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Sample records for non-electrostatic surface complexation

  1. Development of a Composite Non-Electrostatic Surface Complexation Model Describing Plutonium Sorption to Aluminosilicates

    Energy Technology Data Exchange (ETDEWEB)

    Powell, B A; Kersting, A; Zavarin, M; Zhao, P

    2008-10-28

    Due to their ubiquity in nature and chemical reactivity, aluminosilicate minerals play an important role in retarding actinide subsurface migration. However, very few studies have examined Pu interaction with clay minerals in sufficient detail to produce a credible mechanistic model of its behavior. In this work, Pu(IV) and Pu(V) interactions with silica, gibbsite (Aloxide), and Na-montmorillonite (smectite clay) were examined as a function of time and pH. Sorption of Pu(IV) and Pu(V) to gibbsite and silica increased with pH (4 to 10). The Pu(V) sorption edge shifted to lower pH values over time and approached that of Pu(IV). This behavior is apparently due to surface mediated reduction of Pu(V) to Pu(IV). Surface complexation constants describing Pu(IV)/Pu(V) sorption to aluminol and silanol groups were developed from the silica and gibbsite sorption experiments and applied to the montmorillonite dataset. The model provided an acceptable fit to the montmorillonite sorption data for Pu(V). In order to accurately predict Pu(IV) sorption to montmorillonite, the model required inclusion of ion exchange. The objective of this work is to measure the sorption of Pu(IV) and Pu(V) to silica, gibbsite, and smectite (montmorillonite). Aluminosilicate minerals are ubiquitous at the Nevada National Security Site and improving our understanding of Pu sorption to aluminosilicates (smectite clays in particular) is essential to the accurate prediction of Pu transport rates. These data will improve the mechanistic approach for modeling the hydrologic source term (HST) and provide sorption Kd parameters for use in CAU models. In both alluvium and tuff, aluminosilicates have been found to play a dominant role in the radionuclide retardation because their abundance is typically more than an order of magnitude greater than other potential sorbing minerals such as iron and manganese oxides (e.g. Vaniman et al., 1996). The sorption database used in recent HST models (Carle et al., 2006

  2. A Non-Electrostatic Surface Complexation Approach to Modeling Radionuclide Migration at the Nevada Test Site: II. Aluminosilicates

    Energy Technology Data Exchange (ETDEWEB)

    Zavarin, M; Bruton, C J

    2004-12-16

    Reliable quantitative prediction of contaminant transport in subsurface environments is critical to evaluating the risks associated with radionuclide migration. As part of the Underground Test Area (UGTA) program, radionuclide transport away from selected underground nuclear tests conducted in the saturated zone at the Nevada Test Site (NTS) is being examined. In the near-field environment, reactive transport simulations must account for changes in water chemistry and mineralogy as a function of time and their effect on radionuclide migration. Unlike the Kd approach, surface complexation reactions, in conjunction with ion exchange and precipitation, can be used to describe radionuclide reactive transport as a function of changing environmental conditions. They provide a more robust basis for describing radionuclide retardation in geochemically dynamic environments. In a companion report (Zavarin and Bruton, 2004), a database of radionuclide surface complexation reactions for calcite and iron oxide minerals was developed. In this report, a second set of reactions is developed: surface complexation (SC) and ion exchange (IE) to aluminosilicate minerals. The most simplified surface complexation model, the one-site non-electrostatic model (NEM), and the Vanselow IE model were used to fit a large number of published sorption data and a reaction constant database was developed. Surface complexation of Am(III), Eu(III), Np(V), Pu(IV), Pu(V), and U(VI) to aluminum oxide, silica, and aluminosilicate minerals was modeled using a generalized approach in which surface complexation to aluminosilicate >SiOH or >AlOH reactive sites was considered equivalent to the reactivity of aluminum oxide and silica reactive sites. Ion exchange was allowed to be mineral-dependent. The generalized NEM approach, in conjunction with Vanselow IE, was able to fit most published sorption data well. Fitting results indicate that surface complexation will dominate over ion exchange at pH >7 for the

  3. Non-electrostatic surface complexation models for protons and lead(II) sorption onto single minerals and their mixture.

    Science.gov (United States)

    Pagnanelli, Francesca; Bornoroni, Lorena; Moscardini, Emanuela; Toro, Luigi

    2006-05-01

    model taking into account both monodentate and bidentate complexes with the three active sites (additivity of lead binding). Experimental data of metal distribution in solid and liquid phases were successfully simulated by implementing the protonation and the surface complexation constants into the database of a dedicated software for chemical equilibria.

  4. A Non-Electrostatic Surface Complexation Approach to Modeling Radionuclide Migration at the Nevada Test Site: I. Iron Oxides and Calcite

    Energy Technology Data Exchange (ETDEWEB)

    Zavarin, M; Bruton, C J

    2004-12-17

    Reliable quantitative prediction of contaminant transport in subsurface environments is critical to evaluating the risks associated with radionuclide migration. As part of the Underground Test Area (UGTA) project, radionuclide transport away from various underground nuclear tests conducted in the saturated zone at the Nevada Test Site (NTS) is being examined. In the near-field environment, reactive transport simulations must account for changes in water chemistry and mineralogy as a function of time and their effect on radionuclide migration. Unlike the K{sub d} approach, surface complexation (SC) reactions, in conjunction with ion exchange and precipitation, can be used to describe radionuclide reactive transport as a function of changing environmental conditions. They provide a more robust basis for describing radionuclide retardation in geochemically dynamic environments. The interaction between several radionuclides considered relevant to the UGTA project and iron oxides and calcite are examined in this report. The interaction between these same radionuclides and aluminosilicate minerals is examined in a companion report (Zavarin and Bruton, 2004). Selection criteria for radionuclides were based on abundance, half-life, toxicity to human and environmental health, and potential mobility at NTS (Tompson et al., 1999). Both iron oxide and calcite minerals are known to be present at NTS in various locations and are likely to affect radionuclide migration from the near-field. Modeling the interaction between radionuclides and these minerals was based on surface complexation. The effectiveness of the most simplified SC model, the one-site Non-Electrostatic Model (NEM), to describe sorption under various solution conditions is evaluated in this report. NEM reactions were fit to radionuclide sorption data available in the literature, as well as sorption data recently collected for the UGTA project, and a NEM database was developed. For radionuclide-iron oxide sorption

  5. Electro-osmosis over inhomogeneously charged surfaces in presence of non-electrostatic ion-ion interactions

    Science.gov (United States)

    Ghosh, Uddipta; Chakraborty, Suman

    2016-06-01

    In this study, we attempt to bring out a generalized formulation for electro-osmotic flows over inhomogeneously charged surfaces in presence of non-electrostatic ion-ion interactions. To this end, we start with modified electro-chemical potential of the individual species and subsequently use it to derive modified Nernst-Planck equation accounting for the ionic fluxes generated because of the presence of non-electrostatic potential. We establish what we refer to as the Poisson-Helmholtz-Nernst-Planck equations, coupled with the Navier-Stokes equations, to describe the complete transport process. Our analysis shows that the presence of non-electrostatic interactions between the ions results in an excess body force on the fluid, and modifies the osmotic pressure as well, which has hitherto remained unexplored. We further apply our analysis to a simple geometry, in an effort to work out the Smoluchowski slip velocity for thin electrical double layer limits. To this end, we employ singular perturbation and develop a general framework for the asymptotic analysis. Our calculations reveal that the final expression for slip velocity remains the same as that without accounting for non-electrostatic interactions. However, the presence of non-electrostatic interactions along with ion specificity can significantly change the quantitative behavior of Smoluchowski slip velocity. We subsequently demonstrate that the presence of non-electrostatic interactions may significantly alter the effective interfacial potential, also termed as the "Zeta potential." Our analysis can potentially act as a guide towards the prediction and possibly quantitative determination of the implications associated with the existence of non-electrostatic potential, in an electrokinetic transport process.

  6. Solvation of complex surfaces via molecular density functional theory

    CERN Document Server

    Levesque, Maximilien; Rotenberg, Benjamin; Jeanmairet, Guillaume; Vuilleumier, Rodolphe; Borgis, Daniel

    2012-01-01

    We show that classical molecular density functional theory (MDFT), here in the homogeneous reference fluid approximation in which the functional is inferred from the properties of the bulk solvent, is a powerful new tool to study, at a fully molecular level, the solvation of complex surfaces and interfaces by polar solvents. This implicit solvent method allows for the determination of structural, orientational and energetic solvation properties that are on a par with all-atom molecular simulations performed for the same system, while reducing the computer time by two orders of magnitude. This is illustrated by the study of an atomistically-resolved clay surface composed of over a thousand atoms wetted by a molecular dipolar solvent. The high numerical efficiency of the method is exploited to carry a systematic analysis of the electrostatic and non-electrostatic components of the surface-solvent interaction within the popular CLAYFF force field. Solvent energetics and structure are found to depend weakly upon ...

  7. A non-electrostatic spacer for aerosol delivery

    DEFF Research Database (Denmark)

    Bisgaard, H; Anhøj, J; Klug, B;

    1995-01-01

    A pear shaped non-electrostatic spacer, composed of steel with a volume of 250 ml and equipped with a facemask containing integrated inlet and outlet valves for inspiration and expiration, was compared with three plastic spacers. The plastic spacers were primed with repeated puffs from a budesonide...... pressurised metered dose inhaler (p-MDI) to minimise the electrostatic charge on the plastic. The procedure prolonged the half life (t1/2) of the aerosol in the Nebuhaler from nine to 32 seconds. A normal cleaning procedure reduced the aerosol t1/2 back to baseline. The t1/2 of the aerosol in the metal spacer...... was 27 seconds and independent of the use of p-MDI. In vitro the maximum dose of budesonide from a p-MDI, expressed as a percentage of the nominal dose, was 56% from the non-electrostatic spacer, 61% from the Nebuhaler, 45% from the Babyhaler, and 30% from the AeroChamber. In 124 children, age 6 months...

