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Sample records for adsorption energy increases

  1. Computation of Adsorption Energies of Some Interstellar Species

    NASA Astrophysics Data System (ADS)

    Sil, Milan; Chakrabarti, Sandip Kumar; Das, Ankan; Majumdar, Liton; Gorai, Prasanta; Etim, Emmanuel; Arunan, Elangannan

    2016-07-01

    Adsorption energies of surface species are most crucial for chemical complexity of interstellar grain mantle. Aim of this work is to study the variation of the adsorption energies depending upon the nature of adsorbent. We use silicate and carbonaceous grains for the absorbents. For silicate grains, we use very simple crystalline ones, namely, Enstatite (MgSiO_3)_n, Ferrosilite (FeSiO_3)_n, Forsterite (Mg_2SiO_4)_n and Fayalite (Fe_2SiO_4)_n. We use n=1, 2, 4, 8 to study the variation of adsorption energies with the increase in cluster size. For carbonaceous grain, we use Coronene (polyaromatic hydrocarbon surface). Adsorption energy of all these species are calculated by means of quantum chemical calculation using self consistent density functional theory (DFT). MPWB1K hybrid meta-functional is employed since it has been proven useful to study the systems with weak interactions such as van der Waals interactions. Optimization are also carried out with MPWB1K/6-311g(d) and MPWB1K/6311g(d,p) and a comparison of adsorption energies are discussed for these two different basis sets. We use crystalline structure of the adsorbent. The adsorbate is placed in the different site of the grain with a suitable distance. The energy of adsorption for a species on the grain surface is defined as follows: E_a_d_s = E_s_s - (E_s_u_r_f_a_c_e + E_s_p_e_c_i_e_s), where E_a_d_s is the adsorption energy, E_s_s is the optimized energy for species placed in a suitable distance from the grain surface, E_s_u_r_f_a_c_e and E_s_p_e_c_i_e_s respectively are the optimized energies of the surface and species separately.

  2. Pulmonary surfactant adsorption is increased by hyaluronan or polyethylene glycol.

    PubMed

    Taeusch, H William; Dybbro, Eric; Lu, Karen W

    2008-04-01

    In acute lung injuries, inactivating agents may interfere with transfer (adsorption) of pulmonary surfactants to the interface between air and the aqueous layer that coats the interior of alveoli. Some ionic and nonionic polymers reduce surfactant inactivation in vitro and in vivo. In this study, we tested directly whether an ionic polymer, hyaluronan, or a nonionic polymer, polyethylene glycol, enhanced adsorption of a surfactant used clinically. We used three different methods of measuring adsorption in vitro: a modified pulsating bubble surfactometer; a King/Clements device; and a spreading trough. In addition we measured the effects of both polymers on surfactant turbidity, using this assay as a nonspecific index of aggregation. We found that both hyaluronan and polyethylene glycol significantly increased the rate and degree of surfactant material adsorbed to the surface in all three assays. Hyaluronan was effective in lower concentrations (20-fold) than polyethylene glycol and, unlike polyethylene glycol, hyaluronan did not increase apparent aggregation of surfactant. Surfactant adsorption in the presence of serum was also enhanced by both polymers regardless of whether hyaluronan or polyethylene glycol was included with serum in the subphase or added to the surfactant applied to the surface. Therefore, endogenous polymers in the alveolar subphase, or exogenous polymers added to surfactant used as therapy, may both be important for reducing inactivation of surfactant that occurs with various lung injuries. PMID:18065212

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

    NASA Astrophysics Data System (ADS)

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

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

  4. Methane Adsorption on Aggregates of Fullerenes: Site-Selective Storage Capacities and Adsorption Energies

    PubMed Central

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

    2013-01-01

    Methane adsorption on positively charged aggregates of C60 is investigated by both mass spectrometry and computer simulations. Calculated adsorption energies of 118–281 meV are in the optimal range for high-density storage of natural gas. Groove sites, dimple sites, and the first complete adsorption shells are identified experimentally and confirmed by molecular dynamics simulations, using a newly developed force field for methane–methane and fullerene–methane interaction. The effects of corrugation and curvature are discussed and compared with data for adsorption on graphite, graphene, and carbon nanotubes. PMID:23744834

  5. Peptide adsorption on the hydrophobic surface: A free energy perspective

    NASA Astrophysics Data System (ADS)

    Sheng, Yuebiao; Wang, Wei; Chen, P.

    2011-05-01

    Protein adsorption is a very attractive topic which relates to many novel applications in biomaterials, biotechnology and nanotechnology. Ionic complementary peptides are a group of novel nano-biomaterials with many biomedical applications. In this work, molecular dynamics simulations of the ionic-complementary peptide EAK16-II on a hydrophobic graphite surface were performed under neutral, acidic and basic solution conditions. Adsorption free energy contour maps were obtained by analyzing the dynamical trajectories. Hydrophobic interactions were found to govern the adsorption of the first peptide molecule, and both hydrophobic and electrostatic interactions contributed to the adsorption of the second peptide molecule. Especially under acidic and basic solution conditions, interplay existed among chain-chain hydrophobic, chain-surface hydrophobic and chain-chain electrostatic interactions during the adsorption of the second peptide molecule. Non-charged residues were found to lie on the graphite surface, while charged residue side-chains oriented towards the solution after the peptide deposited on the surface. These results provide a basis for understanding peptide adsorption on the hydrophobic surface under different solution conditions, which is useful for novel applications such as bioactive implant devices and drug delivery material design.

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

    PubMed

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

    2016-01-01

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

  7. Combined adsorption-UF process increases TOC removal

    SciTech Connect

    Chang, Y.J.; Choo, K.H.; Benjamin, M.M.; Reiber, S.

    1998-05-01

    Addition of heated iron oxide particles (HIOPs) as adsorbents to the feedwater of an ultrafiltration (UF) membrane system significantly increased removal of dissolved organic carbon (DOC) and reduced trihalomethane formation potential (THMFP). Treatment by the HIOP-UF process met the TOC removal criteria set by the enhanced coagulation provision of the proposed Disinfectants/Disinfection By-products Rule in all 16 water sources tested, even though those criteria were not met by enhanced coagulation with alum or ferric sulfate in many of the water sources. At pH 6.5 and for the operational conditions studied, 40--75 percent of the DOC was removed; this percentage might be increased at lower pH or a higher HIOP dosage. THMFP was reduced even more (approximately 5--10 percent more) than DOC. Although HIOPs tended to reduce membrane fouling, both soft water with extremely high DOC concentrations and hard, alkaline water with moderate DOC concentrations fouled the HIOP-UF system. Fouling was less severe at lower pH values.

  8. Surface free energy analysis of adsorbents used for radioiodine adsorption

    NASA Astrophysics Data System (ADS)

    González-García, C. M.; Román, S.; González, J. F.; Sabio, E.; Ledesma, B.

    2013-10-01

    In this work, the surface free energy of biomass-based activated carbons, both fresh and impregnated with triethylenediamine, has been evaluated. The contribution of Lifshitz van der Waals components was determined by the model proposed by van Oss et al. The results obtained allowed predicting the most probable configurations of the impregnant onto the carbon surface and its influence on the subsequent adsorption of radioactive methyl iodide.

  9. New Carbon-Based Porous Materials with Increased Heats of Adsorption for Hydrogen Storage

    SciTech Connect

    Snurr, Randall Q.; Hupp, Joseph T.; Kanatzidis, Mercouri G.; Nguyen, SonBinh T.

    2014-11-03

    . Only after modeling suggested record-breaking hydrogen uptake at 77 K did we proceed to synthesize, characterize, and test the material, ultimately yielding experimental results that agreed closely with predictions that were made before the material was synthesized. We also synthesized, characterized, and computationally simulated the behavior of two new materials displaying the highest experimental Brunauer−Emmett−Teller (BET) surface areas of any porous materials reported to date (∼7000 m2/g). Key to evacuating the initially solvent-filled materials without pore collapse, and thereby accessing the ultrahigh areas, was the use of a supercritical CO2 activation technique developed by our team. In our efforts to increase the hydrogen binding energy, we developed the first examples of “zwitterionic” metal-organic frameworks (MOFs). The two structures feature zwitterionic characteristics arising from N-heterocyclic azolium groups in the linkers and negatively charged Zn2(CO2)5 nodes. These groups interact strongly with the H2 quadrupole. High initial isosteric heats of adsorption for hydrogen were measured at low H2 loading. Simulations were used to determine the H2 binding sites, and results were compared with inelastic neutron scattering. In addition to MOFs, the project produced a variety of related materials known as porous organic frameworks (POFs), including robust catechol-functionalized POFs with tunable porosities and degrees of functionalization. Post-synthesis metalation was readily carried out with a wide range of metal precursors (CuII, MgII, and MnII salts and complexes), resulting in metalated POFs with enhanced heats of hydrogen adsorption compared to the starting nonmetalated materials. Isosteric heats of adsorption as high as 9.6 kJ/mol were observed, compared to typical values around 5 kJ/mol in unfunctionalized MOFs and POFs. Modeling played an important role throughout the project. For example, we used molecular simulations to determine that

  10. Benchmark Experimental Data Set and Assessment of Adsorption Free Energy for Peptide-Surface Interactions

    PubMed Central

    Wei, Yang; Latour, Robert A.

    2009-01-01

    With the increasing interest in protein adsorption in fields ranging from bionanotechnology to biomedical engineering, there is a growing need to understand protein-surface interactions at a fundamental level, such as the interaction between individual amino acid residues of a protein and functional groups presented by a surface. However, relatively little data are available that experimentally provide a quantitative, comparative measure of these types of interactions. To address this deficiency, the objective of this study was to generate a database of experimentally measured standard state adsorption free energy (ΔGoads) values for a wide variety of amino acid residue-surface interactions using a host-guest peptide and alkanethiol self-assembled monolayers (SAMs) with polymer-like functionality as the model system. The host-guest amino acid sequence was synthesized in the form of TGTG-X-GTGT where G & T are glycine and threonine amino acid residues and X represents a variable residue. In this paper, we report ΔGoads values for the adsorption of twelve different types of the host-guest peptides on a set of nine different SAM surfaces, for a total of 108 peptide-surface systems. The ΔGoads values for these 108 peptide-surface combinations show clear trends in adsorption behavior that are dependent on both peptide composition and surface chemistry. These data provide a benchmark experimental data set from which fundamental interactions that govern peptide and protein adsorption behavior can be better understood and compared. PMID:19432493

  11. Reduced sulfentrazone phytotoxicity through increased adsorption and anionic species in biochar-amended soils.

    PubMed

    Liu, Kailin; Yu, Bingqi; Luo, Kun; Liu, Xiangying; Bai, Lianyang

    2016-05-01

    Burning straw in the field is a common agricultural practice. The effects of adding biochar derived from rice straw to soils on the phytotoxicity of sulfentrazone to Oryza sativa L. were observed. Overall, when 1 % biochar was added to three different soils, the phytotoxicity of sulfentrazone to O. sativa L. decreased, and the concentration that inhibits growth by 50 % (IC50) increased by 1.4 to 7.6 times. To illuminate the influencing mechanisms, the changes in sulfentrazone adsorption to the soil, the soil pH, and the bioavailable sulfentrazone extracted from the soil solution using hollow fiber-based liquid-phase microextraction were studied. The Freundlich constant (K f ) of sulfentrazone to the soil increased 1.5 to 25 times relative to the K f in the three unamended soils, and the soil pH increased by 0.36 to 1.36 units resulted in a fraction of dissociated sulfentrazone increased by 10.2-17.4 %. In addition, the average concentrations of sulfentrazone in the three unamended soil solutions were 1.3-6.1 times relative to those in the three biochar-amended soil solutions. These results suggest that the sulfentrazone adsorption and soil pH increased when soils were amended with biochar, which decreased the bioavailable concentrations and reduced its phytotoxicity to O. sativa L. PMID:26865479

  12. An improved single crystal adsorption calorimeter for determining gas adsorption and reaction energies on complex model catalysts

    NASA Astrophysics Data System (ADS)

    Fischer-Wolfarth, Jan-Henrik; Hartmann, Jens; Farmer, Jason A.; Flores-Camacho, J. Manuel; Campbell, Charles T.; Schauermann, Swetlana; Freund, Hans-Joachim

    2011-02-01

    A new ultrahigh vacuum microcalorimeter for measuring heats of adsorption and adsorption-induced surface reactions on complex single crystal-based model surfaces is described. It has been specifically designed to study the interaction of gaseous molecules with well-defined model catalysts consisting of metal nanoparticles supported on single crystal surfaces or epitaxial thin oxide films grown on single crystals. The detection principle is based on the previously described measurement of the temperature rise upon adsorption of gaseous molecules by use of a pyroelectric polymer ribbon, which is brought into mechanical/thermal contact with the back side of the thin single crystal. The instrument includes (i) a preparation chamber providing the required equipment to prepare supported model catalysts involving well-defined nanoparticles on clean single crystal surfaces and to characterize them using surface analysis techniques and in situ reflectivity measurements and (ii) the adsorption/reaction chamber containing a molecular beam, a pyroelectric heat detector, and calibration tools for determining the absolute reactant fluxes and adsorption heats. The molecular beam is produced by a differentially pumped source based on a multichannel array capable of providing variable fluxes of both high and low vapor pressure gaseous molecules in the range of 0.005-1.5 × 1015 molecules cm-2 s-1 and is modulated by means of the computer-controlled chopper with the shortest pulse length of 150 ms. The calorimetric measurements of adsorption and reaction heats can be performed in a broad temperature range from 100 to 300 K. A novel vibrational isolation method for the pyroelectric detector is introduced for the reduction of acoustic noise. The detector shows a pulse-to-pulse standard deviation ≤15 nJ when heat pulses in the range of 190-3600 nJ are applied to the sample surface with a chopped laser. Particularly for CO adsorption on Pt(111), the energy input of 15 nJ (or 120 nJ cm

  13. 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.

  14. An improved single crystal adsorption calorimeter for determining gas adsorption and reaction energies on complex model catalysts.

    PubMed

    Fischer-Wolfarth, Jan-Henrik; Hartmann, Jens; Farmer, Jason A; Flores-Camacho, J Manuel; Campbell, Charles T; Schauermann, Swetlana; Freund, Hans-Joachim

    2011-02-01

    A new ultrahigh vacuum microcalorimeter for measuring heats of adsorption and adsorption-induced surface reactions on complex single crystal-based model surfaces is described. It has been specifically designed to study the interaction of gaseous molecules with well-defined model catalysts consisting of metal nanoparticles supported on single crystal surfaces or epitaxial thin oxide films grown on single crystals. The detection principle is based on the previously described measurement of the temperature rise upon adsorption of gaseous molecules by use of a pyroelectric polymer ribbon, which is brought into mechanical∕thermal contact with the back side of the thin single crystal. The instrument includes (i) a preparation chamber providing the required equipment to prepare supported model catalysts involving well-defined nanoparticles on clean single crystal surfaces and to characterize them using surface analysis techniques and in situ reflectivity measurements and (ii) the adsorption∕reaction chamber containing a molecular beam, a pyroelectric heat detector, and calibration tools for determining the absolute reactant fluxes and adsorption heats. The molecular beam is produced by a differentially pumped source based on a multichannel array capable of providing variable fluxes of both high and low vapor pressure gaseous molecules in the range of 0.005-1.5 × 10(15) molecules cm(-2) s(-1) and is modulated by means of the computer-controlled chopper with the shortest pulse length of 150 ms. The calorimetric measurements of adsorption and reaction heats can be performed in a broad temperature range from 100 to 300 K. A novel vibrational isolation method for the pyroelectric detector is introduced for the reduction of acoustic noise. The detector shows a pulse-to-pulse standard deviation ≤15 nJ when heat pulses in the range of 190-3600 nJ are applied to the sample surface with a chopped laser. Particularly for CO adsorption on Pt(111), the energy input of 15 n

  15. 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.

  16. Adsorption of Water Monomer and Clusters on Platinum(111) Terrace and Related Steps and Kinks I. Configurations, Energies, and Hydrogen Bonding

    SciTech Connect

    Arnadottir, Liney; Stuve, Eric M.; Jonsson, Hannes

    2010-10-01

    Adsorption and rotation of water monomer, dimer, and trimer on the (111) terrace, (221) and (322) stepped, and (763) and (854) kinked surfaces of platinum were studied by density functional theory calculations using the PW91 approximation to the energy functional. On the (111) terrace, water monomer and the donor molecule of the dimer and trimer adsorb at atop sites. The permolecule adsorption energies of the monomer, dimer, and trimer are 0.30, 0.45, and 0.48 eV, respectively. Rotation of monomers, dimers, and trimers on the terrace is facile with energy barriers of 0.02 eV or less. Adsorption on steps and kinks is stronger than on the terrace, as evidenced by monomer adsorption energies of 0.46 to 0.55 eV. On the (221) stepped surface the zigzag extended configuration is most stable with a per-molecule adsorption energy of 0.57 eV. On the (322) stepped surface the dimer, two configurations of the trimer, and the zigzag configuration have similar adsorption energies of 0.55 ± 0.02 eV. Hydrogen bonding is strongest in the dimer and trimer adsorbed on the terrace, with respective energies of 0.30 and 0.27 eV, and accounts for their increased adsorption energies relative to the monomer. Hydrogen bonding is weak to moderate for adsorption at steps, with energies of 0.04 to 0.15 eV, as the much stronger water-metal interactions inhibit adsorption geometries favorable to hydrogen bonding. Correlations of hydrogen bond angles and energies with hydrogen bond lengths are presented. On the basis of these DFT/PW91 results, a model for water cluster formation on the Pt(111) surface can be formulated where kink sites nucleate chains along the top of step edges, consistent with the experimental findings of Morgenstern et al., Phys. Rev. Lett., 77 (1996) 703.

  17. Scaling Properties of Adsorption Energies for Hydrogen-Containing Molecules on Transition-Metal Surfaces

    NASA Astrophysics Data System (ADS)

    Abild-Pedersen, F.; Greeley, J.; Studt, F.; Rossmeisl, J.; Munter, T. R.; Moses, P. G.; Skúlason, E.; Bligaard, T.; Nørskov, J. K.

    2007-07-01

    Density functional theory calculations are presented for CHx, x=0,1,2,3, NHx, x=0,1,2, OHx, x=0,1, and SHx, x=0,1 adsorption on a range of close-packed and stepped transition-metal surfaces. We find that the adsorption energy of any of the molecules considered scales approximately with the adsorption energy of the central, C, N, O, or S atom, the scaling constant depending only on x. A model is proposed to understand this behavior. The scaling model is developed into a general framework for estimating the reaction energies for hydrogenation and dehydrogenation reactions.

  18. Optimization of adsorption processes for climate control and thermal energy storage

    SciTech Connect

    Narayanan, S; Yang, S; Kim, H; Wang, EN

    2014-10-01

    Adsorption based heat-pumps have received significant interest owing to their promise of higher efficiencies and energy savings when coupled with waste heat and solar energy compared to conventional heating and cooling systems. While adsorption systems have been widely studied through computational analysis and experiments, general design guidelines to enhance their overall performance have not been proposed. In this work, we identified conditions suitable for the maximum utilization of the adsorbent to enhance the performance of both intermittent as well as continuously operating adsorption systems. A detailed computational model was developed based on a general framework governing adsorption dynamics in a single adsorption layer and pellet. We then validated the computational analysis using experiments with a model system of zeolite 13X-water for different operating conditions. A dimensional analysis was subsequently carried out to optimize adsorption performance for any desired operating condition, which is determined by the choice of adsorbent-vapor pair, adsorption duration, operational pressure, intercrystalline porosity, adsorbent crystal size, and intracrystalline vapor diffusivity. The scaling analysis identifies the critical dimensionless parameters and provides a simple guideline to determine the most suitable geometry for the adsorbent particles. Based on this selection criterion, the computational model was used to demonstrate maximum utilization of the adsorbent for any given operational condition. By considering a wide range of parametric variations for performance optimization, these results offer important insights for designing adsorption beds for heating and cooling systems. (C) 2014 Elsevier Ltd. All rights reserved.

  19. Screened Hybrid Exact Exchange Schemes to Adsorption Energies on Perovskite Oxides

    NASA Astrophysics Data System (ADS)

    Santos, Elton; Vojvodic, Aleksandra; Norskov, Jens K.

    The bond formation between an oxide surface and oxygen, which is one of the important intermediates for oxygen evolution reaction, is investigated using hybrid functionals. We show that there exists a linear correlation between the adsorption energies of oxygen on LaMO3 (M =Sc-Cu) oxides at hybrid calculations to those computed using semilocal density functionals through the magnetic properties of the bulk phase. The energetics of the spin-polarized surfaces follow the same trend as corresponding bulk systems, which can be treated at a much lower computational cost. The difference in adsorption energy due to magnetism is linearly correlated to the magnetization energy of bulk, i.e., the energy difference between the spin-polarized and the non spin-polarized solutions. This suggests that one could estimate the correction to the semilocal density functional adsorption energies directly from the hybrid bulk magnetization energy.

  20. Correlation between oxygen adsorption energy and electronic structure of transition metal macrocyclic complexes

    SciTech Connect

    Liu, Kexi; Lei, Yinkai; Wang, Guofeng

    2013-11-28

    Oxygen adsorption energy is directly relevant to the catalytic activity of electrocatalysts for oxygen reduction reaction (ORR). In this study, we established the correlation between the O{sub 2} adsorption energy and the electronic structure of transition metal macrocyclic complexes which exhibit activity for ORR. To this end, we have predicted the molecular and electronic structures of a series of transition metal macrocyclic complexes with planar N{sub 4} chelation, as well as the molecular and electronic structures for the O{sub 2} adsorption on these macrocyclic molecules, using the density functional theory calculation method. We found that the calculated adsorption energy of O{sub 2} on the transition metal macrocyclic complexes was linearly related to the average position (relative to the lowest unoccupied molecular orbital of the macrocyclic complexes) of the non-bonding d orbitals (d{sub z{sup 2}}, d{sub xy}, d{sub xz}, and d{sub yz}) which belong to the central transition metal atom. Importantly, our results suggest that varying the energy level of the non-bonding d orbitals through changing the central transition metal atom and/or peripheral ligand groups could be an effective way to tuning their O{sub 2} adsorption energy for enhancing the ORR activity of transition metal macrocyclic complex catalysts.

  1. Energy: Can We Meet the Increasing Demand?

    ERIC Educational Resources Information Center

    Roman, Harry T.

    2006-01-01

    Energy is the lifeblood of the United States. It powers its industries and keeps its economy humming. The nation's progress has relied on making energy abundantly available to support the growth of new ideas and products, and the issue of renewable energy is an increasingly important one. In this article, the author discusses some of the basics of…

  2. Volumetric Interpretation of Protein Adsorption: Capacity Scaling with Adsorbate Molecular Weight and Adsorbent Surface Energy

    PubMed Central

    Parhi, Purnendu; Golas, Avantika; Barnthip, Naris; Noh, Hyeran; Vogler, Erwin A.

    2009-01-01

    Silanized-glass-particle adsorbent capacities are extracted from adsorption isotherms of human serum albumin (HSA, 66 kDa), immunoglobulin G (IgG, 160 kDa), fibrinogen (Fib, 341 kDa), and immunoglobulin M (IgM, 1000 kDa) for adsorbent surface energies sampling the observable range of water wettability. Adsorbent capacity expressed as either mass-or-moles per-unit-adsorbent-area increases with protein molecular weight (MW) in a manner that is quantitatively inconsistent with the idea that proteins adsorb as a monolayer at the solution-material interface in any physically-realizable configuration or state of denaturation. Capacity decreases monotonically with increasing adsorbent hydrophilicity to the limit-of-detection (LOD) near τo = 30 dyne/cm (θ~65o) for all protein/surface combinations studied (where τo≡γlvocosθ is the water adhesion tension, γlvo is the interfacial tension of pure-buffer solution, and θ is the buffer advancing contact angle). Experimental evidence thus shows that adsorbent capacity depends on both adsorbent surface energy and adsorbate size. Comparison of theory to experiment implies that proteins do not adsorb onto a two-dimensional (2D) interfacial plane as frequently depicted in the literature but rather partition from solution into a three-dimensional (3D) interphase region that separates the physical surface from bulk solution. This interphase has a finite volume related to the dimensions of hydrated protein in the adsorbed state (defining “layer” thickness). The interphase can be comprised of a number of adsorbed-protein layers depending on the solution concentration in which adsorbent is immersed, molecular volume of the adsorbing protein (proportional to MW), and adsorbent hydrophilicity. Multilayer adsorption accounts for adsorbent capacity over-and-above monolayer and is inconsistent with the idea that protein adsorbs to surfaces primarily through protein/surface interactions because proteins within second (or higher

  3. Phenolic resin-based porous carbons for adsorption and energy storage applications

    NASA Astrophysics Data System (ADS)

    Wickramaratne, Nilantha P.

    The main objective of this dissertation research is to develop phenolic resin based carbon materials for range of applications by soft-templating and Stober-like synthesis strategies. Applications Studied in this dissertation are adsorption of CO2, bio-molecular and heavy metal ions, and energy storage devices. Based on that, our goal is to design carbon materials with desired pore structure, high surface area, graphitic domains, incorporated metal nanoparticles, and specific organic groups and heteroatoms. In this dissertation the organic-organic self-assembly of phenolic resins and triblock copolymers under acidic conditions will be used to obtain mesoporous carbons/carbon composites and Stober-like synthesis involving phenolic resins under basic condition will be used to prepare polymer/carbon particles and their composites. The structure of this dissertation consists of an introductory chapter (Chapter 1) discussing the general synthesis of carbon materials, particularly the soft-templating strategy and Stober-like carbon synthesis. Also, Chapter 1 includes a brief outline of applications namely adsorption of CO2, biomolecule and heavy metal ions, and supercapacitors. Chapter 2 discusses the techniques used for characterization of the carbon materials studied. This chapter starts with nitrogen adsorption analysis, which is used to measure the specific surface area, pore volume, distribution of pore sizes, and pore width. In addition to nitrogen adsorption, powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution thermogravimetric analysis (HR-TGA), cyclic voltammetry (CV) and CHNS elemental analysis (EA) are mentioned too. Chapter 3 is focused on carbon materials for CO2 adsorption. There are different types of porous solid materials such as silicate, MOFs, carbons, and zeolites studied for CO2 adsorption. However, the carbon based materials are considered to be the best candidates for CO 2 adsorption to the industrial point of

  4. Scaling Relationships for Adsorption Energies of C2 Hydrocarbons on Transition Metal Surfaces

    SciTech Connect

    Jones, G

    2011-08-18

    Using density functional theory calculations we show that the adsorption energies for C{sub 2}H{sub x}-type adsorbates on transition metal surfaces scale with each other according to a simple bond order conservation model. This observation generalizes some recently recognized adsorption energy scaling laws for AH{sub x}-type adsorbates to unsaturated hydrocarbons and establishes a coherent simplified description of saturated as well as unsaturated hydrocarbons adsorbed on transition metal surfaces. A number of potential applications are discussed. We apply the model to the dehydrogenation of ethane over pure transition metal catalysts. Comparison with the corresponding full density functional theory calculations shows excellent agreement.

  5. Organophilic treatments of bentonite increase the adsorption of aflatoxin B1 and protect stem cells against cellular damage.

    PubMed

    Nones, Janaína; Nones, Jader; Poli, Anicleto; Trentin, Andrea Gonçalves; Riella, Humberto Gracher; Kuhnen, Nivaldo Cabral

    2016-09-01

    Bentonite clays exhibit high adsorptive capacity for contaminants, including aflatoxin B1 (AFB1), a mycotoxin responsible for causing severe toxicity in several species including pigs, poultry and man. Organophilic treatments is known to increase the adsorption capacity of bentonites, and the primary aim of this study was to evaluate the ability of Brazilian bentonite and two organic salts - benzalkonium chloride (BAC) and cetyltrimethylammonium bromide (CTAB) to adsorb AFB1. For this end, 2(2) factorial designs were used in order to analyze if BAC or CTAB was able to increase AFB1 adsorption when submitted in different temperature and concentration. Both BAC and CTAB treatment (at 30°C and 2% of salt concentration) were found to increase the adsorption of AFB1 significantly compared with untreated bentonite. After organophilic bentonite treatments with BAC or CTAB, a vibration of CH stretch (2850 and 2920cm(-1)) were detected. A frequency of the SiO stretch (1020 and 1090cm(-1)) was changed by intercalation of organic cation. Furthermore, the interlayer spacing of bentonite increases to 1.23nm (d001 reflection at 2θ=7.16) and 1.22 (d001 reflection at 2θ=7.22) after the addition of BAC and CTAB, respectively. Another aim of the study was to observe the effects of these two bentonite salts in neural crest stem cell cultures. The two materials that were created by organophilic treatments were not found to be toxic to stem cells. Furthermore the results indicate that the two materials tested may protect the neural crest stem cells against damage caused by AFB1. PMID:27281241

  6. The effect of ligand substitution and water co-adsorption on the adsorption dynamics and energy level matching of amino-phenyl acid dyes on TiO2.

    PubMed

    Manzhos, Sergei; Segawa, Hiroshi; Yamashita, Koichi

    2012-02-01

    We perform a comparative theoretical analysis of adsorption of dyes NK1 (2E,4E-2-cyano-5-(4-dimethylaminophenyl)penta-2,4-dienoic acid) and NK7 (2E,4E-2-cyano-5-(4-diphenylaminophenyl)penta-2,4-dienoic acid) on clean and water-covered anatase (101) surfaces of TiO(2). Ligand substitution away from the anchoring group changes the energy level matching between the dye's LUMO and the oxide's conduction band. Monodentate binding and bidentate binding configurations of the dyes to TiO(2) are found to have similar adsorption energies even though the injection from the bidentate mode is found to dominate. Water has a strong effect on adsorption, inducing deprotonation and affecting strongly and differently between the dyes the energy level matching, leading to a shut-off of the injection from NK7 of bidentate adsorption configuration. Ab initio molecular dynamics simulations show a strong effect of nuclear motion on energy levels, specifically, increasing the driving force for injection in the monodentate regime. PMID:22194034

  7. Protein adsorption to poly(ethylenimine)-modified Sepharose FF: VI. Partial charge neutralization drastically increases uptake rate.

    PubMed

    Zhao, Yangyang; Dong, Xiaoyan; Yu, Linling; Sun, Yan

    2016-01-01

    The adsorption and elution behaviors of bovine serum albumin (BSA) on poly(ethylenimine) (PEI)-grafted Sepharose FF resins were recently studied and a critical ionic capacity (cIC; 600 mmol/L) was found, above which the uptake rate increased drastically due to the occurrence of significant "chain delivery" effect. Moreover, above the cIC value, higher salt concentrations were required for protein elution due to the high charge density of the resins. In this work, we have reduced the charge density on the PEI chains of a PEI-grafted resin by neutralization of the amine groups with sodium acetate. PEI-modified resin with IC of 740 mmol/L (FF-PEI-L740, IC>cIC) was chosen as the starting material, and three resins with residual IC values of 660, 560 and 440 mmol/L (FF-PEI-R440) were obtained. The adsorption and chromatographic behaviors of these resins for BSA were investigated. It was found that, with IC decreasing from 740 to 440 mmol/L, the adsorption capacity kept almost unchanged; the effective protein diffusivity (De) also showed negligible variations as IC decreased from 740 to 560 mmol/L (De/D0=0.38 ± 0.04). However, it was interesting to observe a three-fold increase of the De value for FF-PEI-R440 (De/D0=1.23 ± 0.08). It is considered that the occurrence of the drastic uptake rate increase in FF-PEI-R440 was attributed to the decreased available binding sites for protein molecule, which led to the decrease of binding strength, thus facilitated the happenings of "chain delivery" effect of bound proteins. Besides, a study on the effect of ionic strength clarified that the lower the IC value, the higher the sensitivity of protein binding to salt concentration due to the easily screened electrostatic interactions at low surface charge densities. The ionic strength at the elution peak also decreased with decreasing IC in accordance with the salt sensitivity order. Column breakthrough studies demonstrated that the dynamic adsorption capacity of FF-PEI-R440 was

  8. Microgravimetric Analysis Method for Activation-Energy Extraction from Trace-Amount Molecule Adsorption.

    PubMed

    Xu, Pengcheng; Yu, Haitao; Li, Xinxin

    2016-05-01

    Activation-energy (Ea) value for trace-amount adsorption of gas molecules on material is rapidly and inexpensively obtained, for the first time, from a microgravimetric analysis experiment. With the material loaded, a resonant microcantilever is used to record in real time the adsorption process at two temperatures. The kinetic parameter Ea is thereby extracted by solving the Arrhenius equation. As an example, two CO2 capture nanomaterials are examined by the Ea extracting method for evaluation/optimization and, thereby, demonstrating the applicability of the microgravimetric analysis method. The achievement helps to solve the absence in rapid quantitative characterization of sorption kinetics and opens a new route to investigate molecule adsorption processes and materials. PMID:27100734

  9. Parameterization of an interfacial force field for accurate representation of peptide adsorption free energy on high-density polyethylene

    PubMed Central

    Abramyan, Tigran M.; Snyder, James A.; Yancey, Jeremy A.; Thyparambil, Aby A.; Wei, Yang; Stuart, Steven J.; Latour, Robert A.

    2015-01-01

    Interfacial force field (IFF) parameters for use with the CHARMM force field have been developed for interactions between peptides and high-density polyethylene (HDPE). Parameterization of the IFF was performed to achieve agreement between experimental and calculated adsorption free energies of small TGTG–X–GTGT host–guest peptides (T = threonine, G = glycine, and X = variable amino-acid residue) on HDPE, with ±0.5 kcal/mol agreement. This IFF parameter set consists of tuned nonbonded parameters (i.e., partial charges and Lennard–Jones parameters) for use with an in-house-modified CHARMM molecular dynamic program that enables the use of an independent set of force field parameters to control molecular behavior at a solid–liquid interface. The R correlation coefficient between the simulated and experimental peptide adsorption free energies increased from 0.00 for the standard CHARMM force field parameters to 0.88 for the tuned IFF parameters. Subsequent studies are planned to apply the tuned IFF parameter set for the simulation of protein adsorption behavior on an HDPE surface for comparison with experimental values of adsorbed protein orientation and conformation. PMID:25818122

  10. Adsorption and self-assembly of bio-organic molecules at model surfaces: A route towards increased complexity

    NASA Astrophysics Data System (ADS)

    Costa, Dominique; Pradier, Claire-Marie; Tielens, Frederik; Savio, Letizia

    2015-12-01

    Understanding the bio-physical-chemical interactions at nanostructured biointerfaces and the assembly mechanisms of so-called hybrid nano-composites is nowadays a key issue for nanoscience in view of the many possible applications foreseen. The contribution of surface science in this field is noteworthy since, using a bottom-up approach, it allows the investigation of the fundamental processes at the basis of complex interfacial phenomena and thus it helps to unravel the elementary mechanisms governing them. Nowadays it is well demonstrated that a wide variety of different molecular assemblies can form upon adsorption of small biomolecules at surfaces. The geometry of such self-organized structures can often be tuned by a careful control of the experimental conditions during the deposition process. Indeed an impressive number of studies exists (both experimental and - to a lesser extent - theoretical), which demonstrates the ability of molecular self-assembly to create different structural motifs in a more or less predictable manner, by tuning the molecular building blocks as well as the metallic substrate. In this frame, amino acids and small peptides at surfaces are key, basic, systems to be studied. The amino acids structure is simple enough to serve as a model for the chemisorption of biofunctional molecules, but their adsorption at surfaces has applications in surface functionalization, in enantiospecific catalysis, biosensing, shape control of nanoparticles or in emerging fields such as "green" corrosion inhibition. In this paper we review the most recent advances in this field. We shall start from the adsorption of amino acids at metal surfaces and we will evolve then in the direction of more complex systems, in the light of the latest improvements of surface science techniques and of computational methods. On one side, we will focus on amino acids adsorption at oxide surfaces, on the other on peptide adsorption both at metal and oxide substrates. Particular

  11. Water films on transition metal surfaces: A physical disclosure of adsorption energy

    NASA Astrophysics Data System (ADS)

    Revilla-López, Guillem; López, Nuria; Theoretical Heterogeneous Catalysis Group Team

    2014-03-01

    Our work reports novel physical models derived from DFT calculations including van der Waals forces for the adsorption of different water motifs: ice bilayer, √37 x √37-R 25.3° and rosette on transition metal surfaces. This energy decomposition scheme is obtained by analyzing the two driving energies of adsorption: water-water and water-metal interactions. The former explained by single water adsorption and the latter by ice resonance stabilization. These two magnitudes drive, to different extent, the adsorption of ice bilayer and √37 whereas rosette motif lacks the resonance contribution. The equations successfully reproduce and predict the experimental results for the wettability and the dissociation of water films on the fcc(111) and hcp(0001) facets of Pd, Pt, Ru Ir, Rh, Au, and Ag. So happens for the temperature of the hydrophobic/hydrophilic water film transition and for the effect of the surface roughness on it. Furthermore, the metastability and the wettability of other water films like √39 x √39-R 16.1° can be anticipated by the rationalization of their geometry and their dissociation state. The authors thank the ERC-2010-StG-258406 Bio2chem-d project, MINECO (CTQ2012-33826) and BSC-RES for supporting this work.

  12. Identical Binding Energies and Work Functions for Distinct Adsorption Structures: Olympicenes on the Cu(111) Surface.

    PubMed

    Liu, Wei; Schuler, Bruno; Xu, Yong; Moll, Nikolaj; Meyer, Gerhard; Gross, Leo; Tkatchenko, Alexandre

    2016-03-17

    Reliability is one of the major concerns and challenges in designing organic/inorganic interfaces for (opto)electronic applications. Even small structural differences for molecules on substrates can result in a significant variation in the interface functionality, due to the strong correlation between geometry, stability, and electronic structure. Here, we employed state-of-the-art first-principles calculations with van der Waals interactions, in combination with atomic force microscopy experiments, to explore the interaction mechanism for three structurally related olympicene molecules adsorbed on the Cu(111) surface. The substitution of a single atom in the olympicene molecule switches the nature of adsorption from predominantly physisorptive character [olympicene on Cu(111)], to an intermediate state [olympicene-derived ketone on Cu(111)], then to chemisorptive character [olympicene radical on Cu(111)]. Despite the remarkable difference in adsorption structures (by up to 0.9 Å in adsorption height) and different nature of bonding, the olympicene, its ketone, and its radical derivatives have essentially identical binding energies and work functions upon interaction with the metal substrate. Our findings suggest that the stability and work functions of molecular adsorbates could be rendered insensitive to their adsorption structures, which could be a useful property for (opto)electronic applications. PMID:26928143

  13. Environmental implications of increased biomass energy use

    SciTech Connect

    Miles, T.R. Sr.; Miles, T.R. Jr. , Portland, OR )

    1992-03-01

    This study reviews the environmental implications of continued and increased use of biomass for energy to determine what concerns have been and need to be addressed and to establish some guidelines for developing future resources and technologies. Although renewable biomass energy is perceived as environmentally desirable compared with fossil fuels, the environmental impact of increased biomass use needs to be identified and recognized. Industries and utilities evaluating the potential to convert biomass to heat, electricity, and transportation fuels must consider whether the resource is reliable and abundant, and whether biomass production and conversion is environmentally preferred. A broad range of studies and events in the United States were reviewed to assess the inventory of forest, agricultural, and urban biomass fuels; characterize biomass fuel types, their occurrence, and their suitability; describe regulatory and environmental effects on the availability and use of biomass for energy; and identify areas for further study. The following sections address resource, environmental, and policy needs. Several specific actions are recommended for utilities, nonutility power generators, and public agencies.

  14. Linear solvation energy relationships (LSER) for adsorption of organic compounds by carbon nanotubes.

    PubMed

    Ersan, Gamze; Apul, Onur G; Karanfil, Tanju

    2016-07-01

    The objective of this paper was to create a comprehensive database for the adsorption of organic compounds by carbon nanotubes (CNTs) and to use the Linear Solvation Energy Relationship (LSER) technique for developing predictive adsorption models of organic compounds (OCs) by multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs). Adsorption data for 123 OCs by MWCNTs and 48 OCs by SWCNTs were compiled from the literature, including some experimental results obtained in our laboratory. The roles of selected OCs properties and CNT types were examined with LSER models. The results showed that the r(2) values of the LSER models displayed small variability for aromatic compounds smaller than 220 g/mol, after which a decreasing trend was observed. The data available for aliphatics was mainly for molecular weights smaller than 250 g/mol, which showed a similar trend to that of aromatics. The r(2) values for the LSER model on the adsorption of aromatic and aliphatic OCs by SWCNTs and MWCNTs were relatively similar indicating the linearity of LSER models did not depend on the CNT types. Among all LSER model descriptors, V term (molecular volume) for aromatic OCs and B term (basicity) for aliphatic OCs were the most predominant descriptors on both type of CNTs. The presence of R term (excess molar refractivity) in LSER model equations resulted in decreases for both V and P (polarizability) parameters without affecting the r(2) values. Overall, the results demonstrate that successful predictive models can be developed for the adsorption of OCs by MWCNTs and SWCNTs with LSER techniques. PMID:27064209

  15. High surface-area amidoxime-based polymer fibers co-grafted with various acid monomers yielding increased adsorption capacity for the extraction of uranium from seawater.

    PubMed

    Oyola, Yatsandra; Dai, Sheng

    2016-06-01

    Uranium is dissolved in the ocean at a uniform concentration of 3.34 ppb, which translates to approximately 4-5 billion tons of uranium. The development of adsorbents that can extract uranium from seawater has been a long term goal, but the extremely dilute uranium concentration along with the competition of other metal salts (which are at higher concentrations) has hindered the development of an economical adsorption process. Several acid monomers were co-grafted with acrylonitrile (AN) to help increase the hydrophilicity of the adsorbent to improve access to the metal adsorption sites. Grafting various acid monomers on PE fibers was found to significantly affect the uranium adsorption in simulated seawater in the following order: acrylic acid (AA) < vinyl sulfonic acid (VSA) < methacrylic acid (MAA) < itaconic acid (ITA) < vinyl phosphonic acid (VPA). Interestingly, the uranium adsorption capacity significantly increased when Mohr's salt was added with acrylic acid, most likely due to the reduction of co-polymerization of the monomers. When testing under more realistic conditions, the acid-grafted PE fiber adsorbents were exposed to natural seawater (more dilute uranium), the uranium adsorption capacity increased in the following order: MAA < AA (Mohr's salt) < VSA < ITA (Mohr's salt) < ITA < VPA, which agreed well with the simulated seawater results. Characterization of the adsorbents indicated that the increase in uranium adsorption capacity with each acid monomer was related to higher grafting of AN and therefore a higher conversion to amidoxime (AO). PMID:27145863

  16. Vibrational energy transfer near a dissociative adsorption transition state: State-to-state study of HCl collisions at Au(111)

    NASA Astrophysics Data System (ADS)

    Geweke, Jan; Shirhatti, Pranav R.; Rahinov, Igor; Bartels, Christof; Wodtke, Alec M.

    2016-08-01

    In this work we seek to examine the nature of collisional energy transfer between HCl and Au(111) for nonreactive scattering events that sample geometries near the transition state for dissociative adsorption by varying both the vibrational and translational energy of the incident HCl molecules in the range near the dissociation barrier. Specifically, we report absolute vibrational excitation probabilities for HCl(v = 0 → 1) and HCl(v = 1 → 2) scattering from clean Au(111) as a function of surface temperature and incidence translational energy. The HCl(v = 2 → 3) channel could not be observed—presumably due to the onset of dissociation. The excitation probabilities can be decomposed into adiabatic and nonadiabatic contributions. We find that both contributions strongly increase with incidence vibrational state by a factor of 24 and 9, respectively. This suggests that V-T as well as V-EHP coupling can be enhanced near the transition state for dissociative adsorption at a metal surface. We also show that previously reported HCl(v = 0 → 1) excitation probabilities [Q. Ran et al., Phys. Rev. Lett. 98, 237601 (2007)]—50 times smaller than those reported here—were influenced by erroneous assignment of spectroscopic lines used in the data analysis.

  17. Vibrational energy transfer near a dissociative adsorption transition state: State-to-state study of HCl collisions at Au(111).

    PubMed

    Geweke, Jan; Shirhatti, Pranav R; Rahinov, Igor; Bartels, Christof; Wodtke, Alec M

    2016-08-01

    In this work we seek to examine the nature of collisional energy transfer between HCl and Au(111) for nonreactive scattering events that sample geometries near the transition state for dissociative adsorption by varying both the vibrational and translational energy of the incident HCl molecules in the range near the dissociation barrier. Specifically, we report absolute vibrational excitation probabilities for HCl(v = 0 → 1) and HCl(v = 1 → 2) scattering from clean Au(111) as a function of surface temperature and incidence translational energy. The HCl(v = 2 → 3) channel could not be observed-presumably due to the onset of dissociation. The excitation probabilities can be decomposed into adiabatic and nonadiabatic contributions. We find that both contributions strongly increase with incidence vibrational state by a factor of 24 and 9, respectively. This suggests that V-T as well as V-EHP coupling can be enhanced near the transition state for dissociative adsorption at a metal surface. We also show that previously reported HCl(v = 0 → 1) excitation probabilities [Q. Ran et al., Phys. Rev. Lett. 98, 237601 (2007)]-50 times smaller than those reported here-were influenced by erroneous assignment of spectroscopic lines used in the data analysis. PMID:27497574

  18. Revisiting Bangham's law of adsorption-induced deformation: changes of surface energy and surface stress.

    PubMed

    Gor, Gennady Y; Bernstein, Noam

    2016-04-14

    When fluids are adsorbed on a solid surface they induce noticeable stresses, which cause the deformation of the solid. D. H. Bangham and co-authors performed a series of experimental measurements of adsorption-induced strains, and concluded that physisorption causes expansion, which is proportional to the lowering of the surface energy Δγ. This statement is referred to as the Bangham effect or Bangham's law. However, it is known that the quantity that controls the deformation is actually the change in surface stress Δf rather than surface energy Δγ, but this difference has not been considered in the context of adsorption-induced deformation of mesoporous materials. We use the Brunauer-Emmett-Teller (BET) theory to derive both values and show the difference between them. We find the condition when the difference between the two vanishes, and Bangham's law is applicable; it is likely that this condition is satisfied in most cases, and prediction of strain based on Δγ is a good approximation. We show that this is the case for adsorption of argon and water on Vycor glass. Finally, we show that the difference between Δγ and Δf can explain some of the experimental data that contradicts Bangham's law. PMID:27001041

  19. Changes in the size of the apparent surface area and adsorption energy of the rye roots by low pH and the presence of aluminium ions induced

    NASA Astrophysics Data System (ADS)

    Szatanik-Kloc, Alicja

    2016-07-01

    The plant reactions on Al-stress include i.a. change of the surface area of the roots, which in the physicochemistry of plants characterizes the transport of water and ions through the root. The object of this study is the specific surface area of the roots of plants which are tolerant to aluminium, such as rye. Plants of rye were grown in a nutrient solution for 14 days at pH 4.5 in the presence of Al3+ ions of concentration 10, 20, and 40 mg dm-3. The control plants were grown continuously at pH 7 or pH 4.5 without Al3+. The apparent surface area and adsorption energy of the plants roots were determined from water vapour adsorption - desorption data. The apparent surface area of roots growing in the aluminium was (with respect to control) statistically significantly lower. There were no statistically significant differences in the apparent surface area of the roots which grew in pH 7, pH 4.5 without Al3+. The average water vapour adsorption energy of the root surface, under stress conditions decreased. In the roots grown in the presence of Al+3, there was a slight decrease in high energy adsorption centres and an increase in the amount of low-energy centres.

  20. Waste-to-energy generation increases

    SciTech Connect

    Hansen, T.

    1995-06-01

    Accoding to a study by Government Advisory Associates Inc. (GAA), wse-to-energy (WTE) facilities located in the US have a generating capacity of 2,963 MW. Another 797 MW will soon be added to this capacity by facilities that are currently under construction or in the advanced planning stages. Capacity will increase by 435 MW if current conceptual sites pan out.Even though fewer WTE projects are being planned, there are more WTE facilities now open than at any time in US history. Electricity is the single energy product for almost half the WTE facilities that are now operating. Most of the facilities are owned by private companies, municipalities or counties. The main purpose of WTE facilities has been, and still is, to reduce the amount of wste that must be buried in landfills. The production of energy has simply reduced waste disposal costs. The sale of electricity involves considerably less financial risk to plant developers since the market for electricity is far more stable. It is still not yet proven that a commercial facility is economically competitive, but it is expected to be less than the cost of using natural gas.

  1. First principles total energy studies of the adsorption of disilane on Ge(001)-c(2x4)

    NASA Astrophysics Data System (ADS)

    Cocoletzi, Gregorio H.; Sanchez-Castillo, A.; Takeuchi, N.

    2004-03-01

    We perform first principles total energy calculations to investigate the energetics and the atomic structure of the adsorption of silane (SiH_4) and disilane (Si_2H_6) on the Ge(001)-c(2× 4) surface. The adsorption of Si_2H6 is a dissociative process which first yields SiH3 and then SiH2 fragments. We first study the adsorption of SiH2 considering two different models; the intra-row and the on-dimer geometries. Our results show that the on-dimer site is more stable than the intra-row geometry. This is not a surprise since in the absence of H atoms adsorption in the on-dimer site leaves no dangling bonds. In contrast, when the SiH2 fragment is considered together with two H atoms, the intra-row geometry is favored energetically as compared with the on-dimer site. Similar results have been previously obtained for the adsorption of SiH2 on Si(001). Disilane adsorption is explored according to two different geometries. In the first one, we have considered the adsorption as two SiH3 fragments, while in the second, we have considered the adsorption as two SiH2 fragments plus 2 H fragments. It is found that the later geometry is energetically more favorable.

  2. Enhanced charge efficiency and reduced energy use in capacitive deionization by increasing the discharge voltage.

    PubMed

    Kim, T; Dykstra, J E; Porada, S; van der Wal, A; Yoon, J; Biesheuvel, P M

    2015-05-15

    Capacitive deionization (CDI) is an electrochemical method for water desalination using porous carbon electrodes. A key parameter in CDI is the charge efficiency, Λ, which is the ratio of salt adsorption over charge in a CDI-cycle. Values for Λ in CDI are typically around 0.5-0.8, significantly less than the theoretical maximum of unity, due to the fact that not only counterions are adsorbed into the pores of the carbon electrodes, but at the same time coions are released. To enhance Λ, ion-exchange membranes (IEMs) can be implemented. With membranes, Λ can be close to unity because the membranes only allow passage for the counterions. Enhancing the value of Λ is advantageous as this implies a lower electrical current and (at a fixed charging voltage) a reduced energy use. We demonstrate how, without the need to include IEMs, the charge efficiency can be increased to values close to the theoretical maximum of unity, by increasing the cell voltage during discharge, with only a small loss of salt adsorption capacity per cycle. In separate constant-current CDI experiments, where after some time the effluent salt concentration reaches a stable value, this value is reached earlier with increased discharge voltage. We compare the experimental results with predictions of porous electrode theory which includes an equilibrium Donnan electrical double layer model for salt adsorption in carbon micropores. Our results highlight the potential of modified operational schemes in CDI to increase charge efficiency and reduce energy use of water desalination. PMID:25278271

  3. Atomistic simulations of crystal-melt interfaces in a model binary alloy: Interfacial free energies, adsorption coefficients, and excess entropy

    NASA Astrophysics Data System (ADS)

    Becker, C. A.; Olmsted, D. L.; Asta, M.; Hoyt, J. J.; Foiles, S. M.

    2009-02-01

    Monte Carlo and molecular-dynamics simulations are employed in a study of the equilibrium structural and thermodynamic properties of crystal-melt interfaces in a model binary alloy system described by Lennard-Jones interatomic interactions with zero size mismatch, a ratio of interaction strengths equal to 0.75, and interspecies interactions given by Lorentz-Berthelot mixing rules. This alloy system features a simple lens-type solid-liquid phase diagram at zero pressure, with nearly ideal solution thermodynamics in the solid and liquid solution phases. Equilibrium density profiles are computed for (100)-oriented crystal-melt interfaces and are used to derive the magnitudes of the relative adsorption coefficients (Γi(j)) at six temperatures along the solidus/liquidus boundary. The values for Γ1(2) , the relative adsorption of the lower melting-point species (1) with respect to the higher melting point species (2), are found to vary monotonically with temperature, with values that are positive and in the range of a few atomic percent per interface site. By contrast, values of Γ2(1) display a much more complex temperature dependence with a large peak in the magnitude of the relative adsorption more than ten times larger than those found for Γ1(2) . The capillary fluctuation method is used to compute the temperature dependence of the magnitudes and anisotropies of the crystal-melt interfacial free energy (γ) . At all temperatures we obtain the ordering γ100>γ110>γ111 for the high-symmetry (100), (110), and (111) interface orientations. The values of γ monotonically decrease with decreasing temperature (i.e., increasing concentration of the lower melting-point species). Using the calculated temperature-dependent values of γ and Γ1(2) in the Gibbs adsorption theorem, we estimate that roughly 25% of the temperature dependence of γ for the alloys can be attributed to interface adsorption, while the remaining contribution arises from the relative excess entropy

  4. Lithium inclusion in indium metal-organic frameworks showing increased surface area and hydrogen adsorption

    SciTech Connect

    Bosch, Mathieu; Zhang, Muwei; Feng, Dawei; Yuan, Shuai; Wang, Xuan; Chen, Ying-Pin; Zhou, Hong-Cai

    2014-12-01

    Investigation of counterion exchange in two anionic In-Metal-Organic Frameworks (In-MOFs) showed that partial replacement of disordered ammonium cations was achieved through the pre-synthetic addition of LiOH to the reaction mixture. This resulted in a surface area increase of over 1600% in (Li [In(1,3 − BDC){sub 2}]){sub n} and enhancement of the H{sub 2} uptake of approximately 275% at 80 000 Pa at 77 K. This method resulted in frameworks with permanent lithium content after repeated solvent exchange as confirmed by inductively coupled plasma mass spectrometry. Lithium counterion replacement appears to increase porosity after activation through replacement of bulkier, softer counterions and demonstrates tuning of pore size and properties in MOFs.

  5. Proposed Department of Energy Budget Increases Support for Renewable Energy

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2013-04-01

    In the Obama administration's proposed budget for fiscal year (FY) 2014, the Department of Energy (DOE) would get a total of 28.4 billion, up from 26.3 billion in FY 2012, an 8% increase (comparisons are to FY 2012 because final appropriations for 2013 were not available when the president released his proposed FY 2014 budget).

  6. Gamete Therapeutics: Recombinant Protein Adsorption by Sperm for Increasing Fertility via Artificial Insemination

    PubMed Central

    Alvarez-Gallardo, Horacio; Kjelland, Michael E.; Moreno, Juan F.; Welsh, Thomas H.; Randel, Ronald D.; Lammoglia, Miguel A.; Pérez-Martínez, Mario; Lara-Sagahón, Alma V.; Esperón-Sumano, A. Enrique; Romo, Salvador

    2013-01-01

    A decrease in fertility can have a negative economic impact, both locally and over a broader geographical scope, and this is especially the case with regard to the cattle industry. Therefore, much interest exists in evaluating proteins that might be able to increase the fertility of sperm. Heparin binding proteins (HBPs), specifically the fertility associated antigen (FAA) and the Type-2 tissue inhibitor of metalloproteinase (TIMP-2), act to favor the capacitation and acrosome reaction and perhaps even modulate the immune system’s response toward the sperm. The objective of this research was to determine the effect on fertility of adding recombinant FAA (rFAA) and recombinant TIMP-2 (rTIMP-2) to bovine semen before cryopreservation for use in an artificial insemination (AI) program in a tropical environment. For this experiment, 100 crossbred (Bos taurus x Bos indicus) heifers were selected based on their estrus cycle, body condition score (BCS), of 4 to 6 on a scale of 1 to 9, and adequate anatomical conformation evaluated by pelvic and genital (normal) measurements. Heifers were synchronized using estradiol benzoate (EB), Celosil® (PGF2α) (Shering-Plough) and a controlled internal drug release (CIDR) device was inserted that contained progesterone. Inseminations were performed in two groups at random, 50 animals per group. The control group was inseminated with conventional semen. The treatment group was inseminated with semen containing rFAA (25 µg/mL) and rTIMP-2 (25 µg/mL). In the control group a 16% pregnancy rate was obtained versus a 40% pregnancy rate for the HBP treatment group, resulting in a significant difference (P = 0.0037). Given the results herein, one may conclude that the HBPs can increase fertility and could be an option for cattle in tropical conditions; however, one needs to consider the environment, nutrition, and the genetic interaction affecting the final result in whatever reproductive program that is implemented. PMID:23762288

  7. Physical and chemical nature of the scaling relations between adsorption energies of atoms on metal surfaces.

    PubMed

    Calle-Vallejo, F; Martínez, J I; García-Lastra, J M; Rossmeisl, J; Koper, M T M

    2012-03-16

    Despite their importance in physics and chemistry, the origin and extent of the scaling relations between the energetics of adsorbed species on surfaces remain elusive. We demonstrate here that scalability is not exclusive to adsorbed atoms and their hydrogenated species but rather a general phenomenon between any set of adsorbates bound similarly to the surface. On the example of the near-surface alloys of Pt, we show that scalability is a result of identical variations of adsorption energies with respect to the valence configuration of both the surface components and the adsorbates. PMID:22540492

  8. Adsorption Energy Trends on UO2 and ThO2 Surfaces

    NASA Astrophysics Data System (ADS)

    Skomurski, F. N.; Shuller, L. C.; Ewing, R. C.; Becker, U.

    2006-05-01

    Uranium dioxide (UO2) comprises approximately 96 percent of spent nuclear fuel (SNF). Therefore, the interaction of UO2 surfaces with adsorbates such as water and oxygen affects the stability of SNF as a wasteform in a geologic repository. While spectroscopic studies are used to observe surface-adsorbate interactions, questions remain regarding the mechanisms driving the initial reactions between UO2 surfaces and adsorbates. Through the use of quantum mechanical techniques, adsorption and dissociation interactions between different UO2 surfaces and oxygen and water are explored as a function of surface structure. Comparisons are also made with thorium dioxide (ThO2), a nuclear material that is isostructural with UO2, in order to test surface-adsorbate interactions as a function of insulating versus semi-conducting material properties, respectively. In this study, the density functional theory-based quantum mechanical code, CASTEP (CAmbridge Serial Total Energy Package), is used to calculate adsorption energies and changes in electronic structure between clean and adsorbate-covered UO2 and ThO2 surfaces. Four different adsorption cases are tested on the UO2 (111) and (110) surfaces: (i) one-half mono-layer (ML) of molecular water, (ii) one-half ML of dissociated water, (iii) one-half ML of dissociated oxygen, and (iv) a combined molecular water and dissociated oxygen case. The same cases are also tested on the ThO2 (111) surface. Calculations involving the oxidation of bulk UO2 are also performed for comparison with surface processes.

  9. Metal-phthalocyanine ordered layers on Au(110): Metal-dependent adsorption energy

    SciTech Connect

    Massimi, Lorenzo Angelucci, Marco; Gargiani, Pierluigi; Betti, Maria Grazia; Montoro, Silvia; Mariani, Carlo

    2014-06-28

    Iron-phthalocyanine and cobalt-phthalocyanine chains, assembled along the Au(110)-(1×2) reconstructed channels, present a strong interaction with the Au metallic states, via the central metal ion. X-ray photoemission spectroscopy from the metal-2p core-levels and valence band high-resolution ultraviolet photoelectron spectroscopy bring to light signatures of the interaction of the metal-phthalocyanine single-layer with gold. The charge transfer from Au to the molecule causes the emerging of a metal-2p core level component at lower binding energy with respect to that measured in the molecular thin films, while the core-levels associated to the organic macrocycle (C and N 1s) are less influenced by the adsorption, and the macrocycles stabilize the interaction, inducing a strong interface dipole. Temperature Programmed Desorption experiments and photoemission as a function of temperature allow to estimate the adsorption energy for the thin-films, mainly due to the molecule-molecule van der Waals interaction, while the FePc and CoPc single-layers remain adsorbed on the Au surface up to at least 820 K.

  10. Improvement of pesticide adsorption capacity of cellulose fibre by high-energy irradiation-initiated grafting of glycidyl methacrylate

    NASA Astrophysics Data System (ADS)

    Takács, Erzsébet; Wojnárovits, László; Koczog Horváth, Éva; Fekete, Tamás; Borsa, Judit

    2012-09-01

    Cellulose as a renewable raw material was used for preparation of adsorbent of organic impurities in wastewater treatment. Hydrophobic surface of cellulose substrate was developed by grafting glycidyl methacrylate in simultaneous grafting using gamma irradiation initiation. Water uptake of cellulose significantly decreased while adsorption of phenol and a pesticide molecule (2,4-dichlorophenoxyacetic acid: 2,4-D) increased upon grafting. Adsorption equilibrium data fitted the Freundlich isotherm for both solutes.

  11. Optimization of reaction conditions towards multiple types of framework isomers and periodic-increased porosity: luminescence properties and selective CO2 adsorption over N2.

    PubMed

    Wu, Xiao-Liu; Luo, Feng; Sun, Gong-Ming; Zheng, An-Min; Zhang, Jian; Luo, Ming-Biao; Xu, Wen-Yuan; Zhu, Yan; Zhang, Xiao-Min; Huang, Shu-Yun

    2013-10-21

    Three new metal-organic frameworks (MOFs) were prepared by solvo(hydro)thermolysis and further characterized as framework isomers. The structural transformation from non-porous to porous MOFs and the purity of these products can be modulated by controlling the reaction temperature. The periodic-increased porosity observed was further confirmed by CO2 adsorption isotherms. Owing to the presence of acylamide groups in the pore walls and the flexible nature of the skeleton of these MOFs, highly selective CO2 adsorption over N2 was observed, as well as structure-dependent periodic varieties in luminescence properties. PMID:24038959

  12. Adsorption of Organic Compounds to Diesel Soot: Frontal Analysis and Polyparameter Linear Free-Energy Relationship.

    PubMed

    Lu, Zhijiang; MacFarlane, John K; Gschwend, Philip M

    2016-01-01

    Black carbons (BCs) dominate the sorption of many hydrophobic organic compounds (HOCs) in soils and sediments, thereby reducing the HOCs' mobilities and bioavailabilities. However, we do not have data for diverse HOCs' sorption to BC because it is time-consuming and labor-intensive to obtain isotherms on soot and other BCs. In this study, we developed a frontal analysis chromatographic method to investigate the adsorption of 21 organic compounds with diverse functional groups to NIST diesel soot. This method was precise and time-efficient, typically taking only a few hours to obtain an isotherm. Based on 102 soot-carbon normalized sorption coefficients (KsootC) acquired at different sorbate concentrations, a sorbate-activity-dependent polyparameter linear free-energy relationship was established: logKsootC = (3.74 ± 0.11)V + ((-0.35 ± 0.02)log ai)E + (-0.62 ± 0.10)A + (-3.35 ± 0.11)B + (-1.45 ± 0.09); (N = 102, R(2) = 0.96, SE = 0.18), where V, E, A, and B are the sorbate's McGowan's characteristic volume, excess molar refraction, and hydrogen acidity and basicity, respectively; and ai is the sorbate's aqueous activity reflecting the system's approach to saturation. The difference in dispersive interactions with the soot versus with the water was the dominant factor encouraging adsorption, and H-bonding interactions discouraged this process. Using this relationship, soot-water and sediment-water or soil-water adsorption coefficients of HOCs of interest (PAHs and PCBs) were estimated and compared with the results reported in the literature. PMID:26587648

  13. Towards increased policy relevance in energy modeling

    SciTech Connect

    Worrell, Ernst; Ramesohl, Stephan; Boyd, Gale

    2003-07-29

    Historically, most energy models were reasonably equipped to assess the impact of a subsidy or change in taxation, but are often insufficient to assess the impact of more innovative policy instruments. We evaluate the models used to assess future energy use, focusing on industrial energy use. We explore approaches to engineering-economic analysis that could help improve the realism and policy relevance of engineering-economic modeling frameworks. We also explore solutions to strengthen the policy usefulness of engineering-economic analysis that can be built from a framework of multi-disciplinary cooperation. We focus on the so-called ''engineering-economic'' (or ''bottom-up'') models, as they include the amount of detail that is commonly needed to model policy scenarios. We identify research priorities for the modeling framework, technology representation in models, policy evaluation and modeling of decision-making behavior.

  14. Protein Adsorption in Three Dimensions

    PubMed Central

    Vogler, Erwin A.

    2011-01-01

    initially-adsorbed protein. Interphase protein concentration CI increases as VI decreases, resulting in slow reduction in interfacial energetics. Steady-state is governed by a net partition coefficient P=(/CBCI). In the process of occupying space within the interphase, adsorbing protein molecules must displace an equivalent volume of interphase water. Interphase water is itself associated with surface-bound water through a network of transient hydrogen bonds. Displacement of interphase water thus requires an amount of energy that depends on the adsorbent surface chemistry/energy. This “adsorption-dehydration” step is the significant free-energy cost of adsorption that controls the maximum amount of protein that can be adsorbed at steady state to a unit adsorbent-surface area (the adsorbent capacity). As adsorbent hydrophilicity increases, protein adsorption monotonically decreases because the energetic cost of surface dehydration increases, ultimately leading to no protein adsorption near an adsorbent water wettability (surface energy) characterized by a water contact angle θ → 65°. Consequently, protein does not adsorb (accumulate at interphase concentrations greater than bulk solution) to more hydrophilic adsorbents exhibiting θ < 65° . For adsorbents bearing strong Lewis acid/base chemistry such as ion-exchange resins, protein/surface interactions can be highly favorable, causing protein to adsorb in multilayers in a relatively thick interphase. A straightforward, three-component free energy relationship captures salient features of protein adsorption to all surfaces predicting that the overall free energy of protein adsorption ΔGadso is a relatively small multiple of thermal energy for any surface chemistry (except perhaps for bioengineered surfaces bearing specific ligands for adsorbing protein) because a surface chemistry that interacts chemically with proteins must also interact with water through hydrogen bonding. In this way, water moderates protein

  15. Software Cuts Homebuilding Costs, Increases Energy Efficiency

    NASA Technical Reports Server (NTRS)

    2015-01-01

    To sort out the best combinations of technologies for a crewed mission to Mars, NASA Headquarters awarded grants to MIT's Department of Aeronautics and Astronautics to develop an algorithm-based software tool that highlights the most reliable and cost-effective options. Utilizing the software, Professor Edward Crawley founded Cambridge, Massachussetts-based Ekotrope, which helps homebuilders choose cost- and energy-efficient floor plans and materials.

  16. On sulfur core level binding energies in thiol self-assembly and alternative adsorption sites: An experimental and theoretical study.

    PubMed

    Jia, Juanjuan; Kara, Abdelkader; Pasquali, Luca; Bendounan, Azzedine; Sirotti, Fausto; Esaulov, Vladimir A

    2015-09-14

    Characteristic core level binding energies (CLBEs) are regularly used to infer the modes of molecular adsorption: orientation, organization, and dissociation processes. Here, we focus on a largely debated situation regarding CLBEs in the case of chalcogen atom bearing molecules. For a thiol, this concerns the case when the CLBE of a thiolate sulfur at an adsorption site can be interpreted alternatively as due to atomic adsorption of a S atom, resulting from dissociation. Results of an investigation of the characteristics of thiol self-assembled monolayers (SAMs) obtained by vacuum evaporative adsorption are presented along with core level binding energy calculations. Thiol ended SAMs of 1,4-benzenedimethanethiol (BDMT) obtained by evaporation on Au display an unconventional CLBE structure at about 161.25 eV, which is close to a known CLBE of a S atom on Au. Adsorption and CLBE calculations for sulfur atoms and BDMT molecules are reported and allow delineating trends as a function of chemisorption on hollow, bridge, and atop sites and including the presence of adatoms. These calculations suggest that the 161.25 eV peak is due to an alternative adsorption site, which could be associated to an atop configuration. Therefore, this may be an alternative interpretation, different from the one involving the adsorption of atomic sulfur resulting from the dissociation process of the S-C bond. Calculated differences in S(2p) CLBEs for free BDMT molecules, SH group sulfur on top of the SAM, and disulfide are also reported to clarify possible errors in assignments. PMID:26374051

  17. On sulfur core level binding energies in thiol self-assembly and alternative adsorption sites: An experimental and theoretical study

    SciTech Connect

    Jia, Juanjuan; Kara, Abdelkader E-mail: vladimir.esaulov@u-psud.fr; Pasquali, Luca; Bendounan, Azzedine; Sirotti, Fausto; Esaulov, Vladimir A. E-mail: vladimir.esaulov@u-psud.fr

    2015-09-14

    Characteristic core level binding energies (CLBEs) are regularly used to infer the modes of molecular adsorption: orientation, organization, and dissociation processes. Here, we focus on a largely debated situation regarding CLBEs in the case of chalcogen atom bearing molecules. For a thiol, this concerns the case when the CLBE of a thiolate sulfur at an adsorption site can be interpreted alternatively as due to atomic adsorption of a S atom, resulting from dissociation. Results of an investigation of the characteristics of thiol self-assembled monolayers (SAMs) obtained by vacuum evaporative adsorption are presented along with core level binding energy calculations. Thiol ended SAMs of 1,4-benzenedimethanethiol (BDMT) obtained by evaporation on Au display an unconventional CLBE structure at about 161.25 eV, which is close to a known CLBE of a S atom on Au. Adsorption and CLBE calculations for sulfur atoms and BDMT molecules are reported and allow delineating trends as a function of chemisorption on hollow, bridge, and atop sites and including the presence of adatoms. These calculations suggest that the 161.25 eV peak is due to an alternative adsorption site, which could be associated to an atop configuration. Therefore, this may be an alternative interpretation, different from the one involving the adsorption of atomic sulfur resulting from the dissociation process of the S–C bond. Calculated differences in S(2p) CLBEs for free BDMT molecules, SH group sulfur on top of the SAM, and disulfide are also reported to clarify possible errors in assignments.

  18. On sulfur core level binding energies in thiol self-assembly and alternative adsorption sites: An experimental and theoretical study

    NASA Astrophysics Data System (ADS)

    Jia, Juanjuan; Kara, Abdelkader; Pasquali, Luca; Bendounan, Azzedine; Sirotti, Fausto; Esaulov, Vladimir A.

    2015-09-01

    Characteristic core level binding energies (CLBEs) are regularly used to infer the modes of molecular adsorption: orientation, organization, and dissociation processes. Here, we focus on a largely debated situation regarding CLBEs in the case of chalcogen atom bearing molecules. For a thiol, this concerns the case when the CLBE of a thiolate sulfur at an adsorption site can be interpreted alternatively as due to atomic adsorption of a S atom, resulting from dissociation. Results of an investigation of the characteristics of thiol self-assembled monolayers (SAMs) obtained by vacuum evaporative adsorption are presented along with core level binding energy calculations. Thiol ended SAMs of 1,4-benzenedimethanethiol (BDMT) obtained by evaporation on Au display an unconventional CLBE structure at about 161.25 eV, which is close to a known CLBE of a S atom on Au. Adsorption and CLBE calculations for sulfur atoms and BDMT molecules are reported and allow delineating trends as a function of chemisorption on hollow, bridge, and atop sites and including the presence of adatoms. These calculations suggest that the 161.25 eV peak is due to an alternative adsorption site, which could be associated to an atop configuration. Therefore, this may be an alternative interpretation, different from the one involving the adsorption of atomic sulfur resulting from the dissociation process of the S-C bond. Calculated differences in S(2p) CLBEs for free BDMT molecules, SH group sulfur on top of the SAM, and disulfide are also reported to clarify possible errors in assignments.

