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Sample records for adsorption distribution metabolism

  1. Numerical estimation of adsorption energy distributions from adsorption isotherm data with the expectation-maximization method

    SciTech Connect

    Stanley, B.J.; Guiochon, G. |

    1993-08-01

    The expectation-maximization (EM) method of parameter estimation is used to calculate adsorption energy distributions of molecular probes from their adsorption isotherms. EM does not require prior knowledge of the distribution function or the isotherm, requires no smoothing of the isotherm data, and converges with high stability towards the maximum-likelihood estimate. The method is therefore robust and accurate at high iteration numbers. The EM algorithm is tested with simulated energy distributions corresponding to unimodal Gaussian, bimodal Gaussian, Poisson distributions, and the distributions resulting from Misra isotherms. Theoretical isotherms are generated from these distributions using the Langmuir model, and then chromatographic band profiles are computed using the ideal model of chromatography. Noise is then introduced in the theoretical band profiles comparable to those observed experimentally. The isotherm is then calculated using the elution-by-characteristic points method. The energy distribution given by the EM method is compared to the original one. Results are contrasted to those obtained with the House and Jaycock algorithm HILDA, and shown to be superior in terms of robustness, accuracy, and information theory. The effect of undersampling of the high-pressure/low-energy region of the adsorption is reported and discussed for the EM algorithm, as well as the effect of signal-to-noise ratio on the degree of heterogeneity that may be estimated experimentally.

  2. 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.

  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. 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.

  5. Effect of charge distribution on RDX adsorption in IRMOF-10

    SciTech Connect

    Xiong, Ruichang; Keffer, David J.; Fuentes-Cabrera, Miguel A; Nicholson, Don M; Michalkova, Andrea; Petrova, Tetyana; Leszczynski, Jerzy; Odbadrakh, Khorgolkhuu; Doss, Bryant; Lewis, James

    2010-01-01

    Quantum mechanical (QM) calculations, classical grand canonical Monte Carlo (GCMC) simulations, and classical molecular dynamics (MD) simulations are performed to test the effect of charge distribution on hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) adsorption and diffusion in IRMOF-10. Several different methods for mapping QM electron distributions onto atomic point charges are explored, including the electrostatic potential (ESP) method, Mulliken population analysis, L{sub 0}wdin population analysis, and natural bond orbital analysis. Classical GCMC and MD simulations of RDX in IRMOF-10 are performed using 15 combinations of charge sources of RDX and IRMOF-10. As the charge distributions vary, interaction potential energies, the adsorption loading, and the self-diffusivities are significantly different. None of the 15 combinations are able to quantitatively capture the dependence of the energy of adsorption on local configuration of RDX as observed in the QM calculations. We observe changes in the charge distributions of RDX and IRMOF-10 with the introduction of an RDX molecule into the cage. We also observe a large dispersion contribution to the interaction energy from QM calculations that is not reproduced in the classical simulations, indicating that the source of discrepancy may not lie exclusively with the assignment of charges.

  6. 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.

  7. Anisotropic adsorption and distribution of immobilized carboxyl on nanodiamond

    NASA Astrophysics Data System (ADS)

    Lai, Lin; Barnard, Amanda S.

    2014-11-01

    Stable and predictable functionalization of nanodiamond with carboxyl is an important first step in loading these materials with therapeutic agents, and the conjugation with proteins, cytochrome, antigen, and DNA. By creating a map of the adsorption strength of COOH, OH, O and H with atomic level resolution across the entire surface of an experimentally realistic nanodiamond, we have shown how the distribution is highly anisotropic, and depends on surface reconstructions, facet orientation, and ultimately the shape. This provides useful insights into how the structure of nanodiamond impacts the formation of COOH surface monolayers, and suggests that efforts to separate nanodiamonds by shape would be highly beneficial in the development of drug delivery vehicles targeted to specific treatment regimes.Stable and predictable functionalization of nanodiamond with carboxyl is an important first step in loading these materials with therapeutic agents, and the conjugation with proteins, cytochrome, antigen, and DNA. By creating a map of the adsorption strength of COOH, OH, O and H with atomic level resolution across the entire surface of an experimentally realistic nanodiamond, we have shown how the distribution is highly anisotropic, and depends on surface reconstructions, facet orientation, and ultimately the shape. This provides useful insights into how the structure of nanodiamond impacts the formation of COOH surface monolayers, and suggests that efforts to separate nanodiamonds by shape would be highly beneficial in the development of drug delivery vehicles targeted to specific treatment regimes. Electronic supplementary information (ESI) available: Coordinates of the fully replaced diamond nanoparticle used in this study (in standard xyz format), and images of all of the relaxed ND-COOH binding configurations. See DOI: 10.1039/c4nr05363j

  8. Strontium Adsorption and Desorption Reactions in Model Drinking Water Distribution Systems

    DTIC Science & Technology

    2014-02-04

    RESPONSIBLE PERSON 19b. TELEPHONE NUMBER (Include area code) 11-04-2014 Journal Article Strontium adsorption and desorption reactions in model... strontium (Sr2+) adsorption to and desorption from iron corrosion products were examined in two model drinking water distribution systems (DWDS...used to control Sr2; desorption. calcium carbonate; drinking water distribution system; α-FeOOH; iron; strontium ; XANES Unclassified

  9. Adsorption energy distribution of carbon tetrachloride on carbon nanofiber arrays prepared by template synthesis

    NASA Astrophysics Data System (ADS)

    Wu, Chi-Hsin; Shr, Jin-Fang; Wu, Chu-Fu; Hsieh, Chien-Te

    2008-02-01

    The influence of pore size distribution on adsorption energy distributions (AEDs) of aligned carbon nanofiber (CNF) arrays in vapor phase was conducted in the present study. A template-assisted synthesis was employed to fabricate aligned CNF arrays with different pore size distributions (PSDs). Adsorption isotherms of CCl 4 onto the CNF arrays were investigated within an entire pressure of 0.05-0.18 atm at 30 °C. The adsorptive surface coverage was found to decrease with the average pore size, indicating the presence of heterogeneity for gas adsorption. An AED model was postulated to describe the heterogeneous surface consisting of numerous surface pitchwises that obey a localized Langmuir model. It was found that all CNF arrays exhibit a similar Gaussian-type AED, in where the peak adsorption energy shifts to a higher energy with decreasing the pore size of CNFs. This finding can be ascribed to a fact that micropores are major providers of adsorption sites, whereas in mesopores only weaker adsorption is observed, thus resulting in the shift of energy distribution. An excellent prediction to the adsorption isotherms of CCl 4 by the AED model indicates that the PSD of CNFs acts a crucial factor in affecting the adsorptive coverage.

  10. Matching isotopic distributions from metabolically labeled samples

    PubMed Central

    McIlwain, Sean; Page, David; Huttlin, Edward L.; Sussman, Michael R.

    2008-01-01

    Motivation: In recent years stable isotopic labeling has become a standard approach for quantitative proteomic analyses. Among the many available isotopic labeling strategies, metabolic labeling is attractive for the excellent internal control it provides. However, analysis of data from metabolic labeling experiments can be complicated because the spacing between labeled and unlabeled forms of each peptide depends on its sequence, and is thus variable from analyte to analyte. As a result, one generally needs to know the sequence of a peptide to identify its matching isotopic distributions in an automated fashion. In some experimental situations it would be necessary or desirable to match pairs of labeled and unlabeled peaks from peptides of unknown sequence. This article addresses this largely overlooked problem in the analysis of quantitative mass spectrometry data by presenting an algorithm that not only identifies isotopic distributions within a mass spectrum, but also annotates matches between natural abundance light isotopic distributions and their metabolically labeled counterparts. This algorithm is designed in two stages: first we annotate the isotopic peaks using a modified version of the IDM algorithm described last year; then we use a probabilistic classifier that is supplemented by dynamic programming to find the metabolically labeled matched isotopic pairs. Such a method is needed for high-throughput quantitative proteomic metabolomic experiments measured via mass spectrometry. Results: The primary result of this article is that the dynamic programming approach performs well given perfect isotopic distribution annotations. Our algorithm achieves a true positive rate of 99% and a false positive rate of 1% using perfect isotopic distribution annotations. When the isotopic distributions are annotated given ‘expert’ selected peaks, the same algorithm gets a true positive rate of 77% and a false positive rate of 1%. Finally, when annotating using

  11. 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.

  12. Cesium adsorption and distribution onto crushed granite under different physicochemical conditions.

    PubMed

    Tsai, Shih-Chin; Wang, Tsing-Hai; Li, Ming-Hsu; Wei, Yuan-Yaw; Teng, Shi-Ping

    2009-01-30

    The adsorption of cesium onto crushed granite was investigated under different physicochemical conditions including contact time, Cs loading, ionic strength and temperature. In addition, the distribution of adsorbed Cs was examined by X-ray diffraction (XRD) and EDS mapping techniques. The results showed that Cs adsorption to crushed granite behaved as a first-order reaction with nice regression coefficients (R(2) > or = 0.971). Both Freundlich and Langmuir models were applicable to describe the adsorption. The maximum sorption capacity determined by Langmuir model was 80 micromol g(-1) at 25 degrees C and 10 micromol g(-1) at 55 degrees C. The reduced sorption capacity at high temperature was related to the partial enhancement of desorption from granite surface. In general, Cs adsorption was exothermic (DeltaH<0, with median of -12 kJ mol(-1)) and spontaneous (DeltaG<0, with median of -6.1 at 25 degrees C and -5.0 kJ mol(-1) at 55 degrees C). The presence of competing cations such as sodium and potassium ions in synthetic groundwater significantly reduces the Cs adsorption onto granite. The scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM/EDS) mapping method provided substantial evidences that micaceous minerals (biotite in this case) dominate Cs adsorption. These adsorbed Cs ions were notably distributed onto the frayed edges of biotite minerals. More importantly, the locations of these adsorbed Cs were coincided with the potassium depletion area, implying the displacement of K by Cs adsorption. Further XRD patterns displayed a decreased intensity of signal of biotite as the Cs loading increased, revealing that the interlayer space of biotite was affected by Cs adsorption.

  13. Importance of the accuracy of experimental data in the nonlinear chromatographic determination of adsorption energy distributions

    SciTech Connect

    Stanley, B.J.; Guiochon, G. Oak Ridge National Lab., TN )

    1994-11-01

    Adsorption energy distributions (AEDs) are calculated from the classical, fundamental integral equation of adsorption using adsorption isotherms and the expectation-maximization method of parameter estimation. The adsorption isotherms are calculated from nonlinear elution profiles obtained from gas chromatographic data using the characteristic points method of finite concentration chromatography. Porous layer open tubular capillary columns are used to support the adsorbent. The performance of these columns is compared to that of packed columns in terms of their ability to supply accurate isotherm data and AEDs. The effect of the finite column efficiency and the limited loading factor on the accuracy of the estimated energy distributions is presented. This accuracy decreases with decreasing efficiency, and approximately 5000 theoretical plates are needed when the loading factor, L[sub f], equals 0.56 for sampling of a unimodal Gaussian distribution. Increasing L[sub f] further increases the contribution of finite efficiency to the AED and causes a divergence at the low-energy endpoint if too high. This occurs as the retention time approaches the holdup time. Data are presented for diethyl ether adsorption on porous silica and its C-18-bonded derivative. 36 refs., 8 figs., 2 tabs.

  14. Microbiome Remodeling via the Montmorillonite Adsorption-Excretion Axis Prevents Obesity-related Metabolic Disorders.

    PubMed

    Xu, Pengfei; Hong, Fan; Wang, Jialin; Cong, Yusheng; Dai, Shu; Wang, Sheng; Wang, Jing; Jin, Xi; Wang, Fang; Liu, Jin; Zhai, Yonggong

    2017-02-01

    Obesity and its related metabolic disorders are closely correlated with gut dysbiosis. Montmorillonite is a common medicine used to treat diarrhea. We have previously found that dietary lipid adsorbent-montmorillonite (DLA-M) has an unexpected role in preventing obesity. The aim of this study was to further investigate whether DLA-M regulates intestinal absorption and gut microbiota to prevent obesity-related metabolic disorders. Here, we show that DLA-M absorbs free fatty acids (FFA) and endotoxins in vitro and in vivo. Moreover, the combination of fluorescent tracer technique and polarized light microscopy showed that DLA-M crystals immobilized BODIPY® FL C16 and FITC-LPS, respectively, in the digestive tract in situ. HFD-fed mice treated with DLA-M showed mild changes in the composition of the gut microbiota, particularly increases in short-chain fatty acids (SCFA)-producing Blautia bacteria and decreases in endotoxin-producing Desulfovibrio bacteria, these changes were positively correlated with obesity and inflammation. Our results indicated that DLA-M immobilizes FFA and endotoxins in the digestive tract via the adsorption-excretion axis and DLA-M may potentially be used as a prebiotic to prevent intestinal dysbiosis and obesity-associated metabolic disorders in obese individuals.

  15. 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.

  16. 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.

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

    PubMed

    Tiemeyer, Sebastian; Paulus, Michael; Tolan, Metin

    2010-09-07

    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.

  18. Distribution of carbon nanotube sizes from adsorption measurements and computer simulation.

    PubMed

    Kowalczyk, Piotr; Hołyst, Robert; Tanaka, Hideki; Kaneko, Katsumi

    2005-08-04

    The method for the evaluation of the distribution of carbon nanotube sizes from the static adsorption measurements and computer simulation of nitrogen at 77 K is developed. We obtain the condensation/evaporation pressure as a function of pore size of a cylindrical carbon tube using Gauge Cell Monte Carlo Simulation (Gauge Cell MC). To obtain the analytical form of the relationships mentioned above we use Derjaguin-Broekhoff-deBoer theory. Finally, the pore size distribution (PSD) of the single-walled carbon nanohorns (SWNHs) is determined from a single nitrogen adsorption isotherm measured at 77 K. We neglect the conical part of an isolated SWNH tube and assume a structureless wall of a carbon nanotube. We find that the distribution of SWNH sizes is broad (internal pore radii varied in the range 1.0-3.6 nm with the maximum at 1.3 nm). Our method can be used for the determination of the pore size distribution of the other tubular carbon materials, like, for example, multiwalled or double-walled carbon nanotubes. Besides the applicable aspect of the current work the deep insight into the problem of capillary condensation/evaporation in confined carbon cylindrical geometry is presented. As a result, the critical pore radius in structureless single-walled carbon tubes is determined as being equal to three nitrogen collision diameters. Below that size the adsorption-desorption isotherm is reversible (i.e., supercritical in nature). We show that the classical static adsorption measurements combined with the proper modeling of the capillary condensation/evaporation phenomena is a powerful method that can be applied for the determination of the distribution of nanotube sizes.

  19. 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.

  20. Martian Liquid CO2 and Metabolic Heat Regenerated Temperature Swing Adsorption for Portable Life Support Systems

    NASA Astrophysics Data System (ADS)

    Iacomini, Christine; MacCallum, Taber; Morin, Tom; Straub-Lopez, Kathrine; 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. This paper presents a conceptual system for CO2 collection, compression, and cooling to produce sub-critical (liquid) CO2. A first order estimate of the system mass and energy to condense and store liquid CO2 outside at Mars ambient temperature at 600 kPa is discussed. No serious technical hurdles were identified and it is likely that better overall performance would be achieved if the system were part of an integrated ISRU strategy rather than a standalone system. Patent-pending Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology for CO2 removal from a PLSS vent loop, where the Martian liquid CO2 is used as the heat sink is developed to utilize the readily available liquid CO2. This paper will describe the technology and present data in support of its design.

  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. Dynamic adsorption of diarrhetic shellfish poisoning (DSP) toxins in passive sampling relates to pore size distribution of aromatic adsorbent.

    PubMed

    Li, Aifeng; Ma, Feifei; Song, Xiuli; Yu, Rencheng

    2011-03-18

    Solid-phase adsorption toxin tracking (SPATT) technology was developed as an effective passive sampling method for dissolved diarrhetic shellfish poisoning (DSP) toxins in seawater. HP20 and SP700 resins have been reported as preferred adsorption substrates for lipophilic algal toxins and are recommended for use in SPATT testing. However, information on the mechanism of passive adsorption by these polymeric resins is still limited. Described herein is a study on the adsorption of OA and DTX1 toxins extracted from Prorocentrum lima algae by HP20 and SP700 resins. The pore size distribution of the adsorbents was characterized by a nitrogen adsorption method to determine the relationship between adsorption and resin porosity. The Freundlich equation constant showed that the difference in adsorption capacity for OA and DTX1 toxins was not determined by specific surface area, but by the pore size distribution in particular, with micropores playing an especially important role. Additionally, it was found that differences in affinity between OA and DTX1 for aromatic resins were as a result of polarity discrepancies due to DTX1 having an additional methyl moiety.

  5. 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.

  6. 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}.

  7. 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.

  8. Splanchnic insulin metabolism in obesity. Influence of body fat distribution.

    PubMed Central

    Peiris, A N; Mueller, R A; Smith, G A; Struve, M F; Kissebah, A H

    1986-01-01

    The effects of obesity and body fat distribution on splanchnic insulin metabolism and the relationship to peripheral insulin sensitivity were assessed in 6 nonobese and 16 obese premenopausal women. When compared with the nonobese women, obese women had significantly greater prehepatic production and portal vein levels of insulin both basally and following glucose stimulation. This increase correlated with the degree of adiposity but not with waist-to-hip girth ratio (WHR). WHR, however, correlated inversely with the hepatic extraction fraction and directly with the posthepatic delivery of insulin. The latter correlated with the degree of peripheral insulinemia. The decline in hepatic insulin extraction with increasing WHR also correlated with the accompanying diminution in peripheral insulin sensitivity. Increasing adiposity is thus associated with insulin hypersecretion. The pronounced hyperinsulinemia of upper body fat localization, however, is due to an additional defect in hepatic insulin extraction. This defect is closely allied with the decline in peripheral insulin sensitivity. PMID:3537010

  9. Distribution of Hydrogen-Metabolizing Bacteria in Alfalfa Field Soil

    PubMed Central

    Cunningham, Scott D.; Kapulnik, Yoram; Phillips, Donald A.

    1986-01-01

    H2 evolved by alfalfa root nodules during the process of N2 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 H2. Isolates showing net H2 uptake and 3H2 incorporation activity under laboratory conditions were assigned a Hup+ phenotype, whereas organisms with significant H2 output capacity were designated as a Hout+ phenotype. Under aerobic isolation conditions two Hup+ isolates were obtained, whereas under microaerophilic conditions five Hup+ and two Hout+ 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 H2, and 1.2% could produce H2. Two of the Hup+ isolates were identified as Rhizobium meliloti by root nodulation tests, but the fact that none of the isolates reduced C2H2 under the assay conditions suggested that the H2 metabolism traits were associated with various hydrogenase systems rather than with nitrogenase activity. Results from this study support the concept that H2 evolution by alfalfa root nodules has a significant effect on the surrounding microenvironment and influences the number and diversity of bacteria occupying that region. PMID:16347207

  10. Pharmacokinetics, pharmacodynamics, metabolism, distribution, and excretion of carfilzomib in rats.

    PubMed

    Yang, Jinfu; Wang, Zhengping; Fang, Ying; Jiang, Jing; Zhao, Frances; Wong, Hansen; Bennett, Mark K; Molineaux, Christopher J; Kirk, Christopher J

    2011-10-01

    Carfilzomib [(2S)-N-[(S)-1-[(S)-4-methyl-1-[(R)-2-methyloxiran-2-yl]-1-oxopentan-2-ylcarbamoyl]-2-phenylethyl]-2-[(S)-2-(2-morpholinoacetamido)-4-phenylbutanamido]-4-methylpentanamide, also known as PR-171] is a selective, irreversible proteasome inhibitor that has shown encouraging results in clinical trials in multiple myeloma. In this study, the pharmacokinetics, pharmacodynamics, metabolism, distribution, and excretion of carfilzomib in Sprague-Dawley rats were characterized. After intravenous administration, the plasma concentration of carfilzomib declined rapidly in a biphasic manner. Carfilzomib displayed high plasma clearance [195-319 ml/(min · kg)], a short-terminal half-life (5-20 min), and rapid and wide tissue distribution in rats. The exposure to carfilzomib (C(max) and area under the curve) increased dose proportionally from 2 to 4 mg/kg but less than dose proportionally from 4 to 8 mg/kg. The high clearance was mediated predominantly by extrahepatic metabolism through peptidase cleavage and epoxide hydrolysis. Carfilzomib was excreted mainly as metabolites resulting from peptidase cleavage. Carfilzomib and its major metabolites in urine and bile accounted for approximately 26 and 31% of the total dose, respectively, for a total of 57% within 24 h postdose. Despite the high systemic clearance, potent proteasome inhibition was observed in blood and a variety of tissues. Together with rapid and irreversible target binding, the high clearance may provide an advantage in that "unnecessary" exposure to the drug is minimized and potential drug-related side effects may be reduced.

  11. 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.

  12. 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.

  13. Distribution and factors affecting adsorption of sterols in the surface sediments of Bosten Lake and Manas Lake, Xinjiang.

    PubMed

    Liu, Jiang; Yao, Xiaorui; Lu, Jianjiang; Qiao, Xiuwen; Liu, Zilong; Li, Shanman

    2016-03-01

    This study investigated the concentrations and distribution of eight sterol compounds in the surface sediments of Bosten Lake and Manas Lake, Xinjiang, China. The ratios of sterols as diagnostic indices were used to identify pollution sources. The sediment of the two lakes was selected as an adsorbent to investigate the adsorption behaviour of sterols. Results showed that the sterols were widely distributed in the sediments of the lakes in the study areas. The total concentrations of the detected sterols in Bosten Lake and in Manas Lake were 1.584-27.897 and 2.048-18.373 μg g(-1)∙dw, respectively. In all of the sampling sites, the amount of faecal sterols was less than that of plant sterols. β-sitosterol was the dominant plant sterol with a mean concentration of 2.378 ± 2.234 μg g(-1)∙dw; cholesterol was the most abundant faecal sterol with a mean concentration of 1.060 ± 1.402 μg g(-1)∙dw. The pollution level was higher in Bosten Lake than in Manas Lake. Majority of the ratios clearly demonstrated that the contamination by human faecal sources was occurring at stations which are adjacent to residential areas and water inlets. The adsorption behaviour of sterols to sediment suggested that the sterol adsorption coefficients were reduced as temperature increased. As salinity increased, the adsorption quantity also increased. As pH increased, the sediment adsorption of sterol slightly increased because the strong alkaline solution is not conducive to the adsorption of sterols. The ratios between sterols did not change largely with the change in external factors.

  14. 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.

  15. 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

  16. 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

  17. 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

    2015-02-03

    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.

  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.; 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.

  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.; 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.

  20. Competitive adsorption of As(III), As(V), Sb(III) and Sb(V) onto ferrihydrite in multi-component systems: Implications for mobility and distribution.

    PubMed

    Qi, Pengfei; Pichler, Thomas

    2017-05-15

    The simultaneous adsorption behavior and competitive interactions between As(III), As(V), Sb(III) and Sb(V) by ferrihydrite were evaluated in multi-component (binary, ternary, quaternary) systems. In binary systems, Sb(III) had a stronger inhibitory influence on As(III) adsorption than Sb(V) did, and As(V) had a stronger inhibitory effect on Sb(V) adsorption than As(III) did. In ternary systems, NO3(-), PO4(3-) and SO4(2-) did not compete with the adsorption of As(III) and Sb(III). NO3(-) and SO4(2-) also had no distinct effect on the adsorption of As(V) and Sb(V), while PO4(3-) competed with As(V) and Sb(V) for surface sites. In quaternary systems, the simultaneous adsorption behavior of the four redox species was pH dependent. Sb(III) always showed the strongest adsorption affinity regardless of pH. At pH 3.5 As(III) showed the lowest affinity could be due to the presence and negative effect of Sb(III) and As(V). The Freundlich model provided a good fit for the simultaneous adsorption data under quaternary conditions. The study of competitive/simultaneous adsorption of the four possible redox species onto ferrihydrite contributed to a better understanding of their distribution, mobility and fate in the environment.

  1. 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.

  2. Factors governing adsorption and distribution of copper in Samut Prakarn coastal sediment, Thailand.

    PubMed

    Ratasuk, Phanit; Parkpian, Preeda; Jugsujinda, Aroon; DeLaune, R D

    2003-09-01

    The Chao Phraya River (near Bangkok) discharges into Gulf of Thailand. Sediment in near shore areas of the gulf contained elevated Cu levels as a result of industry and urban inputs into the region. Adsorption and fractionation studies were conducted for determining availability and retention of Cu in the sediment. Adsorption studies showed that the coastal sediment has a very high capacity to adsorb Cu (in a range of 1500-4000 microg g(-1)). The high organic matter content and clay content of the sediment contributed significantly to the binding of Cu. Increased salinity levels up to 50 ppt had no effect on the adsorption of Cu by the sediment. The results from Cu partitioning and adsorption study further indicate that Cu in sediment in this coastal region is not likely to be easily released into the water phase where the Cu could be toxic to aquatic organisms. Result shows over the short term current inputs of Cu in Samut Prakarn Coastal region will be rapidly adsorbed by the sediment with little return into water column.

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

    DTIC Science & Technology

    2014-11-14

    expression data. The proposed algorithm minimizes a weighted sum of flux magnitudes, while biomass production can be bounded to fit an ample range from...approach to investigate metabolism and metabolic processes is to analyze the flow of material and energy through a metabolic network. In particular, the...maximizing a certain fitness function (typically, biomass production) and estimates the flux distribution by solving a linear programming (LP

  4. 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.

  5. Distribution and metabolism of galactitol in Euonymus japonica L

    SciTech Connect

    Boersig, M.R.; Negm, F.B.

    1987-04-01

    Metabolism of (/sup 14/C)-galactitol was studied in immature and mature leaves of Euonymus japonica L. The highest rates of galactitol metabolism occurred in young expanding leaves. After a 12 h incubation in (/sup 14/C)-galactitol, the proportions of label remaining in galactitol were 82 and 96% in immature and mature tissues, respectively. A NAD dependent galactitol dehydrogenase reaction was demonstrated in extracts from immature leaves. The product of this reaction was the aldose sugar, galactose. Label from (/sup 14/C)-galactitol was detected in two unidentified carbohydrates as well as in sucrose, glucose, fructose and galactose. When incubated with (/sup 14/C)-galactose, immature and mature leaf strips, respectively, accumulated 1 and 22% of the label in the form of galactitol.

  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.

  9. The relationship of metabolic performance and distribution in black-capped and Carolina chickadees.

    PubMed

    Olson, Jennifer R; Cooper, Sheldon J; Swanson, David L; Braun, Michael J; Williams, Joseph B

    2010-01-01

    In endotherms, metabolic performance is associated with a wide array of ecological traits, including species distribution. Researchers have suggested that the northern boundaries of North American passerines are limited by their ability to sustain the high metabolic rates required for thermoregulation. Black-capped chickadees (Poecile atricapillus; BC) are year-round residents in most of Canada and the northern half of the United States, whereas Carolina chickadees (Poecile carolinensis; CA) are found exclusively in the southeastern United States. These species hybridize along a narrow contact zone that has been moving northward at a rate of about 1.6 km per decade, coincident with warming temperatures in Ohio. The location of the chickadee hybrid zone in Ohio closely matches air temperature isotherms, further suggesting that metabolic rate may correlate with distribution in these species. We tested the hypothesis that distribution patterns of chickadees are linked with their rate of metabolism. For populations of BC and CA chickadees, we measured basal metabolic rates (BMRs) and cold-induced peak metabolic rates from areas that differ in winter temperatures and supplemented this information with data from other studies. Although our findings suggest a general relationship between lower air temperatures and higher metabolic rate among black-capped chickadee populations, this trend was not robust across all locations. There was no significant relationship between lower air temperatures and metabolism in Carolina chickadees. Within Ohio, hybrids had a significantly higher mass-corrected BMR than either parental species. We suggest that the mtDNA-nDNA mismatch of hybrids may produce less efficient mitochondrial protein complexes, which in turn affects the efficiency of ATP production, thereby increasing rate of oxygen consumption to meet ATP demands.

  10. A metabolite-centric view on flux distributions in genome-scale metabolic models

    PubMed Central

    2013-01-01

    Background Genome-scale metabolic models are important tools in systems biology. They permit the in-silico prediction of cellular phenotypes via mathematical optimisation procedures, most importantly flux balance analysis. Current studies on metabolic models mostly consider reaction fluxes in isolation. Based on a recently proposed metabolite-centric approach, we here describe a set of methods that enable the analysis and interpretation of flux distributions in an integrated metabolite-centric view. We demonstrate how this framework can be used for the refinement of genome-scale metabolic models. Results We applied the metabolite-centric view developed here to the most recent metabolic reconstruction of Escherichia coli. By compiling the balance sheets of a small number of currency metabolites, we were able to fully characterise the energy metabolism as predicted by the model and to identify a possibility for model refinement in NADPH metabolism. Selected branch points were examined in detail in order to demonstrate how a metabolite-centric view allows identifying functional roles of metabolites. Fructose 6-phosphate aldolase and the sedoheptulose bisphosphate bypass were identified as enzymatic reactions that can carry high fluxes in the model but are unlikely to exhibit significant activity in vivo. Performing a metabolite essentiality analysis, unconstrained import and export of iron ions could be identified as potentially problematic for the quality of model predictions. Conclusions The system-wide analysis of split ratios and branch points allows a much deeper insight into the metabolic network than reaction-centric analyses. Extending an earlier metabolite-centric approach, the methods introduced here establish an integrated metabolite-centric framework for the interpretation of flux distributions in genome-scale metabolic networks that can complement the classical reaction-centric framework. Analysing fluxes and their metabolic context simultaneously opens

  11. 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.

  12. 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.

  13. 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...

  14. Simulation of porosity decrease with protein adsorption using the distributed pore model.

    PubMed

    Coquebert de Neuville, Bertrand; Thomas, Helen; Morbidelli, Massimo

    2013-11-01

    Chromatographic stationary phases such as Fractogel EMD SO3 (M) have a pore size distribution that is close to the size of proteins. The accessible porosity and the mass transfer inside the particles are therefore strongly affected by the pore to solute size ratio. This effect was simulated using the distributed pore model for three media: Base Fractogel SO3, Fractogel EMD SO3 (M) and (S). This model was extended so as to be able to account for the effect of pore shrinkage due to protein loading on the chromatographic behavior of other proteins. Pulse chromatographic experiments using dextrans of various sizes on column pre-loaded with antibodies have been conducted to test the model reliability.

  15. Software LS-MIDA for efficient mass isotopomer distribution analysis in metabolic modelling

    PubMed Central

    2013-01-01

    Background The knowledge of metabolic pathways and fluxes is important to understand the adaptation of organisms to their biotic and abiotic environment. The specific distribution of stable isotope labelled precursors into metabolic products can be taken as fingerprints of the metabolic events and dynamics through the metabolic networks. An open-source software is required that easily and rapidly calculates from mass spectra of labelled metabolites, derivatives and their fragments global isotope excess and isotopomer distribution. Results The open-source software “Least Square Mass Isotopomer Analyzer” (LS-MIDA) is presented that processes experimental mass spectrometry (MS) data on the basis of metabolite information such as the number of atoms in the compound, mass to charge ratio (m/e or m/z) values of the compounds and fragments under study, and the experimental relative MS intensities reflecting the enrichments of isotopomers in 13C- or 15 N-labelled compounds, in comparison to the natural abundances in the unlabelled molecules. The software uses Brauman’s least square method of linear regression. As a result, global isotope enrichments of the metabolite or fragment under study and the molar abundances of each isotopomer are obtained and displayed. Conclusions The new software provides an open-source platform that easily and rapidly converts experimental MS patterns of labelled metabolites into isotopomer enrichments that are the basis for subsequent observation-driven analysis of pathways and fluxes, as well as for model-driven metabolic flux calculations. PMID:23837681

  16. Critical evaluation and comparison of fluid distribution systems for industrial scale expanded bed adsorption chromatography columns.

    PubMed

    Arpanaei, A; Heebøll-Nielsen, A; Hubbuch, J J; Thomas, O R T; Hobley, T J

    2008-07-11

    The hydrodynamic properties of an expanded bed contactor with 30 cm or 150 cm internal diameter, which employs a rotating or oscillating fluid distributor, were compared to prototype columns of 60 cm or 150 cm diameter employing local stirring (fixed wall nozzles plus central bottom mounted stirrer) for fluid distribution. Fluid introduction through a rotating fluid distributor was found to give superior hydrodynamic characteristics in the 30 cm and 150 cm diameter column compared to using the local stirrer in both the 60 cm and 150 cm diameter columns. The shortcomings of the local stirring distributor at large scale were apparent: dead zones were present which could not be removed by increasing rotation rates or flow rates, and such changes led to a deterioration in hydrodynamic properties. In contrast, during fluid introduction through a rotating distributor no dead zones were observed, and residence time distribution tests showed that plate numbers remained constant or increased slightly as flow rate was raised from 200 cm h(-1) to 470 cm h(-1). Under the conditions studied, oscillation of the rotating fluid distributor led to increased mixing and poorer performance than rotary movement. The results imply that further improvement in distributor design is needed and careful attention should be given to the trade off between turbulence and adequate fluid distribution.

  17. Prediction of metabolic flux distribution from gene expression data based on the flux minimization principle.

    PubMed

    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.

  18. 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.

  19. 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.

  20. 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‰).

  1. 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 ... Physiology . 14th ed. Hoboken, NJ: John Wiley & Sons; 2014:chap ...

  2. Metabolism

    MedlinePlus

    ... El metabolismo Metabolism Basics Our bodies get the energy they need from food through metabolism, the chemical ... that convert the fuel from food into the energy needed to do everything from moving to thinking ...

  3. 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

  4. 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

  5. MID Max: LC-MS/MS Method for Measuring the Precursor and Product Mass Isotopomer Distributions of Metabolic Intermediates and Cofactors for Metabolic Flux Analysis Applications.

    PubMed

    McCloskey, Douglas; Young, Jamey D; Xu, Sibei; Palsson, Bernhard O; Feist, Adam M

    2016-01-19

    The analytical challenges to acquire accurate isotopic data of intracellular metabolic intermediates for stationary, nonstationary, and dynamic metabolic flux analysis (MFA) are numerous. This work presents MID Max, a novel LC-MS/MS workflow, acquisition, and isotopomer deconvolution method for MFA that takes advantage of additional scan types that maximizes the number of mass isotopomer distributions (MIDs) that can be acquired in a given experiment. The analytical method was found to measure the MIDs of 97 metabolites, corresponding to 74 unique metabolite-fragment pairs (32 precursor spectra and 42 product spectra) with accuracy and precision. The compounds measured included metabolic intermediates in central carbohydrate metabolism and cofactors of peripheral metabolism (e.g., ATP). Using only a subset of the acquired MIDs, the method was found to improve the precision of flux estimations and number of resolved exchange fluxes for wild-type E. coli compared to traditional methods and previously published data sets.

  6. 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...

  7. In vivo metabolism of organophosphate flame retardants and distribution of their main metabolites in adult zebrafish.

    PubMed

    Wang, Guowei; Chen, Hanyan; Du, Zhongkun; Li, Jianhua; Wang, Zunyao; Gao, Shixiang

    2017-07-15

    Understanding the metabolism of chemicals as well as the distribution and depuration of their main metabolites in tissues are essential for evaluating their fate and potential toxicity in vivo. Herein, we investigated the metabolism of six typical organophosphate (OP) flame retardants (tripropyl phosphate (TPRP), tri-n-butyl phosphate (TNBP), tris(2-butoxyethyl) phosphate (TBOEP), tris(2-chloroethyl) phosphate (TCEP), tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) and tri-p-cresyl phosphate (p-TCP)) in adult zebrafish in laboratory at three levels (0, 1/150 LC50 (environmentally relevant level), and 1/30 LC50 per OP analog). Twenty main metabolites were detected in the liver of OPs-exposed zebrafish using high resolution mass spectrometry (Q-TOF). The reaction pathways involving scission of the ester bond (hydrolysis), cleavage of the ether bond, oxidative hydroxylation, dechlorination, and coupling with glucuronic acid were proposed, and were further confirmed by the frontier electron density and point charge calculations. Tissue distribution of the twenty metabolites revealed that liver and intestine with the highest levels of metabolites were the most active organs for OPs biotransformation among the studied tissues of intestine, liver, roe, brain, muscle, and gill, which showed the importance of hepatobiliary system (liver-bile-intestine) in the metabolism and excretion of OPs in zebrafish. Fast depuration of metabolites from tissues indicated that the formed metabolites might be not persistent in fish, and easily released into water. This study provides comprehensive information on the metabolism of OPs in the tissue of zebrafish, which might give some hints for the exploration of their toxic mechanism in aquatic life.

  8. 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

  9. Comparative aspects of the distribution, metabolism, and excretion of six iodothyronines in the rat

    SciTech Connect

    DiStefano, J.J. III; Feng, D.

    1988-11-01

    We have studied the kinetics of 3 iodothyronines, 3,3'-diiodothyronine (T2), 3',5'-T2, and 3'-monoiodothyronine (T1), in groups of young adult male rats maintained under normal steady state physiological conditions. We have also performed a comparative analysis of these results, combined with corresponding kinetic indices of T4, T3, and rT3, to obtain a more comprehensive understanding of normal thyroid hormone production, distribution, and metabolism. Tracer doses of 125I-labeled 3,3'-T2, 3',5'-T2, and 3'-T1 were separately injected iv, and blood samples were collected 6-12 times for each iodothyronine in optimized sequential kinetic studies designed to maximize the precision of kinetic parameters. Labeled iodothyronines were separated quantitatively from their metabolites in each plasma sample by Sephadex G-25 column chromatography. Conventional kinetic analysis of the resulting data generated distribution volume, clearance, turnover, and mean residence time indices for each iodothyronine, and concomitant compartmental analysis of the same data provided additional results useful for integration and comparative analysis of the 6 iodothyronines. Kinetic parameters for all but T4 and T3 were similar, suggesting that similar mechanisms are responsible for the transport, metabolism, and distribution of nonhormonal iodothyronines. All but T4 and T3 (and, to a much lesser extent, 3'-T1) were almost completely and irreversibly metabolized, whereas 24-30% of the hormones (and 6% of 3'-T1) were excreted as such in feces only. Three-pool models fitted individual plasma kinetic data sets best in all cases (for all 6 iodothyronines), each with a plasma, a slowly exchanging (slow), and a rapidly exchanging (fast) pool, and kinetic parameters of interest were quantified for each iodothyronine (Ti).

  10. 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

  11. Metabolism

    MedlinePlus

    ... and intestines. Several of the hormones of the endocrine system are involved in controlling the rate and direction ... For Kids For Parents MORE ON THIS TOPIC Endocrine System What Can I Do About My High Metabolism? ...

  12. Metabolism

    MedlinePlus

    ... symptoms. Metabolic diseases and conditions include: Hyperthyroidism (pronounced: hi-per-THIGH-roy-dih-zum). Hyperthyroidism is caused ... or through surgery or radiation treatments. Hypothyroidism (pronounced: hi-po-THIGH-roy-dih-zum). Hypothyroidism is caused ...

  13. 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.

  14. Absorption, Distribution, Metabolism and Excretion of 3-MCPD 1-Monopalmitate after Oral Administration in Rats.

    PubMed

    Gao, Boyan; Liu, Man; Huang, Guoren; Zhang, Zhongfei; Zhao, Yue; Wang, Thomas T Y; Zhang, Yaqiong; Liu, Jie; Yu, Liangli

    2017-03-15

    Fatty acid esters of monochloropropane 1,2-diol (3-MCPD) are processing-induced toxicants and have been detected in several food categories. This study investigated the absorption, distribution, metabolism, and excretion of 3-MCPD esters in Sprague-Dawley (SD) rats using 3-MCPD 1-monopalmitate as the probe compound. The kinetics of 3-MCPD 1-monopalmitate in plasma was investigated using SD rats, and the results indicated that 3-MCPD 1-monopalmitate was absorbed directly in vivo and metabolized. Its primary metabolites in the liver, kidney, testis, brain, plasma, and urine were tentatively identified and measured at 6, 12, 24, and 48 h after oral administration. Structures were proposed for eight metabolites. 3-MCPD 1-monopalmitate was converted to free 3-MCPD, which formed the phase II metabolites. All of the metabolites were chlorine-related chemical components; most of them existed in urine, reflecting the excretion pattern of 3-MCPD esters. Understanding the metabolism of 3-MCPD esters in vivo is critical for assessing their toxicities.

  15. Distribution of zooplankton biomass and potential metabolic activities across the northern Benguela upwelling system

    NASA Astrophysics Data System (ADS)

    Fernández-Urruzola, I.; Osma, N.; Packard, T. T.; Gómez, M.; Postel, L.