  8. Predictive Surface Complexation Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Sverjensky, Dimitri A. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Earth and Planetary Sciences

    2016-11-29

    Surface complexation plays an important role in the equilibria and kinetics of processes controlling the compositions of soilwaters and groundwaters, the fate of contaminants in groundwaters, and the subsurface storage of CO2 and nuclear waste. Over the last several decades, many dozens of individual experimental studies have addressed aspects of surface complexation that have contributed to an increased understanding of its role in natural systems. However, there has been no previous attempt to develop a model of surface complexation that can be used to link all the experimental studies in order to place them on a predictive basis. Overall, my research has successfully integrated the results of the work of many experimentalists published over several decades. For the first time in studies of the geochemistry of the mineral-water interface, a practical predictive capability for modeling has become available. The predictive correlations developed in my research now enable extrapolations of experimental studies to provide estimates of surface chemistry for systems not yet studied experimentally and for natural and anthropogenically perturbed systems.

  9. Solvation of complex surfaces via molecular density functional theory.

    Science.gov (United States)

    Levesque, Maximilien; Marry, Virginie; Rotenberg, Benjamin; Jeanmairet, Guillaume; Vuilleumier, Rodolphe; Borgis, Daniel

    2012-12-14

    We show that classical molecular density functional theory, here in the homogeneous reference fluid approximation in which the functional is inferred from the properties of the bulk solvent, is a powerful new tool to study, at a fully molecular level, the solvation of complex surfaces and interfaces by polar solvents. This implicit solvent method allows for the determination of structural, orientational, and energetic solvation properties that are on a par with all-atom molecular simulations performed for the same system, while reducing the computer time by two orders of magnitude. This is illustrated by the study of an atomistically-resolved clay surface composed of over a thousand atoms wetted by a molecular dipolar solvent. The high numerical efficiency of the method is exploited to carry a systematic analysis of the electrostatic and non-electrostatic components of the surface-solvent interaction within the popular Clay Force Field (CLAYFF). Solvent energetics and structure are found to depend weakly upon the atomic charges distribution of the clay surface, even for a rather polar solvent. We conclude on the consequences of such findings for force-field development.

  10. Machining of Complex Sculptured Surfaces

    CERN Document Server

    2012-01-01

    The machining of complex sculptured surfaces is a global technological topic in modern manufacturing with relevance in both industrialized and emerging in countries particularly within the moulds and dies sector whose applications include highly technological industries such as the automotive and aircraft industry. Machining of Complex Sculptured Surfaces considers new approaches to the manufacture of moulds and dies within these industries. The traditional technology employed in the manufacture of moulds and dies combined conventional milling and electro-discharge machining (EDM) but this has been replaced with  high-speed milling (HSM) which has been applied in roughing, semi-finishing and finishing of moulds and dies with great success. Machining of Complex Sculptured Surfaces provides recent information on machining of complex sculptured surfaces including modern CAM systems and process planning for three and five axis machining as well as explanations of the advantages of HSM over traditional methods ra...

  11. The first step in layer-by-layer deposition: Electrostatics and/or non-electrostatics?

    NARCIS (Netherlands)

    Lyklema, J.; Deschênes, L.

    2011-01-01

    A critical discussion is presented on the properties and prerequisites of adsorbed polyelectrolytes that have to function as substrates for further layer-by-layer deposition. The central theme is discriminating between the roles of electrostatic and non-electrostatic interactions. In order to emphas

  12. Surface complexation model of uranyl sorption on Georgia kaolinite

    Science.gov (United States)

    Payne, T.E.; Davis, J.A.; Lumpkin, G.R.; Chisari, R.; Waite, T.D.

    2004-01-01

    The adsorption of uranyl on standard Georgia kaolinites (KGa-1 and KGa-1B) was studied as a function of pH (3-10), total U (1 and 10 ??mol/l), and mass loading of clay (4 and 40 g/l). The uptake of uranyl in air-equilibrated systems increased with pH and reached a maximum in the near-neutral pH range. At higher pH values, the sorption decreased due to the presence of aqueous uranyl carbonate complexes. One kaolinite sample was examined after the uranyl uptake experiments by transmission electron microscopy (TEM), using energy dispersive X-ray spectroscopy (EDS) to determine the U content. It was found that uranium was preferentially adsorbed by Ti-rich impurity phases (predominantly anatase), which are present in the kaolinite samples. Uranyl sorption on the Georgia kaolinites was simulated with U sorption reactions on both titanol and aluminol sites, using a simple non-electrostatic surface complexation model (SCM). The relative amounts of U-binding >TiOH and >AlOH sites were estimated from the TEM/EDS results. A ternary uranyl carbonate complex on the titanol site improved the fit to the experimental data in the higher pH range. The final model contained only three optimised log K values, and was able to simulate adsorption data across a wide range of experimental conditions. The >TiOH (anatase) sites appear to play an important role in retaining U at low uranyl concentrations. As kaolinite often contains trace TiO2, its presence may need to be taken into account when modelling the results of sorption experiments with radionuclides or trace metals on kaolinite. ?? 2004 Elsevier B.V. All rights reserved.

  13. Einstein Metrics on Complex Surfaces

    CERN Document Server

    Lebrun, C

    1995-01-01

    We consider compact complex surfaces with Hermitian metrics which are Einstein but not Kaehler. It is shown that the manifold must be CP2 blown up at 1,2, or 3 points, and the isometry group of the metric must contain a 2-torus. Thus the Page metric on CP2#(-CP2) is almost the only metric of this type.

  14. Surface complexation of heavy metal cations on clay edges: insights from first principles molecular dynamics simulation of Ni(II)

    Science.gov (United States)

    Zhang, Chi; Liu, Xiandong; Lu, Xiancai; He, Mengjia; Jan Meijer, Evert; Wang, Rucheng

    2017-04-01

    Aiming at an atomistic mechanism of heavy metal cation complexing on clay surfaces, we carried out systematic first principles molecular dynamics (FPMD) simulations to investigate the structures, free energies and acidity constants of Ni(II) complexes formed on edge surfaces of 2:1 phyllosilicates. Three representative complexes were studied, including monodentate complex on the tbnd SiO site, bidentate complex on the tbnd Al(OH)2 site, and tetradentate complex on the octahedral vacancy where Ni(II) fits well into the lattice. The complexes structures were characterized in detail. Computed free energy values indicate that the tetradentate complex is significantly more stable than the other two. The calculated acidity constants indicate that the tetradentate complex can get deprotonated (pKa = 8.4) at the ambient conditions whereas the other two hardly deprotonate due to extremely high pKa values. By comparing with the 2 Site Protolysis Non Electrostatic Surface Complexation and Cation Exchange (2SPNE SC/CE) model, the vacant site has been assigned to the strong site and the other two to the weak site, respectively. Thus a link has been built between atomistic simulations and macroscopic experiments and it is deduced that this should also apply to other heavy metal cations based on additional simulations of Co(II) and Cu(II) and previous simulations of Fe(II) and Cd(II)). This study forms a physical basis for understanding the transport and fixation of heavy metal elements in many geologic environments.

  15. Complex multiplication of abelian surfaces

    NARCIS (Netherlands)

    Streng, Theodorus Cornelis

    2010-01-01

    The theory of complex multiplication makes it possible to construct certain class fields and abelian varieties. The main theme of this thesis is making these constructions explicit for the case where the abelian varieties have dimension 2. Chapter I is an introduction to complex multiplication

  16. An index of floodplain surface complexity

    Science.gov (United States)

    Scown, Murray W.; Thoms, Martin C.; DeJager, Nathan R.

    2016-01-01

    Floodplain surface topography is an important component of floodplain ecosystems. It is the primary physical template upon which ecosystem processes are acted out, and complexity in this template can contribute to the high biodiversity and productivity of floodplain ecosystems. There has been a limited appreciation of floodplain surface complexity because of the traditional focus on temporal variability in floodplains as well as limitations to quantifying spatial complexity. An index of floodplain surface complexity (FSC) is developed in this paper and applied to eight floodplains from different geographic settings. The index is based on two key indicators of complexity, variability in surface geometry (VSG) and the spatial organisation of surface conditions (SPO), and was determined at three sampling scales. FSC, VSG, and SPO varied between the eight floodplains and these differences depended upon sampling scale. Relationships between these measures of spatial complexity and seven geomorphological and hydrological drivers were investigated. There was a significant decline in all complexity measures with increasing floodplain width, which was explained by either a power, logarithmic, or exponential function. There was an initial rapid decline in surface complexity as floodplain width increased from 1.5 to 5 km, followed by little change in floodplains wider than 10 km. VSG also increased significantly with increasing sediment yield. No significant relationships were determined between any of the four hydrological variables and floodplain surface complexity.

  17. Stable surface solitons in truncated complex potentials.

    Science.gov (United States)

    He, Yingji; Mihalache, Dumitru; Zhu, Xing; Guo, Lina; Kartashov, Yaroslav V

    2012-07-01

    We show that surface solitons in the one-dimensional nonlinear Schrödinger equation with truncated complex periodic potential can be stabilized by linear homogeneous losses, which are necessary to balance gain in the near-surface channel arising from the imaginary part of potential. Such solitons become stable attractors when the strength of homogeneous losses acquires values from a limited interval and they exist in focusing and defocusing media. The domains of stability of the surface solitons shrink with an increase in the amplitude of the imaginary part of complex potential.

  18. Stable surface solitons in truncated complex potentials

    CERN Document Server

    He, Yingji; Zhu, Xing; Guo, Lina; Kartashov, Yaroslav V

    2012-01-01

    We show that surface solitons in the one-dimensional nonlinear Schr\\"odinger equation with truncated complex periodic potential can be stabilized by linear homogeneous losses, which are necessary to balance gain in the near-surface channel arising from the imaginary part of potential. Such solitons become stable attractors when the strength of homogeneous losses acquires values from a limited interval and they exist in focusing and defocusing media. The domains of stability of surface solitons shrink with increase of the amplitude of imaginary part of complex potential.