  19. Complementing the adsorption energies of CO2, H2S and NO2 to h-BN sheets by doping with carbon

    NASA Astrophysics Data System (ADS)

    Sagynbaeva, Myskal; Hussain, Tanveer; Panigrahi, Puspamitra; Johansson, Borje; Ahuja, Rajeev

    2015-03-01

    We predict the adsorption proficiency of hexagonal boron nitride (h-BN) sheets to toxic gas molecules like CO2, H2S and NO2 on the basis of first-principles density functional theory calculations. The computed energies predict the pristine h-BN sheet to have very little affinity towards the mentioned gas molecules. However, while doping C at the N site of the h-BN sheet brings a significant enhancement to the estimated adsorption energies, doping C at B site of the sheet is found to be energetically not so favorable. To have a higher coverage effect, the concentration of C doping on the h-BN sheet is further increased which resulted in upsurging the adsorption energies for the mentioned gas molecules. Among the three, CO2, H2S are found to be physisorbed to the C-doped h-BN sheets, where as the C-doped sheets are found to have strong affinity towards NO2 gas molecules.

  20. Facile synthesis of ultrahigh-surface-area hollow carbon nanospheres for enhanced adsorption and energy storage

    NASA Astrophysics Data System (ADS)

    Xu, Fei; Tang, Zhiwei; Huang, Siqi; Chen, Luyi; Liang, Yeru; Mai, Weicong; Zhong, Hui; Fu, Ruowen; Wu, Dingcai

    2015-06-01

    Exceptionally large surface area and well-defined nanostructure are both critical in the field of nanoporous carbons for challenging energy and environmental issues. The pursuit of ultrahigh surface area while maintaining definite nanostructure remains a formidable challenge because extensive creation of pores will undoubtedly give rise to the damage of nanostructures, especially below 100 nm. Here we report that high surface area of up to 3,022 m2 g-1 can be achieved for hollow carbon nanospheres with an outer diameter of 69 nm by a simple carbonization procedure with carefully selected carbon precursors and carbonization conditions. The tailor-made pore structure of hollow carbon nanospheres enables target-oriented applications, as exemplified by their enhanced adsorption capability towards organic vapours, and electrochemical performances as electrodes for supercapacitors and sulphur host materials for lithium-sulphur batteries. The facile approach may open the doors for preparation of highly porous carbons with desired nanostructure for numerous applications.

  1. Calculation of adsorption free energy for solute-surface interactions using biased replica-exchange molecular dynamics

    PubMed Central

    Wang, Feng; Stuart, Steven J.; Latour, Robert A.

    2009-01-01

    The adsorption behavior of a biomolecule, such as a peptide or protein, to a functionalized surface is of fundamental importance for a broad range of applications in biotechnology. The adsorption free energy for these types of interactions can be determined from a molecular dynamics simulation using the partitioning between adsorbed and nonadsorbed states, provided that sufficient sampling of both states is obtained. However, if interactions between the solute and the surface are strong, the solute will tend to be trapped near the surface during the simulation, thus preventing the adsorption free energy from being calculated by this method. This situation occurs even when using an advanced sampling algorithm such as replica-exchange molecular dynamics (REMD). In this paper, the authors demonstrate the fundamental basis of this problem using a model system consisting of one sodium ion (Na+) as the solute positioned over a surface functionalized with one negatively charged group (COO−) in explicit water. With this simple system, the authors show that sufficient sampling in the coordinate normal to the surface cannot be obtained by conventional REMD alone. The authors then present a method to overcome this problem through the use of an adaptive windowed-umbrella sampling technique to develop a biased-energy function that is combined with REMD. This approach provides an effective method for the calculation of adsorption free energy for solute-surface interactions. PMID:19768127

  2. Effective coordination as a predictor of adsorption energies: A model study of NO on Rh(100) and Rh/MgO(100) surfaces

    SciTech Connect

    Pushpa, Raghani; Gironcoli, Stefano de; Narasimhan, Shobhana

    2009-04-15

    We have studied the adsorption of NO, and the coadsorption of N and O, on four physical and hypothetical systems: unstrained and strained Rh(100) surfaces and monolayers of Rh atoms on strained and unstrained MgO(100) surfaces. We find that as we go from Rh(100) to Rh/Mg0(100), via the other two hypothetical systems, the effective coordination progressively decreases, the d band narrows and its center shifts closer to the Fermi level, and the strength of adsorption and coadsorption increases. Both the strain and the presence of the oxide substrate contribute significantly to this. However, charge transfer is found to play a negligible role due to a canceling out between donation and back-donation processes. Our results suggest that lowering the effective coordination of Rh catalysts by strain, roughening, or the use of inert substrates might lower activation energies for the dissociation of NO.

  3. Potential of mean force calculation of the free energy of adsorption of Type I winter flounder antifreeze protein on ice

    NASA Astrophysics Data System (ADS)

    Battle, Keith; Alan Salter, E.; Wesley Edmunds, R.; Wierzbicki, Andrzej

    2010-04-01

    Antifreeze proteins (AFPs) are a unique class of proteins that inhibit ice growth without changing the melting point of ice. In this work, we study the detailed molecular mechanism of interactions between the hydrophobic side of the winter flounder (WF) AFP and two mutants, AAAA and SSSS, in which threonine residues are substituted by serines and alanines, respectively. Umbrella sampling molecular dynamics simulations of the separation of the proteins from the (2 0 1) surface in an explicit water box is carried out to calculate the potential of mean force free energies of adsorption using AMBER10i. We estimate wild-type WF's free energy of adsorption to ice to be about -12.0 kcal/mol. Gas-phase pseudopotential plane-wave calculations of methane adsorption onto select surfaces of ice are also carried out under periodic boundary conditions to address the possible enthalpic role of WF's methyl groups in binding. The contributions of hydrophobic residues to the free energy of adsorption are discussed.

  4. Modification of carbon-coated TiO2 by iron to increase adsorptivity and photoactivity for phenol.

    PubMed

    Tryba, B; Toyoda, M; Morawski, A W; Inagaki, M

    2005-07-01

    Carbon-coated TiO(2) modified by iron, were prepared from TiO(2) of anatase structure and PET modified by FeC(2)O(4). Catalysts were prepared by mixing powders of TiO(2) and modified PET and heating at different temperatures, from 400 to 800 degrees C under flow of Ar gas. High adsorption of phenol was observed on the catalyst heated at 400 degrees C, confirmed by FT-IR analysis. On this catalyst, fast rate of phenol decomposition was achieved by addition of small amount of H(2)O(2) to the reaction mixture. Phenol decomposition proceeded mainly through the direct oxidation of phenol species adsorbed on the catalyst surface due to the photo-Fenton reaction. Iron-modified carbon-coated TiO(2) catalysts heated at 500-800 degrees C showed almost no phenol adsorption or oxidation. PMID:15950040

  5. Surface free energies and elemental surface compositions of human enamel after application of commercially available mouthrinses and adsorption of salivary constituents.

    PubMed

    Perdok, J F; Van Der Mei, H C; Busscher, H J; Genet, M J; Rouxhet, P G

    1990-01-01

    The adsorption of active agents from six commercially available mouthrinses to ground and polished enamel, with and without adsorbed salivary constituents, was monitored by contact angle measurements and X-ray Photoelectron Spectroscopy (XPS). Human enamel samples were treated with mouthrinses containing chlorhexidine (Peridex), stannous fluoride/amine fluoride (Meridol), thymol/benzoic acid (Listerine), sanguinarine (Veadent), sodium fluoride (Prodent), or cetylpyridinium chloride (Merocet). XPS indicated a sizeable adsorption of both active and non-active components for all products. After treatment, all enamel surface free energies increased except for the stannous fluoride/amine fluoride containing mouthrinse. It is suggested that non-active components in the products cause an increase in surface free energy. Despite this thermodynamically unfavorable increase in surface free energy, all rinses have plaque reducing effects, indicating that this unfavorable surface characteristic is overruled by the antibacterial properties of the components. Replacement of non-active components by less adsorbing surfactants could increase the efficiency of the products tested. PMID:2090159

  6. Adsorption calorimetry during metal vapor deposition on single crystal surfaces: Increased flux, reduced optical radiation, and real-time flux and reflectivity measurements

    SciTech Connect

    Sellers, Jason R. V.; James, Trevor E.; Hemmingson, Stephanie L.; Farmer, Jason A.; Campbell, Charles T.

    2013-12-15

    Thin films of metals and other materials are often grown by physical vapor deposition. To understand such processes, it is desirable to measure the adsorption energy of the deposited species as the film grows, especially when grown on single crystal substrates where the structure of the adsorbed species, evolving interface, and thin film are more homogeneous and well-defined in structure. Our group previously described in this journal an adsorption calorimeter capable of such measurements on single-crystal surfaces under the clean conditions of ultrahigh vacuum [J. T. Stuckless, N. A. Frei, and C. T. Campbell, Rev. Sci. Instrum. 69, 2427 (1998)]. Here we describe several improvements to that original design that allow for heat measurements with ∼18-fold smaller standard deviation, greater absolute accuracy in energy calibration, and, most importantly, measurements of the adsorption of lower vapor-pressure materials which would have previously been impossible. These improvements are accomplished by: (1) using an electron beam evaporator instead of a Knudsen cell to generate the metal vapor at the source of the pulsed atomic beam, (2) changing the atomic beam design to decrease the relative amount of optical radiation that accompanies evaporation, (3) adding an off-axis quartz crystal microbalance for real-time measurement of the flux of the atomic beam during calorimetry experiments, and (4) adding capabilities for in situ relative diffuse optical reflectivity determinations (necessary for heat signal calibration). These improvements are not limited to adsorption calorimetry during metal deposition, but also could be applied to better study film growth of other elements and even molecular adsorbates.

  7. Adsorption energies of poly(ethylene oxide)-based surfactants and nanoparticles on an air-water surface.

    PubMed

    Zell, Zachary A; Isa, Lucio; Ilg, Patrick; Leal, L Gary; Squires, Todd M

    2014-01-14

    The self-assembly of polymer-based surfactants and nanoparticles on fluid-fluid interfaces is central to many applications, including dispersion stabilization, creation of novel 2D materials, and surface patterning. Very often these processes involve compressing interfacial monolayers of particles or polymers to obtain a desired material microstructure. At high surface pressures, however, even highly interfacially active objects can desorb from the interface. Methods of directly measuring the energy which keeps the polymer or particles bound to the interface (adsorption/desorption energies) are therefore of high interest for these processes. Moreover, though a geometric description linking adsorption energy and wetting properties through the definition of a contact angle can be established for rigid nano- or microparticles, such a description breaks down for deformable or aggregating objects. Here, we demonstrate a technique to quantify desorption energies directly, by comparing surface pressure-density compression measurements using a Wilhelmy plate and a custom-microfabricated deflection tensiometer. We focus on poly(ethylene oxide)-based polymers and nanoparticles. For PEO-based homo- and copolymers, the adsorption energy of PEO chains scales linearly with molecular weight and can be tuned by changing the subphase composition. Moreover, the desorption surface pressure of PEO-stabilized nanoparticles corresponds to the saturation surface pressure for spontaneously adsorbed monolayers, yielding trapping energies of ∼10(3) k(B)T. PMID:24328531

  8. 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.

  9. Effect of Increased Natural Gas Exports on Domestic Energy Markets

    EIA Publications

    2012-01-01

    This report responds to an August 2011 request from the Department of Energy's Office of Fossil Energy (DOE\\/FE) for an analysis of "the impact of increased domestic natural gas demand, as exports." Appendix A provides a copy of the DOE\\/FE request letter. Specifically, DOE\\/FE asked the U.S. Energy Information Administration (EIA) to assess how specified scenarios of increased natural gas exports could affect domestic energy markets, focusing on consumption, production, and prices.

  10. 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.

  11. Prediction of binding free energy for adsorption of antimicrobial peptide lactoferricin B on a POPC membrane

    NASA Astrophysics Data System (ADS)

    Vivcharuk, Victor; Tomberli, Bruno; Tolokh, Igor S.; Gray, C. G.

    2008-03-01

    Molecular dynamics (MD) simulations are used to study the interaction of a zwitterionic palmitoyl-oleoyl-phosphatidylcholine (POPC) bilayer with the cationic antimicrobial peptide bovine lactoferricin (LFCinB) in a 100 mM NaCl solution at 310 K. The interaction of LFCinB with POPC is used as a model system for studying the details of membrane-peptide interactions, with the peptide selected because of its antimicrobial nature. Seventy-two 3 ns MD simulations, with six orientations of LFCinB at 12 different distances from a POPC membrane, are carried out to determine the potential of mean force (PMF) or free energy profile for the peptide as a function of the distance between LFCinB and the membrane surface. To calculate the PMF for this relatively large system a new variant of constrained MD and thermodynamic integration is developed. A simplified method for relating the PMF to the LFCinB-membrane binding free energy is described and used to predict a free energy of adsorption (or binding) of -1.05±0.39kcal/mol , and corresponding maximum binding force of about 20 pN, for LFCinB-POPC. The contributions of the ions-LFCinB and the water-LFCinB interactions to the PMF are discussed. The method developed will be a useful starting point for future work simulating peptides interacting with charged membranes and interactions involved in the penetration of membranes, features necessary to understand in order to rationally design peptides as potential alternatives to traditional antibiotics.

  12. Fostering Sustained Energy Behavior Change and Increasing Energy Literacy in a Student Housing Energy Challenge

    ERIC Educational Resources Information Center

    Brewer, Robert Stephen

    2013-01-01

    We designed the Kukui Cup challenge to foster energy conservation and increase energy literacy. Based on a review of the literature, the challenge combined a variety of elements into an overall game experience, including: real-time energy feedback, goals, commitments, competition, and prizes. We designed a software system called Makahiki to…

  13. Facile synthesis of ultrahigh-surface-area hollow carbon nanospheres for enhanced adsorption and energy storage

    PubMed Central

    Xu, Fei; Tang, Zhiwei; Huang, Siqi; Chen, Luyi; Liang, Yeru; Mai, Weicong; Zhong, Hui; Fu, Ruowen; Wu, Dingcai

    2015-01-01

    Exceptionally large surface area and well-defined nanostructure are both critical in the field of nanoporous carbons for challenging energy and environmental issues. The pursuit of ultrahigh surface area while maintaining definite nanostructure remains a formidable challenge because extensive creation of pores will undoubtedly give rise to the damage of nanostructures, especially below 100 nm. Here we report that high surface area of up to 3,022 m2 g−1 can be achieved for hollow carbon nanospheres with an outer diameter of 69 nm by a simple carbonization procedure with carefully selected carbon precursors and carbonization conditions. The tailor-made pore structure of hollow carbon nanospheres enables target-oriented applications, as exemplified by their enhanced adsorption capability towards organic vapours, and electrochemical performances as electrodes for supercapacitors and sulphur host materials for lithium–sulphur batteries. The facile approach may open the doors for preparation of highly porous carbons with desired nanostructure for numerous applications. PMID:26072734

  14. Hydrogen adsorption on functionalized nanoporous activated carbons.

    PubMed

    Zhao, X B; Xiao, B; Fletcher, A J; Thomas, K M

    2005-05-12

    There is considerable interest in hydrogen adsorption on carbon nanotubes and porous carbons as a method of storage for transport and related energy applications. This investigation has involved a systematic investigation of the role of functional groups and porous structure characteristics in determining the hydrogen adsorption characteristics of porous carbons. Suites of carbons were prepared with a wide range of nitrogen and oxygen contents and types of functional groups to investigate their effect on hydrogen adsorption. The porous structures of the carbons were characterized by nitrogen (77 K) and carbon dioxide (273 K) adsorption methods. Hydrogen adsorption isotherms were studied at 77 K and pressure up to 100 kPa. All the isotherms were Type I in the IUPAC classification scheme. Hydrogen isobars indicated that the adsorption of hydrogen is very temperature dependent with little or no hydrogen adsorption above 195 K. The isosteric enthalpies of adsorption at zero surface coverage were obtained using a virial equation, while the values at various surface coverages were obtained from the van't Hoff isochore. The values were in the range 3.9-5.2 kJ mol(-1) for the carbons studied. The thermodynamics of the adsorption process are discussed in relation to temperature limitations for hydrogen storage applications. The maximum amounts of hydrogen adsorbed correlated with the micropore volume obtained from extrapolation of the Dubinin-Radushkevich equation for carbon dioxide adsorption. Functional groups have a small detrimental effect on hydrogen adsorption, and this is related to decreased adsorbate-adsorbent and increased adsorbate-adsorbate interactions. PMID:16852056

  15. Methanol adsorption on the clean CeO₂(111) surface: A density functional theory study

    SciTech Connect

    Mei, Donghai; Deskins, N. Aaron; Dupuis, Michel; Ge, Qingfeng

    2007-07-19

    Molecular and dissociative adsorption of methanol at various sites on the stoichiometric CeO₂(111) surface have been studied using density functional theory periodic calculations. At 0.25 monolayer (ML) coverage, the dissociative adsorption with an adsorption energy of 0.55 eV is slightly favored. The most stable state is the dissociative adsorption of methanol via C-H bond breaking, forming a coadsorbed hydroxymethyl group and hydrogen adatom on two separate O₃C surface sites. The strongest molecular adsorption occurs through an O-Ce₇subC connection with an adsorption energy of 0.48 eV. At methanol coverage of 0.5 ML, the dissociative adsorption and the molecular adsorption became competitive. The adsorption energy per methanol molecule for both adsorption modes falls into a narrow range of 0.46-0.55 eV. As methanol coverage increases beyond 0.5 ML, the molecular adsorption becomes more energetically favorable than the dissociative adsorption because of the attractive hydrogen bonding between coadsorbed methanol molecules. At full monolayer, the adsorption energy of molecular adsorption is 0.40 eV per molecule while the adsorption energy for total dissociative adsorption of methanol is only 0.17 eV. The results at different methanol coverages indicate that methanol can adsorb on a defect-free CeO₂(111) surface, which are also consistent with experimental observations. This research was performed using the Molecular Science Computing Facility in the William R. Wiley Environmental Molecular Sciences Laboratory, which is a U.S. Department of Energy national scientific user facility located at Pacific Northwest National Laboratory (PNNL) in Richland, Washington. Computing time was made available under a Computational Grand Challenge “Computational Catalysis”. This work also financially supported by the Laboratory Directed Research and Development project of PNNL.

  16. Fostering sustained energy behavior change and increasing energy literacy in a student housing energy challenge

    NASA Astrophysics Data System (ADS)

    Brewer, Robert Stephen

    We designed the Kukui Cup challenge to foster energy conservation and increase energy literacy. Based on a review of the literature, the challenge combined a variety of elements into an overall game experience, including: real-time energy feedback, goals, commitments, competition, and prizes. We designed a software system called Makahiki to provide the online portion of the Kukui Cup challenge. Energy use was monitored by smart meters installed on each floor of the Hale Aloha residence halls on the University of Hawai'i at Manoa campus. In October 2011, we ran the UH Kukui Cup challenge for the over 1000 residents of the Hale Aloha towers. To evaluate the Kukui Cup challenge, I conducted three experiments: challenge participation, energy literacy, and energy use. Many residents participated in the challenge, as measured by points earned and actions completed through the challenge website. I measured the energy literacy of a random sample of Hale Aloha residents using an online energy literacy questionnaire administered before and after the challenge. I found that challenge participants' energy knowledge increased significantly compared to non-challenge participants. Positive self-reported energy behaviors increased after the challenge for both challenge participants and non-participants, leading to the possibility of passive participation by the non-challenge participants. I found that energy use varied substantially between and within lounges over time. Variations in energy use over time complicated the selection of a baseline of energy use to compare the levels during and after the challenge. The best team reduced its energy use during the challenge by 16%. However, team energy conservation did not appear to correlate to participation in the challenge, and there was no evidence of sustained energy conservation after the challenge. The problems inherent in assessing energy conservation using a baseline call into question this common practice. My research has

  17. Can holographic dark energy increase the mass of the wormhole?

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Surajit; Momeni, Davood; Altaibayeva, Aziza; Myrzakulov, Ratbay

    2015-03-01

    Motivated by the quantum essence of wormholes, in this work, we have studied accretion of dark energy (DE) onto Morris-Thorne wormhole with three different forms, namely, holographic dark energy, holographic Ricci dark energy and modified holographic Ricci dark energy. Considering the scale factor in power-law form we have observed that as the holographic dark energy accretes onto wormhole, the mass of the wormhole is decreasing. In the next phase we considered three parameterization schemes that are able to get hold of quintessence as well as phantom phases. Without any choice of scale factor we reconstructed Hubble parameter from conservation equation and dark energy densities and subsequently got the mass of the wormhole separately for accretion of the three dark energy candidates. It was observed that if these dark energies accrete onto the wormhole, then for quintessence stage, wormhole mass decreases up to a certain finite value and then again increases to aggressively during phantom phase of the universe.

  18. Characterization of biochars derived from agriculture wastes and their adsorptive removal of atrazine from aqueous solution: A comparative study.

    PubMed

    Liu, Na; Charrua, Alberto Bento; Weng, Chih-Huang; Yuan, Xiaoling; Ding, Feng

    2015-12-01

    The physicochemical properties of biochars produced from soybeans (SBB), corn stalks (CSB), rice stalks (RSB), poultry manure (PMB), cattle manure (CMB), and pig manure (PgMB) and their adsorption characteristics of atrazine were investigated. The adsorption capacity increased with the increase of temperature and initial atrazine concentration. More atrazine was removed from basic solutions than acidic solutions, due to the effects of adsorption and hydrolysis. The Freundlich isotherm adsorption parameters indicated that the adsorption capacity decreased in the order SBB>RSB>CMB>CSB>PMB>PgMB, which is associated to the pore volume of biochars. The total pore volume and biochar pH were concluded to play important roles in determining the adsorption capacity, and they may have contributed to physical adsorption mechanisms dominating the overall adsorption process (the low activation energy for all of the biochars). Modified Freundlich and intraparticle diffusion models were used to describe the kinetics of the adsorption process. PMID:26364228

  19. 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.

  20. New Operational Modes to Increase Energy Efficiency in Capacitive Deionization Systems.

    PubMed

    García-Quismondo, Enrique; Santos, Cleis; Soria, Jorge; Palma, Jesús; Anderson, Marc A

    2016-06-01

    In order for capacitive deionization (CDI) as a water treatment technology to achieve commercial success, substantial improvements in the operational aspects of the system should be improved in order to efficiently recover the energy stored during the deionization step. In the present work, to increase the energy efficiency of the adsorption-desorption processes, we propose a new operational procedure that utilizes a concentrated brine stream as a washing solution during regeneration. Using this approach, we demonstrate that by replacing the electrolyte during regeneration for a solution with higher conductivity, it is possible to substantially increase round-trip energy efficiency. This procedure was experimentally verified in a flow cell reactor using a pair of carbon electrodes (10(2) cm geometric area) and NaCl solutions having concentrations between 50 and 350 mmol·L(-1). According to experimental data, this new operational mode allows for a better utilization of the three-dimensional structure of the porous material. This increases the energetic efficiency of the global CDI process to above 80% when deionization/regeneration currents ratio are optimized for brackish water treatment. PMID:27167689

  1. Solar collector apparatus having increased energy rejection during stagnation

    DOEpatents

    Moore, S.W.

    1981-01-16

    An active solar collector having increased energy rejection during stagnation is disclosed. The collector's glazing is brought into substantial contact with absorber during stagnation to increase re-emittance and thereby to maintan lower temperatures when the collector is not in operation.

  2. Solar collector apparatus having increased energy rejection during stagnation

    DOEpatents

    Moore, Stanley W.

    1983-07-12

    The disclosure relates to an active solar collector having increased energy rejection during stagnation. The collector's glazing is brought into substantial contact with absorber during stagnation to increase re-emittance and thereby to maintain lower temperatures when the collector is not in operation.

  3. Adsorption energy of small molecules on core-shell Fe@Au nanoparticles: tuning by shell thickness.

    PubMed

    Benoit, Magali; Tarrat, Nathalie; Morillo, Joseph

    2016-03-23

    The adsorption of several small molecules on different gold surfaces, Au(001), strained Au(001) and Au(001) epitaxied on Fe(001), has been characterized using density functional theory. The surface strain leads to a less energetically favourable adsorption for all studied molecules. Moreover, the presence of the iron substrate induces an additional decrease of the binding energy, for 1 and 2 Au monolayers. For carbon monoxide (CO), the structural and energetic variations with the number of Au monolayers deposited on Fe have been analyzed and correlated with the distance between the carbon atom and the gold surface. The effect of the subsurface layer has been evidenced for 1 and 2 monolayers. The other molecules show different quantitative behavior depending on the type of their interaction with the gold surface. However, the iron substrate weakens the interaction, either for the chemisorbed species or for the physisorbed species. 2 Au monolayers seem to be the best compromise to decrease the reactivity of the gold surface towards adsorption while preventing the Fe oxidation. PMID:26971708

  4. Can the Gibbs free energy of adsorption be predicted efficiently and accurately: an M05-2X DFT study.

    PubMed

    Michalkova, A; Gorb, L; Hill, F; Leszczynski, J

    2011-03-24

    This study presents new insight into the prediction of partitioning of organic compounds between a carbon surface (soot) and water, and it also sheds light on the sluggish desorption of interacting molecules from activated and nonactivated carbon surfaces. This paper provides details about the structure and interactions of benzene, polycyclic aromatic hydrocarbons, and aromatic nitrocompounds with a carbon surface modeled by coronene using a density functional theory approach along with the M05-2X functional. The adsorption was studied in vacuum and from water solution. The molecules studied are physisorbed on the carbon surface. While the intermolecular interactions of benzene and hydrocarbons are governed by dispersion forces, nitrocompounds are adsorbed also due to quite strong electrostatic interactions with all types of carbon surfaces. On the basis of these results, we conclude that the method of prediction presented in this study allows one to approach the experimental level of accuracy in predicting thermodynamic parameters of adsorption on a carbon surface from the gas phase. The empirical modification of the polarized continuum model leads also to a quantitative agreement with the experimental data for the Gibbs free energy values of the adsorption from water solution. PMID:21361266

  5. Linear solvation energy relationship for the adsorption of synthetic organic compounds on single-walled carbon nanotubes in water.

    PubMed

    Ding, H; Chen, C; Zhang, X

    2016-01-01

    The linear solvation energy relationship (LSER) was applied to predict the adsorption coefficient (K) of synthetic organic compounds (SOCs) on single-walled carbon nanotubes (SWCNTs). A total of 40 log K values were used to develop and validate the LSER model. The adsorption data for 34 SOCs were collected from 13 published articles and the other six were obtained in our experiment. The optimal model composed of four descriptors was developed by a stepwise multiple linear regression (MLR) method. The adjusted r(2) (r(2)adj) and root mean square error (RMSE) were 0.84 and 0.49, respectively, indicating good fitness. The leave-one-out cross-validation Q(2) ([Formula: see text]) was 0.79, suggesting the robustness of the model was satisfactory. The external Q(2) ([Formula: see text]) and RMSE (RMSEext) were 0.72 and 0.50, respectively, showing the model's strong predictive ability. Hydrogen bond donating interaction (bB) and cavity formation and dispersion interactions (vV) stood out as the two most influential factors controlling the adsorption of SOCs onto SWCNTs. The equilibrium concentration would affect the fitness and predictive ability of the model, while the coefficients varied slightly. PMID:26854726

  6. Low-energy proton increases associated with interplanetary shock waves.

    NASA Technical Reports Server (NTRS)

    Palmeira, R. A. R.; Allum, F. R.; Rao, U. R.

    1971-01-01

    Impulsive increases in the low energy proton flux observed by the Explorer 34 satellite, in very close time association with geomagnetic storm sudden commencements are described. It is shown that these events are of short duration (20-30 min) and occur only during the decay phase of a solar cosmic-ray flare event. The differential energy spectrum and the angular distribution of the direction of arrival of the particles are discussed. Two similar increases observed far away from the earth by the Pioneer 7 and 8 deep-space probes are also presented. These impulsive increases are compared with Energetic Storm Particle events and their similarities and differences are discussed. A model is suggested to explain these increases, based on the sweeping and trapping of low energy cosmic rays of solar origin by the advancing shock front responsible for the sudden commencement detected on the earth.

  7. Industrial Assessment Centers - Small Manufacturers Reduce Energy & Increase Productivity

    SciTech Connect

    2015-11-06

    Since 1976, the Industrial Assessment Centers (IACs), administered by the US Department of Energy, have supported small and medium-sized American manufacturers to reduce energy use and increase their productivity and competitiveness. The 24 IACs, located at premier engineering universities around the country (see below), send faculty and engineering students to local small and medium-sized manufacturers to provide no-cost assessments of energy use, process performance and waste and water flows. Under the direction of experienced professors, IAC engineering students analyze the manufacturer’s facilities, energy bills and energy, waste and water systems, including compressed air, motors/pumps, lighting, process heat and steam. The IACs then follow up with written energy-saving and productivity improvement recommendations, with estimates of related costs and payback periods.

  8. Characterization of volatile organic compound adsorption on multiwall carbon nanotubes under different levels of relative humidity using linear solvation energy relationship.

    PubMed

    Li, Mei-Syue; Wu, Siang Chen; Shih, Yang-Hsin

    2016-09-01

    Multiwall carbon nanotubes (MWCNTs) have been used as an adsorbent for evaluating the gas/solid partitioning of selected volatile organic compounds (VOCs). In this study, 15 VOCs were probed to determine their gas/solid partitioning coefficient (LogKd) using inverse gas chromatography at different relative humidity (RH) levels. Interactions between MWCNTs and VOCs were analyzed by regressing the observed LogKd with the linear solvation energy relationship (LSER). The results demonstrate that the MWCNT carbonyl and carboxyl groups provide high adsorption capacity for the VOCs (LogKd 3.72-5.24g/kg/g/L) because of the π-/n-electron pair interactions and hydrogen-bond acidity. The increasing RH gradually decreased the LogKd and shifted the interactions to dipolarity/polarizability, hydrogen-bond basicity, and cavity formation. The derived LSER equations provided adequate fits of LogKd, which is useful for VOC-removal processes and fate prediction of VOC contaminants by MWCNT adsorption in the environment. PMID:27152974

  9. Advanced Nano-Composites for Increased Energy Efficiency

    SciTech Connect

    2009-05-01

    This factsheet describes a research project whose goal is to increase energy efficiency and operating lifetime of wear-intensive industrial components and systems by developing and commercializing a family of ceramic-based monolithic composites that have shown remarkable resistance to wear in laboratory tests.

  10. Crystal Structures, Surface Stability, and Water Adsorption Energies of La-Bastnäsite via Density Functional Theory and Experimental Studies

    DOE PAGESBeta

    Srinivasan, Sriram Goverapet; Shivaramaiah, Radha; Kent, Paul R. C.; Stack, Andrew G.; Navrotsky, Alexandra; Riman, Richard; Anderko, Andre; Bryantsev, Vyacheslav S.

    2016-07-11

    Bastnasite is a fluoro-carbonate mineral that is the largest source of rare earth elements such as Y, La and Ce. With increasing demand for REE in many emerging technologies, there is an urgent need for improving the efficiency of ore beneficiation by froth flotation. In order to design improved flotation agents that can selectively bind to the mineral surface, a fundamental understanding of the bulk and surface properties of bastnasite is essential. Density functional theory calculations using the PBEsol exchange correlation functional and the DFT-D3 dispersion correction reveal that the most stable form of La bastnsite is isomorphic to themore » structure of Ce bastnasite belonging to the P2c space group, while the Inorganic Crystal Structure Database structure in the P2m space group is ca. 11.3 kJ/mol higher in energy per LaFCO3 formula unit. We report powder X-ray diffraction measurements on synthetic of La bastnasite to support these theoretical findings. Six different surfaces are studied by DFT, namely [100], [0001], [101], [102], [104] and [112]. Among these, the [100] surface is the most stable with a surface energy of 0.73 J/m2 in vacuum and 0.45 J/m2 in aqueous solution. We predicted the shape of a La bastnasite nanoparticle via thermodynamic Wulff construction to be a hexagonal prism with [100] and [0001] facets, chiseled at its ends by the [101] and [102] facets. The average surface energy of the nanoparticle in the gas phase is estimated to be 0.86 J/m2, in good agreement with a value of 1.11 J/m2 measured by calorimetry. The calculated adsorption energy of a water molecule varies widely with the surface plane and specific adsorption sites on a given surface. Moreover, the first layer of water molecules is predicted to adsorb strongly on the La-bastnasite surface, in agreement with water adsorption calorimetry experiments. Our work provides an important step towards a detailed atomistic understanding of the bastnasite water interface and designing

  11. Light Increases Energy Transfer Efficiency in a Boreal Stream

    PubMed Central

    Lesutienė, Jūratė; Gorokhova, Elena; Stankevičienė, Daiva; Bergman, Eva; Greenberg, Larry

    2014-01-01

    Periphyton communities of a boreal stream were exposed to different light and nutrient levels to estimate energy transfer efficiency from primary to secondary producers using labeling with inorganic 13C. In a one-day field experiment, periphyton grown in fast-flow conditions and dominated by opportunistic green algae were exposed to light levels corresponding to sub-saturating (forest shade) and saturating (open stream section) irradiances, and to N and P nutrient additions. In a two-week laboratory experiment, periphyton grown in low-flow conditions and dominated by slowly growing diatoms were incubated under two sub-saturating light and nutrient enrichment levels as well as grazed and non-grazed conditions. Light had significant positive effect on 13C uptake by periphyton. In the field experiment, P addition had a positive effect on 13C uptake but only at sub-saturating light levels, whereas in the laboratory experiment nutrient additions had no effect on the periphyton biomass, 13C uptake, biovolume and community composition. In the laboratory experiment, the grazer (caddisfly) effect on periphyton biomass specific 13C uptake and nutrient content was much stronger than the effects of light and nutrients. In particular, grazers significantly reduced periphyton biomass and increased biomass specific 13C uptake and C:nutrient ratios. The energy transfer efficiency, estimated as a ratio between 13C uptake by caddisfly and periphyton, was positively affected by light conditions, whereas the nutrient effect was not significant. We suggest that the observed effects on energy transfer were related to the increased diet contribution of highly palatable green algae, stimulated by higher light levels. Also, high heterotrophic microbial activity under low light levels would facilitate energy loss through respiration and decrease overall trophic transfer efficiency. These findings suggest that even a small increase in light intensity could result in community-wide effects on

  12. Increasing the energy of the Fermilab Tevatron accelerator

    SciTech Connect

    Fuerst, J.D.; Theilacker, J.C.

    1994-07-01

    The superconducting Tevatron accelerator at Fermilab has reached its eleventh year of operation since being commissioned in 1983. Last summer, four significant upgrades to the cryogenic system became operational which allow Tevatron operation at higher energy. This came after many years of R&D, power testing in sectors (one sixth) of the Tevatron, and final system installation. The improvements include the addition of cold helium vapor compressors, supporting hardware for subatmospheric operation, a new satellite refrigerator control system, and a higher capacity central helium liquefier. A description of each cryogenic upgrade, commissioning experience, and attempts to increase the energy of the Tevatron are presented.

  13. Adsorption of alkali metals on Ge(001)(2×1) surface

    SciTech Connect

    Xiao, H Y.; Zu, Xiaotao; Zhang, Yanfeng; Gao, Fei

    2006-01-09

    Ab initio total energy calculations have been performed for Na, K and Rb adsorption on Ge(001)(2?1) surface. It was found that the adsorption site of AM is AM size dependent. Structural analysis showed that the Ge-Ge dimer bond becomes stronger with increasing AM size. As the coverage increases from 0.5 to 1 ML it turns out that no depolarization effect occurs upon Na adsorption, while this effect become more important with increasing AM size. We also found that for all adsorption systems investigated the germanium surface is metallic and semiconducting for the coverage of 0.5 and 1 ML, respectively.

  14. Can Energy Drinks Increase the Desire for More Alcohol?1234

    PubMed Central

    Marczinski, Cecile A

    2015-01-01

    Energy drinks, the fastest growing segment in the beverage market, have become popular mixers with alcohol. The emerging research examining the use of alcohol mixed with energy drinks (AmEDs) indicates that the combination of caffeine-containing energy drinks with alcohol may be riskier than the use of alcohol alone. The public health concerns arising from AmED use are documented in different research domains. Epidemiologic studies reveal that the consumption of AmEDs is frequent among young and underage drinkers, demographic groups that are more likely to experience the harms and hazards associated with alcohol use. In addition, for all consumers, elevated rates of binge drinking and risk of alcohol dependence have been associated with AmED use when compared to alcohol alone. Results from laboratory studies help explain why AmED use is associated with excessive intake of alcohol. When an energy drink (or caffeine) is combined with alcohol, the desire (or urge) to drink more alcohol is more pronounced in both humans and animals than with the same dose of alcohol alone. The experience of drinking alcohol appears to be more rewarding when combined with energy drinks. Given that caffeine in other foods and beverages increases preference for those products, further research on AmEDs may elucidate the underlying mechanisms that contribute to alcohol dependence. PMID:25593148

  15. Can energy drinks increase the desire for more alcohol?

    PubMed

    Marczinski, Cecile A

    2015-01-01

    Energy drinks, the fastest growing segment in the beverage market, have become popular mixers with alcohol. The emerging research examining the use of alcohol mixed with energy drinks (AmEDs) indicates that the combination of caffeine-containing energy drinks with alcohol may be riskier than the use of alcohol alone. The public health concerns arising from AmED use are documented in different research domains. Epidemiologic studies reveal that the consumption of AmEDs is frequent among young and underage drinkers, demographic groups that are more likely to experience the harms and hazards associated with alcohol use. In addition, for all consumers, elevated rates of binge drinking and risk of alcohol dependence have been associated with AmED use when compared to alcohol alone. Results from laboratory studies help explain why AmED use is associated with excessive intake of alcohol. When an energy drink (or caffeine) is combined with alcohol, the desire (or urge) to drink more alcohol is more pronounced in both humans and animals than with the same dose of alcohol alone. The experience of drinking alcohol appears to be more rewarding when combined with energy drinks. Given that caffeine in other foods and beverages increases preference for those products, further research on AmEDs may elucidate the underlying mechanisms that contribute to alcohol dependence. PMID:25593148

  16. Characterization of Adsorption Enthalpy of Novel Water-Stable Zeolites and Metal-Organic Frameworks

    PubMed Central

    Kim, Hyunho; Cho, H. Jeremy; Narayanan, Shankar; Yang, Sungwoo; Furukawa, Hiroyasu; Schiffres, Scott; Li, Xiansen; Zhang, Yue-Biao; Jiang, Juncong; Yaghi, Omar M.; Wang, Evelyn N.

    2016-01-01

    Water adsorption is becoming increasingly important for many applications including thermal energy storage, desalination, and water harvesting. To develop such applications, it is essential to understand both adsorbent-adsorbate and adsorbate-adsorbate interactions, and also the energy required for adsorption/desorption processes of porous material-adsorbate systems, such as zeolites and metal-organic frameworks (MOFs). In this study, we present a technique to characterize the enthalpy of adsorption/desorption of zeolites and MOF-801 with water as an adsorbate by conducting desorption experiments with conventional differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA). With this method, the enthalpies of adsorption of previously uncharacterized adsorbents were estimated as a function of both uptake and temperature. Our characterizations indicate that the adsorption enthalpies of type I zeolites can increase to greater than twice the latent heat whereas adsorption enthalpies of MOF-801 are nearly constant for a wide range of vapor uptakes. PMID:26796523

  17. Characterization of Adsorption Enthalpy of Novel Water-Stable Zeolites and Metal-Organic Frameworks

    NASA Astrophysics Data System (ADS)

    Kim, Hyunho; Cho, H. Jeremy; Narayanan, Shankar; Yang, Sungwoo; Furukawa, Hiroyasu; Schiffres, Scott; Li, Xiansen; Zhang, Yue-Biao; Jiang, Juncong; Yaghi, Omar M.; Wang, Evelyn N.

    2016-01-01

    Water adsorption is becoming increasingly important for many applications including thermal energy storage, desalination, and water harvesting. To develop such applications, it is essential to understand both adsorbent-adsorbate and adsorbate-adsorbate interactions, and also the energy required for adsorption/desorption processes of porous material-adsorbate systems, such as zeolites and metal-organic frameworks (MOFs). In this study, we present a technique to characterize the enthalpy of adsorption/desorption of zeolites and MOF-801 with water as an adsorbate by conducting desorption experiments with conventional differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA). With this method, the enthalpies of adsorption of previously uncharacterized adsorbents were estimated as a function of both uptake and temperature. Our characterizations indicate that the adsorption enthalpies of type I zeolites can increase to greater than twice the latent heat whereas adsorption enthalpies of MOF-801 are nearly constant for a wide range of vapor uptakes.

  18. Characterization of Adsorption Enthalpy of Novel Water-Stable Zeolites and Metal-Organic Frameworks.

    PubMed

    Kim, Hyunho; Cho, H Jeremy; Narayanan, Shankar; Yang, Sungwoo; Furukawa, Hiroyasu; Schiffres, Scott; Li, Xiansen; Zhang, Yue-Biao; Jiang, Juncong; Yaghi, Omar M; Wang, Evelyn N

    2016-01-01

    Water adsorption is becoming increasingly important for many applications including thermal energy storage, desalination, and water harvesting. To develop such applications, it is essential to understand both adsorbent-adsorbate and adsorbate-adsorbate interactions, and also the energy required for adsorption/desorption processes of porous material-adsorbate systems, such as zeolites and metal-organic frameworks (MOFs). In this study, we present a technique to characterize the enthalpy of adsorption/desorption of zeolites and MOF-801 with water as an adsorbate by conducting desorption experiments with conventional differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA). With this method, the enthalpies of adsorption of previously uncharacterized adsorbents were estimated as a function of both uptake and temperature. Our characterizations indicate that the adsorption enthalpies of type I zeolites can increase to greater than twice the latent heat whereas adsorption enthalpies of MOF-801 are nearly constant for a wide range of vapor uptakes. PMID:26796523

  19. 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

  20. 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.

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

    PubMed

    Yang, Shuang; Neimark, Alexander V

    2012-06-01

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

  2. [Adsorption Characteristics of Norfloxacin by Biochars Derived from Reed Straw and Municipal Sludge].

    PubMed

    Zhang, Han-yu; Wang, Zhao-wei; Gao, Jun-hong; Zhu, Jun-min; Xie, Chao-ran; Xie, Xiao-yun

    2016-02-15

    Two types of biochars were prepared by pyrolyzing reed straw and municipal sludge at the temperature of 500 degrees C. The structure and properties of biochars were characterized by BET, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and fourier transform infrared spectroscopy ( FTIR ). The effects of pH value, adsorption time, temperature and initial concentration of norfloxacin (NOR) on the adsorption behaviors were determined by single factor experiments, which were used to preliminarily discuss adsorption mechanism. The results showed that the adsorption of NOR onto biochars derived from reed straw and municipal sludge could reach 70% and 60% of the total adsorption within 12 h, respectively; the maximum adsorption capacities of the two biochars were 2.13 mg x g(-1) (biochar derived from reed straw) and 2.09 mg x g(-1) (biochar derived from municipal sludge). The quantities of both absorptions increased with the decreasing solution pH. The two adsorption kinetics of NOR onto biochars followed the pseudo second order kinetic equations, and adsorption isotherms fitted well with the Langmuir equations. Adsorption thermodynamics parameters such as Gibbs free energy (AG), enthalpy (AH) and entropy (AS) indicated that the two adsorptions were endothermic reactions. Infrared spectroscopy analysis indicated that oxygen-containing functional groups on biochars provided NOR molecules with adsorptive sites, which facilitated the formation of hydrogen bonds between NOR and the biochars. PMID:27363161

  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. I. Gas adsorption properties and porosity of transition metal-based cyanogels. II. Novel energy transfer processes in organic light-emitting devices

    NASA Astrophysics Data System (ADS)

    Deshpande, Rahul Shrikant

    The gas adsorption properties and porosity of cyanide-bridged transition metal-based gels are investigated in the first part of this dissertation. The cyanide bridges, connecting two transition metal centers, are characteristic of these gels; hence, these gels are termed cyanogels. Aerogel versus xerogel structures have a profound effect, both, on the thermodynamics and kinetics of gas adsorption on these cyanogels. Carbon dioxide is selectively adsorbed on palladium-cobalt-based cyanogels; the adsorption is fully reversible on both types of gels discussed. The thermodynamics and kinetics of the gas adsorption processes on these gels are analyzed here. From the ease and reproducibility of the CO2 desorption and the associated enthalpy values, it is concluded that CO2 is physisorbed on these gels. Both the adsorption and desorption processes are first-order in the gels. Adsorption of carbon monoxide on the palladium-cobalt cyanogels is also investigated. Unlike CO 2 physisorption, carbon monoxide is chemisorbed on these gels. An uptake of CO brings about a profound change in the xerogel morphology. The palladium-cobalt-based aerogels possess both micro- and mesoporosity; the xerogels are predominantly microporous with a narrow microporosity. The aerogel surfaces are found to be fractal as analyzed by gas adsorption. Unlike the aerogels, the xerogels do not possess surface fractality. The mechanism of adsorption of different gases on these gels is analyzed based on the gel morphologies. These transition metal-based gels are promising for a variety of applications such as heterogeneous catalysts, gas filters and magnetic materials. The porosity of these gels can be exploited to make gel-embedded filters to separate mixtures of gases based on the their differential adsorption propensities. The reversible adsorption of CO2 can be harnessed practically by using these gels as CO2 storage reservoirs. In the second part of this dissertation, the first, balanced, white

  5. Environmental implications of increased biomass energy use. Final report

    SciTech Connect

    Miles, T.R. Sr.; Miles, T.R. Jr.

    1992-03-01

    This study reviews the environmental implications of continued and increased use of biomass for energy to determine what concerns have been and need to be addressed and to establish some guidelines for developing future resources and technologies. Although renewable biomass energy is perceived as environmentally desirable compared with fossil fuels, the environmental impact of increased biomass use needs to be identified and recognized. Industries and utilities evaluating the potential to convert biomass to heat, electricity, and transportation fuels must consider whether the resource is reliable and abundant, and whether biomass production and conversion is environmentally preferred. A broad range of studies and events in the United States were reviewed to assess the inventory of forest, agricultural, and urban biomass fuels; characterize biomass fuel types, their occurrence, and their suitability; describe regulatory and environmental effects on the availability and use of biomass for energy; and identify areas for further study. The following sections address resource, environmental, and policy needs. Several specific actions are recommended for utilities, nonutility power generators, and public agencies.

  6. Triangular tessellation scheme for the adsorption free energy at the liquid-liquid interface: Towards nonconvex patterned colloids.

    PubMed

    de Graaf, Joost; Dijkstra, Marjolein; van Roij, René

    2009-11-01

    We present a numerical technique, namely, triangular tessellation, to calculate the free energy associated with the adsorption of a colloidal particle at a flat interface. The theory and numerical scheme presented here are sufficiently general to handle nonconvex patchy colloids with arbitrary surface patterns characterized by a wetting angle, e.g., amphiphilicity. We ignore interfacial deformation due to capillary, electrostatic, or gravitational forces, but the method can be extended to take such effects into account. It is verified that the numerical method presented is accurate and sufficiently stable to be applied to more general situations than presented in this paper. The merits of the tessellation method prove to outweigh those of traditionally used semianalytic approaches, especially when it comes to generality and applicability. PMID:20364983

  7. Adsorption of water vapor by homoionic montmorillonites: Heats of adsorption and desorption

    SciTech Connect

    Dios Cancela, G.; Huertas, F.J.; Romero Taboada, E.; Sanchez-Rasero, F.; Hernandez Laguna, A.

    1997-01-15

    Adsorption isotherms for water vapor, basal spacing, and immersion heats and water desorption heats of Li{sup +}, Na{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cu{sup 2+}, and Fe{sup 3+} montmorillonite are measured at various relative humidities (r.h.). The amount of water adsorbed as a function of r.h. is found to increase gradually, whereas basal spacing increases and the adsorption heat decreases in steps. The water desorption heat also decreases in steps. The entropy of adsorbed water appears to be negative with respect to the entropy of liquid water. A theoretical model is proposed to describe the hydration process of Li{sup +}, Na{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cu{sup 2+}, and Fe{sup 3+} montmorillonites. The experimental adsorption heats are found to have a direct relationship with the sum of the hydration energy of the cations plus expansion energy.

  8. A Density Functional Theory Study of Formaldehyde Adsorption on Ceria

    SciTech Connect

    Mei, Donghai; Deskins, N. Aaron; Dupuis, Michel

    2007-11-01

    Molecular adsorption of formaldehyde on the stoichiometric CeO2(111) and CeO2(110) surfaces was studied using periodic density functional theory. Two adsorption modes (strong chemisorbed and weak physisorbed) were identified on both surfaces. This is consistent with recent experimental observations. On the (111) surface, formaldehyde strongly chemisorbs with an adsorption energy of 0.86 eV to form a dioxymethylene-like structure, in which a surface O lifts from the surface to bind with the C of formaldehyde. A weak physisorbed state with adsorption energy of 0.28 eV was found with the O of formaldehyde interacting with a surface Ce. On the (110) surface, dioxymethyelene formation was also observed, with an adsorption energy of 1.31 eV. The weakly adsorbed state of formaldehyde on the (110) surface was energetically comparable to the weak adsorption state on the (111) surface, but adsorption occurred through a formaldehyde C and surface O interaction. Analysis of the local density of states and charge density differences after adsorption shows that strong covalent bonding occurs between the C of formaldehyde and surface O when dioxymethylene forms. Calculated vibrational frequencies also confirm dioxymethylene formation. Our results also show that as the coverage increases, the adsorption of formaldehyde on the (111) surface becomes weak, but is nearly unaffected on the (110) surface. This work was supported by a Laboratory Directed Research and Development (LDRD) project of the Pacific Northwest National Laboratory (PNNL). The computations were performed using the Molecular Science Computing Facility in the William R. Wiley Environmental Molecular Sciences Laboratory, which is a U.S. Department of Energy national scientific user facility located at PNNL in Richland, Washington. Computing time was made under a Computational Grand Challenge “Computational Catalysis”. Part of the computing time was also granted by the National Energy Research Scientific Computing

  9. Adsorption energy and spin state of first-row transition metals adsorbed on MgO(100)

    NASA Astrophysics Data System (ADS)

    Markovits, A.; Paniagua, J. C.; López, N.; Minot, C.; Illas, F.

    2003-03-01

    Slab and cluster model spin-polarized calculations have been carried out to study various properties of isolated first-row transition metal atoms adsorbed on the anionic sites of the regular MgO(100) surface. The calculated adsorption energies follow the trend of the metal cohesive energies, indicating that the changes in the metal-support and metal-metal interactions along the series are dominated by atomic properties. In all cases, except for Ni at the generalized gradient approximation level, the number of unpaired electron is maintained as in the isolated metal atom. The energy required to change the atomic state from high to low spin has been computed using the PW91 and B3LYP density-functional-theory-based methods. PW91 fails to predict the proper ground state of V and Ni, but the results for the isolated and adsorbed atom are consistent within the method. B3LYP properly predicts the ground state of all first-row transition atom the high- to low-spin transition considered is comparable to experiment. In all cases, the interaction with the surface results in a reduced high- to low-spin transition energy.

  10. Adsorption behaviour of direct yellow 50 onto cotton fiber: equilibrium, kinetic and thermodynamic profile.

    PubMed

    Ismail, L F M; Sallam, H B; Abo Farha, S A; Gamal, A M; Mahmoud, G E A

    2014-10-15

    This study investigated the adsorption of direct yellow 50 onto cotton fiber from aqueous solution by using parameters, such as pH, temperature, contact time, initial dye concentration and the effect of sodium sulphate, tetrasodium edate and trisodium citrate. The extent of dye adsorption increased with increasing contact time, temperature and solution concentration. The experimental data were analyzed by the Langmuir and Freundlich models of adsorption. It was found that the Langmuir equation fit better than the Freundlich equation. The results show that the presence of SE and SC significantly enhance the dye adsorption onto cotton fiber. In addition, the adsorption data obtained at different temperatures of DY50 onto cotton fiber were applied to pseudo first-order, pseudo second-order and intraparticle diffusion models. The rates of adsorption were found to conform to pseudo second-order kinetics with good correlation. Also, free energy of adsorption (ΔG(#)), enthalpy (ΔH(#)), and entropy (ΔS(#)) changes were determined to predict the nature of adsorption. The positive value of the enthalpy change indicated that the adsorption is endothermic process. The activation energy, Ea, is ranged between 1.9 and 3.9kJmol(-1) indicated that the adsorption process is a physisorption. This low value of Ea generally indicates diffusion controlled process. PMID:24882703

  11. The role of vdW interactions in coverage dependent adsorption energies of atomic adsorbates on Pt(111) and Pd(111)

    NASA Astrophysics Data System (ADS)

    Thirumalai, Hari; Kitchin, John R.

    2016-08-01

    Adsorption, a fundamental process in heterogeneous catalysis is known to be dependent on the adsorbate-adsorbate and surface-adsorbate bonds. van der Waals (vdW) interactions are one of the types of interactions that have not been examined thoroughly as a function of adsorbate coverage. In this work we quantify the vdW interactions for atomic adsorbates on late transition metal surfaces, and determine how these long range forces affect the coverage dependent adsorption energies. We calculate the adsorption energies of carbon, nitrogen, oxygen, sulfur, fluorine, bromine and chlorine species on Pt(111) and Pd(111) at coverages ranging from 1/4 to 1 ML using the BEEF-vdW functional. We observe that adsorption energies remain coverage dependent, and this coverage dependence is shown to be statistically significant. vdW interactions are found to be coverage dependent, but more significantly, they are found to be dependent on molecular properties such as adsorbate size, and consequently, correlate with the adsorbate effective nuclear charge. We observe that these interactions account for a reduction in the binding energy of the system, due to the destabilizing attractive interactions between the adsorbates which weaken its bond with the surface.

  12. Adsorption of CO Molecules on Si(001) at Room Temperature

    NASA Astrophysics Data System (ADS)

    Seo, Eonmi; Eom, Daejin; Kim, Hanchul; Koo, Ja-Yong

    2015-03-01

    Initial adsorption of CO molecules on Si(001) is investigated by using room-temperature (RT) scanning tunneling microscopy (STM) and density functional theory calculations. Theoretical calculations show that only one adsorption configuration of terminal-bond CO (T-CO) is stable and that the bridge-bond CO is unstable. All the abundantly observed STM features due to CO adsorption can be identified as differently configured T-COs. The initial sticking probability of CO molecules on Si(001) at RT is estimated to be as small as ~ 1 x 10-4 monolayer/Langmuir, which is significantly increased at high-temperature adsorption experiments implying a finite activation barrier for adsorption. Thermal annealing at 900 K for 5 min results in the dissociation of the adsorbed CO molecules with the probability of 60-70% instead of desorption, indicating both a strong chemisorption state and an activated dissociation process. The unique adsorption state with a large binding energy, a tiny sticking probability, and a finite adsorption barrier is in stark contrast with the previous low-temperature (below 100 K) observations of a weak binding, a high sticking probability, and a barrierless adsorption. We speculate that the low-temperature results might be a signature of a physisorption state in the condensed phase.

  13. [Adsorption of Congo red from aqueous solution on hydroxyapatite].

    PubMed

    Zhan, Yan-Hui; Lin, Jian-Wei

    2013-08-01

    The adsorption of Congo red (CR) from aqueous solution on hydroxyapatite was investigated using batch experiments. The hydroxyapatite was effective for CR removal from aqueous solution. The adsorption kinetics of CR on hydroxyapatite well followed a pseudo-second-order model. The equilibrium adsorption data of CR on hydroxyapatite could be described by the Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. Thermodynamic parameters such as Gibbs free energy change, enthalpy change and entropy change were calculated and showed that the adsorption of CR on hydroxyapatite was spontaneous and exothermic in nature. The CR adsorption capacity for hydroxyapatite decreased significantly with increasing pH from 8 to 10. Thermal regeneration showed that hydroxyapatite could be used for six desorption-adsorption cycles with high removal efficiency for CR in each cycle. The mechanisms for CR adsorption on hydroxyapatite with pH value below the pH at point of zero charge (pH(PZC)) include electrostatic attraction, hydrogen bonding and Lewis acid-base interaction. The mechanisms for CR adsorption on hydroxyapatite with pH value above its pH(PZC) include hydrogen bonding and Lewis acid-base interaction. Results of this work indicate that hydroxyapatite is a promising adsorbent for CR removal from aqueous solution. PMID:24191561

  14. Understanding the adsorption mechanism of chitosan onto poly(lactide-co-glycolide) particles

    PubMed Central

    Guo, Chunqiang; Gemeinhart, Richard A.

    2008-01-01

    Polyelectrolyte-coated nanoparticles or microparticles interact with bioactive molecules (peptides, proteins or nucleic acids) and have been proposed as delivery systems for these molecules. However, the mechanism of adsorption of polyelectrolyte onto particles remains unsolved. In this study, cationic poly(lactide-co-glycolide) (PLGA) nanoparticles were fabricated by adsorption of various concentrations of a biodegradable polysaccharide, chitosan (0–2.4 g/L), using oil-in-water emulsion and solvent evaporation techniques. The particle diameter, zeta-potential, and chitosan adsorption of chitosan coated PLGA nanoparticles confirmed the increase of polyelectrolyte adsorption. Five adsorption isotherm models (Langmuir, Freundlich, Halsey, Henderson and Smith) were applied to the experimental data in order to better understand the mechanism of adsorption. Both particle diameter and chitosan adsorption increased with chitosan concentration during adsorption. A good correlation was obtained between PLGA-chitosan nanoparticle size and adsorbed chitosan on the surface, suggesting the increased particle size was primarily due to the increased chitosan adsorption. The zeta-potential of chitosan-coated PLGA nanoparticles was positive and increased with chitosan adsorbed until a maximum value (+55 mV) was reached at approximately 0.4–0.6 g/L; PLGA nanoparticles had a negative zeta-potential (−20 mV) prior to chitosan adsorption. Chitosan adsorption on PLGA nanoparticles followed a multilayer adsorption behavior, although the Langmuir monolayer equation held at low concentrations of chitosan. The underlying reasons for adsorption of chitosan on PLGA nanoparticles were thought to be the cationic nature of chitosan, high surface energy and microporous non-uniform surface of PLGA nanoparticles. PMID:18602994

  15. Adsorption and interaction energy of π ethene on Pt(1 1 1) and Pt alloys: A detailed analysis of vibrational, energetic and electronic properties

    NASA Astrophysics Data System (ADS)

    Haubrich, J.; Becker, C.; Wandelt, K.

    2009-06-01

    We present a detailed analysis of the electronic and geometric bonding properties of the model alkene ethene on different mono- and bimetallic surfaces to establish the difference between adsorption energy and interaction energy and to elucidate the chemical character of a single platinum atom in different chemical environments. The adsorption of ethene on Pt(1 1 1) at 100 K leads to two adsorption states, which are commonly described as being of di- σ-type (bidentate, μ 2η 2) and π-type (monodentate, μ 1η 2). While the later is the minority species on Pt(1 1 1) it is of larger abundance on the platinum alloys. We have chosen π-bonded ethene for our study since it can be found on Pt(1 1 1), the Pt 3Sn and Pt 2Sn surface alloys, and Cu 3Pt(1 1 1). Density functional theory calculations of the adsorption structures, site and decomposed densities of states, as well as partial charge densities in conjunction with vibrational spectroscopy show that the bonding, i.e. the interaction energy, of the π ethene is only weakly influenced by alloying. Even in a copper matrix - as in the case of Cu 3Pt(1 1 1) - the bonding platinum atom essentially keeps its chemical identity and the interaction energy is reduced by only 14% compared to Pt(1 1 1). This observation suggests that bonding on surfaces is a strongly localized phenomenon. However, the adsorption energy decreases significantly due to alloying, which is attributed to the varying local relaxation of the different metal surfaces.

  16. Densely-packed ZnTPPs Monolayer on the Rutile TiO2(110)-(1×1) Surface: Adsorption Behavior and Energy Level Alignment

    PubMed Central

    Rangan, Sylvie; Ruggieri, Charles; Bartynski, Robert; Martínez, José Ignacio; Flores, Fernando; Ortega, José

    2016-01-01

    The adsorption of a densely packed Zinc(II) tetraphenylporphyrin monolayer on a rutile TiO2(110)-(1×1) surface has been studied using a combination of experimental and theoretical methods, aimed at analyzing the relation between adsorption behavior and barrier height formation. The adsorption configuration of ZnTPP was determined from scanning tunnel microscopy (STM) imaging, density functional theory (DFT) calculations and STM image simulation. The corresponding energy alignment was experimentally determined from X-ray and UV-photoemission spectroscopies and inverse photoemission spectroscopy. These results were found in good agreement with an appropriately corrected DFT model, pointing to the importance of local bonding and intermolecular interactions in the establishment of barrier heights. PMID:26998188

  17. How Schools Can Control the Increasing Cost of Energy.

    ERIC Educational Resources Information Center

    Levy, Hans F.

    In a nontechnical way, this small book outlines the present use of energy in schools, what forms of energy will be available in the foreseeable future, how energy is presently wasted in educational facilities, and how energy can be conserved now and in the future. The school administrator can control the energy consumption in his schools and this…

  18. Combining total energy and energy industrial center concepts to increase utilization efficiency of geothermal energy

    NASA Technical Reports Server (NTRS)

    Bayliss, B. P.

    1974-01-01

    Integrating energy production and energy consumption to produce a total energy system within an energy industrial center which would result in more power production from a given energy source and less pollution of the environment is discussed. Strong governmental support would be required for the crash drilling program necessary to implement these concepts. Cooperation among the federal agencies, power producers, and private industry would be essential in avoiding redundant and fruitless projects, and in exploiting most efficiently our geothermal resources.

  19. Budget Increases Proposed for NOAA and Energy Department

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2009-05-01

    In addition to the Obama administration's proposed budget increases for NASA, the Environmental Protection Agency, and the U.S. Geological Survey (see Eos, 90(10), 83, 2009, and 90(20), 175, 2009), other federal Earth and space science agencies also would receive boosts in the proposed fiscal year (FY) 2010 budget. The proposed budget comes on top of the 2009 American Recovery and Reinvestment Act's (ARRA) US$18.3 billion in stimulus spending for research and development that can be apportioned between the FY 2009 and FY 2010 budgets. This news item focuses on the budget proposals for the National Oceanic and Atmospheric Administration (NOAA) and the Department of Energy (DOE). Next week, Eos will look at the budget proposal for the National Science Foundation.

  20. Tandem photovoltaic solar cells and increased solar energy conversion efficiency

    NASA Technical Reports Server (NTRS)

    Loferski, J. J.

    1976-01-01

    Tandem photovoltaic cells, as proposed by Jackson (1955) to increase the efficiency of solar energy conversion, involve the construction of a system of stacked p/n homojunction photovoltaic cells composed of different semiconductors. It had been pointed out by critics, however, that the total power which could be extracted from the cells in the stack placed side by side was substantially greater than the power obtained from the stacked cells. A reexamination of the tandem cell concept in view of the development of the past few years is conducted. It is concluded that the use of tandem cell systems in flat plate collectors, as originally envisioned by Jackson, may yet become feasible as a result of the development of economically acceptable solar cells for large scale terrestrial power generation.

  1. Advanced Wear-resistant Nanocomposites for Increased Energy Efficiency

    SciTech Connect

    Cook, B. A.; Harringa, J. L.; Russel, A. M.

    2012-12-01

    This report summarizes the work performed by an Ames-led project team under a 4-year DOE-ITP sponsored project titled, 'Advanced Wear-resistant Nanocomposites for Increased Energy Efficiency.' The Report serves as the project deliverable for the CPS agreement number 15015. The purpose of this project was to develop and commercialize a family of lightweight, bulk composite materials that are highly resistant to degradation by erosive and abrasive wear. These materials, based on AlMgB{sub 14}, are projected to save over 30 TBtu of energy per year when fully implemented in industrial applications, with the associated environmental benefits of eliminating the burning of 1.5 M tons/yr of coal and averting the release of 4.2 M tons/yr of CO{sub 2} into the air. This program targeted applications in the mining, drilling, machining, and dry erosion applications as key platforms for initial commercialization, which includes some of the most severe wear conditions in industry. Production-scale manufacturing of this technology has begun through a start-up company, NewTech Ceramics (NTC). This project included providing technical support to NTC in order to facilitate cost-effective mass production of the wear-resistant boride components. Resolution of issues related to processing scale-up, reduction in energy intensity during processing, and improving the quality and performance of the composites, without adding to the cost of processing were among the primary technical focus areas of this program. Compositional refinements were also investigated in order to achieve the maximum wear resistance. In addition, synthesis of large-scale, single-phase AlMgB{sub 14} powder was conducted for use as PVD sputtering targets for nanocoating applications.

  2. Adsorption of sulfur dioxide on ammonia-treated activated carbon fibers

    USGS Publications Warehouse

    Mangun, C.L.; DeBarr, J.A.; Economy, J.

    2001-01-01

    A series of activated carbon fibers (ACFs) and ammonia-treated ACFs prepared from phenolic fiber precursors have been studied to elucidate the role of pore size, pore volume, and pore surface chemistry on adsorption of sulfur dioxide and its catalytic conversion to sulfuric acid. As expected, the incorporation of basic functional groups into the ACFs was shown as an effective method for increasing adsorption of sulfur dioxide. The adsorption capacity for dry SO2 did not follow specific trends; however the adsorption energies calculated from the DR equation were found to increase linearly with nitrogen content for each series of ACFs. Much higher adsorption capacities were achieved for SO2 in the presence of oxygen and water due to its catalytic conversion to H2SO4. The dominant factor for increasing adsorption of SO2 from simulated flue gas for each series of fibers studied was the weight percent of basic nitrogen groups present. In addition, the adsorption energies calculated for dry SO2 were shown to be linearly related to the adsorption capacity of H2SO4 from this flue gas for all fibers. It was shown that optimization of this parameter along with the pore volume results in higher adsorption capacities for removal of SO2 from flue gases. ?? 2001 Elsevier Science Ltd. All rights reserved.

  3. Adsorption of selenium by amorphous iron oxyhydroxide and manganese dioxide

    USGS Publications Warehouse

    Balistrieri, L.S.; Chao, T.T.

    1990-01-01

    is reflected in decreasing equilibrium constants for selenite with increasing adsorption density and both experimental observations and modeling results suggest that manganese dioxide has fewer sites of higher energy for selenite adsorption than amorphous iron oxyhydroxide. Modeling and interpreting the adsorption of phosphate, molybdate, and silicate on the oxides are made difficult by the lack of constraint in choosing surface species and the fact that equally good fits can be obtained with different surface species. Finally, predictions of anion competition using the model results from single adsorbate systems are not very successful because the model does not account for surface site heterogeneity. Selenite adsorption data from a multi-adsorbate system could be fit if the equilibrium constant for selenite is decreased with increasing anion adsorption density. ?? 1990.

  4. Means of increasing efficiency of CPC solar energy collector

    DOEpatents

    Chao, Bei Tse; Rabl, Ari

    1977-02-15

    A device is provided for improving the thermal efficiency of a cylindrical radiant energy collector. A channel is placed next to and in close proximity to the nonreflective side of an energy reflective wall of a cylindrical collector. A coolant is piped through the channel and removes a portion of the nonreflective energy incident on the wall which is absorbed by the wall. The energy transferred to the coolant may be utilized in a useful manner.

  5. Means of increasing efficiency of CPC solar energy collector

    DOEpatents

    Chao, B.T.; Rabl, A.

    1975-06-27

    A device is provided for improving the thermal efficiency of a cylindrical radiant energy collector. A channel is placed next to and in close proximity to the nonreflective side of an energy reflective wall of a cylindrical collector. A coolant is piped through the channel and removes a portion of the nonreflective energy incident on the wall which is absorbed by the wall. The energy transferred to the coolant may be utilized in a useful manner.

  6. Theoretical studies of the adsorption of hydroxymethylidyne (COH) on Pt-alloy surfaces using density functional theory

    NASA Astrophysics Data System (ADS)

    Cahyanto, Wahyu Tri; Widanarto, Wahyu; Shukri, Ganes; Kasai, Hideaki

    2016-02-01

    We present density functional calculations for the adsorption of hydroxymethylidyne (COH) on Pt, PtRu, and PtRuMo (111) surfaces. Here we clarify the adsorption mechanism by using a charge transfer analysis related to the adsorption energy. We observe that the preferred binding sites for COH are the hcp hollow Pt-Pt-Pt, hcp hollow Pt-Ru-Pt, and hcp hollow Pt-Ru-Pt adsorption sites for Pt, PtRu, and PtRuMo, respectively. Addition of Ru to form a PtRu surface increases the adsorption energy, while addition of Mo to form a PtRuMo surface decreases it. Our analyses show that the adsorption energy is determined by electron transfer between the molecular COH and the metal surfaces associated with bonding.

  7. Charge induced enhancement of adsorption for hydrogen storage materials

    NASA Astrophysics Data System (ADS)

    Sun, Xiang

    2009-12-01

    The rising concerns about environmental pollution and global warming have facilitated research interest in hydrogen energy as an alternative energy source. To apply hydrogen for transportations, several issues have to be solved, within which hydrogen storage is the most critical problem. Lots of materials and devices have been developed; however, none is able to meet the DOE storage target. The primary issue for hydrogen physisorption is a weak interaction between hydrogen and the surface of solid materials, resulting negligible adsorption at room temperature. To solve this issue, there is a need to increase the interaction between the hydrogen molecules and adsorbent surface. In this study, intrinsic electric dipole is investigated to enhance the adsorption energy. The results from the computer simulation of single ionic compounds with hydrogen molecules to form hydrogen clusters showed that electrical charge of substances plays an important role in generation of attractive interaction with hydrogen molecules. In order to further examine the effects of static interaction on hydrogen adsorption, activated carbon with a large surface area was impregnated with various ionic salts including LiCl, NaCl, KCl, KBr, and NiCl2 and their performance for hydrogen storage was evaluated by using a volumetric method. Corresponding computer simulations have been carried out by using DFT (Density Functional Theory) method combined with point charge arrays. Both experimental and computational results prove that the adsorption capacity of hydrogen and its interaction with the solid materials increased with electrical dipole moment. Besides the intrinsic dipole, an externally applied electric field could be another means to enhance hydrogen adsorption. Hydrogen adsorption under an applied electric field was examined by using porous nickel foil as electrodes. Electrical signals showed that adsorption capacity increased with the increasing of gas pressure and external electric voltage

  8. New findings on the influence of carbon surface curvature on energetics of benzene adsorption from gaseous phase

    NASA Astrophysics Data System (ADS)

    Terzyk, Artur P.; Furmaniak, Sylwester; Wiśniewski, Marek; Werengowska, Karolina; Gauden, Piotr A.; Kowalczyk, Piotr

    2016-02-01

    In this Letter, new results of calorimetric study on benzene adsorption from the gaseous phase are presented. According to some of recently published reports, the energy of solid-fluid, interactions increases with the rise in carbon nanotube curvature during adsorption. The recent considerations [Chem. Phys. Lett. 619 (2015) 219] on thermodynamics of adsorption from aqueous solutions on a series of carbon nanotubes have confirmed this observation. Although comparable 'energy-tube diameter' relations for benzene adsorption from the solution and from the gaseous phase are observed, remarkable differences between the mechanisms of the both processes caused by surface heterogeneity are noticeable.

  9. Fabrication of Low Adsorption Energy Ni-Mo Cluster Cocatalyst in Metal-Organic Frameworks for Visible Photocatalytic Hydrogen Evolution.