    2014-11-01

    The distribution of zooplankton biomass and potential metabolic rates, in terms of electron transport system (ETS) and glutamate dehydrogenase (GDH), were analyzed along a cross-shelf transect in waters off Namibia. The highly variable dynamics of upwelling filaments promoted short-term fluctuations in the zooplankton biomass and metabolism. Maximum values were characteristically found over the shelf-break, where zooplankton biomass as dry mass (DM) reached peaks of 64.5 mg m- 3 within the upper 200 m in late August. Two weeks later, the zooplankton-DM decreased by more than a third (19 mg DM m- 3). Zooplankton potential respiration and NH4+ excretion averaged 234 μmol O2 m- 3 d- 1 and 169 μmol NH4+ m- 3 d- 1 in the Namibian shelf, respectively. High protein-specific ETS activities even in the low-chlorophyll waters outside the filament suggested a shift into greater omnivory seaward. In this light, zooplankton elemental and isotopic compositions were used to investigate the pelagic food web interactions. They evidenced spatial changes in the carbon resource for zooplankton as well as changes in the form of nitrogen that fueled the biological production in aging advected waters. Overall, both aspects of zooplankton metabolism impacted the primary productivity at a level less than 10% under all the different oceanographic conditions.

  16. 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.

  17. 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.

  18. Effects of hyperglycemia and effects of ketosis on cerebral perfusion, cerebral water distribution, and cerebral metabolism.

    PubMed

    Glaser, Nicole; Ngo, Catherine; Anderson, Steven; Yuen, Natalie; Trifu, Alexandra; O'Donnell, Martha

    2012-07-01

    Diabetic ketoacidosis (DKA) may cause brain injuries in children. The mechanisms responsible are difficult to elucidate because DKA involves multiple metabolic derangements. We aimed to determine the independent effects of hyperglycemia and ketosis on cerebral metabolism, blood flow, and water distribution. We used magnetic resonance spectroscopy to measure ratios of cerebral metabolites (ATP to inorganic phosphate [Pi], phosphocreatine [PCr] to Pi, N-acetyl aspartate [NAA] to creatine [Cr], and lactate to Cr) and diffusion-weighted imaging and perfusion-weighted imaging to assess cerebral water distribution (apparent diffusion coefficient [ADC] values) and cerebral blood flow (CBF) in three groups of juvenile rats (hyperglycemic, ketotic, and normal control). ATP-to-Pi ratio was reduced in both hyperglycemic and ketotic rats in comparison with controls. PCr-to-Pi ratio was reduced in the ketotic group, and there was a trend toward reduction in the hyperglycemic group. No significant differences were observed in NAA-to-Cr or lactate-to-Cr ratio. Cortical ADC was reduced in both groups (indicating brain cell swelling). Cortical CBF was also reduced in both groups. We conclude that both hyperglycemia and ketosis independently cause reductions in cerebral high-energy phosphates, CBF, and cortical ADC values. These effects may play a role in the pathophysiology of DKA-related brain injury.

  19. Fat distribution and adipose tissue metabolism in non-obese male black African and Caucasian subjects.

    PubMed

    Ama, P F; Poehlman, E T; Simoneau, J A; Boulay, M R; Thériault, G; Tremblay, A; Bouchard, C

    1986-01-01

    Twenty-four male black African (25.5 +/- 3.0, mean +/- s.d., years of age) and 24 male Caucasian (21.5 +/- 3.6) subjects, ascertained as sedentary individuals, participated in this study designed to determine whether there were racial differences in fat distribution and adipose tissue metabolism while controlling the differences in body fat. An adipose tissue biopsy was obtained from the suprailiac region for the determination of basal (BL), epinephrine submaximal 10(-4) M (ESML) and maximal 10(-3) M (EML) stimulated lipolysis, basal (BLG) and maximal insulin 9 microU/ml (ILG) stimulated lipogenesis and heparin releasable lipoprotein lipase (LPL) activity. Body density was determined through underwater weighing procedures and body fat derived with the Siri equation. The following skinfolds were also measured: triceps, biceps, subscapular, abdomen, suprailiac, front thigh and medial calf. Caucasians were matched with the black Africans for age, body weight and body density. Results indicated that when Caucasians and black Africans of similar percentage body fat were compared, no significant differences were observed in the total amount of subcutaneous fat, fat distribution and suprailiac mean fat cell size. Moreover, no significant differences were observed between the two groups for BL, BLG, and ILG of adipose tissue. However, black Africans had higher (P less than 0.01) epinephrine stimulated lipolytic values (ESML and EML) and LPL activity (P less than 0.01) than the Caucasian subjects. These results suggest that for a comparable level of fatness and similar fat morphology and distribution, there are racial differences in adipose tissue metabolism.

  20. Metabolic flux distribution analysis by 13C-tracer experiments using the Markov chain-Monte Carlo method.

    PubMed

    Yang, J; Wongsa, S; Kadirkamanathan, V; Billings, S A; Wright, P C

    2005-12-01

    Metabolic flux analysis using 13C-tracer experiments is an important tool in metabolic engineering since intracellular fluxes are non-measurable quantities in vivo. Current metabolic flux analysis approaches are fully based on stoichiometric constraints and carbon atom balances, where the over-determined system is iteratively solved by a parameter estimation approach. However, the unavoidable measurement noises involved in the fractional enrichment data obtained by 13C-enrichment experiment and the possible existence of unknown pathways prevent a simple parameter estimation method for intracellular flux quantification. The MCMC (Markov chain-Monte Carlo) method, which obtains intracellular flux distributions through delicately constructed Markov chains, is shown to be an effective approach for deep understanding of the intracellular metabolic network. Its application is illustrated through the simulation of an example metabolic network.

  1. Association of erythrocyte deformability with red blood cell distribution width in metabolic diseases and thalassemia trait.

    PubMed

    Vayá, Amparo; Alis, Rafael; Suescún, Marta; Rivera, Leonor; Murado, Julian; Romagnoli, Marco; Solá, Eva; Hernandez-Mijares, Antonio

    2015-01-01

    Increased red blood distribution width (RDW) in anemia is related to disturbances in the cellular surface/volume ratio, usually accompanied by morphological alterations, while it has been shown in inflammatory diseases that the activity of pro-inflammatory cytokines disturbing erythropoiesis increases RDW. Recently it has been reported that higher RDW is related with decreased erythrocyte deformability, and that it could be related with the association of RDW and increased risk of cardiovascular diseases. In order to analyze the influence of morphological alterations and proinflammatory status on the relationship between RDW and erythrocyte deformability, we analyzed erythrocyte deformability along with RDW and other hematological and biochemical parameters in 36 α-thalassemia, 20 β-thalassemia, 20 δβ-thalassemia trait carriers, 61 metabolic syndrome patients and 76 morbidly obese patients. RDW correlated inversely with erythrocyte deformability in minor β-thalassemia (r =-0.530, p <  0.05), and directly in both metabolic syndrome and morbidly obese patients (ρ= 0.270, p <  0.05 and ρ= 0.258, p <  0.05, respectively). Minor β-thalassemia is often accompanied by more marked cell-shaped perturbations than other thalassemia traits. This could be the reason for this negative association only in this setting. Higher anisocytosis seems to be associated with greater morphologic alterations (shape/volume), which reduce erythrocyte deformability. The proinflammatory profile in metabolic patients can be related to the positive association of RDW with erythrocyte deformability found in these patients. However, further research is needed to explain the mechanisms underlying this association.

  2. 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.

  3. 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

  4. MTBE inhaled alone and in combination with gasoline vapor: uptake, distribution, metabolism, and excretion in rats.

    PubMed

    Benson, J M; Barr, E B; Krone, J R

    2001-05-01

    The purpose of these studies was to extend previous evaluation of methyl tert-butyl ether (MTBE)* tissue distribution, metabolism, and excretion in rats to include concentrations more relevant to human exposure (4 and 40 ppm) and to determine the effects of coinhalation of the volatile fraction of unleaded gasoline on the tissue distribution, metabolism, and excretion of MTBE. Groups of male F344 rats were exposed nose-only for 4 hours to 4, 40, or 400 ppm 14C-MTBE or to 20 or 200 ppm of the light fraction of unleaded gasoline (LFG) containing 4 or 40 ppm 14C-MTBE, respectively. To evaluate the effects of repeated inhalation of LFG on MTBE tissue distribution, metabolism, and excretion, rats were exposed for 4 hours on each of 7 consecutive days to 20 or 200 ppm LFG with MTBE (4 or 40 ppm) followed on the eighth day by a similar exposure to LFG containing 14C-MTBE. Subgroups of rats were evaluated for respiratory parameters, initial body burdens, rates and routes of excretion, and tissue distribution and elimination. The concentrations of MTBE and its chief metabolite, tert-butyl alcohol (TBA), were measured in blood and kidney immediately after exposure, and the major urinary metabolites-2-hydroxyisobutyric acid (IBA) and 2-methyl-1,2-propanediol (2MePD)-were measured in urine. Inhalation of MTBE alone or as a component of LFG had no concentration-dependent effect on respiratory minute volume. The initial body burdens of MTBE equivalents achieved after 4 hours of exposure to MTBE did not increase linearly with exposure concentration. MTBE equivalents rapidly distributed to all tissues examined, with the largest percentages distributed to liver. The observed initial body burden did not increase linearly between 4 and 400 ppm. At 400 ppm, elimination half-times of MTBE equivalents from liver increased and from lung, kidney, and testes decreased compared with the two smaller doses. Furthermore, at 400 ppm the elimination half-time for volatile organic compounds (VOCs

  5. SVD identifies transcript length distribution functions from DNA microarray data and reveals evolutionary forces globally affecting GBM metabolism.

    PubMed

    Bertagnolli, Nicolas M; Drake, Justin A; Tennessen, Jason M; Alter, Orly

    2013-01-01

    To search for evolutionary forces that might act upon transcript length, we use the singular value decomposition (SVD) to identify the length distribution functions of sets and subsets of human and yeast transcripts from profiles of mRNA abundance levels across gel electrophoresis migration distances that were previously measured by DNA microarrays. We show that the SVD identifies the transcript length distribution functions as "asymmetric generalized coherent states" from the DNA microarray data and with no a-priori assumptions. Comparing subsets of human and yeast transcripts of the same gene ontology annotations, we find that in both disparate eukaryotes, transcripts involved in protein synthesis or mitochondrial metabolism are significantly shorter than typical, and in particular, significantly shorter than those involved in glucose metabolism. Comparing the subsets of human transcripts that are overexpressed in glioblastoma multiforme (GBM) or normal brain tissue samples from The Cancer Genome Atlas, we find that GBM maintains normal brain overexpression of significantly short transcripts, enriched in transcripts that are involved in protein synthesis or mitochondrial metabolism, but suppresses normal overexpression of significantly longer transcripts, enriched in transcripts that are involved in glucose metabolism and brain activity. These global relations among transcript length, cellular metabolism and tumor development suggest a previously unrecognized physical mode for tumor and normal cells to differentially regulate metabolism in a transcript length-dependent manner. The identified distribution functions support a previous hypothesis from mathematical modeling of evolutionary forces that act upon transcript length in the manner of the restoring force of the harmonic oscillator.

  6. Subcellular Distribution of Enzymes of Glycolate Metabolism in the Alga Cyanidium caldarium1

    PubMed Central

    Gross, Wolfgang; Beevers, Harry

    1989-01-01

    The intracellular distribution of enzymes capable of catalyzing the reactions from phosphoglycolate to glycerate in the bluegreen colored eucaryotic alga Cyanidium caldarium has been studied. After separating the organelles from a crude homogenate on a linear flotation gradient, the enzymes glycolate oxidase and glutamate-glyoxylate aminotransferase along with catalase were present in the peroxisomal fraction (density: 1.23 grams per cubic centimeter). Serine hydroxymethyltransferase was found in the mitochondrial fraction (density: 1.18 grams per cubic centimeter). In contrast to the observations in green leaves of higher plants, the enzymes for the conversion of serine to glycerate (serine-glyoxylate aminotransferase and hydroxypyruvate reductase) were found only in the soluble fraction of the gradient. The partial characterization of enzymes from Cyanidium participating in glycolate metabolism revealed only slight differences from the corresponding enzymes from higher plants. The phylogenetic implications of the observed similarities between the enigmatic alga Cyanidium and higher plants are discussed. PMID:16666880

  7. Thimerosal distribution and metabolism in neonatal mice: comparison with methyl mercury.

    PubMed

    Zareba, Grazyna; Cernichiari, Elsa; Hojo, Rieko; Nitt, Scott Mc; Weiss, Bernard; Mumtaz, Moiz M; Jones, Dennis E; Clarkson, Thomas W

    2007-01-01

    Thimerosal, which releases the ethyl mercury radical as the active species, has been used as a preservative in many currently marketed vaccines throughout the world. Because of concerns that its toxicity could be similar to that of methyl mercury, it is no longer incorporated in many vaccines in the United States. There are reasons to believe, however, that the disposition and toxicity of ethyl mercury compounds, including thimerosal, may differ substantially from those of the methyl form. The current study sought to compare, in neonatal mice, the tissue concentrations, disposition and metabolism of thimerosal with that of methyl mercury. ICR mice were given single intramuscular injections of thimerosal or methyl mercury (1.4 mg Hg kg(-1)) on postnatal day 10 (PND 10). Tissue samples were collected daily on PND 11-14. Most analysed tissues demonstrated different patterns of tissue distribution and a different rate of mercury decomposition. The mean organic mercury in the brain and kidneys was significantly lower in mice treated with thimerosal than in the methyl mercury-treated group. In the brain, thimerosal-exposed mice showed a steady decrease of organic mercury levels following the initial peak, whereas in the methyl mercury-exposed mice, concentrations peaked on day 2 after exposure. In the kidneys, thimerosal-exposed mice retained significantly higher inorganic mercury levels than methyl mercury-treated mice. In the liver both organic and inorganic mercury concentrations were significantly higher in thimerosal-exposed mice than in the methyl mercury group. Ethyl mercury was incorporated into growing hair in a similar manner to methyl mercury. The data showing significant kinetic differences in tissue distribution and metabolism of mercury species challenge the assumption that ethyl mercury is toxicologically identical to methyl mercury.

  8. In ovo uptake, metabolism, and tissue-specific distribution of chiral PCBs and PBDEs in developing chicken embryos

    PubMed Central

    Li, Zong-Rui; Luo, Xiao-Jun; Huang, Li-Qian; Mai, Bi-Xian

    2016-01-01

    Fertilized chicken eggs were injected with environmental doses of 4 chiral polychlorinated biphenyls (PCBs) and 8 polybrominated biphenyl ethers (PBDEs) to investigate their uptake, metabolism in the embryo, and distribution in the neonate chicken. PCB95 uptake was the most efficient (80%) whereas BDE209 was the least (56%). Embryos metabolized approximately 52% of the PCBs absorbed. Though some degree of metabolism in the first 18 days, most of the PCBs and PBDEs was metabolized in the last three days, when BDE85, 99, 153, and 209 decrease by 11–37%. Enantioselective metabolism of the (+) enantiomers of PCB95, 149, and 132 and the (−) enantiomer of PCB91 was observed. The enantioselective reactivity was higher with the two penta-PCBs than the two tetra-PCBs. Liver, exhibited high affinity for high lipophilic chemicals, enrich all chemicals that was deflected in other tissues except for some special chemicals in a given tissues. Lipid composition, time of organ formation, and metabolism contribute to the distribution of chemicals in the neonate chicken. The result of this study will improve our understanding on the fate and potential adverse effects of PCBs and PBDEs in the neonate chicken. PMID:27819361

  9. In ovo uptake, metabolism, and tissue-specific distribution of chiral PCBs and PBDEs in developing chicken embryos

    NASA Astrophysics Data System (ADS)

    Li, Zong-Rui; Luo, Xiao-Jun; Huang, Li-Qian; Mai, Bi-Xian

    2016-11-01

    Fertilized chicken eggs were injected with environmental doses of 4 chiral polychlorinated biphenyls (PCBs) and 8 polybrominated biphenyl ethers (PBDEs) to investigate their uptake, metabolism in the embryo, and distribution in the neonate chicken. PCB95 uptake was the most efficient (80%) whereas BDE209 was the least (56%). Embryos metabolized approximately 52% of the PCBs absorbed. Though some degree of metabolism in the first 18 days, most of the PCBs and PBDEs was metabolized in the last three days, when BDE85, 99, 153, and 209 decrease by 11–37%. Enantioselective metabolism of the (+) enantiomers of PCB95, 149, and 132 and the (‑) enantiomer of PCB91 was observed. The enantioselective reactivity was higher with the two penta-PCBs than the two tetra-PCBs. Liver, exhibited high affinity for high lipophilic chemicals, enrich all chemicals that was deflected in other tissues except for some special chemicals in a given tissues. Lipid composition, time of organ formation, and metabolism contribute to the distribution of chemicals in the neonate chicken. The result of this study will improve our understanding on the fate and potential adverse effects of PCBs and PBDEs in the neonate chicken.

  10. Generalized random sequential adsorption

    NASA Astrophysics Data System (ADS)

    Tarjus, G.; Schaaf, P.; Talbot, J.

    1990-12-01

    Adsorption of hard spherical particles onto a flat uniform surface is analyzed by using generalized random sequential adsorption (RSA) models. These models are defined by releasing the condition of immobility present in the usual RSA rules to allow for desorption or surface diffusion. Contrary to the simple RSA case, generalized RSA processes are no longer irreversible and the system formed by the adsorbed particles on the surface may reach an equilibrium state. We show by using a distribution function approach that the kinetics of such processes can be described by means of an exact infinite hierarchy of equations reminiscent of the Kirkwood-Salsburg hierarchy for systems at equilibrium. We illustrate the way in which the systems produced by adsorption/desorption and by adsorption/diffusion evolve between the two limits represented by ``simple RSA'' and ``equilibrium'' by considering approximate solutions in terms of truncated density expansions.

  11. 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.

  12. Differences in absorption, distribution, metabolism and excretion of xenobiotics between the paediatric and adult populations.

    PubMed

    Strolin Benedetti, M; Whomsley, R; Baltes, E L

    2005-10-01

    In children, the therapeutic benefits and potential risks associated with drug treatment may be different from those in adults and will depend on the exposure, receptor sensitivity and relationship between effect and exposure. In this paper, key factors undergoing maturational changes accounting for differences in drug metabolism and disposition in the paediatric population compared with adults are reviewed. Gastric and duodenal pH, gastric emptying time, intestinal transit time, secretion and activity of bile and pancreatic fluid, bacterial colonisation and transporters, such as P-glycoprotein (P-gp), are important factors for drug absorption, whereas key factors explaining differences in drug distribution between the paediatric population and adults are organ size, membrane permeability, plasma protein concentration and characteristics, endogenous substances in plasma, total body and extracellular water, fat content, regional blood flow and transporters such as P-gp, which is present not only in the gut, but also in liver, kidney, brain and other tissues. As far as drug metabolism is concerned, important differences have been found in the paediatric population compared with adults both for phase I enzymes (oxidative [e.g., cytochrome P450 (CYP)1A2, and CYP3A7 versus -3A4], reductive and hydrolytic enzymes) and phase II enzymes (e.g., N-methyltransferases and glucuronosyltransferases). Generally, the major enzyme differences observed in comparison with the adult age are in newborn infants, although for some enzymes (e.g., glucuronosyltransferases and other phase II enzymes) important differences still exist between infants and toddlers and adults. Finally, key factors undergoing maturational changes accounting for differences in renal excretion in the paediatric population compared with adults are glomerular filtration and tubular secretion. The ranking of the key factors varies according to the chemical structure and physicochemical properties of the drug

  13. Walking with a Backpack using Load Distribution and Dynamic Load Compensation Reduces Metabolic Cost and Adaptations to Loads.

    PubMed

    Park, Joon-Hyuk; Stegall, Paul; Zhang, Haohan; Agrawal, Sunil

    2016-11-09

    In this study, we showed a way of reducing the metabolic cost of walking with a backpack using load distribution and dynamic load compensation, provided by a wearable upper body device. This device distributes the backpack load between the shoulders and the pelvis, senses the vertical motion of the pelvis, and provides gait synchronized compensatory forces to reduce the dynamic loads from a backpack. It was hypothesized that by reducing dynamic loads from a backpack during load carriage, the users gait and postural adaptation, muscular effort and metabolic cost would be reduced. This hypothesis was supported by biomechanical and physiological measurements on a group of young healthy subjects, as they walked on a treadmill under 4 different conditions: unloaded; with a backpack, loaded with 25% of their body weight, supported on the shoulders; with the same load distributed between the shoulders and the pelvis; and with dynamic load compensation in addition to load distribution. The results showed reductions in gait and postural adaptations, muscle activity, vertical and braking ground reaction forces, and metabolic cost while carrying the same backpack load with the device. We conclude that the device can potentially reduce the risk of musculoskeletal injuries and muscle fatigue associated with carrying heavy backpack loads while reducing the metabolic cost of loaded walking.

  14. 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.

  15. 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.

  16. Phylogenetic distributions and histories of proteins involved in anaerobic pyruvate metabolism in eukaryotes.

    PubMed

    Hug, Laura A; Stechmann, Alexandra; Roger, Andrew J

    2010-02-01

    Protists that live in low oxygen conditions often oxidize pyruvate to acetate via anaerobic ATP-generating pathways. Key enzymes that commonly occur in these pathways are pyruvate:ferredoxin oxidoreductase (PFO) and [FeFe]-hydrogenase (H(2)ase) as well as the associated [FeFe]-H(2)ase maturase proteins HydE, HydF, and HydG. Determining the origins of these proteins in eukaryotes is of key importance to understanding the origins of anaerobic energy metabolism in microbial eukaryotes. We conducted a comprehensive search for genes encoding these proteins in available whole genomes and expressed sequence tag data from diverse eukaryotes. Our analyses of the presence/absence of eukaryotic PFO, [FeFe]-H(2)ase, and H(2)ase maturase sequences across eukaryotic diversity reveal orthologs of these proteins encoded in the genomes of a variety of protists previously not known to contain them. Our phylogenetic analyses revealed: 1) extensive lateral gene transfers of both PFO and [FeFe]-H(2)ase in eubacteria, 2) decreased support for the monophyly of eukaryote PFO domains, and 3) that eukaryotic [FeFe]-H(2)ases are not monophyletic. Although there are few eukaryote [FeFe]-H(2)ase maturase orthologs characterized, phylogenies of these proteins do recover eukaryote monophyly, although a consistent eubacterial sister group for eukaryotic homologs could not be determined. An exhaustive search for these five genes in diverse genomes from two representative eubacterial groups, the Clostridiales and the alpha-proteobacteria, shows that although these enzymes are nearly universally present within the former group, they are very rare in the latter. No alpha-proteobacterial genome sequenced to date encodes all five proteins. Molecular phylogenies and the extremely restricted distribution of PFO, [FeFe]-H(2)ases, and their associated maturases within the alpha-proteobacteria do not support a mitochondrial origin for these enzymes in eukaryotes. However, the unexpected prevalence of PFO

  17. Plasma clearance, tissue distribution and metabolism of hyaluronic acid injected intravenously in the rabbit.

    PubMed Central

    Fraser, J R; Laurent, T C; Pertoft, H; Baxter, E

    1981-01-01

    The plasma clearance, tissue distribution and metabolism of hyaluronic acid were studied with a high average molecular weight [3H]acetyl-labelled hyaluronic acid synthesized in synovial cell cultures. After intravenous injection in the rabbit the label disappeared from the plasma with a half-life of 2.5--4.5 min, which corresponds to a normal hyaluronic acid clearance of approx. 10 mg/day per kg body weight. Injection of unlabelled hyaluronic acid 15 min after the tracer failed to reverse its absorption. Clearance of labelled polymer was retarded by prior injection of excess unlabelled hyaluronic acid. The maximum clearance capacity was estimated in these circumstances to be about 30 mg/day per kg body wt. The injected material was concentrated in the liver and spleen. As much as 88% of the label was absorbed by the liver, where it was found almost entirely in non-parenchymal cells. Degradation was rapid and complete, since volatile material, presumably 3H2O, appeared in the plasma within 20 min. Undegraded [3H]hyaluronic acid, small labelled residues and 3H2O were detected in the liver, but there was little evidence of intermediate oligosaccharides. No metabolite except 3H2O was recognized in plasma or urine. Two-thirds of the radioactivity was retained in the body water 24 h later, and small amounts were found in liver lipids. Radioactivity did not decline in the spleen as rapidly as in the liver. The upper molecular weight limit for renal excretion was about 25 000. Renal excretion played a negligible part in clearance. It is concluded that hyaluronic acid is removed from the plasma and degraded quickly by an efficient extrarenal system with a high reserve capacity, sited mainly in the liver. PMID:7340841

  18. 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

  19. Chemistry, distribution, and metabolism of tomato carotenoids and their impact on human health.

    PubMed

    Khachik, Frederick; Carvalho, Lorena; Bernstein, Paul S; Muir, Garth J; Zhao, Da-You; Katz, Nikita B

    2002-11-01

    Recent epidemiological studies have suggested that the consumption of tomatoes and tomato-based food products reduce the risk of prostate cancer in humans. This protective effect has been attributed to carotenoids, which are one of the major classes of phytochemicals in this fruit. The most abundant carotenoid in tomato is lycopene, followed by phytoene, phytofluene, zeta-carotene, gamma-carotene, beta-carotene, neurosporene, and lutein. The distribution of lycopene and related carotenoids in tomatoes and tomato-based food products has been determined by extraction and high-performance liquid chromatography-UV/Visible photodiode array detection. Detailed qualitative and quantitative analysis of human serum, milk, and organs, particularly prostate, have revealed the presence of all the aforementioned carotenoids in biologically significant concentrations. Two oxidative metabolites of lycopene, 2,6-cyclolycopene-1,5-diols A and B, which are only present in tomatoes in extremely low concentrations, have been isolated and identified in human serum, milk, organs (liver, lung, breast, liver, prostate, colon) and skin. Carotenoids may also play an important role in the prevention of age-related macular degeneration, cataracts, and other blinding disorders. Among 25 dietary carotenoids and nine metabolites routinely found in human serum, mainly (3R,3'R,6'R)-lutein, (3R,3'R)-zeaxanthin, lycopene, and their metabolites were detected in ocular tissues. In this review we identified and quantified the complete spectrum of carotenoids from pooled human retinal pigment epithelium, ciliary body, iris, lens, and in the uveal tract and in other tissues of the human eye to gain a better insight into the metabolic pathways of ocular carotenoids. Although (3R,3'R,6'R)-lutein, (3R,3'R)-zeaxanthin, and their metabolites constitute the major carotenoids in human ocular tissues, lycopene and a wide range of dietary carotenoids have been detected in high concentrations in ciliary body and

  20. Time-dependent movement and distribution of chlorpyrifos and its metabolism in bamboo forest under soil surface mulching.

    PubMed

    Liu, Yihua; Shen, Danyu; Zhong, Donglian; Mo, Runhong; Ni, Zhanglin; Tang, Fubin

    2014-07-16

    The dissipation and distribution of chlorpyrifos (CHP) granule formulation in bamboo forest under soil surface mulching conditions (CP) and noncovered cultivation conditions (NCP) from soil to product were investigated. In the CP treatment, the CHP granule with slow-release effect leached from the topsoil to the subsoil. Conversely, the CHP was fixed in the topsoil (0-5 cm layer) in the NCP treatment, and no obvious leaching effect could be observed. The residue of CHP could be found in bamboo shoots from CP treatment, mainly at the bottom part (5 cm length). CHP could be degraded into 3,5,6-trichloro-2-pyridinol (TCP) in the soil and bamboo shoots. In addition, the straw used as the mulching material with higher OM and pH had some regulatory role in changing the pH and OM characteristics of the soil. Thus the straw could indirectly affect the adsorption and degradation behavior of CHP and TCP in the soil.

  1. Distribution, metabolism and excretion of a synthetic androgen 7alpha-methyl-19-nortestosterone, a potential male-contraceptive.

    PubMed

    Prasad, Pramod Vishwanath; Arumugam, Ramamani; Willman, Mark; Ge, Ren-Shan; Sitruk-Ware, Regine; Kumar, Narender

    2009-01-01

    A synthetic androgen 7alpha-Methyl-19-nortestosterone (MENT) has a potential for therapeutic use in 'androgen replacement therapy' for hypogonadal men or as a hormonal male-contraceptive in normal men. Its tissue distribution, excretion and metabolic enzyme(s) have not been reported. Therefore, the present study tested the distribution and excretion of MENT in Sprague-Dawley rats castrated 24h prior to the injection of tritium-labeled MENT ((3)H-MENT). Rats were euthanized at different time intervals after dosing, and the amount of radioactivity in various tissues/organs was measured following combustion in a Packard oxidizer. The radioactivity (% injected dose) was highest in the duodenal contents in the first 30min of injection. Specific uptake of the steroid was observed in target tissues such as ventral prostate and seminal vesicles at 6h, while in other tissues radioactivity equilibrated with blood. Liver and duodenum maintained high radioactivity throughout, as these organs were actively involved in the metabolism and excretion of most drugs. The excretion of (3)H-MENT was investigated after subcutaneous injection of (3)H-MENT into male rats housed in metabolic cages. Urine and feces were collected at different time intervals (up to 72h) following injection. Results showed that the radioactivity was excreted via feces and urine in equal amounts by 30h. Aiming to identify enzyme(s) involved in the MENT metabolism, we performed in vitro metabolism of (3)H-MENT using rat and human liver microsomes, cytosol and recombinant cytochrome P(450) (CYP) isozymes. The metabolites were separated by thin-layer chromatography (TLC). Three putative metabolites (in accordance with the report of Agarwal and Monder [Agarwal AK, Monder C. In vitro metabolism of 7alpha-methyl-19-nortestosterone by rat liver, prostate, and epididymis. Endocrinology 1988;123:2187-93]), [i] 3-hydroxylated MENT by both rat and human liver cytosol; [ii] 16alpha-hydroxylated MENT (a polar metabolite

  2. 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.

  3. 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.

  4. CO2 Metabolism in Corn Roots. II. Intracellular Distribution of Enzymes 1

    PubMed Central

    Danner, Jean; Ting, Irwin P.

    1967-01-01

    Three enzymes assumed to mediate CO2 metabolism in corn root tips, P-enolpyruvate carboxylase, malic dehydrogenase, and the malic enzyme, were extracted to determine their relative specific activities and their partitioning between soluble and particulate fractions. The data indicated that the intracellular location of these 3 enzymes is nonparticulate and thus these enzymatic reactions of CO2 metabolism are apparently nonparticulate. The soluble malic dehydrogenase fraction differed from the particulate fraction in several kinetic properties, viz., response to the thionicotinamide analog of nicotinamide-adenine dinucleotide, oxaloacetate substrate inhibition at pH 8.3, and Km's for nicotinamide-adenine dinucleotide and l-malate. It was concluded that the soluble-malic dehydrogenase differed from the particulate forms in both structure and function. The soluble malic dehydrogenase is apparently involved in CO2 metabolism. PMID:16656561

  5. Étude par chromatographie gazeuse inverse, à concentration finie, des propriétés de surface d'échantillons obtenus par traitement thermique de la goethite : distribution des sites d'adsorption des alcanes

    NASA Astrophysics Data System (ADS)

    Brendlé, E.; Balard, H.; Papirer, E.

    1998-07-01

    Inverse Gas Chromatography (IGC), at finite concentration conditions, was applied for the evaluation of the surface properties of hematite samples obtained by heat treatment of goethite. From the alkane adsorption isotherms, the distribution of surface sites according to the adsorption energy is determined. It is shown that the surface of hematite undergoes significant changes when heated up to 500 circC. La chromatographie Gazeuse Inverse (CGI), à concentration finie, a été utilisée pour évaluer les propriétés de surface d'échantillons d'hématite obtenus par traitement thermique de la goethite. A partir des isothermes d'adsorption des alcanes, on détermine la courbe de distribution des sites de surface en fonction de l'énergie d'adsorption de molécules sondes. On montre que ces courbes évoluent en fonction du traitement thermique de la goethite et traduisent une importante modification de surface de l'hématite formée après un chauffage à 500 circC.

  6. Amino acid distribution and metabolism in pituitary adenomas using positron emission tomography with D-(/sup 11/C)methionine and L-(/sup 11/C)methionine

    SciTech Connect

    Bergstroem, M.M.; Muhr, C.; Lundberg, P.O.; Bergstroem, K.L.; Lundqvist, H.; Antoni, G.; Fasth, K.J.; Langstroem B3

    1987-05-01

    Four patients with hormonally inactive pituitary adenomas were examined with positron emission tomography (PET) after injection, during different examinations, of L-(methyl-/sup 11/C)methionine and D-(methyl-/sup 11/C)methionine, respectively. After the rapid distribution phase, the enantiomer L-(/sup 11/C)methionine, which is metabolically active, showed a considerable continuous irreversible trapping attributed to amino acid metabolism. The stereoisomer D-(/sup 11/C)methionine, which does not participate in protein synthesis, showed a rapid distribution within the whole adenoma tissue, with a distribution space on the order of 100%. A minimal irreversible trapping was observed which could be explained by technical factors. It is concluded that PET using the two enantiomers allows a separation of passive distribution and metabolism, and that L-(/sup 11/C)methionine can be used for in vivo quantitative studies of amino acid metabolism of pituitary adenomas.

  7. 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

  8. Metabolic flexibility as a major predictor of spatial distribution in microbial communities.

    PubMed

    Carbonero, Franck; Oakley, Brian B; Purdy, Kevin J

    2014-01-01

    A better understand the ecology of microbes and their role in the global ecosystem could be achieved if traditional ecological theories can be applied to microbes. In ecology organisms are defined as specialists or generalists according to the breadth of their niche. Spatial distribution is often used as a proxy measure of niche breadth; generalists have broad niches and a wide spatial distribution and specialists a narrow niche and spatial distribution. Previous studies suggest that microbial distribution patterns are contrary to this idea; a microbial generalist genus (Desulfobulbus) has a limited spatial distribution while a specialist genus (Methanosaeta) has a cosmopolitan distribution. Therefore, we hypothesise that this counter-intuitive distribution within generalist and specialist microbial genera is a common microbial characteristic. Using molecular fingerprinting the distribution of four microbial genera, two generalists, Desulfobulbus and the methanogenic archaea Methanosarcina, and two specialists, Methanosaeta and the sulfate-reducing bacteria Desulfobacter were analysed in sediment samples from along a UK estuary. Detected genotypes of both generalist genera showed a distinct spatial distribution, significantly correlated with geographic distance between sites. Genotypes of both specialist genera showed no significant differential spatial distribution. These data support the hypothesis that the spatial distribution of specialist and generalist microbes does not match that seen with specialist and generalist large organisms. It may be that generalist microbes, while having a wider potential niche, are constrained, possibly by intrageneric competition, to exploit only a small part of that potential niche while specialists, with far fewer constraints to their niche, are more capable of filling their potential niche more effectively, perhaps by avoiding intrageneric competition. We suggest that these counter-intuitive distribution patterns may be a

  9. Astroglial distribution and sexual differences in neural metabolism in mammillary bodies.

    PubMed

    Blanco, Eduardo; Picón, Isabel M; Miranda, Ruben; Begega, Azucena; Conejo, Nélida M; Arias, Jorge L

    2006-02-27

    The sexual differences in cerebral nuclei are produced by the organizational and the activational function of gonadal hormones. The different performances by male and female rats in memory tasks requiring use of the mammillary bodies (MBs), could be due to structural and functional sexual dimorphic differences. Our work quantifies the number of glial fibrillary acidic protein immunoreactive (GFAP-IR) astrocytes, and neuronal metabolic activity measured by the cytochrome oxidase (CO) histochemistry in the MBs in rats of both sexes. We find that there is no difference in astroglial number in the medial mammillary nucleus (MMN) and in the lateral mammillary nucleus (LMN) of males, females in estrus and diestrus adult rats. However, we do find statistically significant differences between the sexes in the neuronal oxidative metabolism influenced by the estrous cycle. We, therefore, conclude that there are functional and not structural sex differences in the MBs.

  10. Comparison of distribution and metabolism between tellurium and selenium in rats.

    PubMed

    Ogra, Yasumitsu; Kobayashi, Reina; Ishiwata, Kazuya; Suzuki, Kazuo T

    2008-07-01

    Tellurium (Te) has shown recent increase in use as a component of optical magnetic disks having phase-change property, such as digital versatile disk-random access memory (DVD-RAM) and DVD-rewritable (DVD-RW). However, the toxicity and metabolic pathway of Te remain unclear despite its being known as a non-essential and harmful metalloid. This study was performed to gain an insight into Te metabolism in the body. The mechanism for the distinction of Te from selenium (Se), an essential metalloid belonging to the same group as Te, was also clarified. Rats were given drinking water containing tellurite and (82)Se-labeled selenite at the same concentration, and the concentrations of these metalloids in organs, body fluid and excreta were determined 2 days later. The results demonstrate that urinary and fecal excretion of Te was, respectively, lower and higher than that of exogenous (labeled) Se, suggesting that Te was less absorbed than Se. The ingested Te was transformed, i.e., methylated in organs and effluxed into bloodstream, and the effluxed Te was highly accumulated in rat red blood cells (RBCs) in the form of dimethylated Te. In contrast, Se was not accumulated in RBCs. Finally, Te was excreted in urine as trimethyltelluronium and might be exhaled as dimethyltelluride. The results suggest that the metabolism of Te was distinct from that of Se in rats.

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

    PubMed

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

    2015-04-01

    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.

  12. 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

  13. Imepitoin as novel treatment option for canine idiopathic epilepsy: pharmacokinetics, distribution, and metabolism in dogs

    PubMed Central

    Rundfeldt, C; Gasparic, A; Wlaź, P

    2014-01-01

    Imepitoin is a novel anti-epileptic licensed in the European Union for the treatment of canine idiopathic epilepsy. The aim of this study was to characterize the pharmacokinetics of imepitoin in dogs and to evaluate the interaction with drug metabolizing enzymes. Upon administration of imepitoin tablets at a dose of 30 mg/kg to beagle dogs, high plasma levels were observed within 30 min following oral dosing, with maximal plasma concentrations of 14.9–17.2 μg/mL reached after 2–3 h. In a crossover study, co-administration of imepitoin tablets with food reduced the total AUC by 30%, but it did not result in significant changes in Tmax and Cmax, indicating lack of clinical relevance. No clinically relevant effects of sex and no accumulation or metabolic tolerance were observed upon twice daily dosing. Following single dose administration of 10–100 mg/kg, dose linearity was found. Administering [14C] imepitoin, high enteral absorption of 92% and primary fecal excretion were identified. Plasma protein binding was only 55%. At therapeutic plasma concentrations, imepitoin did not inhibit microsomal cytochrome P450 family liver enzymes in vitro. In rats, no relevant induction of liver enzymes was found. Therefore, protein binding or metabolism-derived drug–drug interactions are unlikely. Based on these data, imepitoin can be dosed twice daily, but the timing of tablet administration in relation to feeding should be kept consistent. PMID:24611573

  14. Influence of alternative cations distribution in AgxLi96-x-LSX on dehydration kinetics and its selective adsorption performance for N2 and O2

    NASA Astrophysics Data System (ADS)

    Panezai, Hamida; Sun, Jihong; Jin, Xiaoqi

    2016-12-01

    Adsorption characteristics of pure gases N2 and O2 on various silver exchanged low silica X-type (AgxLi96-x-LSX) zeolites were investigated. The equilibrium adsorption isotherms of N2 and O2 were measured at 273 and 298 K. Textual and structural properties of parent and resultant AgxLi96-x-LSX were characterized by XRD, BET surface area, and SEM techniques. Kinetics of their thermal dehydration were studied by exploiting thermogravimetric and differential data (TG-DTG) obtained at three heating rates (5, 10 and 15 K) using two model-free (Kissinger and Flynn-Wall-Ozawa) and one model fitting (Coats-Redfern) methods. Forty one mechanism functions were used to evaluate kinetic triplet (activation energy, frequency factor, and most probable mechanism/model) for different stages of dehydration. Results revealed that the impact of very small content of silver on the adsorption of N2 is pronounced and attributed to weak chemical bonds formed between N2 and Ag+ clusters due to strong adsorption of N2 at low pressure, whereas O2 adsorption is affected to a negligible extent. In addition, the N2/O2 adsorption selectivity shows unexpected low values for Ag87.08Li7.94Na0.98-LSX with higher Ag+ content (91.00 %), which might be due to low crystalline water content as well as Ag+ clusters located at SIII sites. N2 adsorption strongly depends on temperature as higher adsorption occurs at low temperature 273 K as compared to 298 K.

  15. Laboratory study on the adsorption of Mn(2+) on suspended and deposited amorphous Al(OH)(3) in drinking water distribution systems.