  19. Research on ultrasonic detection of complex surfaces

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Parts of complex surface are widely used now in many fields, and their detection has caused much concern. In China many manufactories still carry on the traditional way of manual detection, which requires highly skilled personnel and efficiency is low. Some large manufactories have imported auto-detecting equipments, which require CAD data on the parts, or just divide the surface into several approximate planes for automatic detection. Phased-array system is seldom used, and the cost is high. Besides,most of the systems have not considered the automatic sensitivity compensation of parts with varying thickness. To improve the detection quality and efficiency of nondestructive test (NDT) of parts of complex surface, this paper puts forward an integrated ultrasonic NDT system characterized by: (1) Use of ultrasonic measurement and reverse of curved surface to solve the CAD data problem; (2) Use of an automatic sensitivity compensation algorithm (based on the part's modelling information obtained in surface reverse) to fit the variety of the thickness; (3) Use of template matching and pseudo-color imaging to improve the quality of detection results. The system features integration of low cost mature technologies, and is suitable for detection of various parts of different complex surfaces in medium-and-small enterprises. The test results showed that the system can automatically detect parts of complex surface successfully, and that the inspection result is good and reliable.

  20. COMPLEX SURFACE HARDENING OF STEEL ARTICLES

    Directory of Open Access Journals (Sweden)

    A. V. Kovalchuk

    2014-01-01

    Full Text Available The method of complex surface hardening of steel detailswas designed. The method is a compound of two processes of hardening: chemical heat treatment and physical vapor deposition (PVD of the coating. The result, achieved in this study is much higher, than in other work on this topic and is cumulative. The method designed can be used in mechanical engineering, medicine, energetics and is perspective for military and space technologies.

  1. Acid-base properties and surface complexation modeling of phosphate anion adsorption by wasted low grade iron ore with high phosphorus.

    Science.gov (United States)

    Yuan, Xiaoli; Bai, Chenguang; Xia, Wentang; An, Juan

    2014-08-15

    The adsorption phenomena and specific reaction processes of phosphate onto wasted low grade iron ore with high phosphorus (WLGIOWHP) were studied in this work. Zeta potential and Fourier transform infrared spectroscopy (FTIR) analyses were used to elucidate the interaction mechanism between WLGIOWHP and aqueous solution. The results implied that the main adsorption mechanism was the replacement of surface hydroxyl groups by phosphate via the formation of inner-sphere complex. The adsorption process was characterized by chemical adsorption onto WLGIOWHP. The non-electrostatic model (NEM) was used to simulate the surface adsorption of phosphate onto WLGIOWHP. The total surface site density and protonation constants for NEM (N(T)=1.6×10(-4) mol/g, K(a1)=2.2×10(-4), K(a2)=6.82×10(-9)) were obtained by non-linear data fitting of acid-base titrations. In addition, the NEM was used to establish the surface adsorption complexation modeling of phosphate onto WLGIOWHP. The model successfully predicted the adsorption of phosphate onto WLGIOWHP from municipal wastewater. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. Identification of complex molecules at surfaces

    Science.gov (United States)

    Green, F. M.; Dell, E. J.; Gilmore, I. S.; Seah, M. P.

    2008-04-01

    In this study, we develop a simple method using the SMILES molecular structure format to simulate fragmentation pathways in secondary ion mass spectrometry (SIMS). These pathways are found to have good agreement with fragmentation pathways identified using G-SIMS-FPM (Fragmentation Pathway Mapping) using the two examples of folic acid and Irganox 1010. G-SIMS is an easy-to-use method that considerably simplifies complex static SIMS spectra. G-SIMS-FPM allows the molecular structure to be re-assembled by following fragmentation pathways as the G-SIMS surface plasma temperature is varied. The simulated pathways help reduce the wide choice of possible structures faced by analysts as the molecular structure is reassembled, leading to more reliable molecular identification. A rapid method to establish a foundation database of simulated pathways using the community and a web-based system is proposed.

  3. A surface complexation and ion exchange model of Pb and Cd competitive sorption on natural soils

    Science.gov (United States)

    Serrano, Susana; O'Day, Peggy A.; Vlassopoulos, Dimitri; García-González, Maria Teresa; Garrido, Fernando

    2009-02-01

    The bioavailability and fate of heavy metals in the environment are often controlled by sorption reactions on the reactive surfaces of soil minerals. We have developed a non-electrostatic equilibrium model (NEM) with both surface complexation and ion exchange reactions to describe the sorption of Pb and Cd in single- and binary-metal systems over a range of pH and metal concentration. Mineralogical and exchange properties of three different acidic soils were used to constrain surface reactions in the model and to estimate surface densities for sorption sites, rather than treating them as adjustable parameters. Soil heterogeneity was modeled with >FeOH and >SOH functional groups, representing Fe- and Al-oxyhydroxide minerals and phyllosilicate clay mineral edge sites, and two ion exchange sites (X - and Y -), representing clay mineral exchange. An optimization process was carried out using the entire experimental sorption data set to determine the binding constants for Pb and Cd surface complexation and ion exchange reactions. Modeling results showed that the adsorption of Pb and Cd was distributed between ion exchange sites at low pH values and specific adsorption sites at higher pH values, mainly associated with >FeOH sites. Modeling results confirmed the greater tendency of Cd to be retained on exchange sites compared to Pb, which had a higher affinity than Cd for specific adsorption on >FeOH sites. Lead retention on >FeOH occurred at lower pH than for Cd, suggesting that Pb sorbs to surface hydroxyl groups at pH values at which Cd interacts only with exchange sites. The results from the binary system (both Pb and Cd present) showed that Cd retained in >FeOH sites decreased significantly in the presence of Pb, while the occupancy of Pb in these sites did not change in the presence of Cd. As a consequence of this competition, Cd was shifted to ion exchange sites, where it competes with Pb and possibly Ca (from the background electrolyte). Sorption on >SOH

  4. Marked fatgraph complexes and surface automorphisms

    DEFF Research Database (Denmark)

    Kuno, Yusuke; Penner, Robert; Turaev, Vladimir

    2013-01-01

    Combinatorial aspects of the Torelli-Johnson-Morita theory of surface automorphisms are extended to certain subgroups of the mapping class groups. These subgroups are defined relative to a specified homomorphism from the fundamental group of the surface onto an arbitrary group $K$. For $K$ abelia...

  5. Classification of flat slant surfaces in complex Euclidean plane

    OpenAIRE

    Chen, Bang-Yen

    2002-01-01

    It is well-known that the classification of flat surfaces in Euclidean 3space is one of the most basic results in differential geometry. For surfaces in the complex Euclidean plane $C^{2}$ endowed with almost complex structure $J$ , flat surfaces are the simplest ones from intrinsic point of views. On the other hand, from $J$ -action point of views, the most natural surfaces in $C^{2}$ are slant surfaces, i.e., surfaces with constant Wintinger angle. In this paper the author completely classi...

  6. Refined curve counting on complex surfaces

    OpenAIRE

    Göttsche, Lothar; Shende, Vivek

    2012-01-01

    We define refined invariants which "count" nodal curves in sufficiently ample linear systems on surfaces, conjecture that their generating function is multiplicative, and conjecture explicit formulas in the case of K3 and abelian surfaces. We also give a refinement of the Caporaso-Harris recursion, and conjecture that it produces the same invariants in the sufficiently ample setting. The refined recursion specializes at y = -1 to the Itenberg-Kharlamov-Shustin recursion for Welschinger invari...

  7. Surface nucleation in complex rheological systems

    Science.gov (United States)

    Herfurth, J.; Ulrich, J.

    2017-07-01

    Forced nucleation induced by suitable foreign seeds is an important tool to control the production of defined crystalline products. The quality of a surface provided by seed materials represents an important variable in the production of crystallizing layers that means for the nucleation process. Parameters like shape and surface structure, size and size distribution of the seed particles as well as the ability to hold up the moisture (the solvent), can have an influence on the nucleation process of different viscous supersaturated solutions. Here the properties of different starch powders as seeds obtained from corn, potato, rice, tapioca and wheat were tested. It could be found, that the best nucleation behavior of a sugar solution could be reached with the use of corn starch as seed material. Here the surface of the crystallized sugar layer is smooth, crystallization time is short (product is easily reproducible. Beneficial properties of seed materials are therefore an edged, uneven surface, small particle sizes as well as low moisture content at ambient conditions within the seed materials.

  8. New Route to Synthesize Surface Organometallic Complexes (SOMC): An Approach by Alkylating Halogenated Surface Organometallic Fragments

    KAUST Repository

    Hamieh, Ali Imad

    2017-02-01

    The aim of this thesis is to explore new simpler and efficient routes for the preparation of surface organometallic complexes (SOMC) for the transformation of small organic molecules to valuable products. The key element in this new route relies on surface alkylation of various halogenated surface coordination complexes or organometallic fragments (SOMF).

  9. Surface complexation of Pb(II) by hexagonal birnessite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, K.; Refson, K.; Sposito, G.

    2010-10-15

    Natural hexagonal birnessite is a poorly-crystalline layer type Mn(IV) oxide precipitated by bacteria and fungi which has a particularly high adsorption affinity for Pb(II). X-ray spectroscopic studies have shown that Pb(II) forms strong inner-sphere surface complexes mainly at two sites on hexagonal birnessite nanoparticles: triple corner-sharing (TCS) complexes on Mn(IV) vacancies in the interlayers and double edge-sharing (DES) complexes on lateral edge surfaces. Although the TCS surface complex has been well characterized by spectroscopy, some important questions remain about the structure and stability of the complexes occurring on the edge surfaces. First-principles simulation techniques such as density functional theory (DFT) offer a useful way to address these questions by providing complementary information that is difficult to obtain by spectroscopy. Following this computational approach, we used spin-polarized DFT to perform total-energy-minimization geometry optimizations of several possible Pb(II) surface complexes on model birnessite nanoparticles similar to those that have been studied experimentally. We first validated our DFT calculations by geometry optimizations of (1) the Pb-Mn oxyhydroxide mineral, quenselite (PbMnO{sub 2}OH), and (2) the TCS surface complex, finding good agreement with experimental structural data while uncovering new information about bonding and stability. Our geometry optimizations of several protonated variants of the DES surface complex led us to conclude that the observed edge-surface species is very likely to be this complex if the singly-coordinated terminal O that binds to Pb(II) is protonated. Our geometry optimizations also revealed that an unhydrated double corner-sharing (DCS) species that has been proposed as an alternative to the DES complex is intrinsically unstable on nanoparticle edge surfaces, but could become stabilized if the local coordination environment is well-hydrated. A significant similarity exists

  10. Complex land surface phenologies of moisture status

    Science.gov (United States)

    Henebry, G. M.; Doubkova, M.