    PubMed

    Zhen, Wenlong; Gao, Haibo; Tian, Bin; Ma, Jiantai; Lu, Gongxuan

    2016-05-01

    An effective cocatalyst is crucial for enhancing the visible photocatalytic performance of the hydrogen generation reaction. By using density-functional theory (DFT) and frontier molecular orbital (FMO) theory calculation analysis, the hydrogen adsorption free energy (ΔGH) of Ni-Mo alloy (458 kJ·mol(-1)) is found to be lower than that of Ni itself (537 kJ·mol(-1)). Inspired by these results, the novel, highly efficient cocatalyst NiMo@MIL-101 for photocatalysis of the hydrogen evolution reaction (HER) was fabricated using the double solvents method (DSM). In contrast with Ni@MIL-101 and Mo@MIL-101, NiMo@MIL-101 exhibited an excellent photocatalytic performance (740.2 μmol·h(-1) for HER), stability, and high apparent quantum efficiency (75.7%) under 520 nm illumination at pH 7. The NiMo@MIL-101 catalyst also showed a higher transient photocurrent, lower overpotential (-0.51 V), and longer fluorescence lifetime (1.57 ns). The results uncover the dependence of the photocatalytic activity of HER on the ΔGH of Ni-Mo (MoNi4) alloy nanoclusters, i.e., lower ΔGH corresponding to higher HER activity for the first time. The NiMo@MIL-101 catalyst could be a promising candidate to replace precious-metal catalysts of the HER. PMID:27070204

  10. Co-adsorption of phosphate and zinc(II) on the surface of ferrihydrite.

    PubMed

    Liu, Jing; Zhu, Runliang; Xu, Tianyuan; Xu, Yin; Ge, Fei; Xi, Yunfei; Zhu, Jianxi; He, Hongping

    2016-02-01

    Ferrihydrite (Fh) is of great importance in affecting the migration and transformation of heavy-metal cations and oxyanions. To advance the understanding of co-adsorption reactions on Fh surface, the co-adsorption of phosphate and Zn(II) from aqueous solution to a synthesized Fh was determined. The batch experiments demonstrated a synergistic adsorption of phosphate and Zn(II) on Fh. In the pH range of 3.5-6, the adsorption of the two contaminants showed strong pH dependence in the single solute adsorption systems, but the dependence alleviated in the simultaneous adsorption system. X-ray photoelectron spectroscopy (XPS) revealed that the chemical shifts of Zn 2p1/2 and Zn 2p3/2 binding energies were more significant than that of P 2p in the single and simultaneous adsorption systems. On the other side, in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) observed increased formation of outer- and inner-sphere complexes of phosphate in the simultaneous system. Thus, the synergistic adsorption of the two contaminants could be attributed to the formation of ternary complexes as well as electrostatic interactions, while surface precipitation could not be completely ruled out. On the basis of the results from both the batch adsorption experiments and structural characterization, these two contaminants were likely to form phosphate-bridged ternary complexes (≡Fe-P-Zn) in the simultaneous adsorption system. PMID:26461439

  11. Adsorption of Iodine and Potassium on Bi2Sr2CaCu2O8+δ Investigated by Low Energy Alkali Ion Scattering

    SciTech Connect

    Gu, G.D.; Gann, R.D.; Cao, J.X.; Wu, R.Q.; Wen, J.; Xu, Z.; Gu, G.D.; Yarmoff, J.A.

    2010-01-01

    The adsorption of K and I on the surface of the high-T{sub c} cuprate BSCCO-2212 is investigated with low-energy (0.8 to 2 keV) Na{sup +} ion scattering and density functional theory (DFT). Samples were cleaved in ultrahigh vacuum and charge-resolved spectra of the scattered ions were collected with time-of-flight. The spectra contain a single peak representing Na scattered from Bi, as the clean surfaces are terminated by BiO. The neutralization of scattered Na depends on the local potential above the target site, and the angular dependence indicates that the clean surface has an inhomogeneous potential. Neutralization is dependent on the coverage of I, but independent of K adsorption. DFT suggests high-symmetry sites for the adsorption of both I and K, and that the potential above the Bi sites is altered by I by an amount consistent with the experimental findings, while the potential is not affected by K adsorption. DFT also enables an experimental determination of the 'freezing distance,' which is the effective point beyond which charge exchange does not occur, to be 1.6 {+-} 0.1 {angstrom} from the outermost Bi layer.

  12. Energy budget closure and field scale estimation of canopy energy storage with increased and sustained turbulence

    NASA Astrophysics Data System (ADS)

    Anderson, R. G.; Wang, D.

    2012-12-01

    Eddy Covariance (EC) is widely used for direct, non-invasive observations of land-atmosphere energy and mass fluxes. However, EC observations of available energy fluxes are usually less than fluxes inferred from radiometer and soil heat flux observations; thus introducing additional uncertainty in using and interpreting EC flux measurements. We compare EC observations from two towers established over sugarcane (Saccharum officinarum L.) in Hawai'i, USA under similar cultivation, temperature, sunlight, and precipitation, but drastically different wind conditions due to orographic effects. At a daily scale, we find that energy closure for both towers occurs on days when the entire 24 hours has sufficient turbulence. At our windier site, this turbulence condition occurs over 60% of the time, which contributes to substantially better daily energy closure (~98%) than at the calmer site (~75%). At our windy site, we then invert the daily energy closure for continuously windy days to calculate canopy energy storage. At full canopy, peak daily canopy energy storage fluxes (200-400 Wm-2) are approximately an order of magnitude larger than soil heat flux (20-40 Wm-2). As a fraction of net radiation, canopy energy storage appears to vary seasonally and shows substantially greater variability than soil heat flux. The results illustrate the importance of sustained turbulence for accurate, direct measurement of land-atmosphere fluxes. As increasing number of EC towers are established in complex terrain, these results indicate the need for preliminary wind studies to optimize tower placement where orography enhances, rather than suppresses, turbulence.

  13. The impact of the competitive adsorption of ions at surface sites on surface free energies and surface forces

    NASA Astrophysics Data System (ADS)

    Parsons, Drew F.; Salis, Andrea

    2015-04-01

    The relationship between surface charge and surface potential at the solid-liquid interface is often determined by a charge regulation process, the chemisorption of a potential determining ion such as H+. A subtle ion-specific effect can be observed when other ions compete with the primary potential determining ion to bind to a surface site. Site competition may involve alternative ions competing for a first binding site, e.g., metals ions competing with H+ to bind to a negatively charged oxide or carboxyl site. Second-binding sites with site competition may also be found, including amphoteric OH2+ sites, or anion binding to amine groups. In this work, a general theoretical model is developed to describe the competitive adsorption of ions at surface sites. Applied to the calculation of forces, the theory predicts a 20% increase in repulsion between titania surfaces in 1 mM NaCl, and a 25% reduction in repulsion between silica surfaces in 0.1M NaCl compared to calculations neglecting ion site competition.

  14. The impact of the competitive adsorption of ions at surface sites on surface free energies and surface forces.

    PubMed

    Parsons, Drew F; Salis, Andrea

    2015-04-01

    The relationship between surface charge and surface potential at the solid-liquid interface is often determined by a charge regulation process, the chemisorption of a potential determining ion such as H(+). A subtle ion-specific effect can be observed when other ions compete with the primary potential determining ion to bind to a surface site. Site competition may involve alternative ions competing for a first binding site, e.g., metals ions competing with H(+) to bind to a negatively charged oxide or carboxyl site. Second-binding sites with site competition may also be found, including amphoteric OH2 (+) sites, or anion binding to amine groups. In this work, a general theoretical model is developed to describe the competitive adsorption of ions at surface sites. Applied to the calculation of forces, the theory predicts a 20% increase in repulsion between titania surfaces in 1 mM NaCl, and a 25% reduction in repulsion between silica surfaces in 0.1M NaCl compared to calculations neglecting ion site competition. PMID:25854258

  15. Adsorption of pyridine onto the metal organic framework MIL-101.

    PubMed

    Kim, Mi Jin; Park, Se Min; Song, Sun-Jung; Won, Jiyeon; Lee, Jin Yong; Yoon, Minyoung; Kim, Kimoon; Seo, Gon

    2011-09-15

    The adsorption of pyridine onto the metal organic framework MIL-101 was investigated by experimental and theoretical methods. The amount of pyridine adsorbed on MIL-101 was extraordinarily large at 20 °C, corresponding to about 950 mg/g of dried MIL-101 and approximately half of the voids being filled. Most of the pyridine that had filled the voids was rapidly removed by evacuation at room temperature, but some of the pyridine was so strongly adsorbed that it was retained even under evacuation at 150 °C. Although IR spectra of the adsorbed pyridine indicated the adsorption of pyridine as pyridinium ions and coordinated pyridine at low temperatures, increasing the adsorption temperature induced partial cleavage of the pyridine rings. The high stabilization energy of pyridine on the coordinative unsaturated sites (CUS) of MIL-101, obtained by theoretical calculation, -103 kJ/mol, supported the strong adsorption of pyridine on the CUS. PMID:21700293

  16. Microbial desalination cell with capacitive adsorption for ion migration control.

    PubMed

    Forrestal, Casey; Xu, Pei; Jenkins, Peter E; Ren, Zhiyong

    2012-09-01

    A new microbial desalination cell with capacitive adsorption capability (cMDC) was developed to solve the ion migration problem facing current MDC systems. Traditional MDCs remove salts by transferring ions to the anode and cathode chambers, which may prohibit wastewater beneficial reuse due to increased salinity. The cMDC uses adsorptive activated carbon cloth (ACC) as the electrodes and utilizes the formed capacitive double layers for electrochemical ion adsorption. The cMDC removed an average of 69.4% of the salt from the desalination chamber through electrode adsorption during one batch cycle, and it did not add salts to the anode or cathode chamber. It was estimated that 61-82.2mg of total dissolved solids (TDS) was adsorbed to 1g of ACC electrode. The cMDC provides a new approach for salt management, organic removal, and energy production. Further studies will be conducted to optimize reactor configuration and achieve in situ electrode regeneration. PMID:22784594

  17. Increased Body Weight Reduces Voluntary Movement to Maintain Energy Expenditure of Rats Exposed to Increases in Gravity

    NASA Technical Reports Server (NTRS)

    Wade, C. E.; Moran, M. M.; Stein, T. P.; Sin, Sidney (Technical Monitor)

    2001-01-01

    With the increase in obesity related diseases there is heightened interest in mechanisms regulating body weight. To assess the influence of increases in body weight on energy expenditure and intake in rats we employed variable levels of gravity. Our approach afforded the means to measure interactions of energy expenditure and intake in response to increases in body weight (body mass x gravity level). We found a dose relationship between rapid elevation of body weight and reduction of voluntary movement, such that the energy requirements for activity are unchanged, and total energy expenditure and intake maintained. Reduction of movement appears to be a response to increased body weight, rather than a contributing factor, suggesting a new regulatory pathway.

  18. Energy of Tycho's Supernova Remnant is increasing with time

    PubMed Central

    Barenblatt, Grigory Isaakovich

    2008-01-01

    It is shown, using the Zeldovich integral relations, that the energy of Tycho's Supernova Remnant is strongly growing with time, approximately as t1/3. This growth can be attributed to the exothermic reactions going inside the remnant. The use of the assumption of the adiabaticity of the motion inside of the shock front, and no losses or gain of energy at the front, seems therefore unjustified. PMID:18202174

  19. Kinetics and Thermodynamics of Reserpine Adsorption onto Strong Acidic Cationic Exchange Fiber

    PubMed Central

    Guo, Zhanjing; Liu, Xiongmin; Huang, Hongmiao

    2015-01-01

    The kinetics and thermodynamics of the adsorption process of reserpine adsorbed onto the strong acidic cationic exchange fiber (SACEF) were studied by batch adsorption experiments. The adsorption capacity strongly depended on pH values, and the optimum reserpine adsorption onto the SACEF occurred at pH = 5 of reserpine solution. With the increase of temperature and initial concentration, the adsorption capacity increased. The equilibrium was attained within 20 mins. The adsorption process could be better described by the pseudo-second-order model and the Freundlich isotherm model. The calculated activation energy Ea was 4.35 kJ/mol. And the thermodynamic parameters were: 4.97<ΔH<7.44 kJ/mol, -15.29<ΔG<-11.87 kJ/mol and 41.97<ΔS<47.35 J/mol·K. The thermodynamic parameters demonstrated that the adsorption was an endothermic, spontaneous and feasible process of physisorption within the temperature range between 283 K and 323 K and the initial concentration range between 100 mg/L and 300 mg/L. All the results showed that the SACEF had a good adsorption performance for the adsorption of reserpine from alcoholic solution. PMID:26422265

  20. Experiments to Increase the Used Energy With the PEGASUS Railgun

    NASA Astrophysics Data System (ADS)

    Hundertmark, Stephan; Schneider, Markus; Simicic, Dejan; Vincent, Gregory

    2014-10-01

    The French-German Research Institute (ISL) has several railguns installed, the largest of these is the PEGASUS accelerator. It is a 6m long, 4x4 cm2 caliber distributed energy supply (DES) railgun. It has a 10 MJ capacitor bank as energy supply attached to it. In the past, this installation was used to accelerate projectiles with a mass of about 300 g to velocities up to 2500 m/s. In the ongoing investigation, it is attempted to accelerate heavier projectiles to velocities above 2000m/s. For this a new type of projectile including a payload section was developed. In this paper the results of the experiments with payload projectiles using a primary energy between 3.8 MJ and 4.8 MJ are discussed.

  1. Staging Laser Plasma Accelerators for Increased Beam Energy

    SciTech Connect

    Panasenko, D.; Shu, A. J.; Schroeder, C. B.; Gonsalves, A. J.; Nakamura, K.; Matlis, N. H.; Cormier-Michel, E.; Plateau, G.; Lin, C.; Toth, C.; Geddes, C. G. R.; Esarey, E.; Leemans, W. P.

    2009-01-22

    Staging laser plasma accelerators is an efficient way of mitigating laser pump depletion in laser driven accelerators and necessary for reaching high energies with compact laser systems. The concept of staging includes coupling of additional laser energy and transporting the electron beam from one accelerating module to another. Due to laser damage threshold constraints, in-coupling laser energy with conventional optics requires distances between the accelerating modules of the order of 10 m, resulting in decreased average accelerating gradient and complicated e-beam transport. In this paper we use basic scaling laws to show that the total length of future laser plasma accelerators will be determined by staging technology. We also propose using a liquid jet plasma mirror for in-coupling the laser beam and show that it has the potential to reduce distance between stages to the cm-scale.

  2. Staging laser plasma accelerators for increased beam energy

    SciTech Connect

    Panasenko, Dmitriy; Shu, Anthony; Schroeder, Carl; Gonsalves, Anthony; Nakamura, Kei; Matlis, Nicholas; Cormier-Michel, Estelle; Plateau, Guillaume; Lin, Chen; Toth, Csaba; Geddes, Cameron; Esarey, Eric; Leemans, Wim

    2008-09-29

    Staging laser plasma accelerators is an efficient way of mitigating laser pump depletion in laser driven accelerators and necessary for reaching high energies with compact laser systems. The concept of staging includes coupling of additional laser energy and transporting the electron beam from one accelerating module to another. Due to laser damage threshold constraints, in-coupling laser energy with conventional optics requires distances between the accelerating modules of the order of 10m, resulting in decreased average accelerating gradient and complicated e-beam transport. In this paper we use basic scaling laws to show that the total length of future laser plasma accelerators will be determined by staging technology. We also propose using a liquid jet plasma mirror for in-coupling the laser beam and show that it has the potential to reduce distance between stages to the cm-scale.

  3. Evaluation of the adsorption capacity of alkali-treated waste materials for the adsorption of sulphamethoxazole.

    PubMed

    Kurup, Lisha

    2012-01-01

    The present work is to develop potential adsorbents from waste material and employ them for the removal of a hazardous antibacterial, sulphamethoxazole, from the wastewater by the Adsorption technique. The Adsorption technique was used to impound the dangerous antibiotics from wastewater using Deoiled Soya (DOS), an agricultural waste, and Water Hyacinth (WH), a prolific colonizer. The adsorption capacity of these adsorbents was further enhanced by treating them with sodium hydroxide solution and it was seen that the adsorption capacity increases by 10 to 25%. Hence a comparative account of the adsorption studies of all the four adsorbents, i.e. DOS, Alkali-treated DOS, WH and Alkali-treated Water Hyacinth has been discussed in this paper. Different isotherms like Freundlich, Langmuir and Dubinin-Radushkevich were also deduced from the adsorption data. Isotherm studies were in turn used in estimating the thermodynamic parameters. DOS showed sorption capacity of 0.0007 mol g(-1) while Alkali-treated Deoiled Soya exhibited 0.0011 mol g(-1) of sorption capacity, which reveals that the adsorption is higher in case of alkali-treated adsorbent. The mean sorption energy (E) was obtained between 9 and 12 kJ mol, which shows that the reaction proceeds by ion exchange reaction. Kinetic study reveals that the reaction follows pseudo-second-order rate equation. Moreover, mass transfer studies performed for the ongoing processes show that the mass transfer coefficient obtained for alkali-treated moieties was higher than the parent moieties. The breakthrough curves plotted from the column studies show percentage saturation of 90-98%. About 87-97% of sulphamethoxazole was recovered from column by desorption. PMID:22508113

  4. Is increased Nuclear Energy a practical response to Global Warming?

    NASA Astrophysics Data System (ADS)

    Stevens, Jeanne

    2007-05-01

    With the threat of global warming there has been renewed interest in nuclear energy as a carbon-free energy source. There are currently 15 nuclear power plants planned for completion in the U.S. by 2014. In the last 30 years, however, investment and public support for nuclear energy has been minimal. Some factors that led to this loss of interest - high economic costs, risk of accident and radiation exposure, and the challenges of storing nuclear waste - have been analyzed in several recent publications. Comparing the costs and risks of nuclear energy to the benefits in reduced carbon emissions is the goal of this report. Coal plants contribute the most carbon dioxide of all types of power plants. The method of this study is a direct comparison of coal plants and nuclear plants in four areas: the current cost per kWh, the predicted annual cost for health issues, the statistically predicted deaths, and the clean-up costs assuming each facility is as ``green'' as possible. A normalized cost/risk value is then calculated for each plant type. Discussion for how these values are likely to vary is included. To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.NWS07.C1.11

  5. Window performance and building energy use: Some technical options for increasing energy efficiency

    NASA Astrophysics Data System (ADS)

    Selkowitz, Stephen

    1985-11-01

    Window system design and operation has a major impact on energy use in buildings as well as on occupants' thermal and visual comfort. Window performance will be a function of optical and thermal properties, window management strategies, climate and orientation, and building type and occupancy. In residences, heat loss control is a primary concern, followed by sun control in more southerly climates. In commercial buildings, the daylight provided by windows may be the major energy benefits but solar gain must be controlled so that increased cooling loads do not exceed daylighting savings. Reductions in peak electrical demand and HVAC system size may also be possible in well-designed daylighted buildings.

  6. Global versus local adsorption selectivity

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  7. Increasing beam power and energy with the SBS forward energy transfer instability

    NASA Astrophysics Data System (ADS)

    Kirkwood, R. K.; London, R. A.; Dunlop, W. H.; Michel, P. A.; Williams, E. A.; Fournier, K. B.; Landen, O. L.; MacGowan, B. J.

    2012-10-01

    The understanding of the exchange of forward going power and energy between two crossing beams in a plasma [1] is now sufficiently developed that it can be used to enable access to new experimental configurations. The existing models of the process allow the design of beam combiners that will produce higher energy in individual beams for new applications in ignition and HED physics. For example the Energy Partitioning and Energy Coupling (EPEC) [2] program is simulating nuclear events in various environments by delivering energy to the center of a chamber through a narrow tube that allows minimal perturbation of the surrounding region. We will describe the design of gas filled targets that will allow a 2x to 5x increase in the energy in a single NIF quad to enable higher yield events to be simulated in EPEC. These designs as well as advanced ignition target designs will require models with improved precision to predict their performance accurately. We will also compare the predictions of existing and emerging models of wave saturation [3] with the existing experimental data to determine the uncertainty in the models.[4pt] [1] P. Michel Physics of Plasmas 2010.[0pt] [2] K. Fournier, these proceedings[0pt] [3] P. Michel, E. Williams, these proceedings.

  8. Synthesis and adsorption performance of Mg(OH)2 hexagonal nanosheet-graphene oxide composites

    NASA Astrophysics Data System (ADS)

    Liu, Mengdi; Xu, Jing; Cheng, Bei; Ho, Wingkei; Yu, Jiaguo

    2015-03-01

    A series of Mg(OH)2 hexagonal nanosheet-graphene oxide (GO) composites were synthesized through a simple hydrothermal method using magnesium nitrate and GO as precursors, sodium nitrate and sodium oxalate as additives, and sodium hydroxide and ammonia as precipitants. The as-prepared samples were characterized by X-ray diffraction, nitrogen adsorption-desorption isotherms, Raman spectroscopy, zeta potential analysis, and scanning electron microscopy (SEM). The adsorption affinity of the as-prepared samples toward congo red (CR) in water was analyzed and investigated. Results indicated that GO addition influenced the thickness, morphology, and adsorption performance of Mg(OH)2 hexagonal nanosheets. As GO concentration increased, the thickness decreased. Especially at high GO concentration (1 wt%), Mg(OH)2 hexagonal nanosheets changed into aggregated flower-like spheres. Addition of small amounts of GO also increased the adsorption capacity of Mg(OH)2. The equilibrium adsorption data of CR on the composite were further investigated by Langmuir and Freundlich models, indicating that the Langmuir model was much more suitable for the experimental data. The sample prepared with 0.5 wt% GO showed the highest adsorption capacity with 118 mg g-1. The experimental data were then fitted using pseudo-second order kinetics, suggesting that pseudo-second order kinetics could well describe the adsorption of CR on composites. Adsorption thermodynamics analysis showed that the adsorption activation energy was 29.2 kJ mol-1, suggesting that the adsorption of CR onto the samples was physical adsorption. Adsorption between the samples and CR was mainly due to the strong electrostatic attraction between them because they had opposite charges. These findings indicated that Mg(OH)2-GO composite was an effective adsorbent for the removal of CR in water.

  9. Surface energy increase of oxygen-plasma-treated PET

    SciTech Connect

    Cioffi, M.O.H.; Voorwald, H.J.C.; Mota, R.P

    2003-03-15

    Prosthetic composite is a widely used biomaterial that satisfies the criteria for application as an organic implant without adverse reactions. Polyethylene therephthalate (PET) fiber-reinforced composites have been used because of the excellent cell adhesion, biodegradability and biocompatibility. The chemical inertness and low surface energy of PET in general are associated with inadequate bonds for polymer reinforcements. It is recognized that the high strength of composites, which results from the interaction between the constituents, is directly related to the interfacial condition or to the interphase. A radio frequency plasma reactor using oxygen was used to treat PET fibers for 5, 20, 30 and 100 s. The treatment conditions were 13.56 MHz, 50 W, 40 Pa and 3.33x10{sup -7} m{sup 3}/s. A Rame-Hart goniometer was used to measure the contact angle and surface energy variation of fibers treated for different times. The experimental results showed contact angle values from 47 deg. to 13 deg. and surface energies from 6.4x10{sup -6} to 8.3x10{sup -6} J for the range of 5 to 100 s, respectively. These results were confirmed by the average ultimate tensile strength of the PET fiber/ polymethylmethacrylate (PMMA) matrix composite tested in tensile mode and by scanning electron microscopy.

  10. Adsorption of Cadmium, Nickel and Zinc in a Brazilian Oxisoil

    NASA Astrophysics Data System (ADS)

    Casagrande, José Carlos; Martins, Susian Christian; Soares, Marcio Roberto

    2010-05-01

    The adsorption reactions mechanisms provide the understanding of the pollutant fate metals and often control the bioavailability and transport of heavy metals ions in soil, indicating the preventive environmental control. The cadmium, nickel and zinc behavior in the soils are explained by the reactions of adsorption, influenced by pH and ionic strength. The objective of this work was to study the influence of those factors on cadmium, nickel and zinc adsorption in an oxisol. It was studied the Cd, Ni and Zn adsorption in soil samples of the State of São Paulo (Anionic "Xanthic" Acrudox), collected in surface and in depth and submitted to solutions of Ca(NO3)2 1,0; 0,1 and 0,01 mol L-1. The pH of the samples from 3,0 to 10,0 was varied adding NaOH or HCl 4 mol L-1 not surpassing 2% of the electrolyte volume. The soil samples received 5,0 mg dm-3 of cadmium, nickel and zinc, ratio 1:10 (2,0 g of soil: 20 solution ml) and were shacked for 24 hours. The cadmium, nickel and zinc adsorption increased with pH, reaching it picks at pH 7,0 for cadmium and approximately at pH 6,0 for nickel and zinc. This indicates that zinc and nickel have higher affinity than cadmium with the soil colloids, because it reached the maximum adsorption in a small pH value. In other words, the amount of negative charges necessary to promote the maximum adsorption was small for zinc. The influence of ionic strengths was small for cadmium, nickel and zinc adsorption, being similar from pH 3,0 to 10,0, in surface soil layer and in depth, demonstrating that competition with Ca2+ for the retention colloid sites of the soils didn't interfere in the adsorption. In that way, it is supposed that cadmium, nickel and zinc binding energy is high in a soil rich in Fe and Al oxides. Adsorption of cadmium, nickel and zinc was similar for the ionic strengths, not depending on PZSE. The cadmium, nickel and zinc adsorption increased with pH elevation, with small ionic strength influence. Nickel and zinc have

  11. Insights into the effect of coverage on CO adsorption and dissociation over Rh(1 0 0) surface: A theoretical study

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaojun; Zhang, Riguang; Ling, Lixia; Wang, Baojun

    2014-11-01

    The adsorption, dissociation and desorption of CO at different coverage over Rh(1 0 0) surface have been systematically investigated using density functional theory method together with the periodic slab model. Our results show that at the coverage less than or equal to 4/12 ML, CO favored the most stable bridge site adsorption, and the adsorption energies of CO have little difference; while at the coverage greater than or equal to 5/12 ML, the lateral repulsive interaction begins to affect the adsorption structures and the corresponding adsorption energies of adsorbed CO molecules, and the interaction will be stronger with the increasing of CO coverage, which leads to CO migration over Rh(1 0 0) surface when CO coverage is greater than or equal to 10/12 ML. The adsorption energies of these CO molecules will decrease successively until the saturated adsorption with the CO coverage of 12/12 ML. Further calculations on CO dissociation indicate that when CO coverage is greater than or equal to 3/12 ML, the dissociation of adsorbed CO molecules will be unfavorable both kinetically and thermodynamically, suggesting that only molecule CO adsorption are favored. Considering the catalytic activity of Rh(1 0 0) surface toward CO dissociation and the higher CO coverage under the continuous supply of CO in syngas conversion, it is to be expected that only molecule CO adsorption exist on Rh catalyst.

  12. Development of facile property calculation model for adsorption chillers based on equilibrium adsorption cycle

    NASA Astrophysics Data System (ADS)

    Yano, Masato; Hirose, Kenji; Yoshikawa, Minoru; Thermal management technology Team

    Facile property calculation model for adsorption chillers was developed based on equilibrium adsorption cycles. Adsorption chillers are one of promising systems that can use heat energy efficiently because adsorption chillers can generate cooling energy using relatively low temperature heat energy. Properties of adsorption chillers are determined by heat source temperatures, adsorption/desorption properties of adsorbent, and kinetics such as heat transfer rate and adsorption/desorption rate etc. In our model, dependence of adsorption chiller properties on heat source temperatures was represented using approximated equilibrium adsorption cycles instead of solving conventional time-dependent differential equations for temperature changes. In addition to equilibrium cycle calculations, we calculated time constants for temperature changes as functions of heat source temperatures, which represent differences between equilibrium cycles and real cycles that stemmed from kinetic adsorption processes. We found that the present approximated equilibrium model could calculate properties of adsorption chillers (driving energies, cooling energies, and COP etc.) under various driving conditions quickly and accurately within average errors of 6% compared to experimental data.

  13. Effect of organic matter and calcium carbonate on behaviors of cadmium adsorption-desorption on/from purple paddy soils.

    PubMed

    Zhao, Xiulan; Jiang, Tao; Du, Bin

    2014-03-01

    Batch experiments and sequential extraction analysis were employed to investigate the effects of soil organic matter and CaCO3 on the adsorption and desorption of cadmium (Cd(2+)) onto and from two purple paddy soils, an acidic purple paddy soil (APPS) and a calcareous purple paddy soil (CPPS). The Cd(2+) adsorption isotherms on both soils could be well-described by the Langmuir and Freundlich equations. CPPS had a higher capacity and a stronger affinity for Cd(2+) adsorption compared with APPS. The adsorption process of Cd(2+) on APPS was dominated by electrostatic attractions, whereas the adsorption mechanism varied depending on the Cd(2+) concentrations in equilibrium solutions on CPPS. At low equilibrium concentrations, the adsorption process was primarily specific adsorption, but nonspecific adsorption dominated at high equilibrium concentrations. Removal of organic matter decreased the amount of Cd(2+) adsorption on both of the soils, slightly affected the Cd(2+) desorption rate and exchangeable Cd (EXC-Cd) in APPS and increased the desorption rate and EXC-Cd in CPPS, suggesting that the effect of organic matter on Cd(2+) adsorption-desorption depends on the soils. CPPS and APPS containing CaCO3 exhibited higher adsorption amounts but lower desorption rates and lower proportions of EXC-Cd than those of their corresponding soils without CaCO3, demonstrating that CaCO3 played an important role in Cd(2+) specific adsorption on soil. The changes in the thermodynamic parameters, including free energy (ΔG(0)), enthalpy (ΔH(0)) and entropy (ΔS(0)), as evaluated by the Van't Hoff equations, indicated that the adsorption was a spontaneous and endothermic process with the primary interaction forces of dipole interactions and hydrogen bonds on APPS, whereas both physical and chemical interactions dominated the adsorption on CPPS. PMID:24289979

  14. Method of local increments for the calculation of adsorption energies of atoms and small molecules on solid surfaces. 2. CO/MgO(001).

    PubMed

    Staemmler, Volker

    2011-06-30

    The method of local increments is used in connection with an embedded cluster approach and wave function based quantum chemical ab initio methods to describe the adsorption of a single CO molecule on the MgO(001) surface. The first step in this approach is a conventional Hartree-Fock calculation. The occupied orbitals are then localized by means of the Foster-Boys localization procedure, and the full system is decomposed into several "subunits" that consist of the orbitals localized at the CO molecule and at the Mg and O atoms of the MgO cluster. The correlation energy is expanded into a series of local n-body increments that are evaluated separately and independently. In this way, big savings in computer time can be achieved because (a) the treatment of a large system is replaced with a series of much faster calculations for small subsystems and (b) the big basis sets necessary for describing dispersion effects are only needed for the atoms in the respective subsystem while all other atoms can be treated by medium size Hartree-Fock type basis sets. The coupled electron pair approach, CEPA, an approximate coupled cluster method, is used to calculate the correlation energies of the various subsystems. For the vertical adsorption of CO on top a Mg atom of the MgO(001) surface with the C atom toward Mg, the individual one- and two-body increments are calculated as functions of the CO-MgO separation and a full potential energy curve is constructed from them. A very shallow minimum with an adsorption energy of 0.016 eV at a Mg-C distance of 3.04 Å is found at the Hartree-Fock level, while inclusion of correlation (dispersion) effects shortens the Mg-C distance to 2.59 Å and yields a much larger adsorption energy of 0.124 eV. This is in very good agreement with the best experimental value of 0.14 eV. The basis set superposition error, BSSE, was fully corrected for by the counterpoise method and the bonding mechanism was analyzed at the Hartree-Fock level by means of

  15. Adsorption of insecticidal Cry1Ab protein to humic substances. 1. Experimental approach and mechanistic aspects.

    PubMed

    Sander, Michael; Tomaszewski, Jeanne E; Madliger, Michael; Schwarzenbach, René P

    2012-09-18

    Adsorption is a key process affecting the fate of insecticidal Cry proteins (Bt toxins), produced by genetically modified Bt crops, in soils. However, the mechanisms of adsorption to soil organic matter (SOM) remain poorly understood. This work assesses the forces driving the adsorption of Cry1Ab to Leonardite humic acid (LHA), used as a model for SOM. We studied the effects of solution pH and ionic strength (I) on adsorption using a quartz crystal microbalance with dissipation monitoring and optical waveguide lightmode spectroscopy. Initial Cry1Ab adsorption rates were close to diffusion-limited and resulted in extensive adsorption, even at pH >6, at which LHA and Cry1Ab carry negative net charges. Adsorption increased with decreasing I at pH >6, indicating Cry1Ab-LHA patch-controlled electrostatic attraction via positively charged domains of Cry1Ab. Upon rinsing, only a fraction of Cry1Ab desorbed, suggesting a range of interaction energies of Cry1Ab with LHA. Different interaction energies likely resulted from nonuniformity in the LHA surface polarity, with higher Cry1Ab affinities to more apolar LHA regions due to the hydrophobic effect. Contributions from the hydrophobic effect were substantiated by comparison of the adsorption of Cry1Ab and the reference proteins albumin and lysozyme to LHA and to apolar and polar model surfaces. PMID:22862304

  16. 2, 4 dichlorophenol (2, 4-DCP) sorption from aqueous solution using granular activated carbon and polymeric adsorbents and studies on effect of temperature on activated carbon adsorption.

    PubMed

    Ghatbandhe, A S; Yenkie, M K N

    2008-04-01

    Adsorption equilibrium, kinetics and thermodynamics of 2,4-dichlorophenol (2,4-DCP), one of the most commonly used chlorophenol, onto bituminous coal based Filtrasorb-400 grade granular activated carbon, were studied in aqueous solution in a batch system with respect to temperature. Uptake capacity of activated carbon found to increase with temperature. Langmuir isotherm models were applied to experimental equilibrium data of 2, 4-DCP adsorption and competitive studies with respect to XAD resin were carried out. Equilibrium data fitted very well to the Langmuir equilibrium model. Adsorbent monolayer capacity 'Q0, Langmuir constant 'b' and adsorption rate constant 'k(a)' were evaluated at different temperatures for activated carbon adsorption. This data was then used to calculate the energy of activation of adsorption and also the thermodynamic parameters, namely the free energy of adsorption, deltaG0, enthalpy of adsorption, deltaH0 and the entropy of adsorption deltaS0. The obtained results showed that the monolayer capacity increases with the increase in temperatures. The obtained values of thermodynamic parameters showed that adsorption of 2,4 DCP is an endothermic process. Synthetic resin was not found efficient to adsorb 2,4 DCP compared to activated carbon. The order of adsorption efficiencies of three resins used in the study found as XAD7HP > XAD4 > XAD1180. PMID:19295102

  17. Gas adsorption on microporous carbon thin films

    SciTech Connect

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

    1992-05-01

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

  18. A fundamental study of the impact of pressure on the adsorption mechanism in reversed-phase liquid chromatography.

    PubMed

    Åsberg, Dennis; Samuelsson, Jörgen; Fornstedt, Torgny

    2016-07-29

    A fundamental investigation of the pressure effect on individual adsorption sites was undertaken based on adsorption energy distribution and adsorption isotherm measurements. For this purpose, we measured adsorption equilibrium data at pressures ranging from 100 to 1000bar at constant flow and over a wide concentration range for three low-molecular-weight solutes, antipyrine, sodium 2-naphthalenesulfonate, and benzyltriethylammonium chloride, on an Eternity C18 stationary phase. The adsorption energy distribution was bimodal for all solutes, remaining clearly so at all pressures. The bi-Langmuir model best described the adsorption in these systems and two types of adsorption sites were identified, one with a low and another with a high energy of interaction. Evidence exists that the low-energy interactions occur at the interface between the mobile and stationary phases and that the high-energy interactions occur nearer the silica surface, deeper in the C18 layer. The contribution of each type of adsorption site to the retention factor was calculated and the change in solute molar volume from the mobile to stationary phase during the adsorption process was estimated for each type of site. The change in solute molar volume was 2-4 times larger at the high-energy site, likely because of the greater loss of solute solvation layer when penetrating deeper into the C18 layer. The association equilibrium constant increased with increasing pressure while the saturation capacity of the low-energy site remained almost unchanged. The observed increase in saturation capacity for the high-energy site did not affect the column loading capacity, which was almost identical at 50- and 950-bar pressure drops over the column. PMID:27357740

  19. Detection of the adsorption of water monolayers through the ion oscillation frequency in the magnesium oxide lattice by means of low energy electron diffraction

    NASA Astrophysics Data System (ADS)

    Guevara-Bertsch, M.; Ramírez-Hidalgo, G.; Chavarría-Sibaja, A.; Avendaño, E.; Araya-Pochet, J. A.; Herrera-Sancho, O. A.

    2016-03-01

    We investigate the variation of the oscillation frequency of the Mg2+ and O2- ions in the magnesium oxide lattice due to the interactions of the surface with water monolayers by means of Low Energy Electron Diffraction. Our key result is a new technique to determine the adsorbate vibrations produced by the water monolayers on the surface lattice as a consequence of their change in the surface Debye temperature and its chemical shift. The latter was systematically investigated for different annealing times and for a constant external thermal perturbation in the range of 110-300 K in order to accomplish adsorption or desorption of water monolayers in the surface lattice.

  20. Studies on the adsorption of sulfo-group-containing aromatics by chitosan-β-cyclodextrin.

    PubMed

    Shi, Wenjian; Chen, Shuwei; Chang, Fei; Han, Yue; Zhang, Yuanzhang

    2012-01-01

    Chitosan-β-cyclodextrin (CTS-CD) prepared through a crosslinking reaction between chitosan and β-cyclodextrin was employed to adsorb the three following sulfo-group-containing aromatics: disodium 2-naphthol-3,6-disulfonate (R salt), 2-naphthalene sulfonic acid (NSA), and sodium dodecylbenzene sulfonate (SDBS). At 318 K, the saturated adsorption capacity of CTS-CD for R salt, NSA, and SDBS was 431, 416, and 376 mg/g, respectively. The experimental data fitted the second-order model well and the rate constant of the adsorption increased with the temperature increment. The values of apparent activation energy for R salt, NSA, and SDBS were calculated as 33.2, 34.2, and 16.8 kJ/mol respectively. The isothermal adsorption was found following the Langmuir adsorption equation. The negative values of ΔG and the positive values of ΔH indicated that the adsorption process was spontaneous and exothermic. PMID:22339013

  1. Systematic DFT-GGA study of hydrogen adsorption on transition metals

    NASA Astrophysics Data System (ADS)

    Vasić, D.; Ristanović, Z.; Pašti, I.; Mentus, S.

    2011-12-01

    Computational study of hydrogen adsorption on (111) surface of transition metals with face centered cubic (fcc) lattice is reported and the results are compared with available experimental and theoretical data. In addition, dissociative adsorption of hydrogen on Pt(111), Pt(100) and Pt(110) is studied in the range of coverage from 0.25 to 1 monolayer. In the case of Pt(111) preferential adsorption site was found to be three-coordinated fcc-hollow site, while on Pt(100) and Pt(110) surface hydrogen settles on two-coordinated bridge and short bridge site, respectively. Hydrogen adsorption energy was found to decrease with the increasing coverage. Structural changes of studied Pt surfaces upon hydrogen adsorption have been compared with the experimental data existing in the literature and good qualitative agreement has been obtained.

  2. Synergistic behaviour of ionic liquid impregnated sulphate-crosslinked chitosan towards adsorption of Cr(VI).

    PubMed

    Shekhawat, A; Kahu, S; Saravanan, D; Jugade, R

    2015-09-01

    Aliquat-336 (an ionic liquid) impregnated sulphate-crosslinked chitosan (SCC) was prepared for escalating the adsorption of hexavalent chromium through concurrent interaction. The compound obtained was intensively characterized using Fourier transform infra red (FT-IR), X-ray diffraction (XRD), Scanning electron microscopic (SEM) and Energy dispersive X-ray (EDX) studies. Various isotherm studies have been carried out to understand the adsorption mechanism. Quantitative adsorption of Cr(VI) was observed at pH 3.0 with adsorption capacity of 250.90 mg g(-1) in accordance with Langmuir isotherm. The adsorption of Cr(VI) followed pseudo-second-order kinetics. The adsorption efficiency was found to decrease with increase in temperature due to increased randomness at interaction sites. The adsorption process was found to be exothermic and spontaneous in nature. Column studies were carried out to understand the applicability of the material for higher sample volumes. The adsorbent could be regenerated using sodium hydroxide treatment and the regenerated adsorbent had same efficiency towards adsorption of Cr(VI) as that of the original. PMID:26206740

  3. Protein adsorption onto medical alloys: Voltage effects

    NASA Astrophysics Data System (ADS)

    Gettens, Robert T. T.

    This work examined the adsorption of an important-plasma protein, fibrinogen (Fb), onto a clinically-relevant-biomedical alloy, 316L stainless steel (SS) and electrically polarized 316L SS. Then, several key-interfacial properties important to protein adsorption were examined. The overriding role of electrochemical (EC) charge-transfer processes in the behavior of both the adsorption of Fb and interfacial properties was apparent. Adsorption of Fb onto polarized 316L SS was observed and quantified using both in situ and ex situ atomic force microscopy (AFM) techniques. Significant differences in Fb adsorption were observed across potential. Ex situ studies showed significantly lower area coverage and height of adsorbed Fb at cathodic potentials. In situ studies showed significantly slower kinetics below -100 mV. Current density data showed large charge-transfer processes (˜1x10 -5 to 1x10-4 A/cm2) taking place at voltages below -100 mV. A parallel-plate electrocapillary method was used to measure changes in metal-electrolyte surface energy (Deltagammasl) with potential. The results showed increasingly negative Deltagamma sl values on 316L SS at more cathodic voltages (i.e., more hydrophilic) and little to no change above -100 mV. These data correlate linearly with current density. Force measurements using a colloidal-AFM probe measured interfacial forces. Increasingly repulsive forces scaled with increasingly cathodic potentials; little interaction was detected at anodic potentials. These data correlated linearly with current density. The EC impedance was also studied. Electrochemical AFM (ECAFM) simultaneously gave impedance and structural changes with potential. Several regions of oxide topography/impedance characteristic were apparent which matched closely with the impedance behavior of the system. Through Mott-Schottky analysis the presence of the flatband potential was determined to be around -150 mV. Property observations of polarized 316L SS, specifically

  4. High-Resolution Electron Energy Loss Studies of Oxygen, Hydrogen, Nitrogen, Nitric Oxide, and Nitrous Oxide Adsorption on Germanium Surfaces.

    NASA Astrophysics Data System (ADS)

    Entringer, Anthony G.

    The first high resolution electron energy loss spectroscopy (HREELS) studies of the oxidation and nitridation of germanium surfaces are reported. Both single crystal Ge(111) and disordered surfaces were studied. Surfaces were exposed to H, O_2, NO, N _2O, and N, after cleaning in ultra-high vacuum. The Ge surfaces were found to be non-reactive to molecular hydrogen (H_2) at room temperature. Exposure to atomic hydrogen (H) resulted hydrogen adsorption as demonstrated by the presence of Ge-H vibrational modes. The HREEL spectrum of the native oxide of Ge characteristic of nu -GeO_2 was obtained by heating the oxide to 200^circC. Three peaks were observed at 33, 62, and 106 meV for molecular oxygen (O_2) adsorbed on clean Ge(111) at room temperature. These peaks are indicative of dissociative bonding and a dominant Ge-O-Ge bridge structure. Subsequent hydrogen exposure resulted in a shift of the Ge-H stretch from its isolated value of 247 meV to 267 meV, indicative of a dominant +3 oxidation state. A high density of dangling bonds and defects and deeper oxygen penetration at the amorphous Ge surface result in a dilute bridge structure with a predominant +1 oxidation state for similar exposures. Molecules of N_2O decompose at the surfaces to desorbed N_2 molecules and chemisorbed oxygen atoms. In contrast, both oxygen and nitrogen are detected at the surfaces following exposure to NO molecules. Both NO and N_2O appear to dissociate and bond at the top surface layer. Molecular nitrogen (N_2) does not react with the Ge surfaces, however, a precursor Ge nitride is observed at room temperature following exposure to nitrogen atoms and ions. Removal of oxygen by heating of the NO-exposed surface to 550^circC enabled the identification of the Ge-N vibrational modes. These modes show a structure similar to that of germanium nitride. This spectrum is also identical to that of the N-exposed surface heated to 550^circC. Surface phonon modes of the narrow-gap semiconducting

  5. Water and Carbon Dioxide Adsorption at Olivine Surfaces

    SciTech Connect

    Kerisit, Sebastien N.; Bylaska, Eric J.; Felmy, Andrew R.

    2013-11-14

    Plane-wave density functional theory (DFT) calculations were performed to simulate water and carbon dioxide adsorption at the (010) surface of five olivine minerals, namely, forsterite (Mg2SiO4), calcio-olivine (Ca2SiO4), tephroite (Mn2SiO4), fayalite (Fe2SiO4), and Co-olivine (Co2SiO4). Adsorption energies per water molecule obtained from energy minimizations varied from -78 kJ mol-1 for fayalite to -128 kJ mol-1 for calcio-olivine at sub-monolayer coverage and became less exothermic as coverage increased. In contrast, carbon dioxide adsorption energies at sub-monolayer coverage ranged from -20 kJ mol-1 for fayalite to -59 kJ mol-1 for calcio-olivine. Therefore, the DFT calculations show a strong driving force for carbon dioxide displacement by water at the surface of all olivine minerals in a competitive adsorption scenario. Additionally, adsorption energies for both water and carbon dioxide were found to be more exothermic for the alkaline-earth (AE) olivines than for the transition-metal (TM) olivines and to not correlate with the solvation enthalpies of the corresponding divalent cations. However, a correlation was obtained with the charge of the surface divalent cation indicating that the more ionic character of the AE cations in the olivine structure relative to the TM cations leads to greater interactions with adsorbed water and carbon dioxide molecules at the surface and thus more exothermic adsorption energies for the AE olivines. For calcio-olivine, which exhibits the highest divalent cation charge of the five olivines, ab initio molecular dynamics simulations showed that this effect leads both water and carbon dioxide to react with the surface and form hydroxyl groups and a carbonate-like species, respectively.

  6. Phosphate adsorption on lanthanum loaded biochar.

    PubMed

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

    2016-05-01

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

  7. Adsorption of polymeric brushes: Bridging

    NASA Astrophysics Data System (ADS)

    Johner, Albert; Joanny, Jean-François

    1992-04-01

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

  8. Increasing sp3 hybridized carbon atoms in germanium carbide films by increasing the argon ion energy and germanium content

    NASA Astrophysics Data System (ADS)

    Hu, C. Q.; Zheng, B.; Zhu, J. Q.; Han, J. C.; Zheng, W. T.; Guo, L. F.

    2010-04-01

    We have prepared germanium carbide (Ge1-xCx) films on Si(0 0 1) by radio frequency (RF) reactive sputtering a pure Ge(1 1 1) target in a CH4/Ar mixture discharge, and found that the sp3 hybridized carbon atoms in the Ge1-xCx film can be significantly increased in two ways. One is by increasing the Ge content via increasing the RF power during the film deposition, which can lead to a transition from sp2 C-C to sp3 C-Ge bonding in the film. Another is by increasing the Ar ion energy in a discharge Ar/CH4 gas by applying the negative bias voltage, which plays an important role in inducing the compressive stress in film. We find that when the compressive stress increases above a critical value of 2.2 GPa, an abrupt transition from sp2 C-C to sp3 C-C bonding occurs in the Ge1-xCx film, which is a consequence of energy minimization.

  9. Porous radiant burners having increased radiant output

    SciTech Connect

    Tong, Timothy W.; Sathe, Sanjeev B.; Peck, Robert E.

    1990-01-01

    Means and methods for enhancing the output of radiant energy from a porous radiant burner by minimizing the scattering and increasing the adsorption, and thus emission of such energy by the use of randomly dispersed ceramic fibers of sub-micron diameter in the fabrication of ceramic fiber matrix burners and for use therein.

  10. Theoretical study of heavy metal Cd, Cu, Hg, and Ni(II) adsorption on the kaolinite(0 0 1) surface

    NASA Astrophysics Data System (ADS)

    Zhao, Jian; He, Man-Chao

    2014-10-01

    Heavy metal pollution is currently of great concern because it has been recognized as a potential threat to air, water, and soil. Adsorption was one of the most popular methods for the removal of heavy metal. The adsorption of heavy metal Cd, Cu, Hg, and Ni(II) atoms on the hydroxylated (0 0 1) surface of kaolinite was investigated using density-functional theory within the generalized gradient approximation and a supercell approach. The coverage dependence of the adsorption structures and energetics were systematically studied for a wide range of coverage Θ [from 0.11 to 1.0 monolayers (ML)] and adsorption sites. The most stable among all possible adsorption sites for Cd(II) atom was the two-fold bridge site followed by the one-fold top site, and the top site was the most favorite adsorption site for Cu and Ni(II) atoms, while the three-fold hollow site was the most stable adsorption site for Hg(II) atom followed by the two-fold bridge site. The adsorption energy increases with the coverage for Cd, Cu, and Hg(II) atoms, thus indicating the higher stability of surface adsorption and a tendency to the formation of adsorbate islands (clusters) with increasing the coverage. However, the adsorption energy of Ni(II) atoms decreases when increasing the coverage. The adsorption capabilities of the kaolinite clay for the heavy metal atoms were in the order of Ni > Cu > Cd > Hg(II). The other properties of the Cd, Cu, Hg, and Ni(II)/kaolinite(0 0 1) system including the different charge distribution, the lattice relaxation, and the electronic density of states were also studied and discussed in detail.

  11. On the role of long range interactions for the adsorption of sexithiophene on Ag(110) surface

    SciTech Connect

    Matos, Jeronimo; Rojas, Tomas; Yildirim, Handan E-mail: Abdelkader.Kara@ucf.edu; Kara, Abdelkader E-mail: Abdelkader.Kara@ucf.edu

    2014-04-14

    The adsorption characteristics of the sexithiophene (6T) molecule on Ag(110) are studied using density functional theory with the inclusion of van der Waals (vdW) interactions. The stable adsorption configurations on 6T on Ag(110) as well as the nature of bonding the Ag substrate are evaluated. We also assess the performance of the vdW-DF method in describing the adsorption, energetics, heights, as well as the interface characteristics with the Ag(110) surface. We find two lowest adsorption energy configurations, at which the 6T molecule aligns with its molecular long axis parallel and perpendicular to the [001] direction, to be energetically close to each other, suggesting that they may coexist. Our findings indicate a significant increase in the 6T adsorption energies upon the inclusion of vdW interactions with the highest increase obtained using the opt-type functionals, in particular with the optB86b-vdW functional. The revPBE-vdW and rPW86-vdW2 functionals lead to less enhancement in adsorption energies that is attributed to the strong repulsive nature of these functionals, in agreement with earlier predictions. Upon adsorption of the 6T molecule, the changes in the atomic and electronic structures of the 6T molecule and Ag surface are found to be negligible; there is no charge transfer, and no interface state is observed. The work function is reduced upon adsorption with the largest change is ∼0.6 eV obtained using the optB88-vdW functional. The results are in good agreement with the available experimental observations of the adsorption configurations and the work function changes. Based on our results, we conclude that the nature of bonding for 6T on Ag(110) can be classified as strong physisorption.

  12. Phosphate adsorption performance of a novel filter substrate made from drinking water treatment residuals.

    PubMed

    Wang, Wendong; Ma, Cui; Zhang, Yinting; Yang, Shengjiong; Shao, Yue; Wang, Xiaochang

    2016-07-01

    Phosphate is one of the most predominant pollutants in natural waters. Laboratory experiments were conducted to investigate the phosphate adsorption performance of a (NFS) made from drinking water treatment residuals. The adsorption of phosphate on the NFS fitted well with the Freundlich isotherm and pseudo second-order kinetic models. At pH7.0, the maximum adsorption capacity of 1.03mg/g was achieved at 15°C corresponding to the wastewater temperature in cold months, and increased notably to 1.31mg/g at 35°C. Under both acidic conditions (part of the adsorption sites was consumed) and basic conditions (negative charges formed on the surface of NFS, which led to a static repulsion of PO4(3-) and HPO4(2-)), the adsorption of phosphate was slightly inhibited. Further study showed that part of the adsorption sites could be recovered by 0.25mol/L NaOH. The activation energy was calculated to be above 8.0kJ/mol, indicating that the adsorption of phosphate on NFS was probably a chemical process. Considering the strong phosphate adsorption capacity and recoverability, NFS showed great promise on enhancing phosphate removal from the secondary treated wastewater in the filtration process. PMID:27372133

  13. Effect of single silica gel particle adsorption on the transport processes in a humid air stream

    NASA Astrophysics Data System (ADS)

    Sanyal, Apratim; Basu, Saptarshi; Kumar, Pramod

    2013-11-01

    The effect of adsorption due to a single silica gel particle on a convective field consisting of humid air has been investigated numerically. The adsorption is incorporated as a sink term in the transport equation for species (water vapor) and has been modeled using Linear Driving Force model, while the heat released due to adsorption is taken as source term in the energy equation and proportional to the amount of water vapor adsorbed. The heat released creates a coupling between the species and the temperature field as the adsorption characteristics are directly influenced by particle temperature. The extent of species and temperature boundary layer show the diffusion of the adsorption effects into the free stream. Surface adsorption is found to decrease with Reynolds no. The particle surface temperature increases from forward stagnation point till downstream. This work provides a model for understanding the adsorption kinetics in convective stream for other adsorbate-adsorbent pair. Further more complex scenarios can be modeled such as presence of multiple adsorbent particles, the interaction of species and temperature boundary layers setup due to individual particles and their influence on the overall adsorption characteristics.

  14. Oxidative coupling and the irreversible adsorption of phenol by graphite.

    PubMed

    de Oliveira Pimenta, Aluisio Cesar; Kilduff, James E

    2006-01-15

    Uptake of phenol by graphite, and regeneration by methanol extraction, was measured to evaluate irreversible adsorption of phenols to carbon surfaces. The emphasis of this work was to identify the role of oxidative coupling, which has been invoked to explain irreversible phenol sorption by activated carbons. Graphite was chosen as a model carbon surface to eliminate potentially confounding effects of microporosity present in other types of carbonaceous sorbents. The isotherm data were well described by the Langmuir-Freundlich isotherm from pH 3 to 9. At pH 12, measured uptakes were higher than expected based on model predictions, suggesting the occurrence of an adsorption mechanism besides physisorption. One oxidative coupling product, 2,2'-dihydroxybiphenyl, was obtained exclusively after adsorption at pH values above 7, and appeared both in aqueous solution and in the methanol regenerant solution. The fraction of total uptake that was not recoverable by methanol extraction decreased with increasing phenol concentration in solution, suggesting preferential sorption by high-energy sites. However, absolute irreversible adsorption increased with phenol concentration in solution. Both fractional irreversible adsorption and 2,2'-dihydroxybiphenyl oxidative coupling product recovery as a function of pH and contact time demonstrated that irreversible sorption of phenol by graphite could not be explained by an oxidative coupling mechanism alone. PMID:16054157

  15. Increased physical activity has a greater effect than reduced energy intake on lifestyle modification-induced increases in testosterone.

    PubMed

    Kumagai, Hiroshi; Zempo-Miyaki, Asako; Yoshikawa, Toru; Tsujimoto, Takehiko; Tanaka, Kiyoji; Maeda, Seiji

    2016-01-01

    Obesity has reached epidemic proportions worldwide. Obesity results in reduced serum testosterone levels, which causes many disorders in men. Lifestyle modifications (increased physical activity and calorie restriction) can increase serum testosterone levels. However, it is unknown whether increased physical activity or calorie restriction during lifestyle modifications has a greater effects on serum testosterone levels. Forty-one overweight and obese men completed a 12-week lifestyle modification program (aerobic exercise training and calorie restriction). We measured serum testosterone levels, the number of steps, and the total energy intake. We divided participants into two groups based on the median change in the number of steps (high or low physical activities) or that in calorie restriction (high or low calorie restrictions). After the program, serum testosterone levels were significantly increased. Serum testosterone levels in the high physical activity group were significantly higher than those in the low activity group. This effect was not observed between the groups based on calorie restriction levels. We found a significant positive correlation between the changes in serum testosterone levels and the number of steps. Our results suggested that an increase in physical activity greatly affected the increased serum testosterone levels in overweight and obese men during lifestyle modification. PMID:26798202

  16. Adsorption of Rh(III) complexes from chloride solutions obtained by leaching chlorinated spent automotive catalysts on ion-exchange resin Diaion WA21J.

    PubMed

    Shen, Shaobo; Pan, Tonglin; Liu, Xinqiang; Yuan, Lei; Wang, Jinchao; Zhang, Yongjian; Guo, Zhanchen

    2010-07-15

    It was found that Rh, Pd and Pt contained in the spent ceramic automotive catalysts could be effectively extracted by dry chlorination with chlorine. In order to concentrate Rh(III) ions contained in the chloride solutions obtained, thermodynamic and kinetics studies for adsorption of Rh(III) complexes from the chloride solutions on an anionic exchange resin Diaion WA21J were carried out. Rh, Pd, Pt, Al, Fe, Si, Zn and Pb from the chloride solution could be adsorbed on the resin. The distribution coefficients (K(d)) of Rh(III) decreased with the increase in initial Rh(III) concentration or in adsorption temperature. The isothermal adsorption of Rh(III) was found to fit Langmuir, Freundlich and Dubinin-Kaganer-Radushkevich models under the adsorption conditions. The maximum monolayer adsorption capacities Q(max) based on Langmuir adsorption isotherms were 6.39, 6.61 and 5.81 mg/g for temperatures 18, 28 and 40 degrees C, respectively. The apparent adsorption energy of Rh was about -7.6 kJ/mol and thus Rh(III) adsorption was a physical type. The experimental data obtained could be better simulated by pseudo-first-order kinetic model and the activation energy obtained was 6.54 J/mol. The adsorption rate of Rh(III) was controlled by intraparticle diffusion in most of time of adsorption process. PMID:20346581

  17. 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.

  18. An accurate full-dimensional potential energy surface for H-Au(111): Importance of nonadiabatic electronic excitation in energy transfer and adsorption.

    PubMed

    Janke, Svenja M; Auerbach, Daniel J; Wodtke, Alec M; Kandratsenka, Alexander

    2015-09-28

    We have constructed a potential energy surface (PES) for H-atoms interacting with fcc Au(111) based on fitting the analytic form of the energy from Effective Medium Theory (EMT) to ab initio energy values calculated with density functional theory. The fit used input from configurations of the H-Au system with Au atoms at their lattice positions as well as configurations with the Au atoms displaced from their lattice positions. It reproduces the energy, in full dimension, not only for the configurations used as input but also for a large number of additional configurations derived from ab initio molecular dynamics (AIMD) trajectories at finite temperature. Adiabatic molecular dynamics simulations on this PES reproduce the energy loss behavior of AIMD. EMT also provides expressions for the embedding electron density, which enabled us to develop a self-consistent approach to simulate nonadiabatic electron-hole pair excitation and their effect on the motion of the incident H-atoms. For H atoms with an energy of 2.7 eV colliding with Au, electron-hole pair excitation is by far the most important energy loss pathway, giving an average energy loss ≈3 times that of the adiabatic case. This increased energy loss enhances the probability of the H-atom remaining on or in the Au slab by a factor of 2. The most likely outcome for H-atoms that are not scattered also depends prodigiously on the energy transfer mechanism; for the nonadiabatic case, more than 50% of the H-atoms which do not scatter are adsorbed on the surface, while for the adiabatic case more than 50% pass entirely through the 4 layer simulation slab. PMID:26429033

  19. An accurate full-dimensional potential energy surface for H–Au(111): Importance of nonadiabatic electronic excitation in energy transfer and adsorption

    SciTech Connect

    Janke, Svenja M.; Auerbach, Daniel J.; Kandratsenka, Alexander; Wodtke, Alec M.

    2015-09-28

    We have constructed a potential energy surface (PES) for H-atoms interacting with fcc Au(111) based on fitting the analytic form of the energy from Effective Medium Theory (EMT) to ab initio energy values calculated with density functional theory. The fit used input from configurations of the H–Au system with Au atoms at their lattice positions as well as configurations with the Au atoms displaced from their lattice positions. It reproduces the energy, in full dimension, not only for the configurations used as input but also for a large number of additional configurations derived from ab initio molecular dynamics (AIMD) trajectories at finite temperature. Adiabatic molecular dynamics simulations on this PES reproduce the energy loss behavior of AIMD. EMT also provides expressions for the embedding electron density, which enabled us to develop a self-consistent approach to simulate nonadiabatic electron-hole pair excitation and their effect on the motion of the incident H-atoms. For H atoms with an energy of 2.7 eV colliding with Au, electron-hole pair excitation is by far the most important energy loss pathway, giving an average energy loss ≈3 times that of the adiabatic case. This increased energy loss enhances the probability of the H-atom remaining on or in the Au slab by a factor of 2. The most likely outcome for H-atoms that are not scattered also depends prodigiously on the energy transfer mechanism; for the nonadiabatic case, more than 50% of the H-atoms which do not scatter are adsorbed on the surface, while for the adiabatic case more than 50% pass entirely through the 4 layer simulation slab.

  20. 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.

  1. π adsorption of ethene on to the {111} surface of copper. A periodic ab initio study of the effect of k-point sampling on the energy, atomic and electronic structure

    NASA Astrophysics Data System (ADS)

    Watson, G. W.; Wells, R. P. K.; Willock, D. J.; Hutchings, G. J.

    2000-07-01

    The adsorption of ethene on the {111} surface of copper has been studied by using density functional theory calculations with gradient corrections. The surface is described by a periodic (3×3) slab, three layers thick, with ethene adsorbed on one side. The energy of the adsorption shows great sensitivity to the k-point sampling employed, with single k-point calculations overestimating the binding by over 800% when compared with a calculation converged with respect to the k-point sampling. In addition, the structure of the adsorbed molecule is considerably distorted, which is in contradiction with conclusions drawn from the experimental vibrational frequencies. Calculations that are converged with respect to the k-point sampling indicate a much weaker interaction between the molecule and the surface, with adsorption energies of 11.1 and 10.9 kJ mol -1 for atop-h and atop-b, respectively. This weaker interaction leads to a geometry for the adsorbed molecule that is close to the gas-phase ethene structure, in agreement with the vibrational frequencies. We have proposed a model of molecular adsorption that is a balance between attraction, resulting from localised bond formation, and repulsion, due to interaction between the extended electronic states and the molecule's electron density. If the extended electronic states are underestimated, as in cluster or low k-point calculations, the repulsion is underestimated. This results in stronger bonding to the surface and overestimation of the adsorption energy.

  2. 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...

  3. Exploring the interfacial structure of protein adsorbates and the kinetics of protein adsorption: an in situ high-energy X-ray reflectivity study.

    PubMed

    Evers, Florian; Shokuie, Kaveh; Paulus, Michael; Sternemann, Christian; Czeslik, Claus; Tolan, Metin

    2008-09-16

    The high energy X-ray reflectivity technique has been applied to study the interfacial structure of protein adsorbates and protein adsorption kinetics in situ. For this purpose, the adsorption of lysozyme at the hydrophilic silica-water interface has been chosen as a model system. The structure of adsorbed lysozyme layers was probed for various aqueous solution conditions. The effect of solution pH and lysozyme concentration on the interfacial structure was measured. Monolayer formation was observed for all cases except for the highest concentration. The adsorbed protein layers consist of adsorbed lysozyme molecules with side-on or end-on orientation. By means of time-dependent X-ray reflectivity scans, the time-evolution of adsorbed proteins was monitored as well. The results of this study demonstrate the capabilities of in situ X-ray reflectivity experiments on protein adsorbates. The great advantages of this method are the broad wave vector range available and the high time resolution. PMID:18715021

  4. Adsorption of oxazole and isoxazole on BNNT surface: A DFT study

    NASA Astrophysics Data System (ADS)

    Kaur, Jasleen; Singla, Preeti; Goel, Neetu

    2015-02-01

    The adsorption behavior of oxazole and isoxazole heterocycles over the (6,0) zigzag and (5,5) armchair boron nitride nanotube (BNNT) has been studied within the formalism of density functional theory (DFT). The adsorption energies, the frontier molecular orbital (FMO) analysis and the structural changes at the adsorption site are indicative of covalent adsorption on the zigzag BNNT surface, while the adsorption is physical in nature on the armchair BNNT surface. The role of solvent in improving the adsorption properties over the BNNT surface is elucidated by reoptimizing the structures in aqueous phase. The solvation energy is indicative of remarkable increase in the solubility of BNNTs after adsorption of heterocyclic rings. The Density of states (DOS) Plots, natural bond orbital (NBO) analysis and the quantum molecular descriptors (QMD) are witness to the substantial changes in the electronic properties of the BNNT systems following the attachment of these heterocycles with the tube surface. The study envisages the functionalization of the BNNT as well as its applicability as carrier of the drugs containing heterocyclic rings oxazole and isoxazole with marked sensitivity to the type of adsorbate and the adsorbent.

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

    PubMed

    Hsieh; Teng

    2000-10-01

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

  6. Adsorption characteristics of diclofenac and sulfamethoxazole to graphene oxide in aqueous solution.

    PubMed

    Nam, Seung-Woo; Jung, Chanil; Li, Hang; Yu, Miao; Flora, Joseph R V; Boateng, Linkel K; Her, Namguk; Zoh, Kyung-Duk; Yoon, Yeomin

    2015-10-01

    The adsorptive properties of graphene oxide (GO) were characterized, and the binding energies of diclofenac (DCF) and sulfamethoxazole (SMX) on GO adsorption were predicted using molecular modeling. The adsorption behaviors of DCF and SMX were investigated in terms of GO dosage, contact time, and pH. Additionally, the effects of sonication on GO adsorption were examined. GO adsorption involves "oxygen-containing functional groups" (OCFGs) such as COOH, which exhibit negative charges over a wide range of pH values (pH 3-11). DCF (-18.8 kcal mol(-1)) had a more favorable binding energy on the GO surface than SMX (-15.9 kcal mol(-1)). Both DCF and SMX were removed from solution (adsorbed to GO), up to 35% and 12%, respectively, within 6h, and an increase in GO dosage enhanced the removal of DCF. Electrostatic repulsion occurred between dissociated DCF/SMX and the more negatively charged GO at basic pH (>pKa). The sonication of GO significantly improved the removal of DCF (75%) and SMX (30%) due to dispersion of exfoliated GO particles and the reduction of OCFGs on the GO surface. Both DCF and SMX in the adsorption isotherm were explained well by the Freundlich model. The results of this study can be used to maximize the adsorption capacities of micropollutants using GO in water treatment processes. PMID:25911329

  7. Adsorption of nonmetallic elements on defect-free MgO(001) surface - DFT study

    NASA Astrophysics Data System (ADS)

    Pašti, Igor A.; Baljozović, Miloš; Skorodumova, Natalia V.

    2015-02-01

    Adsorption of 11 non-metals (H, B, C, N, O, F, Si, P, S, Cl and Br) on defect-free MgO(001) surface was investigate using DFT approach. Adsorption energies were found to be between - 0.56 eV (hydrogen adsorption) and - 2.63 eV (carbon adsorption). Charge transfer from substrate to adsorbate was observed to follow the periodicity in the Periodic Table of Elements, as increases from left to right and decreases from top to bottom. All investigated adsorbates prefer oxygen sites on MgO surface. The analysis of adsorbate-MgO(001) electronic structure suggested that the electronic structure of the O adsorption center and adsorbate atom is molecule-like and there is no strong interaction with MgO electronic bands. Based on the obtained dataset for adsorption energies of selected non-metallic adsorbates (X) the reactivity of MgO towards the bond cleavage in the cases of X-X, H-X and HO-X bonds was discussed. Obtained results point to weak reactivity of MgO(001) towards atomic adsorption and low activity for bond cleavage. However, these results can be used as a starting point for the functionalization of MgO, particularly in the cases where bond cleavage activity and surface-mediated stabilization of dissociation products are desired.

  8. Solvothermal synthesis of different phase N-TiO2 and their kinetics, isotherm and thermodynamic studies on the adsorption of methyl orange.

    PubMed

    Fan, Jimin; Zhao, Zhihuan; Liu, Wenhui; Xue, Yongqiang; Yin, Shu

    2016-05-15

    The different crystal forms of nitrogen doped-titanium oxide (N-TiO2) with different particle sizes were produced by precipitation-solvothermal method and their adsorption mechanism were also investigated. The adsorption kinetics showed that rutile N-TiO2 displayed higher adsorption capacity than anatase for methyl orange (MO) and its adsorption behavior followed the pseudo-second-order kinetics. The equilibrium adsorption rate of N-TiO2 for MO was well fitted by the Langmuir isotherm model and the adsorption process was monolayer adsorption. The adsorption capacity decreased with increasing temperature. The average correlation coefficient was beyond 97%. The thermodynamic parameters (ΔaGm(ө), ΔaHm(ө), and ΔaSm(ө)) were calculated. It was found that anatase and rutile N-TiO2 had different adsorption enthalpy and entropy. The smaller the particle size, the greater the surface area and surface energy was, then ΔaGm(ө) decreased and the standard equilibrium constant increased at the same time. The adsorption process onto different crystalline phase N-TiO2 was exothermic and non-spontaneous. PMID:26945716

  9. Equilibrium and kinetic adsorption study of Basic Yellow 28 and Basic Red 46 by a boron industry waste.

    PubMed

    Olgun, Asim; Atar, Necip

    2009-01-15

    In this study, the adsorption characteristics of Basic Yellow 28 (BY 28) and Basic Red 46 (BR 46) onto boron waste (BW), a waste produced from boron processing plant were investigated. The equilibrium adsorption isotherms and kinetics were investigated. The adsorption equilibrium data were analyzed by using various adsorption isotherm models and the results have shown that adsorption behavior of two dyes could be described reasonably well by a generalized isotherm. Kinetic studies indicated that the kinetics of the adsorption of BY 28 and BR 46 onto BW follows a pseudo-second-order model. The result showed that the BW exhibited high-adsorption capacity for basic dyes and the capacity slightly decreased with increasing temperature. The maximum adsorption capacities of BY 28 and BR 46 are reported at 75.00 and 74.73mgg(-1), respectively. The dye adsorption depended on the initial pH of the solution with maximum uptake occurring at about pH 9 and electrokinetic behavior of BW. Activation energy of 15.23kJ/mol for BY 28 and 18.15kJ/mol for BR 46 were determined confirming the nature of the physisorption onto BW. These results indicate that BW could be employed as low-cost material for the removal of the textile dyes from effluents. PMID:18434000

  10. Indigo adsorption on a silicate surface: a theoretical density functional study.

    PubMed

    Iuga, Cristina; Sainz-Díaz, C Ignacio; Ortíz, Elba; Vivier-Bunge, Annik

    2014-07-01

    The applicability of naturally available low-cost and eco-friendly adsorbent materials for the removal of hazardous dyes from aqueous waste is of increasing environmental interest. Among the adsorption treatments available, clays seem to be economically attractive due to their abundance and adsorption capabilities. Indeed, many ancient coloring materials utilized clays mixed with natural dyes (e.g., indigo in Maya Blue). In this work, we performed a quantum-mechanical theoretical study of the adsorption of the indigo molecule onto the (001) surface of a phyllosilicate. Different methods and approaches were applied and compared. We found that the presence of a tetrahedral charge and a sodium counterion significantly increased the adsorption energy of the indigo molecule. The vibrational spectrum of the dye-surface system was also studied, and some interesting shifts in the frequencies of the main vibrational modes of indigo due to its interaction with the surface of the clay mineral were identified. PMID:24958302

  11. Adsorption of polyiodobenzene molecules on the Pt(111) surface using van der Waals density functional theory

    NASA Astrophysics Data System (ADS)

    Johnston, Karen; Pekoz, Rengin; Donadio, Davide

    2016-02-01

    Adsorption of aromatic molecules on surfaces is widely studied due to applications in molecular electronics. In this work, the adsorption of iodobenzene molecules on the Pt(111) surface has been studied using density functional theory. Iodobenzene molecules, with various numbers of iodine atoms, have two non-dissociative adsorption minima. One structure exhibits chemisorption between the ring and the surface (short-range) and the other structure exhibits chemisorption between the iodine ions and the surface (long-range). Both structures have a strong van der Waals interaction with the surface. In general, the adsorption energy increases as the number of iodine atoms increases. The dissociated structure of monoiodobenzene was investigated, and the dissociation barrier and the barrier between the short- and long-range states were compared.

  12. Nickel oxide grafted andic soil for efficient cesium removal from aqueous solution: adsorption behavior and mechanisms.

    PubMed

    Ding, Dahu; Lei, Zhongfang; Yang, Yingnan; Feng, Chuanping; Zhang, Zhenya

    2013-10-23

    An andic soil, akadama clay, was modified with nickel oxide and tested for its potential application in the removal of cesium from aqueous solution. Scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), and powder X-ray diffraction (XRD) results revealed the nickel oxide was successfully grafted into akadama clay. N2 adsorption-desorption isotherms indicated the surface area decreased remarkably after modification while the portion of mesopores increased greatly. Thermogravimetric-differential thermal analysis (TG-DTA) showed the modified akadama clay had better thermostability than the pristine akadama clay. Decreases in cation exchange capacity (CEC) and ζ-potential were also detected after the modification. Adsorption kinetic and isotherm studies indicated the adsorption of Cs+ on the modified akadama clay was a monolayer adsorption process. Adsorption capacity was greatly enhanced for the modified akadama clay probably due to the increase in negative surface charge caused by the modification. The adsorption of Cs+ on the modified akadama clay was dominated by an electrostatic adsorption process. Results of this work are of great significance for the application of akadama clay as a promising adsorbent material for cesium removal from aqueous solutions. PMID:24045068

  13. On the physical adsorption of vapors by microporous carbons

    SciTech Connect

    Bradley, R.H. . Inst. of Surface Science and Technology); Rand, B. . Division of Ceramics)

    1995-01-01

    The physical adsorption of nonpolar and polar vapors by active carbons is discussed in relation to pore structure and pore wall chemistry. For nonpolar vapors the Dubinin-Radushkevich equation is used to derive micropore volumes (W[sub 0]), average adsorption energies (E[sub 0]), and micropore widths (L) for a number of systems. These parameters are used to interpret the adsorption behavior of nitrogen which, because it is a relatively small molecule, is frequently used at 77 K to probe porosity and surface area. Results are presented for three carbons from differing precursors, namely, coal, coconut shells, and polyvinylidene chloride (PVDC) to illustrate the applicability of the technique. For the latter carbon increases in micropore size, induced by activation in carbon dioxide, and reductions in accessible pore volume caused by heat treatment in argon are also characterized and related to structural changes. The approach is then extended to the adsorption of larger hydrogen vapors, where the resulting W[sub 0] values may require correction for molecular packing effects which occur in the lower relative pressure regions of the isotherms, i.e., during the filling of ultramicropores. These packing effects are shown to limit the use of the Polanyi characteristic curve for correlating isotherm data for several vapors, of differing molecular size, by one adsorbent. Data for the adsorption of water, which is a strongly polar liquid, have been interpreted using the Dubinin-Serpinsky equation.

  14. Aqueous mercury adsorption by activated carbons.

    PubMed

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

    2015-04-15

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

  15. Energy budget closure and field scale estimation of canopy energy storage with increased and sustained turbulence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Eddy Covariance (EC) is widely used for direct, non-invasive observations of land-atmosphere energy and mass fluxes. However, EC observations of available energy fluxes are usually less than fluxes inferred from radiometer and soil heat flux observations; thus introducing additional uncertainty in u...

  16. Reductions in entree energy density increase children's vegetable intake and reduce energy intake

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The energy density (ED; kcal/g) of an entrée influences children's energy intake (EI), but the effect of simultaneously changing both ED and portion size of an entrée on preschool children's EI is unknown. In this within-subject crossover study, 3- to 5-year-old children (30 boys, 31 girls) in a day...

  17. Increased use of Renewable Energy in Africa through a Program of Energy Enterprise Development and Investment

    SciTech Connect

    Christine Eibs Singer

    2005-03-11

    To provide training in enterprise development and technical applications, local partner capacity building, individualized enterprise development services and seed capital investment to catalyze the creation of sustainable renewable energy enterprises that deliver clean energy services to households and businesses in South Africa, Ethiopia and Tanzania.

  18. Hydrogen adsorption in ZIF-7: A DFT and ab-initio molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Dixit, Mudit; Major, Dan Thomas; Pal, Sourav

    2016-05-01

    Primary H2 adsorption sites in a zeolitic imidazolate framework, ZIF-7, are identified using ab-initio density functional theory (DFT) based molecular dynamics annealing simulations. The simulations suggest several low energy adsorption sites. The effect of light transition metal decoration on hydrogen storage properties was studied. Our ab-intio DFT calculations illustrate that decorating the ZIF with Sc increases both the number of H2 molecules, as well as the H2 binding energy. The binding energy (∼25 kJ/mol per H2) at 8H2 loading in the pore, suggests that Sc-ZIFs can be potential candidates for hydrogen storage.

  19. The corrosive influence of chloride ions preference adsorption on α-Al2O3 (0 0 0 1) surface

    NASA Astrophysics Data System (ADS)

    Zhang, Chuan-Hui; Liu, Min; Jin, Ying; Sun, Dong-Bai

    2015-08-01

    Conductor-like screening model (COSMO), Periodic DFT calculations have been performed on a Al2O3 surface to model the influence of preference adsorption and interaction of chloride ions at increasing monolayer coverage on undefective passive film on Aluminum in solution environment. The results evidence that the critical monolayer of Cl- is 3/7, which is redefined. With increasing Cl- adsorption, both the first and second Cl- move from Al(1) atop and bridge10 sites to O(5) sites, suggesting that the weaker interaction between Cl- and Al2O3 surface but stronger interactions between three ions make the electrons uniformly occupy on the energy levels of them. More calculations shows that the preference adsorption sites of Cl- are independent of the surface area of oxide, and the adsorption energy decrease in three steps, each adsorption energy step only relate to the adsorption site and the morphology. On undefective oxide film, low coverage Cl- adsorption would restrain surface breakdown to happen which is consistent with the experiment results.

  20. Adsorption of metal ions onto Moroccan stevensite: kinetic and isotherm studies.

    PubMed

    Benhammou, A; Yaacoubi, A; Nibou, L; Tanouti, B

    2005-02-15

    The aim of this paper is to study the adsorption of the heavy metals (Cd(II), Cu(II), Mn(II), Pb(II), and Zn(II)) from aqueous solutions by a natural Moroccan stevensite called locally rhassoul. We carried out, first, a mineralogical and physicochemical characterization of stevensite. The surface area is 134 m2/g and the cation exchange capacity (CEC) is 76.5 meq/100 g. The chemical formula of stevensite is Si3.78Al0.22Mg2.92Fe0.09Na0.08K0.08O10(OH)2.4H2O. Adsorption tests of Cd(II), Cu(II), Mn(II), Pb(II), and Zn(II) in batch reactors were carried out at ambient temperature and at constant pH. Two simplified models including pseudo-first-order and pseudo-second- order were used to test the adsorption kinetics. The equilibrium time and adsorption rate of adsorption were determined. The increasing order of the adsorption rates follows the sequence Mn(II) > Pb(II) > Zn(II) > Cu(II) > Cd(II). The Dubinin-Radushkevich (D-R), Langmuir, and Redlich-Peterson (R-P) models were adopted to describe the adsorption isotherms. The maximal adsorption capacities at pH 4.0 determined from the D-R and Langmuir models vary in the following order: Cu(II) > Mn(II) > Cd(II) > Zn(II) > Pb(II). The equilibrium data fitted well with the three-parameter Redlich-Peterson model. The values of mean energy of adsorption show mainly an ion-exchange mechanism. Also, the influence of solution pH on the adsorption onto stevensite was studied in the pH range 1.5-7.0. PMID:15589536

  1. Adsorption of octylamine on titanium dioxide

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

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

  2. Adsorption Properties of Triethylene Glycol on a Hydrated {101̅4} Calcite Surface and Its Effect on Adsorbed Water.

    PubMed

    Olsen, Richard; Leirvik, Kim N; Kvamme, Bjørn; Kuznetsova, Tatiana

    2015-08-11

    Molecular dynamics (MD) and Born-Oppenheimer MD (BOMD) simulations were employed to investigate adsorption of aqueous triethylene glycol (TEG) on a hydrated {101̅4} calcite surface at 298 K. We analyzed the orientation of TEG adsorbed on calcite, as well as the impact of TEG on the water density and adsorption free energy. The adsorption energies of TEG, free energy profiles for TEG, details of hydrogen bonding between water and adsorbed TEG, and dihedral angle distribution of adsorbed TEG were estimated. We found that while the first layer of water was mostly unaffected by the presence of adsorbed TEG, the density of the second water layer was decreased by 71% at 75% surface coverage of TEG. TEG primarily attached to the calcite surface via two adjacent adsorption sites. Hydrogen bonds between water and adsorbed TEG in the second layer almost exclusively involved the hydroxyl oxygen of TEG. The adsorption energy of TEG on calcite in a vacuum environment calculated by classical MD amounted to 217 kJ/mol, which agreed very well with estimates found by using BOMD. Adsorption on hydrated calcite yielded a drastically lower value of 33 kJ/mol, with the corresponding adsorption free energy of 55.3 kJ/mol, giving an entropy increase of 22.3 kJ/mol due to adsorption. We found that the presence of TEG resulted in a decreased magnitude of the adsorption free energy of water, thus decreasing the calcite wettability. This effect can have a profound effect on oil and gas reservoir properties and must be carefully considered when evaluating the risk of hydrate nucleation. PMID:26161580

  3. Assessing the regional impacts of increased energy maize cultivation on farmland birds.

    PubMed

    Brandt, Karoline; Glemnitz, Michael

    2014-02-01

    The increasing cultivation of energy crops in Germany substantially affects the habitat function of agricultural landscapes. Precise ex ante evaluations regarding the impacts of this cultivation on farmland bird populations are rare. The objective of this paper was to implement a methodology to assess the regional impacts of increasing energy maize cultivation on the habitat quality of agricultural lands for farmland birds. We selected five farmland bird indicator species with varying habitat demands. Using a crop suitability modelling approach, we analysed the availability of potential habitat areas according to different land use scenarios for a real landscape in Northeast Germany. The model was based on crop architecture, cultivation period, and landscape preconditions. Our results showed that the habitat suitability of different crops varied between bird species, and scenario calculations revealed an increase and a decrease in the size of the potential breeding and feeding habitats, respectively. The effects observed in scenario 1 (increased energy maize by 15%) were not reproduced in all cases in scenario 2 (increased energy maize by 30%). Spatial aggregation of energy maize resulted in a negative effect for some species. Changes in the composition of the farmland bird communities, the negative effects on farmland bird species limited in distribution and spread and the relevance of the type of agricultural land use being replaced by energy crops are also discussed. In conclusion, we suggest a trade-off between biodiversity and energy targets by identifying biodiversity-friendly energy cropping systems. PMID:24323319

  4. Potential benefits of R and D directed toward increasing the cost-effectiveness of energy use

    SciTech Connect

    Anderson, T.D.

    1982-03-17

    The need for energy research programs directed toward increasing the cost-effectiveness of energy use is discussed. Benefits reaped by society as a consequence of successful completion of a research activity are economic, environmental, health and safety, security, and long term; emphasis is placed on the economic benefits from research projects on the demand side (i.e., energy end-use sectors). Each end-use sector was examined and data on the amount of energy consumed and the estimated cost of that energy are compiled.

  5. Oxytocin in the ventromedial hypothalamic nucleus reduces feeding and acutely increases energy expenditure

    PubMed Central

    Noble, Emily E.; Billington, Charles J.; Kotz, Catherine M.

    2014-01-01

    Central oxytocin reduces food intake and increases energy expenditure. The ventromedial hypothalamic nucleus (VMN) is associated with energy balance and contains a high density of oxytocin receptors. We hypothesized that oxytocin in the VMN is a negative regulator of energy balance acting to reduce feeding and increase energy expenditure. To test this idea, oxytocin or vehicle was injected directly into the VMN of Sprague-Dawley rats during fasted and nonfasted conditions. Energy expenditure (via indirect calorimetry) and spontaneous physical activity (SPA) were recorded simultaneously. Animals were also exposed to a conditioned taste aversion test, to determine whether oxytocin's effects on food intake were associated with malaise. When food was available during testing, oxytocin-induced elevations in energy expenditure lasted for 1 h, after which overall energy expenditure was reduced. In the absence of food during the testing period, oxytocin similarly increased energy expenditure during the first hour, but differences in 12-h energy expenditure were eliminated, implying that the differences may have been due to the thermic effects of feeding (digestion, absorption, and metabolic processing). Oxytocin acutely elevated SPA and reduced feeding at doses that did not cause a conditioned taste aversion during both the fed and fasted states. Together, these data suggest that oxytocin in the VMN promotes satiety and acutely elevates energy expenditure and SPA and implicates the VMN as a relevant site for the antiobesity effects of oxytocin. PMID:24990860

  6. Oxytocin in the ventromedial hypothalamic nucleus reduces feeding and acutely increases energy expenditure.

    PubMed

    Noble, Emily E; Billington, Charles J; Kotz, Catherine M; Wang, ChuanFeng

    2014-09-15

    Central oxytocin reduces food intake and increases energy expenditure. The ventromedial hypothalamic nucleus (VMN) is associated with energy balance and contains a high density of oxytocin receptors. We hypothesized that oxytocin in the VMN is a negative regulator of energy balance acting to reduce feeding and increase energy expenditure. To test this idea, oxytocin or vehicle was injected directly into the VMN of Sprague-Dawley rats during fasted and nonfasted conditions. Energy expenditure (via indirect calorimetry) and spontaneous physical activity (SPA) were recorded simultaneously. Animals were also exposed to a conditioned taste aversion test, to determine whether oxytocin's effects on food intake were associated with malaise. When food was available during testing, oxytocin-induced elevations in energy expenditure lasted for 1 h, after which overall energy expenditure was reduced. In the absence of food during the testing period, oxytocin similarly increased energy expenditure during the first hour, but differences in 12-h energy expenditure were eliminated, implying that the differences may have been due to the thermic effects of feeding (digestion, absorption, and metabolic processing). Oxytocin acutely elevated SPA and reduced feeding at doses that did not cause a conditioned taste aversion during both the fed and fasted states. Together, these data suggest that oxytocin in the VMN promotes satiety and acutely elevates energy expenditure and SPA and implicates the VMN as a relevant site for the antiobesity effects of oxytocin. PMID:24990860

  7. The unintended energy impacts of increased nitrate contamination from biofuels production.

    PubMed

    Twomey, Kelly M; Stillwell, Ashlynn S; Webber, Michael E

    2010-01-01

    Increases in corn cultivation for biofuels production, due to the Energy Independence and Security Act of 2007, are likely to lead to increases in nitrate concentrations in both surface and groundwater resources in the United States. These increases might trigger the requirement for additional energy consumption for water treatment to remove the nitrates. While these increasing concentrations of nitrate might pose a human health concern, most water resources were found to be within current maximum contaminant level (MCL) limits of 10 mg L(-1) NO(3)-N. When water resources exceed this MCL, energy-intensive drinking water treatment is required to reduce nitrate levels below 10 mg L(-1). Based on prior estimates of water supplies currently exceeding the nitrate MCL, we calculate that advanced drinking water treatment might require an additional 2360 million kWh annually (for nitrate affected areas only)--a 2100% increase in energy requirements for water treatment in those same areas--to mitigate nitrate contamination and meet the MCL requirement. We predict that projected increases in nitrate contamination in water may impact the energy consumed in the water treatment sector, because of the convergence of several related trends: (1) increasing cornstarch-based ethanol production, (2) increasing nutrient loading in surface water and groundwater resources as a consequence of increased corn-based ethanol production, (3) additional drinking water sources that exceed the MCL for nitrate, and (4) potentially more stringent drinking water standards for nitrate. PMID:20082016

  8. Electrical swing adsorption gas storage and delivery system

    DOEpatents

    Judkins, Roddie R.; Burchell, Timothy D.

    1999-01-01

    Systems and methods for electrical swing natural gas adsorption are described. An apparatus includes a pressure vessel; an electrically conductive gas adsorptive material located within the pressure vessel; and an electric power supply electrically connected to said adsorptive material. The adsorptive material can be a carbon fiber composite molecular sieve (CFCMS). The systems and methods provide advantages in that both a high energy density and a high ratio of delivered to stored gas are provided.

  9. Electrical swing adsorption gas storage and delivery system

    DOEpatents

    Judkins, R.R.; Burchell, T.D.

    1999-06-15

    Systems and methods for electrical swing natural gas adsorption are described. An apparatus includes a pressure vessel; an electrically conductive gas adsorptive material located within the pressure vessel; and an electric power supply electrically connected to said adsorptive material. The adsorptive material can be a carbon fiber composite molecular sieve (CFCMS). The systems and methods provide advantages in that both a high energy density and a high ratio of delivered to stored gas are provided. 5 figs.

  10. 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.

  11. Easing the natural gas crisis: Reducing natural gas prices through increased deployment of renewable energy and energy efficiency

    SciTech Connect

    Wiser, Ryan; Bolinger, Mark; St. Clair, Matt

    2004-12-21

    Heightened natural gas prices have emerged as a key energy-policy challenge for at least the early part of the 21st century. With the recent run-up in gas prices and the expected continuation of volatile and high prices in the near future, a growing number of voices are calling for increased diversification of energy supplies. Proponents of renewable energy and energy efficiency identify these clean energy sources as an important part of the solution. Increased deployment of renewable energy (RE) and energy efficiency (EE) can hedge natural gas price risk in more than one way, but this paper touches on just one potential benefit: displacement of gas-fired electricity generation, which reduces natural gas demand and thus puts downward pressure on gas prices. Many recent modeling studies of increased RE and EE deployment have demonstrated that this ''secondary'' effect of lowering natural gas prices could be significant; as a result, this effect is increasingly cited as justification for policies promoting RE and EE. This paper summarizes recent studies that have evaluated the gas-price-reduction effect of RE and EE deployment, analyzes the results of these studies in light of economic theory and other research, reviews the reasonableness of the effect as portrayed in modeling studies, and develops a simple tool that can be used to evaluate the impact of RE and EE on gas prices without relying on a complex national energy model. Key findings are summarized.

  12. Calcium decorated and doped phosphorene for gas adsorption

    NASA Astrophysics Data System (ADS)

    Lalitha, Murugan; Nataraj, Yuvarani; Lakshmipathi, Senthilkumar

    2016-07-01

    In this paper, we present the results from first-principles study based on the electronic structure and adsorption characteristics of CH4, CO2, H2 and NH3 adsorbed on Ca decorated/doped phosphorene. Our study finds that phosphorene exhibits n-type behaviour on decorating calcium, and p-type on doping calcium. Gas molecules are physisorbed on both pristine and calcium-mediated phosphorene, visible through their lower binding energy and charge transfer values. Ca decorated phosphorene is suitable for hydrogen storage due to its higher binding energy for H2. Ca doped structures shows increased binding affinity towards CH4 and NH3 in zigzag1 direction and armchair directions respectively. The extracts of our study implies that Ca doped phosphorene possess increased binding affinity towards gas molecules, and the results are highly helpful for gas adsorption and to design gas sensors based on calcium doped or decorated phosphorene.

  13. European Union energy policy integration: A case of European Commission policy entrepreneurship and increasing supranationalism

    PubMed Central

    Maltby, Tomas

    2013-01-01

    Focusing on gas, this article explores the role of the European Commission in the process of European Union energy security policy development, and the extent to which the policy area is becoming increasingly supranational. Situating the article within the literature on agenda-setting and framing, it is argued that a policy window was opened as a result of: enlargement to include more energy import dependent states, a trend of increasing energy imports and prices, and gas supply disruptions. From the mid-2000s, the Commission contributed to a shift in political norms, successfully framing import dependency as a problem requiring an EU-level solution, based on the institution’s pre-existing preferences for a diversified energy supply and internal energy market. Whilst Member States retain significant sovereignty, the Commission has achieved since 2006 creeping competencies in the internal, and to a lesser extent external, dimensions of EU energy policy. PMID:24926115

  14. European Union energy policy integration: A case of European Commission policy entrepreneurship and increasing supranationalism.

    PubMed

    Maltby, Tomas

    2013-04-01

    Focusing on gas, this article explores the role of the European Commission in the process of European Union energy security policy development, and the extent to which the policy area is becoming increasingly supranational. Situating the article within the literature on agenda-setting and framing, it is argued that a policy window was opened as a result of: enlargement to include more energy import dependent states, a trend of increasing energy imports and prices, and gas supply disruptions. From the mid-2000s, the Commission contributed to a shift in political norms, successfully framing import dependency as a problem requiring an EU-level solution, based on the institution's pre-existing preferences for a diversified energy supply and internal energy market. Whilst Member States retain significant sovereignty, the Commission has achieved since 2006 creeping competencies in the internal, and to a lesser extent external, dimensions of EU energy policy. PMID:24926115

  15. Size dependent adsorption on nanocrystal surfaces

    NASA Astrophysics Data System (ADS)

    Lu, H. M.; Wen, Z.; Jiang, Q.

    2005-03-01

    A quantitative thermodynamic correlation method to describe the size dependent Langmuir adsorption isotherm is developed. According to the model, the equilibrium adsorption constant increases as material size decreases, which is in agreement with the literature data of acetic acid, valeric acid, oxalic acid, and adipic acid on anatase nanoparticles.

  16. Nucleation and interfacial adsorption in ternary systems.

    PubMed

    Philippe, T

    2015-03-01

    Nucleation is studied in incompressible ternary fluids by examining the topology of the overall landscape of the energy surface. Minimum free energy paths for nucleation (MFEPs) of a single nucleus in an infinite matrix are computed with the string method in the framework of the continuum theory of nucleation for the regular solution. Properties of the critical nucleus are compared with the predictions of the classical nucleation theory. MFEPs are found to exhibit complex nucleation pathways with non-monotonic variations of compositions in the interfacial region, specifically adsorption of a component. In the symmetric regular solution, the minority component is found to segregate at the interface during nucleation with a concomitant depletion of the nucleus core, resulting in unpredicted partition of the non-selective component. Despite increasing the gradient energy, such inhomogeneity in composition is shown to lower the nucleation barrier. PMID:25747088

  17. Adsorption sites, adsorption enthalpies and potential removal of terpenoids by atmospheric ice

    NASA Astrophysics Data System (ADS)

    Czech, Christian; Hammer, Sonja M.; Bonn, Boris; Schmidt, Martin U.

    2011-01-01

    Ice crystal formation and its effect on atmospheric trace gases are currently an important area of research because of its radiation and climate effects. However, the processes of adsorption of trace gases on ice surfaces and absorption into ice crystals are poorly understood. Both processes are investigated by lattice-energy minimisation for a selected number of atmospherically relevant volatile organic compounds, i.e. isoprene, methacrolein, acetone, methylbutenol, perillyl alcohol and 2,10-pinanediol, which can be considered as exemplary substances for similar structured compounds. Adsorption and absorption geometries and enthalpies are computed and the potential uptake strength is approximated. According to our calculations non-polar terpenes like isoprene are not significantly adsorbed by ice crystals. Oxidized terpenoids have stronger interactions with the ice surface (at least two hydrogen bonds) leading to larger adsorption enthalpies. Absorption into the ice crystal plays only a minor role. Correspondingly, in the atmosphere terpenoid compounds are increasingly adsorbed to ice surfaces with increasing oxygen numbers. Subsequently this process can contribute to the wet removal of terpenoids by ice, which is so far ignored in global transport models.

  18. Influence of strain on water adsorption and dissociation on rutile TiO2(110) surface.

    PubMed

    Yang, Long; Shu, Da-Jun; Li, Shao-Chun; Wang, Mu

    2016-06-01

    The influence of externally applied strain on water adsorption and dissociation on a defect-free rutile TiO2(110) surface is studied by using first-principles calculations. We found that while compressive strain makes water adsorption and dissociation less favorable, tensile strain increases the energy gain of water adsorption, and decreases the energy cost of water dissociation. Specifically, dissociative water becomes more stable than molecular water when an 8% tensile in-plane strain is applied. Moreover, the dissociation barrier decreases with increasing strain more rapidly for more isolated water. The rate of decrease of this barrier for nearly isolated water is 0.017 eV per 1% biaxial strain. This demonstrates that applying strain is a possible way to engineer the surface adsorption and dissociation of water on a TiO2(110) surface, and therefore engineer the relevant surface reactivity. PMID:27138099

  19. Section 502(e) guidance providing credit toward energy efficiency goals for cost-effective projects where source energy use declines but site energy use increases

    SciTech Connect

    None, None

    2004-10-01

    Outlines how Section 502(e) of Executive Order 13123 requires the Secretary of Energy to “issue guidance for providing credit toward energy efficiency goals for cost-effective projects where source energy use declines but site energy use increases."

  20. Carbon monoxide adsorption on beryllium surfaces

    NASA Astrophysics Data System (ADS)

    Allouche, A.

    2013-02-01

    Density functional calculations are here carried out to study the carbon monoxide molecule adsorption on pristine, hydrogenated and hydroxylated beryllium Be (0001) surfaces. The adsorption energies and structures, the activation barriers to molecular adsorption and dissociation are calculated. These reactions are described in terms of potential energy surfaces and electronic density of states. The quantum results are discussed along two directions: the beryllium surface reactivity in the domain of nuclear fusion devices and the possible usage of beryllium as a catalyst of Fischer-Tropsch-type synthesis.

  1. Adsorptive desulfurization and denitrogenation using metal-organic frameworks.

    PubMed

    Ahmed, Imteaz; Jhung, Sung Hwa

    2016-01-15

    With the increasing worldwide demand for energy, utilization of fossil fuels is increasing proportionally. Additionally, new and unconventional energy sources are also being utilized at an increasing rate day-by-day. These sources, along with some industrial processes, result in the exposal of several sulfur- and nitrogen-containing compounds (SCCs and NCCs, respectively) to the environment, and the exposure is one of the greatest environmental threats in the recent years. Although, several methods were established for the removal of these pollutants during the last few decades, recent advancements in adsorptive desulfurization and denitrogenation (ADS and ADN, respectively) with metal-organic frameworks (MOFs) make this the most promising and remarkable method. Therefore, many research groups are currently involved with ADS and ADN with MOFs, and the results are improving gradually by modifying the MOF adsorbents according to several specific adsorption mechanisms. In this review, ADS and ADN studies are thoroughly discussed for both liquid-phase and gas-phase adsorption. The MOF modification procedures, which are important for improved adsorption, are also described. To improve the knowledge among the scientific community, it is very important to understand the detailed chemistry and mechanism involved in a chemical process, which also creates the possibility and pathway for further developments in research and applications. Therefore, the mechanisms related to the adsorption procedures are also discussed in detail. From this review, it can be expected that the scientific community will obtain an understanding of the current state of ADS and ADN, their importance, and some encouragement and insight to take the research knowledge base to a higher level. PMID:26368800

  2. Adsorptive removal of methylene blue by agar: effects of NaCl and ethanol

    PubMed Central

    2012-01-01

    Adsorption of methylene blue (MB) on agar was investigated as a function of temperature (308-328 K), different concentrations of NaCl and HCl and various weight percentages of binary mixtures of ethanol with water. It was observed that the maximum experimental adsorption capacity, qm, exp, in water is up to 50 mg g-1 and decreases with increase in weight percentage of ethanol and NaCl and HCl concentration compared to that of water. Analysis of data using ARIAN model showed that MB adsorbs as monomer and dimer on the surface of agar. Binding constants of MB to agar were calculated using the Temkin isotherm. The process is exothermic in water and other solutions. The mean adsorption energy (E) value indicated binding of MB to agar is chemical adsorption. Kinetics of this interaction obeys from the pseudo-second-order model and diffusion of the MB molecules into the agar is the main rate-controlling step. PMID:22339759

  3. Adsorption of polymer chains at penetrable interfaces

    SciTech Connect

    Gerasimchuk, I. V.; Sommer, J.-U.; Gerasimchuk, V. S.

    2011-03-15

    We investigate the problem of adsorption (localization) of polymer chains in the system of two penetrable interfaces within the mean-field approximation. The saturation of the polymer system in the limit case of zero bulk concentration is studied. We find the exact solution of this mean-field polymer adsorption problem that opens the possibility to treat various localization problems for polymer chains in such environments using appropriate boundary conditions. The exact solution is controlled by a single scaling variable that describes the coupling between the interfaces due to the polymer chains. We obtain a nonmonotonic behavior of the amount of adsorbed polymers as a function of the distance between the interfaces. This leads to a high-energy and a low-energy phase for the double layer with respect to the amount of polymers localized. At the saturation point, we find the total energy of the system and determine the force acting between the interfaces to be strictly attractive and to monotonically decay to zero when the interface distance increases.

  4. Increased food energy supply as a major driver of the obesity epidemic: a global analysis

    PubMed Central

    Chow, Carson C; Hall, Kevin D; Umali, Elaine; Swinburn, Boyd A

    2015-01-01

    Abstract Objective We investigated associations between changes in national food energy supply and in average population body weight. Methods We collected data from 24 high-, 27 middle- and 18 low-income countries on the average measured body weight from global databases, national health and nutrition survey reports and peer-reviewed papers. Changes in average body weight were derived from study pairs that were at least four years apart (various years, 1971–2010). Selected study pairs were considered to be representative of an adolescent or adult population, at national or subnational scale. Food energy supply data were retrieved from the Food and Agriculture Organization of the United Nations food balance sheets. We estimated the population energy requirements at survey time points using Institute of Medicine equations. Finally, we estimated the change in energy intake that could theoretically account for the observed change in average body weight using an experimentally-validated model. Findings In 56 countries, an increase in food energy supply was associated with an increase in average body weight. In 45 countries, the increase in food energy supply was higher than the model-predicted increase in energy intake. The association between change in food energy supply and change in body weight was statistically significant overall and for high-income countries (P < 0.001). Conclusion The findings suggest that increases in food energy supply are sufficient to explain increases in average population body weight, especially in high-income countries. Policy efforts are needed to improve the healthiness of food systems and environments to reduce global obesity. PMID:26170502

  5. DFT modelling of hydrogen sulphide adsorption on α-Cr2O3 (0001) surface

    NASA Astrophysics Data System (ADS)

    Maldonado, Frank; Stashans, Arvids

    2016-05-01

    Density functional theory has been used to predict properties of hydrogen sulphide, H2S, adsorption on the α-Cr2O3 (0001) surface. Five energetically most favourable adsorption configurations have been selected for the study. Our work reveals adsorption geometries as well as discusses electronic and magnetic properties of the adsorbate on chromium oxide surface. It is shown that two different adsorption types, namely molecular adsorption and dissociative adsorption, can take place leading to two sets of adsorption energies. The most favourable arrangement is found to correspond to the case of dissociative adsorption with molecular hydrogen forming OH group at the α-Cr2O3 (0001) surface.

  6. Adsorption and desorption behavior of herbicide diuron on various Chinese cultivated soils.

    PubMed

    Liu, Yihua; Xu, Zhenzhen; Wu, Xiaoguang; Gui, Wenjun; Zhu, Guonian

    2010-06-15

    The adsorption-desorption behaviors of diuron were investigated in six cultivated soils of China. The effect of system pH and temperature were also studied. The data fitted the Freundlich equation very well. The adsorption K(F) values indicated the adsorption of diuron in the six soils was in the sequence of black soil (D)>yellow earth (F)>paddy soil (B)>yellow-brown soil (C)>yellow-cinnamon soil (A)>lateritic red earth (E). The adsorption K(F) and Freundlich exponents n were decreased when temperature was increased from 298 K to 318 K. However, the Gibb's free energy values were found less negative with the increasing temperature. Meanwhile, the extent of diuron adsorption on soil was at rather high level under low pH value conditions and decreased with increasing pH value. In addition, the desorption behavior of diuron in the six soils was in the sequence of lateritic red earth (E)>yellow-cinnamon soil (A)>paddy soil (B)>yellow earth (F)>yellow-brown soil (C)>black soil (D). At the same time, desorption hysteresis of diuron were observed in all of the tested soils. And the soil organic matter content may play an important role in the adsorption-desorption behavior. PMID:20153105

  7. Adsorption of Pb(II), Cr(III), Cu(II), Cd(II) and Ni(II) onto a vanadium mine tailing from aqueous solution.

    PubMed

    Shi, Taihong; Jia, Shiguo; Chen, Ying; Wen, Yinghong; Du, Changming; Guo, Huilin; Wang, Zhuochao

    2009-09-30

    The adsorption of heavy metal cations Pb(II), Cr(III), Cu(II), Cd(II) and Ni(II) from aqueous solution by a mine tailing which mainly contains muscovite was investigated. The property of the mineral was investigated by using SEM, FT-IR, XRD and BET analysis. pH(pzc) was measured by an titration technique to give a value of 5.4+/-0.1. Kinetics experiments indicated that the processes can be simulated by pseudo-second-order model. Total adsorption amounts of the heavy metal increased, while the adsorption density decreased when the solid-to-liquid ratio (S/L) increased. Grain size did not affect the adsorption capacity significantly. The resulting isotherms can be described by Frendlich relationship. And the maximum adsorption capacity (molar basis) followed the order of Cr(III)>Pb(II)>Cu(II)>Ni(II)>Cd(II). Thermodynamic analysis showed that the adsorption processed were endothermic and may be chemical in nature with positive DeltaH(0). The positive DeltaS(0) suggested that dissociative processed were involved. Small positive DeltaG(0) suggested that the adsorption processes required a small amount of energy. Adsorption processes were slightly affected by electrolyte ion concentration but strongly dependent on pH value. The most possible mechanism of the adsorption processes involve the inner-sphere-complexions by the aluminol or silanol groups on the surface of the mineral. PMID:19427115

  8. Comparing the removal of perchlorate when using single-walled carbon nanotubes (SWCNTs) or granular activated carbon: adsorption kinetics and thermodynamics.

    PubMed

    Lou, Jie C; Hsu, Yung S; Hsu, Kai L; Chou, Ming S; Han, Jia Y

    2014-01-01

    This study aims to remove perchlorate using single-walled carbon nanotubes (SWCNTs) or granular activated carbon (GAC). Dynamic and equilibrium adsorption experiments were performed to evaluate the thermodynamic behavior of perchlorate on SWCNTs and GAC. Key parameters affecting the adsorption, such as pH, ionic strength, and temperature were studied. The experimental results showed that the dynamic adsorption experiment achieved equilibrium in approximately eight hours. The adsorption capacity increased as the concentration of perchlorate increased or as the ionic strength decreased. The selected adsorption models were the modified Freundlich, the pseudo-1st-order, and the pseudo-2nd-order equations. The results showed that the modified Freundlich equation best described the kinetic adsorption processes. The maximal adsorption capacities of GAC and SWCNTs were 33.87-28.21 mg/g and 13.64 - 10.03 mg/g, respectively, at a constant temperature between 5°C and 45°C. The thermodynamic parameters, such as the equilibrium constant (K0 ), the standard free energy changes (ΔG°), the standard enthalpy change (ΔH°) and the standard entropy change (ΔS°), were obtained. The results of the isothermal equilibrium adsorption experiment showed that low pH levels, low ionic strength, and low-temperature conditions facilitated the perchlorate adsorption, indicating that GAC and SWCNTs are potential absorbents for water treatment. PMID:24410681

  9. Surface energetics of alkaline-earth metal oxides: Trends in stability and adsorption of small molecules

    NASA Astrophysics Data System (ADS)

    Bajdich, Michal; Nørskov, Jens K.; Vojvodic, Aleksandra

    2015-04-01

    We present a systematic theoretical investigation of the surface properties, stability, and reactivity of rocksalt type alkaline-earth metal oxides including MgO, CaO, SrO, and BaO. The accuracy of commonly used exchange-correlation density functionals (LDA, PBE, RPBE, PBEsol, BEEF-vdW, and hybrid HSE) and random-phase approximation (RPA) is evaluated and compared to existing experimental values. Calculated surface energies of the four most stable surface facets under vacuum conditions, the (100) surface, the metal and oxygen terminated octopolar (111), and the (110) surfaces, exhibit a monotonic increase in stability from MgO to BaO. On the MgO(100) surface, adsorption of CO, NO, and CH4 is characterized by physisorption while H2O chemisorbs, which is in agreement with experimental findings. We further use the on-top metal adsorption of CO and NO molecules to map out the surface energetics of each alkaline-earth metal oxide surface. The considered functionals all qualitatively predict similar adsorption energy trends. The ordering between the adsorption energies on different surface facets can be attributed to differences in the local geometrical surface structure and the electronic structure of the metal constituent of the alkaline-earth metal oxide. The striking observation that CO adsorption strength is weaker than NO adsorption on the (100) terraces as the period of the alkaline-earth metal in the oxide increases is analyzed in detail in terms of charge redistribution within the σ and π channels of adsorbates. Finally, we also present oxygen adsorption and oxygen vacancy formation energies in these oxide systems.

  10. CO adsorption on cobalt: Prediction of stable surface phases

    NASA Astrophysics Data System (ADS)

    Gunasooriya, G. T. Kasun Kalhara; van Bavel, Alexander P.; Kuipers, Herman P. C. E.; Saeys, Mark

    2015-12-01

    Adsorption is often described by a Langmuir isotherm, sometimes accounting for a gradual decrease in the adsorption energy with coverage. Using density functional theory, we show that CO adsorption on cobalt does not follow this typical behavior. Instead, adsorption on Co(0001) is dominated by two surface phases. At low pressures, the (√3 × √3)R30°-CO structure is the stable phase, and CO forms (√3 × √3)R30°-CO islands for coverages below 1/3 ML because of attractive CO-CO interactions. Increasing the pressure does not gradually increase the coverage beyond 1/3 ML. Instead, a transition to a high coverage (2√3 × 2√3)R30°-7CO surface structure occurs at 0.1 mbar at room temperature and at 21 bar at 500 K. These two phases are also the dominant structures that have been characterized experimentally on Co(0001), and the conditions where each phase was observed match the first principle surface phase diagram.

  11. Influence of Soil Solution Salinity on Molybdenum Adsorption by Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Molybdenum (Mo) adsorption on five arid-zone soils from California was investigated as a function of equilibrium solution Mo concentration (0-30 mg L-1), solution pH (4-8), and electrical conductivity (EC = 0.3 or 8 dS m-1). Molybdenum adsorption decreased with increasing pH. An adsorption maximum...

  12. Adsorption of heavy metal from aqueous solution by dehydrated root powder of long-root Eichhornia crassipes.

    PubMed

    Li, Qiang; Chen, Bo; Lin, Peng; Zhou, Jiali; Zhan, Juhong; Shen, Qiuying; Pan, Xuejun

    2016-01-01

    The root powder of long-root Eichhornia crassipes, as a new kind of biodegradable adsorbent, has been tested for aqueous adsorption of Pb, Zn, Cu, and Cd. From FT-IR, we found that the absorption peaks of phosphorous compounds, carbonyl, and nitrogenous compounds displayed obvious changes before and after adsorption which illustrated that plant characteristics may play a role in binding with metals. Surface properties and morphology of the root powders have been characterized by means of SEM and BET. Energy spectrum analysis showed that the metals were adsorbed on root powders after adsorption. Then, optimum quantity of powder, pH values, and metal ion concentrations in single-system and multi-system were detected to discuss the characteristics and mechanisms of metal adsorption. Freundlich model and the second-order kinetics equation could well describe the adsorption of heavy metals in single-metal system. The adsorption of Pb, Zn, and Cd in the multi-metal system decreased with the concentration increased. At last, competitive adsorption of every two metals on root powder proved that Cu and Pb had suppressed the adsorption performance of Cd and Zn. PMID:26605425

  13. [Degradation and adsorption behavior of napropamide in soils].

    PubMed

    Guo, Hua; Zhu, Hong-mei; Yang, Hong

    2008-06-01

    Chromatography (HPLC and GC-MS) and spectroscopy (UV and FT-IR) methods were conducted to study the degradation and adsorption behavior of napropamide in soils. Influence factors of degradation, degradation products and adsorption mechanism were analyzed. The results showed that degradation rate of napropamide increased with enhancing temperature (15-35 degrees C) and organic matter content in soil was the most important factor which influenced the degradation half-life of napropamide in soil, and their relative coefficient (r) reached 0.9794. The degradation half-life of napropamide in sterilized soil was almost 3-fold of that in non-sterilized soil, and soil microorganisms were contributed to the degradation of napropamide. The probable degradation products were N-methyl-2-(1-naphthoxy)-propionamide and N-ethyl-2-(1-naphthoxy)-propionamide. The possible degradation pathways were dealkylation. Adsorption isoterms of napropamide on three soils such as Yellow-brown soil, Latersol and Black Soil could be described by Freundlich equation with the corresponding adsorption coefficient (Kf) of 1.29, 3.43 and 13.36, and the adsorption free energy (delta G) of napropamide on the three soils was less than 40 kJ x mol(-1) which largely resulted from the physical adsorption involving in hydrogen-bonding, hydrophobic bonding, coordination and van der waal force. Comparison to the FT-IR spectra of the three soils, the results certificated that the sorption capacity of three soils was Black Soil > Latersol > Yellow-brown Soil. PMID:18763531

  14. Mesoscopic dynamic Monte Carlo simulations of the adsorption of proteinlike HP chains within laterally constricted spaces.

    PubMed

    Liu, Susan M; Haynes, Charles A

    2005-02-15

    Two-dimensional dynamic Monte Carlo simulations are applied to the protein-like HP chain model to investigate the influence of lateral confinement of the adsorbed chain on adsorption thermodynamics and the ensemble of accessible chain conformations. The structure of the model makes it possible to enumerate all possible chain conformations and thereby define with precision the relation between adsorption thermodynamics and changes in accessible chain conformations resulting from the adsorption process. Lateral confinement of the adsorbed chain is shown to dramatically reduce the number of accessible energy states and unique chain conformations such that, under certain conditions, adsorption is predicted to actually stabilize the chain against denaturation. Lateral confinement preferentially eliminates expanded conformations of the adsorbed chain, shifting the equilibrium from the unfolded state toward the native state. As a result, the conformational entropy of the adsorbed chain is predicted to be lower than that of the chain free in solution. The protein-like HP chain responds to an increase in the hydrophobicity of the sorbent surface by strongly favoring those conformations that minimize the overall internal energy of the system. As a result, adsorption severely destabilizes the native-state conformation. The ability of our simulation results to provide insights into underlying mechanisms for nonspecific protein adsorption is illustrated through qualitative comparison with activity data for hen egg-white lysozyme adsorbed on silica at different surface concentrations. PMID:15589532

  15. Direct Measurement of the Adsorbed Film Volume for Estimating Heats of Adsorption

    NASA Astrophysics Data System (ADS)

    Gillespie, Andrew; Dohnke, Elmar; Rash, Tyler; Stalla, David; Knight, Ernest; Seydel, Florian; Sweany, Mark; Pfeifer, Peter

    Compressed hydrogen and methane require extremely high pressures or low temperatures in order to compete with the energy density of conventional fossil fuels. Adsorbent materials provide a means to increase the energy density of these gasses up to 6 times that of compressed gas at the same temperature and pressure. One major concern in engineering adsorbed gas systems is thermal management during charging and discharging. Adsorption is an exothermic process, releasing heat during charging and absorbing heat during discharging. To estimate the heat of adsorption, it is common to analyze excess adsorption isotherms by converting to absolute adsorption and employ the Clausius Clapeyron relation. However, this method requires an assumed volume of the adsorbed state. It is common for researchers to assume that the adsorbed film occupies the entire pore volume of the adsorbent material. However, the adsorbed film only occupies a fraction of the total pore volume. This yields heats of adsorption that are underestimated by as much as 10kJ/mol at high coverage. In this talk, we present a method to directly measure the adsorbed film volume as a function of temperature and present the resulting heats of adsorption for both methane and hydrogen.

  16. Adsorption of fibrinogen on a biomedical-grade stainless steel 316LVM surface: a PM-IRRAS study of the adsorption thermodynamics, kinetics and secondary structure changes.

    PubMed

    Desroches, Marie-Josee; Omanovic, Sasha

    2008-05-14

    Polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS) was employed to investigate the interaction of serum protein fibrinogen with a biomedical-grade 316LVM stainless steel surface, in terms of the adsorption thermodynamics, kinetics and secondary structure changes of the protein. Apparent Gibbs energy of adsorption values indicated a highly spontaneous and strong adsorption of fibrinogen onto the surface. The kinetics of fibrinogen adsorption were successfully modeled using a pseudo first-order kinetic model. Deconvolution of the amide I bands indicated that the adsorption of fibrinogen on 316LVM results in significant changes in the protein's secondary structure that occur predominantly within the first minute of adsorption. Among the investigated structures, the alpha-helix structure undergoes the smallest changes, while the beta-sheet and beta-turns structures undergo significant changes. It was shown that lateral interactions between the adsorbed molecules do not play a role in controlling the secondary structure changes. An increase in temperature induced changes in the secondary structure of the protein, characterized by a loss of the alpha-helical content and its transformation into the beta-turns structure. PMID:18446250

  17. Adsorption of pyridine by combusted oil shale

    NASA Astrophysics Data System (ADS)

    Essington, M. E.

    1992-03-01

    Large volumes of solid waste material will be produced during the commercial production of shale oil. An alternative to the disposal of the solid waste product is utilization. One potential use of spent oil shale is for the stabilization of hazardous organic compounds. The objective of this study was to examine the adsorption of pyridine, commonly found in oil shale process water, by spent oil shale. The adsorption of pyridine by fresh and weathered samples of combusted New Albany Shale and Green River Formation oil shale was examined. In general, pyridine adsorption can be classified as L-type and the isotherms modeled with the Langmuir and Freundlich equations. For the combusted New Albany Shale, weathering reduced the predicted pyridine adsorption maximum and increased the amount of pyridine adsorbed at low solution concentrations. For the combusted Green River Formation oil shales, weathering increased the predicted pyridine adsorption maximum. The pyridine adsorption isotherms were similar to those produced for a combusted Australian oil shale. Although adsorption can be mathematically described by empirical models, the reduction in solution concentrations of pyridine was generally less than 10 mg/l at an initial concentration of 100 mg/l. Clearly, the observed reduction in solution pyridine concentrations does not sufficiently justify using spent oil shale as a stabilizing medium. However, data in the literature suggest that other organic compounds can be effectively removed from solution by spent oil shale and that adsorption is dependent on process conditions and organic compound type.

  18. Factors affecting the adsorption of xenon on activated carbon

    SciTech Connect

    Underhill, D.W.; DiCello, D.C.; Scaglia, L.A.; Watson, J.A.

    1986-08-01

    The presence of water vapor was found to interfere strongly with the dynamic adsorption of /sup 133/Xe on coconut-base activated charcoal. The percent loss in the xenon adsorption coefficient was similar to values reported earlier for the adsorption of krypton on humidified charcoal. Attempts to increase the adsorption of xenon by (a) using a petroleum-based adsorbent with an extremely high surface area and (b) by impregnation of the adsorbent with iodine were not successful.

  19. Cooking increases net energy gain from a lipid-rich food

    PubMed Central

    Groopman, Emily E.; Carmody, Rachel N.; Wrangham, Richard W.

    2014-01-01

    Starch, protein, and lipid are three major sources of calories in the human diet. The unique and universal human practice of cooking has been demonstrated to increase the energy gained from foods rich in starch or protein. Yet no studies have tested whether cooking has equivalent effects on the energy gained from lipid-rich foods. Using mice as a model, we addressed this question by examining the impact of cooking on the energy gained from peanuts, a lipid-rich oilseed, and compared this impact against that of nonthermal processing (blending). We found that cooking consistently increased the energy gained per calorie, whereas blending had no detectable energetic benefits. Assessment of fecal fat excretion showed increases in lipid digestibility when peanuts were cooked, and examination of diet microstructure revealed concomitant alterations to the integrity of cell walls and the oleosin layer of proteins that otherwise shield lipids from digestive lipases. Both effects were consistent with the greater energy gain observed with cooking. Our findings highlight the importance of cooking in increasing dietary energy returns for humans, both past and present. PMID:25293786

  20. Adsorption behaviour of bulgur.

    PubMed

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

    2016-03-15

    The aim of this research was to determine the adsorption behaviour of bulgur. Three different particle sizes (2increased both with decreasing temperature and bulgur size. The constants m0 and C of BET and GAB equations were determined to be between 2.54 and 5.03 g water per 100 g of dry matter and 4.96-16.57, respectively. Constant k was between 0.85 and 0.93, and GAB equation was determined to fit very well for bulgur adsorption, because of %E values lower than 10%. Bulgur must be stored below 70% relative humidity and with less than 10 g water per 100 g of dry mater. PMID:26575716

  1. Unrestricted density functional study on the adsorption of hydrogen molecule on nickel surface

    NASA Astrophysics Data System (ADS)

    Ishiwatari, Ryo; Tachikawa, Masanori

    2005-02-01

    The adsorption of hydrogen molecule on Ni(100) and (111) surfaces is studied by unrestricted hybrid density functional calculation. Ni6 and Ni8 clusters are used as small single layer models, while Ni13 cluster as a model containing the second layer. The total energy of triplet state is most stable for both Ni6 (100) fourfold and Ni8 (111) threefold sites. We have found that the optimized geometrical parameters become closer to the experimental values, as the multiplicity increases from singlet to quintet states. Our adsorption energy on Ni13 (100) bridge site gives in reasonable agreement with the experimental value.

  2. Adsorption of Benzoic Acid in Aqueous Solution by Bagasse Fly Ash

    NASA Astrophysics Data System (ADS)

    Suresh, S.

    2012-09-01

    This paper reports the studies on the benzoic acid (BA) onto bagasse fly ash (BFA) was studied in aqueous solution in a batch system. Physico-chemical properties including surface area, surface texture of the GAC before and after BA adsorption onto BFA were analysed using X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The optimum initial pH for the adsorption of BA was found to be 5.56. The adsorbent dose was 10 g/l for BFA and the equilibrium time 8 h of reaction. Pseudo first and second order models were used to find the adsorption kinetics. It was found that intraparticle diffusion played important role in the adsorption mechanisms of BA and the adsorption kinetics followed pseudo-second order kinetic model rather than the pseudo first order kinetic model. Isotherm data were generated for BA solution having initial concentrations of BA in the range of 10-200 mg/l for the BFA dosage of 10 g/l at temperatures of 288, 303, and 318 K. The adsorption of BA onto BFA was favorably influenced by an increase in temperature. Equilibrium data were well represented by the Redlich-Peterson isotherm model. Values of the change in entropy ( ΔS 0), heat of adsorption ( ΔH 0) for adsorption of BA on BFA was found to be 120.10 and 19.61 kJ/mol respectively. The adsorption of BA onto BFA was an endothermic reaction. Desorption of BA from BFA was studied by various solvents method. Acetic acid was found to be a better eluant for desorption of BA with a maximum desorption efficiency of 55.2 %. Owing to its heating value, spent BFA can be used as a co-fuel for the production of heat in boiler furnaces.

  3. Enhancement of the anionic dye adsorption capacity of clinoptilolite by Fe(3+)-grafting.

    PubMed

    Akgül, Murat

    2014-02-28

    In this paper, a batch system was applied to study the adsorption behavior of congo red (CR) on raw and modified clinoptilolites. Raw clinoptilolite (Raw-CL) was treated with Fe(NO3)3 in ethanol to obtain its iron-grafted form (Fe-CL). Adsorbents were characterized by X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), energy dispersive X-ray spectroscopy (EDX), thermogravimetric/differential thermal analysis (TG/DTA), zeta-potential measurement and N2 gas adsorption-desorption techniques. Effects of the experimental parameters (initial pH, dye concentration, temperature and adsorption time) were investigated to find optimum conditions that result in highest adsorption capacity for CR removal. The obtained results suggest that the solution pH appears to be a key factor of the CR adsorption process. The maximum dye adsorption was achieved with Fe-CL adsorbent at pH ∼6.3 and the corresponding adsorption capacity was found to be 36.7mg/g, which is higher than that of its raw counterpart (16.9mg/g). A significant decrease in CR removal was given by Fe-CL between pH 7 and 11 opposite to Raw-CL which has nearly constant qe in the same pH range. The Fe(3+)-grafting increased the zeta potential of raw clinoptilolite, leading to a higher adsorption capacity compared to that of unfunctionalized adsorbent. Also, temperature change was found to have a significant effect on the adsorption process. PMID:24413045

  4. Experimental study of neptunyl adsorption onto Bacillus subtilis

    NASA Astrophysics Data System (ADS)

    Gorman-Lewis, D.; Fein, J. B.; Soderholm, L.; Jensen, M. P.; Chiang, M.-H.

    2005-10-01

    The subsurface mobility of Np is difficult to predict in part due to uncertainties associated with its sorption behavior in geologic systems. In this study, we measured Np adsorption onto a common gram-positive soil bacterium, Bacillus subtilis. We performed batch adsorption experiments with Np(V) solutions as a function of pH, from 2.5 to 8, as a function of total Np concentration from 1.29 × 10 -5 M to 2.57 × 10 -4 M, and as a function of ionic strength from 0.001 to 0.5 M NaClO 4. Under most pH conditions, Np adsorption is reversible and exhibits an inverse relationship with ionic strength, with adsorption increasing with increasing pH. At low pH in the 0.1 M ionic strength systems, we observed irreversible adsorption, which is consistent with reduction of Np(V) to Np(IV). We model the adsorption reaction using a nonelectrostatic surface complexation approach to yield ionic strength dependent NpO 2+-bacterial surface stability constants. The data require two bacterial surface complexation reactions to account for the observed adsorption behavior: R-L 1- + NpO 2+ ↔ R-L 1-NpO 2° and R-L 2- + NpO 2+ ↔ R-L 2-NpO 2°, where R represents the bacterium to which each functional group is attached, and L 1 and L 2 represent the first and second of four discrete site types on the bacterial surface. Stability constants (log K values) for the L 1 and L 2 reactions in the 0.001 M system are 2.3 ± 0.3 and 2.3 ± 0.2, and in the 0.1 M system the values are 1.7 ± 0.2 and 1.6 ± 0.2, respectively. The calculated neptunyl-bacterial surface stability constants are not consistent with values predicted using the linear free energy correlation approach from Fein et al. (2001), suggesting that possible unfavorable steric interactions and the low charge of NpO 2+ affects Np-bacterial adsorption.

  5. The interaction of hydrazine with an Rh(1 1 1) surface as a model for adsorption to rhodium nanoparticles: A dispersion-corrected DFT study

    NASA Astrophysics Data System (ADS)

    He, Yan Bin; Jia, Jian Feng; Wu, Hai Shun

    2015-02-01

    In recent years, metal nanoparticles were found to be excellent catalysts for hydrogen generation from hydrazine for chemical hydrogen storage. In order to gain a better understanding of these catalytic systems, we have simulated the adsorption of hydrazine on rhodium nanoparticles surfaces by density functional theory (DFT) calculations with dispersion correction, DFT-D3 in the method of Grimme. The rhodium nanoparticles were modeled by the Rh(1 1 1) surface, in addition, the adsorptions at corners and edges sites of nanoparticles were considered by using rhodium adatoms on the surfaces. The calculations showed that hydrazine binds most strongly to the edge of nanoparticle with adsorption energy of -2.48 eV, where the hydrazine bridges adatoms of edge with the molecule twisted to avoid a cis structure; similar adsorption energy was found at the corner of nanoparticle, where the hydrazine bridges corner atom and surface atom with gauche configuration. However, we found that inclusion of the dispersion correction results in significant enhancement of molecule-substrate binding, thereby increasing the adsorption energy, especially the adsorption to the Rh(1 1 1) surface. The results demonstrate that the surface structure is a key factor to determine the thermodynamics of adsorption, with low coordinated atoms which providing sites of strong adsorption from the surface.

  6. Relationship Between Liquor Yield, Plant Capacity Increases, and Energy Savings in Alumina Refining

    NASA Astrophysics Data System (ADS)

    Ter Weer, Peter-Hans

    2014-09-01

    The mechanisms of alumina trihydrate precipitation and controlling parameters, and the methods and technologies affecting liquor yield/productivity in alumina refining, have been described in several publications [e.g., Refs. Alamdari et al. ( Light Metals 1998, pp. 133-137, 1998), Moretto and Power ( Proc. 1990 Alumina Quality Workshop, Perth, Australia, pp. 154-165, 1990)]. However, the relationship between increasing liquor yield, on the one hand, and plant production capacity increases and related energy savings, on the other, has been under-emphasized. This article addresses this issue and provides estimates of plant production capacity increases and steam and power energy savings as a function of precipitation yield increases resulting from the implementation of plant adaptations. Conclusions are that increasing precipitation yield in an alumina refinery results overall in a significant improvement of project economics and interestingly improves a refinery's direct and indirect environmental performance, thus, addressing two of the three "pillars" of sustainable development (economic, environmental, and social).

  7. Increasing recoverable energy storage in electroceramic capacitors using ``dead-layer'' engineering

    NASA Astrophysics Data System (ADS)

    McMillen, M.; Douglas, A. M.; Correia, T. M.; Weaver, P. M.; Cain, M. G.; Gregg, J. M.

    2012-12-01

    The manner in which ultrathin films of alumina, deposited at the dielectric-electrode interface, affect the recoverable energy density associated with (BiFeO3)0.6-(SrTiO3)0.4 (BFST) thin film capacitors has been characterised. Approximately 6 nm of alumina on 400 nm of BFST increases the maximum recoverable energy of the system by around 30% from ˜13 Jcc-1 to ˜17 Jcc-1. Essentially, the alumina acts in the same way as a naturally present parasitic "dead-layer," distorting the polarisation-field response such that the ultimate polarisation associated with the BFST is pushed to higher values of electric field. The work acts as a proof-of-principle to illustrate how the design of artificial interfacial dielectric "dead-layers" can increase energy densities in simple dielectric capacitors, allowing them to compete more generally with other energy storage technologies.

  8. Adsorption of Antibiotics on Graphene and Biochar in Aqueous Solutions Induced by π-π Interactions.

    PubMed

    Peng, Bingquan; Chen, Liang; Que, Chenjing; Yang, Ke; Deng, Fei; Deng, Xiaoyong; Shi, Guosheng; Xu, Gang; Wu, Minghong

    2016-01-01

    The use of carbon based materials on the removal of antibiotics with high concentrations has been well studied, however the effect of this removal method is not clear on the actual concentration of environments, such as the hospital wastewater, sewage treatment plants and aquaculture wastewater. In this study, experimental studies on the adsorption of 7 antibiotics in environmental concentration of aqueous solutions by carbon based materials have been observed. Three kinds of carbon materials have shown very fast adsorption to antibiotics by liquid chromatography-tandem mass spectrometry (LC-MS-MS) detection, and the highest removal efficiency of antibiotics could reach to 100% within the range of detection limit. Surprisedly, the adsorption rate of graphene with small specific surface area was stronger than other two biochar, and adsorption rate of the two biochar which have approximate specific surface and different carbonization degree, was significantly different. The key point to the present observation were the π-π interactions between aromatic rings on adsorbed substance and carbon based materials by confocal laser scanning microscope observation. Moreover, adsorption energy markedly increased with increasing number of the π rings by using the density functional theory (DFT), showing the particular importance of π-π interactions in the adsorption process. PMID:27534975

  9. Adsorption of Antibiotics on Graphene and Biochar in Aqueous Solutions Induced by π-π Interactions

    PubMed Central

    Peng, Bingquan; Chen, Liang; Que, Chenjing; Yang, Ke; Deng, Fei; Deng, Xiaoyong; Shi, Guosheng; Xu, Gang; Wu, Minghong

    2016-01-01

    The use of carbon based materials on the removal of antibiotics with high concentrations has been well studied, however the effect of this removal method is not clear on the actual concentration of environments, such as the hospital wastewater, sewage treatment plants and aquaculture wastewater. In this study, experimental studies on the adsorption of 7 antibiotics in environmental concentration of aqueous solutions by carbon based materials have been observed. Three kinds of carbon materials have shown very fast adsorption to antibiotics by liquid chromatography–tandem mass spectrometry (LC-MS-MS) detection, and the highest removal efficiency of antibiotics could reach to 100% within the range of detection limit. Surprisedly, the adsorption rate of graphene with small specific surface area was stronger than other two biochar, and adsorption rate of the two biochar which have approximate specific surface and different carbonization degree, was significantly different. The key point to the present observation were the π-π interactions between aromatic rings on adsorbed substance and carbon based materials by confocal laser scanning microscope observation. Moreover, adsorption energy markedly increased with increasing number of the π rings by using the density functional theory (DFT), showing the particular importance of π-π interactions in the adsorption process. PMID:27534975

  10. Effective adsorption of phosphate from wastewaters by big composite pellets made of reduced steel slag and iron ore concentrate.

    PubMed

    Wang, Hongjuan; Shen, Shaobo; Liu, Longhui; Ji, Yilong; Wang, Fuming

    2015-01-01

    In order to remove phosphate from wastewater, a large plastic adsorption column filled with big phosphate-adsorbing pellets with diameters of 10 mm, heated by electromagnetic induction coils, was conceived. It was found that the prepared big pellets, which were made of reduced steel slag and iron ore concentrate, contain magnetic Fe and Fe3O4. The thermodynamics and kinetics of adsorption of phosphate from synthetic wastewaters on the pellets were studied in this work. The phosphate adsorption on the pellets followed three models of Freundlich, Langmuir and Dubinin-Kaganer-Radushkevick. The maximum phosphate adsorption capacity Qmax of the pellets were 2.46, 2.74 and 2.77 mg/g for the three temperatures of 20°C, 30°C and 40°C, respectively, based on the Langmuir model. The apparent adsorption energies were -12.9 kJ/mol for the three temperatures. It implied that ion exchange was the main mechanism involved in the adsorption processes. The adsorbed phosphate existed on the pellet surface mainly in the form of Fe3(PO4)2. A reduction pre-treatment of the pellet precursor with H2 greatly enhanced pellet adsorption for phosphate. The adsorption kinetics is better represented by a pseudo-first-order model. The adsorbed phosphate amounts were similar for both real and synthetic wastewaters under similar adsorption conditions. The percentage of adsorbed phosphate for a real wastewater increased with increasing pellet concentration and reached 99.2% at a pellet concentration of 64 (g/L). Some specific phosphate adsorption mechanisms for the pellets were revealed and the pellets showed the potential to efficiently adsorb phosphate from a huge amount of real wastewaters in an industrial scale. PMID:26038973

  11. Atomic and Molecular Adsorption on Re(0001)

    SciTech Connect

    Hahn, Konstanze; Mavrikakis, Manos

    2014-02-01

    Using periodic, self-consistent density functional theory calculations, the adsorption of several atomic (H, S, N, O and C) and molecular (CO2, N2, NH3, HCN, CO and NO) species and molecular fragments (NH2, NH, CN, CNH2, HNO, NOH, CH3, CH2, CH and OH) on the (0001) facet of rhenium at a coverage of 0.25 ML has been studied. Preferred binding sites with their corresponding binding energy and deformation energy of the surface, as well as an estimated diffusion barrier of each species have been determined. Atomic species and molecular fragments tend to bind to threefold sites, whereas molecular species tend to bind to top sites. The binding strength, with respect to the corresponding gas phase species and in increasing order for all species studied, is: CO2 < N2 < NH3 < CO < CH3 < HCN < NO < H < NH2 < OH < CH2 < CNH2 < CN < HNO < NH < NOH < S < N < O < CH < C. The vibrational frequencies of all species in their most energetically favorable adsorbed configuration have been calculated. Finally, the thermochemistry of adsorption and decomposition of NO, NO + H, NH3, N2, CO2, CO and CH4 on Re(0001) has been analyzed.

  12. On Increasing Network Lifetime in Body Area Networks Using Global Routing with Energy Consumption Balancing

    PubMed Central

    Tsouri, Gill R.; Prieto, Alvaro; Argade, Nikhil

    2012-01-01

    Global routing protocols in wireless body area networks are considered. Global routing is augmented with a novel link cost function designed to balance energy consumption across the network. The result is a substantial increase in network lifetime at the expense of a marginal increase in energy per bit. Network maintenance requirements are reduced as well, since balancing energy consumption means all batteries need to be serviced at the same time and less frequently. The proposed routing protocol is evaluated using a hardware experimental setup comprising multiple nodes and an access point. The setup is used to assess network architectures, including an on-body access point and an off-body access point with varying number of antennas. Real-time experiments are conducted in indoor environments to assess performance gains. In addition, the setup is used to record channel attenuation data which are then processed in extensive computer simulations providing insight on the effect of protocol parameters on performance. Results demonstrate efficient balancing of energy consumption across all nodes, an average increase of up to 40% in network lifetime corresponding to a modest average increase of 0.4 dB in energy per bit, and a cutoff effect on required transmission power to achieve reliable connectivity. PMID:23201987

  13. Method and apparatus for thermal swing adsorption and thermally-enhanced pressure swing adsorption

    DOEpatents

    Wegeng, Robert S.; Rassat, Scot D.; TeGrotenhuis, Ward E.; Drost, Kevin; Vishwanathan, Vilayanur V.

    2004-06-08

    The present invention provides compact adsorption systems that are capable of rapid temperature swings and rapid cycling. Novel methods of thermal swing adsorption and thermally-enhanced pressure swing adsorption are also described. In some aspects of the invention, a gas is passed through the adsorbent thus allowing heat exchangers to be very close to all portions of the adsorbent and utilize less space. In another aspect, the adsorption media is selectively heated, thus reducing energy costs. Methods and systems for gas adsorption/desorption having improved energy efficiency with capability of short cycle times are also described. In another aspect, the apparatus or methods utilize heat exchange channels of varying lengths that have volumes controlled to provide equal heat fluxes. Methods of fuel cell startup are also described. Advantages of the invention include the ability to use (typically) 30-100 times less adsorbent compared to conventional systems.

  14. Method for thermal swing adsorption and thermally-enhanced pressure swing adsorption

    DOEpatents

    Wegeng, Robert S.; Rassat, Scot D.; Stenkamp, Victoria S.; TeGrotenhuis, Ward E.; Matson, Dean W.; Drost, M. Kevin; Viswanathan, Vilayanur V.

    2003-10-07

    The present invention provides compact adsorption systems that are capable of rapid temperature swings and rapid cycling. Novel methods of thermal swing adsorption and thermally-enhanced pressure swing adsorption are also described. In some aspects of the invention, a gas is passed through the adsorbent thus allowing heat exchangers to be very close to all portions of the adsorbent and utilize less space. In another aspect, the adsorption media is selectively heated, thus reducing energy costs. Methods and systems for gas adsorption/desorption having improved energy efficiency with capability of short cycle times are also described. Advantages of the invention include the ability to use (typically) 30-100 times less adsorbent compared to conventional systems.

  15. Apparatus for thermal swing adsorption and thermally-enhanced pressure swing adsorption

    DOEpatents

    Wegeng, Robert S.; Rassat, Scot D.; Stenkamp, Victoria S.; TeGrotenhuis, Ward E.; Matson, Dean W.; Drost, M. Kevin; Viswanathan, Vilayanur V.

    2005-12-13

    The present invention provides compact adsorption systems that are capable of rapid temperature swings and rapid cycling. Novel methods of thermal swing adsorption and thermally-enhanced pressure swing adsorption are also described. In some aspects of the invention, a gas is passed through the adsorbent thus allowing heat exchangers to be very close to all portions of the adsorbent and utilize less space. In another aspect, the adsorption media is selectively heated, thus reducing energy costs. Methods and systems for gas adsorption/desorption having improved energy efficiency with capability of short cycle times are also described. Advantages of the invention include the ability to use (typically) 30-100 times less adsorbent compared to conventional systems.

  16. Early cementing does not increase debond energy of grit blasted interfaces.

    PubMed

    Mann, Kenneth A; Damron, Leatha A; Race, Amos; Ayers, David C

    2004-07-01

    A fracture mechanics based approach was used to determine the debond energy or fracture toughness of the stem-cement interface for a variety of conditions. The goals of the study were to determine if early cementing of stems increased the debond energy of grit blasted stem-cement interfaces and if debond energy was dependent on mold type. Early (2 min) and late (6 min) times of cementation were considered for two different grit blasted surface finishes (16 and 60 grit, Ra=5.7 or 2.3 microm). Specimen fabrication was performed using a relatively simple, unconstrained rectangular mold and a mold that more closely simulated in vivo conditions. The rectangular mold was used with all components at room temperature whereas the in vivo simulated mold had a body that resembled the femoral canal in shape and was warmed to body temperature. Early cementing did not increase the debond energy using the in vivo simulated mold. Extensive porosity was found at the interface, and porosity had a strong negative effect on debond energy. When the simpler, rectangular mold was used, early cementing did result in higher debond energies, but few voids were found at the interface. It appears that porosity at the interface was the major factor affecting the debond energy. The results from this study do not support the concept that improved stem-cement interface strength can be obtained by application of the cement while it is in a low viscosity state. PMID:15183440

  17. First-principles study of adsorption of methanethiol on Co(0001)

    NASA Astrophysics Data System (ADS)

    Wang, L. G.; Tsymbal, E. Y.; Jaswal, S. S.

    2004-08-01

    Investigation of the resident site and the adsorption phase structure of thiolates is of fundamental importance for understanding the formation of self-assembled organic monolayers on metal substrate surfaces. In the present study, we have investigated adsorption of methanethiol, CH3SH , on the ferromagnetic Co(0001) surface using density functional theory calculations. We find that the dissociative adsorption of CH3SH forming an adsorbed methylthiolate (CH3S) and an adsorbed H atom is energetically favorable, and that the CH3S molecule adsorbed at the threefold fcc and hcp hollow sites is most stable. The adsorption energy at the bridge site is only ˜0.2eV smaller than that at the threefold hollow site, and the adsorption of CH3S at the atop site is unstable. For the (3×3)R30° , (2×2) and (2×3) adsorptions, we find that the S-C bond tends to be normal to the surface, whereas for the (2×1) adsorption it tilts away from the surface normal direction by ˜40° . The (2×1) adsorption phase is much less stable. The reduction of the adsorption energy with the increasing coverage is attributed to the repulsive interaction between the adsorbates. Our calculations show that the (3×3)R30° structure may form in the process of methylthiolate adsorption on Co(0001) due to its adsorption energy being only 0.1eV lower than that for the (2×2) and (2×3) structures. We find that there is a charge transfer from the substrate surface atoms to the S atoms, and that the S-Co bond is strongly polar. The surface Co atoms bound to S have a magnetic moment of ˜1.66μB , while the surface Co atoms unbound to S have a larger magnetic moment of ˜1.85μB . The S atom in the adsorbed CH3S acquires a magnetic moment of ˜0.08μB .

  18. Kinetic and thermodynamic studies of sulforaphane adsorption on macroporous resin.

    PubMed

    Yuanfeng, Wu; Lei, Zhang; Jianwei, Mao; Shiwang, Liu; Jun, Huang; Yuru, You; Lehe, Mei

    2016-08-15

    The adsorption equilibrium, kinetic and thermodynamic of sulforaphane (SF) adsorption onto macroporous resin in aqueous phase were studied. The SP850 resin was screened as the appropriate resin for SF purification. From the equilibrium studies, the Redlich-Peterson model was found to be the best for description of the adsorption behavior of SF onto SP850 resin, followed by the Freundlich model and the Langmuir model. Batch equilibrium experiments demonstrated that, in the examined temperature range, the equilibrium adsorption capacity of SP850 resin decreased with increasing adsorption temperature. Thermodynamics studies indicated that the adsorption of SF was a physical, exothermic, and spontaneous process. The adsorption kinetics revealed that the pseudo-second-order kinetic model was suitable to characterize the kinetics of adsorption of SF onto SP850. Finally, the intra-particle diffusion model demonstrated that SF diffused quickly into macropores, and that diffusion slowed down in the meso- and micropores. PMID:27391585

  19. Adsorption of cationic surfactants and their effects on the interfacial properties of quartz

    NASA Astrophysics Data System (ADS)

    Jia, Renhe

    This dissertation is primarily concerned with an investigation of the interfacial behavior of natural quartz in aqueous solution where the adsorption of various cationic surfactants is involved. The broad objective of this research was to delineate the mechanisms involved in the adsorption of cationic surfactants using experimental determination of adsorption isotherms, zeta potentials, suspension turbidity, contact angles, induction times, as well as Hallimond tube flotation response. With dodecylpyridinium chloride as the model surfactant, four-region adsorption isotherms were observed and found to correlate well with zeta potential, suspension stability and contact angle measurements. Calculations of adsorption energy showed strong specific adsorption in Region I, probably resulting from H-bonding of the pyridinium headgroup to active sites on the silica. As a result of hemimicelle formation at the solid-liquid interface in Region II, pronounced increases in the adsorption density, zeta potential, and surface hydrophobicity were observed. The stability of quartz suspensions showed a significant drop in this region. In Region III, the zeta potential is reversed and the stability of the suspensions begins to increase again. In this region, the surface hydrophobicity of quartz decreases with further surfactant adsorption, suggesting reverse orientation of the adsorbed surfactant ions. In Region IV, the adsorption isotherm and zeta potential reach a plateau when the surfactant concentration reaches the CMC, and the surface becomes completely hydrophilic. The molecular structure of surfactant ions (chain length, number of hydrocarbon chains and number of headgroups) was found to significantly affect their surface activity. Increasing the hydrocarbon chain length of the surfactant lowers the concentration of surfactant required for minimum suspension stability, as well as redispersion. The adsorption is stronger for surfactants whose structure permits hydrogen bonding

  20. Protein Adsorption in Microengraving Immunoassays

    PubMed Central

    Song, Qing

    2015-01-01

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

  1. Increased monolayer domain size and patterned growth of tungsten disulfide through controlling surface energy of substrates

    NASA Astrophysics Data System (ADS)

    Godin, Kyle; Kang, Kyungnam; Fu, Shichen; Yang, Eui-Hyeok

    2016-08-01

    We report a surface energy-controlled low-pressure chemical vapor deposition growth of WS2 monolayers on SiO2 using pre-growth oxygen plasma treatment of substrates, facilitating increased monolayer surface coverage and patterned growth without lithography. Oxygen plasma treatment of the substrate caused an increase in the average domain size of WS2 monolayers by 78%  ±  2% while having a slight reduction in nucleation density, which translates to increased monolayer surface coverage. This substrate effect on growth was exploited to grow patterned WS2 monolayers by patterned plasma treatment on patterned substrates and by patterned source material with resolutions less than 10 µm. Contact angle-based surface energy measurements revealed a dramatic increase in polar surface energy. A growth model was proposed with lowered activation energies for growth and increased surface diffusion length consistent with the range of results observed. WS2 samples grown with and without oxygen plasma were similar high quality monolayers verified through transmission electron microscopy, selected area electron diffraction, atomic force microscopy, Raman, and photoluminescence measurements. This technique enables the production of large-grain size, patterned WS2 without a post-growth lithography process, thereby providing clean surfaces for device applications.

  2. Increasing the collected energy and reducing the water requirements in salt-gradient solar ponds

    NASA Astrophysics Data System (ADS)

    Suarez, F. I.; Ruskowitz, J. A.; Tyler, S. W.; Childress, A. E.

    2013-12-01

    Salt-gradient solar ponds are low-cost, large-scale solar collectors with integrated storage that can be used as an energy source in many thermal systems. For instance, solar ponds have proven to be a promising solution to drive thermal desalination in arid zones. However, in zones with limited water availability, where evaporation constrains the use of solar ponds in areas with the greatest potential for solar energy development, evaporation losses at the surface of the pond constrain their use. Therefore, evaporation represents a significant challenge for development of these low-cost solar systems in arid settings. In this investigation, different transparent floating elements were tested to suppress evaporation: flat discs, hemispheres, and a continuous cover. Flat discs were the most effective evaporation suppression element. Evaporation decreased from 4.8 to 2.5 mm/day when 88% of the pond was covered with the flat discs. In addition, the highest temperature increased from 34 to 43°C and the heat content increased from 179 to 220 MJ (a 22% increase). Reduced evaporative losses at the surface of the pond resulted in lower conductive losses from the storage zone and increased the collected energy. The magnitude of evaporation reduction observed in this work is important as it allows solar pond operation in locations with limited water supply for replenishment. The increase in stored heat allows more energy to be withdrawn from the pond for use in external applications, which significantly improves the thermal efficiencies of solar ponds.

  3. Increasing dietary palmitic acid decreases fat oxidation and daily energy expenditure123

    PubMed Central

    Bunn, Janice Y; Ugrasbul, Figen

    2005-01-01

    Background Oleic acid (OA) is oxidized more rapidly than is palmitic acid (PA). Objective We hypothesized that changing the dietary intakes of PA and OA would affect fatty acid oxidation and energy expenditure. Design A double-masked trial was conducted in 43 healthy young adults, who, after a 28-d, baseline, solid-food diet (41% of energy as fat, 8.4% as PA, and 13.1% as OA), were randomly assigned to one of two 28-d formula diets: high PA (40% of energy as fat, 16.8% as PA, and 16.4% as OA; n = 21) or high OA (40% of energy as fat, 1.7% as PA, and 31.4% as OA; n = 22). Differences in the change from baseline were evaluated by analysis of covariance. Results In the fed state, the respiratory quotient was lower (P = 0.01) with the high OA (0.86 ± 0.01) than with the high-PA (0.89 ± 0.01) diet, and the rate of fat oxidation was higher (P = 0.03) with the high-OA (0.0008 ± 0.0001) than with the high-PA (0.0005 ± 0.0001 mg · kg fat-free mass−1 · min−1) diet. Resting energy expenditure in the fed and fasting states was not significantly different between groups. Change in daily energy expenditure in the high-OA group (9 ± 60 kcal/d) was significantly different from that in the high-PA group (−214 ±69 kcal/d; P = 0.02 or 0.04 when expressed per fat-free mass). Conclusions Increases in dietary PA decrease fat oxidation and daily energy expenditure, whereas decreases in PA and increases in OA had the opposite effect. Increases in dietary PA may increase the risk of obesity and insulin resistance. PMID:16087974

  4. Removal of phenol from aqueous solutions by adsorption.

    PubMed

    Roostaei, Nadia; Tezel, F Handan

    2004-02-01

    Experiments have been conducted to examine the liquid-phase adsorption of phenol from water by silica gel, HiSiv 3000, activated alumina, activated carbon, Filtrasorb-400, and HiSiv 1000. Experiments were carried out for the analysis of adsorption equilibrium capacities and kinetics. The adsorption isotherm model of the Langmuir-Freundlich type was the best to describe adsorption equilibrium data for phenol for the adsorbents studied. Results of kinetic experiments indicated that HiSiv 1000 had the highest rate of adsorption among the adsorbents studied and therefore more detailed studies were carried out with this adsorbent. The influence of particle size, temperature, and thermal regeneration on adsorption of phenol by HiSiv 1000 was evaluated. From particle size experiments it appeared that adsorption capacity of HiSiv 1000 did not change by changing the particle size, but the rate of adsorption decreased considerably by increasing the particle size. The effect of temperature on adsorption was studied by determining equilibrium isotherms for HiSiv 1000 at 25, 40, and 55 degrees C. The results showed that adsorption capacity decreased with increasing temperature. Thermal regeneration of HiSiv 1000 was performed at 360 degrees C. It was observed that adsorption capacity of HiSiv 1000 did not change after 14 regeneration cycles. Equilibrium experiments showed that the adsorption capacities of activated carbon and Filtrasorb-400 were several times higher than that of HiSiv 1000. PMID:15160741

  5. Effect of cation type, alkyl chain length, adsorbate size on adsorption kinetics and isotherms of bromide ionic liquids from aqueous solutions onto microporous fabric and granulated activated carbons.

    PubMed

    Hassan, Safia; Duclaux, Laurent; Lévêque, Jean-Marc; Reinert, Laurence; Farooq, Amjad; Yasin, Tariq

    2014-11-01

    The adsorption from aqueous solution of imidazolium, pyrrolidinium and pyridinium based bromide ionic liquids (ILs) having different alkyl chain lengths was investigated on two types of microporous activated carbons: a fabric and a granulated one, well characterized in terms of surface chemistry by "Boehm" titrations and pH of point of zero charge measurements and of porosity by N2 adsorption at 77 K and CO2 adsorption at 273 K. The influence of cation type, alkyl chain length and adsorbate size on the adsorption properties was analyzed by studying kinetics and isotherms of eight different ILs using conductivity measurements. Equilibrium studies were carried out at different temperatures in the range [25-55 °C]. The incorporation of ILs on the AC porosity was studied by N2 adsorption-desorption measurements at 77 K. The experimental adsorption isotherms data showed a good correlation with the Langmuir model. Thermodynamic studies indicated that the adsorption of ILs onto activated carbons was an exothermic process, and that the removal efficiency increased with increase in alkyl chain length, due to the increase in hydrophobicity of long chain ILs cations determined with the evolution of the calculated octanol-water constant (Kow). The negative values of free energies indicated that adsorption of ILs with long chain lengths having hydrophobic cations was more spontaneous at the investigated temperatures. PMID:24929502

  6. Efficient removal of cesium from aqueous solution with vermiculite of enhanced adsorption property through surface modification by ethylamine.

    PubMed

    Long, Hang; Wu, Pingxiao; Yang, Lin; Huang, Zhujian; Zhu, Nengwu; Hu, Zhixian

    2014-08-15

    Ethylamine modified vermiculite (Ethyl-VER) with high specific surface area and excellent pore structure was prepared to remove cesium from aqueous solution. The physic-chemical properties of the pristine and modified vermiculite were analyzed by X-ray diffraction (XRD), Fourier-transform infrared (FTIR), specific surface area (BET) and scanning electron microscopy/energy disperse spectroscopy (SEM/EDS). The corroding effect of ethylamine increased the specific surface area of vermiculite from 4.35 to 15.59 m(2) g(-1), and the average pore diameter decreased from 6.8 to 5.34 nm. Batch adsorption experiments were conducted as a function of pH, initial Cs(+) concentration, contact time, coexisting cations (K(+), Na(+), Ca(2+)) and low-molecular-weight organic acids (acetic acid, oxalic acid, citric acid) to illustrate the adsorption behavior. The study found that the adsorption capacity of cesium in aqueous solution was improved from 56.92 to 78.17 mg g(-1) after modification. The formation of micropores and mesopores and the increased surface area played a critical role in the enhancement of cesium adsorption. Kinetic experiments indicated that the adsorption process can be simulated well with a pseudo-second-order model. The presence of cations or low-molecular-weight organic acids inhibited cesium adsorption in different degrees. On the basis of our results, Ethyl-VER with good surface characteristics and high adsorption capacity is a suitable adsorbent for cesium removal from aqueous solution. PMID:24910065

  7. Tail suspension increases energy expenditure independently of the melanocortin system in mice.

    PubMed

    Lew, Pei San; Wong, Davie; Yamaguchi, Takafumi; Leckstrom, Arnold; Schwartz, Jacquie; Dodd, Janice G; Mizuno, Tooru M

    2009-10-01

    Space travelers experience anorexia and body weight loss in a microgravity environment, and microgravity-like situations cause changes in hypothalamic activity. Hypothalamic melanocortins play a critical role in the regulation of metabolism. Therefore, we hypothesized that microgravity affects metabolism through alterations in specific hypothalamic signaling pathways, including melanocortin signaling. To address this hypothesis, the microgravity-like situation was produced by an antiorthostatic tail suspension in wild-type and agouti mice, and the effect of tail suspension on energy expenditure and hypothalamic gene expression was examined. Energy expenditure was measured using indirect calorimetry before and during the tail suspension protocol. Hypothalamic tissues were collected for gene expression analysis at the end of the 3 h tail suspension period. Tail suspension significantly increased oxygen consumption, carbon dioxide production, and heat production in wild-type mice. Tail suspension-induced increases in energy expenditure were not attenuated in agouti mice. Although tail suspension did not alter hypothalamic proopiomelanocortin (POMC) and agouti-related protein (AGRP) mRNA levels, it significantly increased hypothalamic interleukin 6 (Il-6) mRNA levels. These data are consistent with the hypothesis that microgravity increases energy expenditure and suggest that these effects are mediated through hypothalamic signaling pathways that are independent of melanocortins, but possibly used by Il-6. PMID:20052010

  8. The impact of forecasted energy price increases on low-income consumers

    SciTech Connect

    Eisenberg, Joel F.

    2005-10-31

    The Department of Energy’s Energy Information Administration (EIA) recently released its short term forecast for residential energy prices for the winter of 2005-2006. The forecast indicates significant increases in fuel costs, particularly for natural gas, propane, and home heating oil, for the year ahead. In the following analysis, the Oak Ridge National Laboratory has integrated the EIA price projections with the Residential Energy Consumption Survey (RECS) for 2001 in order to project the impact of these price increases on the nation’s low-income households by primary heating fuel type, nationally and by Census Region. The statistics are intended for the use of policymakers in the Department of Energy’s Weatherization Assistance Program and elsewhere who are trying to gauge the nature and severity of the problems that will be faced by eligible low-income households during the 2006 fiscal year.

  9. Vagus Nerve Stimulation Increases Energy Expenditure: Relation to Brown Adipose Tissue Activity

    PubMed Central

    Vijgen, Guy H. E. J.; Bouvy, Nicole D.; Leenen, Loes; Rijkers, Kim; Cornips, Erwin; Majoie, Marian; Brans, Boudewijn; van Marken Lichtenbelt, Wouter D.

    2013-01-01

    Background Human brown adipose tissue (BAT) activity is inversely related to obesity and positively related to energy expenditure. BAT is highly innervated and it is suggested the vagus nerve mediates peripheral signals to the central nervous system, there connecting to sympathetic nerves that innervate BAT. Vagus nerve stimulation (VNS) is used for refractory epilepsy, but is also reported to generate weight loss. We hypothesize VNS increases energy expenditure by activating BAT. Methods and Findings Fifteen patients with stable VNS therapy (age: 45±10yrs; body mass index; 25.2±3.5 kg/m2) were included between January 2011 and June 2012. Ten subjects were measured twice, once with active and once with inactivated VNS. Five other subjects were measured twice, once with active VNS at room temperature and once with active VNS under cold exposure in order to determine maximal cold-induced BAT activity. BAT activity was assessed by 18-Fluoro-Deoxy-Glucose-Positron-Emission-Tomography-and-Computed-Tomography. Basal metabolic rate (BMR) was significantly higher when VNS was turned on (mean change; +2.2%). Mean BAT activity was not significantly different between active VNS and inactive VNS (BAT SUVMean; 0.55±0.25 versus 0.67±0.46, P = 0.619). However, the change in energy expenditure upon VNS intervention (On-Off) was significantly correlated to the change in BAT activity (r = 0.935, P<0.001). Conclusions VNS significantly increases energy expenditure. The observed change in energy expenditure was significantly related to the change in BAT activity. This suggests a role for BAT in the VNS increase in energy expenditure. Chronic VNS may have a beneficial effect on the human energy balance that has potential application for weight management therapy. Trial Registration The study was registered in the Clinical Trial Register under the ClinicalTrials.gov Identifier NCT01491282. PMID:24194874

  10. Increased energy and nutrient intake during training and competition improves elite triathletes' endurance performance.

    PubMed

    Frentsos, J A; Baer, J T

    1997-03-01

    Dietary habits were evaluated in 6 elite triathletes (4 male, 2 female). Analysis of 7-day diet records showed mean daily energy and carbohydrate intake to be insufficient to support estimated requirements. Mean intakes of vitamins and most minerals exceeded the Recommended Dietary Allowances (RDAs) except zinc chromium, which did not meet 66% of recommended amounts. Individualized nutrition intervention using the Diabetic Food Exchange System to support performance during training and competition was provided. To improve dietary intake, subjects consumed fortified nutrition supplements (Reliv, Inc.) before and after daily training. Follow-up 7-day diet records showed that average energy intake and percentage of energy from carbohydrate increased, as did intakes of zinc and chromium. Triathletes' performance in a short course triathlon was improved compared to a similar competition completed prior to the nutrition intervention. Following the intervention, triathletes were able to meet recommended daily energy, macronutrient, and micronutrient intakes and improve endurance performance. PMID:9063765

  11. Transient energy deficit induced by exercise increases 24-h fat oxidation in young trained men.

    PubMed

    Iwayama, Kaito; Kawabuchi, Ryosuke; Park, Insung; Kurihara, Reiko; Kobayashi, Masashi; Hibi, Masanobu; Oishi, Sachiko; Yasunaga, Koichi; Ogata, Hitomi; Nabekura, Yoshiharu; Tokuyama, Kumpei

    2015-01-01

    Whole body fat oxidation increases during exercise. However, 24-h fat oxidation on a day with exercise often remains similar to that of sedentary day, when energy intake is increased to achieve an energy-balanced condition. The present study aimed to examine a possibility that time of the day when exercise is performed makes differences in 24-h fat oxidation. As a potential mechanism of exercise affecting 24-h fat oxidation, its relation to exercise-induced transient energy deficit was examined. Nine young male endurance athletes underwent three trials of indirect calorimetry using a metabolic chamber, in which they performed a session of 100 min of exercise before breakfast (AM), after lunch (PM), or two sessions of 50 min of exercise before breakfast and after lunch (AM/PM) at 65% of maximal oxygen uptake. Experimental meals were designed to achieve individual energy balance. Twenty-four-hour energy expenditure was similar among the trials, but 24-h fat oxidation was 1,142 ± 97, 809 ± 88, and 608 ± 46 kcal/24 h in descending order of its magnitude for AM, AM/PM, and PM, respectively (P < 0.05). Twenty-four-hour carbohydrate oxidation was 2,558 ± 110, 2,374 ± 114, and 2,062 ± 96 kcal/24 h for PM, AM/PM, and AM, respectively. In spite of energy-balanced condition over 24 h, exercise induced a transient energy deficit, the magnitude of which was negatively correlated with 24-h fat oxidation (r = -0.72, P < 0.01). Similarly, transient carbohydrate deficit after exercise was negatively correlated with 24-h fat oxidation (r = -0.40, P < 0.05). The time of the day when exercise is performed affects 24-h fat oxidation, and the transient energy/carbohydrate deficit after exercise is implied as a factor affecting 24-h fat oxidation. PMID:25554797

  12. Templated assembly of photoswitches significantly increases the energy-storage capacity of solar thermal fuels

    NASA Astrophysics Data System (ADS)

    Kucharski, Timothy J.; Ferralis, Nicola; Kolpak, Alexie M.; Zheng, Jennie O.; Nocera, Daniel G.; Grossman, Jeffrey C.

    2014-05-01

    Large-scale utilization of solar-energy resources will require considerable advances in energy-storage technologies to meet ever-increasing global energy demands. Other than liquid fuels, existing energy-storage materials do not provide the requisite combination of high energy density, high stability, easy handling, transportability and low cost. New hybrid solar thermal fuels, composed of photoswitchable molecules on rigid, low-mass nanostructures, transcend the physical limitations of molecular solar thermal fuels by introducing local sterically constrained environments in which interactions between chromophores can be tuned. We demonstrate this principle of a hybrid solar thermal fuel using azobenzene-functionalized carbon nanotubes. We show that, on composite bundling, the amount of energy stored per azobenzene more than doubles from 58 to 120 kJ mol-1, and the material also maintains robust cyclability and stability. Our results demonstrate that solar thermal fuels composed of molecule-nanostructure hybrids can exhibit significantly enhanced energy-storage capabilities through the generation of template-enforced steric strain.

  13. Templated assembly of photoswitches significantly increases the energy-storage capacity of solar thermal fuels.

    PubMed

    Kucharski, Timothy J; Ferralis, Nicola; Kolpak, Alexie M; Zheng, Jennie O; Nocera, Daniel G; Grossman, Jeffrey C

    2014-05-01

    Large-scale utilization of solar-energy resources will require considerable advances in energy-storage technologies to meet ever-increasing global energy demands. Other than liquid fuels, existing energy-storage materials do not provide the requisite combination of high energy density, high stability, easy handling, transportability and low cost. New hybrid solar thermal fuels, composed of photoswitchable molecules on rigid, low-mass nanostructures, transcend the physical limitations of molecular solar thermal fuels by introducing local sterically constrained environments in which interactions between chromophores can be tuned. We demonstrate this principle of a hybrid solar thermal fuel using azobenzene-functionalized carbon nanotubes. We show that, on composite bundling, the amount of energy stored per azobenzene more than doubles from 58 to 120 kJ mol(-1), and the material also maintains robust cyclability and stability. Our results demonstrate that solar thermal fuels composed of molecule-nanostructure hybrids can exhibit significantly enhanced energy-storage capabilities through the generation of template-enforced steric strain. PMID:24755597

  14. Increasing the energy conservation awareness using the influential power of a lottery system

    NASA Astrophysics Data System (ADS)

    Nayak, Amruta Vijay

    This thesis presents an influence maximization-driven approach to promoting energy conservation awareness, with the objective to generate a competitive environment for energy consumption supervision. As consumers are typically reluctant to invest their time and effort in the activities beyond their business, an incentive-based distribution strategy is proposed to encourage consumers to actively take part in energy conservation. The key idea of the thesis lies in leveraging the consumer instincts as a driving factor for spreading positive social influence, via a smart lottery program. In the proposed framework, saving energy automatically increases the consumers' chances of winning the lottery, thereby motivating them to save more, while the smart winner selection will maximize the word-of-mouth effect of the program. The thesis collects and organizes a large body of literature in support of the claim that the spread of awareness in a social network can play a key role in the emergence of energy conscious behavior. It also reports on the findings of a survey conducted to determine the present day consumer perspective toward energy conservation and the level of influence required to motivate them to conserve more energy. Finally, a mathematical model for smart lottery winner selection is presented, and insightful observations are made concerning the properties of optimal solutions to tractable, small problem instances.

  15. Templated assembly of photoswitches significantly increases the energy-storage capacity of solar thermal fuels

    SciTech Connect

    Kucharski, TJ; Ferralis, N; Kolpak, AM; Zheng, JO; Nocera, DG; Grossman, JC

    2014-04-13

    Large-scale utilization of solar-energy resources will require considerable advances in energy-storage technologies to meet ever-increasing global energy demands. Other than liquid fuels, existing energy-storage materials do not provide the requisite combination of high energy density, high stability, easy handling, transportability and low cost. New hybrid solar thermal fuels, composed of photoswitchable molecules on rigid, low-mass nanostructures, transcend the physical limitations of molecular solar thermal fuels by introducing local sterically constrained environments in which interactions between chromophores can be tuned. We demonstrate this principle of a hybrid solar thermal fuel using azobenzene-functionalized carbon nanotubes. We show that, on composite bundling, the amount of energy stored per azobenzene more than doubles from 58 to 120 kJ mol(-1), and the material also maintains robust cyclability and stability. Our results demonstrate that solar thermal fuels composed of molecule-nanostructure hybrids can exhibit significantly enhanced energy-storage capabilities through the generation of template-enforced steric strain.

  16. [Adsorption characteristics of the antibiotic sulfanilamide onto rice husk ash].

    PubMed

    Ji, Ying-Xue; Wang, Feng-He; Zhang, Fan; Zhang, Yan-Hong; Wang, Guo-Xiang; Gu, Zhong-Zhu

    2013-10-01

    Under different conditions of initial rice husk ash (RHA) dosage, oscillating temperature, oscillating frequency and solution pH, the adsorption characteristics of sulfanilamide on RHA with the change of time and its adsorption kinetics were investigated. RHA was characterized by SEM and FTIR before and after sulfanilamide adsorption. The results indicated that the adsorption characteristics of sulfanilamide on RHA was influenced by RHA dosage, oscillating temperature, oscillating frequency and solution pH. Within the RHA dosing range (0. 1-2.0 g.L-1) in this experiment, the optimal temperature for the adsorption was 25C , and with the increase of RHA dosage, the removal efficiency of sulfanilamide increased, the time required to reach adsorption equilibrium was shortened and the adsorptive quantity of sulfanilamide by per unit mass of RHA decreased. A high oscillating frequency was used to ensure the adsorption effect when the RHA concentration was high. Strong acidic and strong alkaline conditions were conducive to the adsorption of sulfanilamide. The analysis of adsorption dynamics showed that for the adsorption process with high RHA dosage ( >or= 1.0 g.L-1), the pseudo-second-order model fitted the adsorption behavior well, and the process was controlled by physical and chemical adsorption. Intraparticle diffusion model showed that the adsorption process was controlled by both membrane diffusion and internal diffusion, and the influence of the former became more obvious with the increase of the adsorbent concentration. Both the SEM and FTIR spectra proved the effective adsorption of sulfanilamide by RHA. PMID:24364310

  17. A Single Oral Administration of Theaflavins Increases Energy Expenditure and the Expression of Metabolic Genes

    PubMed Central

    Kudo, Naoto; Arai, Yasunori; Suhara, Yoshitomo; Ishii, Takeshi; Nakayama, Tsutomu; Osakabe, Naomi

    2015-01-01

    Theaflavins are polyphenols found in black tea, whose physiological activities are not well understood. This study on mice evaluated the influence of a single oral administration of theaflavins on energy metabolism by monitoring the initial metabolic changess in skeletal muscle and brown adipose tissue (BAT). Oxygen consumption (VO2) and energy expenditure (EE) were increased significantly in mice treated with theaflavin rich fraction (TF) compared with the group administered vehicle alone. There was no difference in locomotor activity. Fasting mice were euthanized under anesthesia before and 2 and 5, 20-hr after treatment with TF or vehicle. The mRNA levels of uncoupling protein-1 (UCP-1) and peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) in BAT were increased significantly 2-hr after administration ofTF. The levels of UCP-3 and PGC-1α in the gastrocnemius muscle were increased significantly 2 and 5-hr after administration of TF. The concentration of phosphorylated AMP-activated protein kinase (AMPK) 1α was also increased significantly in the gastrocnemius 2 and 5-hr after treatment with TF. These results indicate that TF significantly enhances systemic energy expenditure, as evidenced by an increase in expression of metabolic genes. PMID:26375960

  18. A Single Oral Administration of Theaflavins Increases Energy Expenditure and the Expression of Metabolic Genes.

    PubMed

    Kudo, Naoto; Arai, Yasunori; Suhara, Yoshitomo; Ishii, Takeshi; Nakayama, Tsutomu; Osakabe, Naomi

    2015-01-01

    Theaflavins are polyphenols found in black tea, whose physiological activities are not well understood. This study on mice evaluated the influence of a single oral administration of theaflavins on energy metabolism by monitoring the initial metabolic changess in skeletal muscle and brown adipose tissue (BAT). Oxygen consumption (VO2) and energy expenditure (EE) were increased significantly in mice treated with theaflavin rich fraction (TF) compared with the group administered vehicle alone. There was no difference in locomotor activity. Fasting mice were euthanized under anesthesia before and 2 and 5, 20-hr after treatment with TF or vehicle. The mRNA levels of uncoupling protein-1 (UCP-1) and peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) in BAT were increased significantly 2-hr after administration ofTF. The levels of UCP-3 and PGC-1α in the gastrocnemius muscle were increased significantly 2 and 5-hr after administration of TF. The concentration of phosphorylated AMP-activated protein kinase (AMPK) 1α was also increased significantly in the gastrocnemius 2 and 5-hr after treatment with TF. These results indicate that TF significantly enhances systemic energy expenditure, as evidenced by an increase in expression of metabolic genes. PMID:26375960

  19. Increasing the solar photovoltaic energy capture on sunny and cloudy days

    SciTech Connect

    Kelly, Nelson A.; Gibson, Thomas L.

    2011-01-15

    This report analyzes an extensive set of measurements of the solar irradiance made using four identical solar arrays and associated solar sensors (collectively referred to as solar collectors) with different tilt angles relative to the earth's surface, and thus the position of the sun, in order to determine an optimal tracking algorithm for capturing solar radiation. The study included a variety of ambient conditions including different seasons and both cloudy and cloud-free conditions. One set of solar collectors was always approximately pointed directly toward the sun (DTS) for a period around solar noon. These solar collectors thus captured the direct beam component of the solar radiation that predominates on sunny days. We found that on sunny days, solar collectors with a DTS configuration captured more solar energy in accordance with the well-known cosine dependence for the response of a flat-surfaced solar collector to the angle of incidence with direct beam radiation. In particular, a DTS orientation was found to capture up to twice as much solar energy as a horizontal (H) orientation in which the array is tilted toward the zenith. Another set of solar collectors always had an H orientation, and this best captured the diffuse component of the solar radiation that predominates on cloudy days. The dependence of the H/DTS ratio on the solar-collector tilt angle was in approximate agreement with the Isotropic Diffuse Model derived for heavily overcast conditions. During cloudy periods, we found that an H configuration increased the solar energy capture by nearly 40% compared to a DTS configuration during the same period, and we estimate the solar energy increase of an H configuration over a system that tracks the obscured solar disk could reach 50% over a whole heavily-overcast day. On an annual basis the increase is predicted to be much less, typically only about 1%, because the contribution of cloudy days to the total annual solar energy captured by a

  20. Relative effects of submersion and increased pressure on respiratory mechanics, work, and energy cost of breathing.

    PubMed

    Held, Heather E; Pendergast, David R

    2013-03-01

    Submersion and increased pressure (depth) characterize the diving environment and may independently increase demand on the respiratory system. To quantify changes in respiratory mechanics, this study employed a unique protocol and techniques to measure, in a hyperbaric chamber, inspiratory and expiratory alveolar pressures (interrupter technique), inspiratory and expiratory resistance in the airways (RawI and RawE, esophageal balloon technique), nitric oxide elimination (thought to correlate with Raw), inspiratory and expiratory mechanical power of breathing, and the total energy cost of ventilation. Eight healthy adult men underwent experiments at 1, 2.7, and 4.6 atmospheres absolute (ATA) in dry and fully submersed conditions. Subjects rested, cycled on an ergometer at 100 W, and rested while voluntarily matching their ventilation to their own exercise hyperpnea (isocapnic simulated exercise ventilation). During isocapnic simulated exercise ventilation, increased O2 uptake (above rest values) resulted from increased expired ventilation. RawI decreased with submersion (mean 43% during rest and 20% during exercise) but increased from 1 to 4.6 ATA (19% during rest and 75% during exercise), as did RawE (53% decrease with submersion during rest and 10% during exercise; 9% increase from 1 to 4.6 ATA during rest and 66% during exercise). Nitric oxide elimination did not correlate with Raw. Depth increased inspiratory mechanical power of breathing during rest (40%) and exercise (20%). Expiratory mechanical power of breathing was largely unchanged. These results suggest that the diving environment affects ventilatory mechanics primarily by increasing Raw, secondary to increased gas density. This necessitates increased alveolar pressure and increases the work and energy cost of breathing as the diver descends. These findings can inform physician assessment of diver fitness and the pulmonary risks of hyperbaric O2 therapy. PMID:23305982

  1. Adsorption and excess fission xenon

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  2. Short sleep duration increases energy intakes but does not change energy expenditure in normal-weight individuals123

    PubMed Central

    St-Onge, Marie-Pierre; Roberts, Amy L; Chen, Jinya; Kelleman, Michael; O'Keeffe, Majella; RoyChoudhury, Arindam; Jones, Peter JH

    2011-01-01

    Background: Evidence suggests a relation between short sleep duration and obesity. Objective: We assessed energy balance during periods of short and habitual sleep in normal-weight men and women. Design: Fifteen men and 15 women aged 30–49 y with a body mass index (in kg/m2) of 22–26, who regularly slept 7–9 h/night, were recruited to participate in this crossover inpatient study. All participants were studied under short (4 h/night) and habitual (9 h/night) sleep conditions, in random order, for 5 nights each. Food intake was measured on day 5, and energy expenditure was measured with the doubly labeled water method over each period. Results: Participants consumed more energy on day 5 during short sleep (2813.6 ± 593.0 kcal) than during habitual sleep (2517.7 ± 593.0 kcal; P = 0.023). This effect was mostly due to increased consumption of fat (20.7 ± 37.4 g; P = 0.01), notably saturated fat (8.7 ± 20.4 g; P = 0.038), during short sleep. Resting metabolic rate (short sleep: 1455.4 ± 129.0 kcal/d; habitual sleep: 1486.5 ± 129.5 kcal/d; P = 0.136) and total energy expenditure (short sleep: 2589.2 ± 526.5 kcal/d; habitual sleep: 2611.1 ± 529.0 kcal/d; P = 0.832) did not differ significantly between sleep phases. Conclusions: Our data show that a reduction in sleep increases energy and fat intakes, which may explain the associations observed between sleep and obesity. If sustained, as observed, and not compensated by increased energy expenditure, the dietary intakes of individuals undergoing short sleep predispose to obesity. This trial is registered at clinicaltrials.gov as NCT00935402. PMID:21715510

  3. Molecular dynamics simulation on adsorption of pyrene-polyethylene onto ultrathin single-walled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Cai, Lu; Lv, Wenzhen; Zhu, Hong; Xu, Qun

    2016-07-01

    The mechanism of the adsorption of pyrene-polyethylene (Py-PE) onto ultrathin single-walled carbon nanotube (SWNT) was studied by using all-atom molecular dynamics (MD) simulations. We found that solvent polarity and pyrene group are two critical factors in the Py-PE decoration on ultrathin SWNT. Combined MD simulations with free energy calculations, our results indicate that larger solvent polarity can decrease the contribution of conformation entropy, but contributes little to the interaction energy, moreover, larger SWNT diameter can decrease the contribution of conformation entropy but lead to the increasing of the interaction energy. In polar organic solvent (N, N-Dimethylacetamide), the pyrene group plays a key role in the adsorption of Py-PE onto ultrathin SWNT, not only facilitates the spontaneous adsorption of Py-PE onto ultrathin SWNT, but also helps to form compact structure between themselves in the final adsorption states. While in aqueous solution, pyrene group no longer works as an anchor, but still affects a lot to the final adsorption conformation. Our present work provides detailed theoretical clue to understand the noncovalent interaction between aromatic segment appended polymer and ultrathin SWNT, and helps to explore the potential application of ultrathin SWNT in the fields of hybrid material, biomedical and electronic materials.

  4. Study on adsorption and desorption of ammonia on graphene.

    PubMed

    Zhang, Zhengwei; Zhang, Xinfang; Luo, Wei; Yang, Hang; He, Yanlan; Liu, Yixing; Zhang, Xueao; Peng, Gang

    2015-12-01

    The gas sensor based on pristine graphene with conductance type was studied theoretically and experimentally. The time response of conductance measurements showed a quickly and largely increased conductivity when the sensor was exposed to ammonia gas produced by a bubble system of ammonia water. However, the desorption process in vacuum took more than 1 h which indicated that there was a larger number of transferred carriers and a strong adsorption force between ammonia and graphene. The desorption time could be greatly shortened down to about 2 min by adding the flow of water-vapor-enriched air at the beginning of the recovery stage which had been confirmed as a rapid and high-efficiency desorption process. Moreover, the optimum geometries, adsorption energies, and the charge transfer number of the composite systems were studied with first-principle calculations. However, the theoretical results showed that the adsorption energy between NH3 and graphene was too small to fit for the experimental phenomenon, and there were few charges transferred between graphene and NH3 molecules, which was completely different from the experiment measurement. The adsorption energy between NH4 and graphene increased stage by stage which showed NH4 was a strong donor. The calculation suggested that H2O molecule could help a quick desorption of NH4 from graphene by converting NH4 to NH3 or (NH3)n(H2O)m groups, which was consistent with the experimental results. This study demonstrates that the ammonia gas produced by a bubble system of ammonia water is mainly ammonium groups of NH3 and NH4, and the NH4 moleculars are ideal candidates for the molecular doping of graphene while the interaction between graphene and the NH3 moleculars is weak. PMID:26377212

  5. Study on adsorption and desorption of ammonia on graphene

    NASA Astrophysics Data System (ADS)

    Zhang, Zhengwei; Zhang, Xinfang; Luo, Wei; Yang, Hang; He, Yanlan; Liu, Yixing; Zhang, Xueao; Peng, Gang

    2015-09-01

    The gas sensor based on pristine graphene with conductance type was studied theoretically and experimentally. The time response of conductance measurements showed a quickly and largely increased conductivity when the sensor was exposed to ammonia gas produced by a bubble system of ammonia water. However, the desorption process in vacuum took more than 1 h which indicated that there was a larger number of transferred carriers and a strong adsorption force between ammonia and graphene. The desorption time could be greatly shortened down to about 2 min by adding the flow of water-vapor-enriched air at the beginning of the recovery stage which had been confirmed as a rapid and high-efficiency desorption process. Moreover, the optimum geometries, adsorption energies, and the charge transfer number of the composite systems were studied with first-principle calculations. However, the theoretical results showed that the adsorption energy between NH3 and graphene was too small to fit for the experimental phenomenon, and there were few charges transferred between graphene and NH3 molecules, which was completely different from the experiment measurement. The adsorption energy between NH4 and graphene increased stage by stage which showed NH4 was a strong donor. The calculation suggested that H2O molecule could help a quick desorption of NH4 from graphene by converting NH4 to NH3 or (NH3)n(H2O)m groups, which was consistent with the experimental results. This study demonstrates that the ammonia gas produced by a bubble system of ammonia water is mainly ammonium groups of NH3 and NH4, and the NH4 moleculars are ideal candidates for the molecular doping of graphene while the interaction between graphene and the NH3 moleculars is weak.

  6. Energy intake over 2 days is unaffected by acute sprint interval exercise despite increased appetite and energy expenditure.

    PubMed

    Beaulieu, Kristine; Olver, T Dylan; Abbott, Kolten C; Lemon, Peter W R

    2015-01-01

    A cumulative effect of reduced energy intake, increased oxygen consumption, and/or increased lipid oxidation could explain the fat loss associated with sprint interval exercise training (SIT). This study assessed the effects of acute sprint interval exercise (SIE) on energy intake, subjective appetite, appetite-related peptides, oxygen consumption, and respiratory exchange ratio over 2 days. Eight men (25 ± 3 years, 79.6 ± 9.7 kg, body fat 13% ± 6%; mean ± SD) completed 2 experimental treatments: SIE and recovery (SIEx) and nonexercise control. Each 34-h treatment consisted of 2 consecutive 10-h test days. Between 0800-1800 h, participants remained in the laboratory for 8 breath-by-breath gas collections, 3 buffet-type meals, 14 appetite ratings, and 4 blood samples for appetite-related peptides. Treatment comparisons were made using 2-way repeated measures ANOVA or t tests. An immediate, albeit short-lived (<1 h), postexercise suppression of appetite and increase in peptide YY (PYY) were observed (P < 0.001). However, overall hunger and motivation to eat were greater during SIEx (P < 0.02) without affecting energy intake. Total 34-h oxygen consumption was greater during SIEx (P = 0.04), elicited by the 1491-kJ (22%) greater energy expenditure over the first 24 h (P = 0.01). Despite its effects on oxygen consumption, appetite, and PYY, acute SIE did not affect energy intake. Consequently, if these dietary responses to SIE are sustained with regular SIT, augmentations in oxygen consumption and/or a substrate shift toward increased fat use postexercise are most likely responsible for the observed body fat loss with this type of exercise training. PMID:25494974

  7. Adsorption of copper ions by ion-imprinted simultaneous interpenetrating network hydrogel: Thermodynamics, morphology and mechanism

    NASA Astrophysics Data System (ADS)

    Wang, Jingjing; Ding, Liang; Wei, Jun; Liu, Fang

    2014-06-01

    Cu(II) ion-imprinted hydrogel [Cu(II)-IIH] with interpenetrating polymer network (IPN) structure was prepared and its application to adsorb Cu(II) ions from aqueous solution was studied. The Cu(II)-IIH was prepared by UV-initiated simultaneous free radical/cationic hybrid polymerization. The adsorption capacity of the Cu(II)-IIH increased with the initial pH value of the solution, but decreased as the temperature rose from 303 to 323 K. Thermodynamic parameters such as the Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) for the Cu(II) ions adsorption were evaluated. It was suggested that the adsorption was a spontaneous, exothermic process with further decrease in the degree of freedom at the solid-solution interface due to the negative ΔS° value. The morphology study indicated that the copper adsorption caused significant changes to the hydrogel structure. Finally the adsorption mechanism was studied by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The results indicated that copper adsorption was mainly through interactions with the amide and ether groups.

  8. Adsorption studies on fruits of Gular (Ficus glomerata): removal of Cr(VI) from synthetic wastewater.

    PubMed

    Rao, Rifaqat A K; Rehman, Fouzia

    2010-09-15

    The adsorption of Cr(VI) was studied in batch system using fruits of Ficus glomerata as adsorbent. The effect of temperature, pH, initial Cr(VI) concentration and time was investigated. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) was used to investigate surface morphology and active functional groups present on the adsorbent surface. Thermodynamic parameters like free energy change (DeltaG(0)), enthalpy (DeltaH(0)) and entropy (DeltaS(0)) indicate the spontaneous, endothermic and increased randomness nature of Cr(VI) adsorption. Equilibrium data were fitted well with Langmuir isotherm at 50 degrees C. The magnitude of mean free energy indicates chemical nature of adsorption. The breakthrough and exhaustive capacities were found to be 5 and 23.1 mg g(-1) respectively. The applicability of the adsorbent has been demonstrated by removing Cr(VI) from electroplating wastewater. PMID:20605325

  9. Why does tropical convective available potential energy (CAPE) increase with warming?

    NASA Astrophysics Data System (ADS)

    Seeley, Jacob T.; Romps, David M.

    2015-12-01

    Recent work has produced a theory for tropical convective available potential energy (CAPE) that highlights the Clausius-Clapeyron (CC) scaling of the atmosphere's saturation deficit as a driver of increases in CAPE with warming. Here we test this so-called "zero-buoyancy" theory for CAPE by modulating the saturation deficit of cloud-resolving simulations of radiative-convective equilibrium in two ways: changing the sea surface temperature (SST) and changing the environmental relative humidity (RH). For earthlike and warmer SSTs, undilute parcel buoyancy in the lower troposphere is insensitive to increasing SST because of a countervailing CC scaling that balances the increase in the saturation deficit; however, buoyancy increases dramatically with SST in the upper troposphere. Conversely, in the RH experiment, undilute buoyancy throughout the troposphere increases monotonically with decreasing RH. We show that the zero-buoyancy theory successfully predicts these contrasting behaviors, building confidence that it describes the fundamental physics of CAPE and its response to warming.

  10. Energy sector vulnerability to climate change: adaptation options to increase resilience

    NASA Astrophysics Data System (ADS)

    Newmark, R. L.; Bilello, D.; Macknick, J.; Hallett, K. C.; Anderson, R.; Tidwell, V. C.; Zamuda, C.

    2012-12-01

    Climate change will affect the energy sector in multiple ways. Potential impacts include those directly affecting energy infrastructure and operations, such as sea level rise combined with storm surge; increased frequency or intensity extreme events such as hurricanes, floods or droughts; alterations in the hydrologic cycle; as well as those indirectly affecting energy demand and system efficiencies such as increased average temperatures and heat waves, particularly during peak summer demand. Although these changes and challenges occur on different timescales; adaptation options must consider both long-term (chronic) changes as well as short-term (acute) affects as well as the benefits derived from adaptation actions relative to cost, degree of resiliency gained, and the probability of exposure to a given risk. Different energy sector stakeholders tend to focus on response strategies that address specific spatial and temporal scales based on their perceived risks. Here we assess climate change impacts to the Nation's electric sector reliability and consider potential responses necessary to ensure energy security and sustainability. For specific examples such as options to reduce freshwater needs for electricity generation or demand response strategies for extreme heat events, we examine both the technical and economic implications of adopting those strategies, including the national/regional costs for their implementation.

  11. Increased power to weight ratio of piezoelectric energy harvesters through integration of cellular honeycomb structures

    NASA Astrophysics Data System (ADS)

    Chandrasekharan, N.; Thompson, L. L.

    2016-04-01

    The limitations posed by batteries have compelled the need to investigate energy harvesting methods to power small electronic devices that require very low operational power. Vibration based energy harvesting methods with piezoelectric transduction in particular has been shown to possess potential towards energy harvesters replacing batteries. Current piezoelectric energy harvesters exhibit considerably lower power to weight ratio or specific power when compared to batteries the harvesters seek to replace. To attain the goal of battery-less self-sustainable device operation the power to weight ratio gap between piezoelectric energy harvesters and batteries need to be bridged. In this paper the potential of integrating lightweight honeycomb structures with existing piezoelectric device configurations (bimorph) towards achieving higher specific power is investigated. It is shown in this study that at low excitation frequency ranges, replacing the solid continuous substrate of conventional bimorph with honeycomb structures of the same material results in a significant increase in power to weight ratio of the piezoelectric harvester. At higher driving frequency ranges it is shown that unlike the traditional piezoelectric bimorph with solid continuous substrate, the honeycomb substrate bimorph can preserve optimum global design parameters through manipulation of honeycomb unit cell parameters. Increased operating lifetime and design flexibility of the honeycomb core piezoelectric bimorph is demonstrated as unit cell parameters of the honeycomb structures can be manipulated to alter mass and stiffness properties of the substrate, resulting in unit cell parameter significantly influencing power generation.

  12. Diagnosis and characterization of mania: Quantifying increased energy and activity in the human behavioral pattern monitor.

    PubMed

    Perry, William; McIlwain, Meghan; Kloezeman, Karen; Henry, Brook L; Minassian, Arpi

    2016-06-30

    Increased energy or activity is now an essential feature of the mania of Bipolar Disorder (BD) according to DSM-5. This study examined whether objective measures of increased energy can differentiate manic BD individuals and provide greater diagnostic accuracy compared to rating scales, extending the work of previous studies with smaller samples. We also tested the relationship between objective measures of energy and rating scales. 50 hospitalized manic BD patients were compared to healthy subjects (HCS, n=39) in the human Behavioral Pattern Monitor (hBPM) which quantifies motor activity and goal-directed behavior in an environment containing novel stimuli. Archival hBPM data from 17 schizophrenia patients were used in sensitivity and specificity analyses. Manic BD patients exhibited higher motor activity than HCS and higher novel object interactions. hBPM activity measures were not correlated with observer-rated symptoms, and hBPM activity was more sensitive in accurately classifying hospitalized BD subjects than observer ratings. Although the findings can only be generalized to inpatient populations, they suggest that increased energy, particularly specific and goal-directed exploration, is a distinguishing feature of BD mania and is best quantified by objective measures of motor activity. A better understanding is needed of the biological underpinnings of this cardinal feature. PMID:27138818

  13. Adsorption of selected volatile organic vapors on multiwall carbon nanotubes.

    PubMed

    Shih, Yang-hsin; Li, Mei-syue

    2008-06-15

    Carbon nanotubes are expected to play an important role in sensing, pollution treatment and separation techniques. This study examines the adsorption behaviors of volatile organic compounds (VOCs), n-hexane, benzene, trichloroethylene and acetone on two multiwall carbon nanotubes (MWCNTs), CNT1 and CNT2. Among these VOCs, acetone exhibits the highest adsorption capacity. The highest adsorption enthalpies and desorption energies of acetone were also observed. The strong chemical interactions between acetone and both MWCNTs may be the result from chemisorption on the topological defects. The adsorption heats of trichloroethylene, benzene, and n-hexane are indicative of physisorption on the surfaces of both MWCNTs. CNT2 presents a higher adsorption capacity than CNT1 due to the existence of an exterior amorphous carbon layer on CNT2. The amorphous carbon enhances the adsorption capacity of organic chemicals on carbon nanotubes. The morphological and structure order of carbon nanotubes are the primary affects on the adsorption process of organic chemicals. PMID:17980962

  14. Batch and fixed-bed adsorption of tartrazine azo-dye onto activated carbon prepared from apricot stones

    NASA Astrophysics Data System (ADS)

    Albroomi, H. I.; Elsayed, M. A.; Baraka, A.; Abdelmaged, M. A.

    2016-02-01

    This work describes the potential of utilizing prepared activated carbon from apricot stones as an efficient adsorbent material for tartrazine (TZ) azo-dye removal in a batch and dynamic adsorption system. The results revealed that activated carbons with well-developed surface area (774 m2/g) and pore volume (1.26 cm3/g) can be manufactured from apricot stones by H3PO4 activation. In batch experiments, effects of the parameters such as initial dye concentration and temperature on the removal of the dye were studied. Equilibrium was achieved in 120 min. Adsorption capacity was found to be dependent on the initial concentration of dye solution, and maximum adsorption was found to be 76 mg/g at 100 mg/L of TZ. The adsorption capacity at equilibrium (q e) increased from 22.6 to 76 mg/g with an increase in the initial dye concentrations from 25 to 100 mg/L. The thermodynamic parameters such as change in free energy (ΔG 0), enthalpy (ΔH 0) and entropy (ΔS 0) were determined and the positive value of (ΔH) 78.1 (K J mol-1) revealed that adsorption efficiency increased with an increase in the process temperature. In fixed-bed column experiments, the effect of selected operating parameters such as bed depth, flow rate and initial dye concentration on the adsorption capacity was evaluated. Increase in bed height of adsorption columns leads to an extension of breakthrough point as well as the exhaustion time of adsorbent. However, the maximum adsorption capacities decrease with increases of flow rate. The breakthrough data fitted well to bed depth service time and Thomas models with high coefficient of determination, R 2 ≥ 94.

  15. Short photoperiod increases energy intake, metabolic thermogenesis and organ mass in silky starlings Sturnus sericeus

    PubMed Central

    WANG, Jia-Qi; WANG, Jia-Jia; WU, Xu-Jian; ZHENG, Wei-Hong; LIU, Jin-Song

    2016-01-01

    Environmental cues play important roles in the regulation of an animal’s physiology and behavior. One such cue, photoperiod, plays an important role in the seasonal acclimatization of birds. It has been demonstrated that an animal’s body mass, basal metabolic rate (BMR), and energy intake, are all affected by photoperiod. The present study was designed to examine photoperiod induced changes in the body mass, metabolism and metabolic organs of the silky starling, Sturnus sericeus. Captive silky starlings increased their body mass and BMR during four weeks of acclimation to a short photoperiod. Birds acclimated to a short photoperiod also increased the mass of certain organs (liver, gizzard and small intestine), and both gross energy intake (GEI) and digestible energy intake (DEI), relative to those acclimated to a long photoperiod. Furthermore, BMR was positively correlated with body mass, liver mass, GEI and DEI. These results suggest that silky starlings increase metabolic thermogenesis when exposed to a short photoperiod by increasing their body and metabolic organ mass, and their GEI and DEI. These findings support the hypothesis that bird species from temperate climates typically display high phenotypic flexibility in thermogenic capacity. PMID:27029864

  16. Short photoperiod increases energy intake, metabolic thermogenesis and organ mass in silky starlings Sturnus sericeus.

    PubMed

    Wang, Jia-Qi; Wang, Jia-Jia; Wu, Xu-Jian; Zheng, Wei-Hong; Liu, Jin-Song

    2016-03-18

    Environmental cues play important roles in the regulation of an animal's physiology and behavior. One such cue, photoperiod, plays an important role in the seasonal acclimatization of birds. It has been demonstrated that an animal's body mass, basal metabolic rate (BMR), and energy intake, are all affected by photoperiod. The present study was designed to examine photoperiod induced changes in the body mass, metabolism and metabolic organs of the silky starling, Sturnus sericeus. Captive silky starlings increased their body mass and BMR during four weeks of acclimation to a short photoperiod. Birds acclimated to a short photoperiod also increased the mass of certain organs (liver, gizzard and small intestine), and both gross energy intake (GEI) and digestible energy intake (DEI), relative to those acclimated to a long photoperiod. Furthermore, BMR was positively correlated with body mass, liver mass, GEI and DEI. These results suggest that silky starlings increase metabolic thermogenesis when exposed to a short photoperiod by increasing their body and metabolic organ mass, and their GEI and DEI. These findings support the hypothesis that bird species from temperate climates typically display high phenotypic flexibility in thermogenic capacity. PMID:27029864

  17. Impact of the interaction with the positive charge in adsorption of benzene and other organic compounds from aqueous solutions on carbons

    NASA Astrophysics Data System (ADS)

    Terzyk, Artur P.; Ćwiertnia, Magdalena S.; Wiśniewski, Marek; Gauden, Piotr A.; Rychlicki, Gerhard; Szymański, Grzegorz S.

    2007-02-01

    We present the results of benzene adsorption at the acidic pH level determined on the series of chemically modified activated carbons and at three temperatures. The influence of carbon surface chemical composition on benzene adsorption is discussed. It is shown that the decrease in the pH level from 7 up to 1.5 increases benzene adsorption and the only exception is carbon modified with gaseous ammonia. Basing on the results of current work and those published previously (for phenol, paracetamol, acetanilide and aniline) and using the results of quantum chemistry calculations (DFT, Gaussian 98) we show, that the value of the energy of interaction with unit positive charge is crucial during the analysis of the influence of pH level on adsorption. Obtained results allow to predict the changes in adsorption of aromatics on carbons with the decrease in the pH level.

  18. Does severe dietary energy restriction increase binge eating in overweight or obese individuals? A systematic review.

    PubMed

    da Luz, F Q; Hay, P; Gibson, A A; Touyz, S W; Swinbourne, J M; Roekenes, J A; Sainsbury, A

    2015-08-01

    Severe dietary energy restriction is often used for overweight or obese individuals to achieve rapid weight loss and related health improvements. However, the extent of putative adverse effects on eating behaviour is unknown. We thus systematically searched seven databases for studies that assessed binge eating before and after severe dietary energy restriction (low or very low energy diets) in overweight or obese individuals. Fifteen clinically supervised interventions from 10 publications (nine of which involved only women) were included. Among individuals with clinically relevant pre-treatment binge eating disorder, severe dietary energy restriction significantly decreased binge eating in all four interventions involving this population, at least during the weight loss programme. In contrast, no consistent association between severe dietary energy restriction and the onset of bingeing was found in 11 interventions involving individuals without pre-treatment binge eating disorder, with four such interventions showing significant increases, two showing no change, and five showing significant decreases in binge eating. We conclude that clinically supervised severe dietary energy restriction appears safe and beneficial for overweight or obese individuals with pre-treatment binge eating disorder, and does not necessarily trigger binge eating in those without binge eating disorder. PMID:26094791

  19. ARSENIC TREATMENT BY ADSORPTIVE TECHNOLOGY

    EPA Science Inventory

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

  20. Evaluation of the isosteric heat of adsorption at zero coverage for hydrogen on activated carbons

    NASA Astrophysics Data System (ADS)

    Dohnke, E.; Beckner, M.; Romanos, J.; Olsen, R.; Wexler, C.; Pfeifer, P.

    2011-03-01

    Activated carbons made from corn cob show promise as materials for high-capacity hydrogen storage. As part of our characterization of these materials, we are interested in learning how different production methods affect the adsorption energies. In this talk, we will show how hydrogen adsorption isotherms may be used to calculate these adsorption energies at zero coverage using Henry's law. We will additionally discuss differences between the binding energy and the isosteric heat of adsorption by applying this analysis at different temperatures.

  1. 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…

  2. Adsorption of divalent metals to metal oxide nanoparicles: Competitive and temperature effects

    NASA Astrophysics Data System (ADS)

    Grover, Valerie Ann

    The presence of metals in natural waters is becoming a critical environmental and public health concern. Emerging nanotechnology and the use of metal oxide nanoparticles has been identified as a potential remediation technique in removing metals from water. However, practical applications are still being explored to determine how to apply their unique chemical and physical properties for full scale remediation projects. This thesis investigates the sorption properties of Cd(II), Cu(II), Pb(II) and Zn(II) to hematite (alpha-Fe2O3) and titanium dioxide (TiO2) nanoparticles in single- and binary-adsorbate systems. Competitive sorption was evaluated in 1L batch binary-metal systems with 0.05g/L nano-hematite at pH 8.0 and pH 6.0. Results indicate that the presence of a secondary metal can affect the sorption process depending upon the molar ratios, such as increased or reduced adsorption. Thermodynamic properties were also studied in order to better understand the effects of temperature on equilibrium and kinetic adsorption capabilities. Understanding the thermodynamic properties can also give insight to determine if the sorption process is a physical, chemical or ion exchange reaction. Thermodynamic parameters such as enthalpy (DeltaH), entropy (DeltaS), and Gibbs free energy (DeltaG) were evaluated as a function of temperature, pH, and metal concentration. Results indicate that Pb(II) and Cu(II) adsorption to nano-hematite was an endothermic and physical adsorption process, while Zn(II) and Cd(II) adsorption was dependent upon the adsorbed concentration evaluated. However, metal adsorptions to nano-titanium dioxide were all found to be endothermic and physical adsorption processes; the spontaneity of metal adsorption was temperature dependent for both metal oxide nanoparticles.

  3. Adsorption of CO molecule on AlN nanotubes by parallel electric field.

    PubMed

    Peyghan, Ali Ahmadi; Baei, Mohammad T; Hashemian, Saeedeh; Torabi, Parviz

    2013-02-01

    The behavior of the carbon monoxide (CO) adsorbed on the external surface of H-capped (6,0) zigzag single-walled aluminum nitride nanotube (AlNNT) was studied using parallel and transverse electric field (strengths 0-140 × 10(-4) a.u.) and density functional calculations. The calculated adsorption energies of the CO/AlNNT complex increased with increasing parallel electric field intensity, whereas the adsorption energy values at the applied transverse electric field show a significant reverse trend. The calculated adsorption energies of the complex at the applied parallel electric field strengths increased gradually from -0.42 eV at zero field strength to -0.80 eV at a field strength of 140 × 10(-4) a.u. The considerable changes in the adsorption energies and energy gap values generated by the applied parallel electric field strengths show the high sensitivity of the electronic properties of AlNNT towards the adsorption of CO on its surface. Analysis of structural parameters indicates that the nanotube is resistant to external electric field strengths. The dipole moment variations in the complex show a significant change in the presence of parallel and transverse electric fields, which results in much stronger interactions at higher electric field strengths. Additionally, the natural bond orbital charges, quantum molecular descriptors, and molecular orbital energies of the complex show that the nanotube can absorb CO molecule in its pristine form at a high applied parallel electric field, and that the nanotube can be used as a CO storage medium. PMID:23073700

  4. Dissociative adsorption of water on Au/MgO/Ag(001) from first principles calculations

    NASA Astrophysics Data System (ADS)

    Nevalaita, J.; Häkkinen, H.; Honkala, K.

    2015-10-01

    The molecular and dissociative adsorption of water on a Ag-supported 1 ML, 2 ML and 3 ML-a six atomic layer-thick MgO films with a single Au adatom is investigated using density functional theory calculations. The obtained results are compared to a bulk MgO(001) surface with an Au atom. On thin films the negatively charged Au strengthens the binding of the polar water molecule due to the attractive Au-H interaction. The adsorption energy trends of OH and H with respect to the film thickness depend on an adsorption site. In the case OH or H binds atop Au on MgO/Ag(001), the adsorption becomes more exothermic with the increasing film thickness, while the reverse trend is seen when the adsorption takes place on bare MgO/Ag(001). This behavior can be explained by different bonding mechanisms identified with the Bader analysis. Interestingly, we find that the rumpling of the MgO film and the MgO-Ag interface distance correlate with the charge transfer over the thin film and the interface charge, respectively. Moreover, we employ a modified Born-Haber-cycle to analyze the effect of film thickness to the adsorption energy of isolated Au and OH species on MgO/Ag(001). The analysis shows that the attractive Coulomb interaction between the negatively charged adsorbate and the positive MgO-Ag-interface does not completely account for the weaker binding with increasing film thickness. The redox energy associated with the charge transfer from the interface to the adsorbate is more exothermic with the increasing film thickness and partly compensates the decrease in the attractive Coulomb interaction.

  5. Energy expended playing video console games: an opportunity to increase children's physical activity?

    PubMed

    Maddison, Ralph; Mhurchu, Cliona Ni; Jull, Andrew; Jiang, Yannan; Prapavessis, Harry; Rodgers, Anthony

    2007-08-01

    This study sought to quantify the energy expenditure and physical activity associated with playing the "new generation" active and nonactive console-based video games in 21 children ages 10-14 years. Energy expenditure (kcal) derived from oxygen consumption (VO2) was continuously assessed while children played nonactive and active console video games. Physical activity was assessed continuously using the Actigraph accelerometer. Significant (p < .001) increases from baseline were found for energy expenditure (129-400%), heart rate (43-84%), and activity counts (122-1288 versus 0-23) when playing the active console video games. Playing active console video games over short periods of time is similar in intensity to light to moderate traditional physical activities such as walking, skipping, and jogging. PMID:18019591

  6. A cascadable circular concentrator with parallel compressed structure for increasing the energy density

    NASA Astrophysics Data System (ADS)

    Ku, Nai-Lun; Chen, Yi-Yung; Hsieh, Wei-Che; Whang, Allen Jong-Woei

    2012-02-01

    Due to the energy crisis, the principle of green energy gains popularity. This leads the increasing interest in renewable energy such as solar energy. Thus, how to collect the sunlight for indoor illumination becomes our ultimate target. With the environmental awareness increasing, we use the nature light as the light source. Then we start to devote the development of solar collecting system. The Natural Light Guiding System includes three parts, collecting, transmitting and lighting part. The idea of our solar collecting system design is a concept for combining the buildings with a combination of collecting modules. Therefore, we can use it anyplace where the sunlight can directly impinges on buildings with collecting elements. In the meantime, while collecting the sunlight with high efficiency, we can transmit the sunlight into indoor through shorter distance zone by light pipe where we needs the light. We proposed a novel design including disk-type collective lens module. With the design, we can let the incident light and exit light be parallel and compressed. By the parallel and compressed design, we make every output light become compressed in the proposed optical structure. In this way, we can increase the ratio about light compression, get the better efficiency and let the energy distribution more uniform for indoor illumination. By the definition of "KPI" as an performance index about light density as following: lm/(mm)2, the simulation results show that the proposed Concentrator is 40,000,000 KPI much better than the 800,000 KPI measured from the traditional ones.

  7. Differential Power Processing for Increased Energy Production and Reliability of Photovoltaic Systems

    SciTech Connect

    Shenoy, PS; Kim, KA; Johnson, BB; Krein, PT

    2013-06-01

    Conventional energy conversion architectures in photovoltaic (PV) systems are often forced to tradeoff conversion efficiency and power production. This paper introduces an energy conversion approach that enables each PV element to operate at its maximum power point (MPP) while processing only a small fraction of the total power produced. This is accomplished by providing only the mismatch in the MPP current of a set of series-connected PV elements. Differential power processing increases overall conversion efficiency and overcomes the challenges associated with unmatched MPPs (due to partial shading, damage, manufacturing tolerances, etc.). Several differential power processing architectures are analyzed and compared with Monte Carlo simulations. Local control of the differential converters enables distributed protection and monitoring. Reliability analysis shows significantly increased overall system reliability. Simulation and experimental results are included to demonstrate the benefits of this approach at both the panel and subpanel level.

  8. Adsorption of gases from SF6 decomposition on aluminum-doped SWCNTs: a density functional theory study

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoxing; Gui, Yingang; Dai, Ziqiang

    2015-07-01

    Adsorption of gases produced by SF6 decomposition (i.e., SO2, H2S, SOF2, SO2F2, and CF4) by aluminum-doped zigzag (8, 0) single-walled carbon nanotubes (Al-SWCNTs) was investigated based on first-principles density functional theory (DFT). Different binding sites were considered to determine the most stable structures. Furthermore, adsorption energy, density of state, band structure, frontier molecular orbital, and population were analyzed to interpret the mechanism of gas adsorption on the surface of Al-SWCNTs. The calculation results predicted that the Al atom acted as an active site to adsorb the SF6 decomposition products in the adsorption process. SO2, H2S, and CF4 molecules were adsorbed on the sidewall of Al-SWCNTs by physisorption, whereas SOF2 and SO2F2 were molecularly chemisorbed. Conductivity of Al-SWCNTs was increased when the gas molecules of SO2, H2S, and SO2F2 were adsorbed. Conversely, SOF2 adsorption slightly decreased the conductivity of the adsorption system. Al-SWCNTs were insensitive to CF4. The different responses in conductivity of Al-SWCNTs for different gas molecule adsorptions present a potential selective and sensitive gas detection sensor.

  9. Nanoporous chalcogenides for adsorption and gas separation.

    PubMed

    Ori, Guido; Massobrio, Carlo; Pradel, Annie; Ribes, Michel; Coasne, Benoit

    2016-05-21

    The adsorption and gas separation properties of amorphous porous chalcogenides such as GeS2 are investigated using statistical mechanics molecular simulation. Using a realistic molecular model of such amorphous adsorbents, we show that they can be used efficiently to separate different gases relevant to environmental and energy applications (H2, CO2, CH4, N2). In addition to shedding light on the microscopic adsorption mechanisms, we show that coadsorption in this novel class of porous materials can be described using the ideal adsorbed solution theory (IAST). Such a simple thermodynamic model, which allows avoiding complex coadsorption measurements, describes the adsorption of mixture from pure component adsorption isotherms. Our results, which are found to be in good agreement with available experimental data, paves the way for the design of gas separation membranes using the large family of porous chalcogenides. PMID:27126718

  10. RYGB progressively increases avidity for a low-energy, artificially sweetened diet in female rats.

    PubMed

    Geary, Nori; Bächler, Thomas; Whiting, Lynda; Lutz, Thomas A; Asarian, Lori

    2016-03-01

    Weight re-gain within 2 y after Roux-en-Y gastric bypass (RYGB) is significantly associated with increased intake of and cravings for sweet foods. Here we describe a novel model of this late increase in sweet appetite. Ovariectomized RYGB and Sham-operated rats, with or without estradiol treatment, were maintained on Ensure liquid diet and offered a low-energy, artificially sweetened diet (ASD) 2 h/d. First, we tested rats more than six months after RYGB. ASD meals were larger in RYGB than Sham rats, whereas Ensure meals were smaller. General physical activity increased during ASD meals in RYGB rats, but not during Ensure meals. Second, new rats were adapted to ASD before surgery, and were then offered ASD again during 4-10 wk following surgery. Estradiol-treated RYGB rats lost the most weight and progressively increased ASD intake to >20 g/2 h in wk 9-10 vs. ∼3 g/2 h in Sham rats. Finally, the same rats were then treated with leptin or saline for 8 d. Leptin did not affect body weight, Ensure intake, or activity during meals, but slightly reduced ASD intake in estradiol-treated RYGB rats. Food-anticipatory activity was increased in estradiol-treated RYGB rats during the saline-injection tests. Because increased meal-related physical activity together with larger meals is evidence of hunger in rats, these data suggest that (1) RYGB can increase hunger for a low-energy sweet food in rats and (2) low leptin levels contribute to this hunger, but are not its only cause. This provides a unique rat model for the increased avidity for sweets that is significantly associated with weight recidivism late after RYGB. PMID:26707654

  11. Does EU's energy dependence on Russia increase price volatility for consumers?

    NASA Astrophysics Data System (ADS)

    Yekeler, Zeynep

    Europe's dependence on natural gas imports from Russia has raised questions about energy risk and the vulnerability of the European countries, especially after the supply cuts in 2006, 2008, 2009, and 2012. The implementation of the Third Energy Package to finally unify European energy markets by linking the states located on the periphery to the well connected gas hubs in Northern Europe has been slow due to a lack of political will across Europe. This has enabled Russian Gazprom to retain its position as a major player in European markets and hinder any European effort to diversify the energy portfolio of the region. Using residential natural gas and electricity price data from 2000 through 2014, this paper analyzes the impact of EU's import reliance on natural gas from Russia and the supply disruptions on the volatility of natural gas and electricity prices through a fixed effects regression model. Results indicate that while the size of Russian natural gas imports does not significantly affect natural gas and electricity price volatility in EU countries, security supply measures such as natural gas stocks matter, especially for Southeast European countries that consistently pay more according to the results. The paper concludes by discussing the importance of formulating policies that not only aim to reduce overall EU dependence but minimize Southeastern Europe's vulnerabilities. Policy suggestions include increasing cross-border interconnectors and storage capacity as well as increasing LNG import capacity by building regasification terminals in periphery countries like Greece, Bulgaria, Romania and Slovenia.

  12. Increases Proposed for U.S. Energy Department, But EPA Funding Would Be Cut

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2008-03-01

    The Bush administration's proposed fiscal year (FY) 2009 budget request would cut the U.S. Environmental Protection Agency's (EPA) funding to US$7.14 billion, a decrease of $330 million, or 4.4%, from the 2008 funding level. However, the administration's proposed budget request for the U.S. Department of Energy (DOE) would boost that agency's funding to $25 billion, an increase of $1.07 billion over 2008.

  13. Injection of a Phase Modulated Source into the Z-Beamlet Laser for Increased Energy Extraction.

    SciTech Connect

    Rambo, Patrick K.; Armstrong, Darrell J.; Schwarz, Jens; Smith, Ian C; Shores, Jonathon; Speas, Christopher; Porter, John L.

    2014-11-01

    The Z-Beamlet laser has been operating at Sandia National Laboratories since 2001 to provide a source of laser-generated x-rays for radiography of events on the Z-Accelerator. Changes in desired operational scope have necessitated the increase in pulse duration and energy available from the laser system. This is enabled via the addition of a phase modulated seed laser as an alternative front-end. The practical aspects of deployment are discussed here.

  14. Increased energy expenditure by a seabird in response to higher food abundance

    USGS Publications Warehouse

    Jodice, P.G.R.; Roby, D.D.; Suryan, R.M.; Irons, D.B.; Turco, K.R.; Brown, E.D.; Thedinga, J.F.; Visser, G.H.

    2006-01-01

    Variability in forage fish abundance strongly affects seabird behavior and reproductive success, although details of this relationship are unclear. During 1997 and 1998, we measured (1) daily energy expenditure (DEE) of 80 parent black-legged kittiwakes Rissa tridactyla at 2 colonies in Prince William Sound, Alaska (North Icy Bay and Shoup Bay), (2) abundance of surface-schooling forage fishes within the foraging range of each colony, and (3) diet composition, energy delivery rates to nestlings, and reproductive success of kittiwakes at these same colonies. Female DEE was highest at North Icy Bay in 1998, while male DEE did not differ by colony year. Abundances of Pacific herring Clupea pallasi and sand lance Ammodytes hexapterus were highest near North Icy Bay in 1998 and nearly egual in density, although Age 1+ herring comprised the majority of the diet there. Energy delivery rates to nestlings, nestling growth rates, and productivity were also highest at North Icy Bay in 1998. We suggest that female kittiwakes responded to the increased abundance of Age 1+ herring near North Icy Bay in 1998 by increasing their DEE, which in turn positively affected reproductive success. Given that adult kittiwakes have been shown to suffer decreased survival as a response to increased energy expenditure during brood rearing, the positive correlation we observed between increased abundance of a high quality food source, parental effort, and productivity is consistent with maximizing lifetime reproductive success. The lack of a response in male DEE suggests that brood-rearing roles in kittiwakes differ between genders. ?? Inter-Research 2006.

  15. Carbon adsorption on tungsten and electronic field emission

    NASA Astrophysics Data System (ADS)

    Márquez-Mijares, Maykel; Lepetit, Bruno; Lemoine, Didier

    2016-03-01

    Electronic emission taking place at the electrodes of high voltage systems and responsible for detrimental breakdown processes is known to be strongly dependent on the cathode surface state and in particular on the presence of carbon contamination. To understand better the effect of carbon adsorption on cathode electronic emission, density functional theory calculations are reported for bulk bcc tungsten as well as for clean and carbon-covered W(100) surfaces for several coverages up to 2 ML. Adsorption geometries and energies, work functions and electronic densities of states are analyzed to assess the effect of the presence of adlayers on surface electronic field emission properties. It is shown that flat carbon adlayer deposition on clean W(100) surfaces induces an increase of the surface work function and a decrease of electronic density near the Fermi level. Both factors contribute to reducing electronic field emission levels.

  16. Adsorption kinetics of phosphate and arsenate on goethite. A comparative study.

    PubMed

    Luengo, Carina; Brigante, Maximiliano; Avena, Marcelo

    2007-07-15

    The adsorption kinetics of phosphate and arsenate on goethite is studied and compared. Batch adsorption experiments were performed at different adsorbate concentrations, pH, temperatures and stirring rates. For both oxoanions the adsorption rate increases by increasing adsorbate concentration, decreasing pH and increasing temperature. It does not change by changing stirring rate. The adsorption takes place in two processes: a fast one that takes place in less than 5 min and a slow one that takes place in several hours or more. The rate of the slow process does not depend directly on the concentration of phosphate or arsenate in solution, but depends linearly on the amount of phosphate or arsenate that was adsorbed during the fast process. Apparent activation energies and absence of stirring rate effects suggest that the slow process is controlled by diffusion into pores, although the evidence is not conclusive. The similarities in the adsorption kinetics of phosphate and arsenate are quantitatively shown by using a three-parameters equation that takes into account both the fast and the slow processes. These similarities are in line with the similar reactivity that phosphate and arsenate have in general and may be important for theoretical and experimental studies of the fate of these oxoanions in the environment. PMID:17448491

  17. Geothermal energy for the increased recovery of copper by flotation enhancement

    SciTech Connect

    White, D.H.; Goldstone, L.A.

    1982-08-01

    The possible use of geothermal energy (a) to speed the recovery of copper from ore flotation and/or leaching of flotation tailings and (b) to utilize geothermal brines to replace valuable fresh water in copper flotation operations was evaluated. Geothermal energy could be used to enhance copper and molybdenum recovery in mineral flotation by increasing the kinetics of the flotation process. In another approach, geothermal energy could be used to heat the leaching solution which might permit greater copper recovery using the same residence time in a tailings leach facility. Since there is no restriction on the temperature of the leaching fluid, revenues generated from the additional copper recovered would be greater for tailings leach operations than for other types of leach operations (for example, dump leaching operation) for which temperature restrictions exist. The estimated increase in total revenues resulting from two percent increase copper recovery in a 50,000 tons ore/day plant was estimated to be over $2,000,000 annually. It would require an estimated geothermal investment of about $2,130,000 for a geothermal well and pumping system. Thus, the capital investment would be paid out in about one year. Furthermore, considerable savings of fresh waters and process equipment are possible if the geothermal waters can be used directly in the mine-mill operations, which is believed to be practical.

  18. The Application of High Energy Ignition and Boosting/Mixing Technology to Increase Fuel Economy in Spark Ignition Gasoline Engines by Increasing EGR Dilution Capability

    SciTech Connect

    Keating, Edward; Gough, Charles

    2015-07-07

    This report summarizes activities conducted in support of the project “The Application of High Energy Ignition and Boosting/Mixing Technology to Increase Fuel Economy in Spark Ignition Gasoline Engines by Increasing EGR Dilution Capability” under COOPERATIVE AGREEMENT NUMBER DE-EE0005654, as outlined in the STATEMENT OF PROJECT OBJECTIVES (SOPO) dated May 2012.

  19. Crashworthiness of Aluminium Tubes; Part 2: Improvement of Hydroforming Operation to Increase Absorption Energy

    SciTech Connect

    D'Amours, Guillaume; Rahem, Ahmed; Mayer, Robert; Williams, Bruce; Worswick, Michael

    2007-05-17

    The motivation to reduce overall vehicle weight within the automotive sector drives the substitution of lightweight materials such as aluminium alloys for structural components. Such a substitution requires a significant amount of development to manufacture structurally parts such that the energy absorption characteristics are not sacrificed in the event of crash. The effects of the manufacturing processes on the crash performance of automotive structural components must be better understood to ensure improved crashworthiness. This paper presents results of an experimental and numerical investigation of the crash response and energy absorption properties of impacted hydroformed aluminium alloy tubes. Crash experiments on hydroformed tubes were performed using a deceleration sled test at the General Motors Technical Center. Results from axial crush testing showed that an important parameter that influences the energy absorption characteristics during crash was the thickness reduction caused by circumferential expansion of the tube during hydroforming. It was found that that the energy absorption decreased as the corner radius decreased, which results because of increased thinning. Sensitivity studies of end feeding parameters, such as end feed level and profile, were carried out to evaluate their impact on the energy absorption of the aluminium tubes.

  20. Crashworthiness of Aluminium Tubes; Part 2: Improvement of Hydroforming Operation to Increase Absorption Energy

    NASA Astrophysics Data System (ADS)

    D'Amours, Guillaume; Rahem, Ahmed; Mayer, Robert; Williams, Bruce; Worswick, Michael

    2007-05-01

    The motivation to reduce overall vehicle weight within the automotive sector drives the substitution of lightweight materials such as aluminium alloys for structural components. Such a substitution requires a significant amount of development to manufacture structurally parts such that the energy absorption characteristics are not sacrificed in the event of crash. The effects of the manufacturing processes on the crash performance of automotive structural components must be better understood to ensure improved crashworthiness. This paper presents results of an experimental and numerical investigation of the crash response and energy absorption properties of impacted hydroformed aluminium alloy tubes. Crash experiments on hydroformed tubes were performed using a deceleration sled test at the General Motors Technical Center. Results from axial crush testing showed that an important parameter that influences the energy absorption characteristics during crash was the thickness reduction caused by circumferential expansion of the tube during hydroforming. It was found that that the energy absorption decreased as the corner radius decreased, which results because of increased thinning. Sensitivity studies of end feeding parameters, such as end feed level and profile, were carried out to evaluate their impact on the energy absorption of the aluminium tubes.

  1. Dystropathology increases energy expenditure and protein turnover in the mdx mouse model of duchenne muscular dystrophy.

    PubMed

    Radley-Crabb, Hannah G; Marini, Juan C; Sosa, Horacio A; Castillo, Liliana I; Grounds, Miranda D; Fiorotto, Marta L

    2014-01-01

    The skeletal muscles in Duchenne muscular dystrophy and the mdx mouse model lack functional dystrophin and undergo repeated bouts of necrosis, regeneration, and growth. These processes have a high metabolic cost. However, the consequences for whole body energy and protein metabolism, and on the dietary requirements for these macronutrients at different stages of the disease, are not well-understood. This study used juvenile (4- to 5- wk-old) and adult (12- to 14-wk-old) male dystrophic C57BL/10ScSn-mdx/J and age-matched C57BL/10ScSn/J control male mice to measure total and resting energy expenditure, food intake, spontaneous activity, body composition, whole body protein turnover, and muscle protein synthesis rates. In juvenile mdx mice that have extensive muscle damage, energy expenditure, muscle protein synthesis, and whole body protein turnover rates were higher than in age-matched controls. Adaptations in food intake and decreased activity were insufficient to meet the increased energy and protein needs of juvenile mdx mice and resulted in stunted growth. In (non-growing) adult mdx mice with less severe dystropathology, energy expenditure, muscle protein synthesis, and whole body protein turnover rates were also higher than in age-matched controls. Food intake was sufficient to meet their protein and energy needs, but insufficient to result in fat deposition. These data show that dystropathology impacts the protein and energy needs of mdx mice and that tailored dietary interventions are necessary to redress this imbalance. If not met, the resultant imbalance blunts growth, and may limit the benefits of therapies designed to protect and repair dystrophic muscles. PMID:24586653

  2. Molecular dynamics study of calcite, hydrate and the temperature effect on CO2 transport and adsorption stability in geological formations

    NASA Astrophysics Data System (ADS)

    Van Cuong, Phan; Kvamme, Bjørn; Kuznetsova, Tatiana; Jensen, Bjørnar

    2012-06-01

    Molecular dynamics (MD) simulations at several different temperatures were run to investigate the transport, adsorption, and stability of carbon dioxide (CO2) and water phases in contact with a ? calcite surface. All simulated systems showed evidence of CO2 transport and interface stability heavily affected by the presence of calcite and the simulation temperature. The number of CO2 molecules that successfully traversed the water layer and adsorbed on the calcite surface increased with temperature, while the adsorption stability (indicated by the adsorption energy) decreased. It was found that the short-range potential has a significant impact on the preferred CO2 orientation and adsorption selectivity. Carbon dioxide tended to fill partial hydrate cavities at the water-hydrate interface, potentially promoting the formation of new hydrate. These findings indicate the need to consider the implications that CO2 injection will have for reservoirs with pre-existing clathrate hydrates.

  3. Calcium lignosulfonate adsorption and desorption on Berea sandstone.

    PubMed

    Grigg, Reid B; Bai, Baojun

    2004-11-01

    This paper describes adsorption and desorption studies carried out with calcium lignosulfonate (CLS) on Berea sandstone. Circulation experiments were performed to determine CLS adsorption isotherms and the effects of CLS concentration, temperature, salinity, brine hardness, and injection rate on adsorption density. Flow-through experiments were performed to assess the reversibility of CLS adsorption and the influence of postflush rate, brine concentration, brine hardness, brine pH, and temperature on the desorption process. Results indicate that CLS adsorption isotherms on Berea sandstone follow the Freundlich isotherm law. The results presented in this paper on the effects of CLS adsorption and desorption on Berea sandstone show that: (1) increasing CLS concentration and salinity increases CLS adsorption density; (2) increasing temperature will decrease adsorption density; (3) increasing injection rate of CLS solution will slightly decrease CLS adsorption density; (4) postflush rate and salinity of brine have a large impact on the CLS desorption process; (5) the adsorption and desorption process are not completely reversible; and (5) temperature and pH of the postflush brine have little effect on desorption. PMID:15380409

  4. HYDROGEN ADSORPTION ON β-TiAl (001) AND Ni/TiAl (001) SURFACES

    NASA Astrophysics Data System (ADS)

    Mubarak, A. A. Karim; Alelaimi, Mahmoud

    2014-04-01

    In this paper, we present first principles calculations of the energetic, electronic and magnetic properties of the variant termination of TiAl (001) and Ni/TiAl (001) surfaces with and without hydrogen atoms. The calculations have been performed within the density functional theory using full-potential linearized augmented plane wave method. The generalized gradient approximation (GGA) is utilized as the exchange-correlation energy. The octahedral site is the stable absorption site of H atom in the β-TiAl system. This absorption reduces the cohesive energy of β-TiAl system due to increase in the lattice constant. The surface energy for both TiAl (001) terminations is calculated. The stable adsorption site of H atoms on the variant termination of TiAl (001) surface is performed. The adsorption energy of hydrogen on Ti is more energetic than that on Al. The adsorption of H atom on both terminations of H/Ni/TiAl (001) is more preferable at the bridge site. The adsorption energies are enhanced on Ni atom due to the contraction between d-Ni bands and TiAl substrate band.

  5. Kaempferia parviflora extract increases energy consumption through activation of BAT in mice

    PubMed Central

    Yoshino, Susumu; Kim, Minji; Awa, Riyo; Kuwahara, Hiroshige; Kano, Yuriko; Kawada, Teruo

    2014-01-01

    Kaempferia parviflora (KP) is a member of the ginger family and is known in Thailand as Thai ginseng, Krachai Dam or Black Ginger. TheK. parviflora extract (KPE) was previously reported to have a number of physiological effects; however, the antiobesity effects of KPE and its mechanisms remain to be elucidated. In this study, we conducted KPE feeding experiments (low dose: 0.5% KPE, high dose: 1.0% KPE) in mice to examine the antiobesity effects. For both 0.5% KPE and 1.0% KPE, 7 weeks’ feeding of KPE contained in a high-fat diet (HFD) significantly decreased body weight gain, intraabdominal fat accumulation, and plasma triglyceride and leptin levels. Concurrently, KPE administration increased oxygen consumption in mice fed on a HFD. We also found that 1.0% KPE feeding significantly increased the uncoupling protein 1 (UCP1) expression in brown adipose tissue (BAT). Moreover, KPE administration increased urinary noradrenaline secretion levels. These results demonstrate that KPE promotes energy metabolism by activation of BAT, at both doses and up-regulation of UCP1 protein at a high dose. Although numerous challenges remain, the present study demonstrated that KPE suppresses HFD-induced obesity through increased energy metabolism. PMID:25493179

  6. Kaempferia parviflora extract increases energy consumption through activation of BAT in mice.

    PubMed

    Yoshino, Susumu; Kim, Minji; Awa, Riyo; Kuwahara, Hiroshige; Kano, Yuriko; Kawada, Teruo

    2014-11-01

    Kaempferia parviflora (KP) is a member of the ginger family and is known in Thailand as Thai ginseng, Krachai Dam or Black Ginger. TheK. parviflora extract (KPE) was previously reported to have a number of physiological effects; however, the antiobesity effects of KPE and its mechanisms remain to be elucidated. In this study, we conducted KPE feeding experiments (low dose: 0.5% KPE, high dose: 1.0% KPE) in mice to examine the antiobesity effects. For both 0.5% KPE and 1.0% KPE, 7 weeks' feeding of KPE contained in a high-fat diet (HFD) significantly decreased body weight gain, intraabdominal fat accumulation, and plasma triglyceride and leptin levels. Concurrently, KPE administration increased oxygen consumption in mice fed on a HFD. We also found that 1.0% KPE feeding significantly increased the uncoupling protein 1 (UCP1) expression in brown adipose tissue (BAT). Moreover, KPE administration increased urinary noradrenaline secretion levels. These results demonstrate that KPE promotes energy metabolism by activation of BAT, at both doses and up-regulation of UCP1 protein at a high dose. Although numerous challenges remain, the present study demonstrated that KPE suppresses HFD-induced obesity through increased energy metabolism. PMID:25493179

  7. SirT1 gain-of-function increases energy efficiency and prevents diabetes in mice

    PubMed Central

    Banks, Alexander S.; Kon, Ning; Knight, Colette; Matsumoto, Michihiro; Gutiérrez-Juárez, Roger; Rossetti, Luciano; Gu, Wei; Accili, Domenico

    2011-01-01

    Summary In yeast, worms and flies, an extra copy of the gene encoding the Sirtuin Sir2 increases metabolic efficiency, as does administration of polyphenols like resveratrol, thought to act through Sirtuins. But evidence that Sirtuin gain-of-function results in increased metabolic efficiency in mammals is limited. We generated transgenic mice with moderate overexpression of SirT1, designed to mimic the Sirtuin gain-of-function that improves metabolism in C.elegans. These mice exhibit normal insulin sensitivity, but decreased food intake and locomotor activity, resulting in decreased energy expenditure. However, in various models of insulin resistance and diabetes, SirT1 transgenics display improved glucose tolerance due to decreased hepatic glucose production and increased adiponectin levels, without changes in body weight or composition. We conclude that SirT1 gain-of-function primes the organism for metabolic adaptation to insulin resistance, increasing hepatic insulin sensitivity and decreasing whole-body energy requirements. These findings have important implications for Sirtuin-based therapies in humans. PMID:18840364

  8. Strategies to increase vegetable or reduce energy and fat intake induce weight loss in adults.

    PubMed

    Tanumihardjo, Sherry A; Valentine, Ashley R; Zhang, Zhumin; Whigham, Leah D; Lai, HuiChuan J; Atkinson, Richard L

    2009-05-01

    For obese individuals seeking to optimize health and well-being, healthy dietary strategies are important. Vegetables and fruits contribute to a healthy diet, and increased consumption may cause weight reduction by displacing foods high in energy and fat. The objective of this study was to determine if advising high vegetable (8 servings) and moderate fruit (2-3 servings) consumption would result in weight reduction in obese individuals. We compared this to advising a more traditional strategy of reducing daily energy intake by 500 kcal (2.1 MJ)/d and limiting energy from fat to energy reduction diet), and the energy and fat reduction diet resulted in lower weight over time (P<0.0001, treatment effect). Total cholesterol and cholesterol:HDL decreased after 3 mo in both groups (Pincreasing vegetable intake can assist individuals to maintain weight. PMID:19234056

  9. Feasibility of using a compact elliptical device to increase energy expenditure during sedentary activities

    PubMed Central

    Rovniak, Liza S.; Denlinger, LeAnn; Duveneck, Ellen; Sciamanna, Christopher N.; Kong, Lan; Freivalds, Andris; Ray, Chester A.

    2013-01-01

    Objectives This study aimed to evaluate the feasibility of using a compact elliptical device to increase energy expenditure during sedentary activities. A secondary aim was to evaluate if two accelerometers attached to the elliptical device could provide reliable and valid assessments of participants’ frequency and duration of elliptical device use. Design Physically inactive adults (n = 32, age range = 25–65) were recruited through local advertisements and selected using stratified random sampling based on sex, body mass index (BMI), and age. Methods Indirect calorimetry was used to assess participants’ energy expenditure while seated and while using the elliptical device at a self-selected intensity level. Participants also self-reported their interest in using the elliptical device during sedentary activities. Two Actigraph GT3X accelerometers were attached to the elliptical device to record time-use patterns. Results Participants expended a median of 179.1 kilocalories per hour while using the elliptical device (range = 108.2–269.0), or a median of 87.9 more kilocalories (range = 19.7–178.6) than they would expend per hour of sedentary sitting. Participants reported high interest in using the elliptical device during TV watching and computer work, but relatively low interest in using the device during office meetings. Women reported greater interest in using the elliptical device than men. The two accelerometers recorded identical time-use patterns on the elliptical device and demonstrated concurrent validity with time-stamped computer records. Conclusions Compact elliptical devices could increase energy expenditure during sedentary activities, and may provide proximal environmental cues for increasing energy expenditure across multiple life domains. PMID:24035273

  10. To what extent can mutual shifting of folded carbonaceous walls in slit-like pores affect their adsorption properties?

    PubMed

    Furmaniak, Sylwester; Terzyk, Artur P; Gauden, Piotr A; Włoch, Jerzy; Kowalczyk, Piotr; Werengowska-Ciećwierz, Karolina; Wiśniewski, Marek; Harris, Peter J F

    2016-01-13

    We have performed systematic Monte Carlo studies on the influence of shifting the walls in slit-like systems constructed from folded graphene sheets on their adsorption properties. Specifically, we have analysed the effect on the mechanism of argon adsorption (T  =  87 K) and on adsorption and separation of three binary gas mixtures: CO2/N2, CO2/CH4 and CH4/N2 (T  =  298 K). The effects of the changes in interlayer distance were also determined. We show that folding of the walls significantly improves the adsorption and separation properties in comparison to ideal slit-like systems. Moreover, we demonstrate that mutual shift of sheets (for small interlayer distances) causes the appearance of small pores between opposite bulges. This causes an increase in vapour adsorption at low pressures. Due to overlapping of interactions with opposite walls causing an increase in adsorption energy, the mutual shift of sheets is also connected with the rise in efficiency of mixture separation. The effects connected with sheet orientation vanish as the interlayer distance increases. PMID:26569632

  11. Ab Initio Study of Water Adsorption and Reactivity on the (211) Surface of Anatase TiO2

    NASA Astrophysics Data System (ADS)

    Xu, Jing; Xu, Li-Fang; Li, Zhen-Zhen; Wang, Jian-Tao; Lin, Zhe-Shuai; Liu, Kai; Cao, Yong-Ge; Selloni, Annabella

    2016-06-01

    The reactivity of the anatase TiO2 (211) surface is systematically studied by ab initio calculations of the surface energy and water-adsorption energy. We find that anatase (211) has a high surface energy of 0.97 J /m2 , close to that of the (001) surface, and the unsaturated fourfold-coordinated Ti4 atom is more reactive than the unsaturated fivefold-coordinated Ti5 atom. Accordingly, for water adsorption on the (211) surface, a dissociative form is favored on Ti4 sites, with a large adsorption energy Δ HH ,OH˜1.28 eV , while a nondissociative molecular form is favored on Ti5 sites, with a smaller adsorption energy Δ HH2O˜0.78 eV . Such distinct surface properties lead to a mixed dissociative and molecular adsorption configuration when the coverage is increased from 1 /3 to 1 monolayer. These results suggest that, similar to the (001) surface, the anatase (211) surface exhibits high reactivity and may be useful in catalytic and photocatalytic applications as well.

  12. Increased hematocrit after applications of conducted energy weapons (including TASER(®) devices) to Sus scrofa.

    PubMed

    Jauchem, James R

    2011-01-01

    Conducted energy weapons (CEWs) are used by law enforcement personnel to incapacitate individuals quickly and effectively, without intending to cause lethality. CEWs have been deployed for relatively long or repeated exposures in some cases. In laboratory animal models, central venous hematocrit has increased significantly after CEW exposure. Even limited applications (e.g., three 5-sec applications) resulted in statistically significant increases in hematocrit. Preexposure hematocrit was significantly higher in nonsurvivors versus survivors after more extreme CEW applications. The purpose of this technical note is to address specific questions that may be generated when examining these results. Comparisons among results of CEW applications, other electrical muscle stimulation, and exercise/voluntary muscle contraction are included. The anesthetized swine appears to be an acceptable animal model for studying changes in hematocrit and associated red blood cell changes. Potential detrimental effects of increased hematocrit, and considerations during law enforcement use, are discussed. PMID:21198623

  13. A switch from white to brown fat increases energy expenditure in cancer-associated cachexia.

    PubMed

    Petruzzelli, Michele; Schweiger, Martina; Schreiber, Renate; Campos-Olivas, Ramon; Tsoli, Maria; Allen, John; Swarbrick, Michael; Rose-John, Stefan; Rincon, Mercedes; Robertson, Graham; Zechner, Rudolf; Wagner, Erwin F

    2014-09-01

    Cancer-associated cachexia (CAC) is a wasting syndrome characterized by systemic inflammation, body weight loss, atrophy of white adipose tissue (WAT) and skeletal muscle. Limited therapeutic options are available and the underlying mechanisms are poorly defined. Here we show that a phenotypic switch from WAT to brown fat, a phenomenon termed WAT browning, takes place in the initial stages of CAC, before skeletal muscle atrophy. WAT browning is associated with increased expression of uncoupling protein 1 (UCP1), which uncouples mitochondrial respiration toward thermogenesis instead of ATP synthesis, leading to increased lipid mobilization and energy expenditure in cachectic mice. Chronic inflammation and the cytokine interleukin-6 increase UCP1 expression in WAT, and treatments that reduce inflammation or β-adrenergic blockade reduce WAT browning and ameliorate the severity of cachexia. Importantly, UCP1 staining is observed in WAT from CAC patients. Thus, inhibition of WAT browning represents a promising approach to ameliorate cachexia in cancer patients. PMID:25043816

  14. Disruption of the Class IIa HDAC Corepressor Complex Increases Energy Expenditure and Lipid Oxidation.

    PubMed

    Gaur, Vidhi; Connor, Timothy; Sanigorski, Andrew; Martin, Sheree D; Bruce, Clinton R; Henstridge, Darren C; Bond, Simon T; McEwen, Kevin A; Kerr-Bayles, Lyndal; Ashton, Trent D; Fleming, Cassandra; Wu, Min; Pike Winer, Lisa S; Chen, Denise; Hudson, Gregg M; Schwabe, John W R; Baar, Keith; Febbraio, Mark A; Gregorevic, Paul; Pfeffer, Frederick M; Walder, Ken R; Hargreaves, Mark; McGee, Sean L

    2016-09-13

    Drugs that recapitulate aspects of the exercise adaptive response have the potential to provide better treatment for diseases associated with physical inactivity. We previously observed reduced skeletal muscle class IIa HDAC (histone deacetylase) transcriptional repressive activity during exercise. Here, we find that exercise-like adaptations are induced by skeletal muscle expression of class IIa HDAC mutants that cannot form a corepressor complex. Adaptations include increased metabolic gene expression, mitochondrial capacity, and lipid oxidation. An existing HDAC inhibitor, Scriptaid, had similar phenotypic effects through disruption of the class IIa HDAC corepressor complex. Acute Scriptaid administration to mice increased the expression of metabolic genes, which required an intact class IIa HDAC corepressor complex. Chronic Scriptaid administration increased exercise capacity, whole-body energy expenditure and lipid oxidation, and reduced fasting blood lipids and glucose. Therefore, compounds that disrupt class IIa HDAC function could be used to enhance metabolic health in chronic diseases driven by physical inactivity. PMID:27626651

  15. Energy Dense, Protein Restricted Diet Increases Adiposity and Perturbs Metabolism in Young, Genetically Lean Pigs

    PubMed Central

    Fisher, Kimberly D.; Scheffler, Tracy L.; Kasten, Steven C.; Reinholt, Brad M.; van Eyk, Gregory R.; Escobar, Jeffery; Scheffler, Jason M.; Gerrard, David E.

    2013-01-01

    Animal models of obesity and metabolic dysregulation during growth (or childhood) are lacking. Our objective was to increase adiposity and induce metabolic syndrome in young, genetically lean pigs. Pre-pubertal female pigs, age 35 d, were fed a high-energy diet (HED; n = 12), containing 15% tallow, 35% refined sugars and 9.1–12.9% crude protein, or a control corn-based diet (n = 11) with 12.2–19.2% crude protein for 16 wk. Initially, HED pigs self-regulated energy intake similar to controls, but by wk 5, consumed more (P<0.001) energy per kg body weight. At wk 15, pigs were subjected to an oral glucose tolerance test (OGTT); blood glucose increased (P<0.05) in control pigs and returned to baseline levels within 60 min. HED pigs were hyperglycemic at time 0, and blood glucose did not return to baseline (P = 0.01), even 4 h post-challenge. During OGTT, glucose area under the curve (AUC) was higher and insulin AUC was lower in HED pigs compared to controls (P = 0.001). Chronic HED intake increased (P<0.05) subcutaneous, intramuscular, and perirenal fat deposition, and induced hyperglycemia, hypoinsulinemia, and low-density lipoprotein hypercholesterolemia. A subset of HED pigs (n = 7) was transitioned back to a control diet for an additional six weeks. These pigs were subjected to an additional OGTT at 22 wk. Glucose AUC and insulin AUC did not improve, supporting that dietary intervention was not sufficient to recover glucose tolerance or insulin production. These data suggest a HED may be used to increase adiposity and disrupt glucose homeostasis in young, growing pigs. PMID:23991090

  16. Tailoring graphene-based electrodes from semiconducting to metallic to increase the energy density in supercapacitors.

    PubMed

    Vatamanu, Jenel; Ni, Xiaojuan; Liu, Feng; Bedrov, Dmitry

    2015-11-20

    The semiconducting character of graphene and some carbon-based electrodes can lead to noticeably lower total capacitances and stored energy densities in electric double layer (EDL)capacitors. This paper discusses the chemical and electronic structure modifications that enhance the available energy bands, density of states and quantum capacitance of graphene substrates near the Fermi level, therefore restoring the conducting character of these materials. The doping of graphene with p or n dopants, such as boron and nitrogen atoms, or the introduction of vacancy defects that introduce zigzag edges, can significantly increase the quantum capacitance within the potential range of interest for the energy storage applications by either shifting the Dirac point away from the Fermi level or by eliminating the Dirac point. We show that a combination of doping and vacancies at realistic concentrations is sufficient to increase the capacitance of a graphene-based electrode to within 1 μF cm(−2) from that of a metallic surface.Using a combination of ab initio calculations and classical molecular dynamics simulations we estimate how the changes in the quantum capacitance of these electrode materials affect the total capacitance stored by the open structure EDL capacitors containing room temperature ionic liquid electrolytes. PMID:26511198

  17. The Adsorption of Polyatomic Molecules on Carbon Surfaces

    NASA Astrophysics Data System (ADS)

    Burde, Jared T.

    our collaborators. As a result of this project, we have gained a better understanding of the kinetics of adsorption. We have learned about the equilibration process of dimers on carbon nanotube bundles, identifying the "filling effect", which increases the rate of total uptake, and explaining the cause of the transient "overshoot" in the coverage of the surface. We also measured the kinetic effect of particle-particle interactions between neighboring adsorbates on the lattice. For our simulations of monomers adsorbing on graphite, we succeeded in developing an analytical equation to predict the characteristic time as a function of chemical potential and of the adsorption and interaction energies of the system. We were able to further explore the processes of adsorption of dimers and trimers on graphite (again observing the filling effect and the overshoot). Finally, we were able to show that the kinetic behaviors of monomers, dimers, and trimers that have been reported in experimental results also arise organically from our model and simulations.

  18. Adsorption kinetics of diatomic molecules.

    PubMed

    Burde, Jared T; Calbi, M Mercedes

    2014-05-01

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

  19. Energy Management Challenges and Opportunities with Increased Intermittent Renewable Generation on the California Electrical Grid

    NASA Astrophysics Data System (ADS)

    Eichman, Joshua David

    Renewable resources including wind, solar, geothermal, biomass, hydroelectric, wave and tidal, represent an opportunity for environmentally preferred generation of electricity that also increases energy security and independence. California is very proactive in encouraging the implementation of renewable energy in part through legislation like Assembly Bill 32 and the development and execution of Renewable Portfolio Standards (RPS); however renewable technologies are not without challenges. All renewable resources have some resource limitations, be that from location, capacity, cost or availability. Technologies like wind and solar are intermittent in nature but represent one of the most abundant resources for generating renewable electricity. If RPS goals are to be achieved high levels of intermittent renewables must be considered. This work explores the effects of high penetration of renewables on a grid system, with respect to resource availability and identifies the key challenges from the perspective of the grid to introducing these resources. The HiGRID tool was developed for this analysis because no other tool could explore grid operation, while maintaining system reliability, with a diverse set of renewable resources and a wide array of complementary technologies including: energy efficiency, demand response, energy storage technologies and electric transportation. This tool resolves the hourly operation of conventional generation resources (nuclear, coal, geothermal, natural gas and hydro). The resulting behavior from introducing additional renewable resources and the lifetime costs for each technology is analyzed.

  20. Factors affecting the adsorption of chromium (VI) on activated carbon

    SciTech Connect

    Yavuz, R.; Orbak, I.; Karatepe, N.

    2006-09-15

    The aim of this investigation was to determine the adsorption behavior of chromium (VI) on two different activated carbon samples produced from Tuncbilek lignite. The effects of the initial chromium (VI) concentration (250-1000 mg/L), temperature (297-323 K) and pH (2.0-9.5) on adsorption were investigated systematically. The effectiveness of the parameters on chromium adsorption was found to be in the order of pH, the initial Cr(VI) concentration and the temperature. Increasing the pH from 2.0 to 9.5 caused a decrease in adsorption. However, the adsorption was increased by increasing the initial Cr(VI) concentration and temperature. The multilinear mathematical model was also developed to predict the Cr(VI) adsorption on activated carbon samples within the experimental conditions.

  1. Capsaicin increases sensation of fullness in energy balance, and decreases desire to eat after dinner in negative energy balance.

    PubMed

    Janssens, Pilou L H R; Hursel, Rick; Westerterp-Plantenga, Margriet S

    2014-06-01

    Addition of capsaicin (CAPS) to the diet has been shown to increase satiety; therefore, CAPS is of interest for anti-obesity therapy. We investigated the effects of CAPS on appetite profile and ad libitum energy intake in relation to energy balance. Fifteen subjects (seven women and eight men, age: 29.7 ± 10.8yrs, BMI: 23.3 ± 2.9 kg/m(2)) underwent four conditions in a randomized crossover design in 36 hour sessions in a respiration chamber; they received 100% of their daily energy requirements in the conditions "100%Control" and "100%CAPS", and 75% of their daily energy requirements in the conditions "75%Control" and "75%CAPS", followed by an ad libitum dinner. In the 100%CAPS and 75%CAPS conditions, CAPS was given at a dose of 2.56 mg (1.03 g of red chili pepper, 39,050 Scoville heat units) with every meal. Satiety (P < 0.05) and fullness (P = 0.01) were measured every waking hour and before and after every meal using visual analogue scales, and were higher in the 100%CAPS versus 100%Control condition. After dinner desire to eat, satiety and fullness did not differ between 75%CAPS and 100%Control, while desire to eat was higher (P < 0.05) and satiety (P = 0.06) and fullness (P = 0.06) tended to be lower in the 75%Control versus 100%Control condition. Furthermore, ad libitum intake (P = 0.07) and overconsumption (P = 0.06) tended to decrease in 100%CAPS versus 100%Control. In energy balance, addition of capsaicin to the diet increases satiety and fullness, and tends to prevent overeating when food intake is ad libitum. After dinner, capsaicin prevents the effects of the negative energy balance on desire to eat. PMID:24630935

  2. Adsorption and plasma-catalytic oxidation of acetone over zeolite-supported silver catalyst

    NASA Astrophysics Data System (ADS)

    Trinh, Quang Hung; Sanjeeva Gandhi, M.; Mok, Young Sun

    2015-01-01

    The abatement of acetone using a combination of non-thermal plasma, catalysis and adsorption was investigated in a dielectric barrier discharge plasma reactor packed with silver-coated zeolite pellets serving as both adsorbent and catalyst. The removal of acetone in this reactor system was carried out by cyclic operation comprising two repetitive steps, namely, adsorption followed by plasma-catalytic oxidation. The effects of the zeolite-supported silver catalyst on the reduction of unwanted ozone emission and the behavior for the formation of gaseous byproducts were examined. The experimental results showed that the zeolite-supported catalyst had a high acetone adsorption capacity of 1.07 mmol g-1 at 25 °C. Acetone with a concentration of 300 ppm was removed from the gas stream and enriched on the zeolite surface during the adsorption step of the cyclic process (100 min). In the succeeding step, the adsorbed acetone was plasma-catalytically treated under oxygen-flowing atmosphere to recover the adsorption capability of the surface. The plasma-catalytic oxidation of the acetone adsorbed in the previous 100 min adsorption step was completed in 15 min. The abatement of acetone by the cyclic adsorption and plasma-catalytic oxidation process was able to increase the performance of the reactor with respect to the energy efficiency, compared to the case of continuous plasma-catalytic treatment. The use of the zeolite-supported silver catalyst largely decreased the emission of unreacted ozone and increased the amount of gaseous byproducts such as carbon oxides and aldehydes due to the enhanced oxidation of the adsorbed acetone and intermediates.

  3. Adsorption of nisin and pediocin on nanoclays.

    PubMed

    Meira, Stela Maris Meister; Jardim, Arthur Izé; Brandelli, Adriano

    2015-12-01

    Three different nanoclays (bentonite, octadecylamine-modified montmorillonite and halloysite) were studied as potential carriers for the antimicrobial peptides nisin and pediocin. Adsorption occurred from peptide solutions in contact with nanoclays at room temperature. Higher adsorption of nisin and pediocin was obtained on bentonite. The antimicrobial activity of the resultant bacteriocin-nanoclay systems was analyzed using skimmed milk agar as food simulant and the largest inhibition zones were observed against Gram-positive bacteria for halloysite samples. Bacteriocins were intercalated into the interlayer space of montmorillonites as deduced from the increase of the basal spacing measured by X-ray diffraction (XRD) assay. Infrared spectroscopy suggested non-electrostatic interactions, such as hydrogen bonding between siloxane groups from clays and peptide molecules. Transmission electron microscopy did not show any alteration in morphologies after adsorption of antimicrobial peptides on bentonite and halloysite. These results indicate that nanoclays, especially halloysite, are suitable nanocarriers for nisin and pediocin adsorption. PMID:26041178

  4. Adsorption of sulfur dioxide by native clinoptilolite

    SciTech Connect

    Merkun, I.I.; Kel'tsev, N.V.; Bratchuk, F.N.; Rogovik, M.I.

    1982-11-10

    The purpose of the present work was to study the adsorption capacity of the little-studied native clinoptilolite from Beregovo in the Zakarpatskaya region (Ruthenia) for sulfur dioxide. Adsorption of SO/sub 2/ under analogous conditions by Patrick's silica gel, prepared by us by a known method, was studied for comparison. Results indicated that native clinoptilolite studied has much higher adsorption capacity than Patrick's silica gel for sulfur dioxide in the temperature range studied. The adsorption capacity of this zeolite alters little with increase of temperature in the range 25-75/sup 0/. It is considered that native clinoptilolite can be used for removing sulfur dioxide from waste gases in the temperature and pressure ranges studied.

  5. Increased energy harvesting and reduced accelerative load for backpacks via frequency tuning

    NASA Astrophysics Data System (ADS)

    Xie, Longhan; Cai, Mingjing

    2015-06-01

    In this research, a backpack-based frequency-tuneable harvesting device was developed to harvest part of the human kinetic energy during walking and to relieve part of the accelerative load of the backpack from the bearer. The harvester employed a tuning mechanism to adjust the stretch ratio of the springs to adjust the system's stiffness so that the harvesting device can work in an appropriate status to generate more power and relieve a greater load from the bearer. The analysis indicates that adjusting the stiffness harvesting system to fit well with various external excitation conditions, can not only achieve more power output but also relieve part of the accelerative load from the bearer; and the experimental results agreed with the simulation. Compared with previous work, the harvester in this work had a higher efficiency in energy harvesting and could relieve an increased accelerative load from the bearer.

  6. Decrease of energy expenditure causes weight increase in olanzapine treatment - a case study.

    PubMed

    Virkkunen, M; Wahlbeck, K; Rissanen, A; Naukkarinen, H; Franssila-Kallunki, A

    2002-05-01

    The aim of this study was to evaluate the mechanisms underlying weight gain induced by the atypical antipsychotic, olanzapine. We performed euglycemic, hyperinsulinemic clamp combined with indirect calorimetry on a 48-year-old male with antisocial personality disorder, alcohol dependence and paranoid ideation before and after one month of olanzapine (10 - 15 mg/day) therapy. The patient gave his informed, written consent for this study. The results were a weight gain of 6 kg and a decrease in both basal (from 1673 to 1613 kcal/24 h) and 3-hour (from 22.8 to 20.2 cal/kg fat free mass/min) energy expenditure. Serum thyroid hormone and high-density lipoprotein cholesterol levels decreased, and the triglyceride and low-density lipoprotein cholesterol levels increased. Insulin sensitivity did not change. We conclude that decreased basal energy expenditure may contribute to weight gain in olanzapine treatment. PMID:12107860

  7. Increasing Energy-harvesting ability of piezoelectric unimorph cantilevers using Spring Supports

    NASA Astrophysics Data System (ADS)

    Kim, Kyung Bum; Nahm, San; Sung, Tae Hyun; Paik, Jong Hoo; Kim, Hyoung Jae

    2016-06-01

    We fabricated a spring-supported piezoelectric unimorph cantilever (SPUC) with enhanced energy-harvesting characteristics by using a 0.69Pb(Zr0.47Ti0.53)O3-0.31Pb(Ni0.6Zn0.4)1/3Nb2/3)O3 + CuO (0.5 mol%) thick film sintered at 950 °C; a spring having a spring constant of 14,320 N/m was used as the cantilever support. The SPUC could generate an output power as high as 29 mW with a spring constant of 14,320 N/m across a resistance of 150 kΩ; this corresponded to a power density of 34 mW/cm3. We, therefore, that the thus-fabricated SPUCs when supported by a spring can harvest increased levels of energy.

  8. First principles calculations of the Sc adsorption on Si(001)-c(2 × 4)

    NASA Astrophysics Data System (ADS)

    Romero, M. T.; Cocoletzi, Gregorio H.; Takeuchi, Noboru

    2012-09-01

    We have investigated the energetics and the atomic structure of the adsorption of Sc on the Si(001)-c(2 × 4) surface using first principles total energy calculations, within the periodic density functional. The Sc adsorption has been studied at high symmetry sites considering different concentrations. We have first explored the one atom case and then increased the coverage up to a 0.25 of a monolayer of Sc. For the adsorption of one Sc atom we have obtained that the most stable configuration corresponds to the adsorption in the trench between two Si dimers, at the C1 (cave) site. The interaction of the adsorbed Sc with the Si dimers induces a decrease of the dimers buckling amplitude. On the other hand Si dimers without interaction with the adsorbate have buckling amplitudes similar to those of the clean Si surface. When the Sc coverage is increased to two Sc atoms, the most stable structure corresponds to the adsorption at two consecutive V (valley-bridge) sites along the trench between Si dimers, resulting in the weakening of some of the Si dimers bonds. This result indicates that the formation of one dimensional Sc chains on the silicon surface is energetically and kinetically favorable.

  9. Influence of rhamnolipids and Triton X-100 on adsorption of phenol by Penicillium simplicissimum.

    PubMed

    Liu, Zhifeng; Zeng, Zhuotong; Zeng, Guangming; Li, Jianbing; Zhong, Hua; Yuan, Xingzhong; Liu, Yang; Zhang, Jiachao; Chen, Ming; Liu, Yuanyuan; Xie, Gengxin

    2012-04-01

    The effects of rhamnolipids and Triton X-100 on phenol adsorption by Penicillium simplicissimum were studied. The optimum pH was 7 for phenol adsorption by all the test biomasses. The adsorption of phenol at pH 7 by biomass pre-treated with 0.05% Triton X-100, 0.2% Triton X-100, 0.05% rhamnolipids and 0.005% rhamnolipids was 3.4, 2.7, 2.4, and 1.8-fold, respectively, that of untreated biomass. The pseudo-second-order model and the Freundlich isotherms described the adsorption processes better than the pseudo-first-order model and the Langmuir isotherms, respectively. The pre-treatments by surfactants increased the zeta potential and hydrophobicity of P. simplicissimum. Analysis of the cell surface by Fourier transform infrared spectrometry, energy dispersive X-ray, and environmental scanning electron microscopy indicated that the pre-treatments by surfactants changed the cell surface functional groups, element concentrations and micrographs. The results indicated that surfactants can be potentially used to increase phenol adsorption. PMID:22326331

  10. Increasing serotonin concentrations alter calcium and energy metabolism in dairy cows.

    PubMed

    Laporta, Jimena; Moore, Spencer A E; Weaver, Samantha R; Cronick, Callyssa M; Olsen, Megan; Prichard, Austin P; Schnell, Brian P; Crenshaw, Thomas D; Peñagaricano, Francisco; Bruckmaier, Rupert M; Hernandez, Laura L

    2015-07-01

    A 4×4 Latin square design in which varied doses (0, 0.5, 1.0, and 1.5 mg/kg) of 5-hydroxy-l-tryptophan (5-HTP, a serotonin precursor) were intravenously infused into late-lactation, non-pregnant Holstein dairy cows was used to determine the effects of serotonin on calcium and energy metabolism. Infusion periods lasted 4 days, with a 5-day washout between periods. Cows were infused at a constant rate for 1 h each day. Blood was collected pre- and 5, 10, 30, 60, 90, and 120 min post-infusion, urine was collected pre- and post-infusion, and milk was collected daily. All of the 5-HTP doses increased systemic serotonin as compared to the 0 mg/kg dose, and the 1.0 and 1.5 mg/kg doses increased circulating glucose and non-esterified fatty acids (NEFA) and decreased beta-hydroxybutyrate (βHBA) concentrations. Treatment of cows with either 1.0 or 1.5 mg/kg 5-HTP doses decreased urine calcium elimination, and the 1.5 mg/kg dose increased milk calcium concentrations. No differences were detected in the heart rates, respiration rates, or body temperatures of the cows; however, manure scores and defecation frequency were affected. Indeed, cows that received 5-HTP defecated more, and the consistency of their manure was softer. Treatment of late-lactation dairy cows with 5-HTP improved energy metabolism, decreased loss of calcium into urine, and increased calcium secretion into milk. Further research should target the effects of increasing serotonin during the transition period to determine any benefits for post-parturient calcium and glucose metabolism. PMID:26099356

  11. Adsorption of sulfonamides on reduced graphene oxides as affected by pH and dissolved organic matter.

    PubMed

    Liu, Fei-Fei; Zhao, Jian; Wang, Shuguang; Xing, Baoshan

    2016-03-01

    With the significant increase in use and application of graphene and the frequent presence of sulfonamides (SAs) in water environments, their interactions have attracted extensive attention. In this study, adsorption of two selected SAs (sulfapyridine and sulfathiazole) by two reduced graphene oxides (rGO1 and rGO2) was examined as affected by pH and dissolved organic matter (DOM). Adsorption of SAs by rGOs was highly pH-dependent, and adsorption affinity of different SAs species followed the order of SA(0) > SA(+) > SA(-). The contribution of SA(0) to the overall adsorption was greater than its species fraction, implying the importance of the neutral species to adsorption. SAs adsorption isotherms at three selected pHs were in the order of pH 5.0 > pH 1.0 > pH 11.0, which was in accordance with the variation of site energy distribution analysis. Hydrophobic interaction, π-π EDA interaction and electrostatic interaction were the main mechanisms responsible for SAs adsorption by rGOs. Three representative natural DOMs including humic acid (HA), bovine serum albumin (BSA), and sodium alginate together with sodium dodecylbenzenesulfonate (SDBS) as a synthetic DOM were used to investigate their effect on SAs adsorption. The inhibition impact of DOM on SAs adsorption was lower for rGOs compared with carbon nanotubes and graphite, which might be attributed to the higher oxygen contents of rGOs. Also, the suppression effect of DOM generally followed an order of SDBS > HA ≥ BSA > alginate, indicating the importance role of DOM compositions. These results should be important for assessing the fate and transport of graphene and antibiotics in the environment. PMID:26708762

  12. Hybrid adsorptive membrane reactor

    DOEpatents

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

    2011-03-01

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

  13. 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.

  14. Soil disturbance as a driver of increased stream salinity in a semiarid watershed undergoing energy development

    NASA Astrophysics Data System (ADS)

    Bern, Carleton R.; Clark, Melanie L.; Schmidt, Travis S.; Holloway, JoAnn M.; McDougal, Robert R.

    2015-05-01

    Salinization is a global threat to the quality of streams and rivers, but it can have many causes. Oil and gas development were investigated as one of several potential causes of changes in the salinity of Muddy Creek, which drains 2470 km2 of mostly public land in Wyoming, U.S.A. Stream discharge and salinity vary with seasonal snowmelt and define a primary salinity-discharge relationship. Salinity, measured by specific conductance, increased substantially in 2009 and was 53-71% higher at low discharge and 33-34% higher at high discharge for the years 2009-2012 compared to 2005-2008. Short-term processes (e.g., flushing of efflorescent salts) cause within-year deviations from the primary relation but do not obscure the overall increase in salinity. Dissolved elements associated with increased salinity include calcium, magnesium, and sulfate, a composition that points to native soil salts derived from marine shales as a likely source. Potential causes of the salinity increase were evaluated for consistency by using measured patterns in stream chemistry, slope of the salinity-discharge relationship, and inter-annual timing of the salinity increase. Potential causes that were inconsistent with one or more of those criteria included effects from precipitation, evapotranspiration, reservoirs, grazing, irrigation return flow, groundwater discharge, discharge of energy co-produced waters, and stream habitat restoration. In contrast, surface disturbance of naturally salt-rich soil by oil and gas development activities, such as pipeline, road, and well pad construction, is a reasonable candidate for explaining the salinity increase. As development continues to expand in semiarid lands worldwide, the potential for soil disturbance to increase stream salinity should be considered, particularly where soils host substantial quantities of native salts.

  15. Soil disturbance as a driver of increased stream salinity in a semiarid watershed undergoing energy development

    USGS Publications Warehouse

    Bern, Carleton R.; Clark, Melanie L.; Schmidt, Travis S.; Holloway, JoAnn M.; Mcdougal, Robert

    2015-01-01

    Salinization is a global threat to the quality of streams and rivers, but it can have many causes. Oil and gas development were investigated as one of several potential causes of changes in the salinity of Muddy Creek, which drains 2470 km2 of mostly public land in Wyoming, U.S.A. Stream discharge and salinity vary with seasonal snowmelt and define a primary salinity-discharge relationship. Salinity, measured by specific conductance, increased substantially in 2009 and was 53-71% higher at low discharge and 33-34% higher at high discharge for the years 2009-2012 compared to 2005-2008. Short-term processes (e.g., flushing of efflorescent salts) cause within-year deviations from the primary relation but do not obscure the overall increase in salinity. Dissolved elements associated with increased salinity include calcium, magnesium, and sulfate, a composition that points to native soil salts derived from marine shales as a likely source. Potential causes of the salinity increase were evaluated for consistency by using measured patterns in stream chemistry, slope of the salinity-discharge relationship, and inter-annual timing of the salinity increase. Potential causes that were inconsistent with one or more of those criteria included effects from precipitation, evapotranspiration, reservoirs, grazing, irrigation return flow, groundwater discharge, discharge of energy co-produced waters, and stream habitat restoration. In contrast, surface disturbance of naturally salt-rich soil by oil and gas development activities, such as pipeline, road, and well pad construction, is a reasonable candidate for explaining the salinity increase. As development continues to expand in semiarid lands worldwide, the potential for soil disturbance to increase stream salinity should be considered, particularly where soils host substantial quantities of native salts.

  16. Defect-Mediated Lithium Adsorption and Diffusion on Monolayer Molybdenum Disulfide.

    PubMed

    Sun, Xiaoli; Wang, Zhiguo; Fu, Y Q

    2015-01-01

    Monolayer Molybdenum Disulfide (MoS2) is a promising anode material for lithium ion batteries because of its high capacities. In this work, first principle calculations based on spin density functional theory were performed to investigate adsorption and diffusion of lithium on monolayer MoS2 with defects, such as single- and few-atom vacancies, antisite, and grain boundary. The values of adsorption energies on the monolayer MoS2 with the defects were increased compared to those on the pristine MoS2. The presence of defects causes that the Li is strongly bound to the monolayer MoS2 with adsorption energies in the range between 2.81 and 3.80 eV. The donation of Li 2s electron to the defects causes an enhancement of adsorption of Li on the monolayer MoS2. At the same time, the presence of defects does not apparently affect the diffusion of Li, and the energy barriers are in the range of 0.25-0.42 eV. The presence of the defects can enhance the energy storage capacity, suggesting that the monolayer MoS2 with defects is a suitable anode material for the Li-ion batteries. PMID:26692345

  17. Defect-Mediated Lithium Adsorption and Diffusion on Monolayer Molybdenum Disulfide

    PubMed Central

    Sun, Xiaoli; Wang, Zhiguo; Fu, Y. Q.

    2015-01-01

    Monolayer Molybdenum Disulfide (MoS2) is a promising anode material for lithium ion batteries because of its high capacities. In this work, first principle calculations based on spin density functional theory were performed to investigate adsorption and diffusion of lithium on monolayer MoS2 with defects, such as single- and few-atom vacancies, antisite, and grain boundary. The values of adsorption energies on the monolayer MoS2 with the defects were increased compared to those on the pristine MoS2. The presence of defects causes that the Li is strongly bound to the monolayer MoS2 with adsorption energies in the range between 2.81 and 3.80 eV. The donation of Li 2s electron to the defects causes an enhancement of adsorption of Li on the monolayer MoS2. At the same time, the presence of defects does not apparently affect the diffusion of Li, and the energy barriers are in the range of 0.25–0.42 eV. The presence of the defects can enhance the energy storage capacity, suggesting that the monolayer MoS2 with defects is a suitable anode material for the Li-ion batteries. PMID:26692345

  18. Defect-Mediated Lithium Adsorption and Diffusion on Monolayer Molybdenum Disulfide

    NASA Astrophysics Data System (ADS)

    Sun, Xiaoli; Wang, Zhiguo; Fu, Y. Q.

    2015-12-01

    Monolayer Molybdenum Disulfide (MoS2) is a promising anode material for lithium ion batteries because of its high capacities. In this work, first principle calculations based on spin density functional theory were performed to investigate adsorption and diffusion of lithium on monolayer MoS2 with defects, such as single- and few-atom vacancies, antisite, and grain boundary. The values of adsorption energies on the monolayer MoS2 with the defects were increased compared to those on the pristine MoS2. The presence of defects causes that the Li is strongly bound to the monolayer MoS2 with adsorption energies in the range between 2.81 and 3.80 eV. The donation of Li 2s electron to the defects causes an enhancement of adsorption of Li on the monolayer MoS2. At the same time, the presence of defects does not apparently affect the diffusion of Li, and the energy barriers are in the range of 0.25-0.42 eV. The presence of the defects can enhance the energy storage capacity, suggesting that the monolayer MoS2 with defects is a suitable anode material for the Li-ion batteries.

  19. Increasing energy relaxation time of superconducting qubits with nonmagnetic infrared filter and shield

    NASA Astrophysics Data System (ADS)

    Yuhao, Liu; Mengmeng, Li; Dong, Lan; Guangming, Xue; Xinsheng, Tan; Haifeng, Yu; Yang, Yu

    2016-05-01

    One of the primary origins of the energy relaxation in superconducting qubits is the quasiparticle loss. The quasiparticles can be excited remarkably by infrared radiation. In order to minimize the density of quasiparticle and increase the qubit relaxation time, we design and fabricate the infrared filter and shield for superconducting qubits. In comparison with previous filters and shields, a nonmagnetic dielectric is used as the infrared absorbing material, greatly suppressing the background magnetic fluctuations. The filters can be made to impedance-match with other microwave devices. Using the as-fabricated infrared filter and shield, we increased the relaxation time of a transmon qubit from 519 ns to 1125 ns. Project supported by the National Natural Science Foundation of China (Grant Nos. 91321310, 11274156, 11474152, 11474153, 61521001, and 11504165) and the State Key Program for Basic Research of China (Grant Nos. 2011CB922104 and 2011CBA00205).

  20. Rapid increase in prescission GDR {gamma}-ray emission with energy

    SciTech Connect

    Hofman, D.J.; Back, B.B.; Paul, P.

    1995-12-31

    A rapid increase in the emission of prescission giant dipole resonance (GDR) {gamma}-rays with bombarding energy is observed in excited Th and Cf nuclei formed in the reactions {sup 16}O+{sup 20B}Pb and {sup 32}S+{sup nat}W,{sup 208}Pb. This increase begins around E{sub exc} = 40 MeV for the {sup 16}O+{sup 208}Pb reaction and E{sub exc} = 70 MeV for the {sup 32}S-induced reactions. The excess {gamma}-ray yield above these thresholds cannot be described within the standard statistical model. Statistical model calculations which include a temperature dependent nuclear dissipation are able to reproduce simultaneously the observed GDR {gamma}-ray spectra and recently measured evaporation residue across sections.

  1. Microscopic Theory of Hysteretic Hydrogen Adsorption in Nanoporous Materials

    SciTech Connect

    Kang, J.; Wei, S. H.; Kim, Y. H.

    2010-01-01

    Understanding gas adsorption confined in nanoscale pores is a fundamental issue with broad applications in catalysis and gas storage. Recently, hysteretic H{sub 2} adsorption was observed in several nanoporous metal-organic frameworks (MOFs). Here, using first-principles calculations and simulated adsorption/desorption isotherms, we present a microscopic theory of the enhanced adsorption hysteresis of H{sub 2} molecules using the MOF Co(1,4-benzenedipyrazolate) [Co(BDP)] as a model system. Using activated H{sub 2} diffusion along the small-pore channels as a dominant equilibration process, we demonstrate that the system shows hysteretic H{sub 2} adsorption under changes of external pressure. For a small increase of temperature, the pressure width of the hysteresis, as well as the adsorption/desorption pressure, dramatically increases. The sensitivity of gas adsorption to temperature changes is explained by the simple thermodynamics of the gas reservoir. Detailed analysis of transient adsorption dynamics reveals that the hysteretic H{sub 2} adsorption is an intrinsic adsorption characteristic in the diffusion-controlled small-pore systems.

  2. Dengue Virus NS1 Protein Modulates Cellular Energy Metabolism by Increasing Glyceraldehyde-3-Phosphate Dehydrogenase Activity

    PubMed Central

    Allonso, Diego; Andrade, Iamara S.; Conde, Jonas N.; Coelho, Diego R.; Rocha, Daniele C. P.; da Silva, Manuela L.; Ventura, Gustavo T.

    2015-01-01

    ABSTRACT Dengue is one of the main public health concerns worldwide. Recent estimates indicate that over 390 million people are infected annually with the dengue virus (DENV), resulting in thousands of deaths. Among the DENV nonstructural proteins, the NS1 protein is the only one whose function during replication is still unknown. NS1 is a 46- to 55-kDa glycoprotein commonly found as both a membrane-associated homodimer and a soluble hexameric barrel-shaped lipoprotein. Despite its role in the pathogenic process, NS1 is essential for proper RNA accumulation and virus production. In the present study, we identified that glyceraldehyde-3-phosphate dehydrogenase (GAPDH) interacts with intracellular NS1. Molecular docking revealed that this interaction occurs through the hydrophobic protrusion of NS1 and the hydrophobic residues located at the opposite side of the catalytic site. Moreover, addition of purified recombinant NS1 enhanced the glycolytic activity of GAPDH in vitro. Interestingly, we observed that DENV infection promoted the relocalization of GAPDH to the perinuclear region, where NS1 is commonly found. Both DENV infection and expression of NS1 itself resulted in increased GAPDH activity. Our findings indicate that the NS1 protein acts to increase glycolytic flux and, consequently, energy production, which is consistent with the recent finding that DENV induces and requires glycolysis for proper replication. This is the first report to propose that NS1 is an important modulator of cellular energy metabolism. The data presented here provide new insights that may be useful for further drug design and the development of alternative antiviral therapies against DENV. IMPORTANCE Dengue represents a serious public health problem worldwide and is caused by infection with dengue virus (DENV). Estimates indicate that half of the global population is at risk of infection, with almost 400 million cases occurring per year. The NS1 glycoprotein is found in both the

  3. Strengthening of Graphene Aerogels with Tunable Density and High Adsorption Capacity towards Pb2+

    PubMed Central

    Han, Zhuo; Tang, Zhihong; Shen, Shuling; Zhao, Bin; Zheng, Guangping; Yang, Junhe

    2014-01-01

    Graphene aerogels (GAs) with high mechanical strength, tunable density and volume have been prepared only via soaking graphene hydrogels (GHs) in ammonia solution. The density and volume of the obtained GAs are controlled by adjusting the concentration of ammonia solution. Although volume of the GAs decreases with increasing the concentration of ammonia solution, its specific surface area maintains at about 350 m2 g−1, and the inner structure changes to radial after ammonia solution treatment. Thus, GAs are particularly suitable for the adsorption and energy storage applications owing to their high specific surface area and unique porous structure. The adsorption capacity of GAs for Pb2+ from aqueous solution maintains at about 80 mg g−1, which could reach as high as 5000 g m−3 per unit volume and they can be separated easily from water after adsorption. PMID:24848100

  4. Molecular Adsorption Changes the Quantum Structure of Oxide-Supported Gold Nanoparticles: Chemisorption versus Physisorption.

    PubMed

    Stiehler, Christian; Calaza, Florencia; Schneider, Wolf-Dieter; Nilius, Niklas; Freund, Hans-Joachim

    2015-07-17

    STM conductance spectroscopy and mapping has been used to analyze the impact of molecular adsorption on the quantized electronic structure of individual metal nanoparticles. For this purpose, isophorone and CO2, as prototype molecules for physisorptive and chemisorptive binding, were dosed onto monolayer Au islands grown on MgO thin films. The molecules attach exclusively to the metal-oxide boundary, while the interior of the islands remains pristine. The Au quantum well states are perturbed due to the adsorption process and increase their mutual energy spacing in the CO2 case but move together in isophorone-covered islands. The shifts disclose the nature of the molecule-Au interaction, which relies on electron exchange for the CO2 ligands but on dispersive forces for the organic species. Our experiments reveal how molecular adsorption affects individual quantum systems, a topic of utmost relevance for heterogeneous catalysis. PMID:26230817

  5. Thermodynamics and kinetics of adsorption of selected monoalkylbenzenes in H-ZSM-5

    SciTech Connect

    Schumacher, R.; Karge, H.G.

    1999-03-04

    In this study, the authors present the first systematic investigation of the adsorption of n-propylbenzene, isopropylbenzene, and n-butylbenzene in H-ZSM-5. Both the sorption isotherms and the rate of sorption uptake were investigated at temperatures between 315 and 425 K. The adsorption isotherms are of type 1 and are reasonably well described by the Langmuir-Freundlich model. It is shown that the heat of adsorption of the longer sorbate molecules depends significantly on the concentration, thus indicating an increased influence of sorbate-sorbate interaction. The uptake rates are determined by Fickian diffusion. The activation energies for the diffusion process are identical for all systems (32--36 kJ/mol). The diffusivities are also in the same order of magnitude decreasing noticeably for sorbates with longer or more complex substituents. A tentative explanation based on a simple jump-rate model for intracrystalline diffusion is given.

  6. [Characteristic of ammonia nitrogen adsorption on karst underground river sediments].

    PubMed

    Guo, Fang; Chen, Kun-Kun; Jiang, Guang-Hui

    2011-02-01

    Karst aquifers are one of the most important aquifers in Southwestern China. One of the characteristics of karst aquifers is the enhanced permeability permits high flow velocities are capable of transporting suspended and bedload sediments. Mobile sediment in karst may act as a vector for the transport of contaminates. 14 sediment samples were collected from two underground rivers in two typical karst areas in Liuzhou city, Guangxi Autonomous Region, China. According to simulated experiment methods, characteristic of adsorption of ammonia nitrogen on sediment was studied. The results of ammonia nitrogen adsorption dynamics on sediments showed that the maximum adsorption velocity was less than 2 h. The adsorption balance quantity in 5 h accounted for 71% - 98% of the maximum adsorption quantity. The maximum adsorption quantity of ammonia nitrogen was 385.5 mg/kg, which was sediment from a cave in the middle areas of Guancun underground river system. The study of isotherm adsorption indicated adsorption quantity of NH4+ increase followed by incremental balance concentration of NH4+ in the aquatic phase. Adsorption quantity of ammonia nitrogen in sediments has a relative linear relationship with adsorption balance concentrations. Adsorption-desorption balance concentrations were all low, indicating sediments from underground rivers have great adsorption potential. Under the condition of low and high concentrations of ammonia nitrogen in overlying water, Langmuir and Tempkin couldn't simulate or simulate results couldn't reach remarkable level, whilst Linear and Freundlich models could simulate well. Research on different type sediments, sampling times and depths from two underground rivers shows characteristic of ammonia nitrogen adsorption on karst underground river sediments doesn't have good correspondence with the type of sediments. One of the reasons is there is no big difference between sediments in the development of climate, geology, hydrological conditions

  7. Influence of soil solution cation composition on boron adsorption by soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Boron (B) adsorption on five arid-zone soil samples from California was investigated as a function of solution pH (4-10) and cation composition (Na, Ca, or Mg). Boron adsorption increased with increasing solution pH, reached an adsorption maximum near pH 9, and decreased with further increases with...

  8. Adsorption of amino acids by fullerenes and fullerene nanowhiskers

    NASA Astrophysics Data System (ADS)

    Hashizume, Hideo; Hirata, Chika; Fujii, Kazuko; Miyazawa, Kun'ichi

    2015-12-01

    We have investigated the adsorption of some amino acids and an oligopeptide by fullerene (C60) and fullerene nanowhiskers (FNWs). C60 and FNWs hardly adsorbed amino acids. Most of the amino acids used have a hydrophobic side chain. Ala and Val, with an alkyl chain, were not adsorbed by the C60 or FNWs. Trp, Phe and Pro, with a cyclic structure, were not adsorbed by them either. The aromatic group of C60 did not interact with the side chain. The carboxyl or amino group, with the frame structure of an amino acid, has a positive or negative charge in solution. It is likely that the C60 and FNWs would not prefer the charged carboxyl or amino group. Tri-Ala was adsorbed slightly by the C60 and FNWs. The carboxyl or amino group is not close to the center of the methyl group of Tri-Ala. One of the methyl groups in Tri-Ala would interact with the aromatic structure of the C60 and FNWs. We compared our results with the theoretical interaction of 20 bio-amino acids with C60. The theoretical simulations showed the bonding distance between C60 and an amino acid and the dissociation energy. The dissociation energy was shown to increase in the order, Val < Phe < Pro < Asp < Ala < Trp < Tyr < Arg < Leu. However, the simulation was not consistent with our experimental results. The adsorption of albumin (a protein) by C60 showed the effect on the side chains of Try and Trp. The structure of albumin was changed a little by C60. In our study Try and Tyr were hardly adsorbed by C60 and FNWs. These amino acids did not show a different adsorption behavior compared with other amino acids. The adsorptive behavior of mono-amino acids might be different from that of polypeptides.

  9. 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

  10. Electromechanical modeling of a honeycomb core integrated vibration energy converter with increased specific power for energy harvesting applications

    NASA Astrophysics Data System (ADS)

    Chandrasekharan, Nataraj

    Innovation in integrated circuit technology along with improved manufacturing processes has resulted in considerable reduction in power consumption of electromechanical devices. Majority of these devices are currently powered by batteries. However, the issues posed by batteries, including the need for frequent battery recharge/replacement has resulted in a compelling need for alternate energy to achieve self-sufficient device operation or to supplement battery power. Vibration based energy harvesting methods through piezoelectric transduction provides with a promising potential towards replacing or supplementing battery power source. However, current piezoelectric energy harvesters generate low specific power (power-to-weight ratio) when compared to batteries that the harvesters seek to replace or supplement. In this study, the potential of integrating lightweight cellular honeycomb structures with existing piezoelectric device configurations (bimorph) to achieve higher specific power is investigated. It is shown in this study that at low excitation frequency ranges, replacing the solid continuous substrate of a conventional piezoelectric bimorph with honeycomb structures of the same material results in a significant increase in power-to-weight ratio of the piezoelectric harvester. In order to maximize the electrical response of vibration based power harvesters, the natural frequency of these harvesters is designed to match the input driving frequency. The commonly used technique of adding a tip mass is employed to lower the natural frequency (to match driving frequency) of both, solid and honeycomb substrate bimorphs. At higher excitation frequency, the natural frequency of the traditional solid substrate bimorph can only be altered (to match driving frequency) through a change in global geometric design parameters, typically achieved by increasing the thickness of the harvester. As a result, the size of the harvester is increased and can be disadvantageous

  11. The adsorption and inhibition effect of calcium lignosulfonate on Q235 carbon steel in simulated concrete pore solution

    NASA Astrophysics Data System (ADS)

    Wang, Yishan; Zuo, Yu; Zhao, Xuhui; Zha, Shanshan

    2016-08-01

    The corrosion inhibition of calcium lignosulfonate (CLS) for Q235 carbon steel in saturated Ca(OH)2 + 0.1 mol/L NaCl solution was studied by means of weight loss, polarization, fluorescence microscopy (FM), scanning electron microscopy/energy dispersive spectrometry (SEM/EDS), microscopic infrared spectral imaging (M-IR) and X-ray photoelectron spectroscopy (XPS). For the steel in simulated concrete pore solution (pH 12.6), an increase of Eb value and a decrease of icorr value occurred with different concentrations of CLS. The optimal content of CLS was 0.001 mol/L at which the inhibition rate was 98.86% and the Eb value increased to 719 mV after 10 h of immersion. In mortar solution and in reinforced concrete environment, CLS also showed good inhibition for steel. The preferential adsorption of CLS around pits was detected by M-IR. The result illustrates that at the early stage the adsorption of CLS was heterogeneous and CLS may have a competitive adsorption with chloride ions at the active sites, which would be beneficial for decreasing the susceptibility of pitting corrosion. After the pre-filming time, an intact adsorption CLS film formed on carbon steel surface. The adsorption between CLS and calcium presented as Casbnd Osbnd S bonds. The adsorption of CLS on carbon steel surface occurred probably by both physisorption and chemisorption.

  12. Adsorption of gases and vapors on nanoporous Ni2(4,4'-Bipyridine)3(NO3)4 metal-organic framework materials templated with methanol and ethanol: structural effects in adsorption kinetics.

    PubMed

    Fletcher, Ashleigh J; Cussen, Edmund J; Bradshaw, Darren; Rosseinsky, Matthew J; Thomas, K Mark

    2004-08-11

    Desolvation of Ni(2)(4,4'-bipyridine)(3)(NO(3))(4).2CH(3)OH and Ni(2)(4,4'-bipyridine)(3)(NO(3))(4).2C(2)H(5)OH give flexible metal-organic porous structures M and E, respectively, which have the same stoichiometry, but subtly different structures. This study combines measurements of the thermodynamics and kinetics of carbon dioxide, methanol, and ethanol sorption on adsorbents M and E over a range of temperatures with adsorbent structural characterization at different adsorbate (guest) loadings. The adsorption kinetics for methanol and ethanol adsorption on porous structure E obey a linear driving force (LDF) mass transfer model for adsorption at low surface coverage. The corresponding adsorption kinetics for porous structure M follow a double exponential (DE) model, which is consistent with two different barriers for diffusion through the windows and along the pores in the structure. The former is a high-energy barrier due to the opening of the windows in the structure, required to allow adsorption to occur, while the latter is a lower-energy barrier for diffusion in the pore cavities. X-ray diffraction studies at various methanol and ethanol loadings showed that the host porous structures E and M underwent different scissoring motions, leading to an increase in unit cell volume with the space group remaining unchanged during adsorption. The results are discussed in terms of reversible adsorbate/adsorbent (host/guest) structural changes and the adsorption mechanism involving hydrogen-bonding interactions with specific surface sites for methanol and ethanol adsorption in relation to pore size and extent of filling. This paper contains the first evidence for individual kinetic barriers to diffusion through windows and pore cavities in flexible porous coordination polymer frameworks. PMID:15291578

  13. Molecular mechanics modelling and simulation of the adsorption-induced surface stress in micro-nano-cantilever sensors

    NASA Astrophysics Data System (ADS)

    Wu, H. A.; Sun, Z. H.; Cheng, Q.; Wang, X. X.

    2007-04-01

    Micro-nano-cantilevers have the exclusive potential to be an extremely sensitive sensor for chemical and biological detections. The mechanism of the sensor is that the adsorption-induced surface stresses cause the cantilever to bend, which can be measured by electronic or optical methods. In this paper, molecular mechanics method and theoretical energy minimization method are developed to study this bending behaviour. Molecular mechanics simulations were carried out on a homoepitaxy copper nano-cantilever to investigate the dependence of adsorption-induced surface stress on adatom concentration. Noneven pattern of development of adsorption-induced surface stress as adatom concentration increases was observed in the present atomistic simulations. To study the bending of microcantilever induced by adsorption, e.g. mercury adsorption on gold-coated cantilevers, the total energy consisting of atomic interaction energy of elastic bending energy is minimized. The Lennard Jones model is employed to represent the interaction between mercury and gold atoms. Based on Dareinga's model, we developed a model with more atoms and considered the periodic boundary conditions. Calculated deflections with the proposed new model agree better with measured deflection data. This discussion can contribute to our knowledge base about mechanisms of surface stress and micro-nano-cantilever bio-sensor.

  14. Benefits to the United States of Increasing Global Uptake of Clean Energy Technologies

    SciTech Connect

    Kline, D.

    2010-07-01

    A previous report describes an opportunity for the United States to take leadership in efforts to transform the global energy system toward clean energy technologies (CET). An accompanying analysis to that report provides estimates of the economic benefits to the United States of such a global transformation on the order of several hundred billion dollars per year by 2050. This report describes the methods and assumptions used in developing those benefit estimates. It begins with a summary of the results of the analysis based on an updated and refined model completed since the publication of the previous report. The framework described can be used to estimate the economic benefits to the U.S. of coordinated global action to increase the uptake of CETs worldwide. Together with a Monte Carlo simulation engine, the framework can be used to develop plausible ranges for benefits, taking into account the large uncertainty in the driving variables and economic parameters. The resulting estimates illustrate that larger global clean energy markets offer significant opportunities to the United States economy.

  15. Deletion of murine Arv1 results in a lean phenotype with increased energy expenditure

    PubMed Central

    Lagor, W R; Tong, F; Jarrett, K E; Lin, W; Conlon, D M; Smith, M; Wang, M Y; Yenilmez, B O; McCoy, M G; Fields, D W; O'Neill, S M; Gupta, R; Kumaravel, A; Redon, V; Ahima, R S; Sturley, S L; Billheimer, J T; Rader, D J

    2015-01-01

    Background: ACAT-related enzyme 2 required for viability 1 (ARV1) is a putative lipid transporter of the endoplasmic reticulum that is conserved across eukaryotic species. The ARV1 protein contains a conserved N-terminal cytosolic zinc ribbon motif known as the ARV1 homology domain, followed by multiple transmembrane regions anchoring it in the ER. Deletion of ARV1 in yeast results in defective sterol trafficking, aberrant lipid synthesis, ER stress, membrane disorganization and hypersensitivity to fatty acids (FAs). We sought to investigate the role of Arv1 in mammalian lipid metabolism. Methods: Homologous recombination was used to disrupt the Arv1 gene in mice. Animals were examined for alterations in lipid and lipoprotein levels, body weight, body composition, glucose tolerance and energy expenditure. Results: Global loss of Arv1 significantly decreased total cholesterol and high-density lipoprotein cholesterol levels in the plasma. Arv1 knockout mice exhibited a dramatic lean phenotype, with major reductions in white adipose tissue (WAT) mass and body weight on a chow diet. This loss of WAT is accompanied by improved glucose tolerance, higher adiponectin levels, increased energy expenditure and greater rates of whole-body FA oxidation. Conclusions: This work identifies Arv1 as an important player in mammalian lipid metabolism and whole-body energy homeostasis. PMID:26479315

  16. Holographic lens spectrum splitting photovoltaic system for increased diffuse collection and annual energy yield

    NASA Astrophysics Data System (ADS)

    Vorndran, Shelby D.; Wu, Yuechen; Ayala, Silvana; Kostuk, Raymond K.

    2015-09-01

    Concentrating and spectrum splitting photovoltaic (PV) modules have a limited acceptance angle and thus suffer from optical loss under off-axis illumination. This loss manifests itself as a substantial reduction in energy yield in locations where a significant portion of insulation is diffuse. In this work, a spectrum splitting PV system is designed to efficiently collect and convert light in a range of illumination conditions. The system uses a holographic lens to concentrate shortwavelength light onto a smaller, more expensive indium gallium phosphide (InGaP) PV cell. The high efficiency PV cell near the axis is surrounded with silicon (Si), a less expensive material that collects a broader portion of the solar spectrum. Under direct illumination, the device achieves increased conversion efficiency from spectrum splitting. Under diffuse illumination, the device collects light with efficiency comparable to a flat-panel Si module. Design of the holographic lens is discussed. Optical efficiency and power output of the module under a range of illumination conditions from direct to diffuse are simulated with non-sequential raytracing software. Using direct and diffuse Typical Metrological Year (TMY3) irradiance measurements, annual energy yield of the module is calculated for several installation sites. Energy yield of the spectrum splitting module is compared to that of a full flat-panel Si reference module.

  17. New method to increase the energy conversion efficiency of thermoacoustic engine

    NASA Astrophysics Data System (ADS)

    Kido, Aiko; Sakamoto, Shin-ichi; Taga, Kazusa; Watanabe, Yoshiaki

    2015-10-01

    Many researches have been reported to improve an energy conversion efficiency of thermoacoustic engine. Proposed improvement methods by our group were a phase adjuster (PA) and expanding phase adjuster (EPA) devices. They act as the amplifier and stabilizer of the system oscillation. However, there are some problems for these devices. Because of the solidified device and located in the thermoacoustic tube, it is difficult to tune and move them to the best setting position during system operation. Therefore, it is necessary to find more easy methods that produce the same amplifier and stabilizer effects of the PA and EPA. In this report, we propose the local heating method. Experiments are carried out using the loop-tube-type thermoacoustic system. Two electric heaters are set on the system, one is for the PM stack and the other is for the proposed heater HPA. The setting position of the HPA is easily changed, and then the HPA is moved to the various positions from the PM stack along the system. Resonant mode was changed depending on the setting position of HPA. As the result of the change of resonant mode, energy conversion efficiency is also changed. Especially the resonant mode is realized in the single wavelength mode, it is confirmed that, the energy conversion efficiency in substantially increased compare with the system without the HPA. These observed phenomena are similar to the behavior of EPA. Therefore, the presented method can be performed as an easier method to perform a high efficiency and stable oscillation.

  18. Adsorption of Ar on individual carbon nanotubes, graphene, and graphite

    NASA Astrophysics Data System (ADS)

    Dzyubenko, Boris; Kahn, Joshua; Vilches, Oscar; Cobden, David

    2015-03-01

    We compare and contrast results of adsorption measurements of Ar on single-walled carbon nanotubes, graphene, and graphite. Adsorption isotherms on individual suspended nanotubes were obtained using both the mechanical resonance frequency shift (sensitive to mass adsorption) and the electrical conductance. Isotherms on graphene mounted on hexagonal boron nitride were obtained using only the conductance. New volumetric adsorption isotherms on bulk exfoliated graphite were also obtained, paying special attention to the very low coverage region (less than 2% of a monolayer). This allowed us to compare the degree of heterogeneity on the three substrate types, the binding energies, and the van der Waals 2D parameters. Research supported by NSF DMR 1206208.

  19. Kaempferia parviflora extract increases whole-body energy expenditure in humans: roles of brown adipose tissue.

    PubMed

    Matsushita, Mami; Yoneshiro, Takeshi; Aita, Sayuri; Kamiya, Tomoyasu; Kusaba, Nobutaka; Yamaguchi, Kazuya; Takagaki, Kinya; Kameya, Toshimitsu; Sugie, Hiroki; Saito, Masayuki

    2015-01-01

    Kaempferia parviflora extract (KP) has been reported to have a preventive effect on obesity in mice, probably by increasing energy expenditure (EE). The aims of the current study were to examine the acute effects of KP ingestion on whole-body EE in humans and to analyze its relation to the activity of brown adipose tissue (BAT), a site of non-shivering thermogenesis. After an oral ingestion of an ethanol extract of KP, EE increased significantly, showing a maximal increase of 229±69 kJ/d at 60 min, while it did not change after placebo ingestion. To evaluate BAT activity, the subjects underwent fluorodeoxyglucose-positron emission tomography, and divided into two groups with high- and low-BAT activities. A similar and greater response of EE to KP ingestion was observed in the high-BAT group (351±50 kJ/d at 60 min), but not in the low activity group. Placebo ingestion did not cause any significant EE change in either group. These results indicate that a single oral ingestion of the KP extract can potentially increase whole-body EE probably through the activation of BAT in healthy men, and may be useful as an anti-obesity regimen. PMID:25994142

  20. Equilibrium and kinetics studies of arsenate adsorption by FePO(4).

    PubMed

    Hamayun, M; Mahmood, T; Naeem, A; Muska, M; Din, S U; Waseem, M

    2014-03-01

    The present work is focusing on removal of arsenate from aqueous solution using FePO4. The equilibrium study regarding the removal of arsenic by FePO4 was carried out at 298, 308, 318 and 328K. Langmuir parameters were found to increase with the increase in temperature indicating that the adsorption is favorable at high temperature. Kinetic study of arsenate adsorption on FePO4 was also carried out at different temperatures and at pH 6 and 8. Different kinetic models were used to the kinetic data amongst which pseudo second order model was best fitted. The mechanism of the adsorption kinetics was investigated by employing intraparticle diffusion and Richenberg models. The energy of activation (Ea) was found to be 30 and 35.52kJmol(-1) at pH 6 and pH 8, respectively, suggesting chemisorption nature of the adsorption process. The negative entropic values of activation signified the existence of entropy barrier while the positive ΔG(#) values indicated the existence of energy barrier to be crossed over for the occurrence of a chemical reaction. Both the spectroscopic studies and increase in equilibrium pH reveal the anion exchange removal of arsenate from aqueous solution to the solid surface. PMID:24280053

  1. Coral mortality increases wave energy reaching shores protected by reef flats: Examples from the Seychelles

    NASA Astrophysics Data System (ADS)

    Sheppard, Charles; Dixon, David J.; Gourlay, Michael; Sheppard, Anne; Payet, Rolph

    2005-08-01

    In the granitic Seychelles, many shores and beaches are fringed by coral reef flats which provide protection to shores from erosion by waves. The surfaces of these reef flats support a complex ecology. About 10 years ago their seaward zones were extensively covered by a rich coral growth, which reached approximately to mean low water level, but in 1998 this was largely killed by seawater warming. The resulting large expanses of dead coral skeletons in these locations are now disintegrating, and much of the subsequent modest recovery by new coral recruitment was set back by further mortalities. A mathematical model of wave energy reaching shorelines protected by coral reef flats has been applied to 14 Seychelles reefs. It is derived from equations which predict: (1) the raised water level, or wave set-up, on reef flats resulting from wave breaking, which depends upon offshore wave height and period, depth of still water over the reef flat and the reef crest profile, and (2) the decay of energy from reef edge to shoreline that is affected by width of reef flat, surface roughness, sea level rise and 'pseudo-sea level rise' created by increased depth resulting from disintegration of coral colonies. The model treats each reef as one entity, but because biota and zonation on reef flats are not homogenous, all reefs are divided into four zones. In each, cover by both living and dead biota was estimated for calculation of parameters, and then averaged to obtain input data for the model. All possible biological factors were taken into account, such as the ability of seagrass beds to grow upwards to match expected sea level rise, reduction in height of the reef flat in relation to sea level as zones of dead corals decay, and the observed 'rounding' of reef crests as erosion removes corals from those areas. Estimates were also made of all these factors for a time approximately a decade ago, representing a time before the mass coral mortality, and for approximately a decade in

  2. A Strategy to Increase Microbial Hydrogen Production, Facilitating Intracellular Energy Reserves.

    PubMed

    Lee, Hyo Jung; Park, Jihoon; Lee, Joo-Young; Kim, Pil

    2016-08-28

    Overexpression of the genes encoding phosphoeneolpyruvate carboxykinase (pckA) and NAD-dependent malic enzyme (maeA) facilitates higher intracellular ATP and NAD(P)H concentrations, respectively, under aerobic conditions in Escherichia coli. To verify a hypothesis that higher intracellular energy reserves might contribute to H2 fermentation, wild-type E. coli strains overexpressing pckA and maeA were cultured under anaerobic conditions in a glucose minimal medium. Overexpression of pckA and maeA enabled E. coli to produce 3- times and 4-times greater H2 (193 and 284 nmol, respectively) than the wild type (66 nmol H2). The pckA and maeA genes were further overexpressed in a hydrogenase-3-enhanced E. coli strain. The hydrogenase-3-enhanced strain (W3110+fhlA) produced 322 nmol H2, whereas the ATP-enhanced strain (W3110+fhlA+pckA) produced 50% increased H2 (443 nmol). Total H2 in the NAD(P)H-enhanced strain (W3110+fhlA+maeA) was similar to that in the control strain at 319 nmol H2. Possible explanations for the contribution of the increased cellular energy reserves to the enhanced hydrogen fermentation observed are discussed based on the viewpoint of metabolic engineering strategy. PMID:27116993

  3. Simulated Water Adsorption Isotherms in Hydrophilic and Hydrophobic Cylinderical Nanopores

    SciTech Connect

    StrioloDr., A; Naicker, P. K.; Chialvo, Ariel A; Cummings, Peter T; Gubbins, Dr. K. E.

    2005-01-01

    Grand canonical Monte Carlo simulations are performed to study the adsorption of water in single-walled carbon nanotubes (SWCNs). At room temperature the resulting adsorption isotherms in (10:10) and wider SWCNs are characterized by negligible amount of water uptake at low pressures, sudden and complete pore filling once a threshold pressure is reached, and wide adsorption/desorption hysteresis loops. The width of these loops decreases as pore diameter narrows. Adsorption/desorption hysteresis loops are not observed for water adsorption in (6:6) SWCNs. When the nanotubes are doped with small amounts of oxygenated sites it is possible to obtain adsorption isotherms in which the water uptake increases gradually as the pressure increases. Simulated X-ray diffraction patterns for confined water are also reported.

  4. Adsorptive Removal and Adsorption Kinetics of Fluoroquinolone by Nano-Hydroxyapatite

    PubMed Central

    Chen, Yajun; Lan, Tao; Duan, Lunchao; Wang, Fenghe; Zhao, Bin; Zhang, Shengtian; Wei, Wei

    2015-01-01

    Various kinds of antibiotics, especially fluoroquinolone antibiotics (FQs) have been widely used for the therapy of infectious diseases in human and livestock. For their poorly absorbed by living organisms, large-scale misuse or abuse of FQs will foster drug resistance among pathogenic bacteria, as well as a variety of environmental problems when they were released in the environment. In this work, the adsorption properties of two FQs, namely norfloxacin (NOR) and ciprofloxacin (CIP), by nano-hydroxyapatite (n-HAP) were studied by batch adsorption experiments. The adsorption curves of FQs by n-HAP were simulated by Langmuir and Freundlich isotherms. The results shown that NOR and CIP can be adsorbed effectively by the adsorbent of n-HAP, and the adsorption capacity of FQs increase with increasing dosage of n-HAP. The optimum dosage of n-HAP for FQs removal was 20 g·L-1, in which the removal efficiencies is 51.6% and 47.3%, and an adsorption equilibrium time is 20 min. The maximum removal efficiency occurred when pH is 6 for both FQs. The adsorption isotherm of FQs fits well for both Langmuir and Freundlich equations. The adsorption of both FQs by n-HAP follows second-order kinetics. PMID:26698573

  5. CO adsorption on small Aun (n = 1-4) structures supported on hematite. I. Adsorption on iron terminated α-Fe2O3 (0001) surface

    NASA Astrophysics Data System (ADS)

    Pabisiak, Tomasz; Winiarski, Maciej J.; Kiejna, Adam

    2016-01-01

    This is the first of two papers dealing with the adsorption of Au and formation of Aun nanostructures (n = 1-4) on hematite (0001) surface and adsorption of CO thereon. The stoichiometric Fe-terminated (0001) surface of hematite was investigated using density functional theory in the generalized gradient approximation of Perdew-Burke-Ernzerhof (PBE) form with Hubbard correction U, accounting for strong electron correlations (PBE+U). The structural, energetic, and electronic properties of the systems studied were examined for vertical and flattened configurations of Aun nanostructures adsorbed on the hematite surfaces. The flattened ones, which can be viewed as bilayer-like structures, were found energetically more favored than vertical ones. For both classes of structures the adsorption binding energy increases with the number of Au atoms in a structure. The adsorption of Aun induces charge rearrangement at the Aun/oxide contact which is reflected in work function changes. In most considered cases Aun adsorption increases the work function. A detailed analysis of the bonding electron charge is presented and the corresponding electron charge rearrangements at the contacts were quantified by a Bader charge analyses. The interaction of a CO molecule with the Aun nanostructures supported on α-Fe2O3 (0001) and the oxide support was studied. It is found that the CO adsorption binding to the hematite supported Aun structures is more than twice as strong as to the bare hematite surface. Analysis of the Bader charges on the atoms showed that in each case CO binds to the most positively charged (cationic) atom of the Aun structure. Changes in the electronic structure of the Aun species and of the oxide support, and their consequences for the interactions with CO, are discussed.

  6. Adsorption of atrazine on soils: model study.

    PubMed

    Kovaios, Ilias D; Paraskeva, Christakis A; Koutsoukos, Petros G; Payatakes, Alkiviades Ch

    2006-07-01

    The adsorption of the widely used herbicide atrazine onto three model inorganic soil components (silica gel, gamma-alumina, and calcite (CaCO(3)) was investigated in a series of batch experiments in which the aqueous phase equilibrated with the solid, under different solution conditions. Atrazine did not show discernible adsorption on gamma-alumina (theta=25 degrees C, 3.8adsorption from solutions was found for silica gel suspensions. The adsorption isotherms obtained for atrazine uptake on silica gel particles were best fitted with the Freundlich model. An increase of the ionic strength of the electrolytic solution induced an increase of the surface concentration of atrazine on silica gel, indicating significant electrostatic interactions between atrazine and silica gel particles, possibly through interaction with the surface silanol groups of the solid substrate. Increase of the pH value of the electrolyte solution from 6 to 9 considerably decreased the amount of atrazine adsorbed on the silica gel substrate. Decrease of the solution pH from 6 to 3 had only a slight effect on the surface concentration of the adsorbed atrazine. The adsorption of atrazine on silica gel increased when the temperature was decreased from 40 to 25 degrees C, an indication that the adsorption is exothermic. The calculated enthalpy of adsorption ( approximately 10 kJ/mol) indicates that the uptake at the solid-liquid equilibrium pH (6.1) was largely due to physisorption. PMID:16556447

  7. Improvements in glucose tolerance and insulin action induced by increasing energy expenditure or decreasing energy intake: a randomized controlled trial.

    PubMed Central

    Weiss, Edward P.; Racette, Susan B.; Villareal, Dennis T.; Fontana, Luigi; Steger-May, Karen; Schechtman, Kenneth B.; Klein, Samuel; Holloszy, John O.

    2006-01-01

    Background Weight loss, through caloric restriction (CR) or increases in exercise energy expenditure (EX), improves glucose tolerance and insulin action. However, EX may further improve glucoregulation through weight-loss independent mechanisms. Objective To assess the hypothesis that weight loss through EX improves glucoregulation and circulating factors involved in insulin action, to a greater extent than does similar weight loss through CR. Design Sedentary 50- to 60-year-old men and women (body mass index=23.5–29.9 kg/m2) were randomized to 12-month EX (n=18) or CR (n=18) weight loss interventions or to a healthy lifestyle (HL) control group (n=10). Insulin sensitivity index (ISI) and the glucose and insulin areas under the curve (AUCs) were assessed by oral glucose tolerance test (OGTT). Adiponectin and tumor necrosis factor-α (TNFα) were assessed in fasting serum. Fat mass was determined by DXA. Results Yearlong energy deficits were not different between EX and CR as evidenced by body weight and fat mass changes. ISI increased, and the glucose and insulin AUCs decreased in the EX and CR groups and remained unchanged in the HL group but did not differ between EX and CR. Marginally significant increases in adiponectin, and decreases in the TNFα-to-adiponectin ratio, occurred in the EX and CR groups but not in the HL group. Conclusions EX- and CR-induced weight losses are both effective for improving glucose tolerance and insulin action in non-obese, healthy, middle-aged men and women; however, it does not appear that exercise training-induced weight loss results in greater improvements than those that result from CR. PMID:17093155

  8. Influence of soil solution salinity on boron adsorption by soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Boron adsorption on two arid-zone soils from the San Joaquin Valley of California was investigated as a function of equilibrium solution B concentration (0-250 mg L-1), solution pH (3-12), and electrical conductivity (EC = 0.3 or 7.8 dS m-1). Boron adsorption on both soils increased with increasing...

  9. Mapping the Surface Adsorption Forces of Nanomaterials in Biological Systems

    PubMed Central

    Xia, Xin R.; Monteiro-Riviere, Nancy A.; Mathur, Sanjay; Song, Xuefeng; Xiao, Lisong; Oldenberg, Steven J.; Fadeel, Bengt; Riviere, Jim E.

    2011-01-01

    The biological surface adsorption index (BSAI) is a novel approach to characterize surface adsorption energy of nanomaterials that is the primary force behind nanoparticle aggregation, protein corona formation, and other complex interactions of nanomaterials within biological systems. Five quantitative nanodescriptors were obtained to represent the surface adsorption forces (hydrophobicity, hydrogen bond, polarity/polarizability, and lone-pair electrons) of the nanomaterial interaction with biological components. We have mapped the surface adsorption forces over 16 different nanomaterials. When the five-dimensional information of the nanodescriptors was reduced to two dimensions, the 16 nanomaterials were classified into distinct clusters according their surface adsorption properties. BSAI nanodescriptors are intrinsic properties of nanomaterials useful for quantitative structure–activity relationship (QSAR) model development. This is the first success in quantitative characterization of the surface adsorption forces of nanomaterials in biological conditions, which could open a quantitative avenue in predictive nanomedicine development, risk assessment, and safety evaluation of nanomaterials. PMID:21999618

  10. High-energy ball milling of saquinavir increases permeability across the buccal mucosa.

    PubMed

    Rambharose, Sanjeev; Ojewole, Elizabeth; Branham, Michael; Kalhapure, Rahul; Govender, Thirumala

    2014-05-01

    Saquinavir (SQV), a candidate for buccal drug delivery, is limited by poor solubility. This study identified the effects of high-energy ball milling on the buccal permeability of SQV and compared it to the effects of chemical enhancers, i.e. ethylenediaminetetraacetic acid (EDTA), sodium lauryl sulfate (SLS), polyethylene glycol (PEG) and beta cyclodextrin (β-cyclodextrin). SQV was ball milled using a high energy planetary mill (1, 3, 15 and 30 h) and permeation studies across porcine buccal mucosa were performed using franz diffusion cells. Drug was quantified by UV spectrophotometry. Both unmilled and milled SQV samples were able to permeate the buccal mucosa. Milled samples of 15 h displayed the greatest flux of 10.40 ± 1.24 µg/cm(2 )h and an enhancement ratio of 2.61. All enhancers were able to increase the buccal permeability of unmilled SQV, with SLS achieving the greatest flux (6.99 ± 0.7 µg/cm(2)) and an enhancement ratio of 1.75. However, all the milled SQV samples displayed greater permeability than SLS, the best chemical enhancer for unmilled SQV. Enhanced permeability by ball milling was attributed to reduction in particle size, formation of solid dispersions and an increase in solubility of milled samples. Microscopical evaluation revealed no significant loss in mucosal cellular integrity treated with either unmilled or milled SQV. Histological studies suggest that SQV uses both the paracellular and transcellular route of transport across the mucosa, with drug treatment having no permanent affects. High-energy ball milling was superior to the chemical enhancers studied for enhancement of SQV buccal permeation. PMID:24499179

  11. Optimum conditions for adsorptive storage.

    PubMed

    Bhatia, Suresh K; Myers, Alan L

    2006-02-14

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

  12. Influence of Ca2+ on tetracycline adsorption on montmorillonite.

    PubMed

    Parolo, M Eugenia; Avena, Marcelo J; Pettinari, Gisela R; Baschini, Miria T

    2012-02-15

    The adsorption of tetracycline (TC) on montmorillonite was studied as a function of pH and Ca(2+) concentration using a batch technique complemented with X-ray diffraction and transmission electron microscopy. In the absence of Ca(2+), TC adsorption was high at low pH and decreased as the pH increased. In the presence of Ca(2+), at least two different adsorption processes took place in the studied systems, i.e., cation exchange and Ca-bridging. Cation exchange was the prevailing process at pH<5, and thus, TC adsorption decreased by increasing total Ca(2+) concentration. On the contrary, Ca-bridging was the prevailing process at pH>5, and thus, TC adsorption increased by increasing Ca(2+) concentration. The pH 5 represents an isoadsorption pH where both adsorption processes compensate each other. TC adsorption became independent of Ca(2+) concentration at this pH. For TC adsorption on Ca(2+)-montmorillonite in 0.01 M NaCl experiments, the ratio adsorbed TC/retained Ca(2+) was close to 1 in the pH range of 5-9, indicating an important participation of Ca(2+) in the binding of TC to montmorillonite. X-ray diffraction and transmission electron microscopy showed that TC adsorption induced intercalation between montmorillonite layers forming a multiphase system with stacking of layers with and without intercalated TC. PMID:22189389

  13. Ingestion of a moderately high caffeine dose before exercise increases postexercise energy expenditure.

    PubMed

    Fernández-Elías, Valentín E; Del Coso, Juan; Hamouti, Nassim; Ortega, Juan F; Muñoz, Gloria; Muñoz-Guerra, Jesus; Mora-Rodríguez, Ricardo

    2015-02-01

    Caffeine is an ergogenic aid widely used before and during prolonged exercise. Due to its prolonged biological half-life caffeine effects could remain after exercise. We aimed to investigate the metabolic, respiratory, and cardiovascular postexercise responses to preexercise graded caffeine ingestion. Twelve aerobically trained subjects (mean VO₂max = 54 ± 7 ml · min⁻¹ · kg⁻¹) cycled for 60-min at 75% VO₂max after ingesting placebo (0 mg of caffeine per kg of body weight) or 0.5, 1.5, 3.0 and 4.5 mg · kg⁻¹ on five occasions. During the 3 hr postexercise, heart rate, blood pressure, glucose, lactate, and fatty acids were analyzed. None of these variables were statistically affected by preexercise caffeine ingestion between 0.5 and 4.5 mg · kg⁻¹. However, ingestion of 4.5 mg · kg⁻¹ of caffeine raised postexercise energy expenditure 15% above placebo (233 ± 58 vs. 202 ± 49 kcal/3 hr; p < .05). Ventilation and tidal volume were elevated after the 4.5 mg · kg⁻¹ caffeine dose above placebo (9.2 ± 2.5 L · min⁻¹ and 0.67 ± 0.29 L · breath⁻¹ vs. 7.8 ± 1.5 L · min⁻¹ and 0.56 ± 0.20 L · breath⁻¹, respectively; p < .05). Ventilation correlated with tidal volume (r = .45; p < .05) and energy expenditure (r = .72; p < .05). In summary, preexercise ingestion of ergogenic caffeine doses do not alter postexercise cardiovascular responses. However, ingestion of 4.5 mg · kg⁻¹ of caffeine raises 3-hr postexercise energy expenditure (i.e., 31 kcal) likely through increased energy cost of ventilation. PMID:24901809

  14. The Role of Lactic Acid Adsorption by Ion Exchange Chromatography

    PubMed Central

    Zhang, Tongcun; Zhang, Jian; Jia, Shiru; Yu, Changyan; Jiang, Kunyu; Gao, Nianfa

    2010-01-01

    Background The polyacrylic resin Amberlite IRA-67 is a promising adsorbent for lactic acid extraction from aqueous solution, but little systematic research has been devoted to the separation efficiency of lactic acid under different operating conditions. Methodology/Principal Findings In this paper, we investigated the effects of temperature, resin dose and lactic acid loading concentration on the adsorption of lactic acid by Amberlite IRA-67 in batch kinetic experiments. The obtained kinetic data followed the pseudo-second order model well and both the equilibrium and ultimate adsorption slightly decreased with the increase of the temperature at 293–323K and 42.5 g/liter lactic acid loading concentration. The adsorption was a chemically heterogeneous process with a mean free energy value of 12.18 kJ/mol. According to the Boyd_plot, the lactic acid uptake process was primarily found to be an intraparticle diffusion at a lower concentration (<50 g/liter) but a film diffusion at a higher concentration (>70 g/liter). The values of effective diffusion coefficient Di increased with temperature. By using our Equation (21), the negative values of ΔG° and ΔH° revealed that the adsorption process was spontaneous and exothermic. Moreover, the negative value of ΔS° reflected the decrease of solid-liquid interface randomness at the solid-liquid interface when adsorbing lactic acid on IRA-67. Conclusions/Significance With the weakly basic resin IRA-67, in situ product removal of lactic acid can be accomplished especially from an open and thermophilic fermentation system without sterilization. PMID:21085600

  15. Adsorption of chlorophenols on granular activated carbon

    SciTech Connect

    Yang, M.

    1993-12-31

    Studies were undertaken of the adsorption of chlorinated phenols from aqueous solution on granular activated carbon (Filtrasorb-400, 30 x 40 mesh). Single-component equilibrium adsorption data on the eight compounds in two concentration ranges at pH 7.0 fit the Langmuir equation better than the Freundlich equation. The adsorptive capacities at pH 7.0 increase from pentachlorophenol to trichlorophenols and are fairly constant from trichlorophenols to monochlorophenols. The adsorption process was found to be exothermic for pentachlorophenol and 2,4,6-trichlorophenol, and endothermic for 2,4-dichlorophenol and 4-chlorophenol. Equilibrium measurements were also conducted for 2,4,5-trichlorophenol, 2,4-dichlorophenol, and 4-chlorophenol over a wide pH range. A surface complexation model was proposed to describe the effect of pH on adsorption equilibria of chlorophenols on activated carbon. The simulations of the model are in excellent agreement with the experimental data. Batch kinetics studies were conducted of the adsorption of chlorinated phenols on granular activated carbon. The results show that the surface reaction model best describes both the short-term and long-term kinetics, while the external film diffusion model describes the short-term kinetics data very well and the linear-driving-force approximation improved its performance for the long-term kinetics. Multicomponent adsorption equilibria of chlorophenols on granular activated carbon was investigated in the micromolar equilibrium concentration range. The Langmuir competitive and Ideal Adsorbed Solution (IAS) models were tested for their performance on the three binary systems of pentachlorophenol/2,4,6-trichlorophenol, 2,4,6-trichlorophenol/2,4-dichlorophenol, and 2,4-dichlorophenol/4-chlorophenol, and the tertiary system of 2,4,6-trichlorophenol/2,4-dichlorophenol/4-chlorophenol, and found to fail to predict the two-component adsorption equilibria of the former two binary systems and the tertiary system.

  16. Uranium Isotopic Fractionation Induced by U(VI) Adsorption Onto Common Aquifer Minerals

    NASA Astrophysics Data System (ADS)

    Jemison, N.; Johnson, T. M.; Shiel, A. E.; Lundstrom, C.

    2014-12-01

    Mining and processing of uranium (U) ore for nuclear energy and weapons has led to U contamination of groundwater. Reduction of soluble, mobile U(VI) to UO2 decreases uranium groundwater concentrations and is an important driver of natural and stimulated attenuation. 238U/235U measurements can be used to monitor and perhaps quantify U(VI) reduction; biological reduction of U(VI) has been shown to produce a ~1.0‰ isotopic fractionation in both laboratory and field settings, with the reduced product enriched in 238U. However, adsorption of U(VI) onto minerals may complicate the use of 238U/235U in this application; adsorption of U(VI) onto Mn oxides induces an isotopic fractionation of 0.2‰ with the sorbed U(VI) depleted in 238U. At present, the isotopic shift produced by adsorption of U(VI) onto other minerals has not yet been explored. This study measures U isotopic fractionation during adsorption onto goethite, birnessite, quartz, illite, and complex aquifer materials. In addition, the effect of U speciation on fractionation is also examined by adsorption of uranyl (UO22+), uranyl carbonato (such as UO2(CO3)22- and UO2(CO3)34-), and calcium uranyl carbonato (Ca2UO2(CO3)3(aq) and CaUO2(CO3)32-) ions to goethite and birnessite. Experiments are carried out with a multi-stage, batch approach, in which a U(VI)-bearing solution is exposed to three stages of adsorption, and the final solution is analyzed by a double-spike MC-ICP-MS method. This increases our ability to resolve among sorbents the extent of fractionation. Early results suggest that uranium adsorption to different minerals produces different isotopic fractionations, with quartz producing little to no fractionation (<0 .05‰), while goethite produces a 0.16‰ isotopic shift (adsorbed U(VI) depleted in 238U).

  17. Glucagon increases energy expenditure independently of brown adipose tissue activation in humans

    PubMed Central

    Salem, V; Izzi-Engbeaya, C; Coello, C; Thomas, D B; Chambers, E S; Comninos, A N; Buckley, A; Win, Z; Al-Nahhas, A; Rabiner, E A; Gunn, R N; Budge, H; Symonds, M E; Bloom, S R; Tan, T M; Dhillo, W S

    2016-01-01

    Aims To investigate, for a given energy expenditure (EE) rise, the differential effects of glucagon infusion and cold exposure on brown adipose tissue (BAT) activation in humans. Methods Indirect calorimetry and supraclavicular thermography was performed in 11 healthy male volunteers before and after: cold exposure; glucagon infusion (at 23 °C); and vehicle infusion (at 23 °C). All volunteers underwent 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/CT scanning with cold exposure. Subjects with cold-induced BAT activation on 18F-FDG PET/CT (n = 8) underwent a randomly allocated second 18F-FDG PET/CT scan (at 23 °C), either with glucagon infusion (n = 4) or vehicle infusion (n = 4). Results We observed that EE increased by 14% after cold exposure and by 15% after glucagon infusion (50 ng/kg/min; p < 0.05 vs control for both). Cold exposure produced an increase in neck temperature (+0.44 °C; p < 0.001 vs control), but glucagon infusion did not alter neck temperature. In subjects with a cold-induced increase in the metabolic activity of supraclavicular BAT on 18F-FDG PET/CT, a significant rise in the metabolic activity of BAT after glucagon infusion was not detected. Cold exposure increased sympathetic activation, as measured by circulating norepinephrine levels, but glucagon infusion did not. Conclusions Glucagon increases EE by a similar magnitude compared with cold activation, but independently of BAT thermogenesis. This finding is of importance for the development of safe treatments for obesity through upregulation of EE. PMID:26434748

  18. Black ginger extract increases physical fitness performance and muscular endurance by improving inflammation and energy metabolism.

    PubMed

    Toda, Kazuya; Hitoe, Shoketsu; Takeda, Shogo; Shimoda, Hiroshi

    2016-05-01

    We previously reported that polymethoxyflavones (PMFs) in black ginger (Kaempferia parviflora) extract (KPE) increased energy production by activating AMP-activated protein kinase (AMPK) in C2C12 myoblasts. We herein evaluated the effects of KPE on physical fitness performance and muscular endurance in mice. Male mice were orally administered KPE for 4 weeks, and then forced swimming test, open-field test, inclined plane test, and wire hanging test were performed. KPE significantly increased the swimming time, motility after swimming, and grip strength. IL-6 and TNF-α mRNA expression levels were decreased in the soleus muscle, whereas peroxisome proliferator-activated receptor γ coactivator (PGC)-1α and glycogen synthase mRNA expression levels, mitochondrial number, and glycogen content were increased. These results were in agreement with those obtained for KPE and PMFs in C2C12. Therefore, the activation of AMPK by PMFs may be one of the mechanisms by which KPE improves physical fitness performance and muscular endurance. PMID:27441286

  19. Microcystin-LR Adsorption by Activated Carbon.

    PubMed

    Pendleton, Phillip; Schumann, Russell; Wong, Shiaw Hui

    2001-08-01

    We use a selection of wood-based and coconut-based activated carbons to investigate the factors controlling the removal of the hepatotoxin microcystin-LR (m-LR) from aqueous solutions. The wood carbons contain both micropores and mesopores. The coconut carbons contain micropores only. Confirming previously published observations, we also find that the wood-based carbons adsorb more microcystin than the coconut-based carbons. From a combination of a judicious modification of a wood-based carbon's surface chemistry and of the solution chemistry, we demonstrate that both surface and solution chemistry play minor roles in the adsorption process, with the adsorbent surface chemistry exhibiting less influence than the solution chemistry. Conformational changes at low solution pH probably contribute to the observed increase in adsorption by both classes of adsorbent. At the solution pH of 2.5, the coconut-based carbons exhibit a 400% increased affinity for m-LR compared with 100% increases for the wood-based carbons. In an analysis of the thermodynamics of adsorption, using multiple temperature adsorption chromatography methods, we indicate that m-LR adsorption is an entropy-driven process for each of the carbons, except the most hydrophilic and mesoporous carbon, B1. In this case, exothermic enthalpy contributions to adsorption also exist. From our overall observations, since m-LR contains molecular dimensions in the secondary micropore width range, we demonstrate that it is important to consider both the secondary micropore and the mesopore volumes for the adsorption of m-LR from aqueous solutions. Copyright 2001 Academic Press. PMID:11446779

  20. Novel sandwich structure adsorptive membranes for removal of 4-nitrotoluene from water.

    PubMed

    Guo, Yuexin; Jia, Zhiqian

    2016-11-01

    Novel sandwich PES-SPES/PS-PDVB/PTFE adsorptive membranes were prepared by a filtration/immersion precipitation method and employed for the removal of 4-nitrotoluene from water. The static adsorption thermodynamics, kinetics, dynamic adsorption/desorption and membrane reusability were investigated. The results showed that the Freundlich model describes the adsorption isotherm satisfactorily. With increased PS-PDVB content, the maximum static adsorption capacity, partition coefficient, apparent adsorption rate constant, and dynamic adsorption capacity all significantly increased. The sandwich membranes showed much higher removal efficiency and adsorption capacity than those of mixed matrix membranes. With respect to dynamics adsorption/desorption, the sandwich membranes exhibited excellent reusability, with a removal efficiency greater than 95% even after five recycles. PMID:27322899

  1. Impact of carbon nanotube morphology on phenanthrene adsorption.

    PubMed

    Apul, Onur Guven; Shao, Ting; Zhang, Shujuan; Karanfil, Tanju

    2012-01-01

    The present study examined the roles of the specific surface area (SSA), diameter, and length of carbon nanotubes (CNT) on the adsorption of phenanthrene (PNT) by analyzing the adsorption isotherms obtained with several single-walled carbon nanotubes (SWNT) and multiwalled carbon nanotubes (MWNT). At low equilibrium concentrations (e.g., 1 ppb), MWNTs with larger outer diameters exhibited higher PNT adsorption capacity on an SSA basis than those with smaller diameters. With increasing equilibrium concentration, adsorption on an SSA basis became independent of MWNT diameter, and the total surface area controlled maximum adsorption capacity. A similar analysis for the adsorption of naphthalene, a planar molecule with one less benzene ring but 20 times higher solubility than PNT, showed no correlation with respect to MWNT outer diameter. The results indicated that the surface curvature of MWNT was more important on the adsorption of PNT than on the adsorption of naphthalene. Specific surface area normalized isotherms did not show a correlation between PNT adsorption and lengths of SWNTs and MWNTs. Characterization results indicated that the morphology of CNTs plays an important role on the SSA and pore volume. Data from the manufacturer may not always represent the characteristics of CNTs in a particular batch. Therefore, accurate characterization of CNTs is critical to systematically examine the behavior of CNTs, such as adsorption and transport, in environmental systems. PMID:22002628

  2. Preparation and adsorption performance of MnO2/PAC composite towards aqueous glyphosate.

    PubMed

    Cui, Hao; Li, Qin; Qian, Yan; Zhang, Qiu; Zhai, Jianping

    2012-09-01

    Glyphosate (N-phosphonomethylglycine (PMG)) is the organophosphate herbicide most widely used in the world, and industrial production of PMG generates large quantities of wastewater. A manganese dioxide-coated powdered activated carbon (MnO2/PAC) composite was synthesized and investigated for the adsorption of PMG from wastewater. The results of scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectrometry (EDAX) revealed that MnO2 was formed on the surface of the carbon during the modification process. Batch adsorption results showed that the optimal pH for glyphosate adsorption on MnO2/PAC was 3.0. In the range 0.01(-1) molL(-1), glyphosate removal by MnO2/PAC decreased with an increase in ionic strength. Among the coexistent anions, only phosphate showed significant inhibition of PMG removal due to competitive complexation. Batch studies revealed that MnO2/PAC could reach a maximum PMG adsorption capacity of 283 mg g(-1). The Langmuir equilibrium model was found to be suitable for describing PMG sorption, and kinetic studies revealed that adsorption followed second-order rate kinetics. It was also proved that the adsorbed PMG could be effectively desorbed from MnO2/PAC in 1.0 molL(-1) NaOH. All of these results implied that the MnO2/PAC composite may be used as an effective adsorbent for recycling PMG from wastewater. PMID:23240199

  3. Adsorption of HMF from water/DMSO solutions onto hydrophobic zeolites: experiment and simulation.

    PubMed

    Xiong, Ruichang; León, Marta; Nikolakis, Vladimiros; Sandler, Stanley I; Vlachos, Dionisios G

    2014-01-01

    The adsorption of 5-hydroxymethylfurfural (HMF), DMSO, and water from binary and ternary mixtures in hydrophobic silicalite-1 and dealuminated Y (DAY) zeolites at ambient conditions was studied by experiments and molecular modeling. HMF and DMSO adsorption isotherms were measured and compared to those calculated using a combination of grand canonical Monte Carlo and expanded ensemble (GCMC-EE) simulations. A method based on GCMC-EE simulations for dilute solutions combined with the Redlich-Kister (RK) expansion (GCMC-EE-RK) is introduced to calculate the isotherms over a wide range of concentrations. The simulations, using literature force fields, are in reasonable agreement with experimental data. In HMF/water binary mixtures, large-pore hydrophobic zeolites are much more effective for HMF adsorption but less selective because large pores allow water adsorption because of H2 O-HMF attraction. In ternary HMF/DMSO/water mixtures, HMF loading decreases with increasing DMSO fraction, rendering the separation of HMF from water/DMSO mixtures by adsorption difficult. The ratio of the energetic interaction in the zeolite to the solvation free energy is a key factor in controlling separation from liquid mixtures. Overall, our findings could have an impact on the separation and catalytic conversion of HMF and the rational design of nanoporous adsorbents for liquid-phase separations in biomass processing. PMID:24106213

  4. Effective interactions in multisite cells for adsorption in microporous materials

    NASA Astrophysics Data System (ADS)

    Demontis, Pierfranco; Pazzona, Federico G.; Suffritti, Giuseppe B.

    2009-04-01

    Local, discrete models of self-interacting multisite adsorption cells have been shown to be able to provide a coarse-grained representation of equilibrium properties of small molecules adsorbed in nanoporous materials at the mesoscopic scale. In the present work we show how the essential statistical properties of a host cell of structured sites with multiple adsorption energies and particle-particle interactions (that is the partition function, the average energy, and the average number of guests close to the windows connecting the cell to its surroundings) can be reproduced by a less-structured cell with two occupancy-dependent adsorption energy levels.

  5. Adsorption characteristics of Thiophene on Cu and Ni(100): role of van der Waals

    NASA Astrophysics Data System (ADS)

    Rojas, Tomas; Matos, Jeronimo; Kara, Abdelkader

    2014-03-01

    We apply density functional theory, with and without the inclusion of self-consistent van der Waals (vdWs) interactions (optB86, optB88, optPBE, revPBE, rPW86), to study the adsorption of thiophene (C4H4S) on Cu(100) and Ni(100). Our calculations reveal that the C4H4S molecule adsorbs, on either substrate, with its molecular plane parallel to the surface with the sulfur close to the bridge site. The inclusion of vdWs interactions results in a significant increase in the binding energy of thiophene on Cu(100) (from 0.12 eV to up to 0.77 eV), while the adsorption height is also modified from 3.2 A down to, at most, 2.38 A, depending on the functional used. The Ni(100) case presents a similar behavior for the binding energy (enhancement from 1.56 eV to up to 2.34 eV), but the adsorption heights increase from 2.12 Å up to 2.32 Å. In addition to adsorption geometry and energetics, we present the results and analysis of the electronic properties (charge transfer, changes in the d-band of the substrate, and change in the work function) of these two systems to complement our understanding of the molecule-substrate bonding. Our results suggest that the adsorption characteristics are dependent on the type of functional used; opt-type functionals (optB86, optB88, optPBE) are found to produce stronger bonding as compared to PBE, revPBE and rPW86. This work is funded by the U.S. Department of Energy Basic Energy Science under Contract No DE-FG02-11ER16243.

  6. A Novel Dual-Rotor Turbine for Increased Wind Energy Capture

    NASA Astrophysics Data System (ADS)

    Rosenberg, A.; Selvaraj, S.; Sharma, A.

    2014-06-01

    Horizontal axis wind turbines suffer from aerodynamic inefficiencies in the blade root region (near the hub) due to several non-aerodynamic constraints. Aerodynamic interactions between turbines in a wind farm also lead to significant loss of wind farm efficiency. A new dual-rotor wind turbine (DRWT) concept is proposed that aims at mitigating these two losses. A DRWT is designed that uses an existing turbine rotor for the main rotor, while the secondary rotor is designed using a high lift-to-drag ratio airfoil. Reynolds Averaged Navier- Stokes computational fluid dynamics simulations are used to optimize the design. Large eddy simulations confirm the increase energy capture potential of the DRWT. Wake comparisons however do not show enhanced entrainment of axial momentum.

  7. Increasing self-regulatory energy using an Internet-based training application delivered by smartphone technology.

    PubMed

    Cranwell, Jo; Benford, Steve; Houghton, Robert J; Golembewski, Michael; Golembewksi, Michael; Fischer, Joel E; Hagger, Martin S

    2014-03-01

    Self-control resources can be defined in terms of "energy." Repeated attempts to override desires and impulses can result in a state of reduced self-control energy termed "ego depletion" leading to a reduced capacity to regulate future self-control behaviors effectively. Regular practice or "training" on self-control tasks may improve an individual's capacity to overcome ego depletion effectively. The current research tested the effectiveness of training using a novel Internet-based smartphone application to improve self-control and reduce ego depletion. In two experiments, participants were randomly assigned to either an experimental group, which received a daily program of self-control training using a modified Stroop-task Internet-based application delivered via smartphone to participants over a 4-week period, or a no-training control group. Participants assigned to the experimental group performed significantly better on post-training laboratory self-control tasks relative to participants in the control group. Findings support the hypothesized training effect on self-control and highlight the effectiveness of a novel Internet-based application delivered by smartphone as a practical means to administer and monitor a self-control training program. The smartphone training application has considerable advantages over other means to train self-control adopted in previous studies in that it has increased ecological validity and enables effective monitoring of compliance with the training program. PMID:24015984

  8. On the possibility of increasing the pulse energy of a passively Q-switched erbium glass minilaser

    SciTech Connect

    Izyneev, A A; Sadovskii, Pavel I; Sadovskii, S P

    2010-08-03

    A simple method to increase the output energy of a passively Q-switched erbium glass laser is proposed. Using the amplitude modulation of losses at the active element face, the fundamental mode was reliably suppressed and the laser operated in a selected higher-order mode. The output energy was experimentally increased by a factor of 2.1, and the range of allowable pump energy instability was extended threefold. (lasers)

  9. Ammonia Production Using Pressure Swing Adsorption

    SciTech Connect

    2009-02-01

    This factsheet describes a research project whose overall objective is to develop and demonstrate a technically feasible and commercially viable system that integrates reaction to produce ammonia along with recovery of the products by adsorption separation methods and significantly decrease the energy requirement in ammonia production.

  10. Study of Gas Adsorption on Biphasic Nanostructured Surfaces

    NASA Astrophysics Data System (ADS)

    Nader, Rami; Hamieh, Tayssir; Villieras, Frédéric; Angelina. Razafitianamaharav; Toufaily, Joumana; Mcheik, Ali S.; Thomas, Fabien

    This work has carried out on grafted nanoparticles oxide silica to determine the possible existence of "nanoeffect". The textural properties and heterogeneity of surface of the samples were studied at the interface solid-gas. The Geometric properties were discussed in terms of the surface area while the energy properties were discussed in terms of the reactive sites of the surface.In the framework of this study, firstly, the sample was used in the non-grafted state and then in the grafted state using a hydrophilic molecule and a hydrophobic molecule. Several techniques have been used: Infrared spectroscopy, X ray diffraction, the point by point volumetric technique, which enable us to study the interactions between the adsorbate and the solid surface. Finally we have determined the size and electro thermal mobility using zestasizer (Nano ZS). The results obtained show that there are two types of groups silanols and siloxanes on the silica OX5 giving a composite hydrophilic-hydrophobic. This character causes a singular behavior in adsorptive material, the presence of hydrophilic groups, strongly polarized, and is detected by infrared spectroscopy. These groups cause significant differences depending on the polarizability of the probe molecules, and the adsorption of argon shows no heterogeneity of the surface, while nitrogen is adsorbed on the polar sites at low relative pressure, While the volumetric continues to adsorption of argon and nitrogen on combustion silica to obtain and to highlight sites of high energy and polar surface sites. The combustion silica which has been used as adsorbent in this study has an amorphous surface, virtually free of impurities indicates that the sample is not micro porous and grafting of the molecules makes a decrease in high energy sites or to a relative increase in surface low energy.

  11. A theoretical study of water adsorption and decomposition on low-index spinel ZnGa2O4 surfaces: correlation between surface structure and photocatalytic properties.

    PubMed

    Jia, Chuanyi; Fan, Weiliu; Yang, Fei; Zhao, Xian; Sun, Honggang; Li, Pan; Liu, Li

    2013-06-11

    Water adsorption and decomposition on stoichiometrically perfect and oxygen vacancy containing ZnGa2O4 (100), (110), and (111) surfaces were investigated through periodic density functional theory (DFT) calculations. The results demonstrated that water adsorption and decomposition are surface-structure-sensitive processes. On a stoichiometrically perfect surface, the most stable molecular adsorption that could take place involved the generation of hydrogen bonds. For dissociative adsorption, the adsorption energy of the (111) surface was more than 4 times the energies of the other two surfaces, indicating it to be the best surface for water decomposition. A detailed comparison of these three surfaces showed that the primary reason for this observation was the special electronic state of the (111) surface. When water dissociated on the (111) surface, the special Ga3c-4s and 4p hybridization states at the Fermi level had an obvious downshift to the lower energies. This large energy gain greatly promoted the dissociation of water. Because the generation of O(3c) vacancy defects on the (100) and (110) surfaces could increase the stability of the dissociative adsorption states with few changes to the energy barrier, this type of defect would make the decomposition of water molecules more favorable. However, for the (111) surface, the generation of vacancy defects could decrease the stability of the dissociative adsorption states and significantly increase their energy barriers. Therefore, the decomposition of water molecules on the oxygen vacancy defective (111) surface would be less favorable than the perfect (111) surface. These findings on the decomposition of H2O on the ZnGa2O4 surfaces can be used toward the synthesis of water-splitting catalysts. PMID:23682995

  12. Analysis of Adsorbate-Adsorbate and Adsorbate-Adsorbent Interactions to Decode Isosteric Heats of Gas Adsorption.

    PubMed

    Madani, S Hadi; Sedghi, Saeid; Biggs, Mark J; Pendleton, Phillip

    2015-12-21

    A qualitative interpretation is proposed to interpret isosteric heats of adsorption by considering contributions from three general classes of interaction energy: fluid-fluid heat, fluid-solid heat, and fluid-high-energy site (HES) heat. Multiple temperature adsorption isotherms are defined for nitrogen, T=(75, 77, 79) K, argon at T=(85, 87, 89) K, and for water and methanol at T=(278, 288, 298) K on a well-characterized polymer-based, activated carbon. Nitrogen and argon are subjected to isosteric heat analyses; their zero filling isosteric heats of adsorption are consistent with slit-pore, adsorption energy enhancement modelling. Water adsorbs entirely via specific interactions, offering decreasing isosteric heat at low pore filling followed by a constant heat slightly in excess of water condensation enthalpy, demonstrating the effects of micropores. Methanol offers both specific adsorption via the alcohol group and non-specific interactions via its methyl group; the isosteric heat increases at low pore filling, indicating the predominance of non-specific interactions. PMID:26538339

  13. Adsorption of isopropanol and cyclohexane on zinc oxide

    NASA Astrophysics Data System (ADS)

    Bratchikova, I. G.; Pylinina, A. I.; Platonov, E. A.; Danilova, M. N.; Isaeva, N. Yu.; Yagodovskii, V. D.

    2015-01-01

    Adsorption isotherms of isopropanol and cyclohexane are obtained in the range of 234-303 K on an initial surface of zinc oxide and after its treatment with glow-discharge plasma in O2 and high-frequency plasma in Ar. The values of isosteric heat and adsorption entropy are shown to be only slightly affected by these treatments. It is found that the acidity of the surface increases by 38 and 97%, respectively, and the acidic sites are not adsorption sites for either adsorbate. At low degrees of occupation, the adsorption isotherms of (CH3)2CHOH are described by an equation of induced adsorption whose parameters are dependent on the plasma-chemical treatments. It is concluded that adsorbed isopropanol particles exist in positively and negatively charged forms. The adsorption of cyclohexane is described by the Hill-de Boer equation for the initial ZnO surface, and by the Langmuir equation after plasma-chemical treatments.

  14. Entropic nature of the adsorption of sodium dodecylbenzenesulfonate on nanoparticles of aluminum and iron oxides in aqueous medium

    NASA Astrophysics Data System (ADS)

    Mansurov, R. R.; Safronov, A. P.; Lakiza, N. V.

    2016-06-01

    The adsorption of anionic surfactant sodium dodecylbenzenesulfonate (SDBS) from aqueous solution on the hydrophilic surfaces of aluminum oxide and iron oxide nanoparticles is studied via UV spectrophotometry, electrophoretic light scattering, and isothermal microcalorimetry. It is shown that the isotherms of the adsorption of SDBS on the surfaces of both oxides in the area of concentrations up to 0.6 mmol/L is linear. It is found that the positive zeta potential of the surfaces of the particles falls to zero and shifts toward the range of negative values due to adsorption. The adsorption of SDBS is characterized by positive enthalpy values over the investigated range of concentrations, while the loss of energy during adsorption indicates it is of an entropic nature. It is concluded that the probable cause of the increase in entropy is the dehydration of SDBS molecules during on surface adsorption. The obtained results are discussed in terms of the formation of hemimicelles of surfactant on the hydrophilic surfaces of metal oxide nanoparticles in an aqueous medium.

  15. First-principles study of oxygen and hydrogen adsorption on Pt(111) and PtML/Pd(111) surfaces

    NASA Astrophysics Data System (ADS)

    Nie, J. L.; Ao, L.; Zu, X. T.

    2015-11-01

    In this paper, first-principles calculations based on density functional theory (DFT) have been performed to investigate the adsorption of oxygen and hydrogen on Pt(111) and Pd(111) surfaces covered by monolayer (ML) of Pt(PtML/Pd(111)). The results have shown that the oxygen molecule tends to adsorb on fcc site on both surfaces at the coverage of 0.25 ML, which becomes degeneration with hcp site when the coverage increases to 1 ML. For both oxygen and hydrogen, the adsorption on PtML/Pd(111) surface are stronger than those on Pt(111) surface. The adsorption energy difference for oxygen on the two surfaces is ˜0.2 eV at the coverage of 1 ML, which increases to ˜0.6 eV with the coverage decreasing to 0.25 ML. The similar energy difference was also found for hydrogen adsorption. The density of states analysis have demonstrated the chemical interaction of adsorbed oxygen with both pure Pt(111) and PtML/Pd(111) surfaces with certain shift of O2p states to lower level compared to isolated oxygen. For hydrogen adsorption, the hybridization of H1s with Pt5d states were observed for both surfaces, indicating the covalent bonding component of H-Pt bond.

  16. Energy budget closure observed in paired Eddy Covariance towers with increased and continuous daily turbulence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The lack of energy closure has been a longstanding issue with Eddy Covariance (EC). Multiple mechanisms have been proposed to explain the discrepancies in energy balance including diurnal energy storage changes, advection of energy, and larger scale turbulent processes that cannot be resolved by fi...

  17. Competitive adsorption of a binary CO2-CH4 mixture in nanoporous carbons: effects of edge-functionalization

    NASA Astrophysics Data System (ADS)

    Lu, Xiaoqing; Jin, Dongliang; Wei, Shuxian; Zhang, Mingmin; Zhu, Qing; Shi, Xiaofan; Deng, Zhigang; Guo, Wenyue; Shen, Wenzhong

    2014-12-01

    The effect of edge-functionalization on the competitive adsorption of a binary CO2-CH4 mixture in nanoporous carbons (NPCs) has been investigated for the first time by combining density functional theory (DFT) and grand canonical Monte Carlo (GCMC) simulation. Our results show that edge-functionalization has a more positive effect on the single-component adsorption of CO2 than CH4, therefore significantly enhancing the selectivity of CO2 over CH4, in the order of NH2-NPC > COOH-NPC > OH-NPC > H-NPC > NPC at low pressure. The enhanced adsorption originates essentially from the effects of (1) the conducive environment with a large pore size and an effective accessible surface area, (2) the high electronegativity/electropositivity, (3) the strong adsorption energy, and (4) the large electrostatic contribution, due to the inductive effect/direct interaction of the embedded edge-functionalized groups. The larger difference from these effects results in the higher competitive adsorption advantage of CO2 in the binary CO2-CH4 mixture. Temperature has a negative effect on the gas adsorption, but no obvious influence on the electrostatic contribution on selectivity. With the increase of pressure, the selectivity of CO2 over CH4 first decreases sharply and subsequently flattens out to a constant value. This work highlights the potential of edge-functionalized NPCs in competitive adsorption, capture, and separation for the binary CO2-CH4 mixture, and provides an effective and superior alternative strategy in the design and screening of adsorbent materials for carbon capture and storage.The effect of edge-functionalization on the competitive adsorption of a binary CO2-CH4 mixture in nanoporous carbons (NPCs) has been investigated for the first time by combining density functional theory (DFT) and grand canonical Monte Carlo (GCMC) simulation. Our results show that edge-functionalization has a more positive effect on the single-component adsorption of CO2 than CH4, therefore

  18. Adsorption behavior of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) on boehmite.

    PubMed

    Wang, Fei; Liu, Chengshuai; Shih, Kaimin

    2012-11-01

    Understanding the interaction of perfluorochemicals, persistent pollutants with known human health effects, with mineral compounds in surface water and groundwater environments is essential to determining their fate and transport. Kinetic experiments showed that adsorption equilibrium can be achieved within 48 h and the boehmite (AlOOH) surface is receptive to perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) adsorption. The adsorption isotherms estimated the maximum adsorption capacities of PFOS and PFOA on boehmite as 0.877 μg m(-2) and 0.633 μg m(-2), respectively. Compared to the adsorption capacity on γ-alumina, the abundant hydroxyl groups on boehmite surfaces resulted in the 2-3 times higher adsorption of PFOS and PFOA. Increasing solution pH led to a moderate decrease in PFOS and PFOA adsorption, owing to an increase in ligand exchange reactions and the decrease of electrostatic interactions. The presence of NaCl and CaCl(2) in solution demonstrated negative effects for PFOS and PFOA adsorption on boehmite surfaces, with potential mechanisms being electrical double layer compression, competitive adsorption of chloride, and the Ca(2+) bridging effect between perfluorochemicals. PMID:22897837

  19. Adsorption behavior of epirubicin hydrochloride on carboxylated carbon nanotubes.

    PubMed

    Chen, Zhe; Pierre, Dramou; He, Hua; Tan, Shuhua; Pham-Huy, Chuong; Hong, Hao; Huang, Jilong

    2011-02-28

    The aim of this study was to understand the interaction between carboxylated carbon nanotubes (c-CNTs) and anticancer agents and evaluate the drug-loading ability of c-CNTs. We prepared carboxylated multi-walled carbon nanotubes (c-MWNTs) with nitric acid treatment, then evaluated the adsorption ability of c-MWNTs as adsorbents for loading of the anticancer drug, epirubicin hydrochloride (EPI), and investigated the adsorption behavior of EPI on c-MWNTs. Unmodified multi-walled carbon nanotubes (MWNTs) and single-walled carbon nanotubes (SWNTs) were included as comparative adsorbents. The results showed that carbon nanotubes were able to form supramolecular complexes with EPI via π-π stacking and possessed favorable loading properties as drug carriers. The Freundilich adsorption model was successfully employed to describe the adsorption process. Because of the high surface area and hydrogen bonding, c-MWNTs' adsorption efficiency was the highest and the most stable and their drug-loading capacity was superior to that of MWNTs. With the increase of pH, the adsorption capacity of EPI on the c-MWNTs increased. Low-temperature facilitated the adsorption. More rapid EPI adsorption rate and higher drug-loading ability were observed from c-MWNTs with smaller diameter. Moreover, the adsorption kinetics of EPI on c-MWNTs could be well depicted by using the pseudo-second-order kinetic model. PMID:21145959

  20. Adsorption of methyl green dye onto multi-walled carbon nanotubes decorated with Ni nanoferrite

    NASA Astrophysics Data System (ADS)

    Bahgat, Mohamed; Farghali, Ahmed Ali; El Rouby, Waleed; Khedr, Mohamed; Mohassab-Ahmed, Mohassab Y.

    2013-06-01

    This research was carried out to evaluate the capability of multi-walled carbon nanotubes (CNTs) and NiFe2O4-decorated multi-walled carbon nanotubes (NiFe2O4-CNTs) toward waste water treatment relevant to organic dyes. CNTs were prepared via chemical vapor deposition method. NiFe2O4-CNTs were prepared by in-situ chemical precipitation of metal hydroxides followed by hydrothermal processing. The samples were characterized using XRD and TEM. The adsorption efficiency of CNTs and NiFe2O4-CNTs of methyl green dye at various temperatures was examined. The adsorbed amount increased with the CNTs and NiFe2O4-CNTs dosage. The linear correlation coefficients and standard deviations of Langmuir and Freundlich isotherms were determined. It was found that Langmuir isotherm fitted the experimental results well in both adsorption cases n of methyl green onto CNTs and NiFe2O4-CNTs. Kinetics analyses were conducted using pseudo first-order, second-order and the intraparticle diffusion models. The results showed that the adsorption kinetics was controlled by a pseudo second-order model for adsorption of methyl green onto CNTs and best controlled by pseudo first-order in case of NiFe2O4-CNTs. Changes in the free energy of adsorption (Δ G°), enthalpy (Δ H°), entropy (Δ S°), and the activation energy ( E a) were determined. The Δ H°, Δ G° and E a values indicated that the adsorption of methyl green onto MWCNTs and NiFe2O4-MWCNTs was physisorption.

  1. Roux-en-Y Gastric Bypass Surgery Increases Respiratory Quotient and Energy Expenditure during Food Intake

    PubMed Central

    Werling, Malin; Fändriks, Lars; Olbers, Torsten; Bueter, Marco; Sjöström, Lars; Lönroth, Hans; Wallenius, Ville; Stenlöf, Kaj; le Roux, Carel W.

    2015-01-01

    Objective The mechanisms determining long-term weight maintenance after Roux-en-Y gastric bypass (RYGB) remain unclear. Cross sectional studies have suggested that enhanced energy expenditure (EE) may play a significant role and the aim of this study was to reveal the impact of RYGB on each major component constituting total EE. Design Six obese female subjects, without other co-morbidities, were assessed before and at 10 days, 3 and 20 months after RYGB. Indirect calorimetry in a metabolic chamber was used to assess 24h EE at each study visit. Other measurements included body composition by DEXA, gut hormone profiles and physical activity (PA) using high sensitivity accelerometers. Results Median Body Mass Index decreased from 41.1 (range 39.1-44.8) at baseline to 28 kg/m2 (range 22.3-30.3) after 20 months (p<0.05). Lean tissue decreased from 55.9 (range 47.5-59.3) to 49.5 (range 41.1-54.9) kg and adipose tissue from 61 (range 56-64.6) to 27 (range 12-34.3) kg (both p<0.05). PA over 24h did not change after surgery whereas 24h EE and basal metabolic rate (BMR) decreased. EE after a standard meal increased after surgery when adjusted for total tissue (p<0.05). After an initial drop, RQ (respiratory quotient) had increased at 20 months, both as measured during 24h and after food intake (p<0.05). Conclusion RYGB surgery up-regulates RQ and EE after food intake resulting in an increased contribution to total EE over 24h when corrected for total tissue. PMID:26098889

  2. Adsorption kinetics of silicic acid on akaganeite.

    PubMed

    Naren, Gaowa; Ohashi, Hironori; Okaue, Yoshihiro; Yokoyama, Takushi

    2013-06-01

    As part of a series of studies on the interaction between ferric ions and silicic acid in the hydrosphere, the adsorption of silicic acid on akaganeite was investigated kinetically at various pH values. The adsorption of silicic acid increased with increasing pH over an initial pH range of 4-11.5. In the kinetic experiment, the Cl(-) was released from akaganeite much faster than silicic acid was adsorbed. From this result, we concluded that chloride ions bound on the surface of akaganeite are released and Fe-OH or Fe-O(-) sites are formed, which then acts as an adsorption site for silicic acid. The uptake mechanism of silicic acid by akaganeite is significantly different from that by schwertmannite, despite the presence of the same tunnel structure. PMID:23538050

  3. The Adsorption of Polyelectrolytes on Hydroxyapatite Crystals.

    PubMed

    Tsortos; Nancollas

    1999-01-01

    The adsorption of two polyelectrolytes, poly-L-Glutamate and poly-L-Aspartate, on hydroxyapatite (HAP) crystals was studied both experimentally and theoretically. Langmuir adsorption isotherms were obtained for both these molecules, with binding constants K = 6 x 10(6) and 3 x 10(6) M-1, respectively, at 37.0 degreesC, pH 7.4, and 0.15 M ionic strength. A theoretical analysis of the data, based on a model proposed by Hesselink, suggested a "train-loop" type of adsorption with non-electrostatic energy terms 3.51 and 4.76 (kT) for poly-L-Glu and poly-L-Asp, respectively. Copyright 1999 Academic Press. PMID:9878142

  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. Comparative study of metal atom adsorption on free-standing h-BN and h-BN/Ni (1 1 1) surfaces

    NASA Astrophysics Data System (ADS)

    Hwang, Yubin; Chung, Yong-Chae

    2014-04-01

    In this paper, a comparative study of the adsorption behavior of single metal atoms (Li, Sc, Ti, Co, Ni, and Cu) on two systems, a free-standing hexagonal boron nitride (h-BN) sheet and an h-BN/Ni (1 1 1) surface, was performed using density functional theory calculations. It was found that the Ni (1 1 1) supporting layer under the h-BN sheet could significantly improves the adsorption energies for single metal adatoms with h-BN. In particular, in the case of Li and Sc, the improved adsorption energies were higher than the cohesive energies of their atoms. The mechanism for these strong adsorptions was primarily due to the charge transfer increases from the adsorbed metal atoms to the h-BN, except for the case of Ni. On the other hand, the adsorption behavior was greatly affected by the interface interaction between the h-BN and Ni (1 1 1) for the adsorption of a single Ni atom. These results may provide fundamental information on the interaction between the adsorbed metal atoms between the h-BN based systems, and suggest that the use of a metal-adsorbed h-BN/Ni (1 1 1) system has good potential for nanosensors and nanocatalysts.

  6. Adsorption of halide ions from aqueous solutions at a Cd(0 0 0 1) electrode surface: quantum chemical modelling and experimental study

    NASA Astrophysics Data System (ADS)

    Nazmutdinov, Renat R.; Zinkicheva, Tamara T.; Probst, Michael; Lust, Karmen; Lust, Enn

    2005-03-01

    Adsorption of the halide ions X (X = Cl -, Br -, I -) at a cadmium monocrystalline face (0 0 0 1) from aqueous solutions has been studied by the impedance spectroscopy. Analysis of the impedance data does not predict specific adsorption for Cl - and shows that the Gibbs adsorption energy increases from Br - to I - in accordance with the decrease of the hydration energy of anions. The adsorption of halide ions and their atomic forms on a Cd(0 0 0 1) electrode at the potential of zero charge (pzc) has been studied with the use of the cluster model. The quantum chemical calculations were performed at the DFT and the SCF levels involving the hydrated species X -(H 2O) 3 and X -(H 2O) 6 besides the bare anions. The effective distance-dependent solvation energy of halide ions constructed on the basis of molecular dynamics simulations was used to build the adsorption terms. For all three halides contact adsorption was found to be the most favourable state. The partial charge transfer (PCT) from the adsorbed species to the metal was analysed in terms of the Anderson-Newns model. A combined consideration of the solvation and PCT effects enables prediction of the experimentally observed metal-ion interaction order (Cl - < Br - < I -).

  7. Localized Opto-Mechanical Control of Protein Adsorption onto Carbon Nanotubes

    PubMed Central

    O'Dell, Dakota; Serey, Xavier; Kang, Pilgyu; Erickson, David

    2014-01-01

    Chemical reactions can be described by an energy diagram along a reaction coordinate in which an activation barrier limits the rate at which reactants can be transformed into products. This reaction impedance can be overcome by reducing the magnitude of the barrier through the use of catalysis, increasing the thermal energy of the system, or through macroscopic mechanical processes. Here, we demonstrate direct molecular-scale control of a reaction through the precise application of opto-mechanical work. The method uses optical gradient forces generated in the evanescent field surrounding hybrid photonic-plasmonic structures to drive an otherwise unlikely adsorption reaction between proteins and carbon nanotubes. The adsorption of immunoglobulins on carbon nanotubes is used as a model reaction and investigated with an extended DLVO theory. The technique is also used to force a Förster resonance energy transfer between fluorophores on mismatched immunoglobulin proteins and is expected to lead to novel forms of chemical synthesis. PMID:25330911

  8. Neptunium(V) adsorption to calcite.

    PubMed

    Heberling, Frank; Brendebach, Boris; Bosbach, Dirk

    2008-12-12

    The migration behavior of the actinyl ions U(VI)O2(2+), Np(V)O2+ and Pu(V,VI)O2(+,2+) in the geosphere is to a large extend controlled by sorption reactions (inner- or outer-sphere adsorption, ion-exchange, coprecipitation/structural incorporation) with minerals. Here NpO2+ adsorption onto calcite is studied in batch type experiments over a wide range of pH (6.0-9.4) and concentration (0.4 microM-40 microM) conditions. pH is adjusted by variation of CO2 partial pressure. Adsorption is found to be pH dependent with maximal adsorption at pH 8.3 decreasing with increasing and decreasing pH. pH dependence of adsorption decreases with increasing Np(V) concentration. EXAFS data of neptunyl adsorbed to calcite and neptunyl in the supernatant shows differences in the Np(V)-O-yl distance, 1.85+/-0.01 angstroms for the adsorbed and 1.82+/-0.01 angstroms for the solution species. The equatorial environment of the neptunyl in solution shows about 5 oxygen neighbours at 2.45+/-0.02 angstroms. For adsorbed neptunyl there are also about 5 oxygen neighbours at 2.46+/-0.01 angstroms. An additional feature in the adsorbed species' R-space spectrum can be related to carbonate neighbours, 3 to 6 carbon backscatterers (C-eq) at 3.05+/-0.03 angstroms and 3 to 6 oxygen backscatterers (O-eq2) at 3.31+/-0.02 angstroms. The differences in the Np(V)-O-yl distance and the C-eq and O-eq2 backscatterers which are only present for the adsorbed species indicate inner-sphere bonding of the adsorbed neptunyl species to the calcite surface. Experiments on adsorption kinetics indicate that after a fast surface adsorption process a continuous slow uptake occurs which may be explained by incorporation via surface dissolution and reprecipitation processes. This is also indicated by the part irreversibility of the adsorption as shown by increased KD values after desorption compared to adsorption. PMID:18973965

  9. Adsorption of aniline and toluidines on montmorillonite

    SciTech Connect

    Essington, M.E. )

    1994-09-01

    Bentonite clay liners are commonly employed to mitigate the movement of contaminants from waste disposal sites. In order to assess the ability of clay liner material to restrict the mobility of amine compounds under a variety of chemical conditions and to further elucidate amine adsorption characteristics, the adsorption of aniline and o-, m-, and p-toluidine on Ca[sup 2+]- and K[sup +]-saturated Wyoming bentonite (SWy-1) was investigated. Adsorption experiments were performed under conditions of varied pH and ionic environment. Amine adsorption on montmorillonite is pH dependent. Maximum amine adsorption occurs when solution pH is approximately equal to the pK[sub a] of the anilinium ion deprotonation reaction (pH 4.45-5.08). An amine adsorption envelope results from the combined influence of increasing anilinium ion and anilinium-aniline complex formation (as pH decreases to the pK[sub a]) and amine competition with H[sup +] for surface sites, decreasing anilinium-aniline complex concentration, and decreasing aniline available for water bridging with exchangeable Ca[sup 2+] and K[sup +] (as solution pH decreases below the pK[sub a]). For any given amine, maximum adsorption increases with decreasing ionic strength. Maximum amine adsorption is greater in the Ca[sup 2+] systems than in the K[sup +] systems at equivalent cation charge and reflects the formation of an amine water bridge with the exchangeable Ca[sup 2+]. Amine adsorption is also greater in chloride systems compared with sulfate systems at comparable cation concentrations, possibly due to the formation of aqueous anilinium-sulfate complexes. The amine compounds are retained mainly by bentonite through a cation exchange process, the capacity of the clay to adsorb the amine compounds being a significant percentage of the exchange capacity at the pK[sub a]. However, amine retention decreases with increasing pH and is minimal at solution pH values greater than 7. 19 refs., 6 figs.

  10. Mammary gland development of dairy heifers fed diets containing increasing levels of metabolisable protein: metabolisable energy.

    PubMed

    Albino, Ronan L; Marcondes, Marcos I; Akers, Robert M; Detmann, Edenio; Carvalho, Bruno C; Silva, Tadeu E

    2015-02-01

    This study was conducted to evaluate the development of the mammary gland in Holstein heifers subjected to different dietary metabolisable protein (MP): metabolisable energy (ME) ratios. Twenty-five Holstein heifers (initial body weight (BW) 213±13·5 kg and initial average age 7·8±0·5 months) were divided into five treatments. The treatments were designed to provide MP:ME ratios equal to 33, 38, 43, 48, and 53 g of MP per Mcal of ME. All diets were formulated to have the same energy content (2·6 Mcal ME/kg dry matter). Actual MP:ME ratios were 36·2, 40·2, 46·2, 47·1, and 50·8 g MP/Mcal ME. The experiment was conducted in a randomised block design, while considering initial BW as a blocking factor to evaluate pre- and post-pubertal periods. Block effect was not observed for all variables evaluated; hence it was considered that the diets had the same influence both on pre- and post-pubertal phases. Dry matter and nutrient intake did not change between treatments, excepting protein intake and digestibility. Serum concentrations of insulin-like growth factor 1 increased linearly across treatments. Changes in the pixel brightness of mammary gland ultrasound images, which are associated with lipid content, were significantly influenced by MP:ME ratios in the diet of heifers that were subjected to accelerated growth rates. It is not recommended to use diets of less than 38 g MP/Mcal ME in diets to heifers allowed to gain more than 1 kg/d. PMID:25592631

  11. Functionalized mesoporous silica materials for molsidomine adsorption: Thermodynamic study

    SciTech Connect

    Alyoshina, Nonna A.; Parfenyuk, Elena V.

    2013-09-15

    A series of unmodified and organically modified mesoporous silica materials was prepared. The unmodified mesoporous silica was synthesized via sol–gel synthesis in the presence of D-glucose as pore-forming agent. The functionalized by phenyl, aminopropyl and mercaptopropyl groups silica materials were prepared via grafting. The fabricated adsorbent materials were characterized by Fourier transform infrared spectroscopy (FTIR) analysis, N{sub 2} adsorption/desorption and elemental analysis methods. Then their adsorption properties for mesoionic dug molsidomine were investigated at 290–313 K and physiological pH value. Thermodynamic parameters of molsidomine adsorption on the synthesized materials have been calculated. The obtained results showed that the adsorption process of molsidomine on the phenyl modified silica is the most quantitatively and energetically favorable. The unmodified and mercaptopropyl modified silica materials exhibit significantly higher adsorption capacities and energies for molsidomine than the aminopropyl modified sample. The effects are discussed from the viewpoint of nature of specific interactions responsible for the adsorption. - Graphical abstract: Comparative analysis of the thermodynamic characteristics of molsidomine adsorption showed that the adsorption process on mesoporous silica materials is controlled by chemical nature of surface functional groups. Molsidomine adsorption on the phenyl modified silica is the most quantitatively and energetically favorable. Taking into account ambiguous nature of mesoionic compounds, it was found that molsidomine is rather aromatic than dipolar. Display Omitted - Highlights: • Unmodified and organically modified mesoporous silica materials were prepared. • Molsidomine adsorption on the silica materials was studied. • Phenyl modified silica shows the highest adsorption capacity and favorable energy. • Molsidomine exhibits the lowest affinity to aminopropyl modified silica.

  12. Effect of complexing ligands on the adsorption of Cu(II) onto the silica gel surface. 1: Adsorption of ligands

    SciTech Connect

    Park, Y.J.; Jung, K.H.; Park, K.K.; Park, K.K.

    1995-04-01

    The adsorption of several ligands on silica gel was investigated in aqueous solutions. The ligands used were 2,2{prime},6{prime},2{double_prime}-terpyridine, pyridine, 3,4-lutidine, 2-aminomethyl pyridine, 2-pyridine methanol, picolinic acid, salicylic acid, and 5-sulfosalicylic acid. The adsorption behaviors of these ligands were interpreted by means of three adsorption modes: ion exchange, hydrogen bonding, and hydrophobic interaction. For 2,2{prime},6{prime},2{double_prime}-terpyridine, pyridine, and 3,4-lutidine, the adsorption maxima appeared near their respective pK{sub a} values and were found to be due mainly to ion exchange, whereas the adsorption of these ligands at low pH was strongly attributed to hydrophobic interaction. The adsorption of 2-aminomethyl pyridine increased with increasing pH over the entire pH range investigated and was due mainly to ion exchange. Picolinic acid was adsorbed mainly by hydrogen bonding either via pyridine N atoms at low pH or via carboxylic O atoms at high pH. 2-Pyridine methanol was adsorbed by hydrophobic interaction at low pH and by hydrogen bonding at high pH. The adsorptions of salicylic and 5-sulfosalicylic acid were very small over the entire pH ranges investigated. For the adsorption mechanism, the Stern model was used to fit adsorption data.

  13. Benefits of supplementing an industrial waste anaerobic digester with energy crops for increased biogas production

    SciTech Connect

    Nges, Ivo Achu; Escobar, Federico; Fu Xinmei; Bjoernsson, Lovisa

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer This study demonstrates the feasibility of co-digestion food industrial waste with energy crops. Black-Right-Pointing-Pointer Laboratory batch co-digestion led to improved methane yield and carbon to nitrogen ratio as compared to mono-digestion of industrial waste. Black-Right-Pointing-Pointer Co-digestion was also seen as a means of degrading energy crops with nutrients addition as crops are poor in nutrients. Black-Right-Pointing-Pointer Batch co-digestion methane yields were used to predict co-digestion methane yield in full scale operation. Black-Right-Pointing-Pointer It was concluded that co-digestion led an over all economically viable process and ensured a constant supply of feedstock. - Abstract: Currently, there is increasing competition for waste as feedstock for the growing number of biogas plants. This has led to fluctuation in feedstock supply and biogas plants being operated below maximum capacity. The feasibility of supplementing a protein/lipid-rich industrial waste (pig manure, slaughterhouse waste, food processing and poultry waste) mesophilic anaerobic digester with carbohydrate-rich energy crops (hemp, maize and triticale) was therefore studied in laboratory scale batch and continuous stirred tank reactors (CSTR) with a view to scale-up to a commercial biogas process. Co-digesting industrial waste and crops led to significant improvement in methane yield per ton of feedstock and carbon-to-nitrogen ratio as compared to digestion of the industrial waste alone. Biogas production from crops in combination with industrial waste also avoids the need for micronutrients normally required in crop digestion. The batch co-digestion methane yields were used to predict co-digestion methane yield in full scale operation. This was done based on the ratio of methane yields observed for laboratory batch and CSTR experiments compared to full scale CSTR digestion of industrial waste. The economy of crop-based biogas

  14. The influence of the textural properties of activated carbons on acetaminophen adsorption at different temperatures.

    PubMed

    Galhetas, Margarida; Andrade, Marta A; Mestre, Ana S; Kangni-foli, Ekoé; Villa de Brito, Maria J; Pinto, Moisés L; Lopes, Helena; Carvalho, Ana P

    2015-05-14

    The influence of temperature (20-40 °C) on the acetaminophen adsorption onto activated carbons with different textures was studied. Different temperature dependences, not explained by kinetic effects, were observed for carbons with different micropore size distribution patterns: adsorption capacity increased for pine gasification residues (Pi-fa) derived carbons and decreased for sisal based materials. No significant variation was seen for carbon CP. The species identified by (1)H NMR spectroscopy on the back-extraction solution proved that during the adsorption process exist the conditions required to promote the formation of acetaminophen oligomers which have constrained access to the narrow microporosity. The rotation energy of the dihedral angle between monomers (estimated by electronic DFT methods) showed that conformations in the planar form are less stable than the non-planar conformation (energy barrier of 70 and 23 kJ mol(-1)), but have critical dimensions similar to the monomer and can access most of the micropore volume. The enthalpy change of the overall process showed that the energy gain of the system (endothermic) for Pi-fa samples (≈40 kJ mol(-1)) was enough to allow a change in the dimer, or even a larger oligomer, conformation to the planar form. This will permit adsorption in the narrow micropores, thus explaining the uptake increase with temperature. Non-continuous micropore size distributions centered at pore widths close to the critical dimensions of the planar form seem to be crucial for a positive evolution of the adsorption capacity with temperature. PMID:25898008

  15. First-principles characterization of formate and carboxyl adsorption on the stoichiometric CeO2(111) and CeO2(110) surfaces

    SciTech Connect

    Mei, Donghai

    2013-05-20

    Molecular adsorption of formate and carboxyl on the stoichiometric CeO2(111) and CeO2(110) surfaces was studied using periodic density functional theory (DFT+U) calculations. Two distinguishable adsorption modes (strong and weak) of formate are identified. The bidentate configuration is more stable than the monodentate adsorption configuration. Both formate and carboxyl bind at the more open CeO2(110) surface are stronger. The calculated vibrational frequencies of two adsorbed species are consistent with experimental measurements. Finally, the effects of U parameters on the adsorption of formate and carboxyl over both CeO2 surfaces were investigated. We found that the geometrical configurations of two adsorbed species are not affected by using different U parameters (U=0, 5, and 7). However, the calculated adsorption energy of carboxyl pronouncedly increases with the U value while the adsorption energy of formate only slightly changes (<0.2 eV). The Bader charge analysis shows the opposite charge transfer occurs for formate and carboxyl adsorption where the adsorbed formate is negatively charge whiled the adsorbed carboxyl is positively charged. Interestingly, with the increasing U parameter, the amount of charge is also increased. This work was supported by the Laboratory Directed Research and Development (LDRD) project of the Pacific Northwest National Laboratory (PNNL) and by a Cooperative Research and Development Agreement (CRADA) with General Motors. The computations were performed using the Molecular Science Computing Facility in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), which is a U.S. Department of Energy national scientific user facility located at PNNL in Richland, Washington. Part of the computing time was also granted by the National Energy Research Scientific Computing Center (NERSC)

  16. Low-coverage adsorption properties of the metal-organic framework MIL-47 studied by pulse chromatography and Monte Carlo simulations.

    PubMed

    Finsy, Vincent; Calero, Sofia; García-Pérez, Elena; Merkling, Patrick J; Vedts, Gill; De Vos, Dirk E; Baron, Gino V; Denayer, Joeri F M

    2009-05-14

    Low-coverage adsorption properties of the metal-organic framework MIL-47 were determined by a combined experimental and simulation study. Henry constants and low coverage adsorption enthalpies of C5-C8 linear and branched alkanes, cyclohexane and benzene were measured from 120 to 240 degrees C using pulse gas chromatography. An adapted force field for linear and branched alkanes in MIL-47 was used to compute the adsorption properties of those molecules. A new set of charges was developed for simulations with benzene in MIL-47. The adsorption enthalpy of linear alkanes increases with about 7.6 kJ mol(-1) per additional -CH2- group. Henry adsorption constants of iso-alkanes are slightly lower than those of the linear chains but the MIL-47 framework is not imposing steric constraints on the branched chains. Benzene and cyclohexane are adsorbed less strongly than n-hexane as they have less hydrogen atoms. For the studied non-polar molecules, the adsorption energies are dominated by van der Waals interactions and benzene adsorption is additionally influenced by Coulombic interactions. The simulated tendencies are in good agreement with the experiments. PMID:19421556

  17. Adsorption of poly(vinyl alcohol) from water to a hydrophobic surface: effects of molecular weight, degree of hydrolysis, salt, and temperature.

    PubMed

    Kozlov, Mikhail; McCarthy, Thomas J

    2004-10-12

    The adsorption of poly(vinyl alcohol) (PVOH) from aqueous solutions to a silicon-supported fluoroalkyl monolayer is described. Thickness, wettability, and roughness of adsorbed films are studied as a function of polymer molecular weight, degree of hydrolysis (from the precursor, poly(vinyl acetate)), polymer concentration, salt type and concentration, and temperature. The data suggest a two-stage process for adsorption of the polymer: physisorption due to a hydrophobic effect (decrease in interfacial free energy) and subsequent stabilization of the adsorbed layer due to crystallization of the polymer. Adsorption of lower-molecular-weight polymers results in thicker films than those prepared with a higher molecular weight; this is ascribed to better crystallization of more mobile short chains. Higher contents of unhydrolyzed acetate groups on the poly(vinyl alcohol) chain lead to thicker adsorbed films. Residual acetate groups partition to the outermost surface of the films and determine wettability. Salts, including sodium chloride and sodium sulfate, promote adsorption, which results in thicker films; at the same time, their presence over a wide concentration range leads to formation of rough coatings. Sodium thiocyanate has little effect on PVOH adsorption, only slightly reducing the thickness in a 2 M salt solution. Increased temperature promotes adsorption in the presence of salt, but has little effect on salt-free solutions. Evidently, higher temperatures favor adsorption but cause crystallization to be less thermodynamically favorable. These competing effects result in the smoothest coatings being formed in an intermediate temperature range. PMID:15461502

  18. Industry Stakeholder Recommendations for DOE's RD&D for Increasing Energy Efficiency in Existing Homes

    SciTech Connect

    Plympton, P.; Dagher, L.; Zwack, B.

    2007-06-01

    This technical report documents feedback for Industry Stakeholders on the direction of future U.S. Department of Energy (DOE) research and development in the area of improving energy efficiency in existing residential buildings.

  19. Sulfur recirculation for increased electricity production in Waste-to-Energy plants.

    PubMed

    Andersson, Sven; Blomqvist, Evalena W; Bäfver, Linda; Jones, Frida; Davidsson, Kent; Froitzheim, Jan; Karlsson, Martin; Larsson, Erik; Liske, Jesper

    2014-01-01

    Sulfur recirculation is a new technology for reducing boiler corrosion and dioxin formation. It was demonstrated in full-scale tests at a Waste to Energy plant in Göteborg (Sweden) during nearly two months of operation. Sulfur was recirculated as sulfuric acid from the flue gas cleaning back to the boiler, thus creating a sulfur loop. The new technology was evaluated by extensive measurement campaigns during operation under normal conditions (reference case) and operation with sulfur recirculation. The chlorine content of both fly ash and boiler ash decreased and the sulfur content increased during the sulfur recirculation tests. The deposit growth and the particle concentration decreased with sulfur recirculation and the dioxin concentration (I-TEQ) of the flue gas was reduced by approximately 25%. Sulfuric acid dew point measurements showed that the sulfuric acid dosage did not lead to elevated SO3 concentrations, which may otherwise induce low temperature corrosion. In the sulfur recirculation corrosion probe exposures, the corrosion rate decreased for all tested materials (16Mo3, Sanicro 28 and Inconel 625) and material temperatures (450 °C and 525 °C) compared to the reference exposure. The corrosion rates were reduced by 60-90%. Sulfur recirculation prevented the formation of transition metal chlorides at the metal/oxide interface, formation of chromate and reduced the presence of zinc in the corrosion products. Furthermore, measured corrosion rates at 525 °C with sulfur recirculation in operation were similar or lower compared to those measured at 450 °C material temperature in reference conditions, which corresponds to normal operation at normal steam temperatures. This implies that sulfur recirculation allows for higher steam data and electricity production without increasing corrosion. PMID:24140194

  20. Adsorption of hydrogen on boron-doped graphene: A first-principles prediction

    SciTech Connect

    Zhou, Yungang; Zu, Xiaotao T.; Gao, Fei; Nie, JL; Xiao, H. Y.

    2009-01-01

    The doping effects of boron on the atomic adsorption of hydrogen on graphene have been investigated using density functional theory calculations. The hydrogen adsorption energies and electronic structures have been considered for pristine and B-doped graphene with the adsorption of hydrogen on top of carbon or boron atom. It is found that the B-doping forms an electron-deficient structure, and decreases the hydrogen adsorption energy dramatically. For the adsorption of hydrogen on top of other sites, similar results also have been found. These results indicate that the hydrogen storage capacity is improved by the doping of B atom.

  1. 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)

  2. Density functional study of the cysteine adsorption on Au nanoclusters

    NASA Astrophysics Data System (ADS)

    Pérez, L. A.; López-Lozano, X.; Garzón, I. L.

    2009-04-01

    The adsorption of the cysteine amino acid (H-SCβH2-CαH-NH2-COOH) on the Au55 cluster is investigated through density functional theory calculations. Two isomers, with icosahedral (Ih) and chiral (C1) geometries, of the Au55 cluster are used to calculate the adsorption energy of the cysteine on different facets of these isomers. Results, only involving the S(thiolate)-Au bonding show that the higher adsorption energies are obtained when the sulfur atom is bonded to an asymmetrical bridge site at the facet containing Au atoms with the lowest coordination of the C1 cluster isomer.

  3. INCREASING YIELDS AND BROADENING MARKETS: PROCESS INNOVATIONS IN THE MANUFACTURING OF ENERGY-SAVING WINDOW GLAZINGS

    SciTech Connect

    Mark Burdis; Neil Sbar

    2005-04-01

    The goal of this project was to develop and implement advanced thin film process technology which would significantly improve the manufacturability of both static and dynamic high performance energy saving coatings for windows. The work done has been aimed at improvements to the process that will result in increases in yield, and this was divided into four main areas, dealing with improvements in substrate preparation methods, reductions in the incidence of problems caused by particulate contamination, use of in-situ optical monitoring to improve process control, and overall system integration to enable simplified, and therefore lower cost operation. Significant progress has been made in each of the areas. In the area of substrate preparation, the enhanced washing techniques which have been developed, in combination with a new inspection technique, have resulted in significant reductions in the number of EC devices which are rejected because of substrate problems. Microscopic inspection of different defects in electrochromic devices showed that many were centered on particles. As a result, process improvements aimed at reducing the incidence of particles throughout the entire process have been implemented. As a result, the average number of defects occurring per unit area has been significantly reduced over the period of this project. The in-situ monitoring techniques developed during this project have become an indispensable part of the processing for EC devices. The deposition of several key layers is controlled as a result of in-situ monitoring, and this has facilitated significant improvements in uniformity and repeatability. Overall system integration has progressed to the stage where the goal of a closed-loop monitoring and control system in within reach, and it is anticipated that this will be achieved during the scale-up phase. There has been a clear increase in the yield occurring over the period of this project (Sept 1999 to September 2003), which is

  4. Insights from the Adsorption of Halide Ions on Graphene Materials.

    PubMed

    Zhu, Chang; Yang, Gang

    2016-08-18

    Graphene has recently found applications in a wide range of fields. Density functional calculations show that halide ions can be adsorbed on pristine graphene, but only F(-) has an appreciable binding energy (-97.0 kJ mol(-1) ). Graphene materials, which are mainly electron donors, can be made strong electron acceptors by edge functionalization with F atoms. The binding strengths of halide ions are greatly enhanced by edge functionalization and show direct proportionality with the degree of functionalization Θ and increased charge transfer. In contrast, the adsorption strengths of metal ions on pristine graphene are clearly superior to those of halide ions but decline substantially with increasing degree of edge functionalization, and for Θ=100 %, the binding energies of -95.7, -44.8, and -25.9 kJ mol(-1) that are calculated for Li(+) , Na(+) , and K(+) , respectively, are obviously inferior to that of F(-) (-186.3 kJ mol(-1) ). Thus, the electronic properties of graphene are fundamentally regulated by edge functionalization, and the preferential adsorption of certain metal ions or anions can be facilely realized by choice of an appropriate degree of functionalization. Adsorbed metal ions and anions behave differently on gradual addition of water molecules, and their binding strengths remain substantial when graphene materials are in the pristine and highly edge functionalized states, respectively. PMID:27127939

  5. Theoretical investigation of methane adsorption onto boron nitride and carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Darvish Ganji, Masoud; Mirnejad, Amir; Najafi, Ali

    2010-08-01

    Methane adsorption onto single-wall boron nitride nanotubes (BNNTs) and carbon nanotubes (CNTs) was studied using the density functional theory within the generalized gradient approximation. The structural optimization of several bonding configurations for a CH4 molecule approaching the outer surface of the (8,0) BNNT and (8,0) CNT shows that the CH4 molecule is preferentially adsorbed onto the CNT with a binding energy of -2.84 kcal mol-1. A comparative study of nanotubes with different diameters (curvatures) reveals that the methane adsorptive capability for the exterior surface increases for wider CNTs and decreases for wider BNNTs. The introduction of defects in the BNNT significantly enhances methane adsorption. We also examined the possibility of binding a bilayer or a single layer of methane molecules and found that methane molecules preferentially adsorb as a single layer onto either BNNTs or CNTs. However, bilayer adsorption is feasible for CNTs and defective BNNTs and requires binding energies of -3.00 and -1.44 kcal mol-1 per adsorbed CH4 molecule, respectively. Our first-principles findings indicate that BNNTs might be an unsuitable material for natural gas storage.

  6. Effect of nitrogen doping of graphene oxide on hydrogen and hydroxyl adsorption

    NASA Astrophysics Data System (ADS)

    Min, Byeong June; Jeong, Hae Kyung

    2014-05-01

    We investigate how nitrogen-doping affects the hydrogen (H) and the hydroxyl (OH) adsorption on graphene oxide (GO) and on nitrogen-doped GO (NGO) via pseudopotential plane wave density functional calculations within the local spin density approximation. We find that the nitrogendoping brings about drastic changes in the hydrogen and the hydroxyl adsorption energetics, but its effects depend sensitively on the nitrogen configuration in NGO. The H and the OH adsorption energies are comparable only for pyrrolic NGO. In GO and quarternary NGO, the H adsorption energy is greater than the OH adsorption energy while the trend is reversed in pyridinic NGO. Also, the OH adsorption process is less affected by nitrogen-doping than the H adsorption is.

  7. Creating an acute energy deficit without stimulating compensatory increases in appetite: is there an optimal exercise protocol?

    PubMed

    Deighton, Kevin; Stensel, David J

    2014-05-01

    Recent years have witnessed significant interest from both the scientific community and the media regarding the influence of exercise on subsequent appetite and energy intake responses. This review demonstrates a consensus among the majority of scientific investigations that an acute bout of land-based endurance exercise does not stimulate any compensatory increases in appetite and energy intake on the day of exercise. Alternatively, preliminary evidence suggests that low volume, supramaximal exercise may stimulate an increase in appetite perceptions during the subsequent hours. In accordance with the apparent insensitivity of energy intake to exercise in the short term, the daily energy balance response to exercise appears to be primarily determined by the energy cost of exercise. This finding supports the conclusions of recent training studies that the energy expenditure of exercise is the strongest predictor of fat loss during an exercise programme. PMID:24717417

  8. Increasing energy coupling into plasma waves by tailoring the laser radial focal spot distribution in a laser wakefield accelerator

    SciTech Connect

    Genoud, G.; Burza, M.; Persson, A.; Svensson, K.; Wahlström, C.-G.; Bloom, M. S.; Najmudin, Z.; Mangles, S. P. D.; Vieira, J.; Silva, L. O.

    2013-06-15

    By controlling the focal spot quality with a deformable mirror, we are able to show that increasing the fraction of pulse energy contained within the central part of the focal spot, while keeping the total energy and central spot size constant, significantly increases the amount of energy transferred to the wakefield: Our measurements show that the laser loses significantly more laser energy and undergoes greater redshifting and that more charge is produced in the accelerated beam. Three dimensional particle in cell simulations performed with accurate representations of the measured focal spot intensity distribution confirm that energy in the wings of the focal spot is effectively wasted. Even though self-focusing occurs, energy in the wings of the focal spot distribution is not coupled into the wakefield, emphasising the vital importance of high quality focal spot profiles in experiments.

  9. Adsorption of mercury on laterite from Guizhou Province, China.

    PubMed

    Yu, Xiaohong; Zhu, Lijun; Guo, Baiwei; He, Shouyang

    2008-01-01

    The adsorption behaviors of Hg(II) on laterite from Guizhou Province, China, were studied and the adsorption mechanism was discussed. The results showed that different mineral compositons in the laterite will cause differences in the adsorption capacity of laterite to Hg(II). Illite and non-crystalloids are the main contributors to enhancing the adsorption capacity of laterite to Hg(II). The pH of the solution is an important factor affecting the adsorption of Hg(II) on laterite. The alkalescent environment (pH 7-9) is favorable to the adsorption of Hg(II). The amount of adsorbed Hg(II) increases with increasing pH. When the pH reaches a certain value, the amount of the adsorbed Hg(II) will reach the maximum level. The amount of adsorbed Hg(II) decreases with increasing pH. The optimal pHs of laterite and kaolinite are 9 and 8, respectively. The optimal initial concentrations of Hg(II) on laterite and kaolinite are 250 and 200 microg/ml, respectively. The adsorption isotherms were described by the Langmuir model. The adsorption of Hg(II) on laterite is a quick process while that of Hg(II) on kaolinite is a slow reaction. Laterite from Guizhou Province is a promising environmental material which can be used in the removal of Hg(II) from wastewater. PMID:19202872

  10. Water Adsorption on Free Cobalt Cluster Cations.

    PubMed

    Kiawi, Denis M; Bakker, Joost M; Oomens, Jos; Buma, Wybren Jan; Jamshidi, Zahra; Visscher, Lucas; Waters, L B F M

    2015-11-01

    Cationic cobalt clusters complexed with water Con(+)-H2O (n = 6-20) are produced through laser ablation and investigated via infrared multiple photon dissociation (IR-MPD) spectroscopy in the 200-1700 cm(-1) spectral range. All spectra exhibit a resonance close to the 1595 cm(-1) frequency of the free water bending vibration, indicating that the water molecule remains intact upon adsorption. For n = 6, the frequency of this band is blue-shifted, but it gradually converges to the free water value with increasing cluster size. In the lower-frequency range (200-650 cm(-1)) the spectra contain several bands which show a very regular frequency evolution, suggesting that the exact cluster geometry has little effect on the water-surface interaction. Density functional theory (DFT) calculations are carried out at the OPBE/TZP level for three representative sizes (n = 6, 9, 13) and indicate that the vibrations responsible for the resonances correspond to bending and torsional modes between the cluster and water moieties. The potential energy surfaces describing these interactions are very shallow, making the calculated harmonic frequencies and IR intensities very sensitive to small geometrical perturbations. We conclude that harmonic frequency calculations on (local) minima structures provide insufficient information for these types of cluster complexes and need to be complemented with calculations that provide a more extensive sampling of the potential energy surface. PMID:26447780

  11. Thermal pollution consequences of the implementation of the president's energy message on increased coal utilization.

    PubMed

    Parker, F L

    1979-12-01

    The thermal consequences of coal utilization are most meaningfully assessed in comparison with the form of power generation replaced by coal which is most likely nuclear. The different effects are influenced by siting decisions and the intrinsic thermal efficiencies of the two fuel systems. Nuclear power plants discharge 50% more waste Rheat to the atmosphere through cooling towers or to a water body than coal-fired plants. Coal-fired plants require about 2/3 as much water as nuclear power plants. Nearly every property of water is affected nonlinearly by temperature, and biological effects may amplify these changes because protein denaturation takes place more rapidly above 30 degrees C and these high temperatures affect bactericidal and viricidal activity of chlorine compounds. Usually algal populations change from a dominance of diatoms and green algae to dominance by blue-green algae. All organisms experience elevated metabolic rates at higher temperatures which may affect total energy needs, foraging ability, reproduction, migration and susceptibility to disease. Intake structures inevitably draw many organisms into the cooling system of a power plant, but the number and kind are influenced by its location, configuration, and mode of operation. Use of water recirculation systems reduces water use and with it, the number of organisms entrained. Mechanical damage in the cooling system to small organisms is generally low, but fish and their larvae and eggs may be seriously damaged. Discharge effects may also be severe but are generally local. The near field, where there are strong shear velocities and rapid temperature changes are particularly stressful to fish, and stringent limitations on the timing and strength of discharges may be required to reduce these stresses to nondamaging levels. Off-stream cooling systems may increase cloudiness, ground fog, precipitation, temperature and local winds, but these effects generally extend no further than 1000 m even in

  12. Thermal pollution consequences of the implementation of the president's energy message on increased coal utilization.

    PubMed Central

    Parker, F L

    1979-01-01

    The thermal consequences of coal utilization are most meaningfully assessed in comparison with the form of power generation replaced by coal which is most likely nuclear. The different effects are influenced by siting decisions and the intrinsic thermal efficiencies of the two fuel systems. Nuclear power plants discharge 50% more waste Rheat to the atmosphere through cooling towers or to a water body than coal-fired plants. Coal-fired plants require about 2/3 as much water as nuclear power plants. Nearly every property of water is affected nonlinearly by temperature, and biological effects may amplify these changes because protein denaturation takes place more rapidly above 30 degrees C and these high temperatures affect bactericidal and viricidal activity of chlorine compounds. Usually algal populations change from a dominance of diatoms and green algae to dominance by blue-green algae. All organisms experience elevated metabolic rates at higher temperatures which may affect total energy needs, foraging ability, reproduction, migration and susceptibility to disease. Intake structures inevitably draw many organisms into the cooling system of a power plant, but the number and kind are influenced by its location, configuration, and mode of operation. Use of water recirculation systems reduces water use and with it, the number of organisms entrained. Mechanical damage in the cooling system to small organisms is generally low, but fish and their larvae and eggs may be seriously damaged. Discharge effects may also be severe but are generally local. The near field, where there are strong shear velocities and rapid temperature changes are particularly stressful to fish, and stringent limitations on the timing and strength of discharges may be required to reduce these stresses to nondamaging levels. Off-stream cooling systems may increase cloudiness, ground fog, precipitation, temperature and local winds, but these effects generally extend no further than 1000 m even in

  13. Small Businesses Save Big: A Borrower's Guide To Increase the Bottom Line Using Energy Efficiency (Fact Sheet)

    SciTech Connect

    Not Available

    2015-01-01

    Dollars saved through energy efficiency can directly impact your bottom line. Whether you are planning for a major renovation or upgrading individual pieces of building equipment, these improvements can help reduce operating costs, save on utility bills, and boost profits. This fact sheet provides a guide for small businesses to find the resources to increase the energy efficiency of their buildings.

  14. Heavy metal adsorption by sulphide mineral surfaces

    NASA Astrophysics Data System (ADS)

    Jean, Gilles E.; Bancroft, G. Michael

    1986-07-01

    The adsorption of aqueous Hg 2+, Pb 2+, Zn 2+ and Cd 2+ complexes on a variety of sulphide minerals has been studied as a function of the solution pH and also as a function of the nature of the ligands in solution. Sulphide minerals are excellent scavengers for these heavy metals. The adsorption is strongly pH dependent, i.e. there is a critical pH at which the adsorption increases dramatically. The pH dependence is related to the hydrolysis of the metal ions. Indirect evidence suggests that the hydrolyzed species are adsorbed directly on the sulphide groups, probably as a monolayer. The results also suggest the presence of MCI n2- n species physisorbed on the adsorbed monolayer. A positive identification of the adsorbed species was not possible using ESCA/XPS.

  15. Albumin adsorption on to aluminium oxide and polyurethane surfaces.

    PubMed

    Sharma, C P; Sunny, M C

    1990-05-01

    The changes in protein adsorption onto aluminium surfaces coated with different thicknesses of oxide layers were examined. The oxide layers on aluminium substrates were derived by the anodizing technique. Protein adsorption studies were conducted using 125I-labelled albumin and the amount of albumin adsorbed was estimated with the help of a gamma counter. An increase in albumin adsorption was observed on oxide layer coated aluminium surfaces. The effect of anti-Hageman factor on albumin and fibrinogen adsorption on to bare aluminium, oxide layer coated aluminium and bare polyether urethane urea surfaces was also investigated. It was observed that the presence of anti-Hageman factor increased the adsorption of albumin and fibrinogen on to all these substrates. PMID:2383620

  16. High capacity adsorption media and method of producing

    DOEpatents

    Tranter, Troy J.; Mann, Nicholas R.; Todd, Terry A.; Herbst, Ronald S.

    2010-10-05

    A method of producing an adsorption medium to remove at least one constituent from a feed stream. The method comprises dissolving and/or suspending at least one metal compound in a solvent to form a metal solution, dissolving polyacrylonitrile into the metal solution to form a PAN-metal solution, and depositing the PAN-metal solution into a quenching bath to produce the adsorption medium. The at least one constituent, such as arsenic, selenium, or antimony, is removed from the feed stream by passing the feed stream through the adsorption medium. An adsorption medium having an increased metal loading and increased capacity for arresting the at least one constituent to be removed is also disclosed. The adsorption medium includes a polyacrylonitrile matrix and at least one metal hydroxide incorporated into the polyacrylonitrile matrix.

  17. High capacity adsorption media and method of producing

    DOEpatents

    Tranter, Troy J.; Herbst, R. Scott; Mann, Nicholas R.; Todd, Terry A.

    2008-05-06

    A method of producing an adsorption medium to remove at least one constituent from a feed stream. The method comprises dissolving at least one metal compound in a solvent to form a metal solution, dissolving polyacrylonitrile into the metal solution to form a PAN-metal solution, and depositing the PAN-metal solution into a quenching bath to produce the adsorption medium. The at least one constituent, such as arsenic, selenium, or antimony, is removed from the feed stream by passing the feed stream through the adsorption medium. An adsorption medium having an increased metal loading and increased capacity for arresting the at least one constituent to be removed is also disclosed. The adsorption medium includes a polyacrylonitrile matrix and at least one metal hydroxide incorporated into the polyacrylonitrile matrix.

  18. Fibrinogen adsorption onto 316L stainless steel, Nitinol and titanium

    NASA Astrophysics Data System (ADS)

    Bai, Zhijun; Filiaggi, M. J.; Dahn, J. R.

    2009-03-01

    Fibrinogen adsorption onto mechanically polished biomedical grade 316L stainless steel (316LSS), nickel titanium alloy (Nitinol) and commercially pure titanium (CpTi) surfaces were studied by measurements of adsorption isotherms and adsorption kinetics using an ex-situ wavelength dispersive spectroscopy technique (WDS). Surface composition, roughness and wettability of these materials were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and water contact angle (WCA) measurements. Adsorption isotherm results showed that surface protein concentration on these materials increased with increasing concentration of fibrinogen in phosphate buffer solution. The fibrinogen adsorption isotherms were modeled by both the monolayer Langmuir isotherm and the multilayer Brunauer-Emmett-Teller (BET) isotherm. The results strongly suggest that fibrinogen forms multilayer structures on these materials when the concentration in solution is high. Complementary measurements on the absorbed fibrinogen films by spectroscopic ellipsometry (SE) support this view.

  19. Energy Sector Vulnerability to Climate Change: Adaptation Options to Increase Resilience (Presentation)

    SciTech Connect

    Newmark, R. L.; Bilello, D.; Macknick, J.; Hallet, K. C.; Anderson, R.; Tidwell, V.; Zamuda, C.

    2013-02-01

    The U.S. Department of Energy is conducting an assessment of vulnerabilities of the U.S. energy sector to climate change and extreme weather. Emphasizing peer reviewed research, it seeks to quantify vulnerabilities and identify specific knowledge or technology gaps. It draws upon a July 2012 workshop, ?Climate Change and Extreme Weather Vulnerability Assessment of the US Energy Sector?, hosted by the Atlantic Council and sponsored by DOE to solicit industry input.

  20. Exhaustively sampling peptide adsorption with metadynamics.

    PubMed

    Deighan, Michael; Pfaendtner, Jim

    2013-06-25

    Simulating the adsorption of a peptide or protein and obtaining quantitative estimates of thermodynamic observables remains challenging for many reasons. One reason is the dearth of molecular scale experimental data available for validating such computational models. We also lack simulation methodologies that effectively address the dual challenges of simulating protein adsorption: overcoming strong surface binding and sampling conformational changes. Unbiased classical simulations do not address either of these challenges. Previous attempts that apply enhanced sampling generally focus on only one of the two issues, leaving the other to chance or brute force computing. To improve our ability to accurately resolve adsorbed protein orientation and conformational states, we have applied the Parallel Tempering Metadynamics in the Well-Tempered Ensemble (PTMetaD-WTE) method to several explicitly solvated protein/surface systems. We simulated the adsorption behavior of two peptides, LKα14 and LKβ15, onto two self-assembled monolayer (SAM) surfaces with carboxyl and methyl terminal functionalities. PTMetaD-WTE proved effective at achieving rapid convergence of the simulations, whose results elucidated different aspects of peptide adsorption including: binding free energies, side chain orientations, and preferred conformations. We investigated how specific molecular features of the surface/protein interface change the shape of the multidimensional peptide binding free energy landscape. Additionally, we compared our enhanced sampling technique with umbrella sampling and also evaluated three commonly used molecular dynamics force fields. PMID:23706011

  1. Oligoclonal antibody targeting ghrelin increases energy expenditure and reduces food intake in fasted mice

    PubMed Central

    Zakhari, Joseph S.; Zorrilla, Eric P.; Zhou, Bin; Mayorov, Alexander V.; Janda, Kim D.

    2011-01-01

    Ghrelin, an enteric peptide hormone linked to the pathophysiology of obesity has been a therapeutic target of great interest over the past decade. Many research efforts have focused on the antagonism of ghrelin’s endogenous receptor GHSR1a, which is found along ascending vagal afferent fibers, as well as in the arcuate nucleus of the hypothalamus. Additionally, peptidic inhibitors against ghrelin O-acyltransferase, the enzyme responsible for the paracrine activation of ghrelin, have recently been studied. Our research has taken an alternative immunological approach, studying both active and passive vaccination as a means to sequester ghrelin in the periphery, with the original discovery in rat of decreased feed efficiency and adiposity, as well as increased metabolic activity. Using our previous hapten designs as a stepping-stone, three monoclonal antibodies (JG2, JG3, and JG4) were procured against ghrelin and tested in vivo. While mAb JG4 had the highest affinity for ghrelin, it failed to attenuate the orexigenic effects of food deprivation on energy metabolism or food intake in mice. However, animals that were administered a combination of JG3:JG4, (termed a doublet), or JG2:JG3:JG4, (termed a triplet), demonstrated higher heat dispersion and rate of respiration (higher CO2 emission and O2 consumption) during a 24-hr fast refeed. Mice administered the triplet cocktail of JG2:JG3:JG4 also demonstrated decreased food intake upon refeeding as compared to control animals. Recently, Lu and colleagues reported that a passive approach using a single, high affinity N-terminally directed monoclonal antibody did not abrogate the effects of endogenous ghrelin. Our current report corroborates this finding, yet, refutes that a monoclonal antibody approach cannot be efficacious. Rather, we find that a multiple monoclonal antibody (oligoclonal) approach can reproduce the underlying logic to previously reported efficacies using active vaccinations. PMID:22149064

  2. Hydrogen adsorption on sulphur-doped SiC nanotubes

    NASA Astrophysics Data System (ADS)

    Sevak Singh, Ram

    2016-07-01

    Hydrogen (H2) is an energy carrier and clean fuel that can be used for a broad range of applications that include fuel cell vehicles. Therefore, development of materials for hydrogen storage is demanded. Nanotubes, in this context, are appropriate materials. Recently, silicon carbide nanotube (SiCNTs) have been predicted as potential nanomaterials for hydrogen storage, and atomic doping into the nanotubes improves the H2 adsorption. Here, we report H2 adsorption properties of sulphur-doped (S-doped) SiCNTs using first-principles calculations based on density functional theory. The H2 adsorption properties are investigated by calculations of energy band structures, density of states (DOS), adsorption energy and Mulliken charge population analysis. Our findings show that, compared to the intrinsic SiCNT, S-doped SiCNT is more sensitive to H2 adsorption. H2 gas adsorption on S-doped C-sites of SiCNT brings about significant modulation of the electronic structure of the nanotube, which results in charge transfer from the nanotube to the gas, and dipole–dipole interactions cause chemisorptions of hydrogen. However, in the case of H2 gas adsorption on S-doped Si-sites of the nanotube, lesser charge transfer from the nanotube to the gas results in physisorptions of the gas. The efficient hydrogen sensing properties of S-doped SiCNTs, studied here, may have potential for its practical realization for hydrogen storage application.

  3. Ozone adsorption on carbon nanoparticles

    NASA Astrophysics Data System (ADS)

    Chassard, Guillaume; Gosselin, Sylvie; Visez, Nicolas; Petitprez, Denis

    2014-05-01

    realized by selecting the particles size with a differential mobility analyser. We observed a strong size-dependent increase in reactivity with the decrease of particles size. This result is relevant for the health issues. Indeed the smallest particles are most likely to penetrate deep into the lungs. Competitive reactions between ozone and other species like H2O or atomic oxygen were also considered. Oxygen atoms were generated by photolysis of O3 (or O2) and were chosen because it is believed to form the same reactive oxygen intermediates than ozone. A weak water physisorption on soot was observed revealing hydrophobic properties of particles. Oxygen atoms were found to be strongly reactive. A Langmuir behavior was observed for oxygen atoms adsorption on carbon particles and we were able to determine an initial uptake coefficient of approximately 2.10-2. [1] Fenidel, W., et al., Interaction between carbon or iron aerosol particles and ozone. Atmospheric Environment, 1995. 29(9): p. 967-973. [2] Smith, D. and A. Chughtai, Reaction kinetics of ozone at low concentrations with n-hexane soot. Journal of geophysical research, 1996. 101(D14): p. 19607-19,620. [3] Kamm, S., et al., The heterogeneous reaction of ozone with soot aerosol. Atmospheric Environment, 1999. 33(28): p. 4651-4661. [4] Stephens, S., M.J. Rossi, and D.M. Golden, The heterogeneous reaction of ozone on carbonaceous surfaces. International journal of chemical kinetics, 1986. 18(10): p. 1133-1149. [5] Pöschl, U., et al., Interaction of ozone and water vapor with spark discharge soot aerosol particles coated with benzo [a] pyrene: O3 and H2O adsorption, benzo [a] pyrene degradation, and atmospheric implications. The Journal of Physical Chemistry A, 2001. 105(16): p. 4029-4041.

  4. Adsorption kinetics, isotherms and thermodynamics of atrazine removal using a banana peel based sorbent.

    PubMed

    Chaparadza, Allen; Hossenlopp, Jeanne M

    2012-01-01

    Atrazine removal from water by treated banana peels was studied. The effect of pH, contact time, initial atrazine concentration, and temperature were investigated. Batch experiments demonstrated that 15 g L(-1) adsorbent dosage removed 90-99% of atrazine from 1-150 ppm aqueous solutions. The removal was both pH and temperature dependent with the most atrazine removed between pH 7 and 8.2 and increased with increasing temperature. Equilibrium data fitted well to the Langmuir and Redlich-Peterson models in the concentration and temperature ranges investigated, with a maximum adsorption capacity of 14 mg g(-1). Simple mass transfer models were applied to the experimental data to examine the adsorption mechanism and it was found that both external mass transfer and intraparticle diffusion played important roles in the adsorption mechanisms. The enthalpy of atrazine adsorption was evaluated to be 67.8 ± 6.3 kJ mol(-l) with a Gibbs free energy of -5.7 ± 1.2 kJ mol(-1). PMID:22339031

  5. Protein adsorption to multi-component glasses

    NASA Astrophysics Data System (ADS)

    Hall, Matthew Micah

    2003-07-01

    The adsorption of human serum albumin (HSA) to sodium silicate, soda lime silicate (SLS), and sodium aluminosilicate (SAS) glass microspheres was investigated using sodiumdodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in conjunction with a colloidal silver stain for visualization. The 30 Na2O·70 SiO2 composition could not be evaluated due to an apparent chemical interference that occurred during silver staining. This inhibitory effect was attributed to the extensive corrosion that occurred during the protein elution and caused an elevation in the pH of the solution. The remaining glass compositions were sufficiently durable for further study. The HSA adsorption capacity of SLS glass microspheres containing 70 and 80 mol% SiO2 increased as CaO was substituted for Na2O. An abrupt decrease in the HSA adsorption capacity was observed for SLS glasses containing 60 mol% SiO2. A similar trend was observed for the SAS glass microspheres, although the SAS glasses adsorbed less HSA than the SLS glasses containing equivalent molar percentages of SiO2. The initial increase in HSA adsorption capacity for SLS and SAS glasses containing 70 and 80 MOM SiO2 was attributed to the introduction of positive charges into the glass surfaces via Ca2+ and Al3+ cations. The decrease in HSA adsorption capacity for SLS and SAS glasses containing 60 mol% SiO2 may be due to an enhanced affinity between the glasses and HSA, resulting in a "flattened" conformation that limits the total accessible area for adsorption.

  6. Adsorption of antimony onto iron oxyhydroxides: adsorption behavior and surface structure.

    PubMed

    Guo, Xuejun; Wu, Zhijun; He, Mengchang; Meng, Xiaoguang; Jin, Xin; Qiu, Nan; Zhang, Jing

    2014-07-15

    Antimony is detected in soil and water with elevated concentration due to a variety of industrial applications and mining activities. Though antimony is classified as a pollutant of priority interest by the United States Environmental Protection Agency (USEPA) and Europe Union (EU), very little is known about its environmental behavior and adsorption mechanism. In this study, the adsorption behaviors and surface structure of antimony (III/V) on iron oxides were investigated using batch adsorption techniques, surface complexation modeling (SCM), X-ray photon spectroscopy (XPS) and extended X-ray absorption fine structure spectroscopy (EXAFS). The adsorption isotherms and edges indicated that the affinity of Sb(V) and Sb(III) toward the iron oxides depended on the Sb species, solution pH, and the characteristics of iron oxides. Sb(V) adsorption was favored at acidic pH and decreased dramatically with increasing pH, while Sb(III) adsorption was constant over a broad pH range. When pH is higher than 7, Sb(III) adsorption by goethite and hydrous ferric oxide (HFO) was greater than Sb(V). EXAFS analysis indicated that the majority of Sb(III), either adsorbed onto HFO or co-precipitated by FeCl3, was oxidized into Sb(V) probably due to the involvement of O2 in the long duration of sample preservation. Only one Sb-Fe subshell was filtered in the EXAFS spectra of antimony adsorption onto HFO, with the coordination number of 1.0-1.9 attributed to bidentate mononuclear edge-sharing ((2)E) between Sb and HFO. PMID:24910911

  7. Molecular Simulations of Adsorption and Diffusion of RDX in IRMOF-1

    SciTech Connect

    Xong, Ruichang Xong; Fern, Jared T.; Keffer, David J.; Fuentes-Cabrera, Miguel A; Nicholson, Don M

    2009-01-01

    In order to test the feasibility of using metal-organic frameworks (MOFs) to pre-concentrate explosive molecules for detection, molecular simulations of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) within IRMOF-1 were performed. Grand canonical Monte Carlo (GCMC) simulations were used to generate adsorption isotherms for pure RDX, RDX in dry air, and RDX in wet air. In addition to the isotherms, the GCMC simulations provide adsorption energies and density distributions of the adsorbates within the MOF. Molecular dynamics simulations calculate diffusivities and provide a detailed understanding of the change in conformation of the RDX molecule upon adsorption. The presence of dry air has little influence on the amount of RDX that adsorbs. The presence of wet air increases the amount of RDX that adsorbs due to favorable interactions between RDX and water. We found a Henry's law constant of 21.2 mol/kg/bar for both pure RDX and RDX in dry air. The RDX adsorption sites are located (i) in big cages, (ii) near a vertex, and (iii) between benzene rings. The energy of adsorption of RDX at infinite dilution was found to be - 9.2 kcal/mol. The distributions of bond lengths, bond angles and torsion angles in RDX are uniformly slightly broader in the gas phase than in the adsorbed phase, but not markedly so. The self-diffusivity of RDX in IRMOF-1 is a strong function of temperature, with an activation energy of 6.0 kcal/mol.

  8. Irreversible adsorption of particles on heterogeneous surfaces.

    PubMed

    Adamczyk, Zbigniew; Jaszczółt, Katarzyna; Michna, Aneta; Siwek, Barbara; Szyk-Warszyńska, Lilianna; Zembala, Maria

    2005-12-30

    Methods of theoretical and experimental evaluation of irreversible adsorption of particles, e.g., colloids and globular proteins at heterogeneous surfaces were reviewed. The theoretical models were based on the generalized random sequential adsorption (RSA) approach. Within the scope of these models, localized adsorption of particles occurring as a result of short-ranged attractive interactions with discrete adsorption sites was analyzed. Monte-Carlo type simulations performed according to this model enabled one to determine the initial flux, adsorption kinetics, jamming coverage and the structure of the particle monolayer as a function of the site coverage and the particle/site size ratio, denoted by lambda. It was revealed that the initial flux increased significantly with the site coverage theta(s) and the lambda parameter. This behavior was quantitatively interpreted in terms of the scaled particle theory. It also was demonstrated that particle adsorption kinetics and the jamming coverage increased significantly, at fixed site coverage, when the lambda parameter increased. Practically, for alpha = lambda2theta(s) > 1 the jamming coverage at the heterogeneous surfaces attained the value pertinent to continuous surfaces. The results obtained prove unequivocally that spherically shaped sites were more efficient in binding particles in comparison with disk-shaped sites. It also was predicted that for particle size ratio lambda < 4 the site multiplicity effect plays a dominant role, affecting significantly the structure of particle monolayers and the jamming coverage. Experimental results validating main aspects of these theoretical predictions also have been reviewed. These results were derived by using monodisperse latex particles adsorbing on substrates produced by covering uniform surface by adsorption sites of a desired size, coverage and surface charge. Particle deposition occurred under diffusion-controlled transport conditions and their coverage was

  9. Fundamentals of high pressure adsorption

    SciTech Connect

    Zhou, Y.P.; Zhou, L.

    2009-12-15

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

  10. GLP-1(32-36)amide Pentapeptide Increases Basal Energy Expenditure and Inhibits Weight Gain in Obese Mice.

    PubMed

    Tomas, Eva; Stanojevic, Violeta; McManus, Karen; Khatri, Ashok; Everill, Paul; Bachovchin, William W; Habener, Joel F

    2015-07-01

    The prevalence of obesity-related diabetes is increasing worldwide. Here we report the identification of a pentapeptide, GLP-1(32-36)amide (LVKGRamide), derived from the glucoincretin hormone GLP-1, that increases basal energy expenditure and curtails the development of obesity, insulin resistance, diabetes, and hepatic steatosis in diet-induced obese mice. The pentapeptide inhibited weight gain, reduced fat mass without change in energy intake, and increased basal energy expenditure independent of physical activity. Analyses of tissues from peptide-treated mice reveal increased expression of UCP-1 and UCP-3 in brown adipose tissue and increased UCP-3 and inhibition of acetyl-CoA carboxylase in skeletal muscle, findings consistent with increased fatty acid oxidation and thermogenesis. In palmitate-treated C2C12 skeletal myotubes, GLP-1(32-36)amide activated AMPK and inhibited acetyl-CoA carboxylase, suggesting activation of fat metabolism in response to energy depletion. By mass spectroscopy, the pentapeptide is rapidly formed from GLP-1(9-36)amide, the major form of GLP-1 in the circulation of mice. These findings suggest that the reported insulin-like actions of GLP-1 receptor agonists that occur independently of the GLP-1 receptor might be mediated by the pentapeptide, and the previously reported nonapeptide (FIAWLVKGRamide). We propose that by increasing basal energy expenditure, GLP-1(32-36)amide might be a useful treatment for human obesity and associated metabolic disorders. PMID:25858562

  11. GLP-1(32-36)amide Pentapeptide Increases Basal Energy Expenditure and Inhibits Weight Gain in Obese Mice

    PubMed Central

    Tomas, Eva; Stanojevic, Violeta; McManus, Karen; Khatri, Ashok; Everill, Paul; Bachovchin, William W.

    2015-01-01

    The prevalence of obesity-related diabetes is increasing worldwide. Here we report the identification of a pentapeptide, GLP-1(32-36)amide (LVKGRamide), derived from the glucoincretin hormone GLP-1, that increases basal energy expenditure and curtails the development of obesity, insulin resistance, diabetes, and hepatic steatosis in diet-induced obese mice. The pentapeptide inhibited weight gain, reduced fat mass without change in energy intake, and increased basal energy expenditure independent of physical activity. Analyses of tissues from peptide-treated mice reveal increased expression of UCP-1 and UCP-3 in brown adipose tissue and increased UCP-3 and inhibition of acetyl-CoA carboxylase in skeletal muscle, findings consistent with increased fatty acid oxidation and thermogenesis. In palmitate-treated C2C12 skeletal myotubes, GLP-1(32-36)amide activated AMPK and inhibited acetyl-CoA carboxylase, suggesting activation of fat metabolism in response to energy depletion. By mass spectroscopy, the pentapeptide is rapidly formed from GLP-1(9-36)amide, the major form of GLP-1 in the circulation of mice. These findings suggest that the reported insulin-like actions of GLP-1 receptor agonists that occur independently of the GLP-1 receptor might be mediated by the pentapeptide, and the previously reported nonapeptide (FIAWLVKGRamide). We propose that by increasing basal energy expenditure, GLP-1(32-36)amide might be a useful treatment for human obesity and associated metabolic disorders. PMID:25858562

  12. Social Status and the Differential Impacts of Increasing Energy Costs on Families in Mississippi. Final Report.

    ERIC Educational Resources Information Center

    Lang, Marvel; Smith, James C.

    Research was undertaken to determine how differences in social status among various segments of the population in Mississippi contribute to differences in household energy costs and how socioeconomic differences coupled with social status have impact on energy consumption behavior. Two samples of the state's population were used for comparative…

  13. Increased Protein Maintains Nitrogen Balance during Exercise-Induced Energy Deficit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    PURPOSE: This study examined how a high-protein diet affected nitrogen balance and protein turnover during an exercise-induced energy deficit. METHODS: Twenty-two men completed a 4-d (D1-4) baseline period (BL) of an energy balance diet while maintaining usual physical activity level, followed by 7 ...

  14. Adsorption of charged and neutral polymer chains on silica surfaces: The role of electrostatics, volume exclusion, and hydrogen bonding

    NASA Astrophysics Data System (ADS)

    Spruijt, Evan; Biesheuvel, P. M.; de Vos, Wiebe M.

    2015-01-01

    We develop an off-lattice (continuum) model to describe the adsorption of neutral polymer chains and polyelectrolytes to surfaces. Our continuum description allows taking excluded volume interactions between polymer chains and ions directly into account. To implement those interactions, we use a modified hard-sphere equation of state, adapted for mixtures of connected beads. Our model is applicable to neutral, charged, and ionizable surfaces and polymer chains alike and accounts for polarizability effects of the adsorbed layer and chemical interactions between polymer chains and the surface. We compare our model predictions to data of a classical system for polymer adsorption: neutral poly(N -vinylpyrrolidone) (PVP) on silica surfaces. The model shows that PVP adsorption on silica is driven by surface hydrogen bonding with an effective maximum binding energy of about 1.3 kBT per PVP segment at low p H . As the p H increases, the Si-OH groups become increasingly dissociated, leading to a lower capacity for H bonding and simultaneous counterion accumulation and volume exclusion close to the surface. Together these effects result in a characteristic adsorption isotherm, with the adsorbed amount dropping sharply at a critical p H . Using this model for adsorption data on silica surfaces cleaned by either a piranha solution or an O2 plasma, we find that the former have a significantly higher density of silanol groups.

  15. Monte Carlo Simulations Probing the Adsorptive Separation of Hydrogen Sulfide/Methane Mixtures Using All-Silica Zeolites.

    PubMed

    Shah, Mansi S; Tsapatsis, Michael; Siepmann, J Ilja

    2015-11-10

    Selective removal of hydrogen sulfide (H2S) from sour natural gas mixtures is one of the key challenges facing the natural gas industry. Adsorption and pervaporation processes utilizing nanoporous materials, such as zeolites, can be alternatives to highly energy-intensive amine-based absorption processes. In this work, the adsorption behavior of binary mixtures containing H2S and methane (CH4) in seven different all-silica zeolite frameworks (CHA, DDR, FER, IFR, MFI, MOR, and MWW) is investigated using Gibbs ensemble Monte Carlo simulations at two temperatures (298 and 343 K) and pressures ranging from 1 to 50 bar. The simulations demonstrate high selectivities that, with the exception of MOR, increase with increasing H2S concentration due to favorable sorbate-sorbate interactions. The simulations indicate significant inaccuracies of predictions using unary adsorption data and ideal adsorbed solution theory. In addition, the adsorption of binary H2S/H2O mixtures in MFI is considered to probe whether the presence of H2S induces coadsorption and reduces the hydrophobic character of all-silica zeolites. The simulations show preferential adsorption of H2S from moist gases with a selectivity of about 18 over H2O. PMID:26473306

  16. Comparison of 4-chloro-2-nitrophenol adsorption on single-walled and multi-walled carbon nanotubes

    PubMed Central

    2012-01-01

    The adsorption characteristics of 4-chloro-2-nitrophenol (4C2NP) onto single-walled and multi-walled carbon nanotubes (SWCNTs and MWCNTs) from aqueous solution were investigated with respect to the changes in the contact time, pH of solution, carbon nanotubes dosage and initial 4C2NP concentration. Experimental results showed that the adsorption efficiency of 4C2NP by carbon nanotubes (both of SWCNTs and MWCNTs) increased with increasing the initial 4C2NP concentration. The maximum adsorption took place in the pH range of 2–6. The linear correlation coefficients of different isotherm models were obtained. Results revealed that the Langmuir isotherm fitted the experimental data better than the others and based on the Langmuir model equation, maximum adsorption capacity of 4C2NP onto SWCNTs and MWCNTs were 1.44 and 4.42 mg/g, respectively. The observed changes in the standard Gibbs free energy, standard enthalpy and standard entropy showed that the adsorption of 4C2NP onto SWCNTs and MWCNTs is spontaneous and exothermic in the temperature range of 298–328 K. PMID:23369489

  17. Adsorption and desorption characteristics of arsenic onto ceria nanoparticles

    NASA Astrophysics Data System (ADS)

    Feng, Qinzhong; Zhang, Zhiyong; Ma, Yuhui; He, Xiao; Zhao, Yuliang; Chai, Zhifang

    2012-01-01

    The rapid increase in the use of engineered nanoparticles [ENPs] has resulted in an increasing concern over the potential impacts of ENPs on the environmental and human health. ENPs tend to adsorb a large variety of toxic chemicals when they are emitted into the environment, which may enhance the toxicity of ENPs and/or adsorbed chemicals. The study was aimed to investigate the adsorption and desorption behaviors of arsenic on ceria NPs in aqueous solution using batch technique. Results show that the adsorption behavior of arsenic on ceria NPs was strongly dependent on pH and independent of ionic strength, indicating that the electrostatic effect on the adsorption of these elements was relatively not important compared to surface chemical reactions. The adsorption isotherms fitted very well to both the Langmuir and Freundlich models. The thermodynamic parameters (Δ H 0 , Δ S 0 , and Δ G 0 ) for the adsorption of arsenic were determined at three different temperatures of 283, 303, and 323 K. The adsorption reaction was endothermic, and the process of adsorption was favored at high temperature. The desorption data showed that desorption hysteresis occurred at the initial concentration studied. High adsorption capacity of arsenic on ceria NPs suggests that the synergistic effects of ceria NPs and arsenic on the environmental systems may exist when they are released into the environment.

  18. Adsorption of oleic acid at sillimanite/water interface.

    PubMed

    Kumar, T V Vijaya; Prabhakar, S; Raju, G Bhaskar

    2002-03-15

    The interaction of oleic acid at sillimanite-water interface was studied by adsorption, FT-IR, and zeta potential measurements. The isoelectric point (IEP) of sillimanite obtained at pH 8.0 was found to shift in the presence of oleic acid. This shift in IEP was attributed to chemisorption of oleic acid on sillimanite. Adsorption experiments were conducted at pH 8.0, where the sillimanite surface is neutral. The adsorption isotherm exhibited a plateau around 5 micromol/m2 that correspond to a monolayer formation. Adsorption of oleic acid on sillimanite, alumina, and aluminum hydroxide was studied by FT-IR. Chemisorption of oleic acid on the above substrates was confirmed by FT-IR studies. Hydroxylation of mineral surface was found to be essential for the adsorption of oleic acid molecules. These surface hydroxyl sites were observed to facilitate deprotonation of oleic acid and its subsequent adsorption. Thus protons from oleic acid react with surface hydroxyl groups and form water molecules. Based on the experimental results, the mechanism of oleic acid adsorption on mineral substrate was proposed. Free energy of adsorption was estimated using the Stern-Graham equation for a sillimanite-oleate system. PMID:16290466

  19. Increased air temperature during simulated autumn conditions does not increase photosynthetic carbon gain but affects the dissipation of excess energy in seedlings of the evergreen conifer Jack pine.

    PubMed

    Busch, Florian; Hüner, Norman P A; Ensminger, Ingo

    2007-03-01

    Temperature and daylength act as environmental signals that determine the length of the growing season in boreal evergreen conifers. Climate change might affect the seasonal development of these trees, as they will experience naturally decreasing daylength during autumn, while at the same time warmer air temperature will maintain photosynthesis and respiration. We characterized the down-regulation of photosynthetic gas exchange and the mechanisms involved in the dissipation of energy in Jack pine (Pinus banksiana) in controlled environments during a simulated summer-autumn transition under natural conditions and conditions with altered air temperature and photoperiod. Using a factorial design, we dissected the effects of daylength and temperature. Control plants were grown at either warm summer conditions with 16-h photoperiod and 22 degrees C or conditions representing a cool autumn with 8 h/7 degrees C. To assess the impact of photoperiod and temperature on photosynthesis and energy dissipation, plants were also grown under either cold summer (16-h photoperiod/7 degrees C) or warm autumn conditions (8-h photoperiod/22 degrees C). Photosynthetic gas exchange was affected by both daylength and temperature. Assimilation and respiration rates under warm autumn conditions were only about one-half of the summer values but were similar to values obtained for cold summer and natural autumn treatments. In contrast, photosynthetic efficiency was largely determined by temperature but not by daylength. Plants of different treatments followed different strategies for dissipating excess energy. Whereas in the warm summer treatment safe dissipation of excess energy was facilitated via zeaxanthin, in all other treatments dissipation of excess energy was facilitated predominantly via increased aggregation of the light-harvesting complex of photosystem II. These differences were accompanied by a lower deepoxidation state and larger amounts of beta-carotene in the warm autumn

  20. Extracorporeal adsorption of endotoxin.

    PubMed

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

    1997-02-01

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

  1. The effects of feeding increasing concentrations of corn oil on energy metabolism and nutrient balance in finishing beef steers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of added fat source is common in high-concentrate finishing diets. The objective of our experiment was to determine if feeding increasing concentrations of added dietary corn oil would decrease enteric methane production, increase the ME:DE ratio, and improve retained energy in finishing be...

  2. 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.

  3. Adsorption--from theory to practice.

    PubMed

    Dabrowski, A

    2001-10-01

    Adsorption at various interfaces has concerned scientists since the beginning of this century. This phenomenon underlies a number of extremely important processes of utilitarian significance. The technological, environmental and biological importance of adsorption can never be in doubt. Its practical applications in industry and environmental protection are of paramount importance. The adsorption of substrates is the first stage in many catalytic processes. The methods for separation of mixtures on a laboratory and on an industrial scale are increasingly based on utilising the change in concentration of components at the interface. Moreover, such vital problems as purification of water, sewages, air and soil are involved here too. On the other hand, many areas in which technological innovation has covered adsorption phenomena have been expanded more through art and craft than through science. A basic understanding of the scientific principles is far behind; in part because the study of interfaces requires extremely careful experimentation if meaningful and reproducible results are to be obtained. In recent years, however, considerable effort has been increasingly directed toward closing the gap between theory and practice. Crucial progress in theoretical description of the adsorption has been achieved, mainly through the development of new theoretical approaches formulated on a molecular level, by means of computer simulation methods and owing to new techniques which examine surface layers or interfacial regions. Moreover, during the last 15 years new classes of solid adsorbents have been developed, such as activated carbon fibres and carbon molecular sieves, fullerenes and heterofullerenes, microporous glasses and nanoporous--both carbonaceous and inorganic--materials. Nanostructured solids are very popular in science and technology and have gained extreme interest due to their sorption, catalytic, magnetic, optical and thermal properties. Although the development

  4. Adsorption edge study about cadmium, copper, nickel and zinc adsorption by variable charge soils

    NASA Astrophysics Data System (ADS)

    Casagrande, J. C.; Mouta, E. R.; Soares, M. R.

    2009-04-01

    The improper discharge of industrial and urban residues and the inadvertent use of fertilizers and pesticides can result in soil and water pollution and improve the potential of trace metals to enter in the human food chain. Adsorption reactions occur at the solid/liquid interface and are the most important mechanisms for controlling the activity of metal ions in soil solution. In a complex system with amphoteric behavior, the comprehension of the mobility, availability and fate of pollutants in the soil system is crucial for the prediction of the environmental consequences and for development of prevention/remediation strategies. A comparative study of cadmium (Cd), copper (Cu), nickel (Ni) and zinc (Zn) adsorption by highly weathered soils was carried out. Surface (0-0.2m) and subsoil (B horizon) samples were taken from a Rhodic Kandiudalf (RH), an Anionic "Xanthic" Acrudox (XA) and an Anionic "Rhodic" Acrudox (RA), located in brazilian humid tropical area. As the pH and the ionic strength are important environmental factors influencing the solution chemistry of heavy metals in variable charge systems, adsorption envelopes, in a batch adsorption experiment, were elaborated by reacting, for 24 h, soil samples with individual 0.01, 0.1 and 1.0 mol L-1 Ca(NO3)2 aqueous solutions containing nitrate salts of the adsorptive heavy metal (Cd, Cu, Ni and Zn) at the initial concentration of 5 mg L-1, with an increasing pH value from 3.0 to 8.0. pH50-100%, the difference between the pH of 100 and 50 percent metal adsorption was determined. A sharp increase of adsorption density (adsorption edge) was observed within a very narrow pH range, usually less than two pH units. Commonly, the relative affinity of a soil for a metal cation increases with the tendency of the cation to form inner-sphere surface complexes. This may be caused by differences in extent of hydrolysis of Cu ions and in affinity of adsorption sites for Cu. In general, subsurface samples showed low pH50

  5. Understanding pH Effects on Trichloroethylene and Perchloroethylene Adsorption to Iron in Permeable Reactive Barriers for Groundwater Remediation.

    PubMed

    Luo, Jing; Farrell, James

    2013-01-01

    Metallic iron filings are becoming increasing used in permeable reactive barriers for remediating groundwater contaminated by chlorinated solvents. Understanding solution pH effects on rates of reductive dechlorination in permeable reactive barriers is essential for designing remediation systems that can meet treatment objectives under conditions of varying groundwater properties. The objective of this research was to investigate how the solution pH value affects adsorption of trichloroethylene (TCE) and perchloroethylene (PCE) on metallic iron surfaces. Because adsorption is first required before reductive dechlorination can occur, pH effects on halocarbon adsorption energies may explain pH effects on dechlorination rates. Adsorption energies for TCE and PCE were calculated via molecular mechanics simulations using the Universal force field and a self-consistent reaction field charge equilibration scheme. A range in solution pH values was simulated by varying the amount of atomic hydrogen adsorbed on the iron. The potential energies associated TCE and PCE complexes were dominated by electrostatic interactions, and complex formation with the surface was found to result in significant electron transfer from the iron to the adsorbed halocarbons. Adsorbed atomic hydrogen was found to lower the energies of TCE complexes more than those for PCE. Attractions between atomic hydrogen and iron atoms were more favorable when TCE versus PCE was adsorbed to the iron surface. These two findings are consistent with the experimental observation that changes in solution pH affect TCE reaction rates more than those for PCE. PMID:23626602

  6. Understanding pH Effects on Trichloroethylene and Perchloroethylene Adsorption to Iron in Permeable Reactive Barriers for Groundwater Remediation

    PubMed Central

    Luo, Jing; Farrell, James

    2013-01-01

    Metallic iron filings are becoming increasing used in permeable reactive barriers for remediating groundwater contaminated by chlorinated solvents. Understanding solution pH effects on rates of reductive dechlorination in permeable reactive barriers is essential for designing remediation systems that can meet treatment objectives under conditions of varying groundwater properties. The objective of this research was to investigate how the solution pH value affects adsorption of trichloroethylene (TCE) and perchloroethylene (PCE) on metallic iron surfaces. Because adsorption is first required before reductive dechlorination can occur, pH effects on halocarbon adsorption energies may explain pH effects on dechlorination rates. Adsorption energies for TCE and PCE were calculated via molecular mechanics simulations using the Universal force field and a self-consistent reaction field charge equilibration scheme. A range in solution pH values was simulated by varying the amount of atomic hydrogen adsorbed on the iron. The potential energies associated TCE and PCE complexes were dominated by electrostatic interactions, and complex formation with the surface was found to result in significant electron transfer from the iron to the adsorbed halocarbons. Adsorbed atomic hydrogen was found to lower the energies of TCE complexes more than those for PCE. Attractions between atomic hydrogen and iron atoms were more favorable when TCE versus PCE was adsorbed to the iron surface. These two findings are consistent with the experimental observation that changes in solution pH affect TCE reaction rates more than those for PCE. PMID:23626602

  7. Binding of Trivalent Arsenic onto the Tetrahedral Au20 and Au19Pt Clusters: Implications in Adsorption and Sensing.

    PubMed

    Cortés-Arriagada, Diego; Oyarzún, María Paz; Sanhueza, Luis; Toro-Labbé, Alejandro

    2015-07-01

    The interaction of arsenic(III) onto the tetrahedral Au20 cluster was studied computationally to get insights into the interaction of arsenic traces (presented in polluted waters) onto embedded electrodes with gold nanostructures. Pollutant interactions onto the vertex, edge, or inner gold atoms of Au20 were observed to have a covalent character by forming metal-arsenic or metal-oxygen bonding, with adsorption energies ranging from 0.5 to 0.8 eV, even with a stable physisorption; however, in aqueous media, the Au-vertex-pollutant interaction was found to be disadvantageous. The substituent effect of a platinum atom onto the Au20 cluster was evaluated to get insights into the changes in the adsorption and electronic properties of the adsorbent-adsorbate systems due to chemical doping. It was found that the dopant atom increases both the metal-pollutant adsorption energy and stability onto the support in a water media for all interaction modes; adsorption energies were found to be in a range of 0.6 to 1.8 eV. All interactions were determined to be accompanied by electron transfer as well as changes in the local reactivity that determine the amount of transferred charge and a decrease in the HOMO-LUMO energy gap with respect to the isolated substrate. PMID:26061641

  8. A pressure-amplifying framework material with negative gas adsorption transitions.

    PubMed

    Krause, Simon; Bon, Volodymyr; Senkovska, Irena; Stoeck, Ulrich; Wallacher, Dirk; Többens, Daniel M; Zander, Stefan; Pillai, Renjith S; Maurin, Guillaume; Coudert, François-Xavier; Kaskel, Stefan

    2016-04-21

    Adsorption-based phenomena are important in gas separations, such as the treatment of greenhouse-gas and toxic-gas pollutants, and in water-