    PubMed

    Wang, Wendong; Zhang, Xiaoni; Wang, Hongping; Wang, Xiaochang; Zhou, Lichuan; Liu, Rui; Liang, Yuting

    2012-09-01

    Manganese (II) is commonly present in drinking water. This paper mainly focuses on the adsorption of manganese on suspended and deposited amorphous Al(OH)(3) solids. The effects of water flow rate and water quality parameters, including solution pH and the concentrations of Mn(2+), humic acid, and co-existing cations on adsorption were investigated. It was found that chemical adsorption mainly took place in drinking water with pHs above 7.5; suspended Al(OH)(3) showed strong adsorption capacity for Mn(2+). When the total Mn(2+) input was 3 mg/L, 1.0 g solid could accumulate approximately 24.0 mg of Mn(2+) at 15 °C. In drinking water with pHs below 7.5, because of H(+) inhibition, active reaction sites on amorphous Al(OH)(3) surface were much less. The adsorption of Mn(2+) on Al(OH)(3) changed gradually from chemical coordination to physical adsorption. In drinking water with high concentrations of Ca(2+), Mg(2+), Fe(3+), and HA, the removal of Mn(2+) was enhanced due to the effects of co-precipitation and adsorption. In solution with 1.0 mg/L HA, the residual concentration of Mn(2+) was below 0.005 mg/L, much lower than the limit value required by the Chinese Standard for Drinking Water Quality. Unlike suspended Al(OH)(3), deposited Al(OH)(3) had a much lower adsorption capacity of 0.85 mg/g, and the variation in flow rate and major water quality parameters had little effect on it. Improved managements of water age, pipe flushing and mechanical cleaning were suggested to control residual Mn(2+).

  16. 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.

  17. 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

  18. 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.

  19. The evolution of high summit metabolism and cold tolerance in birds and its impact on present-day distributions.

    PubMed

    Swanson, David L; Garland, Theodore

    2009-01-01

    Summit metabolic rate (M(sum), maximum cold-induced metabolic rate) is positively correlated with cold tolerance in birds, suggesting that high M(sum) is important for residency in cold climates. However, the phylogenetic distribution of high M(sum) among birds and the impact of its evolution on current distributions are not well understood. Two potential adaptive hypotheses might explain the phylogenetic distribution of high M(sum) among birds. The cold adaptation hypothesis contends that species wintering in cold climates should have higher M(sum) than species wintering in warmer climates. The flight adaptation hypothesis suggests that volant birds might be capable of generating high M(sum) as a byproduct of their muscular capacity for flight; thus, variation in M(sum) should be associated with capacity for sustained flight, one indicator of which is migration. We collected M(sum) data from the literature for 44 bird species and conducted both conventional and phylogenetically informed statistical analyses to examine the predictors of M(sum) variation. Significant phylogenetic signal was present for log body mass, log mass-adjusted M(sum), and average temperature in the winter range. In multiple regression models, log body mass, winter temperature, and clade were significant predictors of log M(sum). These results are consistent with a role for climate in determining M(sum) in birds, but also indicate that phylogenetic signal remains even after accounting for associations indicative of adaptation to winter temperature. Migratory strategy was never a significant predictor of log M(sum) in multiple regressions, a result that is not consistent with the flight adaptation hypothesis.

  20. Biochemical and metabolic abnormalities in articular cartilage from osteoarthritic human hips. III. Distribution and metabolism of amino sugar-containing macromolecules.

    PubMed

    Mankin, H J; Johnson, M E; Lippiello, L

    1981-01-01

    Since 1960, numerous studies have supported the thesis that the synthetic activity of articular chondrocytes is increased in osteoarthritis, but several recent reports have challenged this concept. To clarify this problem fully and also to define further the products of this increased synthesis, three experiments were performed in which the distribution and rates of synthesis of amino sugar-containing macromolecules in normal and osteoarthritic cartilage from the human femoral head were assessed by biochemical analysis and studies of the incorporation of 3H-glucosamine and 35SO4. The biochemical data obtained clearly demonstrated the previously noted significant decrease in hexosamine content in osteoarthritic tissue. This decrease was principally due to a diminution in glucosamine concentration and correlated inversely with the severity of the disease process (as measured by a previously described histological-histochemical grading system). Metabolic studies showed a marked increment in the rates of incorporation of 3H-glucosamine into both the glucosamine and the galactosamine fractions of the cartilage. The increased synthesis correlated directly in a non-linear fashion with the severity of the disease. The ratio of the rate of incorporation of 3H-glucosamine into the glucosamine fraction to the rate of its incorporation into the galactosamine fraction was the same in normal and osteoarthritic samples, suggesting that the decline in glucosamine concentration was not related to a qualitative alteration of synthetic activity.

  1. Conceptual adsorption models and open issues pertaining to performance assessment

    SciTech Connect

    Serne, R.J.

    1991-10-01

    Recently several articles have been published that question the appropriateness of the distribution coefficient, Rd, concept to quantify radionuclide migration. Several distinct issues are raised by various critics. In this paper I provide some perspective on issues surrounding the modeling of nuclide retardation. The first section defines adsorption terminology and discusses various adsorption processes. The next section describes five commonly used adsorption conceptual models, specifically emphasizing what attributes that affect adsorption are explicitly accommodated in each model. I also review efforts to incorporate each adsorption model into performance assessment transport computer codes. The five adsorption conceptual models are (1) the constant Rd model, (2) the parametric Rd model, (3) isotherm adsorption models, (4) mass-action adsorption models, and (5) surface-complexation with electrostatics models. The final section discusses the adequacy of the distribution ratio concept, the adequacy of transport calculations that rely on constant retardation factors and the status of incorporating sophisticated adsorption models into transport codes.

  2. Spatial distribution of osteocyte lacunae in equine radii and third metacarpals: considerations for cellular communication, microdamage detection and metabolism.

    PubMed

    Skedros, John G; Grunander, Todd R; Hamrick, Mark W

    2005-01-01

    Osteocytes, which are embedded in bone matrix, are the most abundant cells in bone. Despite the ideal location of osteocytes to sense the local environment and influence bone remodeling, their functions, and the relative importance of these functions, remain controversial. In this study, we tested several hypotheses that address the possibilities that population densities of osteocyte lacunae (Ot.Lc.N/B.Ar) correlate with strain-, remodeling- or metabolism-related aspects of the local biomechanical environments of mid-third diaphyseal equine radii and third metacarpals from skeletally mature animals. Ot.Lc.N/B.Ar data, quantified in multiple cortical locations, were analyzed for possible correlations with (1) structural and material characteristics (e.g., cortical thickness, percent ash, secondary osteon population density, mean osteon cross-sectional area, and predominant collagen fiber orientation), (2) strain characteristics, including prevalent/predominant strain magnitude and mode (tension, compression, shear), (3) hypothesized strain-mode-related microdamage characteristics, which might be perceived by osteocyte 'operational' networks, and (4) variations in remodeling dynamics and/or metabolism (i.e. presumably higher in endocortical regions than in other transcortical locations). Results showed relatively uniform Ot.Lc.N/B.Ar between regions with highly non-uniform strain and strain-related environments and markedly heterogeneous structural and material organization. These results suggest that population densities of these cells are poorly correlated with mechanobiological characteristics, including local variations in metabolic rate and strain magnitude/mode. Although osteocytes hypothetically evolved both as strain sensors and fatigue damage sensors able to direct the removal of damage as needed, the mechanisms that govern the distribution of these cells remain unclear. The results of this study provide little or no evidence that the number of osteocyte

  3. Distribution of bacterioplankton with active metabolism in waters of the St. Anna Trough, Kara Sea, in autumn 2011

    NASA Astrophysics Data System (ADS)

    Mosharova, I. V.; Mosharov, S. A.; Ilinskiy, V. V.

    2017-01-01

    The distribution of bacterioplankton with active electron transport chains, as well as bacteria with intact cell membranes, was investigated for the first time in the region of St. Anna Trough in the Kara Sea. The average number of bacteria with active electron transport chains in the waters of the St. Anna Trough was 15.55 × 103 cells mL-1 (the limits of variation were 1.06-92.17 × 103 cells mL-1). The average number of bacteria with intact membranes was 33.46 × 103 cells mL-1 (the limits of variation were 6.78 to 103.18 × 103 cells mL-1). Almost all bacterioplankton microorganisms in the studied area were potentially viable, and the average share of bacteria with intact membranes was 92.1% of the total number of bacterioplankton (TNB) (the limits of variation were 76.2 to 98.4%). The share of bacteria with active metabolisms was 38.2% of the TNB (the limits of variation were 5.6-93.4%). The shares of the bacteria with active metabolisms were maximum in areas with the most stable environmental conditions (on the shelf and in deep water), whereas on the slope, where the gradients of water temperature and salinity were maximum, these values were lower.

  4. The effects of smoltification on the uptake, distribution and metabolism of benzo[a]pyrene in coho salmon

    SciTech Connect

    Lemke, M.A.; Kennedy, C.J.

    1995-12-31

    Benzo[a]pyrene uptake, distribution and metabolism patterns were investigated from February to June during the transformation of freshwater coho salmon (Oncorhynchus kisutch) liparr to smolts. At a constant benzo[a]pyrene concentration of 5ug/L, BaP uptake rates increased from 0.01 ug-h{sup {minus}1}-g{sup {minus}1} in February to 0.04 ug-h{sup {minus}1}-g{sup {minus}1} in May and declined to 0.03 ug-h{sup {minus}1}-g{sup {minus}1} in June. Following a 24 hour exposure, the accumulation of BaP in the liver, gills, visceral fat and kidney increased from February to May and declined to June. This pattern appeared to be due to changes in BaP uptake rates. In contrast, the percent body burden in bile remained low (20--25%) until the end of May when it increased to 45-50%. The amounts of BaP in the tissues such as stomach, intestine, skin, muscle, and brain did not show significant differences throughout the study. An analysis of bile suggested that coho salmon parr and smolts are capable of metabolizing benzo[a]pyrene via Phase 1 and Phase 2 transformation reactions to glucuronide, sulfate and possibly glutathione conjugates. The majority of BaP metabolites in the bile were unidentified water-soluble compounds.

  5. 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.

  6. Subcellular Distribution of NAD+ between Cytosol and Mitochondria Determines the Metabolic Profile of Human Cells.

    PubMed

    VanLinden, Magali R; Dölle, Christian; Pettersen, Ina K N; Kulikova, Veronika A; Niere, Marc; Agrimi, Gennaro; Dyrstad, Sissel E; Palmieri, Ferdinando; Nikiforov, Andrey A; Tronstad, Karl Johan; Ziegler, Mathias

    2015-11-13

    The mitochondrial NAD pool is particularly important for the maintenance of vital cellular functions. Although at least in some fungi and plants, mitochondrial NAD is imported from the cytosol by carrier proteins, in mammals, the mechanism of how this organellar pool is generated has remained obscure. A transporter mediating NAD import into mammalian mitochondria has not been identified. In contrast, human recombinant NMNAT3 localizes to the mitochondrial matrix and is able to catalyze NAD(+) biosynthesis in vitro. However, whether the endogenous NMNAT3 protein is functionally effective at generating NAD(+) in mitochondria of intact human cells still remains to be demonstrated. To modulate mitochondrial NAD(+) content, we have expressed plant and yeast mitochondrial NAD(+) carriers in human cells and observed a profound increase in mitochondrial NAD(+). None of the closest human homologs of these carriers had any detectable effect on mitochondrial NAD(+) content. Surprisingly, constitutive redistribution of NAD(+) from the cytosol to the mitochondria by stable expression of the Arabidopsis thaliana mitochondrial NAD(+) transporter NDT2 in HEK293 cells resulted in dramatic growth retardation and a metabolic shift from oxidative phosphorylation to glycolysis, despite the elevated mitochondrial NAD(+) levels. These results suggest that a mitochondrial NAD(+) transporter, similar to the known one from A. thaliana, is likely absent and could even be harmful in human cells. We provide further support for the alternative possibility, namely intramitochondrial NAD(+) synthesis, by demonstrating the presence of endogenous NMNAT3 in the mitochondria of human cells.

  7. 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.

  8. Novel tryptophan metabolism by a potential gene cluster that is widely distributed among actinomycetes.

    PubMed

    Ozaki, Taro; Nishiyama, Makoto; Kuzuyama, Tomohisa

    2013-04-05

    The characterization of potential gene clusters is a promising strategy for the identification of novel natural products and the expansion of structural diversity. However, there are often difficulties in identifying potential metabolites because their biosynthetic genes are either silenced or expressed only at a low level. Here, we report the identification of a novel metabolite that is synthesized by a potential gene cluster containing an indole prenyltransferase gene (SCO7467) and a flavin-dependent monooxygenase (FMO) gene (SCO7468), which were mined from the genome of Streptomyces coelicolor A3(2). We introduced these two genes into the closely related Streptomyces lividans TK23 and analyzed the culture broths of the transformants. This process allowed us to identify a novel metabolite, 5-dimethylallylindole-3-acetonitrile (5-DMAIAN) that was overproduced in the transformant. Biochemical characterization of the recombinant SCO7467 and SCO7468 demonstrated the novel L-tryptophan metabolism leading to 5-DMAIAN. SCO7467 catalyzes the prenylation of L-tryptophan to form 5-dimethylallyl-L-tryptophan (5-DMAT). This enzyme is the first actinomycetes prenyltransferase known to catalyze the addition of a dimethylallyl group to the C-5 of tryptophan. SCO7468 then catalyzes the conversion of 5-DMAT into 5-dimethylallylindole-3-acetaldoxime (5-DMAIAOx). An aldoxime-forming reaction catalyzed by the FMO enzyme was also identified for the first time in this study. Finally, dehydration of 5-DMAIAOx presumably occurs to yield 5-DMAIAN. This study provides insight into the biosynthesis of prenylated indoles that have been purified from actinomycetes.

  9. Distribution, Metabolism and Toxic Effects of Beta-Cypermethrin in Lizards (Eremias argus) Following Oral Administration.

    PubMed

    Chen, Li; Xu, Peng; Diao, Jinling; Di, Shanshan; Li, Ruiting; Zhou, Zhiqiang

    2016-04-05

    Beta-cypermethrin (BCYP), a synthetic pyrethriod (PYR) pesticide which is a mixture of the alpha- and theta- cypermethrin, have been reported various toxicological profiles to non-target organisms. But little is known about assimilation, accumulation and toxic effects of BCYP in reptiles. The present study firstly elucidated absorption, tissue distribution, excretion of BCYP in Eremias argus . Treated group were administered orally with BCYP 20mg/kg body weight (bw) dissolved in corn oil. Neurotoxicity was observed at 24h after gavage, and the poisoning symptom ameliorated at 72h. The changes of BCYP concentration depended on degradation time and tissues. Lizards had a strong capacity to eliminate BCYP with different tissue distribution. The tissues concentration of BCYP from high to low were intestine, stomach, heart, kidney, blood, lung, liver and brain. Bimodal phenomena were observed in lung, liver and kidney. These results may be due to the activities of enzymes, circadian rhythm, and enterohepatic circulation in lizards. Based on the results of organ coefficient and histopathology analysis in liver, the liver was confirmed as the main target organ.

  10. How Surface Heterogeneity Affects Protein Adsorption: Annealing of OTS Patterns and Albumin Adsorption Kinetics*

    PubMed Central

    Hodgkinson, Gerald N.; Hlady, Vladimir

    2009-01-01

    Fluorescence microscopy and intensity histogram analysis techniques were used to monitor spatially-resolved albumin adsorption kinetics to model heterogeneous surfaces on sub-μm scales. Several distinct protein subpopulations were resolved, each represented by a normal distribution of adsorption densities on the adsorbent surface. Histogram analyses provided dynamic information of mean adsorption density, spread in adsorption density, and surface area coverage for each distinct protein subpopulation. A simple adsorption model is proposed in which individual protein binding events are predicted by the summation of multiple protein's surface sub-site interactions with different binding energy sub-sites on adsorbent surfaces. This model is predictive of the albumin adsorption on the patterns produced by one step μ-contact printing (μCP) of octadecyltrichlorosilane (OTS) on glass but fails to describe adsorption once the same patterns are altered by a thermal annealing step. PMID:19746205

  11. 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

  12. 13C-Tracer and Gas Chromatography-Mass Spectrometry Analyses Reveal Metabolic Flux Distribution in the Oleaginous Microalga Chlorella protothecoides1[C][W][OA

    PubMed Central

    Xiong, Wei; Liu, Lixia; Wu, Chao; Yang, Chen; Wu, Qingyu

    2010-01-01

    The green alga Chlorella protothecoides has received considerable attention because it accumulates neutral triacylglycerols, commonly regarded as an ideal feedstock for biodiesel production. In order to gain a better understanding of its metabolism, tracer experiments with [U-13C]/[1-13C]glucose were performed with heterotrophic growth of C. protothecoides for identifying the metabolic network topology and estimating intracellular fluxes. Gas chromatography-mass spectrometry analysis tracked the labeling patterns of protein-bound amino acids, revealing a metabolic network consisting of the glycolysis, the pentose phosphate pathway, and the tricarboxylic acid cycle with inactive glyoxylate shunt. Evidence of phosphoenolpyruvate carboxylase, phosphoenolpyruvate carboxykinase, and malic enzyme activity was also obtained. It was demonstrated that the relative activity of the pentose phosphate pathway to glycolysis under nitrogen-limited environment increased, reflecting excess NADPH requirements for lipid biosynthesis. Although the growth rate and cellular oil content were significantly altered in response to nitrogen limitation, global flux distribution of C. protothecoides remained stable, exhibiting the rigidity of central carbon metabolism. In conclusion, quantitative knowledge on the metabolic flux distribution of oleaginous alga obtained in this study may be of value in designing strategies for metabolic engineering of desirable bioproducts. PMID:20720172

  13. Metabolism of doxylamine succinate in Fischer 344 rats. Part I: Distribution and excretion.

    PubMed

    Thompson, H C; Gosnell, A B; Holder, C L; Siitonen, P H; Rowland, K L; Cmarik, J L

    1986-01-01

    Experiments were conducted with male and female rats (12 per group) dosed by gavage with 2 or 20 mg (based on the free amine) doxylamine succinate containing about 10 microCi 14C-doxylamine succinate to determine distribution and excretion of the activity as a function of dose and sex with time. Urine and feces were collected at intervals up to 72 hr. Most of the dose (approximately equal to 70%) was eliminated in the first 24 hr after dosing and 95 to 100% of the dose was recovered during the 72-hr course of the experiments with both sexes and dose levels. Less than 1% of the total dose remained in the rats at the end of the test period. The urinary route of elimination was more predominant than the fecal route in both sexes given the 20-mg dose. The fecal route predominates in low-dose males whereas there is no significant difference between urinary and fecal routes of elimination in low-dose females. Preliminary characterization of urinary metabolite form using extraction techniques shows 99% of the metabolites to be in the polar conjugated form.

  14. Distribution of elements in individual blood cells in metabolic disorders at the cellular level

    NASA Astrophysics Data System (ADS)

    Johansson, Erland; Lindh, Ulf

    1985-08-01

    In comparison with controls neutrophil granulocytes from Rheumatoid arthritis (RA), Infantile Neuronal Ceroid Lipofuscinosis (INCL), Chronic Lymphatic Leukemia (L) and Aplastic Anemia (AA) displayed significant alterations in essential and non-essential elements which might be interpreted as fingerprints of these deseases. The neutrophils from RA patients displayed alterations in the concentrations of iron, calcium, strontium, manganese, zinc and copper. INCL displayed alterations in the concentrations of iron and copper but in the INCL disease the iron concentration was about 2 times higher than in RA. In leukemia, aluminium was observed but not in the controls (< 0.5 μg/ g). The zinc concentration was lowered in leukemia. Aplastic anemia displayed alterations in zirconium, arsenic, molybdenum, iron and zinc. The platelets from RA, INCL, L and AA patients also displayed alterations in the elemental profiles. The platelets from AA patients displayed a unique elemental distribution of arsenic, zirconium and molybdenum. The elemental profiles of the thrombocytes and neutrophils might be used as a complement in the diagnosis of the examined diseases and in therapy the elemental profile might be used to monitor drugs at the cellular level.

  15. A substantial fraction of phytoplankton-derived DON is resistant to degradation by a metabolically versatile, widely distributed marine bacterium

    PubMed Central

    Kimmance, Susan; McCormack, Paul

    2017-01-01

    The capacity of bacteria for degrading dissolved organic nitrogen (DON) and remineralising ammonium is of importance for marine ecosystems, as nitrogen availability frequently limits productivity. Here, we assess the capacity of a widely distributed and metabolically versatile marine bacterium to degrade phytoplankton-derived dissolved organic carbon (DOC) and nitrogen. To achieve this, we lysed exponentially growing diatoms and used the derived dissolved organic matter (DOM) to support an axenic culture of Alteromonas sp.. Bacterial biomass (as particulate carbon and nitrogen) was monitored for 70 days while growth dynamics (cell count), DOM (DOC, DON) and dissolved nutrient concentrations were monitored for up to 208 days. Bacterial biomass increased rapidly within the first 7 days prior to a period of growth/death cycles potentially linked to rapid nutrient recycling. We found that ≈75% of the initial DOC and ≈35% of the initial DON were consumed by bacteria within 40 and 4 days respectively, leaving a significant fraction of DOM resilient to degradation by this bacterial species. The different rates and extents to which DOC and DON were accessed resulted in changes in DOM stoichiometry and the iterative relationship between DOM quality and bacterial growth over time influenced bacterial cell C:N molar ratio. C:N values increased to 10 during the growth phase before decreasing to values of ≈5, indicating a change from relative N-limitation/C-sufficiency to relative C-limitation/N-sufficiency. Consequently, despite its reported metabolic versatility, we demonstrate that Alteromonas sp. was unable to access all phytoplankton derived DOM and that a bacterial community is likely to be required. By making the relatively simple assumption that an experimentally derived fraction of DOM remains resilient to bacterial degradation, these experimental results were corroborated by numerical simulations using a previously published model describing the interaction

  16. 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.

  17. The uptake, distribution, metabolism, and excretion of methyl tertiary-butyl ether inhaled alone and in combination with gasoline vapor.

    PubMed

    Benson, Janet M; Tibbetts, Brad M; Barr, Edward B

    2003-06-13

    The purpose of these studies was to evaluate the tissue uptake, distribution, metabolism, and excretion of methyl tertiary-butyl ether (MTBE) in rats and to determine the effects of coinhalation of the volatile fraction of unleaded gasoline on these parameters. Male F344 rats were exposed nose-only once for 4 h to 4, 40, or 400 ppm 14C-MTBE and to 20 and 200 ppm of the light fraction of unleaded gasoline (LFG) containing 4 and 40 ppm 14C-MTBE, respectively. To evaluate the effects of repeated inhalation of LFG on the fate of inhaled MTBE, rats were exposed for 7 consecutive days to 20 and 200 ppm LFG followed on d 8 by exposure to LFG containing 14C-MTBE. Three subgroups of rats were included for evaluation of respiratory parameters, rates and routes of excretion, and tissue distribution and elimination. MTBE and its chief metabolite, tertiary-butyl alcohol, were quantitated in blood and kidney (immediately after exposure), and the major urinary metabolites, 2-hydroxyisobutyric acid and 2-methyl-1,2- propanediol, were identified and quantified in urine. Inhalation of MTBE alone or as a component of LFG had no concentration-dependent effect on respiratory minute volume. The initial body burdens (IBBs) of MTBE equivalents achieved after 4 h of exposure to MTBE did not increase linearly with exposure concentration. MTBE equivalents rapidly distributed to all tissues examined, with the largest percentages distributed to liver. Between 40 and 400 ppm, there was a significant reduction in percentage of the IBB present in the major organs examined, both immediately and 72 h after exposure. At 400 ppm, the elimination rates of MTBE equivalents from tissues changed significantly. Furthermore, at 400 ppm there was a significant decrease in the elimination half-time of volatile organic compounds (VOCs) in breath and a significant increase in the percentage of the IBB of MTBE equivalents eliminated as VOCs in breath. LFG coexposure significantly decreased the percentage of the

  18. 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.

  19. 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.

  20. 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

    2016-08-12

    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.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    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.

  3. Metabolism and distribution of p,p'-DDT during flight of the white-crowned sparrow, Zonotrichia leucophrys.

    PubMed

    Scollon, Edward J; Carr, James A; Rintoul, David A; McMurry, Scott T; Cobb, George P

    2012-02-01

    This study evaluated the interactions of flight, fasting, and 1,1,1-trichloro-bis(4-chlorophenyl)ethane (p,p'-DDT) loading on residue metabolism and distribution in recently exposed white-crowned sparrows (Zonotrichia leucophrys). Female sparrows were dosed with 5 mg p,p'-DDT per kg body weight over 3 d. Following 1 d of recovery, sparrows were flown in a wind tunnel for up to 140 min, in 15-min blocks. Food was withheld from the start of the flight period until birds were euthanized. DDT, 1,1-dichloro-2,2-bis(4 chlorophenyl)ethane (DDD), and 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (DDE) were present in all tissues examined. 1-Chloro-2,2-bis(4-chlorophenyl)ethene (DDµ), 1,1-bis(4-chlorophenyl)ethane (p,p'-DDη), and 2,2-bis(4-chlorophenyl)ethanol (p,p'-DDOH) were not found. Fasting did not significantly affect the rate of residue increase over time in any of the tissues examined. When sparrows flew and fasted simultaneously, fasting seldom contributed to an increase in tissue residues. However, the length of time flown was significantly correlated with increasing toxicant concentrations in the brain, kidney, and liver, effectively demonstrating the potential for brief flights to enhance mobilization of DDT and its metabolites. Dose, flight, and fasting also increased residues in brain tissue. These contaminant redistributions may have important ramifications on the stresses experienced by migratory birds.

  4. 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

  5. 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

  6. Two isoforms of TALDO1 generated by alternative translational initiation show differential nucleocytoplasmic distribution to regulate the global metabolic network

    PubMed Central

    Moriyama, Tetsuji; Tanaka, Shu; Nakayama, Yasumune; Fukumoto, Masahiro; Tsujimura, Kenji; Yamada, Kohji; Bamba, Takeshi; Yoneda, Yoshihiro; Fukusaki, Eiichiro; Oka, Masahiro

    2016-01-01

    Transaldolase 1 (TALDO1) is a rate-limiting enzyme involved in the pentose phosphate pathway, which is traditionally thought to occur in the cytoplasm. In this study, we found that the gene TALDO1 has two translational initiation sites, generating two isoforms that differ by the presence of the first 10 N-terminal amino acids. Notably, the long and short isoforms were differentially localised to the cell nucleus and cytoplasm, respectively. Pull-down and in vitro transport assays showed that the long isoform, unlike the short one, binds to importin α and is actively transported into the nucleus in an importin α/β-dependent manner, demonstrating that the 10 N-terminal amino acids are essential for its nuclear localisation. Additionally, we found that these two isoforms can form homo- and/or hetero-dimers with different localisation dynamics. A metabolite analysis revealed that the subcellular localisation of TALDO1 is not crucial for its activity in the pentose phosphate pathway. However, the expression of these two isoforms differentially affected the levels of various metabolites, including components of the tricarboxylic acid cycle, nucleotides, and sugars. These results demonstrate that the nucleocytoplasmic distribution of TALDO1, modulated via alternative translational initiation and dimer formation, plays an important role in a wide range of metabolic networks. PMID:27703206

  7. 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.

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

    PubMed Central

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

    2015-01-01

    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

  9. 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.

  10. 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.

  11. Ambient salinity modifies the action of triiodothyronine in the air-breathing fish Anabas testudineus Bloch: effects on mitochondria-rich cell distribution, osmotic and metabolic regulations.

    PubMed

    Peter, M C Subhash; Leji, J; Peter, Valsa S

    2011-04-01

    The hydromineral and metabolic actions of thyroid hormone on osmotic acclimation in fish is less understood. We, therefore, studied the short-term action of triiodothyronine (T(3)), the potent thyroid hormone, on the distribution and the function of gill mitochondria-rich (MR) cells and on the whole body hydromineral and metabolic regulations of air-breathing fish (Anabas testudineus) adapted to either freshwater (FW) or acclimated to seawater (SA; 30 g L(-1)). As expected, 24 h T(3) injection (100 ng g(-1)) elevated (P<0.05) plasma T(3) but classically reduced (P<0.05) plasma T(4). The higher Na(+), K(+)-ATPase immunoreactivity and the varied distribution pattern of MR cells in the gills of T(3)-treated FW and SA fish, suggest an action of T(3) on gill MR cell migration, though the density of these cells remained unchanged after T(3) treatment. The ouabain-sensitive Na(+), K(+)-ATPase activity, a measure of hydromineral competence, showed increases (P<0.05) in the gills of both FW and SA fish after T(3) administration, but inhibited (P<0.05) in the kidney of the FW fish and not in the SA fish. Exogenous T(3) reduced glucose (P<0.05) and urea (P<0.05) in the plasma of FW fish, whereas these metabolites were elevated (P<0.05) in the SA fish, suggesting a modulatory effect of ambient salinity on the T(3)-driven metabolic actions. Our data identify gill MR cell as a target for T(3) action as it promotes the spatial distribution and the osmotic function of these cells in both fresh water and in seawater. The results besides confirming the metabolic and osmotic actions of T(3) in fish support the hypothesis that the differential actions of T(3) may be due to the direct influence of ambient salinity, a major environmental determinant that alters the osmotic and metabolic strategies of fish.

  12. Use of MRI and CT for fat imaging in children and youth: what have we learned about obesity, fat distribution and metabolic disease risk?

    PubMed

    Samara, A; Ventura, E E; Alfadda, A A; Goran, M I

    2012-08-01

    Childhood obesity is a matter of great concern for public health. Efforts have been made to understand its impact on health through advanced imaging techniques. An increasing number of studies focus on fat distribution and its associations with metabolic risk, in interaction with genetics, environment and ethnicity, in children. The present review is a qualitative synthesis of the existing literature on visceral and subcutaneous abdominal, intrahepatic and intramuscular fat. Our search revealed 80 original articles. Abdominal as well as ectopic fat depots are prevalent already in childhood and contribute to abnormal metabolic parameters, starting early in life. Visceral, hepatic and intramuscular fat seem to be interrelated but their patterns as well as their independent contribution on metabolic risk are not clear. Some ethnic-specific characteristics are also prevalent. These results encourage further research in childhood obesity by using imaging techniques such as magnetic resonance imaging and computed tomography. These imaging methods can provide a better understanding of fat distribution and its relationships with metabolic risk, compared to less detailed fat and obesity assessment. However, studies on bigger samples and with a prospective character are warranted.

  13. A review of obesity and body fat distribution and its relationship to cardio-metabolic risk in men and women of Chinese origin.

    PubMed

    Lear, Scott A; Lesser, Iris A

    2012-12-01

    Obesity is increasing in people of Chinese background whether in China or in other countries. The purpose of this review is to discuss the associations of obesity in men and women of Chinese background with cardio-metabolic risk with specific attention to body fat distribution. Evidence suggests that current BMI and WC targets may actually underestimate the cardio-metabolic risk in Chinese compared to European populations from which they were derived. Through a number of investigations, we and others have identified that Chinese men and women tend to have higher cardio-metabolic risk factors at a given body size than people of European background (from which guidelines are generally derived). Our additional investigations have indicated that Chinese men and women have greater amounts of VAT, but similar amounts of DSAT at a given body fat than Europeans and it may be the higher VAT in Chinese people that is, in part, responsible for the greater cardio-metabolic risk in the Chinese. Further investigation of this topic should prove fruitful in shedding light onto the determinants of body fat accumulation and distribution that may help to inform obesity prevention and treatment strategies.

  14. Distribution and Correlates of the Metabolic Syndrome in Adults Living in the San Juan Metropolitan Area of Puerto Rico

    PubMed Central

    Pérez, Cynthia M.; Ortiz, Ana P.; Guzmán, Manuel; Suárez, Erick

    2012-01-01

    Objectives This study evaluated correlates of the metabolic syndrome among adults living in Puerto Rico, a Hispanic subpopulation disproportionately affected by diabetes. Methods A probability cluster design was used to select a sample of households of the San Juan Metropolitan Area in Puerto Rico. A total of 858 persons aged 21–79 years completed a face-to-face interview, blood pressure and anthropometric measurements, blood sampling and spot urine. Logistic regression was employed to assess correlates of the metabolic syndrome. Results Of 368 (42.9%) of adults who met the criteria for metabolic syndrome, elevated fasting glucose (49.8%), abdominal obesity (48.6%), and reduced HDL cholesterol (45.8%) were the most prevalent diagnostic criteria. In a multivariable logistic model that simultaneously adjusted for sociodemographic characteristics and health behaviors, older age, high school educational attainment or less, no alcohol intake, and lack of moderate-to-vigorous physical activity remained significantly (p<0.05) associated to the metabolic syndrome. However, the associations for male gender, some college education, and current smoking ≥20 cigarettes/day had borderline significance. Further controlling for inflammatory markers slightly attenuated the strength of most of these associations but remained significantly (p<0.05) associated to the metabolic syndrome with only a few exceptions. Middle and upper tertiles of hs-CRP, fibrinogen, and PAI-1 and an elevated albumin-to-creatinine ratio were also associated (p<0.05) with the metabolic syndrome. Conclusions Enhancing public education regarding modifiable risk factors for the metabolic syndrome and providing optimal medical management of individual metabolic disturbances among those at risk through preventive lifestyle changes should be placed as a public health priority for Puerto Rico. PMID:23038883

  15. 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.

  16. Copper exposure interferes with the regulation of the uptake, distribution and metabolism of sulfate in Chinese cabbage.

    PubMed

    Shahbaz, Muhammad; Tseng, Mei Hwei; Stuiver, C Elisabeth E; Koralewska, Aleksandra; Posthumus, Freek S; Venema, Jan Henk; Parmar, Saroj; Schat, Henk; Hawkesford, Malcolm J; De Kok, Luit J

    2010-04-15

    Exposure of Chinese cabbage (Brassica pekinensis) to enhanced Cu(2+) concentrations (1-10 microM) resulted in leaf chlorosis, a loss of photosynthetic capacity and lower biomass production at > or = 5 microM. The decrease in pigment content was likely not the consequence of degradation, but due to hindered chloroplast development upon Cu exposure. The Cu content of the root increased with the Cu(2+) concentration (up to 40-fold), though only a minor proportion (4%) was transferred to the shoot. The nitrate uptake by the root was substantially reduced at > or = 5 microM Cu(2+). The nitrogen content of the root was affected little at lower Cu(2+) levels, whereas that in the shoot was decreased at > or = 5 microM Cu(2+). Cu affected the uptake, distribution and metabolism of sulfate in Chinese cabbage. The total sulfur content of the shoot was increased at > or = 2 microM Cu(2+), which could be attributed mainly to an increase in sulfate content. Moreover, there was a strong increase in water-soluble non-protein thiol content in the root and, to a lesser extent, in the shoot at > or = 1 microM, which could only partially be ascribed to a Cu-induced enhancement of the phytochelatin content. The nitrate uptake by the root was substantially reduced at > or = 5 microM Cu(2+), coinciding with a decrease in biomass production. However, the activity of the sulfate transporters in the root was slightly enhanced at 2 and 5 microM Cu(2+), accompanied by enhanced expression of the Group 1 high affinity transporter Sultr1;2, and the Group 4 transporters Sultr4;1 and Sultr4;2. In the shoot, there was an induction of expression of Sultr4;2 at 5 and 10 microM Cu(2+). The expression of APS reductase was affected little in the root and shoot up to 10 microM Cu(2+). The upregulation of the sulfate transporters may be due not only to greater sulfur demand at higher Cu levels, but also the consequence of interference by Cu with the signal transduction pathway regulating the expression

  17. 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.

  18. Adsorption of cellulase on cellulose: effect of physicochemical properties of cellulose on adsorption and rate of hydrolysis

    SciTech Connect

    Lee, S.B.; Shin, H.S.; Ryu, D.D.Y.

    1982-11-01

    In the cellulase-cellulose reaction system, the adsorption of cellulase on the solid cellulose substrate was found to be one of the important parameters that govern the enzymatic hydrolysis rate of cellulose. The adsorption of cellulase usually parallels the rate of hydrolysis of cellulose. The affinity for cellulase varies depending on the structural properties of cellulose. Adsorption parameters such as the half-saturation constant, the maximum adsorption constant, and the distribution coefficient for both the cellulase and cellulose have been experimentally determined for several substrates. These adsorption parameters vary with the source of cellulose and the pretreatment methods and are correlated with the crystallinity and the specific surface area of cellulose substrates. The changing pattern of adsorption profile of cellulase during the hydrolysis reaction has also been elucidated. For practical utilization of cellulosic materials, the cellulose structural properties and their effects on cellulase adsorption, and the rate of hydrolysis must be taken into consideration. (Refs. 24).

  19. 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.

  20. 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

  1. 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.

  2. Ionic Adsorption and Desorption of CNT Nanoropes

    PubMed Central

    Shang, Jun-Jun; Yang, Qing-Sheng; Yan, Xiao-Hui; He, Xiao-Qiao; Liew, Kim-Meow

    2016-01-01

    A nanorope is comprised of several carbon nanotubes (CNTs) with different chiralities. A molecular dynamic model is built to investigate the ionic adsorption and desorption of the CNT nanoropes. The charge distribution on the nanorope is obtained by using a modified gradient method based on classical electrostatic theory. The electrostatic interactions among charged carbon atoms are calculated by using the Coulomb law. It was found here that the charged nanorope can adsorb heavy metal ions, and the adsorption and desorption can be realized by controlling the strength of applied electric field. The distance between the ions and the nanorope as well as the amount of ions have an effect on the adsorption capacity of the nanorope. The desorption process takes less time than that of adsorption. The study indicates that the CNT nanorope can be used as a core element of devices for sewage treatment. PMID:28335306

  3. Assessment of metabolic flux distribution in the thermophilic hydrogen producer Caloramator celer as affected by external pH and hydrogen partial pressure

    PubMed Central

    2014-01-01

    Background Caloramator celer is a strict anaerobic, alkalitolerant, thermophilic bacterium capable of converting glucose to hydrogen (H2), carbon dioxide, acetate, ethanol and formate by a mixed acid fermentation. Depending on the growth conditions C. celer can produce H2 at high yields. For a biotechnological exploitation of this bacterium for H2 production it is crucial to understand the factors that regulate carbon and electron fluxes and therefore the final distribution of metabolites to channel the metabolic flux towards the desired product. Results Combining experimental results from batch fermentations with genome analysis, reconstruction of central carbon metabolism and metabolic flux analysis (MFA), this study shed light on glucose catabolism of the thermophilic alkalitolerant bacterium C. celer. Two innate factors pertaining to culture conditions have been identified to significantly affect the metabolic flux distribution: culture pH and partial pressures of H2 (PH2). Overall, at alkaline to neutral pH the rate of biomass synthesis was maximized, whereas at acidic pH the lower growth rate and the less efficient biomass formation are accompanied with more efficient energy recovery from the substrate indicating high cell maintenance possibly to sustain intracellular pH homeostasis. Higher H2 yields were associated with fermentation at acidic pH as a consequence of the lower synthesis of other reduced by-products such as formate and ethanol. In contrast, PH2 did not affect the growth of C. celer on glucose. At high PH2 the cellular redox state was balanced by rerouting the flow of carbon and electrons to ethanol and formate production allowing unaltered glycolytic flux and growth rate, but resulting in a decreased H2 synthesis. Conclusion C. celer possesses a flexible fermentative metabolism that allows redistribution of fluxes at key metabolic nodes to simultaneously control redox state and efficiently harvest energy from substrate even under unfavorable

  4. Distributions.

    ERIC Educational Resources Information Center

    Bowers, Wayne A.

    This monograph was written for the Conference of the New Instructional Materials in Physics, held at the University of Washington in summer, 1965. It is intended for students who have had an introductory college physics course. It seeks to provide an introduction to the idea of distributions in general, and to some aspects of the subject in…

  5. 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.

  6. In Absence of the Cellular Prion Protein, Alterations in Copper Metabolism and Copper-Dependent Oxidase Activity Affect Iron Distribution.

    PubMed

    Gasperini, Lisa; Meneghetti, Elisa; Legname, Giuseppe; Benetti, Federico

    2016-01-01

    Essential elements as copper and iron modulate a wide range of physiological functions. Their metabolism is strictly regulated by cellular pathways, since dysregulation of metal homeostasis is responsible for many detrimental effects. Neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease and prion diseases are characterized by alterations of metal ions. These neurodegenerative maladies involve proteins that bind metals and mediate their metabolism through not well-defined mechanisms. Prion protein, for instance, interacts with divalent cations via multiple metal-binding sites and it modulates several metal-dependent physiological functions, such as S-nitrosylation of NMDA receptors. In this work we focused on the effect of prion protein absence on copper and iron metabolism during development and adulthood. In particular, we investigated copper and iron functional values in serum and several organs such as liver, spleen, total brain and isolated hippocampus. Our results show that iron content is diminished in prion protein-null mouse serum, while it accumulates in liver and spleen. Our data suggest that these alterations can be due to impairments in copper-dependent cerulopalsmin activity which is known to affect iron mobilization. In prion protein-null mouse total brain and hippocampus, metal ion content shows a fluctuating trend, suggesting the presence of homeostatic compensatory mechanisms. However, copper and iron functional values are likely altered also in these two organs, as indicated by the modulation of metal-binding protein expression levels. Altogether, these results reveal that the absence of the cellular prion protein impairs copper metabolism and copper-dependent oxidase activity, with ensuing alteration of iron mobilization from cellular storage compartments.

  7. In Absence of the Cellular Prion Protein, Alterations in Copper Metabolism and Copper-Dependent Oxidase Activity Affect Iron Distribution

    PubMed Central

    Gasperini, Lisa; Meneghetti, Elisa; Legname, Giuseppe; Benetti, Federico

    2016-01-01

    Essential elements as copper and iron modulate a wide range of physiological functions. Their metabolism is strictly regulated by cellular pathways, since dysregulation of metal homeostasis is responsible for many detrimental effects. Neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease and prion diseases are characterized by alterations of metal ions. These neurodegenerative maladies involve proteins that bind metals and mediate their metabolism through not well-defined mechanisms. Prion protein, for instance, interacts with divalent cations via multiple metal-binding sites and it modulates several metal-dependent physiological functions, such as S-nitrosylation of NMDA receptors. In this work we focused on the effect of prion protein absence on copper and iron metabolism during development and adulthood. In particular, we investigated copper and iron functional values in serum and several organs such as liver, spleen, total brain and isolated hippocampus. Our results show that iron content is diminished in prion protein-null mouse serum, while it accumulates in liver and spleen. Our data suggest that these alterations can be due to impairments in copper-dependent cerulopalsmin activity which is known to affect iron mobilization. In prion protein-null mouse total brain and hippocampus, metal ion content shows a fluctuating trend, suggesting the presence of homeostatic compensatory mechanisms. However, copper and iron functional values are likely altered also in these two organs, as indicated by the modulation of metal-binding protein expression levels. Altogether, these results reveal that the absence of the cellular prion protein impairs copper metabolism and copper-dependent oxidase activity, with ensuing alteration of iron mobilization from cellular storage compartments. PMID:27729845

  8. 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…

  9. Bile salt adsorption ability of dietary fiber from named varieties of carrot at different developmental ages.

    PubMed

    Robertson, J A; Eastwood, M A; Yeoman, M M

    1980-06-01

    The adsorption of bile salts to fiber has been measured using fiber prepared from different varieties of carrot at different developmental ages. We investigated the carrot varieties Altrinchan and Chantenay and used the bile salts deoxycholate and glycocholate. The method used to measure adsorption distinguished between true adsorption and apparent adsorption due to bile salts trapped within the interstices of the fiber matrix. Adsorption ability was influenced by the developmental age of the carrot but not by variety. Adsorption ability was at a maximum when the carrot fresh weight was at a maximum. The adsorption ability measured was true adsorption and was not dependent on the water holding capacity of the fiber. Deoxycholate was better adsorbed than glycocholate and the results suggest that the developmental age of a fiber source could be important when formulating diets designed to influence bile salt metabolism.

  10. Optimizing the distribution of resources between enzymes of carbon metabolism can dramatically increase photosynthetic rate: a numerical simulation using an evolutionary algorithm.

    PubMed

    Zhu, Xin-Guang; de Sturler, Eric; Long, Stephen P

    2007-10-01

    The distribution of resources between enzymes of photosynthetic carbon metabolism might be assumed to have been optimized by natural selection. However, natural selection for survival and fecundity does not necessarily select for maximal photosynthetic productivity. Further, the concentration of a key substrate, atmospheric CO(2), has changed more over the past 100 years than the past 25 million years, with the likelihood that natural selection has had inadequate time to reoptimize resource partitioning for this change. Could photosynthetic rate be increased by altered partitioning of resources among the enzymes of carbon metabolism? This question is addressed using an "evolutionary" algorithm to progressively search for multiple alterations in partitioning that increase photosynthetic rate. To do this, we extended existing metabolic models of C(3) photosynthesis by including the photorespiratory pathway (PCOP) and metabolism to starch and sucrose to develop a complete dynamic model of photosynthetic carbon metabolism. The model consists of linked differential equations, each representing the change of concentration of one metabolite. Initial concentrations of metabolites and maximal activities of enzymes were extracted from the literature. The dynamics of CO(2) fixation and metabolite concentrations were realistically simulated by numerical integration, such that the model could mimic well-established physiological phenomena. For example, a realistic steady-state rate of CO(2) uptake was attained and then reattained after perturbing O(2) concentration. Using an evolutionary algorithm, partitioning of a fixed total amount of protein-nitrogen between enzymes was allowed to vary. The individual with the higher light-saturated photosynthetic rate was selected and used to seed the next generation. After 1,500 generations, photosynthesis was increased substantially. This suggests that the "typical" partitioning in C(3) leaves might be suboptimal for maximizing the light

  11. 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

  12. 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...

  13. THE ACQUISITION AND APPLICATION OF ABSORPTION, DISTRIBUTION, METABOLISM, AND EXCRETION (ADME) DATA IN AGRICULTURAL CHEMICAL SAFETY ASSESSMENTS

    EPA Science Inventory

    A multi-sector international group of government, academic, and industry scientists has developed a proposal for an improved testing scheme for assessing the safety of crop protection chemicals. Incorporation of pharmacokinetic studies describing the absorption, distribution, me...

  14. Perturbed equilibria of myosin binding in airway smooth muscle: bond-length distributions, mechanics, and ATP metabolism.

    PubMed Central

    Mijailovich, S M; Butler, J P; Fredberg, J J

    2000-01-01

    We carried out a detailed mathematical analysis of the effects of length fluctuations on the dynamically evolving cross-bridge distributions, simulating those that occur in airway smooth muscle during breathing. We used the latch regulation scheme of Hai and Murphy (Am. J. Physiol. Cell Physiol. 255:C86-C94, 1988) integrated with Huxley's sliding filament theory of muscle contraction. This analysis showed that imposed length fluctuations decrease the mean number of attached bridges, depress muscle force and stiffness, and increase force-length hysteresis. At frequencies >0.1 Hz, the bond-length distribution of slowly cycling latch bridges changed little over the stretch cycle and contributed almost elastically to muscle force, but the rapidly cycling cross-bridge distribution changed substantially and dominated the hysteresis. By contrast, at frequencies <0.033 Hz this behavior was reversed: the rapid cycling cross-bridge distribution changed little, effectively functioning as a constant force generator, while the latch bridge bond distribution changed substantially and dominated the stiffness and hysteresis. The analysis showed the dissociation of force/length hysteresis and cross-bridge cycling rates when strain amplitude exceeds 3%; that is, there is only a weak coupling between net external mechanical work and the ATP consumption required for cycling cross-bridges during the oscillatory steady state. Although these results are specific to airway smooth muscle, the approach generalizes to other smooth muscles subjected to cyclic length fluctuations. PMID:11053139

  15. 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.

  16. Hybrid adsorptive membrane reactor

    SciTech Connect

    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.

  17. Studies of nontarget-mediated distribution of human full-length IgG1 antibody and its FAb fragment in cardiovascular and metabolic-related tissues.

    PubMed

    Davidsson, Pia; Söderling, Ann-Sofi; Svensson, Lena; Ahnmark, Andrea; Flodin, Christine; Wanag, Ewa; Screpanti-Sundqvist, Valentina; Gennemark, Peter

    2015-05-01

    Tissue distribution and pharmacokinetics (PK) of full-length nontargeted antibody and its antigen-binding fragment (FAb) were evaluated for a range of tissues primarily of interest for cardiovascular and metabolic diseases. Mice were intravenously injected with a dose of 10 mg/kg of either human IgG1or its FAb fragment; perfused tissues were collected at a range of time points over 3 weeks for the human IgG1 antibody and 1 week for the human FAb antibody. Tissues were homogenized and antibody concentrations were measured by specific immunoassays on the Gyros system. Exposure in terms of maximum concentration (Cmax ) and area under the curve was assessed for all nine tissues. Tissue exposure of full-length antibody relative to plasma exposure was found to be between 1% and 10%, except for brain (0.2%). Relative concentrations of FAb antibody were the same, except for kidney tissue, where the antibody concentration was found to be ten times higher than in plasma. However, the absolute tissue uptake of full-length IgG was significantly higher than the absolute tissue uptake of the FAb antibody. This study provides a reference PK state for full-length whole and FAb antibodies in tissues related to cardiovascular and metabolic diseases that do not include antigen or antibody binding.

  18. 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.

  19. 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.

  20. Conjugation of metronidazole with dextran: a potential pharmaceutical strategy to control colonic distribution of the anti-amebic drug susceptible to metabolism by colonic microbes

    PubMed Central

    Kim, Wooseong; Yang, Yejin; Kim, Dohoon; Jeong, Seongkeun; Yoo, Jin-Wook; Yoon, Jeong-Hyun; Jung, Yunjin

    2017-01-01

    Metronidazole (MTDZ), the drug of choice for the treatment of protozoal infections such as luminal amebiasis, is highly susceptible to colonic metabolism, which may hinder its conversion from a colon-specific prodrug to an effective anti-amebic agent targeting the entire large intestine. Thus, in an attempt to control the colonic distribution of the drug, a polymeric colon-specific prodrug, MTDZ conjugated to dextran via a succinate linker (Dex-SA-MTDZ), was designed. Upon treatment with dextranase for 8 h, the degree of Dex-SA-MTDZ depolymerization (%) with a degree of substitution (mg of MTDZ bound in 100 mg of Dex-SA-MTDZ) of 7, 17, and 30 was 72, 38, and 8, respectively, while that of dextran was 85. Depolymerization of Dex-SA-MTDZ was found to be necessary for the release of MTDZ, because dextranase pretreatment ensures that de-esterification occurs between MTDZ and the dextran backbone. In parallel, Dex-SA-MTDZ with a degree of substitution of 17 was found not to release MTDZ upon incubation with the contents of the small intestine and stomach of rats, but it released MTDZ when incubated with rat cecal contents (including microbial dextranases). Moreover, Dex-SA-MTDZ exhibited prolonged release of MTDZ, which contrasts with drug release by small molecular colon-specific prodrugs, MTDZ sulfate and N-nicotinoyl-2-{2-(2-methyl-5-nitroimidazol-1-yl)ethyloxy}-d,l-glycine. These prodrugs were eliminated very rapidly, and no MTDZ was detected in the cecal contents. Consistent with these in vitro results, we found that oral gavage of Dex-SA-MTDZ delivered MTDZ (as MTDZ conjugated to [depolymerized] dextran) to the distal colon. However, upon oral gavage of the small molecular prodrugs, no prodrugs were detected in the distal colon. Collectively, these data suggest that dextran conjugation is a potential pharmaceutical strategy to control the colonic distribution of drugs susceptible to colonic microbial metabolism. PMID:28243064

  1. 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.

  2. Adsorption on Highly Ordered Porous Alumina

    NASA Astrophysics Data System (ADS)

    Mistura, Giampaolo; Bruschi, Lorenzo; Lee, Woo

    2016-10-01

    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.

  3. Adsorption characteristics of brilliant green dye on kaolin.

    PubMed

    Nandi, B K; Goswami, A; Purkait, M K

    2009-01-15

    Experimental investigations were carried out to adsorb toxic brilliant green dye from aqueous medium using kaolin as an adsorbent. Characterization of kaolin is done by measuring: (i) particle size distribution using particle size analyzer, (ii) BET surface area using BET surface analyzer, and (iii) structural analysis using X-ray diffractometer. The effects of initial dye concentration, contact time, kaolin dose, stirring speed, pH and temperature were studied for the adsorption of brilliant green in batch mode. Adsorption experiments indicate that the extent of adsorption is strongly dependent on pH of solution. Free energy of adsorption (DeltaG0), enthalpy (DeltaH0) and entropy (DeltaS0) changes are calculated to know the nature of adsorption. The calculated values of DeltaG0 at 299K and 323K indicate that the adsorption process is spontaneous. The estimated values of DeltaH0 and DeltaS0 both show the negative sign, which indicate that the adsorption process is exothermic and the dye molecules are organized on the kaolin surface in less randomly fashion than in solution. The adsorption kinetic has been described by first-order, pseudo-second-order and intra-particle-diffusion models. It was observed that the rate of dye adsorption follows pseudo-second-order model for the dye concentration range studied in the present case. Standard adsorption isotherms were used to fit the experimental equilibrium data. It was found that the adsorption of brilliant green on kaolin follows the Langmuir adsorption isotherm.

  4. 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].

  5. Pharmacokinetics, Distribution, Metabolism, and Excretion of Omadacycline following a Single Intravenous or Oral Dose of 14C-Omadacycline in Rats

    PubMed Central

    Lin, Wen; Flarakos, Jimmy; Du, Yancy; Hu, Wenyu; He, Handan; Mangold, James; Tanaka, S. Ken

    2016-01-01

    ABSTRACT The absorption, distribution, metabolism, and excretion (ADME) of omadacycline, a first-in-class aminomethylcycline antibiotic with a broad spectrum of activity against Gram-positive, Gram-negative, anaerobic, and atypical bacteria, were evaluated in rats. Tissue distribution was investigated by quantitative whole-body autoradiography in male Long-Evans Hooded (LEH) rats. Following an intravenous (i.v.) dose of 5 mg/kg of body weight, radioactivity widely and rapidly distributed into most tissues. The highest tissue-to-blood concentration ratios (t/b) were observed in bone mineral, thyroid gland, and Harderian gland at 24 h post-i.v. dose. There was no evidence of stable accumulation in uveal tract tissue, suggesting the absence of a stable binding interaction with melanin. Following a 90 mg/kg oral dose in LEH rats, the highest t/b were observed in bone mineral, Harderian gland, liver, spleen, and salivary gland. The plasma protein binding levels were 26% in the rat and 15% to 21% in other species. Omadacycline plasma clearance was 1.2 liters/h/kg, and its half-life was 4.6 h; the steady-state volume of distribution (Vss) was 6.89 liters/kg. Major circulating components in plasma were intact omadacycline and its epimer. Consistent with observations in human, approximately 80% of the dose was excreted into the feces as unchanged omadacycline after i.v. administration. Fecal excretion was primarily the result of biliary excretion (∼40%) and direct gastrointestinal secretion (∼30%). However, urinary excretion (∼30%) was equally prominent after i.v. dosing. PMID:27821446

  6. Adsorption of star polymers

    NASA Astrophysics Data System (ADS)

    Halperin, A.; Joanny, J. F.

    1991-06-01

    The adsorption of star polymers on a flat solid surface is analyzed by means of scalling arguments based on the Daoud-Cotton blob model. For the adsorption of a single star, consisting of f arms comprising each N monomers, we distinguish three regimes determined by the adsorption energy of a monomer at the surface, δ kT. 1) Strong adsorption characterized by the full adsorption of all arms occurs for δ > (f/N)^{3/5}. 2) A “Sombrero” like structure comprising f_ads fully adsorbed arms and f{-}f_ads free arms is obtained for (f/N)^{3/5}> δ > f^{9/20}/N^{3/5}. 3) Weakly adsorbed stars retain, essentially, the structure of a free star. This regime occurs for δ < f^{9/20}/N^{3/5}. The weakly adsorbed structure may also exist as a metastable state if δ > f^{9/5}/N^{3/5}. Nous étudions l'adsorption de polymères en étoile sur une surface solide en utilisant une approche de lois d'échelles basée sur le modèle de blobs de Daoud et Cotton. Pour une étoile formée de f bras contenant chacun N monomères, nous distinguons trois régimes suivant la valeur de l'énergie d'adsorption d'un monomère sur la surface δ kT. 1) L'adsorption forte caractérisée par une adsorption complète de tous les bras se produit lorsque δ > (f/N)^{3/5}. 2) Une structure en “sombrero” avec f_ads bras adsorbés et f{-}f_ads bras libres est obtenue si f^{9/20}/N^{3/5}δ < (f/N)^{3/5}. 3) Les étoiles faiblement adsorbées gardent une structure très similaire à celle des étoiles libres en solution. Ce régime existe si δ < f^{9/20}/N^{3/5}. La structure correspondant aux étoiles faiblement adsorbées peut aussi exister comme un état métastable si δ > f^{9/5}/N^{3/5}.

  7. 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.

  8. 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.

  9. Accumulation and distribution of trivalent chromium and effects on hybrid willow (Salix matsudana Koidz x alba L.) metabolism.

    PubMed

    Yu, X-Z; Gu, J-D

    2007-05-01

    The metabolic response of plants to exogenous supply and bioaccumulation of trivalent chromium (Cr(3+) ) was investigated. Pre-rooted young hybrid willows (Salix matsudana Koidz x alba L.) were exposed to hydroponic solution spiked with CrCl(3) at 24.0 degrees C +/- 1 degrees C for 192 hours. Various physiologic parameters of the plants were monitored to determine toxicity from Cr exposure. The transpiration rate of willows exposed to 2.5 mg Cr/L was 49% higher than that of the untreated control plants, but it was decreased by 17% when exposed to 30.0 mg Cr/L. Significant decrease (> or =20%) of soluble protein in young leaves of willows was detected in the treatment group with > or =7.5 mg Cr/L. The measured chlorophyll contents in leaves of treated plants varied with the dose of Cr, but a linear correlation could not be established. The contents of chlorophyll in leaves of willows exposed to > or =7.5 mg Cr/L were higher than that of the untreated plants but lower at 30.0 mg Cr/L. Superoxide dismutase activity (SOD) in leaves between the treated and untreated willows did not show any significant difference, but activities of both catalase (CAT) and peroxidase (POD) in leaf cells of all treated plants were higher than those in the untreated willows. The correlation between the concentration of Cr and CAT activity in leaf cells was the highest of all toxicity assays (R ( 2 ) = 0.9096), indicating that CAT activity was most sensitive to the change in Cr(3+) doses compared with the other selected parameters. Results from the Cr uptake study showed that significant removal of Cr from hydroponic solution was observed in the presence of hybrid willows without showing detectable phytotoxicity, even at high does of Cr. More than 90% of the applied Cr(3+) was removed from the aqueous solution by willows at concentrations up to 7.5 mg Cr/L. Approximately 70% of the initial Cr was recovered in the plant materials. At the low-Cr(3+) treatment (2.5 mg Cr/L), Cr accumulation by

  10. Yield and quality responses, plant metabolism and metal distribution pattern in aromatic rice under lead (Pb) toxicity.

    PubMed

    Ashraf, Umair; Tang, Xiangru

    2017-02-24

    Present study was planned to assess the yield and quality responses, plant physio-biochemical characters and Pb distribution pattern in two aromatic rice cultivars viz., Guixiangzhan (GXZ) and Nongxiang-18 (NX-18) under four different Pb-levels viz., control (0), low (400), medium (800) and high (1200) mg kg(-1)of soil. Results revealed that Pb toxicity increased H2O2, lipid peroxidation and electrolyte leakage while inhibited photosynthetic pigments production, but such increment was higher in NX-18 than GXZ. Furthermore, Pb toxicity variably affected protein, proline and soluble sugars and the activities of enzymatic antioxidants viz., superoxide dismutase (SOD), peroxidases (POD), catalases (CAT) and ascorbate peroxidases (APX) and non-enzymatic anti-oxidants viz., reduced glutathione (GSH) and oxidized glutathione (GSSG) in both rice cultivars. The reductions in osmolyte accumulation and antioxidant activities were more severe in NX-18 than GXZ. Pb toxicity severely reduced yield and quality related attributes and plant biomass accumulation; however the reductions were more apparent NX-18 than GXZ. Furthermore, NX-18 accumulated less Pb proportions in roots (∼84%), and transferred more towards shoot, leaves, ears (at panicle heading (PH)) and grains (at maturity (MAT)) than GXZ (∼91% root Pb proportions). Hence, the ability of GXZ to retain higher Pb contents in roots and less towards upper plant parts, higher osmolyte accumulation and antioxidant activities and less yield reduction as compare to NX-18 might be an adaptive response of GXZ under Pb toxicity.

  11. 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

  12. Characterization of the microbial community composition and the distribution of Fe-metabolizing bacteria in a creek contaminated by acid mine drainage.

    PubMed

    Sun, Weimin; Xiao, Enzong; Krumins, Valdis; Dong, Yiran; Xiao, Tangfu; Ning, Zengping; Chen, Haiyan; Xiao, Qingxiang

    2016-10-01

    A small watershed heavily contaminated by long-term acid mine drainage (AMD) from an upstream abandoned coal mine was selected to study the microbial community developed in such extreme system. The watershed consists of AMD-contaminated creek, adjacent contaminated soils, and a small cascade aeration unit constructed downstream, which provide an excellent contaminated site to study the microbial response in diverse extreme AMD-polluted environments. The results showed that the innate microbial communities were dominated by acidophilic bacteria, especially acidophilic Fe-metabolizing bacteria, suggesting that Fe and pH are the primary environmental factors in governing the indigenous microbial communities. The distribution of Fe-metabolizing bacteria showed distinct site-specific patterns. A pronounced shift from diverse communities in the upstream to Proteobacteria-dominated communities in the downstream was observed in the ecosystem. This location-specific trend was more apparent at genus level. In the upstream samples (sampling sites just below the coal mining adit), a number of Fe(II)-oxidizing bacteria such as Alicyclobacillus spp., Metallibacterium spp., and Acidithrix spp. were dominant, while Halomonas spp. were the major Fe(II)-oxidizing bacteria observed in downstream samples. Additionally, Acidiphilium, an Fe(III)-reducing bacterium, was enriched in the upstream samples, while Shewanella spp. were the dominant Fe(III)-reducing bacteria in downstream samples. Further investigation using linear discriminant analysis (LDA) effect size (LEfSe), principal coordinate analysis (PCoA), and unweighted pair group method with arithmetic mean (UPGMA) clustering confirmed the difference of microbial communities between upstream and downstream samples. Canonical correspondence analysis (CCA) and Spearman's rank correlation indicate that total organic carbon (TOC) content is the primary environmental parameter in structuring the indigenous microbial communities

  13. 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

  14. Analysis of Global and Absorption, Distribution, Metabolism, and Elimination Gene Expression in the Progressive Stages of Human Nonalcoholic Fatty Liver DiseaseS⃞

    PubMed Central

    Lake, April D.; Novak, Petr; Fisher, Craig D.; Jackson, Jonathan P.; Hardwick, Rhiannon N.; Billheimer, D. Dean; Klimecki, Walter T.

    2011-01-01

    Nonalcoholic fatty liver disease (NAFLD) is characterized by a series of pathological changes that range from simple fatty liver to nonalcoholic steatohepatitis (NASH). The objective of this study is to describe changes in global gene expression associated with the progression of human NAFLD. This study is focused on the expression levels of genes responsible for the absorption, distribution, metabolism, and elimination (ADME) of drugs. Differential gene expression between three clinically defined pathological groups—normal, steatosis, and NASH—was analyzed. Genome-wide mRNA levels in samples of human liver tissue were assayed with Affymetrix GeneChip Human 1.0ST arrays. A total of 11,633 genes exhibited altered expression out of 33,252 genes at a 5% false discovery rate. Most gene expression changes occurred in the progression from steatosis to NASH. Principal component analysis revealed that hepatic disease status was the major determinant of differential ADME gene expression rather than age or sex of sample donors. Among the 515 drug transporters and 258 drug-metabolizing enzymes (DMEs) examined, uptake transporters but not efflux transporters or DMEs were significantly over-represented in the number of genes down-regulated. These results suggest that uptake transporter genes are coordinately targeted for down-regulation at the global level during the pathological development of NASH and that these patients may have decreased drug uptake capacity. This coordinated regulation of uptake transporter genes is indicative of a hepatoprotective mechanism acting to prevent accumulation of toxic intermediates in disease-compromised hepatocytes. PMID:21737566

  15. L-carnitine and cancer cachexia. I. L-carnitine distribution and metabolic disorders in cancer cachexia.

    PubMed

    Szefel, Jarosław; Kruszewski, Wiesław Janusz; Ciesielski, Maciej; Szajewski, Mariusz; Kawecki, Krzysztof; Aleksandrowicz-Wrona, Ewa; Jankun, Jerzy; Lysiak-Szydłowska, Wiesława

    2012-07-01

    Cancer cachexia (CC), a progressive loss of body mass, is associated with decreased energy production. Abnormally low levels of L-carnitine (LC) in skeletal muscle means that mitochondrial β-oxidation of long-chain fatty acids (LCFA) does not occur efficiently in patients with CC. We assessed the influence of CC on LC distribution and the effects of parenteral lipid emulsions on plasma LC levels and urinary excretion. Fifty patients with CC were randomly assigned to total parenteral nutrition (TPN) with long-chain triglycerides (LCTs), or LCTs plus medium-chain triglycerides (MCTs) as 50/50. Patients were further separated into those with body-mass index (BMI) ≤ 19 kg/m(2) and BMI >19 kg/m(2). Plasma concentrations of total LC (TC) and free LC (FC) and their urinary excretion were measured, along with skeletal muscle LC levels. On average, plasma FC and TC were higher than reference values in all patients. Patients with BMI ≤ 19 kg/m(2) had lower plasma FC and TC than those with BMI >19 kg/m(2). Skeletal muscle FC in the BMI ≤ 19 kg/m(2) group was lower than reference value, but within the normal range in others. LC and FC urinary excretion was higher than reference values. Plasma LC and its urinary excretion were higher in patients administered pure LCTs relative to those given MCTs/LCTs. A decrease in skeletal muscle LC in cancer patients with CC (BMI ≤ 19 kg/m(2)) correlates with an increase in its plasma levels and increased renal excretion. A diet of MCTs/LCTs reduces LC release from muscle to plasma and urine more effectively than LCTs.

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

    PubMed

    Hølmer, G; Rønneberg, 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 [14-14C]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 [14C]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 [14C]18:1 incorporation in both TG and PL, and increasing from 15 to 60 min of perfusion. The amount of [14C]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 [14-14C]erucic acid, and only small amounts of [14C]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.

  17. Effects of oral administration of berberine on distribution and metabolism of 2-aminofluorene in Sprague-Dawley rats.

    PubMed

    Lin, Chin-Chung; Kao, Shung-Te; Ho, Chin-Chin; Ho, Heng-Chien; Hsia, Te-Chun; Yang, Mei-Due; Yeh, Chin-Chung; Liu, Po-Erh; Chung, Jing-Gung

    2007-01-01

    The effects of berberine on the in vivo N-acetylation and metabolism of 2-aminofluorene (2-AF) in bladder, blood, colon, kidney, liver, feces and urine samples and brain tissues (cerebrum, cerebellum and pineal gland) of male Sprague-Dawley rats were investigated. Major metabolites, such as 1-OH-2-AAF, 3-OH-2-AAF, 8-OH-2-AAF and 9-OH-2-AAF were found in bladder tissues, 1-OH-2-AAF, 5-OH-2-AAF and 8-OH-2-AAF were found in blood samples, 1-OH-2-AAF, 3-OH-2-AAF, 5-OH-2-AAF, 8-OH-2-AAF and 9-OH-2-AAF were found in colon tissues, 1-OH-2-AAF, 3-OH-2-AAF and 9-OH-2-AAF were found in kidney tissues, 1-OH-2-AAF, 3-OH-2-AAF and 8-OH-2-AAF were found in liver tissues, 1-OH-2-AAF, 3-OH-2-AAF, 5-OH-2-AAF, 7-OH-2-AAF, 8-OH-2-AA and 9-OH-2-AAF were found in feces samples and 1-OH-2-AAF, 3-OH-2-AAF, 5-OH-2-AAF, 7-OH-2-AAF, 8-OH-2-AA and 9-OH-2-AAF were also found in urine samples, 1-OH-2-AAF, 3-OH-2-AAF and 8-OH-2-AAF were found in cerebrum tissues, 1-OH-2-AAF, 3-OH-2-AAF and 7-OH-2-AAF were found in cerebellum tissues. In the control group, however, only 2-AF and 2-AAF were found in pineal gland after rats had been orally treated with 2-AF (50 mg/kg) for 24 h. Pre-treatment of male rats with berberine (40 mg/kg) 24 h prior to the administration of 2-AF (50 mg/kg), as well as the co-administration of berberine and 2-AF led to a decrease in the amounts of 3-OH-2-AAF and an increase in the amounts of 8-OH-2-AAF in bladder tissues. In blood samples, there were significant decreases of 2-AF, 2-AAF, 1-OH-2-AAF and 8-OH-2-AAF, after rats were pre-treated with berberine for 24 h before the addition of 2-AF. However, co-administration of berberine and 2-AF led to an increase in the amounts of 5-OH-2-AAF. In colon tissues, there were significant decreases of 2-AF, 2-AAF, 1-OH-2-AAF and 8-OH-2-AAF in colon samples after rats were treated with berberine for 24 h before the addition of 2-AF. 2-AF, 1-OH-2-AAF, 3-OH-2-AAF and 9-OH-2-AAF levels were significantly different between control and

  18. Distribution of CYP2D6 and CYP2C19 Polymorphisms Associated with Poor Metabolizer Phenotype in Five Amerindian Groups and Western Mestizos from Mexico

    PubMed Central

    Salazar-Flores, Joel; Torres-Reyes, Luis A.; Martínez-Cortés, Gabriela; Rubi-Castellanos, Rodrigo; Sosa-Macías, Martha; Muñoz-Valle, José F.; González-González, César; Ramírez, Angélica; Román, Raquel; Méndez, José L.; Barrera, Andrés; Torres, Alfredo; Medina, Rafael

    2012-01-01

    Background: The distribution of polymorphisms in the CYP2D6 and CYP2C19 genes allows inferring the potential risk for specific adverse drug reactions and lack of therapeutic effects in humans. This variability shows differences among human populations. The aim of this study was to analyze single-nucleotide polymorphisms related to a poor metabolizer (PM) phenotype in nonpreviously studied Amerindian groups and Mestizos (general admixed population) from Mexico. Methods: We detected by SNaPshot® different polymorphisms located in CYP2D6 (*3, *4, *6, *7, and *8) and CYP2C19 (*2, *3, *4 and *5) in western Mestizos (n=145) and five Amerindian groups from Mexico: Tarahumaras from the North (n=88); Purépechas from the Center (n=101); and Tojolabales (n=68), Tzotziles (n=88), and Tzeltales (n=20) from the Southeast. Genotypes were observed by capillary electrophoresis. The genetic relationships among these populations were estimated based on these genes. Results and Discussion: The wild-type allele (*1) of both genes was predominant in the Mexican populations studied. The most widely observed alleles were CYP2C19*2 (range, 0%–31%) and CYP2D6*4 (range, 1.2%–7.3%), whereas CYP2D6*3 was exclusively detected in Mestizos. Conversely, CYP2C19*4 and *5, as well as CYP2D6*3, *6, *7, and *8, were not observed in the majority of the Mexican populations. The Tarahumaras presented a high frequency of the allele CYP2C19*2 (31%) and of homozygotes *2/*2 (10.7%), which represent a high frequency of potentially PM phenotypes in this Amerindian group. The genetic distances showed high differentiation of Tarahumaras (principally for CYP2C19 gene). In general, a relative proximity was observed between most of the Amerindian, Mexican-Mestizo, and Latin-American populations. Conclusion: In general, the wild-type allele (*1) predominates in Mexican populations, outlining a relatively homogeneous distribution for CYP2C19 and CYP2D6. The exception is the Tarahumara group that displays a

  19. 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)

  20. SEPARATION BY ADSORPTION

    DOEpatents

    Lowe, C.S.

    1959-06-16

    Separation of Pu from fission products by adsorption on hydrous aluminum silicate is described. The Pu in a HNO/sub 3/ solution is oxidized to the hexavalent state and contacted with the silicate which adsorbs fission products. (T.R.H.)

  1. 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

  2. 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

    Dang, Hongyue; Zhou, Haixia; Yang, Jinying; Ge, Huangmin; Jiao, Nianzhi; Luan, Xiwu; Zhang, Chuanlun; Klotz, Martin G

    2013-04-01

    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 PO4(3-) 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.

  3. 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.

  4. Advances in principal factors influencing carbon dioxide adsorption on zeolites

    PubMed Central

    Bonenfant, Danielle; Kharoune, Mourad; Niquette, Patrick; Mimeault, Murielle; Hausler, Robert

    2008-01-01

    We report the advances in the principal structural and experimental factors that might influence the carbon dioxide (CO2) adsorption on natural and synthetic zeolites. The CO2 adsorption is principally govern by the inclusion of exchangeable cations (countercations) within the cavities of zeolites, which induce basicity and an electric field, two key parameters for CO2 adsorption. More specifically, these two parameters vary with diverse factors including the nature, distribution and number of exchangeable cations. The structure of framework also determines CO2 adsorption on zeolites by influencing the basicity and electric field in their cavities. In fact, the basicity and electric field usually vary inversely with the Si/Al ratio. Furthermore, the CO2 adsorption might be limited by the size of pores within zeolites and by the carbonates formation during the CO2 chemisorption. The polarity of molecules adsorbed on zeolites represents a very important factor that influences their interaction with the electric field. The adsorbates that have the most great quadrupole moment such as the CO2, might interact strongly with the electric field of zeolites and this favors their adsorption. The pressure, temperature and presence of water seem to be the most important experimental conditions that influence the adsorption of CO2. The CO2 adsorption increases with the gas phase pressure and decreases with the rise of temperature. The presence of water significantly decreases adsorption capacity of cationic zeolites by decreasing strength and heterogeneity of the electric field and by favoring the formation of bicarbonates. The optimization of the zeolites structural characteristics and the experimental conditions might enhance substantially their CO2 adsorption capacity and thereby might give rise to the excellent adsorbents that may be used to capturing the industrial emissions of CO2. PMID:27877925

  5. 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.

  6. Adsorption energies and prefactor determination for CH3OH adsorption on graphite.

    PubMed

    Doronin, M; Bertin, M; Michaut, X; Philippe, L; Fillion, J-H

    2015-08-28

    In this paper, we have studied adsorption and thermal desorption of methanol CH3OH on graphite surface, with the specific aim to derive from experimental data quantitative parameters that govern the desorption, namely, adsorption energy Eads and prefactor ν of the Polanyi-Wigner law. In low coverage regime, these two values are interconnected and usually the experiments can be reproduced with any couple (Eads, ν), which makes intercomparison between studies difficult since the results depend on the extraction method. Here, we use a method for determining independently the average adsorption energy and a prefactor value that works over a large range of incident methanol coverage, from a limited set of desorption curves performed at different heating rates. In the low coverage regime the procedure is based on a first order kinetic law, and considers an adsorption energy distribution which is not expected to vary with the applied heating rate. In the case of CH3OH multilayers, Eads is determined as 430 meV with a prefactor of 5 × 10(14) s(-1). For CH3OH submonolayers on graphite, adsorption energy of 470 ± 30 meV and a prefactor of (8 ± 3) × 10(16) s(-1) have been found. These last values, which do not change between 0.09 ML and 1 ML initial coverage, suggest that the methanol molecules form island-like structure on the graphite even at low coverage.

  7. Sustained metabolic scope.

    PubMed

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

    1990-03-01

    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.

  8. Scaling metabolic rate fluctuations

    PubMed Central

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

    2007-01-01

    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

  9. 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.

  10. Diffusion Influenced Adsorption Kinetics.

    PubMed

    Miura, Toshiaki; Seki, Kazuhiko

    2015-08-27

    When the kinetics of adsorption is influenced by the diffusive flow of solutes, the solute concentration at the surface is influenced by the surface coverage of solutes, which is given by the Langmuir-Hinshelwood adsorption equation. The diffusion equation with the boundary condition given by the Langmuir-Hinshelwood adsorption equation leads to the nonlinear integro-differential equation for the surface coverage. In this paper, we solved the nonlinear integro-differential equation using the Grünwald-Letnikov formula developed to solve fractional kinetics. Guided by the numerical results, analytical expressions for the upper and lower bounds of the exact numerical results were obtained. The upper and lower bounds were close to the exact numerical results in the diffusion- and reaction-controlled limits, respectively. We examined the validity of the two simple analytical expressions obtained in the diffusion-controlled limit. The results were generalized to include the effect of dispersive diffusion. We also investigated the effect of molecular rearrangement of anisotropic molecules on surface coverage.

  11. 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.

  12. Influence of heat treatment of rayon-based activated carbon fibers on the adsorption of formaldehyde.

    PubMed

    Rong, Haiqin; Ryu, Zhenyu; Zheng, Jingtang; Zhang, Yuanli

    2003-05-15

    The influence of heat treatment of rayon-based activated carbon fibers on the adsorption behavior of formaldehyde was studied. Heat treatment in an inert atmosphere of nitrogen for rayon-based activated carbon fibers (ACFs) resulted in a significant increase in the adsorption capacities and prolongation of breakthrough time on removing of formaldehyde. The effect of different heat-treatment conditions on the adsorption characteristics was investigated. The porous structure parameters of the samples under study were investigated using nitrogen adsorption at the low temperature 77.4 K. The pore size distributions of the samples under study were calculated by density functional theory. With the aid of these analyses, the relationship between structure and adsorption properties of rayon-based ACFs for removing formaldehyde was revealed. Improvement of their performance in terms of adsorption selectivity and adsorption rate for formaldehyde were achieved by heat post-treatment in an inert atmosphere of nitrogen.

  13. Temperature-dependent adsorption of nitrogen on porous vycor glass

    NASA Astrophysics Data System (ADS)

    Huber, Tito E.; Tsou, Hsi Lung

    1998-03-01

    Adsorption isotherms of N2 have been measured in the temperature range from 77 to 120 K in samples of porous vycor glass. From the Brunauer-Emmett-Teller theory the surface layer coverages are determined. These are found to be temperature dependent. When adsorption-isotherm coverage data are expressed as a function of the adsorption potential δμ, the result is roughly temperature independent for coverages ranging from submonolayer to thin film, below capillary condensation. This characteristic curve, which represents the distribution of adsorption sites vs the adsorption potential, is compared with results from two models for the adsorbate: Dubinin's isotherm for microporous solids and its extension to rough surfaces, which places importance on the porosity of the surface, and Halsey's extension of the Frankel-Halsey-Hill isotherm, which takes into account the long-range variations of the substrate adsorption potential. The impact of this work on the interpretation of N2 adsorption data in terms of a surface area is discussed.

  14. 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.

  15. Modeling oxyanion adsorption on ferralic soil, part 2: chromate, selenate, molybdate, and arsenate adsorption.

    PubMed

    Pérez, Claudio; Antelo, Juan; Fiol, Sarah; Arce, Florencio

    2014-10-01

    High levels of oxyanions are found in the soil environment, often as a result of human activity. At high concentrations, oxyanions can be harmful to both humans and wildlife. Information about the interactions between oxyanions and natural samples is essential for understanding the bioavailability, toxicity, and transport of these compounds in the environment. In the present study, the authors investigated the reactivity of different oxyanions (AsO4 , MoO4 , SeO4 , and CrO4 ) at different pH values in 2 horizons of a ferralic soil. By combining available microscopic data on iron oxides with the macroscopic data obtained, the authors were able to use the charge distribution model to accurately describe the adsorption of these 4 oxyanions and thus to determine the surface speciation. The charge distribution model was previously calibrated and evaluated using phosphate adsorption/desorption data. The adsorption behavior on ferralic soil is controlled mainly by the natural iron oxides present, and it is qualitatively analogous to that exhibited by synthetic iron oxides. The highest adsorption was found for arsenate ions, whereas the lowest was found for selenate, with chromate and molybdate ions showing an intermediate behavior.

  16. A (14)C-leucine absorption, distribution, metabolism and excretion (ADME) study in adult Sprague-Dawley rat reveals β-hydroxy-β-methylbutyrate as a metabolite.

    PubMed

    Lee, Anthony J; Beno, David W A; Zhang, Xiaolin; Shapiro, Robin; Mason, Mark; Mason-Bright, Tanita; Surber, Bruce; Edens, Neilé K

    2015-05-01

    Leucine is an essential branched-chain amino acid that acts as a substrate for protein synthesis and as a signaling molecule. Leucine not incorporated into muscle protein is ultimately oxidized through intermediates such as β-hydroxy-β-methylbutyrate (HMB) which itself is reported to enhance muscle mass and function in rats and humans. HMB has been reported in the plasma following oral leucine administration in sheep and pigs but not in Sprague-Dawley rats, the standard preclinical model. Therefore, we conducted radiolabeled absorption, distribution, metabolism and excretion (ADME) studies in rats using a low (3 mg/kg) or high dose (1,000 mg/kg) of (14)C-leucine. Blood, tissue, and urine samples were analyzed for (14)C-leucine and its metabolites by HPLC-MS. Our results show for the first time that (14)C-HMB appears in plasma and urine of rats following an oral dose of (14)C-leucine. (14)C-leucine appears in plasma as (14)C-α-ketoisocaproic acid (KIC) with a slower time course than (14)C-HMB, a putative product of KIC. Further, two novel metabolites of leucine were detected in urine, N-acetyl leucine and glycyl leucine. Mass balance studies demonstrate that excretory routes accounted for no more than 0.9 % of the radiolabel and approximately 61 % of the dose was recovered in the carcass. Approximately 65 % of the dose was recovered in total, suggesting that approximately one-third of the leucine dose is oxidized to CO2. In conclusion, this study demonstrates endogenous production of HMB from leucine in adult rats, a standard preclinical model used to guide design of clinical trials in nutrition.

  17. Tissue distribution, metabolism and hepatic tissue injury in Chinese lizards (Eremias argus) after a single oral administration of lambda-cyhalothrin.

    PubMed

    Chang, Jing; Li, Jitong; Wang, Huili; Wang, Yinghuan; Guo, Baoyuan; Yin, Jing; Hao, Weiyu; Li, Wei; Li, Jianzhong; Xu, Peng

    2016-11-01

    Lambda-cyhalothrin (LCT) is a widely used pyrethroid with neurotoxicity. However, little is known about the toxicokinetics of LCT in reptiles. In this study, the absorption, distribution, metabolism and excretion of LCT in Chinese lizards (Eremias Argus) were determined following a single dose (10 mg kg(-1)) treatment. In the liver, brain, gonads and skin, LCT levels peaked within several hours and then decreased rapidly. However, the concentration of LCT gradually increased in the fat tissue. More than 90% of the LCT dose was excreted in the faeces. One LCT metabolite, 3-phenoxybenzoic acid (PBA), was detected in lizard plasma and tissues. PBA preferentially accumulates in the brain and plasma. The half-life of PBA in the brain was 3.2 days, which was 35.4-fold greater than that of LCT. In the plasma, the concentration of PBA was significantly higher than that of LCT. The bioaccumulation of LCT in tissues was enantioselective, and the enantiomeric fractions (EF) ranged from 0.72 to 0.26. The preferential accumulation of enantiomers changed according to exposure time, but the reasons behind this phenomenon were not clear. For pathological analysis, vacuolation of the cytoplasm and large areas of necrosis were observed in the liver sections after 168 h of dosing. The liver tissues exhibited both decreases in the hepatosomatic index and histopathological lesions during the exposure period. In this study, the effect concentration of LCT in lizards was 200-fold lower than its LD50 value used in risk assessments for birds. These results may provide additional information for the risk assessment of LCT for reptiles and indicate that birds may not be an ideal surrogate for reptile toxicity evaluation.

  18. 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.

  19. 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.

  20. [Adsorption behavior of exogenous thorium on soil contaminated by rare earth industries].

    PubMed

    Guo, Peng-ran; Jia, Xiao-yu; Duan, Tai-cheng; Qiu, Rong-liang; Chen, Hang-ting

    2009-10-15

    The adsorption behavior of exogenous thorium on soil was studied to evaluate the contaminated risk on soil. The adsorption capacity, equilibrium time, distribution coefficient and desorption ability were investigated by the experiments of static adsorption. The strong adsorption ability of exogenous thorium on soil samples was observed by high adsorption ratio (> 92%) and low desorption ratio (< 5%) in equilibrium, and the biggest distribution coefficient was over 10(4). The adsorption capacity and equilibrium time were related to soil properties. According to the results of adsorption, Freundlich equation (r > or = 0.9167) and Elovich equation (R2 > or = 0.8980) were primely fit for describing the thermodynamics and kinetics of the adsorption of exogenous thorium on soil samples, respectively, which indicated that the adsorption was belonged to the nonlinear adsorption, and was affected by the diffusion of thorium on soil surface and in mineral interbed. Sequential extraction procedure was employed to evaluate the bound fractions of exogenous thorium adsorbed on soil samples. Based on the extracted results of thorium fractions, exogenous thorium was presented in the labile nonresidual fractions (over 58%) at the low initial concentration (10(-7) - 10(-6) mol x L(-1)), and nonresidual fractions enhanced with the increase of the initial amount, meanwhile more exogenous throium was transferred to the stable residual fractions.

  1. Models of adsorption at a line of three-phase contact.

    PubMed

    Widom, B

    2006-11-09

    Two model density distributions at a line of three-phase contact for which the adsorptions are readily calculated are analyzed. One of them provides a numerical illustration of a recently found surprising fact about the thermodynamics of adsorption at such contact lines. A form of the line analogue of the Gibbs adsorption equation is conjectured, and it is noted that the conjecture is in principle testable by computer simulation and by experiment.

  2. 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.

  3. 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)

  4. [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.

  5. 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.

  6. Nucleic acid distribution pattern as a possible biomarker for metabolic activities of neoplastic cells: a digitally-aided fluorescence microscopy study on normal and neoplastic lymphocytes of acute and chronic canine lymphocytic leukemia

    PubMed Central

    Isitor, Godwin N; Campbell, Mervyn; Nayak, Shivananda B

    2009-01-01

    Background Metabolic states of neoplastic cells are increasingly being relied upon for diagnostic and prognostic assessment of neoplastic conditions. The nucleic acid distribution pattern of cells in general, in terms of degree of condensation of the nuclear chromatin and overall spread of the nucleic acid within the nuclear and cytoplasmic compartments, can reflect the metabolic state of the cell. This simple but logical concept appears not be put into consideration to date as numerous attempts are being made towards formulating reliable biomarkers for rapid diagnosis, prognosis and subsequent therapeutic interventions for neoplastic conditions. We comparatively evaluated nucleic acid distribution patterns of normal lymphocytes and neoplastic cells of lymphocytic lineage, employing light and fluorescence microscopy procedures, as well as digital imaging analytical methods. Results The results demonstrate distinctiveness in the pattern of nucleic acid distribution for the normal lymphocytes and three lymphocytic neoplastic cell-types of canine lymphocytic leukemia that are categorized as small, intermediate and large neoplastic lymphocytes. Variably-shaped cytoplasmic processes laden with single-stranded nucleic acids (SSNA) were observed for the small and intermediate-sized neoplastic lymphocytes, compared with large neoplastic lymphocytes and the normal lymphocytes; the latter two categories of cells being virtually devoid of similar processes. Prominent cytoplasmic and nuclear clumps of SSNA, indicative of a higher rate of metabolic activity, were also observed within the neoplastic cells compared with fewer and narrower SSNA of the normal cells. Conclusion The comparative relative increases of SSNA in cytoplasmic processes and other cellular areas of small and intermediate-sized neoplastic lymphocytes is reflective of greater metabolic activity in neoplastic cells in general compared with their normal cellular counterparts. PMID:19432993

  7. Ibuprofen adsorption in four agricultural volcanic soils.

    PubMed

    Estevez, Esmeralda; Hernandez-Moreno, Jose Manuel; Fernandez-Vera, Juan Ramon; Palacios-Diaz, Maria Pino

    2014-01-15

    Ibuprofen (IB) is a high environmental risk drug and one of the most frequently prescribed in human medicine. Recently, IB has been detected in Gran Canaria in reclaimed water for irrigation and in groundwater. Adsorption was studied in four volcanic soils from three islands of the Canarian Archipelago. Once the biodegradation process has been excluded from the experimental conditions, a batch method was applied using initial concentrations of 1-5-10-20-50-100-200 mg L(-1) and two soil/water ratios (w/V): 1:5 (OECD, 2000) and 1:1. Non-linear and linearized Langmuir and Freundlich equations were well fitted. The wide IB range tested in our batch studies allowed us to measure experimental adsorption values close to the maximum adsorption capacity (S(max)) as estimated by Langmuir, making it possible thereby to validate the use of the Langmuir equation when there is a burst of contamination at high concentration. The distribution coefficient (Kd), S(max) and Retardation Factor (RF) varied from 0.04 to 0.5 kg L(-1), 4-200 mgk g(-1) and 1.2-1.9, respectively. The lowest S(max) and Kd values were found for the 1:1S/W ratio whereas most batch studies employ 1:5S/W ratios, thus obtaining higher adsorption parameters than when considering field conditions (1:1). Despite the high anion retention of andic soils, similar Kd and RF to those reported for other soils were obtained in 1:5, while high S(max) was found. Our results demonstrate that IB adsorption in volcanic areas responds not only to the soil properties commonly cited in adsorption studies, but also depends on andic properties, sorbent concentration and Dissolved Organic Carbon, the higher values of which are related to the lower Kd and S(max). The low RF and low detection frequency of the IB in groundwater suggests that a) reclaimed water irrigation is not the main source of IB, and b) the existence of some uncontrolled water disposal points in the zone.

  8. 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.

  9. 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.

  10. 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 ...

  11. 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.

  12. 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.

  13. 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.

  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. Investigation kinetics mechanisms of adsorption malachite green onto activated carbon.

    PubMed

    Onal, Y; Akmil-Başar, C; Sarici-Ozdemir, C

    2007-07-19

    Lignite was used to prepare activated carbon (T3K618) by chemical activation with KOH. Pore properties of the activated carbon such as BET surface area, pore volume, pore size distribution, and pore diameter were characterized by t-plot based on N2 adsorption isotherm. BET surface area of activated carbon is determined as 1000 m2/g. Adsorption capacity of malachite green (MG) onto T3K618 activated carbon was investigated in a batch system by considering the effects of various parameters like initial concentration (100, 150 and 200 mg/L) and temperature (25, 40 and 50 degrees C). The adsorption process was relatively fast and equilibrium was reached after about 20 min for 100, 150 mg/L at all adsorption temperature. Equilibrium time for 200 mg/L was determined as 20 min and 40 min at 298, 313 and 323 K, respectively. Simple mass and kinetic models were applied to the experimental data to examine the mechanisms of adsorption and potential rate controlling steps such as external mass transfer, intraparticle diffusion. Pseudo second-order model was found to explain the kinetics of MG adsorption most effectively. It was found that both mass transfer and pore diffusion are important in determining the adsorption rates. The intraparticle diffusion rate constant, external mass transfer coefficient, film and pore diffusion coefficient at various temperatures were evaluated. The activation energy (Ea) was determined as 48.56, 63.16, 67.93 kJ/mol for 100, 150, 200 mg/L, respectively. The Langmiur and Freundlich isotherm were used to describe the adsorption equilibrium studies at different temperatures. Langmiur isotherm shows better fit than Freundlich isotherm in the temperature range studied. The thermodynamic parameters, such as DeltaG degrees, DeltaS and DeltaH degrees were calculated. The thermodynamics of dyes-T3K618 system indicates endothermic process.

  16. Pulmonary metabolism of foreign compounds: Its role in metabolic activation

    SciTech Connect

    Cohen, G.M. )

    1990-04-01

    The lung has the potential of metabolizing many foreign chemicals to a vast array of metabolites with different pharmacological and toxicological properties. Because many chemicals require metabolic activation in order to exert their toxicity, the cellular distribution of the drug-metabolizing enzymes in a heterogeneous tissue, such as the lung, and the balance of metabolic activation and deactivation pathways in any particular cell are key factors in determining the cellular specificity of many pulmonary toxins. Environmental factors such as air pollution, cigarette smoking, and diet markedly affect the pulmonary metabolism of some chemicals and, thereby, possibly affect their toxicity.

  17. 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.

  18. Galactose adsorption on Ru(0001)

    NASA Astrophysics Data System (ADS)

    Alatalo, Matti; Puisto, Mikko

    2014-03-01

    In order to understand the valorisation of biomass, it is essential to study the behavior of sugar molecules on catalytic surfaces. We have studied the adsorption of galactose molecules on the Ru(0001) surface using first principles calculations. We present results for the fully relaxed configurations of the molecule at different adsorption sites. We also compare the effect of the inclusion of the van der Waals interactions on both the energetics of the free galactose molecule and the adsorption energy of galactose on Ru(0001). We compare our results, obtained using periodically repeated supercells, to those obtained with cluster calculations.

  19. Competitive adsorption of metal cations onto two gram positive bacteria: testing the chemical equilibrium model

    NASA Astrophysics Data System (ADS)

    Fowle, David A.; Fein, Jeremy B.

    1999-10-01

    In order to test the ability of a surface complexation approach to account for metal-bacteria interactions in near surface fluid-rock systems, we have conducted experiments that measure the extent of adsorption in mixed metal, mixed bacteria systems. This study tests the surface complexation approach by comparing estimated extents of adsorption based on surface complexation modeling to those we observed in the experimental systems. The batch adsorption experiments involved Ca, Cd, Cu, and Pb adsorption onto the surfaces of 2 g positive bacteria: Bacillus subtilis and Bacillus licheniformis. Three types of experiments were performed: 1. Single metal (Ca, Cu, Pb) adsorption onto a mixture of B. licheniformis and B. subtilis; 2. mixed metal (Cd, Cu, and Pb; Ca and Cd) adsorption onto either B. subtilis or B. licheniformis; and 3. mixed or single metal adsorption onto B. subtilis and B. licheniformis. %Independent of the experimental results, and based on the site specific stability constants for Ca, Cd, Cu, and Pb interactions with the carboxyl and phosphate sites on B. licheniformis and B. subtilis determined by Fein et al. (1997), by Daughney et al. (1998) and in this study, we estimate the extent of adsorption that is expected in the above experimental systems. Competitive cation adsorption experiments in both single and double bacteria systems exhibit little adsorption at pH values less than 4. With increasing pH above 4.0, the extent of Ca, Cu, Pb and Cd adsorption also increases due to the increased deprotonation of bacterial surface functional groups. In all cases studied, the estimated adsorption behavior is in excellent agreement with the observations, with only slight differences that were within the uncertainties of the estimation and experimental procedures. Therefore, the results indicate that the use of chemical equilibrium modeling of aqueous metal adsorption onto bacterial surfaces yields accurate predictions of the distribution of metals in complex

  20. Intraparticle heat and mass transfer characteristics of silica-gel/water vapor adsorption

    SciTech Connect

    Yamamoto, Eri; Watanabe, Fujio; Hasatani, Masanobu

    1999-07-01

    Recently, highly efficient energy utilization systems which extensively employ adsorption phenomena such as pressure swing adsorption, heat storage, adsorption heat pump, etc. are being regarded as one of the countermeasures for environmental issues such as green house effect and ozone layer destruction. An Adsorption Heat Pump (AHP) has been investigated as one of the important techniques via which cold heat energy is obtained from waste thermal energy below 373K without using electricity and CFCs. An AHP normally consists of an adsorber and an evaporator/condenser and cold heat energy is generated by latent heat of evaporation during adsorption process. For realizing the AHP technology, it has been pointed out that the development of an adsorber with optimum heat and mass transfer characteristics is essentially important. In this study, experimental studies were carried out which was based on the data of temperature inside the adsorbent particle and adsorptivity profiles at the adsorption/desorption process by volumetric method. To clarify adsorption mechanism relatively large silica-gel particle (7 mm f) was used. Temperature distribution in the particle is determined at the center, at one half radius in the radial direction and at the surface by using very thin (30 mm f) thermocouples. The temperatures at these points simultaneously increase/decrease as soon as the adsorption/desorption started, reached their respective maximum/minimum values and then return to initial temperature. The temperature profiles for the adsorption process show that the temperature at the surface is initially slightly higher than the other two points. All three points reached their respective maximum temperature at the same time with the temperature at the center point the highest and at the surface the lowest. The temperature profiles during the desorptive process are almost exactly the opposite to that of the adsorption process. This shows that the adsorption phenomena can take

  1. 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

  2. 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.

  3. 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...

  4. 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

  5. Adsorption of plutonium oxide nanoparticles.

    PubMed

    Schmidt, Moritz; Wilson, Richard E; Lee, Sang Soo; Soderholm, L; Fenter, P

    2012-02-07

    Adsorption of monodisperse cubic plutonium oxide nanoparticles ("Pu-NP", [Pu(38)O(56)Cl(x)(H(2)O)(y)]((40-x)+), with a fluorite-related lattice, approximately 1 nm in edge size) to the muscovite (001) basal plane from aqueous solutions was observed in situ (in 100 mM NaCl background electrolyte at pH 2.6). Uptake capacity of the surface quantified by α-spectrometry was 0.92 μg Pu/cm(2), corresponding to 10.8 Pu per unit cell area (A(UC)). This amount is significantly larger than that of Pu(4+) needed for satisfying the negative surface charge (0.25 Pu(4+) for 1 e(-)/A(UC)). The adsorbed Pu-NPs cover 17% of the surface area, determined by X-ray reflectivity (XR). This correlates to one Pu-NP for every 14 unit cells of muscovite, suggesting that each particle compensates the charge of the unit cells onto which it adsorbs as well as those in its direct proximity. Structural investigation by resonant anomalous X-ray reflectivity distinguished two different sorption states of Pu-NPs on the surface at two different regimes of distance from the surface. A fraction of Pu is distributed within 11 Å from the surface. The distribution width matches the Pu-NP size, indicating that this species represents Pu-NPs adsorbed directly on the surface. Beyond the first layer, an additional fraction of sorbed Pu was observed to extend more broadly up to more than 100 Å from the surface. This distribution is interpreted as resulting from "stacking" or aggregation of the nanoparticles driven by sorption and accumulation of Pu-NPs at the interface although these Pu-NPs do not aggregate in the solution. These results are the first in situ observation of the interaction of nanoparticles with a charged mineral-water interface yielding information important to understanding the environmental transport of Pu and other nanophase inorganic species.

  6. Multilayer adsorption on fractal surfaces.

    PubMed

    Vajda, Péter; Felinger, Attila

    2014-01-10

    Multilayer adsorption is often observed in liquid chromatography. The most frequently employed model for multilayer adsorption is the BET isotherm equation. In this study we introduce an interpretation of multilayer adsorption measured on liquid chromatographic stationary phases based on the fractal theory. The fractal BET isotherm model was successfully used to determine the apparent fractal dimension of the adsorbent surface. The nonlinear fitting of the fractal BET equation gives us the estimation of the adsorption equilibrium constants and the monolayer saturation capacity of the adsorbent as well. In our experiments, aniline and proline were used as test molecules on reversed phase and normal phase columns, respectively. Our results suggest an apparent fractal dimension 2.88-2.99 in the case of reversed phase adsorbents, in the contrast with a bare silica column with a fractal dimension of 2.54.

  7. 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.

  8. Adsorption of ions on surfaces modified with brushes of polyampholytes

    NASA Astrophysics Data System (ADS)

    Borówko, M.; Sokołowski, S.; Staszewski, T.; Sokołowska, Z.; Ilnytskyi, J. M.

    2012-08-01

    We apply density functional theory to study adsorption of ions, treated in the framework of the restricted primitive model (RPM), on surfaces modified by tethered polyampholytes. The residual electrostatic contribution to the free energy functional is approximated by using the approach proposed by Wang et al. [J. Phys.: Condens. Matter 23, 175002 (2011)], 10.1088/0953-8984/23/17/175002 for simple nonuniform RPMs systems. Our research concentrates on the problems how the distribution of the charges within chains of polyampholytes changes the selectivity of adsorption of ions species, the structure of the surface layer, and its electric properties.

  9. A solvable model for localized adsorption in a Coulomb system

    SciTech Connect

    Rosinberg, M.L.; Blum, L.; Lebowitz, J.L.

    1986-07-01

    A model for an interface with localized adsorption is presented, in which the surface has a distribution of sticky adhesive sites in contact with a Coulomb fluid. Contrary to the current literature on the electrical double layer the surface charge is in dynamic equilibrium with the bulk fluid. The sum rules obeyed by the one- and two-body correlation functions are investigated. Explicit results are obtained for a solvable model, the two-dimensional one-component plasma at reduced temperature 2. The effect of the granularity of the adsorbed charge on the adsorption isotherm is discussed.

  10. Highlights From the American Association of Pharmaceutical Scientists/ International Transporter Consortium Joint Workshop on Drug Transporters in Absorption, Distribution, Metabolism, and Excretion: From the Bench to the Bedside - Clinical Pharmacology Considerations.

    PubMed

    Ronaldson, P T; Bauer, B; El-Kattan, A F; Shen, H; Salphati, L; Louie, S W

    2016-11-01

    The American Association of Pharmaceutical Scientists/International Transporter Consortium Joint Workshop on Drug Transporters in absorption, distribution, metabolism, and excretion was held with the objective of discussing innovative advances in transporter pharmacology. Specific topics included (i) transporters at the blood-brain barrier (BBB); (ii) emerging transport proteins; (iii) recent advances in achieving hepatoselectivity and optimizing clearance for organic anion-transporting polypeptide (OATP) substrates; (iv) utility of animal models for transporter studies; and (v) clinical correlation of transporter polymorphisms. Here, we present state-of-the-art highlights from this workshop in these key areas of focus.

  11. Adsorption hysteresis in nanopores

    PubMed

    Neimark; Ravikovitch; Vishnyakov

    2000-08-01

    Capillary condensation hysteresis in nanopores is studied by Monte Carlo simulations and the nonlocal density functional theory. Comparing the theoretical results with the experimental data on low temperature sorption of nitrogen and argon in cylindrical channels of mesoporous siliceous molecular sieves of MCM-41 type, we have revealed four qualitatively different sorption regimes depending on the temperature and pore size. As the pore size increases at a given temperature, or as the temperature decreases at a given pore size, the following regimes are consequently observed: volume filling without phase separation, reversible stepwise capillary condensation, irreversible capillary condensation with developing hysteresis, and capillary condensation with developed hysteresis. We show that, in the regime of developed hysteresis (pores wider than 5 nm in the case of nitrogen sorption at 77 K), condensation occurs spontaneously at the vaporlike spinodal while desorption takes place at the equilibrium. A quantitative agreement is found between the modeling results and the experimental hysteresis loops formed by the adsorption-desorption isotherms. The results obtained provide a better understanding of the general behavior of confined fluids and the specifics of sorption and phase transitions in nanomaterials.

  12. Surfactant adsorption kinetics in microfluidics

    PubMed Central

    Riechers, Birte; Maes, Florine; Akoury, Elias; Semin, Benoît; Gruner, Philipp; Baret, Jean-Christophe

    2016-01-01

    Emulsions are metastable dispersions. Their lifetimes are directly related to the dynamics of surfactants. We design a microfluidic method to measure the kinetics of adsorption of surfactants to the droplet interface, a key process involved in foaming, emulsification, and droplet coarsening. The method is based on the pH decay in the droplet as a direct measurement of the adsorption of a carboxylic acid surfactant to the interface. From the kinetic measurement of the bulk equilibration of the pH, we fully determine the adsorption process of the surfactant. The small droplet size and the convection during the droplet flow ensure that the transport of surfactant through the bulk is not limiting the kinetics of adsorption. To validate our measurements, we show that the adsorption process determines the timescale required to stabilize droplets against coalescence, and we show that the interface should be covered at more than 90% to prevent coalescence. We therefore quantitatively link the process of adsorption/desorption, the stabilization of emulsions, and the kinetics of solute partitioning—here through ion exchange—unraveling the timescales governing these processes. Our method can be further generalized to other surfactants, including nonionic surfactants, by making use of fluorophore–surfactant interactions. PMID:27688765

  13. Surfactant adsorption kinetics in microfluidics

    NASA Astrophysics Data System (ADS)

    Riechers, Birte; Maes, Florine; Akoury, Elias; Semin, Benoît; Gruner, Philipp; Baret, Jean-Christophe

    2016-10-01

    Emulsions are metastable dispersions. Their lifetimes are directly related to the dynamics of surfactants. We design a microfluidic method to measure the kinetics of adsorption of surfactants to the droplet interface, a key process involved in foaming, emulsification, and droplet coarsening. The method is based on the pH decay in the droplet as a direct measurement of the adsorption of a carboxylic acid surfactant to the interface. From the kinetic measurement of the bulk equilibration of the pH, we fully determine the adsorption process of the surfactant. The small droplet size and the convection during the droplet flow ensure that the transport of surfactant through the bulk is not limiting the kinetics of adsorption. To validate our measurements, we show that the adsorption process determines the timescale required to stabilize droplets against coalescence, and we show that the interface should be covered at more than 90% to prevent coalescence. We therefore quantitatively link the process of adsorption/desorption, the stabilization of emulsions, and the kinetics of solute partitioning—here through ion exchange—unraveling the timescales governing these processes. Our method can be further generalized to other surfactants, including nonionic surfactants, by making use of fluorophore-surfactant interactions.

  14. 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

  15. 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

    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.

  16. Macromolecule simulation and CH4 adsorption mechanism of coal vitrinite

    NASA Astrophysics Data System (ADS)

    Yu, Song; Yan-ming, Zhu; Wu, Li

    2017-02-01

    The microscopic mechanism of interactions between CH4 and coal macromolecules is of significant practical and theoretical importance in CBM development and methane storage. Under periodic boundary conditions, the optimal energy configuration of coal vitrinite, which has a higher torsion degree and tighter arrangement, can be determined by the calculation of molecular mechanics (MM) and molecular dynamics (MD), and annealing kinetics simulation based on ultimate analysis, 13C NMR, FT IR and HRTEM. Macromolecular stabilization is primarily due to the van der Waals energy and covalent bond energy, mainly consisting of bond torsion energy and bond angle energy. Using the optimal configuration as the adsorbent, GCMC simulation of vitrinite adsorption of CH4 is conducted. A saturated state is reached after absorbing 17 CH4s per coal vitrinite molecule. CH4 is preferentially adsorbed on the edge, and inclined to gathering around the branched chains of the inner vitrinite sites. Finally, the adsorption parameters are calculated through first principle DFT. The adsorbability order is as follows: aromatic structure> heteroatom rings > oxygen functional groups. The adsorption energy order is as follows: Top < Bond < Center, Up < Down. The order of average RDF better reflects the adsorption ability and that of [-COOH] is lower than those of [sbnd Cdbnd O] and [Csbnd Osbnd C]. CH4 distributed in the distance of 0.99-16 Å to functional groups in the type of monolayer adsorption and the average distance order manifest as [sbnd Cdbnd O] (1.64 Å) < [Csbnd Osbnd C] (1.89 Å) < [sbnd COOH] (3.78 Å) < [-CH3] (4.11 Å) according to the average RDF curves. CH4 enriches around [sbnd Cdbnd O] and [Csbnd O-C] whereas is rather dispersed about [-COOH] and [CH3]. Simulation and experiment data are both in strong agreement with the Langmuir and D-A isothermal adsorption model and the D-A model fit better than Langmuir model. Preferential adsorption sites and orientations in vitrinite are

  17. New BET-like models for heterogeneous adsorption in microporous adsorbents

    NASA Astrophysics Data System (ADS)

    Milewska-Duda, Janina; Duda, Jan T.

    2002-08-01

    The paper presents a package of isotherm equations for heterogeneous adsorption aimed at the analysis of pore structure of sub- and microporous materials. One considers adsorption of small nearly spherical molecules in irregular pores of molecular size. The generalized BET theory is exploited respecting restrictions for multilayer adsorption (LBET approach). The model is based on thermodynamic relationships expressing changes of internal energy and configurational entropy due to the process. The adsorption energy is evaluated by using the Berthelot rule, and corrected with a factor Z a representing a fraction of effective contacts enabling full adsorbent-adsorbate interaction. Side adsorbate-adsorbate interactions are neglected and constrained multilayer adsorption is considered. One assumes the values for Z a to be uniformly distributed over the first layer adsorption sites within a range depending on the pore size. New models make it possible to obtain information on structure of pores and adsorption mechanisms on the basis of adsorption isotherms of small molecule adsorbates. Exemplary results of new models application for adsorption of CO 2 and CH 4 in an activated carbon are discussed.

  18. 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.

  19. Mechanism of adsorption of anionic dye from aqueous solutions onto organobentonite.

    PubMed

    Ma, Jianfeng; Cui, Bingying; Dai, Juan; Li, Dinglong

    2011-02-28

    Organobentonite is suggested as potential super-sorbents for the removal of dyes from wastewater. All kinds of organobentonites are synthesized to adsorb dyes; however, the mechanism of the adsorption is still unclear. In this paper, organobentonites were first modified with hexadecyltrimethylammonium bromide at various amounts to reveal the adsorption mechanism. Subsequently, four kinds of organobentonites were utilized to adsorb acid dyes. Results show that the main mechanism of the adsorption of acid dye is an anionic exchange. The counter-ion bromide in the organobentonite was replaced by the dye anion. The study reveals that the adsorption capacity of organobentonite is affected by the surfactant alkyl chain length. When the longer alkyl chain surfactant was modified, bentonite showed higher adsorption capacity. Specific surface areas had no effect on the adsorption. However, the XRD patterns show that interlamellar distance and lamellar distribution have some effects on the adsorption. High adsorption capacity and low residual concentration were obtained by the organobentonite adsorbents. The revelation of the adsorption mechanism makes it possible to obtain more novel and suitable organobentonite adsorbents for anionic dye removal from wastewater.

  20. Characterization of a Polyamine Microsphere and Its Adsorption for Protein

    PubMed Central

    Wang, Feng; Liu, Pei; Nie, Tingting; Wei, Huixian; Cui, Zhenggang

    2013-01-01

    A novel polyamine microsphere, prepared from the water-in-oil emulsion of polyethylenimine, was characterized. The investigation of scanning electron microscopy showed that the polyamine microsphere is a regular ball with a smooth surface. The diameter distribution of the microsphere is 0.37–4.29 μm. The isoelectric point of the microsphere is 10.6. The microsphere can adsorb proteins through the co-effect of electrostatic and hydrophobic interactions. Among the proteins tested, the highest value of adsorption of microsphere, 127.8 mg·g−1 microsphere, was obtained with lipase. In comparison with other proteins, the hydrophobic force is more important in promoting the adsorption of lipase. The microsphere can preferentially adsorb lipase from an even mixture of proteins. The optimum temperature and pH for the selective adsorption of lipase by the microsphere was 35 °C and pH 7.0. PMID:23344018

  1. 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.

  2. 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.

  3. Electrokinetic investigation of surfactant adsorption.

    PubMed

    Bellmann, C; Synytska, A; Caspari, A; Drechsler, A; Grundke, K

    2007-05-15

    Fuerstenau [D.W. Fuerstenau, in: M.L. Hair (Ed.), Dekker, New York, 1971, p. 143] has already discussed the role of hydrocarbon chain of surfactants, the effect of alkyl chain length, chain structure and the pH of the solution on the adsorption process of surfactants. Later Kosmulski [M. Kosmulski, Chemical Properties of Material Surfaces, Surfactant Science Series, vol. 102, Dekker, New York, Basel, 2001] included the effect of surfactant concentration, equilibration time, temperature and electrolyte in his approaches. Certainly, the character of the head groups of the surfactant and the properties of the adsorbent surface are the basis for the adsorption process. Different surfactants and adsorbents cause different adsorption mechanisms described firstly by Rosen [M.J. Rosen, Surfactants and Interfacial Phenomena, second ed., Wiley, New York, 1989]. These adsorption mechanisms and their influencing factors were studied by electrokinetic investigations. Here only changes of the charges at the surfaces could be detected. To control the results of electrokinetic investigations they were compared with results from ellipsometric measurements. In the case of surfactant adsorption the chain length was vitally important. It could be shown by the adsorption of alkyl trimethyl ammonium bromides onto polymer films spin coated at wafer surfaces. The influence of the chain length depending on surface properties of the polymer film was studied. Streaming potential measurements were applied for these investigations. The obtained results enabled us to calculate the molar cohesive free energy per mol of CH2-group in the alkaline chain of the surfactant if all other specific adsorption effects were neglected.

  4. 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.

  5. Adsorption of oxygen on W/100/ - Adsorption kinetics and structure

    NASA Technical Reports Server (NTRS)

    Bauer, E.; Poppa, H.; Viswanath, Y.

    1976-01-01

    The adsorption of oxygen on W(100) single-crystal surfaces is studied by Auger electron spectroscopy (AES), flash desorption, low-energy electron diffraction (LEED), and retarding-field work-function measurements. The AES results reveal stepwise changes in the sticking coefficients in the coverage range 0 to 1 and activated adsorption at higher coverages. Upon room-temperature adsorption, a series of complex LEED patterns is observed. In layers adsorbed at 1050 K and cooled to room temperature, the p(2 x 1) structure is the first ordered structure observed. This structure shows a reversible order-disorder transition between 700 and 1000 K and is characterized by a work function which is lower than that of the clean surface. Heating room-temperature adsorbates changes their structure irreversibly. At temperatures below 750 K, some new structures are observed.

  6. Synthesis and adsorption of functionalized polystyrenes

    SciTech Connect

    Iyengar, D.R.

    1992-12-31

    The effect of specifically interacting functional groups located at the chain ends of polystyrene on the absorption rate, adsorbance, graft density and surface excess are discussed from cyclohexane, a theta solvent and toluene. Polystyrenes with hydroxyl and carboxylic acid-end-groups in narrow molecular weight distribution are synthesized by anionic polymerization of styrene followed by suitable termination reactions. Thin layer chromatography (TLC) is developed as an analytical technique to predict trends in the adsorption of the polymers in a range of solvents. In particular the information about the localization of the end-group and therefore different chain architectures at the interface are inferred from this simple technique. Adsorption isotherms are obtained for each of the functionalized polymers of four different molecular weights, the selection of which was based on the TLC results. Kinetics of adsorption and the adsorbance data are determined by liquid counting of tritium labelled polymers. Graft density and surface excess data are calculated from the adsorbance data and other known parameters. It is shown, from these data, that polystyrenes with a carboxylic acid end-group form weakly stretched brushes at the glass-cyclohexane interface and mushrooms at the glass-toluene interface a result consistent with the higher osmotic repulsions towards packing in good solvents. Polystyrenes with function groups at both the chain ends are hypothesized to form a range of structures from those dominated by tails at higher concentrations to those dominated by loops and trains at lower solution concentrations. At higher molecular weights it is shown that functionalized a result consistent with the TLC predictions. Hydroxyl end-group is shown to be an ineffective sticky foot from its adsorbance vis-a-vis polystyrene.

  7. 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

    2010-09-07

    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.

  8. Adsorptive desulfurization by activated alumina.

    PubMed

    Srivastav, Ankur; Srivastava, Vimal Chandra

    2009-10-30

    This study reports usage of commercial grade activated alumina (aluminum oxide) as adsorbent for the removal of sulfur from model oil (dibenthiophene (DBT) dissolved in n-hexane). Bulk density of alumina was found to be 1177.77 kg/m(3). The BET surface area of alumina was found to decrease from 143.6 to 66.4 m(2)/g after the loading of DBT at optimum conditions. The carbon-oxygen functional groups present on the surface of alumina were found to be effective in the adsorption of DBT onto alumina. Optimum adsorbent dose was found to be 20 g/l. The adsorption of DBT on alumina was found to be gradual process, and quasi-equilibrium reached in 24 h. Langmuir isotherm best represented the equilibrium adsorption data. The heat of adsorption and change in entropy for DBT adsorption onto alumina was found to be 19.5 kJ/mol and 139.2 kJ/mol K, respectively.

  9. Reduced protein adsorption by osmolytes.

    PubMed

    Evers, Florian; Steitz, Roland; Tolan, Metin; Czeslik, Claus

    2011-06-07

    Osmolytes are substances that affect osmosis and are used by cells to adapt to environmental stress. Here, we report a neutron reflectivity study on the influence of some osmolytes on protein adsorption at solid-liquid interfaces. Bovine ribonuclease A (RNase) and bovine insulin were used as model proteins adsorbing at a hydrophilic silica and at a hydrophobic polystyrene surface. From the neutron reflectivity data, the adsorbed protein layers were characterized in terms of layer thickness, protein packing density, and adsorbed protein mass in the absence and presence of urea, trehalose, sucrose, and glycerol. All data point to the clear effect of these nonionic cosolvents on the degree of protein adsorption. For example, 1 M sucrose leads to a reduction of the adsorbed amount of RNase by 39% on a silica surface and by 71% on a polystyrene surface. Trehalose was found to exhibit activity similar to that of sucrose. The changes in adsorbed protein mass can be attributed to a decreased packing density of the proteins in the adsorbed layers. Moreover, we investigated insulin adsorption at a hydrophobic surface in the absence and presence of glycerol. The degree of insulin adsorption is decreased by even 80% in the presence of 4 M of glycerol. The results of this study demonstrate that nonionic cosolvents can be used to tune and control nonspecific protein adsorption at aqueous-solid interfaces, which might be relevant for biomedical applications.

  10. A biological oil adsorption filter.

    PubMed

    Pasila, Antti

    2004-12-01

    A new oil adsorption method called adsorption filtration (AF) has been developed. It is a technology where by oil residues can be cleaned from water by running it through a simple filter made from freeze treated, dried, milled and then fragmented plant material. By choosing suitable plants and fragmentation sizes it is possible to produce filters, which pass water but adsorb oil. The aim of this study was to investigate the possibilities of manufacturing oil adsorbing filter materials from reed canary grass (Phalaris arundinacea), flax (Linum usitatissimum L.) or hemp fibre (Cannabis sativa L.). The oil (80 ml) was mixed with de-ionised water (200 ml) and this mixture was filtered through 10 or 20 g adsorption filters. Fine spring harvested hemp fibre (diameter less than 1 mm) and reed canary grass fragments adsorb 2-4 g of oil per gram of adsorption material compared to 1-3 g of water. Adsorption filtration is thus a novel way of gathering spilled oil in shallow coastal waters before the oil reaches the shore.

  11. 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.

  12. Metal adsorption on mosses: Toward a universal adsorption model.

    PubMed

    González, A G; Pokrovsky, O S

    2014-02-01

    This study quantifies the adsorption of heavy metals on 4 typical moss species used for environmental monitoring in the moss bag technique. The adsorption of Cu(2+), Cd(2+), Ni(2+), Pb(2+) and Zn(2+) onto Hypnum sp., Sphagnum sp., Pseudoscleropodium purum and Brachytecium rutabulum has been investigated using a batch reactor in a wide range of pH (1.3-11.0) and metal concentrations in solution (1.6μM-3.8mM). A Linear Programming Model (LPM) was applied for the experimental data to derive equilibrium constants and the number of surface binding sites. The surface acid-base titration performed for 4 mosses at a pH range of 3-10 in 0.1M NaNO3 demonstrated that Sphagnum sp. is the most efficient adsorbent as it has the maximal number of proton-binding sites on the surface (0.65mmol g(-1)). The pKa computed for all the moss species suggested the presence of 5 major functional groups: phosphodiester, carboxyl, phosphoryl, amine and polyphenols. The results of pH-edge experiments demonstrated that B. rutabulum exhibits the highest percentage of metal adsorption and has the highest number of available sites for most of the metals studied. However, according to the results of the constant pH "Langmuirian" isotherm, Sphagnum sp. can be considered as the strongest adsorbent, although the relative difference from other mosses is within 20%. The LPM was found to satisfactorily fit the experimental data in the full range of the studied solution parameters. The results of this study demonstrate a rather similar pattern of five metal adsorptions on mosses, both as a function of pH and as a metal concentration, which is further corroborated by similar values of adsorption constants. Therefore, despite the species and geographic differences between the mosses, a universal adsorption edge and constant pH adsorption isotherm can be recommended for 4 studied mosses. The quantitative comparison of metal adsorption with other common natural organic and inorganic materials demonstrates

  13. Bifidobacterium breve with α-linolenic acid alters the composition, distribution and transcription factor activity associated with metabolism and absorption of fat

    PubMed Central

    Patterson, Elaine; Wall, Rebecca; Lisai, Sara; Ross, R. Paul; Dinan, Timothy G.; Cryan, John F.; Fitzgerald, Gerald F.; Banni, Sebastiano; Quigley, Eamonn M.; Shanahan, Fergus; Stanton, Catherine

    2017-01-01

    This study focused on the mechanisms that fatty acid conjugating strains - Bifidobacterium breve NCIMB 702258 and Bifidobacterium breve DPC 6330 - influence lipid metabolism when ingested with α-linolenic acid (ALA) enriched diet. Four groups of BALB/c mice received ALA enriched diet (3% (w/w)) either alone or in combination with B. breve NCIMB 702258 or B. breve DPC 6330 (109 CFU/day) or unsupplemented control diet for six weeks. The overall n-3 PUFA score was increased in all groups receiving the ALA enriched diet. Hepatic peroxisomal beta oxidation increased following supplementation of the ALA enriched diet with B. breve (P < 0.05) and so the ability of the strains to produce c9t11 conjugated linoleic acid (CLA) was identified in adipose tissue. Furthermore, a strain specific effect of B. breve NCIMB 702258 was found on the endocannabinoid system (ECS). Liver triglycerides (TAG) were reduced following ALA supplementation, compared with unsupplemented controls (P < 0.01) while intervention with B. breve further reduced liver TAG (P < 0.01), compared with the ALA enriched control. These data indicate that the interactions of the gut microbiota with fatty acid metabolism directly affect host health by modulating n-3 PUFA score and the ECS. PMID:28265110

  14. Adsorption Properties of Lignin-derived Activated Carbon Fibers (LACF)

    SciTech Connect

    Contescu, Cristian I.; Gallego, Nidia C.; Thibaud-Erkey, Catherine; Karra, Reddy

    2016-04-01

    The object of this CRADA project between Oak Ridge National Laboratory (ORNL) and United Technologies Research Center (UTRC) is the characterization of lignin-derived activated carbon fibers (LACF) and determination of their adsorption properties for volatile organic compounds (VOC). Carbon fibers from lignin raw materials were manufactured at Oak Ridge National Laboratory (ORNL) using the technology previously developed at ORNL. These fibers were physically activated at ORNL using various activation conditions, and their surface area and pore-size distribution were characterized by gas adsorption. Based on these properties, ORNL did down-select five differently activated LACF materials that were delivered to UTRC for measurement of VOC adsorption properties. UTRC used standard techniques based on breakthrough curves to measure and determine the adsorption properties of indoor air pollutants (IAP) - namely formaldehyde and carbon dioxide - and to verify the extent of saturated fiber regenerability by thermal treatments. The results are summarized as follows: (1) ORNL demonstrated that physical activation of lignin-derived carbon fibers can be tailored to obtain LACF with surface areas and pore size distributions matching the properties of activated carbon fibers obtained from more expensive, fossil-fuel precursors; (2) UTRC investigated the LACF potential for use in air cleaning applications currently pursued by UTRC, such as building ventilation, and demonstrated their regenerability for CO2 and formaldehyde, (3) Both partners agree that LACF have potential for possible use in air cleaning applications.

  15. Equilibrium models and kinetic for the adsorption of methylene blue on Co-hectorites.

    PubMed

    Ma, Jun; Jia, Yong-Zhong; Jing, Yan; Sun, Jin-He; Yao, Ying; Wang, Xiao-Hua

    2010-03-15

    The adsorption of methylene blue (MB) onto the surface of cobalt doping hectorite (Co-hectorite) was systematically studied. The physical properties of Co-hectorites were investigated, where characterizations were carried out by X-ray diffraction (XRD) and Electron Diffraction Spectrum (EDS) techniques, and morphology was examined by nitrogen adsorption. The sample with a Co content 5% (m/m) had a higher specific surface area than other Co-hectorites. The pore diameters were distributed between 2.5 and 5.0 nm. The adsorption results revealed that Co-hectorite surfaces possessed effective interactions with MB and bases, and greatest adsorption capacity achieved with Co content 5%, where the best-fit isotherm model was the Langmuir adsorption model. Kinetic studies were fitted to the pseudo-second-order kinetic model. The intraparticle diffusion was not the rate-limiting step for the whole reaction.

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

    NASA Astrophysics Data System (ADS)

    Sun, Baichuan; Chakraborty, Anutosh

    2014-05-01

    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.

  17. 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.

  18. Adsorption isotherms of charged nanoparticles.

    PubMed

    Dos Santos, Alexandre P; Bakhshandeh, Amin; Diehl, Alexandre; Levin, Yan

    2016-10-19

    We present theory and simulations which allow us to quantitatively calculate the amount of surface adsorption excess of charged nanoparticles onto a charged surface. The theory is very accurate for weakly charged nanoparticles and can be used at physiological concentrations of salt. We have also developed an efficient simulation algorithm which can be used for dilute suspensions of nanoparticles of any charge, even at very large salt concentrations. With the help of the new simulation method, we are able to efficiently calculate the adsorption isotherms of highly charged nanoparticles in suspensions containing multivalent ions, for which there are no accurate theoretical methods available.

  19. Thermodynamic features of dioxins' adsorption.

    PubMed

    Prisciandaro, Marina; Piemonte, Vincenzo; di Celso, Giuseppe Mazziotti; Ronconi, Silvia; Capocelli, Mauro

    2017-02-15

    In this paper, the six more poisonous species among all congeners of dioxin group are taken into account, and the P-T diagram for each of them is developed. Starting from the knowledge of vapour tensions and thermodynamic parameters, the theoretical adsorption isotherms are calculated according to the Langmuir's model. In particular, the Langmuir isotherm parameters (K and wmax) have been validated through the estimation of the adsorption heat (ΔHads), which varies in the range 20-24kJ/mol, in agreement with literature values. This result will allow to put the thermodynamical basis for a rational design of different process units devoted to dioxins removal.

  20. Counterion release and electrostatic adsorption

    PubMed

    Sens; Joanny

    2000-05-22

    The effective charge of a rigid polyelectrolyte (PE) approaching an oppositely charged surface is studied. The cases of a weak (annealed) and strongly charged PE with condensed counterions (such as DNA) are discussed. In the most interesting case of the adsorption onto a substrate of low dielectric constant (such as a lipid membrane or a mica sheet) the condensed counterions are not always released as the PE approaches the substrate, because of the major importance of the image-charge effect. For the adsorption onto a surface with freely moving charges, the image-charge effect becomes less important and full release is often expected.

  1. Metabolic acidosis.

    PubMed

    Lim, Salim

    2007-01-01

    Acute metabolic acidosis is frequently encountered in critically ill patients. Metabolic acidosis can occur as a result of either the accumulation of endogenous acids that consumes bicarbonate (high anion gap metabolic acidosis) or loss of bicarbonate from the gastrointestinal tract or the kidney (hyperchloremic or normal anion gap metabolic acidosis). The cause of high anion gap metabolic acidosis includes lactic acidosis, ketoacidosis, renal failure and intoxication with ethylene glycol, methanol, salicylate and less commonly with pyroglutamic acid (5-oxoproline), propylene glycole or djenkol bean (gjenkolism). The most common causes of hyperchloremic metabolic acidosis are gastrointestinal bicarbonate loss, renal tubular acidosis, drugs-induced hyperkalemia, early renal failure and administration of acids. The appropriate treatment of acute metabolic acidosis, in particular organic form of acidosis such as lactic acidosis, has been very controversial. The only effective treatment for organic acidosis is cessation of acid production via improvement of tissue oxygenation. Treatment of acute organic acidosis with sodium bicarbonate failed to reduce the morbidity and mortality despite improvement in acid-base parameters. Further studies are required to determine the optimal treatment strategies for acute metabolic acidosis.

  2. 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%).

  3. Metabolism of glyphosate in Sprague-Dawley rats: tissue distribution, identification, and quantitation of glyphosate-derived materials following a single oral dose.

    PubMed

    Brewster, D W; Warren, J; Hopkins, W E

    1991-07-01

    Five groups of male Sprague-Dawley rats were orally administered a mixture of [14C]- and [12C]-glyphosate (N-phosphonomethylglycine) at a dose level of 10 mg/kg body weight. The majority of radioactivity 2 hr after administration was associated with the gastrointestinal contents and small intestinal tissue. Approximately 35-40% of the administered dose was absorbed from the gastrointestinal tract, and urine and feces were equally important routes of elimination. The total body burden 7 days after administration was approximately 1% of the administered dose and was primarily associated with the bone. Total recovery for this study ranged from 95 to 102% of the administered dose. Metabolic profiles of tissues containing greater than 1% of the administered dose at various times after administration indicated that nearly 100% of the body burden of radioactivity was present as unmetabolized parent glyphosate. A minor component constituting less than 0.1% of the administered dose (less than 0.4 ppm) was observed in colon tissue from animals 2 hr after the administration of glyphosate and was also present in the GI contents of one animal 28 hr after administration of the radiolabel. The retention time for this metabolite was similar, but not identical, to the retention time for AMPA (aminomethylphosphonic acid), the major bacterial metabolite of glyphosate found in soil. Tissue extraction efficiency was always greater than 90% and stability assays indicated no significant effect of storage on either parent glyphosate or AMPA. The results from this study indicate that virtually no toxic metabolites of glyphosate were produced since there was little evidence of metabolism and essentially 100% of the body burden was parent compound with no significant persistence of material.

  4. 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.

  5. 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)

  6. 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...

  7. Aberrant expression and distribution of enzymes of the urea cycle and other ammonia metabolizing pathways in dogs with congenital portosystemic shunts.

    PubMed

    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.

  8. Structural characteristics of activated carbons and ibuprofen adsorption affected by bovine serum albumin.

    PubMed

    Melillo, M; Gun'ko, V M; Tennison, S R; Mikhalovska, L I; Phillips, G J; Davies, J G; Lloyd, A W; Kozynchenko, O P; Malik, D J; Streat, M; Mikhalovsky, S V

    2004-03-30

    Structural characteristics of a series of MAST carbons were studied using scanning electron microscopy images and the nitrogen adsorption isotherms analyzed with several models of pores and different adsorption equations. A developed model of pores as a mixture of gaps between spherical nanoparticles and slitlike pores was found appropriate for MAST carbons. Adsorption of ibuprofen [2-(4-isobutylphenyl)propionic acid] on activated carbons possessing different pore size distributions in protein-free and bovine serum albumin (BSA)-containing aqueous solutions reveals the importance of the contribution of mesopores to the total porosity of adsorbents. The influence of the mesoporosity increases when considering the removal of the drug from the protein-containing solution. Cellulose-coated microporous carbon Norit RBX adsorbs significantly smaller amounts of ibuprofen than uncoated micro/mesoporous MAST carbons whose adsorption capability increases with increasing mesoporosity and specific surface area, burnoff dependent variable. A similar effect of broad pores is observed on adsorption of fibrinogen on the same carbons. Analysis of the ibuprofen adsorption data using Langmuir and D'Arcy-Watt equations as the kernel of the Fredholm integral equation shows that the nonuniformity of ibuprofen adsorption complexes diminishes with the presence of BSA. This effect may be explained by a partial adsorption of ibuprofen onto protein molecules immobilized on carbon particles and blocking of a portion of narrow pores.

  9. Removal of the antibiotic metronidazole by adsorption on various carbon materials from aqueous phase.

    PubMed

    Carrales-Alvarado, D H; Ocampo-Pérez, R; Leyva-Ramos, R; Rivera-Utrilla, J

    2014-12-15

    The adsorption of the antibiotic metronidazole (MNZ) on activated carbon (F400), activated carbon cloth (ACF), mesoporous activated carbon (CMK-3), and carbon nanotubes (MWCNT) was investigated in this work. The effect of the adsorbent-adsorbate interactions as well as the operating conditions (ionic strength, solution pH, temperature, chemical modification of the adsorbents by HNO3 treatment, and water matrix) on the adsorption capacity were analyzed to substantiate the adsorption mechanism. The adsorption capacity markedly varied as function of the carbon material, decreasing in the following order: F400>ACF>F400-HNO3>CMK-3>MWCNT>MWCNT-HNO3, and depended not only on their surface area and pore size distribution, but also on their chemical nature. The adsorption of MNZ was influenced by the solution pH, but was not significantly affected by the ionic strength and temperature. The adsorption of MNZ was enhanced when the MNZ solutions were prepared using wastewater. Therefore, the electrolytes present in the wastewater cooperated rather than competed with the MNZ molecules for the adsorption sites. Desorption equilibrium data of MNZ on all carbon materials demonstrated that the adsorption was reversible corroborating the weakness of the adsorbent-adsorbate interactions.

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

    USGS Publications Warehouse

    DeBarr, Joseph A.; Lizzio, Anthony A.; Daley, Michael 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.

  11. 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

  12. 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...

  13. Adsorption of pesticides on resins.

    PubMed

    Kyriakopoulos, Grigorios; Hourdakis, Adamadia; Doulia, Danae

    2003-03-01

    The objective of this work was to assess the capability of organic hydrophobic polymeric resins Amberlite XAD-4 and XAD-7 to remove the pesticides alachlor and amitrole from water. The pesticides adsorption on the two different adsorbents was measured by batch equilibrium technique and isotherm types and parameters were estimated. Two theoretical models were applied based on a Freundlich and a Langmuir isotherms. The effect of pesticides chemical composition and structure as well as the nature of solid surface on the efficiency of adsorption was evaluated. The influence of pH also was studied. In low pH solutions adsorption of amitrole was higher upon the nonionic aliphatic acrylic ester copolymer XAD-7 in comparison to the nonionic, crosslinked macroreticular copolymer of styrene divinylbenzene XAD-4. In neutral and intermediate pH solutions the polar acrylic ester copolymer XAD-7 was more effective to the retention of alachlor. The acrylic ester copolymer showed at pH 3 the lower effectiveness in alachlor removal from water. The data of the adsorption isotherms of pesticides upon the examined polymeric resins seemed to conform to both the Freundlich and the Langmuir isotherm models.

  14. 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.

  15. Engineering and Design: Adsorption Design Guide

    DTIC Science & Technology

    2001-03-01

    adsorptive media addressed in- clude granular activated carbon (GAC) and other alternative adsorption carbon media, such as powdered activated carbon (PAC... Adsorption Media. a. Activated Carbon . Activated carbon can be manufactured from carbonaceous material, in- cluding coal (bituminous, subbituminous...information contained in Corps of Engineers Guide Specification 11225: Downflow Liquid Granular Activated Carbon

  16. 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.

  17. 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.

  18. Heterogeneous adsorption of activated carbon nanofibers synthesized by electrospinning polyacrylonitrile solution.

    PubMed

    Lee, Jae-Wook; Kang, Hyun-Chul; Shim, Wang-Geun; Kim, Chan; Yang, Kap-Seung; Moon, Hee

    2006-11-01

    This study focuses on the adsorption properties of activated carbon nanofibers (CNFs) fabricated by electrospinning polyacrylonitrile solutions dissolved in dimethylformamide, followed by heat treatment at high activation temperatures (700, 750, 800 degrees C). The samples were characterized by BET, SEM, and XRD. In addition, the adsorption energy distribution functions of CNFs were analyzed by using the generalized nonlinear regularization method. Comparative analysis of energy distribution functions provided significant information on the energetic and structural heterogeneities of CNFs. Furthermore, an investigation of adsorption equilibrium and kinetics of methylene blue (MB) and congo red (CR) revealed that the adsorption capacity and kinetics of MB are much higher and faster than that of CR on a given sample. Our experimental and theoretical results suggest that the CNFs used in this work may be widely used as an adsorbent.

  19. Study of Cs/NF3 adsorption on GaN (0 0 1) surface

    NASA Astrophysics Data System (ADS)

    Diao, Yu; Liu, Lei; Xia, Sihao; Kong, Yike

    2017-03-01

    To investigate the optoelectronics properties of Cs/NF3 adsorption on GaN (0 0 1) photocathode surface, different adsorption models of Cs-only, Cs/O, Cs/NF3 adsorption on GaN clean surface were established, respectively. Atomic structures, work function, adsorption energy, E-Mulliken charge distribution, density of states and optical properties of all these adsorption systems were calculated using first principles. Compared with Cs/O co-adsorption, Cs/NF3 co-adsorption show better stability and more decline of work function, which is more beneficial for photoemission efficiency. Besides, surface band structures of Cs/NF3 co-adsorption system exhibit metal properties, implying good conductivity. Meanwhile, near valence band minimum of Cs/NF3 co-adsorption system, more acceptor levels emerges to form a p-type emission surface, which is conductive to the escape of photoelectrons. In addition, imaginary part of dielectric function curve and absorption curve of Cs/NF3 co-adsorption system both move towards lower energy side. This work can direct the optimization of activation process of NEA GaN photocathode.

  20. 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.

  1. Characterization of micro-mesoporous materials from nitrogen and toluene adsorption: experiment and modeling.

    PubMed

    Ravikovitch, Peter I; Vishnyakov, Aleksey; Neimark, Alexander V; Ribeiro Carrott, Manuela M L; Russo, Patrícia A; Carrott, Peter J

    2006-01-17

    Universal mechanisms of adsorption and capillary condensation of toluene and nitrogen on ordered MCM-41 and PHTS materials are studied by means of high-resolution experiments and Monte Carlo molecular simulations. A molecular simulation model of toluene adsorption in silica nanopores, which accounts for surface heterogeneity, and a hybrid molecular-macsroscopic method for pore size distribution (PSD) calculations have been developed. For a range of reference materials, the PSD results obtained from toluene isotherms are consistent with the results of nitrogen adsorption using the nonlocal density functional theory method.

  2. From single molecules to water networks: Dynamics of water adsorption on Pt(111)

    NASA Astrophysics Data System (ADS)

    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.

  3. 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

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

    PubMed

    Stephens, Amanda M; Sanders, Timothy H

    2015-07-01

    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.

  5. Imaging metabolic syndrome

    PubMed Central

    Han, Weiping; Chuang, Kai-Hsiang; Chang, Young-Tae; Olivo, Malini; Velan, S Sendhil; Bhakoo, Kishore; Townsend, David; Radda, George K

    2010-01-01

    Metabolic syndrome is a fast growing public health burden for almost all the developed countries and many developing nations. Despite intense efforts from both biomedical and clinical scientists, many fundamental questions regarding its aetiology and development remain unclear, partly due to the lack of suitable imaging technologies to visualize lipid composition and distribution, insulin secretion, β-cell mass and functions in vivo. Such technologies would not only impact on our understanding of the complexity of metabolic disorders such as obesity and diabetes, but also aid in their diagnosis, drug development and assessment of treatment efficacy. In this article we discuss and propose several strategies for visualization of physiological and pathological changes that affect pancreas and adipose tissue as a result of the development of metabolic diseases. PMID:20533426

  6. Metabolic neuropathies

    MedlinePlus

    ... Severe infection throughout the body ( sepsis ) Thyroid disease Vitamin deficiencies (including vitamins B12 , B6 , E , and B1 ) Some ... best treatment is to correct the metabolic problem. Vitamin deficiencies are treated with diet or with vitamins by ...

  7. 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.

  8. 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.

  9. 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

  10. Adsorption modeling for macroscopic contaminant dispersal analysis

    SciTech Connect

    Axley, J.W.

    1990-05-01

    Two families of macroscopic adsorption models are formulated, based on fundamental principles of adsorption science and technology, that may be used for macroscopic (such as whole-building) contaminant dispersal analysis. The first family of adsorption models - the Equilibrium Adsorption (EA) Models - are based upon the simple requirement of equilibrium between adsorbent and room air. The second family - the Boundary Layer Diffusion Controlled Adsorption (BLDC) Models - add to the equilibrium requirement a boundary layer model for diffusion of the adsorbate from the room air to the adsorbent surface. Two members of each of these families are explicitly discussed, one based on the linear adsorption isotherm model and the other on the Langmuir model. The linear variants of each family are applied to model the adsorption dynamics of formaldehyde in gypsum wall board and compared to measured data.

  11. Simulation of methane adsorption on A-zeolites

    NASA Astrophysics Data System (ADS)

    Woestyn, A. M.; Mentasty, L.; Riccardo, J. L.; Zgrablich, G.

    1996-07-01

    A Monte Carlo simulation has been performed to study adsorption of CH4 on zeolites and the result are here presented for NaA and CaNaA zeolites. The adsorption isotherms of CH4 and the radial distribution of the adsorbed molecules have been obtained at four different temperatures in the pressure range 0 to 5 Mpa. The potential energy of adsorption has been calculated and the energy profile of a CH4 molecule along different axes in the zeolite cavity are discussed. High density storage of natural gas is essential for the efficient use of this gas as an alternative transportation fuel. One of the promising storage technologies is the adsorbed natural gas (ANG), in which the gas is adsorbed on highly microporous solids like zeolites or actived carbons. Structural as well as chemical properties of the porous adsorbents influence strongly the adsorption phenomenon, therefore, both experimental as theorical investigation are still necessary to select better solids for specific applications.

  12. Simulation of methane adsorption on A-zeolites

    SciTech Connect

    Woestyn, A.M.; Mentasty, L.; Riccardo, J.L.; Zgrablich, G.

    1996-07-01

    A Monte Carlo simulation has been performed to study adsorption of CH{sub 4} on zeolites and the result are here presented for NaA and CaNaA zeolites. The adsorption isotherms of CH{sub 4} and the radial distribution of the adsorbed molecules have been obtained at four different temperatures in the pressure range 0 to 5 Mpa. The potential energy of adsorption has been calculated and the energy profile of a CH{sub 4} molecule along different axes in the zeolite cavity are discussed. High density storage of natural gas is essential for the efficient use of this gas as an alternative transportation fuel. One of the promising storage technologies is the adsorbed natural gas (ANG), in which the gas is adsorbed on highly microporous solids like zeolites or actived carbons. Structural as well as chemical properties of the porous adsorbents influence strongly the adsorption phenomenon, therefore, both experimental as theorical investigation are still necessary to select better solids for specific applications. {copyright} {ital 1996 American Institute of Physics.}

  13. 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.

  14. 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

  15. Metabolic implications of menopause.

    PubMed

    Polotsky, Hanah N; Polotsky, Alex J

    2010-09-01

    The incidence of metabolic syndrome increases substantially during perimenopause and early menopause. Postmenopausal women are at a higher risk of hypertension, proatherogenic lipid changes, diabetes, and severe cardiovascular disease as compared with their premenopausal counterparts. Whether or not menopause has a causative contribution to the deteriorating metabolic profile that is independent of chronological aging has been a subject of many studies. Menopausal transition is associated with significant weight gain (2 to 2.5 kg over 3 years on average), which is not dissimilar to that in premenopausal women of like age. Concomitantly, there is an increase in abdominal adiposity and a decrease in energy expenditure, phenomena that have been postulated to explain the higher risk of metabolic syndrome and increases in cholesterol and triglycerides. Hypertension and diabetes become more prevalent with age and should be timely diagnosed and treated. Lifestyle changes including moderately decreased caloric intake and aerobic exercise could prevent proatherogenic changes and weight gain observed with aging. Accurate prediction of cardiovascular risk in midlife women is essential to help identify the subset of women who are likely to benefit from intensive management of metabolic risk factors. This review focuses on metabolic changes associated with menopausal transition, specifically alterations in weight, waist circumference, body fat distribution, energy expenditure, and circulating biomarkers including adipokines.

  16. 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.

  17. 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.

  18. 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.

  19. Hydrogen Adsorption in Carbon nanoparticles

    NASA Astrophysics Data System (ADS)

    Cabrera, A. L.; Rojas, S.; Dias-Droguett, D. E.; Bhuyan, H.; Aomoa, N.; Kakati, M.

    2013-03-01

    We have studied hydrogen adsorption in carbon nanoparticles using a quartz crystal microbalance. The carbon nanoparticles were synthesized from a thermal plasma jet at different pressure (15 - 263 torr) of the reactants and different current (50 - 250 A) to generate the plasma. The as-prepared carbon nanoparticles were directly deposited on top of the gold electrode of a quartz crystal and we monitored in-situ the changes in resonance frequency while the chamber was pressurized at different hydrogen pressures. These changes enabled determination of absorbed hydrogen mass in order to get H/C mass ratio curves as a function of H2 pressure. Adsorption curves obtained in some carbon nanoparticles indicated the formation of hydrogen monolayer inside the pores of the carbon nanoparticles. Using the value of the jump due to the formation of a H2\\ monolayer, a surface area was estimated between 40-60 m2/g for hydrogen adsorption. In other carbon samples, hydrogen uptake curves indicated that H2 was filling the sample's pores when pore volume was large. These observations will be discussed in detail for several carbon nanoparticles samples. Funds provided by VRI Puente 9/2012 and 10/2012

  20. 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

  1. 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

  2. Adsorption of Gemini surfactants onto clathrate hydrates.

    PubMed

    Salako, O; Lo, C; Couzis, A; Somasundaran, P; Lee, J W

    2013-12-15

    This work addresses the adsorption of two Gemini surfactants at the cyclopentane (CP) hydrate-water interface. The Gemini surfactants investigated here are Dowfax C6L and Dowfax 2A1 that have two anionic head groups and one hydrophobic tail group. The adsorption of these surfactants was quantified using adsorption isotherms and the adsorption isotherms were determined using liquid-liquid titrations. Even if the Gemini surfactant adsorption isotherms show multi-layer adsorption, they possess the first Langmuir layer with the second adsorption layer only evident in the 2A1 adsorption isotherm. Zeta potentials of CP hydrate particles in the surfactant solution of various concentrations of Dowfax C6L and Dowfax 2A1 were measured to further explain their adsorption behavior at the CP hydrate-water interface. Zeta potentials of alumina particles as a model particle system in different concentrations of sodium dodecyl sulfate (SDS), Dowfax C6L and Dowfax 2A1 were also measured to confirm the configuration of all the surfactants at the interface. The determination of the isotherms and zeta-potentials provides an understanding framework for the adsorption behavior of the two Gemini surfactants at the hydrate-water interface.

  3. Metabolism and tissue distribution of trace elements in broiler chickens' fed diets containing deficient and plethoric levels of copper, manganese, and zinc.

    PubMed

    Mondal, Sovik; Haldar, Sudipto; Saha, Pinaki; Ghosh, Tapan Kumar

    2010-11-01

    Supplementation of broiler diets with copper, manganese, and zinc at levels higher than that stipulated by the National Research Council 1994 reportedly improved live weight, feed conversion, and cured leg abnormality supposedly caused by inadequate intake of Mn and Zn. The objective of the study was to ascertain the effects of plethoric supplementation of copper (Cu), manganese (Mn), and zinc (Zn) on performance and metabolic responses in broiler chickens. The study also aimed to discriminate the responses of the birds when the mineral elements were supplemented either in an inorganic or in an organic form. Cobb 400 broiler chickens (1-day old, n = 300) were assigned to three dietary treatments each containing nine replicates with ten birds for 39 days. The treatments included a control in which the diet was devoid of supplemental trace elements and treatments supplemented with an inorganic trace element premix (ITM) and supplemented with a combination of the inorganic and an organic trace element premix (OTM). The ITM contained (per kilogram) copper, 15 g; iron, 90 g; manganese, 90 g; zinc, 80 g (all as sulfated salts); iodine (as potassium iodide), 2 g; and selenium (as sodium selenite), 0.3 g. The OTM on the other hand, contained copper, 2.5 g; iron, 15 g; manganese, 15 g; zinc, 13.33 g; and chromium, 0.226 g (all as protein chelates). Plethoric supplementation of trace elements improved live weight gain and feed/gain ratio (p < 0.05). Leg abnormality developed in the 16% of the control group of birds but not in the supplemented group. Metabolizability of dry matter, organic matter, and protein was higher (p < 0.01) in the ITM and OTM groups. Excretion of Cu, Fe, and Zn decreased (p < 0.1) due to supplementation of the trace elements leading to increased apparent absorption of the said mineral elements (p < 0.01). Concentration of the concerned trace elements in serum, liver, and composite muscle samples was higher (p < 0.05) in the ITM and OTM dietary groups

  4. Metabolism, distribution, and excretion of deoxynivalenol with combined techniques of radiotracing, high-performance liquid chromatography ion trap time-of-flight mass spectrometry, and online radiometric detection.

    PubMed

    Wan, Dan; Huang, Lingli; Pan, Yuanhu; Wu, Qinghua; Chen, Dongmei; Tao, Yanfei; Wang, Xu; Liu, Zhenli; Li, Juan; Wang, Liye; Yuan, Zonghui

    2014-01-08

    Dispositions of deoxynivalenol (DON) in rats and chickens were investigated, using a radiotracer method coupled with a novel γ-accurate radioisotope counting (γ-ARC) radio-high-performance liquid chromatography ion trap time-of-flight tandem mass spectrometry (radio-HPLC-IT-TOF-MS/MS) system. 3β-(3)H-DON was chemically synthesized and orally administrated to both sexes of rats and chickens as single or multiple doses. The results showed that DON was widely distributed and quickly eliminated in all tissues. The highest concentration was found in the gastrointestinal tract at 6 h post-administration. Substantially lower levels were detected in the kidney, liver, heart, lung, spleen, and brain. Three new metabolites were identified tentatively as 10-deoxynivalenol-sulfonate, 10-deepoxy-deoxynivalenol (DOM-1)-sulfonate, and deoxynivalenol-3α-sulfate. Deoxynivalenol-3α-sulfate was a major metabolite in chickens, while the major forms in rats were DOM-1 and DON. Additionally, a higher excretion rate in urine was observed in female rats than in male rats. The differences in metabolite profiles and excretion rates, which suggested diverse ways to detoxify, may relate to the different tolerances in different genders or species.

  5. Competitive adsorption of Pb and Cd on bacteria-montmorillonite composite.

    PubMed

    Du, Huihui; Chen, Wenli; Cai, Peng; Rong, Xingmin; Feng, Xionghan; Huang, Qiaoyun

    2016-11-01

    The characteristics and mechanisms of competitive adsorption of trace metals on bacteria-associated clay mineral composites have never been studied, despite their being among the most common organic-mineral complexes in geological systems. Herein, competitive adsorption of Pb and Cd on Pseudomonas putida-montmorillonite composite was investigated through adsorption-desorption experiment, isothermal titration calorimetry (ITC), and synchrotron micro X-ray fluorescence (μ-XRF). From the experiment, stronger competition was observed on clay mineral than on bacteria-clay composite because more non-specific sites accounted for heavy metal adsorption on clay mineral surface at the studied pH 5. Both competing heavy metals tended to react with bacterial fractions in the composite, which was verified by the higher correlation of Cd (and Pb) with Zn (R(2) = 0.41) elemental distribution than with Si (R(2) = 0.10). ITC results showed that competitive adsorption exhibited a lower entropy change (ΔS) at the metal-sorbent interfaces compared with single-metal adsorption, revealing that Cd and Pb are bound to the same types of adsorption sites on the sorbent. The competitive effect on bacteria-clay composite was found to be helpful for a better understanding on the fixation, remobilization and subsequent migration of heavy metals in multi-metal contaminated environments.

  6. First principles derived, transferable force fields for CO2 adsorption in Na-exchanged cationic zeolites.

    PubMed

    Fang, Hanjun; Kamakoti, Preeti; Ravikovitch, Peter I; Aronson, Matthew; Paur, Charanjit; Sholl, David S

    2013-08-21

    The development of accurate force fields is vital for predicting adsorption in porous materials. Previously, we introduced a first principles-based transferable force field for CO2 adsorption in siliceous zeolites (Fang et al., J. Phys. Chem. C, 2012, 116, 10692). In this study, we extend our approach to CO2 adsorption in cationic zeolites which possess more complex structures. Na-exchanged zeolites are chosen for demonstrating the approach. These methods account for several structural complexities including Al distribution, cation positions and cation mobility, all of which are important for predicting adsorption. The simulation results are validated with high-resolution experimental measurements of isotherms and microcalorimetric heats of adsorption on well-characterized materials. The choice of first-principles method has a significant influence on the ability of force fields to accurately describe CO2-zeolite interactions. The PBE-D2 derived force field, which performed well for CO2 adsorption in siliceous zeolites, does not do so for Na-exchanged zeolites; the PBE-D2 method overestimates CO2 adsorption energies on multi-cation sites that are common in cationic zeolites with low Si/Al ratios. In contrast, a force field derived from the DFT/CC method performed well. Agreement was obtained between simulation and experiment not only for LTA-4A on which the force field fitting is based, but for other two common adsorbents, NaX and NaY.

  7. 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

    2014-12-02

    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.

  8. Adsorption characteristics of Orange II and Chrysophenine on sludge adsorbent and activated carbon fibers.

    PubMed

    Hsiu-Mei, Chiang; Ting-Chien, Chen; San-De, Pan; Chiang, Hung-Lung

    2009-01-30

    Sludge adsorbent (SA) and commercial activated carbon fibers (ACFC and ACFT) were applied to Orange II and Chrysophenine (CH) adsorption (BET surface area: ACFC>ACFT>SA). ACFT was primarily in the micropore range, while SA was approximately 500 A (macropore) and 80 A (mesopore). The ACFC pore volume was high in both the mesopore and micropore regions. Measurement of the oxygen surface functional groups of the adsorbents using Boehm's titration method showed a similar distribution on the carbon fibers (mainly in the carbonyl group), while SA was mainly in the carboxyl, lactone and phenolic groups. The SA, ACFC and ACFT adsorption capacities of Orange II (30-80 mg/l) ranged from 83 to 270, 209-438, and 25-185 mg/g at temperatures ranging from 10 to 60 degrees C, respectively. CH concentration ranged from 30 to 80 mg/l, corresponding to SA and ACFC adsorption capacities of 39-191 and 48-374 mg/g over the defined temperature range, from 10 to 60 degrees C. CH adsorption on ACFT was low. The adsorption capacity of Orange II on ACFT was lower than on SA at 10 degrees C, but at higher temperatures the Orange II molecules were transported into the ACFT, producing an adsorption capacity similar to that of SA. Mass transfer increased with temperature, overcoming the adsorption energy barrier. Overall, SA and ACFC were more effective than ACFT.

  9. 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.

  10. Temperature-dependent adsorption of hydrogen, deuterium, and neon on porous Vycor glass

    NASA Astrophysics Data System (ADS)

    Huber, T. E.; Scardino, D.; Tsou, H. L.

    1995-10-01

    Adsorption isotherms of H2, D2, and Ne have been measured in the temperature range from 15 K to the corresponding critical points in samples of porous Vycor glass. From the Brunauer-Emmett-Teller theory the surface layer coverages are determined. These are found to be temperature dependent. A model-independent approach allows us to fit the data for coverages ranging from submonolayer to thin film, below capillary condensation, for each adsorbate at all temperatures with a temperature-independent curve. This characteristic curve represents the distribution of adsorption sites versus the adsorption potential. In the intermediate coverage range, the isotherms exhibit the modified Frenkel-Halsey-Hill (FHH) behavior. The adsorption saturates for low-adsorption potentials. The characteristic curve is a useful universal curve since it is roughly the same for the three species investigated. We examine the relative strengths of the surface potentials and densities of the two isotopic modifications of hydrogen and of the more classical Ne adsorbed on porous Vycor glass. The characteristic adsorption curve is compared with results from two models for the adsorbate: Dubinin's isotherm for microporous solids and its extension to rough surfaces which places importance on the porosity of the surface, and Halsey's model, which is an extension of the FHH isotherm that takes into account the long-range variations of substrate adsorption potential.

  11. Adsorption of pharmaceuticals to microporous activated carbon treated with potassium hydroxide, carbon dioxide, and steam.

    PubMed

    Fu, Heyun; Yang, Liuyan; Wan, Yuqiu; Xu, Zhaoyi; Zhu, Dongqiang

    2011-01-01

    Adsorption of sulfapyridine, tetracycline, and tylosin to a commercial microporous activated carbon (AC) and its potassium hydroxide (KOH)-, CO-, and steam-treated counterparts (prepared by heating at 850°C) was studied to explore efficient adsorbents for the removal of selected pharmaceuticals from water. Phenol and nitrobenzene were included as additional adsorbates, and nonporous graphite was included as a model adsorbent. The activation treatments markedly increased the specific surface area and enlarged the pore sizes of the mesopores of AC (with the strongest effects shown on the KOH-treated AC). Adsorption of large-size tetracycline and tylosin was greatly enhanced, especially for the KOH-treated AC (more than one order of magnitude), probably due to the alleviated size-exclusion effect. However, the treatments had little effect on adsorption of low-size phenol and nitrobenzene due to the predominance of micropore-filling effect in adsorption and the nearly unaffected content of small micropores causative to such effect. These hypothesized mechanisms on pore-size dependent adsorption were further tested by comparing surface area-normalized adsorption data and adsorbent pore size distributions with and without the presence of adsorbed antibiotics. The findings indicate that efficient adsorption of bulky pharmaceuticals to AC can be achieved by enlarging the adsorbent pore size through suitable activation treatments.

  12. Interfacial Adsorption of Antifreeze Proteins: A Neutron Reflection Study

    PubMed Central

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

    2008-01-01

    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 SiO2 substrate. The layer thickness of 32 Å 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 Å. 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

  13. Granular bamboo-derived activated carbon for high CO(2) adsorption: the dominant role of narrow micropores.

    PubMed

    Wei, Haoran; Deng, Shubo; Hu, Bingyin; Chen, Zhenhe; Wang, Bin; Huang, Jun; Yu, Gang

    2012-12-01

    Cost-effective biomass-derived activated carbons with a high CO(2) adsorption capacity are attractive for carbon capture. Bamboo was found to be a suitable precursor for activated carbon preparation through KOH activation. The bamboo size in the range of 10-200 mesh had little effect on CO(2) adsorption, whereas the KOH/C mass ratio and activation temperature had a significant impact on CO(2) adsorption. The bamboo-derived activated carbon had a high adsorption capacity and excellent selectivity for CO(2) , and also the adsorption process was highly reversible. The adsorbed amount of CO(2) on the granular activated carbon was up to 7.0 mmol g(-1) at 273 K and 1 bar, which was higher than almost all carbon materials. The pore characteristics of activated carbons responsible for high CO(2) adsorption were fully investigated. Based on the analysis of narrow micropore size distribution of several activated carbons prepared under different conditions, a more accurate micropore range contributing to CO(2) adsorption was proposed. The volume of micropores in the range of 0.33-0.82 nm had a good linear relationship with CO(2) adsorption at 273 K and 1 bar, and the narrow micropores of about 0.55 nm produced the major contribution, which could be used to evaluate CO(2) adsorption on activated carbons.

  14. 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.

  15. [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.

  16. Adsorption of tetracycline on soil and sediment: effects of pH and the presence of Cu(II).

    PubMed

    Zhang, Zheyun; Sun, Ke; Gao, Bo; Zhang, Guixiang; Liu, Xitao; Zhao, Ye

    2011-06-15

    Tetracycline (TC) is frequently detected in the environment, however, knowledge on the environmental fate and transport of TC is still limited. Batch adsorption experiments of TC by soil and sediment samples were conducted. The distribution of charge and electrostatic potential of individual atoms of various TC species in the aqueous solution were determined using MOPAC version 0.034 W program in ChemBio3D Ultra software. Most of the adsorption isotherms on the soil, river and marine sediments were well fitted with the Freundlich and Polanyi-Manes (PMM) models. The single point organic carbon (OC)-normalized adsorption distribution coefficients (K(OC)) and PMM saturated adsorption capacity (Q(OC)(0)) values of TC were associated with the mesopore volume and clay content to a greater extent, indicating the mesopore volume of the soil and sediments and their clay content possibly influenced the fate and transport of TC in the natural environment. The adsorption of TC on soil and sediments strongly depended on the pH and presence of Cu(II). The presence of Cu(II) facilitated TC adsorption on soil and sediments at low pH (pH<5), possibly due to the metallic complexation and surface-bridging mechanism by Cu(II) adsorption on soil and sediments. The cation exchange interaction, metallic complexation and Coulombic interaction of mechanisms for adsorption of TC to soils and sediments were further supported by quantum chemical calculation of various TC species in different pH.

  17. 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

  18. DNA stickers promote polymer adsorption onto cellulose.

    PubMed

    Sato, Teruaki; Ali, Md Monsur; Pelton, Robert; Cranston, Emily D

    2012-10-08

    Adsorption of oligonucleotides onto model cellulose surfaces was investigated by comparing the Boese and Breaker's cellulose binding oligonucleotide (CBO) with a nonspecific oligonucleotide control (NSO). Measurements using the quartz crystal microbalance with dissipation technique confirmed that CBO adsorbed onto cellulose more than NSO, particularly at high ionic strengths (100 mM CaCl(2)). CBO showed a higher maximum adsorption on nanofibrillated and nanocrystalline cellulose than on regenerated cellulose, indicating a preference for the native cellulose I crystal structure under conditions that favored specific adsorption over calcium-mediated electrostatically driven adsorption. In addition, an anionic polyacrylamide (A-PAM) with grafted CBO also adsorbed onto the surface of cellulose in CaCl(2), whereas the unmodified A-PAM did not. This work shows that CBO performs as a "sticker", facilitating the adsorption of polyacrylamide onto cellulose, even under high ionic strength conditions where the adsorption of conventional polyelectrolytes is inhibited.

  19. 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.

  20. Enhanced adsorption of humic acids on ordered mesoporous carbon compared with microporous activated carbon.

    PubMed

    Liu, Fengling; Xu, Zhaoyi; Wan, Haiqin; Wan, Yuqiu; Zheng, Shourong; Zhu, Dongqiang

    2011-04-01

    Humic acids are ubiquitous in surface and underground waters and may pose potential risk to human health when present in drinking water sources. In this study, ordered mesoporous carbon was synthesized by means of a hard template method and further characterized by X-ray diffraction, N2 adsorption, transition electron microscopy, elemental analysis, and zeta-potential measurement. Batch experiments were conducted to evaluate adsorption of two humic acids from coal and soil, respectively, on the synthesized carbon. For comparison, a commercial microporous activated carbon and nonporous graphite were included as additional adsorbents; moreover, phenol was adopted as a small probe adsorbate. Pore size distribution characterization showed that the synthesized carbon had ordered mesoporous structure, whereas the activated carbon was composed mainly of micropores with a much broader pore size distribution. Accordingly, adsorption of the two humic acids was substantially lower on the activated carbon than on the synthesized carbon, because of the size-exclusion effect. In contrast, the synthesized carbon and activated carbon showed comparable adsorption for phenol when the size-exclusion effect was not in operation. Additionally, we verified by size-exclusion chromatography studies that the synthesized carbon exhibited greater adsorption for the large humic acid fraction than the activated carbon. The pH dependence of adsorption on the three carbonaceous adsorbents was also compared between the two test humic acids. The findings highlight the potential of using ordered mesoporous carbon as a superior adsorbent for the removal of humic acids.

  1. 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.

  2. Electrophoretic Mobility Study of the Adsorption of Alkyl Xanthate Ions on Galena and Sphalerite.

    PubMed

    Song, S.; Lopez-Valdivieso, A.; Ojeda-Escamilla, M. C.

    2001-05-01

    The adsorption of ethyl and amyl xanthate ions on galena and sphalerite fines has been studied using electrophoretic light-scattering (ELS) measurements. It was performed on galena and sphalerite (<2&mgr;m) in aqueous solution at different potassium ethyl xanthate (PEX) and potassium amyl xanthate (PAX) concentrations. It has been observed that the presence of PEX or PAX caused the isoelectric points (IEP) of galena and sphalerite fines to shift and the electrophoretic mobility to reverse in sign, indicating that the xanthate ions chemisorbed on galena and sphalerite surfaces. This adsorption markedly broadened the electrophoretic mobility distribution of the mineral fines, suggesting that the populations of the particles have quite different adsorption densities of xanthate ions, and therefore the particle hydrophobicity was different. This phenomenon might be attributable to the effect of the hemimicelle adsorption of the xanthate ions on the minerals, the nonuniform distribution of active sites and their degree of activity, the effect of particle size and shape, etc. The nonuniform adsorption has been found to increase with increasing PEX or PAX concentration, reaching a maximum at a medium concentration followed by a decline. Also, experimental results have demonstrated that the nonuniform adsorption of the xanthate ions is much stronger on sphalerite than on galena, which may explain why sphalerite has a worse flotation response than galena when alkyl xanthates are used as collectors in flotation systems. Copyright 2001 Academic Press.

  3. 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

  4. IgG adsorption on a new protein A adsorbent based on macroporous hydrophilic polymers. I. Adsorption equilibrium and kinetics.

    PubMed

    Perez-Almodovar, Ernie X; Carta, Giorgio

    2009-11-20

    Experimental determination and modeling of IgG binding on a new protein A adsorbent based on a macroporous resin were performed. The new adsorbent consists of polymeric beads based on hydrophilic acrylamido and vinyl monomers with a pore structure optimized to allow favorable interactions of IgG with recombinant protein A coupled to the resin. The particles have average diameter of 57 microm and a narrow particle size distribution. The IgG adsorption equilibrium capacity is 46 mg/cm(3) and the effective pore diffusivity determined from pulse response experiments for non-binding conditions is 8.0 x 10(-8) cm(2)/s. The IgG adsorption kinetics can be described with the same effective diffusivity by taking into account a heterogeneous binding mechanism with fast binding sites, for which adsorption is completely diffusion controlled, and slow binding sites for which adsorption is controlled by the binding kinetics. As a result of this mechanism, the breakthrough curve exhibits a tailing behavior, which appears to be associated with the slow binding sites. A detailed rate model taking into account intraparticle diffusion and binding kinetics is developed and is found capable of predicting both batch adsorption and breakthrough behavior over an ample range of experimental conditions. The corresponding effective diffusivity is independent of protein concentration in solution over the range 0.2-2 mg/cm(3) and of protein binding as a result of the large pore size of the support matrix. Overall, the small particle size and low diffusional hindrance allow capture of IgG with short residence times while attaining substantial dynamic binding capacities.

  5. Molecular diffusion between walls with adsorption and desorption

    NASA Astrophysics Data System (ADS)

    Levesque, Maximilien; Bénichou, Olivier; Rotenberg, Benjamin

    2013-01-01

    The time dependency of the diffusion coefficient of particles in porous media is an efficient probe of their geometry. The analysis of this quantity, measured, e.g., by nuclear magnetic resonance, can provide rich information pertaining to porosity, pore size distribution, permeability, and surface-to-volume ratio of porous materials. Nevertheless, in numerous if not all practical situations, transport is confined by walls where adsorption and desorption processes may occur. In this article, we derive explicitly the expression of the time-dependent diffusion coefficient between two confining walls in the presence of adsorption and desorption. We show that they strongly modify the time-dependency of the diffusion coefficient, even in this simple geometry. We finally propose several applications, from sorption rates measurements to the use as a reference for numerical implementations for more complex geometries.

  6. Structural characteristics of modified activated carbons and adsorption of explosives.

    PubMed

    Tomaszewski, W; Gun'ko, V M; Skubiszewska-Zieba, J; Leboda, R

    2003-10-15

    Several series of activated carbons prepared by catalytic and noncatalytic gasification and subsequent deposition of pyrocarbon by pyrolysis of methylene chloride or n-amyl alcohol were studied by FTIR, chromatography, and adsorption methods using nitrogen and probe organics (explosives). The relationships between the textural characteristics of carbon samples and the recovery rates (eta) of explosives on solid-phase extraction (SPE) using different solvents for their elution after adsorption were analyzed using experimental and quantum chemical calculation results. The eta values for nitrate esters, cyclic nitroamines, and nitroaromatics only partially correlate with different adsorbent parameters (characterizing microporosity, mesoporosity, pore size distributions, etc.), polarity of eluting solvents, or characteristics of probe molecules, since there are many factors strongly affecting the recovery rates. Some of the synthesized carbons provide higher eta values than those for such commercial adsorbents as Hypercarb and Envicarb.

  7. 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.

  8. Acid natural clinoptilolite: structural properties against adsorption/separation of n-paraffins.

    PubMed

    Rivera, Aramis; Farías, Tania; de Ménorval, Louis Charles; Autié-Castro, Giselle; Yee-Madeira, Hernany; Contreras, José Luis; Autié-Pérez, Miguel

    2011-08-01

    The employment of an acid natural clinoptilolite (AZH-1) in the adsorption and separation of n-paraffins has been evaluated. Natural clinoptilolite, NZ, was the raw material used to prepare the sodium-exchanged clinoptilolite (AZ) starting from which the AZH-1 sample was obtained by acid treatment. The structural stability of the samples after the applied treatments was demonstrated. The nitrogen adsorption experiments indicated that the acid sample has a homogeneous porous distribution and a considerable increase in the micropore volume with respect to NZ and AZ. The employment of the inverse gas chromatography at infinite dilution (IGCID) allowed studying the adsorption and separation of n-paraffin mixtures on AZH-1. It was also confirmed that the diffusion on AZH-1 took place in an unblocked structure through the A channel of ten members with minimal interactions. The IGCID results demonstrated the capacities of the acid Cuban natural zeolite in the adsorption and separation of n-paraffin mixtures.

  9. Adsorption of Pb(II) from aqueous solution by a poly-elemental mesoporous adsorbent

    NASA Astrophysics Data System (ADS)

    Wu, Xiu-Wen; Ma, Hong-Wen; Yang, Jing; Wang, Feng-Jiao; Li, Zhi-Hong

    2012-05-01

    A poly-elemental mesoporous adsorbent was hydrothermally prepared from microcline in an alkaline condition with cetyltrimethylammonium bromide as synthesis directing agent. The properties of the mesoporous adsorbent were determined by X-ray powder diffraction, high-resolution transmission electron microscope, N2 adsorption, and solid-state Magic Angle Spinning Nuclear Magnetic Resonance. The pore size distribution was detected by small angle X-ray scattering. The particles size was observed by Scanning electron microscope imagine. The chemical content of SiO2 in the mesoporous adsorbent was determined by spectrometry of the silicone molybdenum and sulfosalicylic acid complexes, and Al2O3 determined by complexometry with ethylene diamine tetraacetic acid in the presence of KF-Zn(Ac)2 tests. The adsorption properties of the mesoporous adsorbent to Pb(II) were studied, and three main factors, the adsorption time, solution pH, and initial concentration of Pb(II), were considered in the adsorption experiments.

  10. Heterogeneity of activated carbons in adsorption of aniline from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Podkościelny, P.; László, K.

    2007-08-01

    The heterogeneity of activated carbons (ACs) prepared from different precursors is investigated on the basis of adsorption isotherms of aniline from dilute aqueous solutions at various pH values. The APET carbon prepared from polyethyleneterephthalate (PET), as well as, commercial ACP carbon prepared from peat were used. Besides, to investigate the influence of carbon surface chemistry, the adsorption was studied on modified carbons based on ACP carbon. Its various oxygen surface groups were changed by both nitric acid and thermal treatments. The Dubinin-Astakhov (DA) equation and Langmuir-Freundlich (LF) one have been used to model the phenomenon of aniline adsorption from aqueous solutions on heterogeneous carbon surfaces. Adsorption-energy distribution (AED) functions have been calculated by using an algorithm based on a regularization method. Analysis of these functions for activated carbons studied provides important comparative information about their surface heterogeneity.

  11. 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.

  12. 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.

  13. Adsorption-desorption properties and characterization of crosslinked Konjac glucomannan-graft-polyacrylamide-co-sodium xanthate.

    PubMed

    Wang, Lu-Feng; Duan, Jia-Cai; Miao, Wen-Hua; Zhang, Ruo-Jie; Pan, Si-Yi; Xu, Xiao-Yun

    2011-02-28

    A new flocculant, based on Konjac-graft-poly (acrylamide)-co-sodium xanthate (CKAX), was synthesized in aqueous solution using epichlorohydrin (ECH) as the cross-linker and ceric ammonium nitrate (CAN) as the initiator. X-ray diffraction indicated the existence of strong interaction between KGM and reactant, including intermolecular and intramolecular hydrogen bonds. Microscopy images exhibited the appropriate pore size and distribution, which might be related to a higher capacity of flocculation and adsorption. Thermo gravimetric analysis showed that the synthetic polymer could improve the thermo-stability of the natural polysaccharides, and there was a positive correlation between polymer residual weight and flocculation. The adsorption and desorption properties for copper ions indicated that the adsorption rate could be described by a pseudo-second-order rate model, and the Freundlich model provides the best fit for the resulting adsorption isotherm. The flocculant can be regenerated in HNO(3) solution.

  14. 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.

  15. Metabolic Disorders

    MedlinePlus

    ... affect the breakdown of amino acids, carbohydrates, or lipids. Another group, mitochondrial diseases, affects the parts of the cells that produce the energy. You can develop a metabolic disorder when some organs, such as your liver or pancreas, become diseased or do not function ...

  16. Metabolic Syndrome

    MedlinePlus

    Metabolic syndrome is a group of conditions that put you at risk for heart disease and diabetes. These conditions are High blood pressure High blood glucose, or blood sugar, levels High levels of triglycerides, a type of fat, in your blood Low levels ...

  17. 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.

  18. 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.

  19. Adsorption of acid dye onto organobentonite.

    PubMed

    Baskaralingam, P; Pulikesi, M; Elango, D; Ramamurthi, V; Sivanesan, S

    2006-02-06

    Removal of Acid Red 151 from aqueous solution at different dye concentrations, adsorbent doses and pH has been studied. The bentonite clay has been modified using cationic surfactants, which has been confirmed using XRD and FT-IR analyses. Experimental result has shown that the acidic pH favours the adsorption. The adsorption isotherms are described by means of Langmuir and Freundlich isotherms. The adsorption capacity has been found to be 357.14 and 416.66 mg g(-1) for the cetyldimethylbenzylammonium chloride-bentonite (CDBA-bent) and cetylpyridinium chloride-bentonite (CP-bent), respectively. Kinetic studies show that the adsorption followed second-order kinetics.

  20. 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

  1. Adsorption-desorption reactions of selenium (VI) in tropical cultivated and uncultivated soils under Cerrado biome.

    PubMed

    Lessa, J H L; Araujo, A M; Silva, G N T; Guilherme, L R G; Lopes, G

    2016-12-01

    Soil management may affect selenium (Se) adsorption capacity. This study investigated adsorption and desorption of Se (VI) in selected Brazilian soils from the Cerrado biome, an area of ever increasing importance for agriculture expansion in Brazil. Soil samples were collected from cultivated and uncultivated soils, comprising clayed and sandy soils. Following chemical and mineralogical characterization, soil samples were subjected to Se adsorption and desorption tests. Adsorption was evaluated after a 72-h reaction with increasing concentrations of Se (0-2000 μg L(-1)) added as Na2SeO4 in a NaCl electrolyte solution (pH 5.5; ionic strength 15 mmol L(-1)). Desorption, as well as distribution coefficients (Kd) for selenate were also assessed. Soil management affected Se adsorption capacity, i.e., Se adsorbed amounts were higher for uncultivated soils, when compared to cultivated ones. Such results were also supported by data of Kd and maximum adsorption capacity of Se. This fact was attributed mainly to the presence of greater amounts of competing anions, especially phosphate, in cultivated soils, due to fertilizer application. Phosphate may compete with selenate for adsorption sites, decreasing Se retention. For the same group of soils (cultivated and uncultivated), Se adsorption was greater in the clayed soils compared to sandy ones. Our results support the idea that adding Se (VI) to the soil is a good strategy to increase Se levels in food crops (agronomic biofortification), especially when crops are grown in soils that have been cultivated over the time due to their low Se adsorption capacity (high Se availability).

  2. 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...

  3. Glucose oxidase adsorption performance of carbonaceous mesocellular foams prepared with different carbon sources.

    PubMed

    Zhou, Fengjiao; Pu, Ximing; Luo, Dapeng; Yin, Guangfu; Zhuang, Kai; Liao, Xiaoming; Huang, Zhongbin; Chen, Xianchun; Yao, Yadong

    2015-07-01

    Several carbonaceous mesocellular foams (C-MCFs) were prepared with MCF-silica as template using the carbon precursors of sucrose, furfuryl alcohol and lab-made phenolic resin, and the corresponding C-MCFs were named as C-MCF-Suc, C-MCF-FA and C-MCF-PR, respectively. The results of SEM, transmission electron microscopy, N2 adsorption-desorption and energy-dispersive X-ray measurements indicated that the C-MCFs prepared from different carbon source appeared morphologically with different degree of order and different pore distribution. The C-MCF-FA exhibited the highest ordered structure and the smallest pore distribution among the foams. The optimum conditions for adsorption of C-MCFs on glucose oxidase (GOD) were also studied, and the maximum adsorbance was determined. The adsorption of GOD on C-MCF-FA was performed at different pH with different GOD concentrations. The maximum adsorption (423.3 mg g(-1)) was observed near the isoelectric point of the GOD (pI ≈ 5.0) with a GOD concentration of 6.0 mg mL(-1), suggesting that the GOD adsorption on C-MCFs might be affected strongly by the electric repulsion between the GOD molecules. Moreover, GOD adsorption performances on different C-MCFs revealed that both the pore size and the pore volume played important roles in the adsorption process, and the window size of C-MCFs dominated the residual immobilized amounts of GOD. Compared to the other two C-MCFs, the C-MCF-FA with a smaller window pore (10 nm) and higher volume (1.40 cm(3) g(-1)) exhibited the highest GOD adsorption and catalytic activity. Furthermore, the immobilized GOD exhibited improved thermal and storable stabilities. Thus the C-MCF-FA could be served as the prospective GOD carrier material used in enzymatic fuel cells.

  4. 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.

  5. Anion adsorption induced surface reconstructions

    NASA Astrophysics Data System (ADS)

    Tang, Lei

    2005-11-01

    Surface stress plays an important role in the behavior of solid surfaces. Potential-controlled anion adsorption in electrolytes alters the surface stress of the electrode and results in morphology changes to the surfaces. With a combination of potential-induced surface stress measurement and in situ electrochemical scanning tunneling microscopy (STM), it is demonstrated that anion adsorption induces changes in structure of thin films and modifies the growth morphology and stress evolution in epitaxially grown films. Surface structural transitions in the heteroepitaxial system consisting of one to two gold monolayers on platinum substrates were observed. By increasing the potential, structural transitions, from (1 x 1), to a striped phase, to a hexagonal structure, occurred in the gold bilayer. This hexagonal structure was related to the formation of an ordered sulfate adlayer with a ( 3x7 ) structure. Such transitions were repeatable by cycling the potential. Furthermore, the transitions between various dislocation structures were affected by anion adsorption. The surface composition of the gold bilayer on Pt was measured by underpotential deposition of copper. By subtracting the contribution of a pure Pt surface from the gold bi-layer on Pt, a stress change of -2.4 N/m was observed, which agrees with the stress change of -2.46 N/m predicted to accompany formation of 1.5 MLs of coherent Au on Pt(111) from epitaxy theory. The Cu monolayer deposited on Au(111) from an acid sulfate electrolyte was found to be pseudomorphic while the Cu monolayer formed on Au(111) in vacuum was incoherent. The stress-thickness change associated with the coherent monolayer of copper on Au(111) in electrolyte was -0.6 N/m, while conventional epitaxy theories predict a value of +7.76 N/m. STM results elucidated the sulfate adsorption on the copper monolayer caused an expansion of the layer as evidenced by a Moire Structure. For the Cu monolayer on Au(111), the sulfate-induced expansion

  6. 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.

  7. 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.

  8. Scaling Properties of the Number of Random Sequential Adsorption Iterations Needed to Generate Saturated Random Packing

    NASA Astrophysics Data System (ADS)

    Cieśla, Michał

    2017-01-01

    The properties of the number of iterations in random sequential adsorption protocol needed to generate finite saturated random packing of spherically symmetric shapes were studied. Numerical results obtained for one, two, and three dimensional packings were supported by analytical calculations valid for any dimension d. It has been shown that the number of iterations needed to generate finite saturated packing is subject to Pareto distribution with exponent -1-1/d and the median of this distribution scales with packing size according to the power-law characterized by exponent d. Obtained results can be used in designing effective random sequential adsorption simulations.

  9. CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Monomer Adsorption-Desorption Processes

    NASA Astrophysics Data System (ADS)

    Ke, Jian-Hong; Lin, Zhen-Quan; Chen, Xiao-Shuang

    2009-05-01

    We propose an adsorption-desorption model for a deposit growth system, in which the adsorption and desorption of particles coexist. By means of the generalized rate equation we investigate the cluster (island) size distribution in the dynamic equilibrium state. The results show that the evolution behaviour of the system depends crucially on the details of the rate kernels. The cluster size distribution can take the scale-free power-law form in some cases, while it grows exponentially with size in other cases.

  10. 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

  11. 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.

  12. Heterogeneity of activated carbons in adsorption of phenols from aqueous solutions—Comparison of experimental isotherm data and simulation predictions

    NASA Astrophysics Data System (ADS)

    Podkościelny, P.; Nieszporek, K.

    2007-01-01

    Surface heterogeneity of activated carbons is usually characterized by adsorption energy distribution (AED) functions which can be estimated from the experimental adsorption isotherms by inverting integral equation. The experimental data of phenol adsorption from aqueous solution on activated carbons prepared from polyacrylonitrile (PAN) and polyethylene terephthalate (PET) have been taken from literature. AED functions for phenol adsorption, generated by application of regularization method have been verified. The Grand Canonical Monte Carlo (GCMC) simulation technique has been used as verification tool. The definitive stage of verification was comparison of experimental adsorption data and those obtained by utilization GCMC simulations. Necessary information for performing of simulations has been provided by parameters of AED functions calculated by regularization method.

  13. [Homocysteine metabolism].

    PubMed

    Hashimoto, Takao; Shinohara, Yoshihiko; Hasegawa, Hiroshi

    2007-10-01

    Homocysteine, a sulfur amino acid, is an intermediate metabolite of methionine. In 1969, McCully reported autopsy evidence of extensive arterial thrombosis and atherosclerosis in children with elevated plasma homocysteine concentrations and homocystinuria. On the basis of this observation, he proposed that elevated plasma homocysteine (hyperhomocysteinemia) can cause atherosclerotic vascular disease. Hyperhomocysteinemia is now well established as an independent risk factor for atherosclerotic vascular disease. Mild hyperhomocysteinemia is quite prevalent in the general population. It can be caused by genetic defects in the enzymes involved in homocysteine metabolism or nutritional deficiencies in vitamin cofactors, certain medications or renal disease. An increase of 5 micromol per liter in the plasma homocysteine concentration raises the risk of coronary artery disease by as much as an increase of 20 mg per deciliter in the cholesterol concentration. In this article, we review the biochemical, experimental and clinical studies on hyperhomocysteinemia, with emphasis on the metabolism and pharmacokinetics of homocysteine.

  14. What is Metabolic Syndrome?

    MedlinePlus

    ... from the NHLBI on Twitter. What Is Metabolic Syndrome? Metabolic syndrome is the name for a group of ... that may play a role in causing metabolic syndrome. Outlook Metabolic syndrome is becoming more common due to a ...

  15. 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

  16. 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.

  17. Adsorption of beta blockers to environmental surfaces.

    PubMed

    Kibbey, Tohren C G; Paruchuri, Rajiv; Sabatini, David A; Chen, Lixia

    2007-08-01

    Beta-adrenergic blocking agents (beta blockers) are widely used pharmaceuticals which have been detected in the environment. Predicting the transport and ultimate fate of beta blockers in the environment requires understanding their adsorption to soils and sediments, something for which little information is currently available. The objective of this work was to examine the adsorption of three beta blockers, propranolol, metoprolol and nadolol, to a natural alluvial material, as well as to six minerals present as components of the alluvial material. Batch adsorption experiments indicate that, for most of the minerals studied, compound hydrophobicity is an important predictor of adsorption, with propranolol,the most hydrophobic compound studied, adsorbing to the greatest extent. Results further suggest that, for the minerals studied, electrostatic effects are not a good predictor of adsorption; adsorption extent was not well-predicted by either surface zeta potential or by the difference between experiment pH and point of zero charge, despite the cationic nature af the three beta blockers at experiment pH values. Experiments were conducted to examine the effect of an anionic surfactant, sodium dodecyl benzene sulfonate (SDBS), on adsorption. Results indicate that SDBS significantly increases the adsorption of propranolol to two different sorbents. This result is potentially important because surfactants such as SDBS are likely to be present in wastewater effluents with beta blockers and could influence their mobility in the environment.

  18. Polychelated cryogels: hemoglobin adsorption from human blood.

    PubMed

    Erol, Kadir

    2017-02-01

    The separation and purification methods are extremely important for the hemoglobin (Hb) which is a crucial biomolecule. The adsorption technique is popular among these methods and the cryogels have been used quite much due to their macropores and interconnected flow channels. In this study, the Hb adsorption onto the Cu(II) immobilized poly(2-hydroxyethyl methacrylate-glycidyl methacrylate), poly(HEMA-GMA)-Cu(II), cryogels was investigated under different conditions (pH, interaction time, initial Hb concentration, temperature and ionic strength) to optimize adsorption conditions. The swelling test, Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), surface area (BET), elemental and ICP-OES analysis were performed for the characterization of cryogels. Polyethyleneimine (PEI) molecule was used as a Cu(II)-chelating ligand. The Hb adsorption capacity of cryogels was determined as 193.8 mg Hb/g cryogel. The isolation of Hb from human blood was also studied under optimum adsorption conditions determined and the Hb (124.5 mg/g cryogel) was isolated. The adsorption model was investigated in the light of Langmuir and Freundlich adsorption isotherm models and it was determined to be more appropriate to the Langmuir adsorption isotherm model.

  19. 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...

  20. BSA adsorption on bimodal PEO brushes.

    PubMed

    Bosker, W T E; Iakovlev, P A; Norde, W; Cohen Stuart, M A

    2005-06-15

    BSA adsorption onto bimodal PEO brushes at a solid surface was measured using optical reflectometry. Bimodal brushes consist of long (N=770) and short (N=48) PEO chains and were prepared on PS surfaces, applying mixtures of PS(29)-PEO(48) and PS(37)-PEO(770) block copolymers and using the Langmuir-Blodgett technique. Pi-A isotherms of (mixtures of) the block copolymers were measured to establish the brush regime. The isotherms of PS(29)-PEO(48) show hysteresis between compression and expansion cycles, indicating aggregation of the PS(29)-PEO(48) upon compression. Mixtures of PS(29)-PEO(48) and PS(37)-PEO(770) demonstrate a similar hysteresis effect, which eventually vanishes when the ratio of PS(37)-PEO(770) to PS(29)-PEO(48) is increased. The adsorption of BSA was determined at brushes for which the grafting density of the long PEO chains was varied, while the total grafting density was kept constant. BSA adsorption onto monomodal PEO(48) and PEO(770) brushes was determined for comparison. The BSA adsorption behavior of the bimodal brushes is similar to the adsorption of BSA at PEO(770) monomodal brushes. The maximum of BSA adsorption at low grafting density of PEO(770) can be explained by ternary adsorption, implying an attraction between BSA and PEO. The contribution of primary adsorption to the total adsorbed amount is negligible.

  1. 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...

  2. Phosphoryl functionalized mesoporous silica for uranium adsorption

    NASA Astrophysics Data System (ADS)

    Xue, Guo; Yurun, Feng; Li, Ma; Dezhi, Gao; Jie, Jing; Jincheng, Yu; Haibin, Sun; Hongyu, Gong; Yujun, Zhang

    2017-04-01

    Phosphoryl functionalized mesoporous silica (TBP-SBA-15) was synthesized by modified mesoporous silica with γ-amino propyl triethoxy silane and tributyl phosphate. The obtained samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), small angle X-ray diffraction (SAXRD), thermo-gravimetric/differential thermalanalyzer (TG/DTA), N2 adsorption-desorption (BET) and Fourier transform infrared spectroscopy (FT-IR) techniques. Results showed that TBP-SBA-15 had large surface areas with ordered channel structure. Moreover, the effects of adsorption time, sorbent dose, solution pH, initial uranium concentration and temperature on the uranium adsorption behaviors were investigated. TBP-SBA-15 showed a high uranium adsorption capacity in a broad range of pH values. The U(VI) adsorption rate of TBP-SBA-15 was fast and nearly achieved completion in 10 min with the sorbent dose of 1 g/L. The U(VI) adsorption of TBP-SBA-15 followed the pseudo-second-order kinetic model and Freundlich isotherm model, indicating that the process was belonged to chemical adsorption. Furthermore, the thermodynamic parameters (ΔG0, ΔH0 and ΔS0) confirmed that the adsorption process was endothermic and spontaneous.

  3. 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.

  4. Factors affecting drug adsorption on beta zeolites.

    PubMed

    Pasti, Luisa; Sarti, Elena; Cavazzini, Alberto; Marchetti, Nicola; Dondi, Francesco; Martucci, Annalisa

    2013-05-01

    The adsorption behaviour of three commonly used drugs, namely ketoprofen, hydrochlorothiazide and atenolol, from diluted aqueous solutions on beta zeolites with different SiO2/Al2O3 ratio (i.e. 25, 38 and 360) was investigated by changing the ionic strength and the pH, before and after thermal treatment of the adsorbents. The selective adsorption of drugs was confirmed by thermogravimetry and X-ray diffraction. The adsorption capacity of beta zeolites was strongly dependent on both the solution pH and the alumina content of the adsorbent. Such a remarkable difference was interpreted as a function of the interactions between drug molecules and zeolite surface functional groups. Atenolol was readily adsorbed on the less hydrophobic zeolite, under pH conditions in which electrostatic interactions were predominant. On the other hand, ketoprofen adsorption was mainly driven by hydrophobic interactions. For undissociated molecules the adsorption capability increased with the increase of hydrophobicity.

  5. Adsorption and desorption of reversible supramolecular polymers

    NASA Astrophysics Data System (ADS)

    Zweistra, Henk J. A.; Besseling, N. A. M.

    2006-08-01

    We report numerical mean-field results on the quasichemical level of approximation that describe adsorption of reversible supramolecular polymers at a flat interface. Emphasis is laid on the regime of strong adsorption from a dilute solution. There are two differences with respect to macromolecular polymer adsorption: (i) adsorption sets in at relatively high monomer concentrations of the surrounding solution, and (ii) the surface is filled within a much narrower concentration range. Contrary to macromolecular polymers, supramolecular polymers can therefore be desorbed by dilution of the equilibrium solution by solvent within an experimentally accessible concentration window. Based on simple thermodynamic arguments, we provide a quantitative explanation why supramolecular polymers adsorb at relatively high concentrations. Moreover, we discuss the (by comparison) narrow concentration window wherein filling of the surface occurs. This is attributed to the cooperative nature of supramolecular polymer adsorption. The degree of cooperativity is quantified by means of the Hill parameter n .

  6. 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.

  7. 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

  8. 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

  9. Stoichiometric modelling of cell metabolism.

    PubMed

    Llaneras, Francisco; Picó, Jesús

    2008-01-01

    There are several methodologies based on representations of cell metabolism that share two characteristics: the use of a metabolic network and the assumption of pseudosteady state. These methodologies have different purposes, employ different mathematical tools and are based on different assumptions; however, they all exploit the properties of a similar mathematical description. In this article we use the term stoichiometric modelling to encompass all these methodologies and to describe them within a common framework. Although the information about reaction stoichiometry embedded in metabolic networks is highly important, the framework encompasses methodologies not limited to the use of stoichiometric information. To highlight this fact, the definition of the framework is approached from a constraint-based perspective. One of the reasons for the success of stoichiometric modelling is that it avoids the difficulties that arise in the development of kinetic models: a consequence of the lack of intracellular experimental measurements. Thus, it makes it possible to exploit the knowledge about the structure of cell metabolism, without considering the still not very well known intracellular kinetic processes. Stoichiometric models have been used to estimate the metabolic flux distribution under given circumstances in the cell at some given moment (metabolic flux analysis), to predict it on the basis of some optimality hypothesis (flux balance analysis), and as tools for the structural analysis of metabolism providing information about systemic characteristics of the cell under investigation (network-based pathway analysis).

  10. BTEX and MTBE adsorption onto raw and thermally modified diatomite.

    PubMed

    Aivalioti, Maria; Vamvasakis, Ioannis; Gidarakos, Evangelos

    2010-06-15

    The removal of BTEX (benzene, toluene, ethyl-benzene and xylenes) and MTBE (methyl tertiary butyl ether) from aqueous solution by raw (D(R)) and thermally modified diatomite at 550, 750 and 950 degrees C (D(550), D(750) and D(950) respectively) was studied. Physical characteristics of both raw and modified diatomite such as specific surface, pore volume distribution, porosity and pH(solution) were determined, indicating important structural changes in the modified diatomite, due to exposure to high temperatures. Both adsorption kinetic and isotherm experiments were carried out. The kinetics data proved a closer fit to the pseudo-second order model. Maximum values for the rate constant, k(2), were obtained for MTBE and benzene (48.9326 and 18.0996 g mg(-1)h(-1), respectively) in sample D(550). The isotherm data proved to fit the Freundlich model more closely, which produced values of the isotherm constant 1/n higher than one, indicating unfavorable adsorption. The highest adsorption capacity, calculated through the values of the isotherm constant k(F), was obtained for MTBE (48.42 mg kg(-1) (mg/L)(n)) in sample D(950).

  11. 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.

  12. 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.

  13. Paraquat adsorption onto clays and organoclays from aqueous solution.

    PubMed

    Seki, Y; Yurdakoç, K

    2005-07-01

    Clays were compared with organoclays for the sorption of paraquat from aqueous solution. Sepiolite (S), bentonite (B), and illite (I) were used as clay samples. Organoclays were prepared by the modification of the clays with nonyl- and dodecylammonium chlorides, denoted as NS, DS, NB, DB, NI, and DI, respectively. Specific surface area and pore size distribution of the samples were determined by N2 adsorption-desorption at 77 K using the BET method. X-ray powder diffraction analysis of the samples was used to determine the effects of modifying agents on the layer structure of the clays. In the adsorption experiments, C(m) values increased from 0.038 mmol/g for DS to 0.223 mmol/g for NI. Kd0.3 values ranged from 0.177 for DS to 0.843 for NI. The adsorption data indicated that illite and NI are the most effective adsorbents among these clays and organoclay samples, respectively.

  14. Exploring molecular sieve capabilities of activated carbon fibers to reduce the impact of NOM preloading on trichloroethylene adsorption.

    PubMed

    Karanfil, Tanju; Dastgheib, Seyed A; Mauldin, Dina

    2006-02-15

    Adsorption of trichloroethylene (TCE) by two activated carbon fibers (ACFs) and two granular activated carbons (GACs) preloaded with hydrophobic and transphilic fractions of natural organic matter (NOM) was examined. ACF10, the most microporous activated carbon used in this study, had over 90% of its pore volume in pores smaller than 10 A. It also had the highest volume in pores 5-8 A, which is the optimum pore size region for TCE adsorption, among the four activated carbons. Adsorption of NOM fractions by ACF10 was, in general, negligible. Therefore, ACF10, functioning as a molecular sieve during preloading, exhibited the least NOM uptake for each fraction, and subsequently the highest TCE adsorption. The other three sorbents had wider pore size distributions, including high volumes in pores larger than 10 A, where NOM molecules can adsorb. As a result, they showed a higher degree of uptake for all NOM fractions, and subsequently lower adsorption capacities for TCE, as compared to ACF10. The results obtained in this study showed that understanding the interplay between the optimum pore size region for the adsorption of target synthetic organic contaminant (SOC) and the pore size region for the adsorption of NOM molecules is important for controlling NOM-SOC competitions. Experiments with different NOM fractions indicated that the degree of NOM loading is important in terms of preloading effects; however the waythatthe carbon pores are filled and loaded by different NOM fractions can be different and may create an additional negative impact on TCE adsorption.

  15. 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...

  16. 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.

  17. 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.

  18. Adsorption behavior and mechanism of Cd(II) on loess soil from China.

    PubMed

    Wang, Yan; Tang, Xiaowu; Chen, Yunmin; Zhan, Liangtong; Li, Zhenze; Tang, Qiang

    2009-12-15

    Cadmium is a toxic heavy metal that has caused serious public health problems. It is necessary to find a cost effective method to deal with wastewater containing Cd(II). Loess soils in China have proven to be a potential adsorbent for Cd(II) removal from wastewater. The adsorption capacity of loess towards Cd(II) has been determined to be about 9.37 mg g(-1). Slurry concentration, initial solution pH, reaction time and temperature have also been found to significantly influence the efficiency of Cd(II) removal. The adsorption isotherms and kinetics of loess soil from China can be best-fit with the Langmuir model and pseudo-second order kinetics model, respectively. The thermodynamic analysis revealed that the adsorption process was spontaneous, endothermic and the system disorder increased with duration. The natural organic matter in loess soil is mainly responsible for Cd(II) removal at pH < 4.2, while clay minerals contribute to a further gradual adsorption process. Chemical precipitation dominates the adsorption stage at pH > 8.97. Further studies using X-ray diffraction, Fourier transform infrared spectra of Cd(II) laden loess soil and Cd(II) species distribution have confirmed the adsorption mechanism.

  19. Dibenzothiophene adsorption at boron doped carbon nanoribbons studied within density functional theory

    NASA Astrophysics Data System (ADS)

    López-Albarrán, P.; Navarro-Santos, P.; Garcia-Ramirez, M. A.; Ricardo-Chávez, J. L.

    2015-06-01

    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 BC3 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.

  20. 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.

  1. A quantitative speciation model for the adsorption of organic pollutants on activated carbon.

    PubMed

    Grivé, M; García, D; Domènech, C; Richard, L; Rojo, I; Martínez, X; Rovira, M

    2013-01-01

    Granular activated carbon (GAC) is commonly used as adsorbent in water treatment plants given its high capacity for retaining organic pollutants in aqueous phase. The current knowledge on GAC behaviour is essentially empirical, and no quantitative description of the chemical relationships between GAC surface groups and pollutants has been proposed. In this paper, we describe a quantitative model for the adsorption of atrazine onto GAC surface. The model is based on results of potentiometric titrations and three types of adsorption experiments which have been carried out in order to determine the nature and distribution of the functional groups on the GAC surface, and evaluate the adsorption characteristics of GAC towards atrazine. Potentiometric titrations have indicated the existence of at least two different families of chemical groups on the GAC surface, including phenolic- and benzoic-type surface groups. Adsorption experiments with atrazine have been satisfactorily modelled with the geochemical code PhreeqC, assuming that atrazine is sorbed onto the GAC surface in equilibrium (log Ks = 5.1 ± 0.5). Independent thermodynamic calculations suggest a possible adsorption of atrazine on a benzoic derivative. The present work opens a new approach for improving the adsorption capabilities of GAC towards organic pollutants by modifying its chemical properties.

  2. 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

    2014-05-07

    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.

  3. 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.

  4. 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.

  5. Temperature Swing Adsorption Compressor Development

    NASA Technical Reports Server (NTRS)

    Finn, John E.; Mulloth, Lila M.; Affleck, Dave L.

    2001-01-01

    Closing the oxygen loop in an air revitalization system based on four-bed molecular sieve and Sabatier reactor technology requires a vacuum pump-compressor that can take the low-pressure CO, from the 4BMS and compress and store for use by a Sabatier reactor. NASA Ames Research Center proposed a solid-state temperature-swing adsorption (TSA) compressor that appears to meet performance requirements, be quiet and reliable, and consume less power than a comparable mechanical compressor/accumulator combination. Under this task, TSA compressor technology is being advanced through development of a complete prototype system. A liquid-cooled TSA compressor has been partially tested, and the rest of the system is being fabricated. An air-cooled TSA compressor is also being designed.

  6. [Metabolic syndrome].

    PubMed

    Takata, Hiroshi; Fujimoto, Shimpei

    2013-02-01

    Metabolic syndrome (Mets) is a combination of disorders including abdominal obesity, impaired glucose tolerance, dyslipidemia and hypertension, which increases risk for cardiovascular disease (CVD) and type 2 diabetes when occurring together. In Japan, diagnosis criteria of Mets consists of an increased waist circumference and 2 or more of CVD risk factors. Annual health checkups and health guidance using Mets criteria were established in 2008 for the prevention of life-style related diseases in Japan. In this issue, history and diagnostic criteria of Mets and concerns for Mets concept were described.

  7. Theoretical study of adsorption of tabun on calcium oxide clusters

    NASA Astrophysics Data System (ADS)

    Michalkova, A.; Paukku, Y.; Majumdar, D.; Leszczynski, J.

    2007-04-01

    Interactions of tabun (GA) with non-hydroxylated and hydroxylated CaO clusters have been studied using density functional (DFT) and Møller-Plesset second order perturbation (MP2) levels of theory. The nature of interactions has been further investigated from the topology of charge distribution (using Atoms in Molecules formalism) and molecular electrostatic potential (MEP) surfaces. These adsorption studies indicate that GA adsorbs strongly on the non-hydroxylated CaO cluster through its P dbnd O bond, while interactions of GA on the hydroxylated cluster are weak. These model studies could thus be useful to characterize inorganic oxides for efficient detection and disposal of GA.

  8. 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.

  9. 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.

  10. 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...

  11. Adsorption of water vapor by poly(styrenesulfonic acid), sodium salt: isothermal and isobaric adsorption equilibria.

    PubMed

    Toribio, F; Bellat, J P; Nguyen, P H; Dupont, M

    2004-12-15

    Air conditioning and dehumidifying systems based on sorption on solids are of great interest, especially in humid climates, because they allow reduction of thermal loads and use of chlorofluorocarbons. Previous studies have shown that hydrophilic polymers such as sulfonic polymers can have very high performance in water adsorption from air. The aim of this study was to characterize the water vapor adsorption properties of fully sulfonated and monosulfonated poly(styrenesulfonic acid), sodium salt, and to elucidate the mechanism of adsorption on these materials. Adsorption isotherms have been determined by TGA between 298 and 317 K for pressures ranging from 0.1 to 45 hPa. They have type II of the IUPAC classification and a small hysteresis loop between adsorption and desorption processes was observed only for the monosulfonated sample. Water content is up to 80% weight at 80% relative humidity. Adsorption isotherms have been well fitted with the FHH model. Adsorption-desorption isobars have been determined by TGA under 37 hPa in the temperature range 298-373 K. They show that these polymers can be completely regenerated by heating at 313 K under humidified air. No degradation of the adsorption properties has been observed after several regenerations. Adsorption enthalpies and entropies have been deduced from the Clapeyron equation and from DSC measurements. A good agreement was found. A mechanism of adsorption is proposed considering two kinds of adsorbate: bounded water in electrostatic interaction with functional groups and free water resulting from condensation.

  12. Modeling the adsorption of mixed gases based on pure gas adsorption properties

    NASA Astrophysics Data System (ADS)

    Tzabar, N.; Holland, H. J.; Vermeer, C. H.; ter Brake, H. J. M.

    2015-12-01

    Sorption-based Joule-Thomson (JT) cryocoolers usually operate with pure gases. A sorption-based compressor has many benefits; however, it is limited by the pressure ratios it can provide. Using a mixed-refrigerant (MR) instead of a pure refrigerant in JT cryocoolers allows working at much lower pressure ratios. Therefore, it is attractive using MRs in sorption- based cryocoolers in order to reduce one of its main limitations. The adsorption of mixed gases is usually investigated under steady-state conditions, mainly for storage and separation processes. However, the process in a sorption compressor goes through various temperatures, pressures and adsorption concentrations; therefore, it differs from the common mixed gases adsorption applications. In order to simulate the sorption process in a compressor a numerical analysis for mixed gases is developed, based on pure gas adsorption characteristics. The pure gas adsorption properties have been measured for four gases (nitrogen, methane, ethane, and propane) with Norit-RB2 activated carbon. A single adsorption model is desired to describe the adsorption of all four gases. This model is further developed to a mixed-gas adsorption model. In future work more adsorbents will be tested using these four gases and the adsorption model will be verified against experimental results of mixed-gas adsorption measurements.

  13. Metabolic Networks

    NASA Astrophysics Data System (ADS)

    Palumbo, Maria Concetta; Farina, Lorenzo; Colosimo, Alfredo; Giuliani, Alessandro

    The use of the term `network' is more and more widespread in all fields of biology. It evokes a systemic approach to biological problems able to overcome the evident limitations of the strict reductionism of the past twenty years. The expectations produced by taking into considerations not only the single elements but even the intermingled `web' of links connecting different parts of biological entities, are huge. Nevertheless, we believe that the lack of consciousness that networks, beside their biological `likelihood', are modeling tools and not real entities, could be detrimental to the exploitation of the full potential of this paradigm. Like any modeling tool the network paradigm has a range of application going from situations in which it is particularly fit to situations in which its application can be largely misleading. In this chapter we deal with an aspect of biological entities that is particularly fit for the network approach: the intermediate metabolism. This fit derives both from the existence of a privileged formalization in which the relative role of nodes (metabolites) and arches (enzymes) is immediately suggested by the system architecture. Here we will discuss some applications of both graph theory based analysis and multidimensional statistics method to metabolic network studies with the emphasis on the derivation of biologically meaningful information.

  14. Monte Carlo simulations of Protein Adsorption

    NASA Astrophysics Data System (ADS)

    Sharma, Sumit; Kumar, Sanat K.; Belfort, Georges

    2008-03-01

    Amyloidogenic diseases, such as, Alzheimer's are caused by adsorption and aggregation of partially unfolded proteins. Adsorption of proteins is a concern in design of biomedical devices, such as dialysis membranes. Protein adsorption is often accompanied by conformational rearrangements in protein molecules. Such conformational rearrangements are thought to affect many properties of adsorbed protein molecules such as their adhesion strength to the surface, biological activity, and aggregation tendency. It has been experimentally shown that many naturally occurring proteins, upon adsorption to hydrophobic surfaces, undergo a helix to sheet or random coil secondary structural rearrangement. However, to better understand the equilibrium structural complexities of this phenomenon, we have performed Monte Carlo (MC) simulations of adsorption of a four helix bundle, modeled as a lattice protein, and studied the adsorption behavior and equilibrium protein conformations at different temperatures and degrees of surface hydrophobicity. To study the free energy and entropic effects on adsorption, Canonical ensemble MC simulations have been combined with Weighted Histogram Analysis Method(WHAM). Conformational transitions of proteins on surfaces will be discussed as a function of surface hydrophobicity and compared to analogous bulk transitions.

  15. Functionalized SBA-15 materials for bilirubin adsorption

    NASA Astrophysics Data System (ADS)

    Tang, Tao; Zhao, Yanling; Xu, Yao; Wu, Dong; Xu, Jun; Deng, Feng

    2011-05-01

    To investigate the driving force for bilirubin adsorption on mesoporous materials, a comparative study was carried out between pure siliceous SBA-15 and three functionalized SBA-15 mesoporous materials: CH 3-SBA-15 (MS), NH 2-SBA-15 (AS), and CH 3/NH 2-SBA-15 (AMS) that were synthesized by one-pot method. The obtained materials exhibited large surface areas (553-810 m 2/g) and pore size (6.6-7.1 nm) demonstrated by XRD and N 2-ad/desorption analysis. The SEM images showed that the materials had similar fiberlike morphology. The functionalization extent was calculated according to 29Si MAS NMR spectra and it was close to the designed value (10%). The synthesized mesoporous materials were used as bilirubin adsorbents and showed higher bilirubin adsorption capacities than the commercial active carbon. The adsorption capacities of amine functionalized samples AMS and AS were larger than those of pure siliceous SBA-15 and MS, indicating that electrostatic interaction was the dominant driving force for bilirubin adsorption on mesoporous materials. Increasing the ionic strength of bilirubin solution by adding NaCl would decrease the bilirubin adsorption capacity of mesoporous material, which further demonstrated that the electrostatic interaction was the dominant driving force for bilirubin adsorption. In addition, the hydrophobic interaction provided by methyl groups could promote the bilirubin adsorption.

  16. 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.

  17. Effects of topology on the adsorption of singly tethered ring polymers to attractive surfaces.

    PubMed

    Li, Bing; Sun, Zhao-Yan; An, Li-Jia

    2015-07-14

    We investigate the effect of topology on the equilibrium behavior of singly tethered ring polymers adsorbed on an attractive surface. We focus on the change of square radius of gyration Rg(2), the perpendicular component Rg⊥(2) and the parallel component Rg‖(2) to the adsorbing surface, the mean contacting number of monomers with the surface , and the monomer distribution along z-direction during transition from desorption to adsorption. We find that both of the critical point of adsorption εc and the crossover exponent ϕ depend on the knot type when the chain length of ring ranges from 48 to 400. The behaviors of Rg(2), Rg⊥(2), and Rg‖(2) are found to be dependent on the topology and the monomer-surface attractive strength. At weak adsorption, the polymer chains with more complex topology are more adsorbable than those with simple topology. However, at strong adsorption, the polymer chains with complex topology are less adsorbable. By analyzing the distribution of monomer along z-direction, we give a possible mechanism for the effect of topology on the adsorption behavior.

  18. 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.

  19. Monte Carlo simulations of adsorption on heterogeneous surfaces with a random topography of surfaces sites

    NASA Astrophysics Data System (ADS)

    Cortes, Joaquin; Araya, Paulo

    1991-11-01

    Making use of Monte Carlo experiments, a simulation has been carried out of the adsorption of a gas on heterogeneous solids characterized by energy distribution and a random topography of the superficial sites. A good interpretation of the results is achieved by means of the theoretical models introduced by Hill, and later by Rudzinsky, for these types of systems.

  20. Adsorption of amylase enzyme on ultrafiltration membranes.

    PubMed

    Beier, Søren Prip; Enevoldsen, Ann Dorrit; Kontogeorgis, Georgios M; Hansen, Ernst B; Jonsson, Gunnar

    2007-08-28

    A method to measure the static adsorption on membrane surfaces has been developed and described. The static adsorption of amylase-F has been measured on two different ultrafiltration membranes, both with a cutoff value of 10 kDa (a PES membrane and the ETNA10PP membrane, which is a surface-modified PVDF membrane). The adsorption follows the Langmuir adsorption theory. Thus, the static adsorption consists of monolayer coverage and is expressed both as a permeability drop and an adsorption resistance. From the adsorption isotherms, the maximum static permeability drops and the maximum static adsorption resistances are determined. The maximum static permeability drop for the hydrophobic PES membrane is 75%, and the maximum static adsorption resistance is 0.014 m2.h.bar/L. The maximum static permeability drop for the hydrophilic surface-modified PVDF membrane (ETNA10PP) is 23%, and the maximum static adsorption resistance is 0.0046 m2.h.bar/L. The difference in maximum static adsorption, by a factor of around 3, affects the performance during the filtration of a 5 g/L amylase-F solution at 2 bar. The two membranes behave very similarly during filtration with almost equal fluxes and retentions even though the initial water permeability of the PES membrane is around 3 times larger than the initial water permeability of the ETNA10PP membrane. This is mainly attributed to the larger maximum static adsorption of the PES membrane. The permeability drop during filtration exceeds the maximum static permeability drop, indicating that the buildup layer on the membranes during filtration exceeds monolayer coverage, which is also seen by the increase in fouling resistance during filtration. The accumulated layer on the membrane surface can be described as a continually increasing cake-layer thickness, which is independent of the membrane type. At higher concentrations of enzyme, concentration polarization effects cannot be neglected. Therefore, stagnant film theory and the osmotic

  1. Apparatus for the study of macromolecular adsorption

    NASA Astrophysics Data System (ADS)

    Mayo, C. S.; Hallock, R. B.

    1989-04-01

    A surface plasmon adsorbate monitor (SPAM) is described which allows the adsorption of macromolecules or other adsorbates to a metal surface to be monitored. Surface plasmons are employed and the apparatus has no moving parts. The kinetics of adsorption may be studied on a time scale of seconds rather than the more common time scale of minutes; a simple improvement in computer memory access should allow temporal studies in the millisecond range. As an illustration, the adsorption of carboxyl-terminated polystyrene from a solution with acetone onto a silver surface is measured.

  2. Adsorption of lead over graphite oxide.

    PubMed

    Olanipekun, Opeyemi; Oyefusi, Adebola; Neelgund, Gururaj M; Oki, Aderemi

    2014-01-24

    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 Pb(2+) 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.

  3. 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.

  4. 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).

  5. 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.

  6. 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)

  7. Capillary condensation and adsorption of binary mixtures.

    PubMed

    Weinberger, B; Darkrim-Lamari, F; Levesque, D

    2006-06-21

    The adsorption of equimolar binary mixtures of hydrogen-carbon dioxide, hydrogen-methane, and methane-carbon dioxide in porous material models is determined by grand canonical Monte Carlo simulations. The material models have an adsorbent surface similar to that of nanofibers with a herringbone structure. Our main result, which is relevant for hydrogen purification and carbon dioxide capture, is that the adsorption selectivities calculated for the mixtures can differ significantly from those deduced from simulations of the adsorption of pure gases, in particular, when one of the adsorbed gases presents a capillary condensation induced by confinement within the pore network. A comparison of our data is also made with theoretical models used in the literature for predicting the properties of the mixture adsorption.

  8. 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.

  9. 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.

  10. H2O Adsorption Kinetics on Smectites

    NASA Technical Reports Server (NTRS)

    Zent, Aaron P.; Howard, J.; Quinn, R. C.

    2000-01-01

    The adsorptive equilibration of H2O with montomorillonite has been measured. At low temperatures and pressures equilibration can require many hours, effectively preventing smectites at the martian surface from responding to diurnal pressure and temperature variations.

  11. 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.

  12. 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.

  13. 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

  14. Methane adsorption on aggregates of fullerenes: site-selective storage capacities and adsorption energies.

    PubMed

    Kaiser, Alexander; Zöttl, Samuel; Bartl, Peter; Leidlmair, Christian; Mauracher, Andreas; Probst, Michael; Denifl, Stephan; Echt, Olof; Scheier, Paul

    2013-07-01

    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.

  15. 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.

  16. Adsorption of argon on sintered tin dioxide analyzed by several methods

    NASA Technical Reports Server (NTRS)

    Hinman, D. C.; Halsey, G. D.

    1977-01-01

    Argon adsorption measurements are presented over a wide range of temperature and coverage on a series of three progressively sintered SnO2 surfaces. These data are analyzed by mercury porosimetry, the BET method, the CAEDMON distribution analysis, and the Singleton-Halsey equation. Isosteric heats are computed, and the high-temperature virial expansion of the data presented. The advantages and disadvantages of each method are discussed with particular attention to the ability of physical adsorption to discriminate among surfaces beyond the measurement of surface area.

  17. Xenon adsorption in NaA zeolite cavities

    NASA Astrophysics Data System (ADS)

    McCormick, A. V.; Chmelka, B. F.

    Adsorption of xenon atoms in the α-cages of NaA zeolite has been studied using 129Xe NMR spectroscopy to probe directly the distribution and configuration of molecules in confined, microporous environments. The 129Xe NMR spectrum is sensitive to subtle changes in xenon environment, so relative populations of α-cages containing different numbers of xenon guests can be determined and the effects of other co-adsorbed species monitored. On the basis of 129Xe NMR spectra, the distribution of xenon atoms among NaA α-cages is shown to exhibit a marked dependence on the pressure at which the xenon guests are introduced. 129Xe NMR spectra recorded at 200 K reveal that xenon atoms in the NaA α-cages experience diminished mobility (resembling condensation phenomena) at higher temperatures than in the bulk gas of equivalent density. Thus, the chemical potential of adsorbed xenon can be investigated experimentally as a function of both temperature and guest density. The density dependence of the 129Xe chemical shift in Xe/NaA and in bulk xenon gas shows that Xe-Xe interactions in the proximity of the NaA cage wall are important in α-cages containing more than five xenon guests. This trend is linked to entropic effects which may enhance xenon adsorption in the confined environment of the NaA α-cages.

  18. Defluoridation of drinking water using adsorption processes.

    PubMed

    Loganathan, Paripurnanda; Vigneswaran, Saravanamuthu; Kandasamy, Jaya; Naidu, Ravi

    2013-03-15

    Excessive intake of fluoride (F), mainly through drinking water, is a serious health hazard affecting humans worldwide. There are several methods used for the defluoridation of drinking water, of which adsorption processes are generally considered attractive because of their effectiveness, convenience, ease of operation, simplicity of design, and for economic and environmental reasons. In this paper, we present a comprehensive and a critical literature review on various adsorbents used for defluoridation, their relative effectiveness, mechanisms and thermodynamics of adsorption, and suggestions are made on choice of adsorbents for various circumstances. Effects of pH, temperature, kinetics and co-existing anions on F adsorption are also reviewed. Because the adsorption is very weak in extremely low or high pHs, depending on the adsorbent, acids or alkalis are used to desorb F and regenerate the adsorbents. However, adsorption capacity generally decreases with repeated use of the regenerated adsorbent. Future research needs to explore highly efficient, low cost adsorbents that can be easily regenerated for reuse over several cycles of operations without significant loss of adsorptive capacity and which have good hydraulic conductivity to prevent filter clogging during the fixed-bed treatment process.

  19. Gibbs adsorption and the compressibility equation

    SciTech Connect

    Aranovich, G.L.; Donohue, M.D.

    1995-08-08

    A new approach for deriving the equation of state is developed. It is shown that the integral in the compressibility equation is identical to the isotherm for Gibbs adsorption in radial coordinates. The Henry, Langmuir, and Frumkin adsorption isotherms are converted into equations of state. It is shown that using Henry`s law gives an expression for the second virial coefficient that is identical to the result from statistical mechanics. Using the Langmuir isotherm leads to a new analytic expression for the hard-sphere equation of state which can be explicit in either pressure or density. The Frumkin isotherm results in a new equation of state for the square-well potential fluid. Conversely, new adsorption isotherms can be derived from equations of state using the compressibility equation. It is shown that the van der Waals equation gives an adsorption isotherm equation that describes both polymolecular adsorption and the unusual adsorption behavior observed for supercritical fluids. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  20. Differential Heat of Adsorption and Isosteres.

    PubMed

    Tian, Yun; Wu, Jianzhong

    2017-01-31

    Heat of adsorption is a basic thermodynamic property extensively used not only for understanding thermal effects and heat management in industrial gas storage and separation processes but also for development and validation of adsorption models and materials force fields. Despite a long history of theoretical studies and a vast experimental literature, controversies often arise in the thermodynamic analysis of heat effects due to various assumptions used to describe gas adsorption and inconsistencies between direct calorimetric measurements and isosteric heat obtained from various adsorption isotherms. Here we present a rigorous theoretical procedure for predicting isosteric heat without any assumption about the geometry of porous adsorbents or operating conditions. Quantitative relations between the differential heat and various isosteres have been established with the grand-canonical Monte Carlo simulation for gas adsorption in amorphous as well as crystalline porous materials. The inconsistencies and practical issues with conventional methods for the analysis of the heat effect have been clarified in the context of the exact results for model systems. Via the resolution of a number of controversies about heat analysis, we hope that the new theoretical procedure will be adopted for both fundamental research and industrial applications of gas adsorption processes.

  1. Gas adsorption capacity of wood pellets

    DOE PAGES

    Yazdanpanah, F.; Sokhansanj, Shahabaddine; Lim, C. Jim; ...

    2016-02-03

    In this paper, temperature-programmed desorption (TPD) analysis was used to measure and analyze the adsorption of off-gases and oxygen by wood pellets during storage. Such information on how these gases interact with the material helps in the understanding of the purging/stripping behavior of off-gases to develop effective ventilation strategies for wood pellets. Steam-exploded pellets showed the lowest carbon dioxide (CO2) uptake compared to the regular and torrefied pellets. The high CO2 adsorption capacity of the torrefied pellets could be attributed to their porous structure and therefore greater available surface area. Quantifying the uptake of carbon monoxide by pellets was challengingmore » due to chemical adsorption, which formed a strong bond between the material and carbon monoxide. The estimated energy of desorption for CO (97.8 kJ/mol) was very high relative to that for CO2 (7.24 kJ/mol), demonstrating the mechanism of chemical adsorption and physical adsorption for CO and CO2, respectively. As for oxygen, the strong bonds that formed between the material and oxygen verified the existence of chemical adsorption and formation of an intermediate material.« less

  2. Gas adsorption capacity of wood pellets

    SciTech Connect

    Yazdanpanah, F.; Sokhansanj, Shahabaddine; Lim, C. Jim; Lau, A.; Bi, X. T.

    2016-02-03

    In this paper, temperature-programmed desorption (TPD) analysis was used to measure and analyze the adsorption of off-gases and oxygen by wood pellets during storage. Such information on how these gases interact with the material helps in the understanding of the purging/stripping behavior of off-gases to develop effective ventilation strategies for wood pellets. Steam-exploded pellets showed the lowest carbon dioxide (CO2) uptake compared to the regular and torrefied pellets. The high CO2 adsorption capacity of the torrefied pellets could be attributed to their porous structure and therefore greater available surface area. Quantifying the uptake of carbon monoxide by pellets was challenging due to chemical adsorption, which formed a strong bond between the material and carbon monoxide. The estimated energy of desorption for CO (97.8 kJ/mol) was very high relative to that for CO2 (7.24 kJ/mol), demonstrating the mechanism of chemical adsorption and physical adsorption for CO and CO2, respectively. As for oxygen, the strong bonds that formed between the material and oxygen verified the existence of chemical adsorption and formation of an intermediate material.

  3. Carbon dioxide adsorption in graphene sheets

    NASA Astrophysics Data System (ADS)

    Mishra, Ashish Kumar; Ramaprabhu, Sundara

    2011-09-01

    Control over the CO2 emission via automobiles and industrial exhaust in atmosphere, is one of the major concerns to render environmental friendly milieu. Adsorption can be considered to be one of the more promising methods, offering potential energy savings compared to absorbent systems. Different carbon nanostructures (activated carbon and carbon nanotubes) have attracted attention as CO2 adsorbents due to their unique surface morphology. In the present work, we have demonstrated the CO2 adsorption capacity of graphene, prepared via hydrogen induced exfoliation of graphitic oxide at moderate temperatures. The CO2 adsorption study was performed using high pressure Sieverts apparatus and capacity was calculated by gas equation using van der Waals corrections. Physical adsorption of CO2 molecules in graphene was confirmed by FTIR study. Synthesis of graphene sheets via hydrogen exfoliation is possible at large scale and lower cost and higher adsorption capacity of as prepared graphene compared to other carbon nanostructures suggests its possible use as CO2 adsorbent for industrial application. Maximum adsorption capacity of 21.6 mmole/g was observed at 11 bar pressure and room temperature (25 °C).

  4. 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 ...

  5. 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...

  6. Scattering, Adsorption, and Langmuir-Hinshelwood Desorption Models for Physisorptive and Chemisorptive Gas-Surface Systems

    NASA Astrophysics Data System (ADS)

    Bentley, Brook I.

    Surface effects limit the performance of hypersonic vehicles, micro-electro-mechanical devices, and directed energy systems. This research develops methods to predict adsorption, scattering, and thermal desorption of molecules on a surface. These methods apply to physisorptive (adsorption and scattering) and chemisorptive (thermal desorption) gas-surface systems. Engineering and design applications will benefit from these methods, hence they are developed under the Direct Simulation Monte Carlo construct. The novel adsorption and scattering contribution, the Modified Kisliuk with Scattering method, predicts angular and energy distributions, and adsorption probabilities. These results agree more closely with experiment than the state-of-the-art Cercignani-Lampis-Lord scattering kernel. Super-elastic scattering is predicted. Gas-adlayer interactions are included for the first time. Accommodation coefficents can be determined by fitting simulations to experimental data. The new thermal desorption model accurately calculates angular, translational, rotational, and vibrational distributions, and the rotational alignment parameter. The model is validated by comparing with experiments. Multiple transition states are considered in a set of non-dimensionalized equations of motion, linked with temporally-accurate event timing. Initial conditions are chosen from a new truncated Maxwell-Boltzmann distribution. Run times are improved by eliminating the Gaussian Weighting of desorbing products. The absorption energy barrier is shown to significantly contribute only to the translational energy of desorbing molecules by contributing energy to each adatom in a similar manner.

  7. 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

    2016-06-05

    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.

  8. Adsorption equilibrium and kinetics of CO2, CH4, N2O, and NH3 on ordered mesoporous carbon.

    PubMed

    Saha, Dipendu; Deng, Shuguang

    2010-05-15

    Ordered mesoporous carbon was synthesized by a self-assembly technique and characterized with TEM, Raman spectroscopy, and nitrogen adsorption/desorption for its physical and pore textural properties. The high BET specific surface area (798 m(2)/g), uniform mesopore-size distribution with a median pore size of 62.6 Å, and large pore volume (0.87 cm(3)/g) make the ordered mesoporous carbon an ideal adsorbent for gas separation and purification applications. Adsorption equilibrium and kinetics of carbon dioxide, methane, nitrous oxide, and ammonia on the ordered mesoporous carbon were measured at 298 K and gas pressures up to 800 Torr. The adsorption equilibrium capacities on the ordered mesoporous carbon at 298 K and 800 Torr for ammonia, carbon dioxide, nitrous oxide, and methane were found to be 6.39, 2.39, 1.5, and 0.53 mmol/g, respectively. Higher adsorption uptakes of methane (3.26 mmol/g at 100 bar) and carbon dioxide (2.21 mmol/g at 13 bar) were also observed at 298 K and elevated pressures. Langmuir, Freundlich, and Toth adsorption equilibrium models were used to correlate all the adsorption isotherms, and a simplified gas diffusion model was applied to analyze the adsorption kinetics data collected at 298 K and four different gas pressures up to 800 Torr.

  9. Adsorption of aromatic compounds by carbonaceous adsorbents: a comparative study on granular activated carbon, activated carbon fiber, and carbon nanotubes.

    PubMed

    Zhang, Shujuan; Shao, Ting; Kose, H Selcen; Karanfil, Tanju

    2010-08-15

    Adsorption of three aromatic organic compounds (AOCs) by four types of carbonaceous adsorbents [a granular activated carbon (HD4000), an activated carbon fiber (ACF10), two single-walled carbon nanotubes (SWNT, SWNT-HT), and a multiwalled carbon nanotube (MWNT)] with different structural characteristics but similar surface polarities was examined in aqueous solutions. Isotherm results demonstrated the importance of molecular sieving and micropore effects in the adsorption of AOCs by carbonaceous porous adsorbents. In the absence of the molecular sieving effect, a linear relationship was found between the adsorption capacities of AOCs and the surface areas of adsorbents, independent of the type of adsorbent. On the other hand, the pore volume occupancies of the adsorbents followed the order of ACF10 > HD4000 > SWNT > MWNT, indicating that the availability of adsorption site was related to the pore size distributions of the adsorbents. ACF10 and HD4000 with higher microporous volumes exhibited higher adsorption affinities to low molecular weight AOCs than SWNT and MWNT with higher mesopore and macropore volumes. Due to their larger pore sizes, SWNTs and MWNTs are expected to be more efficient in adsorption of large size molecules. Removal of surface oxygen-containing functional groups from the SWNT enhanced adsorption of AOCs.

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. Highly enhanced adsorption for decontamination of lead ions from battery wastewaters using chitosan functionalized with xanthate.

    PubMed

    Chauhan, Divya; Sankararamakrishnan, Nalini

    2008-12-01

    Decontamination of lead ions from aqueous media has been investigated using cross linked xanthated chitosan (CMC) as an adsorbent. Various physico-chemical parameters such as contact time, amount of adsorbent, concentration of adsorbate were optimized to simulate the best conditions which can be used to decontaminate lead from aqueous media using CMC as an adsorbent. The atomic absorption spectrometric technique was used to determine the distribution of lead. Maximum adsorption was observed at both pH 4 and 5. The adsorption data followed both Freundlich and Langmuir isotherms. Langmuir isotherm gave a saturated capacity of 322.6+/-1.2mg/g at pH 4. From the FTIR spectra analysis, it was concluded that xanthate and amino group participate in the adsorption process. The developed procedure was successfully applied for the removal of lead ions from real battery wastewater samples.

  15. Adsorption behavior of ternary mixtures of noble gases inside single-walled carbon nanotube bundles

    NASA Astrophysics Data System (ADS)

    Foroutan, Masumeh; Nasrabadi, Amir Taghavi

    2010-09-01

    In order to study the gas-storage and gas-filtering capability of carbon nanotube (CNT) bundles simultaneously, we considered the adsorption behavior of a ternary mixture of noble gases, including Argon (Ar), Krypton (Kr), and Xenon (Xe), i.e., Ar-Kr-Xe mixture, on (10, 10) single-walled carbon nanotube (SWCNT) bundles. Molecular dynamics (MD) simulations at different temperatures of (75, 100, 150, 200, 250, and 300) K were performed, and adsorption energies, self-diffusion coefficients, activation energies, and radial distribution functions (RDFs) were computed to analyze the thermodynamics, transport and structural properties of the adsorption systems. It is observed that the SWCNT bundles have larger contents of heavier noble gases compared to the lighter ones. This interesting behavior of SWCNT bundles makes them proper candidates for gas-storage and gas molecular-sieving processes.

  16. 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

  17. Energy metabolism during human pregnancy.

    PubMed

    Forsum, Elisabet; Löf, Marie

    2007-01-01

    This review summarizes information regarding how human energy metabolism is affected by pregnancy, and current estimates of energy requirements during pregnancy are presented. Such estimates can be calculated using either increases in basal metabolic rate (BMR) or increases in total energy expenditure (TEE). The two modes of calculation give similar results for a complete pregnancy but different distributions of energy requirements in the three trimesters. Recent information is presented regarding the effect of pregnancy on BMR, TEE, diet-induced thermogenesis, and physical activity. The validity of energy intake (EI) data recently assessed in well-nourished pregnant women was evaluated using information regarding energy metabolism during pregnancy. The results show that underreporting of EI is common during pregnancy and indicate that additional longitudinal studies, taking the total energy budget during pregnancy into account, are needed to satisfactorily define energy requirements during the three trimesters of gestation.

  18. 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.

  19. Heavy metal adsorption changes of EAF steel slag after phosphorus adsorption.

    PubMed

    Song, Guanling; Cao, Lijing; Chen, Xiao; Hou, Wenhua; Wang, Qunhui

    2012-01-01

    A kind of electric arc furnace (EAF) steel slag was phosphated, and its isothermal and dynamic adsorptions of copper, cadmium, and lead ions were measured to determine if heavy metal adsorption changes after phosphorus adsorption. The surface area increased greatly after the slag was phosphated. Isothermal adsorption experiments showed that the theoretical Q(max) of the EAF steel slag on Cu(2+), Cd(2+), and Pb(2+) improved 59, 50, and 89% respectively after it was phosphated. Dynamic adsorption results showed that the greatest adsorption capacities of unit volume of Cu(2+), Cd(2+), and Pb(2+) were 2.2, 1.8, and 1.8 times that of the column packed with original EAF steel slag when the column was packed with phosphate EAF steel slag at the same heavy metal ion concentration. The breakthrough time, the exhaustion time and elution efficiency of the column also increased when the column was packed with phosphated EAF steel slag compared with that packed with original EAF steel slag. Phosphorus adsorption could further improve the heavy metal ion adsorption of the EAF steel slag.

  20. Analysis of metabolic flux using dynamic labelling and metabolic modelling.

    PubMed

    Fernie, A R; Morgan, J A

    2013-09-01

    Metabolic fluxes and the capacity to modulate them are a crucial component of the ability of the plant cell to react to environmental perturbations. Our ability to quantify them and to attain information concerning the regulatory mechanisms that control them is therefore essential to understand and influence metabolic networks. For all but the simplest of flux measurements labelling methods have proven to be the most informative. Both steady-state and dynamic labelling approaches have been adopted in the study of plant metabolism. Here the conceptual basis of these complementary approaches, as well as their historical application in microbial, mammalian and plant sciences, is reviewed, and an update on technical developments in label distribution analyses is provided. This is supported by illustrative cases studies involving the kinetic modelling of secondary metabolism. One issue that is particularly complex in the analysis of plant fluxes is the extensive compartmentation of the plant cell. This problem is discussed from both theoretical and experimental perspectives, and the current approaches used to address it are assessed. Finally, current limitations and future perspectives of kinetic modelling of plant metabolism are discussed.

  1. The Metabolic Cost of Sound Production in Odontocete Cetaceans

    DTIC Science & Technology

    2011-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. The Metabolic Cost of Sound Production in Odontocete...strategy to help reduce the probability of masking from environmental sounds (NRC 2003). Although accumulating evidence from recent research...data on the metabolic cost of sound production for any marine mammal species. Given that changes in vocal behavior in response to masking noise

  2. Modeling adsorption: Investigating adsorbate and adsorbent properties

    NASA Astrophysics Data System (ADS)

    Webster, Charles Edwin

    1999-12-01

    Surface catalyzed reactions play a major role in current chemical production technology. Currently, 90% of all chemicals are produced by heterogeneously catalyzed reactions. Most of these catalyzed reactions involve adsorption, concentrating the substrate(s) (the adsorbate) on the surface of the solid (the adsorbent). Pore volumes, accessible surface areas, and the thermodynamics of adsorption are essential in the understanding of solid surface characteristics fundamental to catalyst and adsorbent screening and selection. Molecular properties such as molecular volumes and projected molecular areas are needed in order to convert moles adsorbed to surface volumes and areas. Generally, these molecular properties have been estimated from bulk properties, but many assumptions are required. As a result, different literature values are employed for these essential molecular properties. Calculated molar volumes and excluded molecular areas are determined and tabulated for a variety of molecules. Molecular dimensions of molecules are important in the understanding of molecular exclusion as well as size and shape selectivity, diffusion, and adsorbent selection. Molecular dimensions can also be used in the determination of the effective catalytic pore size of a catalyst. Adsorption isotherms, on zeolites, (crystalline mineral oxides) and amorphous solids, can be analyzed with the Multiple Equilibrium Analysis (MEA) description of adsorption. The MEA produces equilibrium constants (Ki), capacities (ni), and thermodynamic parameters (enthalpies, ΔHi, and entropies, ΔSi) of adsorption for each process. Pore volumes and accessible surface areas are calculated from the process capacities. Adsorption isotherms can also be predicted for existing and new adsorbate-adsorbent systems with the MEA. The results show that MEA has the potential of becoming a standard characterization method for microporous solids that will lead to an increased understanding of their behavior in gas

  3. 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

  4. Toward Accurate Adsorption Energetics on Clay Surfaces

    PubMed Central

    2016-01-01

    Clay minerals are ubiquitous in nature, and the manner in which they interact with their surroundings has important industrial and environmental implications. Consequently, a molecular-level understanding of the adsorption of molecules on clay surfaces is crucial. In this regard computer simulations play an important role, yet the accuracy of widely used empirical force fields (FF) and density functional theory (DFT) exchange-correlation functionals is often unclear in adsorption systems dominated by weak interactions. Herein we present results from quantum Monte Carlo (QMC) for water and methanol adsorption on the prototypical clay kaolinite. To the best of our knowledge, this is the first time QMC has been used to investigate adsorption at a complex, natural surface such as a clay. As well as being valuable in their own right, the QMC benchmarks obtained provide reference data against which the performance of cheaper DFT methods can be tested. Indeed using various DFT exchange-correlation functionals yields a very broad range of adsorption energies, and it is unclear a priori which evaluation is better. QMC reveals that in the systems considered here it is essential to account for van der Waals (vdW) dispersion forces since this alters both the absolute and relative adsorption energies of water and methanol. We show, via FF simulations, that incorrect relative energies can lead to significant changes in the interfacial densities of water and methanol solutions at the kaolinite interface. Despite the clear improvements offered by the vdW-corrected and the vdW-inclusive functionals, absolute adsorption energies are often overestimated, suggesting that the treatment of vdW forces in DFT is not yet a solved problem. PMID:27917256

  5. Adsorption of quinolone, tetracycline, and penicillin antibiotics from aqueous solution using activated carbons: Review.

    PubMed

    Ahmed, Muthanna J

    2017-03-01

    Antibiotics, an important type of pharmaceutical pollutant, have attracted many researchers to the study of their removal from aqueous solutions. Activated carbon (AC) has been widely used as highly effective adsorbent for antibiotics because of its large specific surface area, high porosity, and favorable pore size distribution. In this article, the adsorption performance of AC towards three major types of antibiotics such as tetracyclines, quinolones, and penicillins were reviewed. According to collected data, maximum adsorption capacities of 1340.8, 638.6, and 570.4mg/g were reported for tetracyclines, quinolones, and penicillins, respectively. The values of 1/n for Freundlich isotherm were less than unity, suggesting that the adsorption was nonlinear and favorable. Adsorption kinetics followed closely the pseudo-second-order model and analysis using the Weber-Morris model revealed that the intra-particle diffusion was not the only rate controlling step. AC adsorption demonstrated superior performance for all selected drugs, thus being efficient technology for treatment of these pollutants.

  6. 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.

  7. Dual-porosity Mn2O3 cubes for highly efficient dye adsorption.

    PubMed

    Shao, Yongjiu; Ren, Bin; Jiang, Hanmei; Zhou, Bingjie; Lv, Liping; Ren, Jingzheng; Dong, Lichun; Li, Jing; Liu, Zhenfa

    2017-03-08

    Dual-porosity materials containing both macropores and mesopores are highly desired in many fields. In this work, we prepared dual-porosity Mn2O3 cube materials with large-pore mesopores, in which, macropores are made by using carbon spheres as the hard templates, while the mesopores are produced via a template-free route. The attained dual-porosity Mn2O3 materials have 24nm of large-pore mesopores and 700nm of macropores. Besides, the achieved materials own cubic morphologies with particle sizes as large as 6.0μm, making them separable in the solution by a facile natural sedimentation. Dye adsorption measurements reveal that the dual-porosity materials possess a very high maximum adsorption capacity of 125.6mg/g, much larger than many reported materials. Particularly, the adsorbents can be recycled and the dye removal efficiency can be well maintained at 98% after four cycles. Adsorption isotherm and kinetics show that the Langmuir model and the pseudo-second-order kinetics model can well describe the adsorption process of Congo Red on the dual-porosity Mn2O3 cube materials. In brief, the reported dual-porosity Mn2O3 demonstrates a good example for controlled preparation of dual-porosity materials with large-pore mesopores, and the macropore-mesopore dual-porosity distribution is good for mass transfer in dye adsorption application.

  8. Adsorption equilibrium and kinetics for SO2, NO, CO2 on zeolites FAU and LTA.

    PubMed

    Yi, Honghong; Deng, Hua; Tang, Xiaolong; Yu, Qiongfen; Zhou, Xuan; Liu, Haiyan

    2012-02-15

    In order to develop a single-step process for removing SO(2), NO, CO(2) in flue gas simultaneously by co-adsorption method. Pure component adsorption equilibrium and kinetics of SO(2), NO, and CO(2) on zeolite NaY, NaX, CaA were obtained respectively. Equilibrium data were analyzed by equilibrium model and Henry's law constant. The results suggest that Adsorption affinity follows the trend SO(2)>CO(2)>NO for the same adsorbent. Zeolite with stronger polar surface is a more promising adsorbent candidate. Kinetics behavior was investigated using the breakthrough curve method. The overall mass transfer coefficient and diffusivity factor were determined by a linear driving force model. The results are indicative of micropore diffusion controlling mechanism. NaY zeolite has the minimum resistance of mass transfer duo to the wide pore distribution and large pore amount. CaA zeolite exhibits the highest spatial hindered effect. Finally, co-adsorption effect of SO(2), NO, and CO(2) were investigated by multi-components breakthrough method. SO(2) and NO may form new adsorbed species, however, CO(2) presents a fast breakthrough. Chemical adsorption causes SO(2) transforms to SO(4)(2-), however, element N and C are not detected in adsorbed zeolites.

  9. Isotherms for adsorption of cellobiohydrolase I and II from Trichoderma reesei on microcrystalline cellulose

    SciTech Connect

    Medve, J.; Tjerneld, F.; Stahlberg, J.

    1997-04-01

    Adsorption to microcrystalline cellulose (Avicel) of pure cellobiohydrolase I and II (CBH I and CBH II) from Trichoderma reesei has been studied. Adsorption isotherms of the enzymes were measured at 4{degree}C using CBH I and CBH II alone and in reconstituted equimolar mixtures. Several models (Langmuir, Freundlich, Temkin, Jovanovic) were tested to describe the experimental adsorption isotherms. The isotherms did not follow the basic (one site) Langmuir equation that has often been used to describe adsorption isotherms of cellulases; correlation coefficients (R{sup 2}) were only 0.926 and 0.947, for CBH I and II, respectively. The experimental isotherms were best described by a model of Langmuir type with two adsorption sites and by a combined Langmuir-Freundlich model (analogous to the Hill equation); using these models the correlation coefficients were in most cases higher than 0.995. Apparent binding parameters derived from the two sites Langmuir model indicated stronger binding of CBH II compared to CBH I; the distribution coefficients were 20.7 and 3.7 L/g for the two enzymes, respectively. The binding capacity was higher for CBH I than for CBH II. The isotherms when analyzed with the combined model indicated presence of unequal binding sites on cellulose and/or negative cooperativity in the binding of the enzyme molecules. 39 refs., 3 figs., 3 tabs.

  10. Molecular dynamics simulations of H2 adsorption in tetramethyl ammonium lithium phthalocyanine crystalline structures.

    PubMed

    Lamonte, Kevin; Gómez Gualdrón, Diego A; Cabrales-Navarro, Fredy A; Scanlon, Lawrence G; Sandi, Giselle; Feld, William; Balbuena, Perla B

    2008-12-11

    Tetramethyl ammonium lithium phthalocyanine is explored as a potential material for storage of molecular hydrogen. Density functional theory calculations are used to investigate the molecular structure and the dimer conformation. Additional scans performed to determine the interactions of a H2 molecule located at various distances from the molecular sites are used to generate a simple force field including dipole-induced-dipole interactions. This force field is employed in molecular dynamics simulations to calculate adsorption isotherms at various pressures. The regions of strongest adsorption are quantified as functions of temperature, pressure, and separation between molecules in the adsorbent phase, and compared to the regions of strongest binding energy as given by the proposed force field. It is found that the total adsorption could not be predicted only from the spatial distribution of the strongest binding energies; the available volume is the other contributing factor even if the volume includes regions of much lower binding energy. The results suggest that the complex anion is primarily involved in the adsorption process with molecular hydrogen, whereas the cation serves to provide access for hydrogen adsorption in both sides of the anion molecular plane, and spacing between the planes.

  11. 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.

  12. Modeling water adsorption in carbon micropores: study of water in carbon molecular sieves.

    PubMed

    Rutherford, S W

    2006-01-17

    Measurements of water adsorption equilibrium in a carbon molecular sieve are undertaken in order to gain insight into the nature of water adsorption in carbon micropores. The measurements are taken at low concentrations to emphasize the role of oxygen-containing functional groups in the adsorption of water. Comparisons are made with previously published water adsorption data at higher concentrations to provide a data set spanning a wide range of loading. The assembled data set provides an opportunity for comparison of various theories for prediction of water adsorption in carbon micropores. Shortcomings of current theories are outlined, and an analytical theory that is free of these deficiencies is proposed in this investigation. With the consideration of micropore volume and pore size distribution, the experimental data and proposed isotherm model are consistent with previous studies of Takeda carbon molecular sieves. Also investigated is the uptake kinetics of water, which is characterized by a Fickian diffusion mechanism. The Maxwell-Stefan formulation is applied to characterize the dependence of the diffusional mobility upon loading.

  13. The adsorption characteristics of heavy metals by various particle sizes of MSWI bottom ash.

    PubMed

    Shim, Young-Sook; Kim, Young-Keun; Kong, Sung-Ho; Rhee, Seung-Whee; Lee, Woo-Keun

    2003-01-01

    The incineration rate of municipal solid waste (MSW) has been increased because of difficulty in securing a proper disposal site for MSW in Korea. The advantage of incineration is reduction of the volume of waste; however, significant amounts of bottom ash and fly ash were generated in the incineration process. Their treatment has attracted growing interest because of the potential toxicity of hazardous heavy metals. Generally, heavy metals are less released from bottom ash than from fly ash. In this study the adsorption characteristics of heavy metals were investigated using various particle sizes of MSWI bottom ash. Since bottom ash has a broad particle size distribution, it was sieved to size classes of +20, -20, -48, -80, -100 mesh. Cation exchange capacity (CEC) was analyzed by the ammonium acetate method to evaluate the potential as an adsorbent. The CEC values and surface areas increase as the range of particle size becomes finer. The adsorption experiment was conducted using synthetic (Cu and Ni) and plating rinse water as a function of reaction time (10-180 min), liquid/solid ratio (2-100) and particle size (+20 to -100 mesh), respectively. The adsorption rate increased with decreasing particle size and with increasing liquid/solid ratio; however, the removal efficiency of Cu was higher than that of Ni. In the case of plating rinse water, the adsorption rate decreased sharply at high liquid/solid ratio, and it showed over 80% of adsorption rates for Cu and Ni at an initial pH of 3.

  14. 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

  15. Breakthrough curve analysis of pressure swing adsorption for hydrogen isotope separation

    SciTech Connect

    Kotoh, K.; Tanaka, M.; Sakamoto, T.; Nakamura, Y.; Asakura, Y.; Uda, T.; Sugiyama, T.

    2008-07-15

    For the purpose of developing an effective system for hydrogen isotope separation, we have been studying the adsorption-desorption dynamic behavior of hydrogen and deuterium in a packed-bed column with synthetic zeolites, aimed at applying the pressure swing adsorption process. The adsorption behavior of molecules in the packed-bed is reflected in the breakthrough curves. To understand the characteristic behaviors of hydrogen isotopes in the packed-bed, we carried out breakthrough experiments in a conventional adsorption process and in a practical process following sequential processes alternating between adsorption and desorption. From the former experiments, the results were obtained that the overall mass transfer was influenced by longitudinal dispersion relating to the superficial velocity and that the process governing the mass transfer within adsorbents was diffusion in the macro-pores of pellets. In the latter experiments, unique profile breakthrough curves were observed. These curves can be described with the numerical simulation assuming the initial distributions in a packed-bed. (authors)

  16. Removal of Heavy Metals by Adsorption onto Activated Carbon Derived from Pine Cones of Pinus roxburghii.

    PubMed

    Saif, Muhammad Jawwad; Zia, Khalid Mahmood; Fazal-ur-Rehman; Usman, Muhammad; Hussain, Abdullah Ijaz; Chatha,