    2006-12-01

    Making cross-scale linkages from experimental plots or flux tower footprints to regional and continental extents is made difficult by disparate spatial and temporal scales between process and observation. While exchanges between the vegetated land surface and the atmospheric boundary layer are continual, sampling and observations are typically intermittent in time and limited across space. Remote sensing of reflected sunlight has proven useful to track ecological dynamics. These observations are, however, restricted to daytime and often obscured by cloud cover, necessitating production of multi-date composites. The current generation of passive microwave radiometers can observe the land surface both day and night regardless of cloudiness, albeit at a spatial resolution coarser than typically used in ecological remote sensing. Datastreams from the AMSR-E (Advanced Microwave Scanning Radiometer-EOS) onboard NASA's Aqua platform are processed daily at the National Snow and Ice Data Center (NSIDC) into various products, including global retrievals of surficial soil moisture and vegetation water content based on microwave brightness temperatures observed at multiple frequencies. Due to sensor orbit and swath width, gaps occur at the lower latitudes in daily products. We have further processed the product-streams from the descending (01:30) and ascending (13:30) orbits into separate smoothed daily composites using an 8-day retrospective moving average. Of particular interest for synoptic ecology is the diel difference in vegetation water content. When the difference between the pre-dawn and the early afternoon values is positive, it suggests that the supply of moisture from the root zone is not able to keep pace with evapotranspiration during the day, but the soil and canopy moisture equalize overnight. Time series of the diel difference show rapid changes in moisture status in response to precipitation events and dry spells. What constitutes the appropriate baseline

  11. A surface complexation model of YREE sorption on Ulva lactuca in 0.05-5.0 M NaCl solutions

    Science.gov (United States)

    Zoll, Alison M.; Schijf, Johan

    2012-11-01

    We present distribution coefficients, log iKS, for the sorption of yttrium and the rare earth elements (YREEs) on BCR-279, a dehydrated tissue homogenate of a marine macroalga, Ulva lactuca, resembling materials featured in chemical engineering studies aimed at designing renewable biosorbents. Sorption experiments were conducted in NaCl solutions of different ionic strength (0.05, 0.5, and 5.0 M) at T = 25 °C over the pH range 2.7-8.5. Distribution coefficients based on separation of the dissolved and particulate phase by conventional filtration (3 kDa) using an existing pH-dependent model. Colloid-corrected values were renormalized to free-cation concentrations by accounting for YREE hydrolysis and chloride complexation. At each ionic strength, the pH dependence of the renormalized values is accurately described with a non-electrostatic surface complexation model (SCM) that incorporates YREE binding to three monoprotic functional groups, previously characterized by alkalimetric titration, as well as binding of YREE-hydroxide complexes (MOH2+) to the least acidic one (pKa ∼ 9.5). In non-linear regressions of the distribution coefficients as a function of pH, each pKa was fixed at its reported value, while stability constants of the four YREE surface complexes were used as adjustable parameters. Data for a single fresh U. lactuca specimen in 0.5 M NaCl show generally the same pH-dependent behavior but a lower degree of sorption and were excluded from the regressions. Good linear free-energy relations (LFERs) between stability constants of the YREE-acetate and YREE-hydroxide solution complex and surface complexes with the first and third functional group, respectively, support their prior tentative identifications as carboxyl and phenol. A similar confirmation for the second group is precluded by insufficient knowledge of the stability of YREE-phosphate complexes and a perceived lack of YREE binding in 0.05 M NaCl; this issue awaits further study. The results

  12. Molecularly imprinted Ru complex catalysts integrated on oxide surfaces.

    Science.gov (United States)

    Muratsugu, Satoshi; Tada, Mizuki

    2013-02-19

    Selective catalysis is critical for the development of green chemical processes, and natural enzymes that possess specialized three-dimensional reaction pockets with catalytically active sites represent the most sophisticated systems for selective catalysis. A reaction space in an enzyme consists of an active metal center, functional groups for molecular recognition (such as amino acids), and a surrounding protein matrix to prepare the reaction pocket. The artificial design of such an integrated catalytic unit in a non-enzymatic system remains challenging. Molecular imprinting of a supported metal complex provides a promising approach for shape-selective catalysis. In this process, an imprinted cavity with a shape matched to a template molecule is created in a polymer matrix with a catalytically active metal site. In this Account, we review our studies on molecularly imprinted metal complex catalysts, focusing on Ru complexes, on oxide surfaces for shape-selective catalysis. Oxide surface-attached transition metal complex catalysts not only improve thermal stability and catalyst dispersion but also provide unique catalytic performance not observed in homogeneous precursors. We designed molecularly imprinted Ru complexes by using surface-attached Ru complexes with template ligands and inorganic/organic surface matrix overlayers to control the chemical environment around the active metal complex catalysts on oxide surfaces. We prepared the designed, molecularly imprinted Ru complexes on SiO(2) surfaces in a step-by-step manner and characterized them with solid-state (SS) NMR, diffuse-reflectance (DR) UV-vis, X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller isotherm (BET), X-ray fluorescence (XRF), and Ru K-edge extended X-ray absorption fine structure (EXAFS). The catalytic performances of these Ru complexes suggest that this process of molecular imprinting facilitates the artificial integration of catalytic functions at surfaces. Further advances such

  13. Research on Ultrasonic NDT System for Complex Surface Parts

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Aimed at inner quality controlling for complex surface parts, an ultrasonic testing system for complex surface parts has been developed using ultrasonic NDT(Non-destructive Testing)which has features of strong penetration, well direction, high sensitivity, low cost, and harmless to people and material. The technologies of the computer, NC (Numerical control), precision mechanism, signal analysis and processing were integrated in the testing system. The system includes a PC, system software, ultrasonic data ...

  14. Research on Complexity of Surface Undulating Shapes of Rock Joints

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    The surface undulating shapes of rock joints have been described qualitatively or experimental-quantitatively for a long time. The non-determined describing method can not fit quantitative evaluation of mechanical parameters of rock joints in engineering. In this paper, relative amplitude (RA) is chosen as a quantitative-describing index of surface measurement of 1 023 surface undulating curves which conducted by profile curve device(PCD). We discuss the nonuniformity,anisotropy and unhomogeneity of surface undulating shapes of joints. A new method that analyzes the complexity of surface undulating shapes of rock joints directional-statistically in various rock joints is also put forward.

  15. Decomposition and reconstitution principle for complex surfaces and its applications

    Institute of Scientific and Technical Information of China (English)

    黄克正; 艾兴; 张承瑞

    1997-01-01

    Though there are already a variety of models for complex surfaces, they are not so convenient as needed in practice. A hierarchical model and the principle of decomposition and reconstitution for complex surfaces have been proposed, which have the potential to enhance the support of automated design systems on creative work intelligently Then the progress made is discussed involving the applications of the new principle in the following three areas:conjugation surface calculation, tool path generation in numerically controlled machining, and machining process innovation by re-recognition

  16. Surface complexation modeling of inositol hexaphosphate sorption onto gibbsite.

    Science.gov (United States)

    Ruyter-Hooley, Maika; Larsson, Anna-Carin; Johnson, Bruce B; Antzutkin, Oleg N; Angove, Michael J

    2015-02-15

    The sorption of Inositol hexaphosphate (IP6) onto gibbsite was investigated using a combination of adsorption experiments, (31)P solid-state MAS NMR spectroscopy, and surface complexation modeling. Adsorption experiments conducted at four temperatures showed that IP6 sorption decreased with increasing pH. At pH 6, IP6 sorption increased with increasing temperature, while at pH 10 sorption decreased as the temperature was raised. (31)P MAS NMR measurements at pH 3, 6, 9 and 11 produced spectra with broad resonance lines that could be de-convoluted with up to five resonances (+5, 0, -6, -13 and -21ppm). The chemical shifts suggest the sorption process involves a combination of both outer- and inner-sphere complexation and surface precipitation. Relative intensities of the observed resonances indicate that outer-sphere complexation is important in the sorption process at higher pH, while inner-sphere complexation and surface precipitation are dominant at lower pH. Using the adsorption and (31)P MAS NMR data, IP6 sorption to gibbsite was modeled with an extended constant capacitance model (ECCM). The adsorption reactions that best described the sorption of IP6 to gibbsite included two inner-sphere surface complexes and one outer-sphere complex: ≡AlOH + IP₆¹²⁻ + 5H⁺ ↔ ≡Al(IP₆H₄)⁷⁻ + H₂O, ≡3AlOH + IP₆¹²⁻ + 6H⁺ ↔ ≡Al₃(IP₆H₃)⁶⁻ + 3H₂O, ≡2AlOH + IP₆¹²⁻ + 4H⁺ ↔ (≡AlOH₂)₂²⁺(IP₆H₂)¹⁰⁻. The inner-sphere complex involving three surface sites may be considered to be equivalent to a surface precipitate. Thermodynamic parameters were obtained from equilibrium constants derived from surface complexation modeling. Enthalpies for the formation of inner-sphere surface complexes were endothermic, while the enthalpy for the outer-sphere complex was exothermic. The entropies for the proposed sorption reactions were large and positive suggesting that changes in solvation of species play a major role in driving

  17. New polypyridine anchoring ligands for coordination complexes and surface functionalization

    OpenAIRE

    Müller, Steffen

    2015-01-01

    This PhD thesis focuses on the synthesis of new polypyridine anchoring ligands and several dfferent applications. The ligands consist of a coordinating part, a flexible linker and an anchoring group. Due to the fact that different anchoring groups were used, the ligands can be applied for several types of surface-materials. Using these anchoring ligands, several coordination complexes were synthesized. Ruthenium-based complexes, bearing an ion-sensitive ligand, were tested towards...

  18. Alpha surfaces for complex space-times with torsion

    CERN Document Server

    Esposito, G

    1993-01-01

    This paper studies necessary conditions for the existence of alpha-surfaces in complex space-time manifolds with nonvanishing torsion. For these manifolds, Lie brackets of vector fields and spinor Ricci identities contain explicitly the effects of torsion. This leads to an integrability condition for alpha-surfaces which does not involve just the self-dual Weyl spinor, as in complex general relativity, but also the torsion spinor, in a nonlinear way, and its covariant derivative. Interestingly, a particular solution of the integrability condition is given by conformally right-flat and right-torsion-free space-times.

  19. Surfaces with parallel mean curvature vector in complex space forms

    CERN Document Server

    Fetcu, Dorel

    2010-01-01

    We consider a quadratic form defined on the surfaces with parallel mean curvature vector of an any dimensional complex space form and prove that its $(2,0)$-part is holomorphic. When the complex dimension of the ambient space is equal to $2$ we define a second quadratic form with the same property and then determine those surfaces with parallel mean curvature vector on which the $(2,0)$-parts of both of them vanish. We also provide a reduction of codimension theorem and prove a non-existence result for $2$-spheres with parallel mean curvature vector.

  20. Surface complexation modeling of americium sorption onto volcanic tuff.

    Science.gov (United States)

    Ding, M; Kelkar, S; Meijer, A

    2014-10-01

    Results of a surface complexation model (SCM) for americium sorption on volcanic rocks (devitrified and zeolitic tuff) are presented. The model was developed using PHREEQC and based on laboratory data for americium sorption on quartz. Available data for sorption of americium on quartz as a function of pH in dilute groundwater can be modeled with two surface reactions involving an americium sulfate and an americium carbonate complex. It was assumed in applying the model to volcanic rocks from Yucca Mountain, that the surface properties of volcanic rocks can be represented by a quartz surface. Using groundwaters compositionally representative of Yucca Mountain, americium sorption distribution coefficient (Kd, L/Kg) values were calculated as function of pH. These Kd values are close to the experimentally determined Kd values for americium sorption on volcanic rocks, decreasing with increasing pH in the pH range from 7 to 9. The surface complexation constants, derived in this study, allow prediction of sorption of americium in a natural complex system, taking into account the inherent uncertainty associated with geochemical conditions that occur along transport pathways.

  1. Deduction of static surface roughness from complex excess attenuation.

    Science.gov (United States)

    Nichols, Andrew; Attenborough, Keith; Taherzadeh, Shahram

    2011-03-01

    Data for complex excess attenuation have been used to determine the effective surface admittance and hence characteristic roughness size of a surface comprising a random distribution of semi-cylindrical rods on an acoustically hard plane. The inversion for roughness size is based on a simplified boss model. The technique is shown to be effective to within 4%, up to a threshold roughness packing density of 32%, above which the interaction between scattering elements appears to exceed that allowed by the model.

  2. Conformal nanopatterning of extracellular matrix proteins onto topographically complex surfaces.

    Science.gov (United States)

    Sun, Yan; Jallerat, Quentin; Szymanski, John M; Feinberg, Adam W

    2015-02-01

    Our Patterning on Topography (PoT) printing technique enables fibronectin, laminin and other proteins to be applied to biomaterial surfaces in complex geometries that are inaccessible using traditional soft lithography techniques. Engineering combinatorial surfaces that integrate topographical and biochemical micropatterns enhances control of the biotic-abiotic interface. Here, we used this method to understand cardiomyocyte response to competing physical and chemical cues in the microenvironment.

  3. Classification of Flat Lagrangian Surfaces in Complex Lorentzian Plane

    Institute of Scientific and Technical Information of China (English)

    Bang-Yen CHEN; Johan FASTENAKELS

    2007-01-01

    One of the most fundamental problems in the study of Lagrangian submanifolds fromRiemannian geometric point of view is to classify Lagrangian immersions of real space forms intocomplex space forms. The main purpose of this paper is thus to classify flat Lagrangian surfaces inthe Lorentzian complex plane C12. Our main result states that there are thirty-eight families of flatLagrangian surfaces in C12. Conversely, every flat Lagrangian surface in C12 is locally congruent to oneof the thirty-eight families.

  4. Computational molecular basis for improved silica surface complexation models

    Energy Technology Data Exchange (ETDEWEB)

    Sahai, Nita; Rosso, Kevin M.

    2006-06-06

    The acidity and reactivity of surface sites on amorphous and crystalline polymorphs of silica and other oxides control their thermodynamic stability and kinetic reactivity towards reactants in surface-controlled processes of environmental, industrial, biomedical and technological relevance. Recent advances in computational methodologies such as CPMD and increasing computer power combined with spectroscopic measurements are now making it possible to link, with an impressive degree of accuracy, the molecular-level description of these processes to phenomenological, surface complexation models The future challenge now lies in linking mesoscale properties at the nanometer scale to phenomenological models that will afford a more intuitive understanding of the systems under consideration.

  5. Tailoring optical complex fields with nano-metallic surfaces

    Directory of Open Access Journals (Sweden)

    Rui Guanghao

    2015-04-01

    Full Text Available Recently there is an increasing interest in complex optical fields with spatially inhomogeneous state of polarizations and optical singularities. Novel effects and phenomena have been predicted and observed for light beams with these unconventional states. Nanostructured metallic thin film offers unique opportunities to generate, manipulate and detect these novel fields. Strong interactions between nano-metallic surfaces and complex optical fields enable the development of highly compact and versatile functional devices and systems. In this review, we first briefly summarize the recent developments in complex optical fields. Various nano-metallic surface designs that can produce and manipulate complex optical fields with tailored characteristics in the optical far field will be presented. Nano-metallic surfaces are also proven to be very effective for receiving and detection of complex optical fields in the near field. Advances made in this nascent field may enable the design of novel photonic devices and systems for a variety of applications such as quantum optical information processing and integrated photonic circuits.

  6. Alkali-crown ether complexes at metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Thontasen, Nicha; Deng, Zhitao; Rauschenbach, Stephan [Max Planck Institute for Solid State Research, Stuttgart (Germany); Levita, Giacomo [University of Trieste, Trieste (Italy); Malinowski, Nikola [Max Planck Institute for Solid State Research, Stuttgart (Germany); Bulgarian Academy of Sciences, Sofia (Bulgaria); Kern, Klaus [Max Planck Institute for Solid State Research, Stuttgart (Germany); EPFL, Lausanne (Switzerland)

    2010-07-01

    Crown ethers are polycyclic ethers which, in solution, selectively bind cations depending on the size of the ring cavity. The study of a single host-guest complex is highly desirable in order to reveal the characteristics of these specific interactions at the atomic scale. Such detailed investigation is possible at the surface where high resolution imaging tools like scanning tunneling microscopy (STM) can be applied. Here, electrospray ion beam deposition (ES-IBD) is employed for the deposition of Dibenzo-24-crown-8 (DB24C8)-H{sup +}, -Na{sup +} and -Cs{sup +} complexes on a solid surface in ultrahigh vacuum (UHV). Where other deposition techniques have not been successful, this deposition technique combines the advantages of solution based preparation of the complex ions with a highly clean and controlled deposition in UHV. Single molecular structures and the cation-binding of DB24C8 at the surface are studied in situ by STM and MALDI-MS (matrix assisted laser desorption ionization mass spectrometry). The internal structure of the complex, i.e. ring and cavity, is observable only when alkali cations are incorporated. The BD24C8-H{sup +} complex in contrast appears as a compact feature. This result is in good agreement with theoretical models based on density functional theory calculations.

  7. Simultaneous application of dissolution/precipitation and surface complexation/surface precipitation modeling to contaminant leaching

    NARCIS (Netherlands)

    Apul, D.S.; Gardner, K.H.; Eighmy, T.T.; Fallman, A.M.; Comans, R.N.J.

    2005-01-01

    This paper discusses the modeling of anion and cation leaching from complex matrixes such as weathered steel slag. The novelty of the method is its simultaneous application of the theoretical models for solubility, competitive sorption, and surface precipitation phenomena to a complex system. Select

  8. Surface active complexes formed between keratin polypeptides and ionic surfactants.

    Science.gov (United States)

    Pan, Fang; Lu, Zhiming; Tucker, Ian; Hosking, Sarah; Petkov, Jordan; Lu, Jian R

    2016-12-15

    Keratins are a group of important proteins in skin and hair and as biomaterials they can provide desirable properties such as strength, biocompatibility, and moisture regaining and retaining. The aim of this work is to develop water-soluble keratin polypeptides from sheep wool and then explore how their surface adsorption behaves with and without surfactants. Successful preparation of keratin samples was demonstrated by identification of the key components from gel electrophoresis and the reproducible production of gram scale samples with and without SDS (sodium dodecylsulphate) during wool fibre dissolution. SDS micelles could reduce the formation of disulphide bonds between keratins during extraction, reducing inter-molecular crosslinking and improving keratin polypeptide solubility. However, Zeta potential measurements of the two polypeptide batches demonstrated almost identical pH dependent surface charge distributions with isoelectric points around pH 3.5, showing complete removal of SDS during purification by dialysis. In spite of different solubility from the two batches of keratin samples prepared, very similar adsorption and aggregation behavior was revealed from surface tension measurements and dynamic light scattering. Mixing of keratin polypeptides with SDS and C12TAB (dodecyltrimethylammonium bromide) led to the formation of keratin-surfactant complexes that were substantially more effective at reducing surface tension than the polypeptides alone, showing great promise in the delivery of keratin polypeptides via the surface active complexes. Neutron reflection measurements revealed the coexistence of surfactant and keratin polypeptides at the interface, thus providing the structural support to the observed surface tension changes associated with the formation of the surface active complexes.

  9. Mars - A planet with a complex surface evolution

    Science.gov (United States)

    Arvidson, R. E.; Coradini, M.

    1975-01-01

    The surface of Mars has evolved to its present form through a complex sequence of tectonism and associated volcanism, impact processes, water erosion, mass movements, and wind action. The diversity of geological processes active in past Martian history far exceeded most predictions. By the same token, predictions of processes modifying the satellites of the outer planets may fall far short of the true range of phenomena. A summary of present though with regard to Martian surface evolution is presented to serve as a case in point of the value of imagery and topography data in making interpretations of geological histories.

  10. Exploring complex networks via topological embedding on surfaces.

    Science.gov (United States)

    Aste, Tomaso; Gramatica, Ruggero; Di Matteo, T

    2012-09-01

    We demonstrate that graphs embedded on surfaces are a powerful and practical tool to generate, to characterize, and to simulate networks with a broad range of properties. Any network can be embedded on a surface with sufficiently high genus and therefore the study of topologically embedded graphs is non-restrictive. We show that the local properties of the network are affected by the surface genus which determines the average degree, which influences the degree distribution, and which controls the clustering coefficient. The global properties of the graph are also strongly affected by the surface genus which is constraining the degree of interwovenness, changing the scaling properties of the network from large-world kind (small genus) to small- and ultrasmall-world kind (large genus). Two elementary moves allow the exploration of all networks embeddable on a given surface and naturally introduce a tool to develop a statistical mechanics description for these networks. Within such a framework, we study the properties of topologically embedded graphs which dynamically tend to lower their energy towards a ground state with a given reference degree distribution. We show that the cooling dynamics between high and low "temperatures" is strongly affected by the surface genus with the manifestation of a glass-like transition occurring when the distance from the reference distribution is low. We prove, with examples, that topologically embedded graphs can be built in a way to contain arbitrary complex networks as subgraphs. This method opens a new avenue to build geometrically embedded networks on hyperbolic manifolds.

  11. Surface Complexation Modelling in Metal-Mineral-Bacteria Systems

    Science.gov (United States)

    Johnson, K. J.; Fein, J. B.

    2002-12-01

    The reactive surfaces of bacteria and minerals can determine the fate, transport, and bioavailability of aqueous heavy metal cations. Geochemical models are instrumental in accurately accounting for the partitioning of the metals between mineral surfaces and bacteria cell walls. Previous research has shown that surface complexation modelling (SCM) is accurate in two-component systems (metal:mineral and metal:bacteria); however, the ability of SCMs to account for metal distribution in mixed metal-mineral-bacteria systems has not been tested. In this study, we measure aqueous Cd distributions in water-bacteria-mineral systems, and compare these observations with predicted distributions based on a surface complexation modelling approach. We measured Cd adsorption in 2- and 3-component batch adsorption experiments. In the 2-component experiments, we measured the extent of adsorption of 10 ppm aqueous Cd onto either a bacterial or hydrous ferric oxide sorbent. The metal:bacteria experiments contained 1 g/L (wet wt.) of B. subtilis, and were conducted as a function of pH; the metal:mineral experiments were conducted as a function of both pH and HFO content. Two types of 3-component Cd adsorption experiments were also conducted in which both mineral powder and bacteria were present as sorbents: 1) one in which the HFO was physically but not chemically isolated from the system using sealed dialysis tubing, and 2) others where the HFO, Cd and B. subtilis were all in physical contact. The dialysis tubing approach enabled the direct determination of the concentration of Cd on each sorbing surface, after separation and acidification of each sorbent. The experiments indicate that both bacteria and mineral surfaces can dominate adsorption in the system, depending on pH and bacteria:mineral ratio. The stability constants, determined using the data from the 2-component systems, along with those for other surface and aqueous species in the systems, were used with FITEQL to

  12. Automatic extraction of complex surface models from range images using a trimmed-rational Bezier surface

    Science.gov (United States)

    Boulanger, Pierre; Sekita, Iwao

    1993-08-01

    This paper presents a new method for the extraction of a rational Bezier surface from a set of data points. The algorithm is divided into four parts. First, a least median square fitting algorithm is used to extract a Bezier surface from the data set. Second, from this initial surface model an analysis of the data set is performed to eliminate outliers. Third, the algorithm then improves the fit over the residual points by modifying the weights of a rational Bezier surface using a non-linear optimization method. A further improvement of the fit is achieved using a new intrinsic parameterization technique. Fourth, an approximation of the region boundary is performed using a NURB with knots. Experimental results show that the current algorithm is robust and can precisely approximate complex surfaces.

  13. Complex inductance, excess noise, and surface magnetism in dc SQUIDs.

    Science.gov (United States)

    Sendelbach, S; Hover, D; Mück, M; McDermott, R

    2009-09-11

    We have characterized the complex inductance of dc SQUIDs cooled to millikelvin temperatures. The SQUID inductance displays a rich, history-dependent structure as a function of temperature, with fluctuations of order 1 fH. At a fixed temperature, the SQUID inductance fluctuates with a 1/f power spectrum; the inductance noise is highly correlated with the conventional 1/f flux noise. The data are interpreted in terms of the reconfiguration of clusters of surface spins, with correlated fluctuations of effective magnetic moments and relaxation times.

  14. Zinc surface complexes on birnessite: A density functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Kideok D.; Refson, Keith; Sposito, Garrison

    2009-01-05

    Biogeochemical cycling of zinc is strongly influenced by sorption on birnessite minerals (layer-type MnO2), which are found in diverse terrestrial and aquatic environments. Zinc has been observed to form both tetrahedral (Zn{sup IV}) and octahedral (Zn{sup VI}) triple-corner-sharing surface complexes (TCS) at Mn(IV) vacancy sites in hexagonal birnessite. The octahedral complex is expected to be similar to that of Zn in the Mn oxide mineral, chalcophanite (ZnMn{sub 3}O{sub 7} {center_dot} 3H{sub 2}O), but the reason for the occurrence of the four-coordinate Zn surface species remains unclear. We address this issue computationally using spin-polarized Density Functional Theory (DFT) to examine the Zn{sub IV}-TCS and Zn{sup VI}-TCS species. Structural parameters obtained by DFT geometry optimization were in excellent agreement with available experimental data on Zn-birnessites. Total energy, magnetic moments, and electron-overlap populations obtained by DFT for isolated Zn{sup IV}-TCS revealed that this species is stable in birnessite without a need for Mn(III) substitution in the octahedral sheet and that it is more effective in reducing undersaturation of surface O at a Mn vacancy than is Zn{sub VI}-TCS. Comparison between geometry-optimized ZnMn{sub 3}O{sub 7} {center_dot} 3H{sub 2}O (chalcophanite) and the hypothetical monohydrate mineral, ZnMn{sub 3}O{sub 7} {center_dot} H{sub 2}O, which contains only tetrahedral Zn, showed that the hydration state of Zn significantly affects birnessite structural stability. Finally, our study also revealed that, relative to their positions in an ideal vacancy-free MnO{sub 2}, Mn nearest to Zn in a TCS surface complex move toward the vacancy by 0.08-0.11 {angstrom}, while surface O bordering the vacancy move away from it by 0.16-0.21 {angstrom}, in agreement with recent X-ray absorption spectroscopic analyses.

  15. Molecular assembly and organic film growth on complex intermetallic surfaces

    Science.gov (United States)

    Al-Mahboob, Abdullah; Sharma, Hem Raj; Sadowski, Jerzy T.; Ledieu, Julian; Fournée, Vincent; McGrath, Ronan

    We extensively studied the role of molecular symmetry and symmetry/structures of wide ranges of substrate-surfaces from non-periodic to periodic to quasi-crystalline in nucleation, growth and phase transition in films made of organic molecular materials. Recently, most interest in quasicrystals is due to the generalization of aperiodic ordering to several classes of systems. Compared to periodic materials, these provide a closer approximation to an isotropic first Brillouin zone, which is of great importance to the design of new functional materials. Here, we present results obtained from our ongoing study of interface mediated molecular assembly extended on complex intermetallic surfaces with specific examples of C60 and Zn-phthalocyanine on quasicrystalline and approximant surfaces. We employed in-situ real-time low-energy electron microscopy (LEEM) for investigation of the processes in assembly and film growth and post-growth STM study and DFT calculations to understand structural details and growth mechanism. Research were carried out in part at the Center for Functional Nanomaterials, Brookhaven National Lab, USA; partly at Institut Jean Lamour, Université de Lorraine, France; and partly at the Surface Science Research Centre, University of Liverpool, UK.

  16. Uranium(VI) sorption onto magnetite. Increasing confidence in surface complexation models using chemically evident surface chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Bok, Frank [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes

    2017-06-01

    Surface complexation models have made great efforts in describing the sorption of various radionuclides on naturally occurring mineral phases. Unfortunately, many of the published sorption parameter sets are built upon unrealistic or even wrong surface chemistry. This work describes the benefit of combining spectroscopic and batch sorption experimental data to create a reliable and consistent surface complexation parameter set.

  17. Reliability of surface EMG measurements from the suprahyoid muscle complex

    DEFF Research Database (Denmark)

    Kothari, Mohit; Stubbs, Peter William; Pedersen, Asger Roer

    2017-01-01

    reliable for ≈50% of participants. Although using sEMG to assess swallowing musculature function is easier to perform clinically and more comfortable to patients than invasive measures, as the measurement of muscle activity using TMS is unreliable, the use of sEMG for this muscle group is not recommended......Background: Assessment of swallowing musculature using motor evoked potentials (MEPs) can be used to evaluate neural pathways. However, recording of the swallowing musculature is often invasive, uncomfortable and unrealistic in normal clinical practise. Objective: To investigate the possibility...... of using the suprahyoid muscle complex (SMC) using surface electromyography (sEMG) to assess changes to neural pathways by determining the reliability of measurements in healthy participants over days. Methods: Seventeen healthy participants were recruited. Measurements were performed twice with one week...

  18. Ternary Complexation on Bacterial Surfaces: Implications for Subsurface Anion Transport

    Science.gov (United States)

    Maclean, L. C.; Higginbottom, C. M.; Fowle, D. A.

    2002-12-01

    The physical, chemical, and biological controls on contaminant mobilities in aquatic ecosystems must be determined to establish the threat that contamination poses to the environment. Quantitative models of contaminant mobilities are required as a prerequisite to guide remediation efforts and to prioritize the potential hazard to the ecosystem of each contaminated site. It is well established that mineral surface adsorption is an important control on contaminant mobilities, and many studies have utilized thermodynamics to quantify metal/organic adsorption in order to yield predictive models of contaminant transport. However, these models of contaminant transport may not be representative of the reactions which control contaminant mobilities as most mineral surfaces are coated with organic acids, bacteria, and extracellular polymers. Numerous laboratory studies have demonstrated that bacterial cell walls have a high affinity for binding metal cations, and field studies indicate that a significant proportion of bacteria cells and associated extracellular matrices are coated with small scale hydrous metal oxides. The small size of bacteria, and in many cases the nanoscale of their associated mineral phases, suggests these bacteria-mineral composites may represent a large proportion of surface area exposed to fluid flow. Therefore, due to the affinity of bacterial cell walls for cations and biominerals, bacteria may also have a significant impact on anionic contaminant mobility in many natural systems. The extent of metal-bacteria adsorption reactions varies drastically as a function of pH and solution chemistry. Current adsorption models have focused on the interactions of positively charged metal cations with bacterial surfaces, however in many oxidizing environments metals such as Cr exist as anions or anionic complexes. We have studied the ability of non-metabolizing cells of the bacterial species Bacillus subtilis and Shewanella putrifaciens to adsorb aqueous Cr

  19. Reliability of surface electromyography measurements from the suprahyoid muscle complex.

    Science.gov (United States)

    Kothari, M; Stubbs, P W; Pedersen, A R; Jensen, J; Nielsen, J F

    2017-09-01

    Assessment of swallowing musculature using motor evoked potentials (MEPs) can be used to evaluate neural pathways. However, recording of the swallowing musculature is often invasive, uncomfortable and unrealistic in normal clinical practice. To investigate the possibility of using the suprahyoid muscle complex (SMC) using surface electromyography (sEMG) to assess changes to neural pathways by determining the reliability of measurements in healthy participants over days. Seventeen healthy participants were recruited. Measurements were performed twice with one week between sessions. Single-pulse (at 120% and 140% of the resting motor threshold (rMT)) and paired-pulse (2 ms and 15 ms paired pulse) transcranial magnetic stimulation (TMS) were used to elicit MEPs in the SMC which were recorded using sEMG. ≈50% of participants (range: 42-58%; depending on stimulus type/intensity) had significantly different MEP values between day 1 and day 2 for single-pulse and paired-pulse TMS. A large stimulus artefact resulted in MEP responses that could not be assessed in four participants. The assessment of the SMC using sEMG following TMS was poorly reliable for ≈50% of participants. Although using sEMG to assess swallowing musculature function is easier to perform clinically and more comfortable to patients than invasive measures, as the measurement of muscle activity using TMS is unreliable, the use of sEMG for this muscle group is not recommended and requires further research and development. © 2017 John Wiley & Sons Ltd.

  20. Localization of Pathology on Complex Architecture Building Surfaces

    Science.gov (United States)

    Sidiropoulos, A. A.; Lakakis, K. N.; Mouza, V. K.

    2017-02-01

    The technology of 3D laser scanning is considered as one of the most common methods for heritage documentation. The point clouds that are being produced provide information of high detail, both geometric and thematic. There are various studies that examine techniques of the best exploitation of this information. In this study, an algorithm of pathology localization, such as cracks and fissures, on complex building surfaces is being tested. The algorithm makes use of the points' position in the point cloud and tries to distinguish them in two groups-patterns; pathology and non-pathology. The extraction of the geometric information that is being used for recognizing the pattern of the points is being accomplished via Principal Component Analysis (PCA) in user-specified neighborhoods in the whole point cloud. The implementation of PCA leads to the definition of the normal vector at each point of the cloud. Two tests that operate separately examine both local and global geometric criteria among the points and conclude which of them should be categorized as pathology. The proposed algorithm was tested on parts of the Gazi Evrenos Baths masonry, which are located at the city of Giannitsa at Northern Greece.

  1. Uncertainty analysis of point-by-point sampling complex surfaces using touch probe CMMs DOE for complex surfaces verification with CMM

    DEFF Research Database (Denmark)

    Barini, Emanuele Modesto; Tosello, Guido; De Chiffre, Leonardo

    2010-01-01

    The paper describes a study concerning point-by-point sampling of complex surfaces using tactile CMMs. A four factor, two level completely randomized factorial experiment was carried out, involving measurements on a complex surface configuration item comprising a sphere, a cylinder and a cone......, combined in a single assembly. An investigation into the source and effects of different uncertainty contributors during this complex surface measurement was carried out. The factors involved were machine. probe, operator, and procedure dependent. The results obtained from the experiments were analysed...

  2. Supported organometallic complexes: Surface chemistry, spectroscopy, and catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Marks, T.J.

    1990-02-01

    The goal of our program is to define those modes of interaction that take place between organometallic molecules and inorganic surfaces and, ultimately, to correlate various molecule-surface structures with catalytic properties.

  3. Surface complexation at calcium mineral-water interfaces

    OpenAIRE

    Wu, Liuming

    1994-01-01

    Surface reactions occurring at solid-water interfaces in calcium mineral-ligands systems have been studied. Both hydrous apatite and fluorite surfaces show clear amphoteric properties. An ion exchange process between lattice ions of F- on fluorite and OH- ions in bulk solution is discovered. The surface adsorption of Alizarin Red S and sodium oleate are determined. Surface chemical reaction models are established based on acidbase potentiometric titrations, solubility, adsorption and zeta-pot...

  4. HIGH AND LOW RESOLUTION TEXTURED MODELS OF COMPLEX ARCHITECTURAL SURFACES

    Directory of Open Access Journals (Sweden)

    E. K. Stathopoulou

    2012-09-01

    Full Text Available During the recent years it has become obvious that 3D technology, applied mainly with the use of terrestrial laser scanners (TLS is the most suitable technique for the complete geometric documentation of complex objects, whether they are monuments or architectural constructions in general. However, it is rather a challenging task to convert an acquired point cloud into a realistic 3D polygonal model that can simultaneously satisfy high resolution modeling and visualization demands. The aim of the visualization of a simple or complex object is to create a 3D model that best describes the reality within the computer environment. This paper is dedicated especially in the visualization of a complex object's 3D model, through high, as well as low resolution textured models. The object of interest for this study was the Almoina (Romanesque Door of the Cathedral of Valencia in Spain.

  5. High and Low Resolution Textured Models of Complex Architectural Surfaces

    Science.gov (United States)

    Stathopoulou, E. K.; Valanis, A.; Lerma, J. L.; Georgopoulos, A.

    2011-09-01

    During the recent years it has become obvious that 3D technology, applied mainly with the use of terrestrial laser scanners (TLS) is the most suitable technique for the complete geometric documentation of complex objects, whether they are monuments or architectural constructions in general. However, it is rather a challenging task to convert an acquired point cloud into a realistic 3D polygonal model that can simultaneously satisfy high resolution modeling and visualization demands. The aim of the visualization of a simple or complex object is to create a 3D model that best describes the reality within the computer environment. This paper is dedicated especially in the visualization of a complex object's 3D model, through high, as well as low resolution textured models. The object of interest for this study was the Almoina (Romanesque) Door of the Cathedral of Valencia in Spain.

  6. Surface Complexation at the TiO(2) (anatase)/Aqueous Solution Interface: Chemisorption of Catechol.

    Science.gov (United States)

    Rodríguez; Blesa; Regazzoni

    1996-01-15

    Catechol adsorbs at the TiO(2) (anatase)/aqueous solution interface forming inner-sphere surface complexes. The UV-visible differential reflectance spectrum of surface titanium-catecholate complexes presents a band centered at 420 nm which corresponds to the ligand to metal charge transfer transition within the surface complexes. At pH values below pK(a1), the surface excess of catechol is almost insensitive toward pH and presents a Langmuirian dependence with the concentration of uncomplexed catechol. The ratio Gamma(max):N(S) (N(S) being the measured density of available OH surface groups) indicates a prevailing 1 to 2 ligand exchange adsorption stoichiometry. In the range pH >/= pK(a1), the catechol surface excess decreases markedly with increasing pH. Formation of 1 to 1 surface complexes produces an excess of negative surface charge that is revealed by the shift of the iep to lower pH values. The reported data, which are supplemented with information on the charging behavior of TiO(2) suspended in indifferent electrolyte solutions, are interpreted in terms of the multi-site surface complexation model. In this model, two types of surface OH groups are considered: identical withTiOH(1/3-) and identical withOH(1/3+). Although both surface groups undergo protonation-deprotonation reactions, only identical withTiOH(1/3-) are prone to chemisorption.

  7. Supported organometallic complexes: Surface chemistry, spectroscopy, and catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Marks, T.J.

    1992-02-01

    The long-range goal of this project is to elucidate and understand the surface chemistry and catalytic properties of well-defined, highly-reactive organometallic molecules (principally based upon abundant actinide, lanthanide, and early transition elements) adsorbed on metal oxides and halides. The nature of the adsorbed species is probed by a battery of chemical and physicochemical techniques, to understand the nature of the molecular-surface coordination chemistry and how this can give rise to extremely high catalytic activity. A complementary objective is to delineate the scope and mechanisms of the heterogeneous catalytic reactions, as well as to relate them both conceptually and functionally to model systems generated in solution.

  8. QUARRY STABILITY ANALYSIS FOR COMPLEX SLIP SURFACES USING THE MATHSLOPE METHOD

    Directory of Open Access Journals (Sweden)

    Petar Hrženjak

    2004-12-01

    Full Text Available Due to the specific characteristics of rock mass compared to other geological materials, the calculation of rock slope stability is very complex. One of the basic characteristics of rock masses is discontinuity, which, to the most degree, is formed by the geological structure and its elements. Because of discontinuities the slip surfaces of complex shapes are formed in rock slopes, mostly of straight and curved segments. The calculation of the stability factor of rock slopes for complex shapes of slip surfaces has been made possible by the development of the MathSlope method. The complex shape of slip surface has been achieved by introduction of planes of discontinuities in the slip surface. Thus, the setting up and searching procedure of critical slip surfaces of complex shapes is very different in the MathSlope method than in other ones. The example of back analysis for the quarry Vukov Dol shows the successfulness in determining the critical slip surface, as well as the calculation factor of stability for the complex shape of slip surface. Apart from calculating the factor of stability for the complex slip surface, the solution for the position of discontinuity on the slope is obtained, which matches with the real position on the quarry.

  9. Efficient modelling of droplet dynamics on complex surfaces

    Science.gov (United States)

    Karapetsas, George; Chamakos, Nikolaos T.; Papathanasiou, Athanasios G.

    2016-03-01

    This work investigates the dynamics of droplet interaction with smooth or structured solid surfaces using a novel sharp-interface scheme which allows the efficient modelling of multiple dynamic contact lines. The liquid-gas and liquid-solid interfaces are treated in a unified context and the dynamic contact angle emerges simply due to the combined action of the disjoining and capillary pressure, and viscous stresses without the need of an explicit boundary condition or any requirement for the predefinition of the number and position of the contact lines. The latter, as it is shown, renders the model able to handle interfacial flows with topological changes, e.g. in the case of an impinging droplet on a structured surface. Then it is possible to predict, depending on the impact velocity, whether the droplet will fully or partially impregnate the structures of the solid, or will result in a ‘fakir’, i.e. suspended, state. In the case of a droplet sliding on an inclined substrate, we also demonstrate the built-in capability of our model to provide a prediction for either static or dynamic contact angle hysteresis. We focus our study on hydrophobic surfaces and examine the effect of the geometrical characteristics of the solid surface. It is shown that the presence of air inclusions trapped in the micro-structure of a hydrophobic substrate (Cassie-Baxter state) result in the decrease of contact angle hysteresis and in the increase of the droplet migration velocity in agreement with experimental observations for super-hydrophobic surfaces. Moreover, we perform 3D simulations which are in line with the 2D ones regarding the droplet mobility and also indicate that the contact angle hysteresis may be significantly affected by the directionality of the structures with respect to the droplet motion.

  10. Determination of Critical Slip Surface of Soil Slope by New Complex Method

    Institute of Scientific and Technical Information of China (English)

    Li Liang; Chi Shichun; Lin Gao

    2006-01-01

    A new complex method is presented considering not only the improvement upon the "bad "design point, but also the diversity of the newly generated complex, which is obtained by replacing the "bad "design point with the better design point located at the line between the "bad "design point and the centroid of the remaining design points of the old complex. The new complex method is apphed to searching for the critical slip surface of two non-homogeneous soil slopes. The comparison of the results obtained by the new complex method with that by the basic complex method shows that the new complex method is much more likely to find the true critical surface for the randomly generated initial complex.

  11. Complex Surface Concentration Gradients by Stenciled "Electro Click Chemistry"

    DEFF Research Database (Denmark)

    Hansen, Thomas Steen; Lind, Johan Ulrik; Daugaard, Anders Egede;

    2010-01-01

    Complex one- or two-dimensional concentration gradients of alkynated molecules are produced on azidized conducting polymer substrates by stenciled "electro click chemistry". The latter describes the local electrochemical generation of catalytically active Cu(I) required to complete a "click...... active ligands including cell binding peptides are patterned in gradients by this method without losing their biological function or the conductivity of the polymer....

  12. Visualization of pool boiling from complex surfaces with internal tunnels

    Directory of Open Access Journals (Sweden)

    Pastuszko Robert

    2012-04-01

    Full Text Available The paper presents experimental investigations of boiling heat transfer for a system of connected narrow horizontal and vertical tunnels. These extended surfaces, named narrow tunnel structure (NTS, can be applied to electronic element cooling. The experiments were carried out with ethanol at atmospheric pressure. The tunnel external covers were manufactured out of 0.1 mm thick perforated copper foil (hole diameters 0.5 mm, sintered with the mini-fins, formed on the vertical side of the 10 mm high rectangular fins and horizontal inter-fin surface. Visualization studies were conducted with a transparent structured model of joined narrow tunnels limited with the perforated foil. The visualization investigations aimed to formulate assumptions for the boiling model through distinguishing boiling types and defining all phases of bubble growth.

  13. Uncertainty analysis of point by point sampling complex surfaces using touch probe CMMs

    DEFF Research Database (Denmark)

    Barini, Emanuele; Tosello, Guido; De Chiffre, Leonardo

    2007-01-01

    The paper describes a study concerning point by point scanning of complex surfaces using tactile CMMs. A four factors-two level full factorial experiment was carried out, involving measurements on a complex surface configuration item comprising a sphere, a cylinder and a cone, combined in a single...... assembly. An investigation on the source and effects of different uncertainty contributors during this complex surface measurement was carried out. The factors involved are machine, probe, and operator, as well as procedure, dependant. The results obtained from the experiments were analysed in terms...

  14. Intersections of potential energy surfaces of short-lived states: the complex analogue of conical intersections.

    Science.gov (United States)

    Feuerbacher, Sven; Sommerfeld, Thomas; Cederbaum, Lorenz S

    2004-02-15

    Whereas conical intersections between potential energy surfaces of bound states are well known, the interaction of short-lived states has been investigated only rarely. Here, we present several systematically constructed model Hamiltonians to study the topology of intersecting complex potential energy surfaces describing short-lived states: We find the general phenomenon of doubly intersecting complex energy surfaces, i.e., there are two points instead of one as in the case of bound states where the potential energy surfaces coalesce. In addition, seams of intersections of the respective real and imaginary parts of the potential energy surfaces emanate from these two points. Using the Sigma* and Pi* resonance states of the chloroethene anion as a practical example, we demonstrate that our complete linear model Hamiltonian is able to reproduce all phenomena found in explicitly calculated ab initio complex potential energy surfaces.

  15. Graph Complexes and the Moduli Space of Riemann Surfaces

    DEFF Research Database (Denmark)

    Egas Santander, Daniela

    configurations. We use Hatcher's proof of the contractibility of the arc complex to give a new proof of a result of Godin, which states that the category of admissible fat graphs is a model of the mapping class group of open-closed cobordisms. We use this to give a new proof of Costello's result...... potentially allow to transfer constructions in fat graphs to the black and white model. Moreover, we compare Bödigheimer's radial slit configurations and the space of metric admissible fat graphs, producing an explicit homotopy equivalence using a "critical graph" map. This critical graph map descends...... of the punctured disk are trivial; and to give two infinite families of non-trivial classes of the homology of Sullivan diagrams which represent non-trivial string operations.i...

  16. Assembly, characterization, and electrochemical properties of immobilized metal bipyridyl complexes on silicon(111) surfaces.

    Science.gov (United States)

    Lattimer, Judith R C; Blakemore, James D; Sattler, Wesley; Gul, Sheraz; Chatterjee, Ruchira; Yachandra, Vittal K; Yano, Junko; Brunschwig, Bruce S; Lewis, Nathan S; Gray, Harry B

    2014-10-28

    Silicon(111) surfaces have been functionalized with mixed monolayers consisting of submonolayer coverages of immobilized 4-vinyl-2,2'-bipyridyl (1, vbpy) moieties, with the remaining atop sites of the silicon surface passivated by methyl groups. As the immobilized bipyridyl ligands bind transition metal ions, metal complexes can be assembled on the silicon surface. X-ray photoelectron spectroscopy (XPS) demonstrates that bipyridyl complexes of [Cp*Rh], [Cp*Ir], and [Ru(acac)2] were formed on the surface (Cp* is pentamethylcyclopentadienyl, acac is acetylacetonate). For the surface prepared with Ir, X-ray absorption spectroscopy at the Ir LIII edge showed an edge energy as well as post-edge features that were essentially identical with those observed on a powder sample of [Cp*Ir(bpy)Cl]Cl (bpy is 2,2'-bipyridyl). Charge-carrier lifetime measurements confirmed that the silicon surfaces retain their highly favorable photoelectronic properties upon assembly of the metal complexes. Electrochemical data for surfaces prepared on highly doped, n-type Si(111) electrodes showed that the assembled molecular complexes were redox active. However the stability of the molecular complexes on the surfaces was limited to several cycles of voltammetry.

  17. Direct observation of surface reconstruction and termination on a complex metal oxide catalyst by electron microscopy

    KAUST Repository

    Zhu, Yihan

    2012-03-19

    On the surface: The surface reconstruction of an MoVTeO complex metal oxide catalyst was observed directly by various electron microscopic techniques and the results explain the puzzling catalytic behavior. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Surface complexation modeling of neptunium(V) sorption to lepidocrocite (γ-FeOOH)

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Chunli [China Institute of Atomic Energy, Beijing (China). Radiochemistry Div.; Lawrence Berkeley National Laboratory, Berkeley, CA (United States). Chemical Sciences Div.; Powell, Brian A. [Clemson Univ., Anderson, SC (United States). Dept. of Environmental Engineering and Earth Sciences; