addition to the major contributor aerobic glycolysis. We verified our results by using different computational methods that incorporate transcriptome data with genome-scale models and by using different transcriptome datasets. Correct predictions of flux distributions in glycolysis, glutaminolysis, TCA cycle and lipid precursor metabolism validate the reconstructed models for further use in future to simulate more specific metabolic patterns for GBM. PMID:27147948

  5. Reconstructed Metabolic Network Models Predict Flux-Level Metabolic Reprogramming in Glioblastoma

    PubMed Central

    Özcan, Emrah; Çakır, Tunahan

    2016-01-01

    Developments in genome scale metabolic modeling techniques and omics technologies have enabled the reconstruction of context-specific metabolic models. In this study, glioblastoma multiforme (GBM), one of the most common and aggressive malignant brain tumors, is investigated by mapping GBM gene expression data on the growth-implemented brain specific genome-scale metabolic network, and GBM-specific models are generated. The models are used to calculate metabolic flux distributions in the tumor cells. Metabolic phenotypes predicted by the GBM-specific metabolic models reconstructed in this work reflect the general metabolic reprogramming of GBM, reported both in in-vitro and in-vivo experiments. The computed flux profiles quantitatively predict that major sources of the acetyl-CoA and oxaloacetic acid pool used in TCA cycle are pyruvate dehydrogenase from glycolysis and anaplerotic flux from glutaminolysis, respectively. Also, our results, in accordance with recent studies, predict a contribution of oxidative phosphorylation to ATP pool via a slightly active TCA cycle in addition to the major contributor aerobic glycolysis. We verified our results by using different computational methods that incorporate transcriptome data with genome-scale models and by using different transcriptome datasets. Correct predictions of flux distributions in glycolysis, glutaminolysis, TCA cycle and lipid precursor metabolism validate the reconstructed models for further use in future to simulate more specific metabolic patterns for GBM. PMID:27147948

  6. Surface complexation modeling calculation of Pb(II) adsorption onto the calcined diatomite

    NASA Astrophysics Data System (ADS)

    Ma, Shu-Cui; Zhang, Ji-Lin; Sun, De-Hui; Liu, Gui-Xia

    2015-12-01

    Removal of noxious heavy metal ions (e.g. Pb(II)) by surface adsorption of minerals (e.g. diatomite) is an important means in the environmental aqueous pollution control. Thus, it is very essential to understand the surface adsorptive behavior and mechanism. In this work, the Pb(II) apparent surface complexation reaction equilibrium constants on the calcined diatomite and distributions of Pb(II) surface species were investigated through modeling calculations of Pb(II) based on diffuse double layer model (DLM) with three amphoteric sites. Batch experiments were used to study the adsorption of Pb(II) onto the calcined diatomite as a function of pH (3.0-7.0) and different ionic strengths (0.05 and 0.1 mol L-1 NaCl) under ambient atmosphere. Adsorption of Pb(II) can be well described by Freundlich isotherm models. The apparent surface complexation equilibrium constants (log K) were obtained by fitting the batch experimental data using the PEST 13.0 together with PHREEQC 3.1.2 codes and there is good agreement between measured and predicted data. Distribution of Pb(II) surface species on the diatomite calculated by PHREEQC 3.1.2 program indicates that the impurity cations (e.g. Al3+, Fe3+, etc.) in the diatomite play a leading role in the Pb(II) adsorption and dominant formation of complexes and additional electrostatic interaction are the main adsorption mechanism of Pb(II) on the diatomite under weak acidic conditions.

  7. Adsorption of dissolved organics in lake water by aluminum oxide. Effect of molecular weight

    USGS Publications Warehouse

    Davis, J.A.; Gloor, R.

    1981-01-01

    Dissolved organic compounds in a Swiss lake were fractionated into three molecular size classes by gel exclusion chromatography, and adsorption of each fraction on colloidal alumina was studied as a function of pH. Organic compounds with molecular weight (Mr) greater than 1000 formed strong complexes with the alumina surface, but low molecular weight compounds were weakly adsorbed. Electrophoretic mobility measurements indicated that alumina particles suspended in the original lake water were highly negatively charged because of adsorbed organic matter. Most of the adsorbed organic compounds were in the Mr range 1000 < Mr < 3000. Adsorption of these compounds during the treatment of drinking water by alum coagulation may be responsible for the preferential removal of trihalomethane precursors. Adsorption may also influence the molecular-weight distribution of dissolved organic material in lakes. surface, the present work will focus on the influence of molecular size and pH on the adsorption behavior of dissolved organic material of a Swiss lake. From a geochemical point of view, it is important to know the molecular-weight distribution of adsorbed organic matter so that we may better assess its reactivity with trace elements. The study also serves as a first step in quantifying the role of adsorption in the geochemical cycle of organic carbon in lacustrine environments. For water-treatment practice, we need to determine whether molecular weight fractionation occurs during adsorption by aluminum oxide. Such a fractionation could be significant in the light of recent reports that chloroform and other organochlorine compounds are preferentially produced by particular molecular-weight fractions (25-27). ?? 1981 American Chemical Society.

  8. Distribution of radio-labeled N-Acetyl-L-Cysteine in Sprague-Dawley rats and its effect on glutathione metabolism following single and repeat dosing by oral gavage.

    PubMed

    Arfsten, Darryl P; Johnson, Eric W; Wilfong, Erin R; Jung, Anne E; Bobb, Andrew J

    2007-01-01

    The distribution of radio-labeled N-Acetyl-L-Cysteine (NAC) and its impact on glutathione (GSH) metabolism was studied in Sprague-Dawley rats following single and multiple dosing with NAC by oral gavage. Radioactivity associated with administration of (14)C-NAC distributed to most tissues examined within 1 hour of administration with peak radioactivity levels occurring within 1 hour to 4 hours and for a majority of the tissues examined, radioactivity remained elevated for up to 12 hours or more. Administration of a second dose of 1,200 mg/kg NAC + (14)C-NAC 4 hours after the first increased liver, kidney, skin, thymus, spleen, eye, and serum radioactivity significantly beyond levels achieved following 1 dose. Administration of a third dose of 1,200 mg/kg NAC + (14)C-NAC 4 hours after the second dose did not significantly increase tissue radioactivity further except in the skin. GSH concentrations were increased 20% in the skin and 50% in the liver after one dose of 1,200 mg/kg NAC whereas lung and kidney GSH were unaffected. Administration of a second and third dose of 1,200 mg/kg NAC at 4 hours and 8 hours after the first did not increase tissue GSH concentrations above background with the exception that skin GSH levels were elevated to levels similar to those obtained after a single dose of NAC. Glutathione-S-transferase (GST) activity was increased 150% in the kidney and 10% in the liver, decreased 60% in the skin, and had no effect on lung GST activity following a single dose of 1,200 mg/kg NAC. Administration of a second dose of 1,200 mg/kg NAC 4 hours after the first decreased skin GST activity a further 20% whereas kidney GST activity remained elevated at levels similar to those obtained after 1 dose of NAC. Administration of a third dose of NAC 4 hours after the second dose increased liver GST activity significantly as compared to background but did not affect skin, kidney, or lung GST activity. Transient decreases in glutathione reductase (GR) activity

  9. Theoretical description of metabolism using queueing theory.

    PubMed

    Evstigneev, Vladyslav P; Holyavka, Marina G; Khrapatiy, Sergii V; Evstigneev, Maxim P

    2014-09-01

    A theoretical description of the process of metabolism has been developed on the basis of the Pachinko model (see Nicholson and Wilson in Nat Rev Drug Discov 2:668-676, 2003) and the queueing theory. The suggested approach relies on the probabilistic nature of the metabolic events and the Poisson distribution of the incoming flow of substrate molecules. The main focus of the work is an output flow of metabolites or the effectiveness of metabolism process. Two simplest models have been analyzed: short- and long-living complexes of the source molecules with a metabolizing point (Hole) without queuing. It has been concluded that the approach based on queueing theory enables a very broad range of metabolic events to be described theoretically from a single probabilistic point of view. PMID:25142745

  10. Nickel adsorption on single and dual site clay surfaces; Effect of pH and nickel loadings

    NASA Astrophysics Data System (ADS)

    Rajapaksha, A. U.; Vithanage, M. S.; Bandara, A.; Weerasooriya, R.

    2011-12-01

    We examined Ni sorption to single and dual site clays (Al dominant, Fe dominant and both Al and Fe rich sorbents) as adsorbents for removal of Ni from aqueous solutions to (i) compare the capacities, (ii) study the effect of solution pH, (iii) examine the effect of ionic strength on adsorption (iv) determine the adsorption capacity through isotherm models. Gibbsite and goethite were selected as the single site sorbent for Al and Fe while Natural Red Earth (NRE) and laterite, were used as the sorbents with dual sites for this study. The effect of pH on the sorption was studied by adjusting the pH in the range of 4-10. In these experiments, the adsorbent concentration was kept at 5 g/l of solution containing 10 mg/l Ni(II) at 25 0C. Adsorption isotherms were conducted in 0.01 M NaNO3 solution, at pH ≈ 7.5. Both single and dual site clay minerals have exhibited no dependence on ionic strength indicating inner-sphere surface complexation. However, gibbsite demonstrated highest adsorption. Adsorption increased 4-5 folds with the pH increase from 6.0 to 8.5 with maximum adsorption at pH > 8.0. Elemental mapping demonstrated the distribution of elements on the grain including sorbed Ni. These results indicate that > AlO- sites attract Ni better than >FeO- sites. Adsorption shows decrease from gibbsite > laterite > goethite > NRE. Gibbsite showed best fit for the Langmuir equation with r2 around 0.98. This indicates homogeneous adsorption. Maximum adsorption capacity for gibbsite is reported as 5.08x10-4 mol/kg. Therefore, gibbsite and laterite have a good potential to be used to remove nickel from aqueous solutions. Key words : Gibbsite, Geothite, Laterite, Natural Red Earth, Ni sorption

  11. Adsorption of sulfonamides on reduced graphene oxides as affected by pH and dissolved organic matter.

    PubMed

    Liu, Fei-Fei; Zhao, Jian; Wang, Shuguang; Xing, Baoshan

    2016-03-01

    With the significant increase in use and application of graphene and the frequent presence of sulfonamides (SAs) in water environments, their interactions have attracted extensive attention. In this study, adsorption of two selected SAs (sulfapyridine and sulfathiazole) by two reduced graphene oxides (rGO1 and rGO2) was examined as affected by pH and dissolved organic matter (DOM). Adsorption of SAs by rGOs was highly pH-dependent, and adsorption affinity of different SAs species followed the order of SA(0) > SA(+) > SA(-). The contribution of SA(0) to the overall adsorption was greater than its species fraction, implying the importance of the neutral species to adsorption. SAs adsorption isotherms at three selected pHs were in the order of pH 5.0 > pH 1.0 > pH 11.0, which was in accordance with the variation of site energy distribution analysis. Hydrophobic interaction, π-π EDA interaction and electrostatic interaction were the main mechanisms responsible for SAs adsorption by rGOs. Three representative natural DOMs including humic acid (HA), bovine serum albumin (BSA), and sodium alginate together with sodium dodecylbenzenesulfonate (SDBS) as a synthetic DOM were used to investigate their effect on SAs adsorption. The inhibition impact of DOM on SAs adsorption was lower for rGOs compared with carbon nanotubes and graphite, which might be attributed to the higher oxygen contents of rGOs. Also, the suppression effect of DOM generally followed an order of SDBS > HA ≥ BSA > alginate, indicating the importance role of DOM compositions. These results should be important for assessing the fate and transport of graphene and antibiotics in the environment. PMID:26708762

  12. Adsorption Properties of Triethylene Glycol on a Hydrated {101̅4} Calcite Surface and Its Effect on Adsorbed Water.

    PubMed

    Olsen, Richard; Leirvik, Kim N; Kvamme, Bjørn; Kuznetsova, Tatiana

    2015-08-11

    Molecular dynamics (MD) and Born-Oppenheimer MD (BOMD) simulations were employed to investigate adsorption of aqueous triethylene glycol (TEG) on a hydrated {101̅4} calcite surface at 298 K. We analyzed the orientation of TEG adsorbed on calcite, as well as the impact of TEG on the water density and adsorption free energy. The adsorption energies of TEG, free energy profiles for TEG, details of hydrogen bonding between water and adsorbed TEG, and dihedral angle distribution of adsorbed TEG were estimated. We found that while the first layer of water was mostly unaffected by the presence of adsorbed TEG, the density of the second water layer was decreased by 71% at 75% surface coverage of TEG. TEG primarily attached to the calcite surface via two adjacent adsorption sites. Hydrogen bonds between water and adsorbed TEG in the second layer almost exclusively involved the hydroxyl oxygen of TEG. The adsorption energy of TEG on calcite in a vacuum environment calculated by classical MD amounted to 217 kJ/mol, which agreed very well with estimates found by using BOMD. Adsorption on hydrated calcite yielded a drastically lower value of 33 kJ/mol, with the corresponding adsorption free energy of 55.3 kJ/mol, giving an entropy increase of 22.3 kJ/mol due to adsorption. We found that the presence of TEG resulted in a decreased magnitude of the adsorption free energy of water, thus decreasing the calcite wettability. This effect can have a profound effect on oil and gas reservoir properties and must be carefully considered when evaluating the risk of hydrate nucleation. PMID:26161580

  13. Adsorption of HO(x) on aerosol surfaces - Implications for the atmosphere of Mars

    NASA Technical Reports Server (NTRS)

    Anbar, A. D.; Leu, M.-T.; Nair, H. A.; Yung, Y. L.

    1993-01-01

    The potential impact of heterogeneous chemistry on the abundance and distribution of HO(x) in the Martian atmosphere is investigated using observational data on dust and ice aerosol distributions combined with an updated photochemical model. Critical parameters include the altitude distributions of aerosols and the surface loss coefficients of HO2 on dust and ice in the lower atmosphere and of H on ice above 40 km. Results of calculations indicate that adsorption of HO2 on dust, or ice near 30 km, can deplete OH abundances in the lower atmosphere by 10 percent or more and that the adsorption of H on ice at 50 km can result in even larger OH depletions (this effect is localized to altitudes greater than 40 km, where CO oxidation is relatively unimportant).

  14. Novel nano bearings constructed by physical adsorption

    PubMed Central

    Zhang, Yongbin

    2015-01-01

    The paper proposes a novel nano bearing formed by the physical adsorption of the confined fluid to the solid wall. The bearing is formed between two parallel smooth solid plane walls sliding against one another, where conventional hydrodynamic lubrication theory predicted no lubricating effect. In this bearing, the stationary solid wall is divided into two subzones which respectively have different interaction strengths with the lubricating fluid. It leads to different physical adsorption and slip properties of the lubricating fluid at the stationary solid wall respectively in these two subzones. It was found that a significant load-carrying capacity of the bearing can be generated for low lubricating film thicknesses, because of the strong physical adsorption and non-continuum effects of the lubricating film. PMID:26412488

  15. Novel nano bearings constructed by physical adsorption.

    PubMed

    Zhang, Yongbin

    2015-01-01

    The paper proposes a novel nano bearing formed by the physical adsorption of the confined fluid to the solid wall. The bearing is formed between two parallel smooth solid plane walls sliding against one another, where conventional hydrodynamic lubrication theory predicted no lubricating effect. In this bearing, the stationary solid wall is divided into two subzones which respectively have different interaction strengths with the lubricating fluid. It leads to different physical adsorption and slip properties of the lubricating fluid at the stationary solid wall respectively in these two subzones. It was found that a significant load-carrying capacity of the bearing can be generated for low lubricating film thicknesses, because of the strong physical adsorption and non-continuum effects of the lubricating film. PMID:26412488

  16. Modeling tailed bacteriophage adsorption: Insight into mechanisms.

    PubMed

    Storms, Zachary J; Sauvageau, Dominic

    2015-11-01

    The process of a bacteriophage attaching to its host cell is a combination of physical diffusion, biochemical surface interactions, and reaction-induced conformational changes in receptor proteins. Local variations in the physico-chemical properties of the medium, the phage׳s mode of action, and the physiology of the host cell also all influence adsorption kinetics. These characteristics can affect a specific phage׳s binding capabilities and the susceptibility of the host cell to phage attack. Despite the complexity of this process, describing adsorption kinetics of a population of bacteriophages binding to a culture of cells has been accomplished with relatively simple equations governed by the laws of mass-action. Many permutations and modifications to the basic set of reactions have been suggested through the years. While no single solution emerges as a universal answer, this review provides the fundamentals of current phage adsorption modeling and will guide researchers in the selection of valid, appropriate models. PMID:26331682

  17. Adsorption of phenolic compounds on fly ash

    SciTech Connect

    Akgerman, A.; Zardkoohi, M.

    1996-03-01

    Adsorption isotherms for adsorption of phenol, 3-chlorophenol, and 2,4-dichlorophenol from water onto fly ash were determined. These isotherms were modeled by the Freundlich isotherm. The fly ash adsorbed 67, 20, and 22 mg/g for phenol, chlorophenol, and 2,4-dichlorophenol, respectively, for the highest water phase concentrations used. The affinity of phenolic compounds for fly ash is above the expected amount corresponding to a monolayer coverage considering that the surface area of fly ash is only 1.87 m{sup 2}/g. The isotherms for contaminants studied were unfavorable, indicating that adsorption becomes progressively easier as more solutes are taken up. Phenol displayed a much higher affinity for fly ash than 3-chlorophenol and 2,4-dichlorophenol.

  18. Adsorption of tetrahydrothiophene (THT) onto soils

    NASA Astrophysics Data System (ADS)

    Juriga, Martin; Kubinec, Róbert; Rajzinger, Ján; Jelemenský, Karol; Gužela, Štefan

    2014-08-01

    Adsorption is one of the major industrial separation technique nowadays. Although adsorption is most commonly used as a separation method, in some cases cause harmful and undesirable effects such as capture odorant from natural gas onto soil. In the event of an accident, the gas can leak from pipes in two ways - either directly into the surrounding air, or the soil where the odorant can be mostly absorbed depending of type of soil, water content and temperature. Design of experimental apparatus for measurement of breakthrough curves is studied in detail. Alternative arrangement of experimental apparatus, calibration of measuring devices, method of measurement and processing the data are narrowly discussed. Moreover, experimental measurements of breakthrough curves are presented. The actual measurement was made to identify the equilibrium adsorption capacity of THT (tetrahydrothiophene) onto soils. Experimental data were evaluated using Linear, Freundlich, Langmuir and Koble-Corrigan model.

  19. Novel nano bearings constructed by physical adsorption

    NASA Astrophysics Data System (ADS)

    Zhang, Yongbin

    2015-09-01

    The paper proposes a novel nano bearing formed by the physical adsorption of the confined fluid to the solid wall. The bearing is formed between two parallel smooth solid plane walls sliding against one another, where conventional hydrodynamic lubrication theory predicted no lubricating effect. In this bearing, the stationary solid wall is divided into two subzones which respectively have different interaction strengths with the lubricating fluid. It leads to different physical adsorption and slip properties of the lubricating fluid at the stationary solid wall respectively in these two subzones. It was found that a significant load-carrying capacity of the bearing can be generated for low lubricating film thicknesses, because of the strong physical adsorption and non-continuum effects of the lubricating film.

  20. Adsorption--from theory to practice.

    PubMed

    Dabrowski, A

    2001-10-01

    Adsorption at various interfaces has concerned scientists since the beginning of this century. This phenomenon underlies a number of extremely important processes of utilitarian significance. The technological, environmental and biological importance of adsorption can never be in doubt. Its practical applications in industry and environmental protection are of paramount importance. The adsorption of substrates is the first stage in many catalytic processes. The methods for separation of mixtures on a laboratory and on an industrial scale are increasingly based on utilising the change in concentration of components at the interface. Moreover, such vital problems as purification of water, sewages, air and soil are involved here too. On the other hand, many areas in which technological innovation has covered adsorption phenomena have been expanded more through art and craft than through science. A basic understanding of the scientific principles is far behind; in part because the study of interfaces requires extremely careful experimentation if meaningful and reproducible results are to be obtained. In recent years, however, considerable effort has been increasingly directed toward closing the gap between theory and practice. Crucial progress in theoretical description of the adsorption has been achieved, mainly through the development of new theoretical approaches formulated on a molecular level, by means of computer simulation methods and owing to new techniques which examine surface layers or interfacial regions. Moreover, during the last 15 years new classes of solid adsorbents have been developed, such as activated carbon fibres and carbon molecular sieves, fullerenes and heterofullerenes, microporous glasses and nanoporous--both carbonaceous and inorganic--materials. Nanostructured solids are very popular in science and technology and have gained extreme interest due to their sorption, catalytic, magnetic, optical and thermal properties. Although the development

  1. Porous silicon functionalization for possible arsenic adsorption

    PubMed Central

    2014-01-01

    Thiol-functionalized porous silicon (PS) monolayer was evaluated for its possible application in As (III) adsorption. Dimercaptosuccinic acid (DMSA) attached to mesoporous silicon via amide bond linkages was used as a chelate for As (III). Two different aminosilanes namely 3-(aminopropyl) triethoxysilane (APTES) and 3-aminopropyl (diethoxy)-methylsilane (APDEMS) were tested as linkers to evaluate the relative response for DMSA attachment. The aminosilane-modified PS samples were attached to DMSA by wet impregnation followed by the adsorption of As (III). Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) have been used to identify the functional groups and to estimate the As (III) content, respectively. FTIR spectroscopy confirmed the covalent bonding of DMSA with amide and R-COOH groups on the nanostructured porous surface. XPS confirms the preferred arsenic adsorption on the surface of PS/DMSA samples as compared to the aminosilane-modified and bare PS substrates. PMID:25249826

  2. Heavy metal adsorption by sulphide mineral surfaces

    NASA Astrophysics Data System (ADS)

    Jean, Gilles E.; Bancroft, G. Michael

    1986-07-01

    The adsorption of aqueous Hg 2+, Pb 2+, Zn 2+ and Cd 2+ complexes on a variety of sulphide minerals has been studied as a function of the solution pH and also as a function of the nature of the ligands in solution. Sulphide minerals are excellent scavengers for these heavy metals. The adsorption is strongly pH dependent, i.e. there is a critical pH at which the adsorption increases dramatically. The pH dependence is related to the hydrolysis of the metal ions. Indirect evidence suggests that the hydrolyzed species are adsorbed directly on the sulphide groups, probably as a monolayer. The results also suggest the presence of MCI n2- n species physisorbed on the adsorbed monolayer. A positive identification of the adsorbed species was not possible using ESCA/XPS.

  3. Adsorption of Sr by immobilized microorganisms

    SciTech Connect

    Watson, J.S.; Scott, C.D.; Faison, B.D.

    1988-01-01

    Wastewaters from numerous industrial and laboratory operations can contain toxic or undesirable components such as metal ions, which must be removed before discharge to surface waters. Adsorption processes that have high removal efficiencies are attractive methods for removing such contaminants. For economic operations, it is desirable to have an adsorbent that is selective for the metal contaminant of interest, has high capacity for the contaminant, has rapid adsorption kinetics, can be economically produced, and can be regenerated to a concentrated waste product or decomposed to a low-volume waste. Selected microorganisms are potentially useful adsorbents for these applications because they can be inexpensive, have high selectivities, and have high capacities for adsorption of many heavy metals, which are often problems in a variety of industries. A laboratory-scale packed column containing microbial cells immobilized within a gelatin matrix has been prepared, and its application to removal of Sr from a simulated wastewater is described. 6 refs., 2 figs., 3 tabs.

  4. The Adsorption of Polyelectrolytes on Hydroxyapatite Crystals.

    PubMed

    Tsortos; Nancollas

    1999-01-01

    The adsorption of two polyelectrolytes, poly-L-Glutamate and poly-L-Aspartate, on hydroxyapatite (HAP) crystals was studied both experimentally and theoretically. Langmuir adsorption isotherms were obtained for both these molecules, with binding constants K = 6 x 10(6) and 3 x 10(6) M-1, respectively, at 37.0 degreesC, pH 7.4, and 0.15 M ionic strength. A theoretical analysis of the data, based on a model proposed by Hesselink, suggested a "train-loop" type of adsorption with non-electrostatic energy terms 3.51 and 4.76 (kT) for poly-L-Glu and poly-L-Asp, respectively. Copyright 1999 Academic Press. PMID:9878142

  5. Adsorption kinetics of silicic acid on akaganeite.

    PubMed

    Naren, Gaowa; Ohashi, Hironori; Okaue, Yoshihiro; Yokoyama, Takushi

    2013-06-01

    As part of a series of studies on the interaction between ferric ions and silicic acid in the hydrosphere, the adsorption of silicic acid on akaganeite was investigated kinetically at various pH values. The adsorption of silicic acid increased with increasing pH over an initial pH range of 4-11.5. In the kinetic experiment, the Cl(-) was released from akaganeite much faster than silicic acid was adsorbed. From this result, we concluded that chloride ions bound on the surface of akaganeite are released and Fe-OH or Fe-O(-) sites are formed, which then acts as an adsorption site for silicic acid. The uptake mechanism of silicic acid by akaganeite is significantly different from that by schwertmannite, despite the presence of the same tunnel structure. PMID:23538050

  6. Dihydroxyacetone metabolism in Haloferax volcanii

    PubMed Central

    Ouellette, Matthew; Makkay, Andrea M.; Papke, R. Thane

    2013-01-01

    Dihydroxyacetone (DHA) is a ketose sugar that can be produced by oxidizing glycerol. DHA in the environment is taken up and phosphorylated to DHA-phosphate by glycerol kinase or DHA kinase. In hypersaline environments, it is hypothesized that DHA is produced as an overflow product from glycerol utilization by organisms such as Salinibacter ruber. Previous research has demonstrated that the halobacterial species Haloquadratum walsbyi can use DHA as a carbon source, and putative DHA kinase genes were hypothesized to be involved in this process. However, DHA metabolism has not been demonstrated in other halobacterial species, and the role of the DHA kinase genes was not confirmed. In this study, we examined the metabolism of DHA in Haloferax volcanii because putative DHA kinase genes were annotated in its genome, and it has an established genetic system to assay growth of mutant knockouts. Experiments in which Hfx. volcanii was grown on DHA as the sole carbon source demonstrated growth, and that it is concentration dependent. Three annotated DHA kinase genes (HVO_1544, HVO_1545, and HVO_1546), which are homologous to the putative DHA kinase genes present in Hqm. walsbyi, as well as the glycerol kinase gene (HVO_1541), were deleted to examine the effect of these genes on the growth of Hfx. volcanii on DHA. Experiments demonstrated that the DHA kinase deletion mutant exhibited diminished, but not absence of growth on DHA compared to the parent strain. Deletion of the glycerol kinase gene also reduced growth on DHA, and did so more than deletion of the DHA kinase. The results indicate that Hfx. volcanii can metabolize DHA and that DHA kinase plays a role in this metabolism. However, the glycerol kinase appears to be the primary enzyme involved in this process. BLASTp analyses demonstrate that the DHA kinase genes are patchily distributed among the Halobacteria, whereas the glycerol kinase gene is widely distributed, suggesting a widespread capability for DHA metabolism

  7. Temporal Expression-based Analysis of Metabolism

    PubMed Central

    Segrè, Daniel

    2012-01-01

    Metabolic flux is frequently rerouted through cellular metabolism in response to dynamic changes in the intra- and extra-cellular environment. Capturing the mechanisms underlying these metabolic transitions in quantitative and predictive models is a prominent challenge in systems biology. Progress in this regard has been made by integrating high-throughput gene expression data into genome-scale stoichiometric models of metabolism. Here, we extend previous approaches to perform a Temporal Expression-based Analysis of Metabolism (TEAM). We apply TEAM to understanding the complex metabolic dynamics of the respiratorily versatile bacterium Shewanella oneidensis grown under aerobic, lactate-limited conditions. TEAM predicts temporal metabolic flux distributions using time-series gene expression data. Increased predictive power is achieved by supplementing these data with a large reference compendium of gene expression, which allows us to take into account the unique character of the distribution of expression of each individual gene. We further propose a straightforward method for studying the sensitivity of TEAM to changes in its fundamental free threshold parameter θ, and reveal that discrete zones of distinct metabolic behavior arise as this parameter is changed. By comparing the qualitative characteristics of these zones to additional experimental data, we are able to constrain the range of θ to a small, well-defined interval. In parallel, the sensitivity analysis reveals the inherently difficult nature of dynamic metabolic flux modeling: small errors early in the simulation propagate to relatively large changes later in the simulation. We expect that handling such “history-dependent” sensitivities will be a major challenge in the future development of dynamic metabolic-modeling techniques. PMID:23209390

  8. Effect of particle adsorption rates on the disproportionation process in pickering stabilised bubbles.

    PubMed

    Ettelaie, Rammile; Murray, Brent

    2014-05-28

    The degree of shrinkage of particle stabilised bubbles of various sizes, in a polydisperse bubble dispersion, has been investigated in the light of the finite adsorption times for the particles and the disproportionation kinetics of the bubbles. For the case where the system contains an abundance of particles we find a threshold radius, above which bubbles are stabilised without any significant reduction in their size. Bubbles with an initial radius below this threshold on the other hand undergo a large degree of shrinkage prior to stabilisation. As the ratio of the available particles to the bubbles is reduced, it is shown that the final bubble size, for the larger bubbles in the distribution, becomes increasingly governed by the number of particles, rather than their adsorption time per se. For systems with "adsorption controlled" shrinkage ratio, the final bubble distribution is found to be wider than the initial one, while for a "particle number controlled" case it is actually narrower. Starting from a unimodal bubble size distribution, we predict that at intermediate times, prior to the full stabilisation of all bubbles, the distribution breaks up into a bimodal one. However, the effect is transient and a unimodal final bubble size distribution is recovered, when all the bubbles are stabilised by the particles. PMID:24880317

  9. Development of Pressure Swing Adsorption Technology for Spacesuit Carbon Dioxide and Humidity Removal

    NASA Technical Reports Server (NTRS)

    Papale, William; Paul, Heather; Thomas, Gretchen

    2006-01-01

    Metabolically produced carbon dioxide (CO2) removal in spacesuit applications has traditionally been accomplished utilizing non-regenerative Lithium Hydroxide (LiOH) canisters. In recent years, regenerative Metal Oxide (MetOx) has been developed to replace the Extravehicular Mobility Unity (EMU) LiOH canister for extravehicular activity (EVA) missions in micro-gravity, however, MetOx may carry a significant weight burden for potential use in future Lunar or planetary EVA exploration missions. Additionally, both of these methods of CO2 removal have a finite capacity sized for the particular mission profile. Metabolically produced water vapor removal in spacesuits has historically been accomplished by a condensing heat exchanger within the ventilation process loop of the suit life support system. Advancements in solid amine technology employed in a pressure swing adsorption system have led to the possibility of combining both the CO2 and humidity control requirements into a single, lightweight device. Because the pressure swing adsorption system is regenerated to space vacuum or by an inert purge stream, the duration of an EVA mission may be extended significantly over currently employed technologies, while markedly reducing the overall subsystem weight compared to the combined weight of the condensing heat exchanger and current regenerative CO2 removal technology. This paper will provide and overview of ongoing development efforts evaluating the subsystem size required to manage anticipated metabolic CO2 and water vapor generation rates in a spacesuit environment.

  10. Protein adsorption to multi-component glasses

    NASA Astrophysics Data System (ADS)

    Hall, Matthew Micah

    2003-07-01

    The adsorption of human serum albumin (HSA) to sodium silicate, soda lime silicate (SLS), and sodium aluminosilicate (SAS) glass microspheres was investigated using sodiumdodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in conjunction with a colloidal silver stain for visualization. The 30 Na2O·70 SiO2 composition could not be evaluated due to an apparent chemical interference that occurred during silver staining. This inhibitory effect was attributed to the extensive corrosion that occurred during the protein elution and caused an elevation in the pH of the solution. The remaining glass compositions were sufficiently durable for further study. The HSA adsorption capacity of SLS glass microspheres containing 70 and 80 mol% SiO2 increased as CaO was substituted for Na2O. An abrupt decrease in the HSA adsorption capacity was observed for SLS glasses containing 60 mol% SiO2. A similar trend was observed for the SAS glass microspheres, although the SAS glasses adsorbed less HSA than the SLS glasses containing equivalent molar percentages of SiO2. The initial increase in HSA adsorption capacity for SLS and SAS glasses containing 70 and 80 MOM SiO2 was attributed to the introduction of positive charges into the glass surfaces via Ca2+ and Al3+ cations. The decrease in HSA adsorption capacity for SLS and SAS glasses containing 60 mol% SiO2 may be due to an enhanced affinity between the glasses and HSA, resulting in a "flattened" conformation that limits the total accessible area for adsorption.

  11. Surface shear rheology of saponin adsorption layers.

    PubMed

    Golemanov, Konstantin; Tcholakova, Slavka; Denkov, Nikolai; Pelan, Edward; Stoyanov, Simeon D

    2012-08-21

    Saponins are a wide class of natural surfactants, with molecules containing a rigid hydrophobic group (triterpenoid or steroid), connected via glycoside bonds to hydrophilic oligosaccharide chains. These surfactants are very good foam stabiliziers and emulsifiers, and show a range of nontrivial biological activities. The molecular mechanisms behind these unusual properties are unknown, and, therefore, the saponins have attracted significant research interest in recent years. In our previous study (Stanimirova et al. Langmuir 2011, 27, 12486-12498), we showed that the triterpenoid saponins extracted from Quillaja saponaria plant (Quillaja saponins) formed adsorption layers with unusually high surface dilatational elasticity, 280 ± 30 mN/m. In this Article, we study the shear rheological properties of the adsorption layers of Quillaja saponins. In addition, we study the surface shear rheological properties of Yucca saponins, which are of steroid type. The experimental results show that the adsorption layers of Yucca saponins exhibit purely viscous rheological response, even at the lowest shear stress applied, whereas the adsorption layers of Quillaja saponins behave like a viscoelastic two-dimensional body. For Quillaja saponins, a single master curve describes the data for the viscoelastic creep compliance versus deformation time, up to a certain critical value of the applied shear stress. Above this value, the layer compliance increases, and the adsorption layers eventually transform into viscous ones. The experimental creep-recovery curves for the viscoelastic layers are fitted very well by compound Voigt rheological model. The obtained results are discussed from the viewpoint of the layer structure and the possible molecular mechanisms, governing the rheological response of the saponin adsorption layers. PMID:22830458

  12. Adsorption of Gases on Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Mbaye, Mamadou Thiao

    This research focus in studying the interaction between various classical and quantum gases with novel carbon nanostructures, mainly carbon nanotubes (CNTs). Since their discovery by the Japanese physicist Sumio Iijima [1] carbon nanotubes have, experimentally and theoretically, been subjected to many scientific investigation. Studies of adsorption on CNTs are particularly directed toward their better usage in gas storage, gas separation, catalyst, drug delivery, and water purification. We explore the adsorption of different gases entrapped in a single, double, or multi-bundles of CNTs using computer simulations. The first system we investigate consists of Ar and Kr films adsorbed on zigzag or armchair nanotubes. Our simulations revealed that Kr atoms on intermediate size zigzag NTs undergo two phase transitions: A liquid-vapor (L→V), and liquid-commensurate (L→CS) with a fractional coverage of one Kr atoms adsorbed for every four carbon atoms. For Ar on zigzag and armchair NTs, the only transition observed is a L→V. In the second problem, we explore the adsorption of CO2 molecules in a nanotube bundle and calculate the isosteric heat of adsorption of the entrapped molecules within the groove. We observed that the lower the temperature, the higher the isosteric of adsorption. Last, we investigate the adsorption of hydrogen, Helium, and Neon gases on the groove site of two parallel nanotubes. At low temperature, the transverse motion on the plane perpendicular to the tubes' axis is frozen out and as a consequence, the heat capacity is reduced to 1/2. At high temperature, the atoms gain more degree of freedom and as a consequence the heat capacity is 5/2.

  13. Database for protein adsorption: update on developments

    NASA Astrophysics Data System (ADS)

    Paszek, Ewa; Vasina, Elena N.; Nicolau, Dan V.

    2008-12-01

    Protein adsorption at solid-liquid interfaces is critical to many applications, including biomaterials, protein microarrays and lab-on-a-chip devices. Despite this general interest, and a large amount of research in the last half a century, protein adsorption cannot be predicted with an engineering level, design-orientated accuracy. Here we describe a Biomolecular Adsorption Database (BAD), freely available online, which archives the published protein adsorption data. Piecewise linear regression with breakpoint applied to the data in the BAD suggests that the input variables to protein adsorption, i.e., protein concentration in solution; protein descriptors derived from primary structure (number of residues, protein hydrophobicity and spread of amino acid hydrophobicity, isoelectric point); surface descriptors (contact angle); and fluid environment descriptors (pH, ionic strength), correlate well with the output variable - the protein concentration on the surface. Furthermore, neural network analysis revealed that the size of the BAD makes it sufficiently representative, with a neural network-based predictive error of 5% or less. Interestingly, a consistently better fit is obtained if the BAD is divided into two separate subsets representing protein adsorption on hydrophilic and hydrophobic surfaces. Based on these findings, selected entries from the BAD have been used to construct neural network-based estimation routines, which predict the amount of adsorbed protein, the thickness of the absorbed layer and the surface tension of the proteincovered surface. While the BAD is of general interest, the prediction of the thickness and the surface tension of the protein-covered layers are of particular relevance to the design of microfluidics devices.

  14. Adsorption behavior of copper and zinc in soils: Influence of pH on adsorption characteristics

    SciTech Connect

    Msaky, J.J. ); Calvet, R. )

    1990-08-01

    The authors studied adsorption of copper and zinc on three different soils: a brown silty soil, an Oxisol, and a Podzol. They determined the amounts adsorbed and the shapes of adsorption isotherms as a function of the pH of the adsorbing medium at a constant ionic strength. The adsorbed amount-pH relationship depended strongly on the natures of the metallic cation and of the soil. The pH greatly influenced the characteristics of adsorption isotherms. They based interpretation on the variations with the pH of both adsorbent affinity for the metal in relation to the surface electric charge and chemical speciation in solution. The adsorption mechanism in the Oxisol probably involves monohydroxylated cations but is more determined by bivalent cations in the brown silty soil and the Podzol. From a general point of view, adsorption of copper and zinc cannot be represented with a single adsorption constant, but should be described by adsorption isotherms obtained at various pH values.

  15. Adsorptive Removal and Adsorption Kinetics of Fluoroquinolone by Nano-Hydroxyapatite

    PubMed Central

    Chen, Yajun; Lan, Tao; Duan, Lunchao; Wang, Fenghe; Zhao, Bin; Zhang, Shengtian; Wei, Wei

    2015-01-01

    Various kinds of antibiotics, especially fluoroquinolone antibiotics (FQs) have been widely used for the therapy of infectious diseases in human and livestock. For their poorly absorbed by living organisms, large-scale misuse or abuse of FQs will foster drug resistance among pathogenic bacteria, as well as a variety of environmental problems when they were released in the environment. In this work, the adsorption properties of two FQs, namely norfloxacin (NOR) and ciprofloxacin (CIP), by nano-hydroxyapatite (n-HAP) were studied by batch adsorption experiments. The adsorption curves of FQs by n-HAP were simulated by Langmuir and Freundlich isotherms. The results shown that NOR and CIP can be adsorbed effectively by the adsorbent of n-HAP, and the adsorption capacity of FQs increase with increasing dosage of n-HAP. The optimum dosage of n-HAP for FQs removal was 20 g·L-1, in which the removal efficiencies is 51.6% and 47.3%, and an adsorption equilibrium time is 20 min. The maximum removal efficiency occurred when pH is 6 for both FQs. The adsorption isotherm of FQs fits well for both Langmuir and Freundlich equations. The adsorption of both FQs by n-HAP follows second-order kinetics. PMID:26698573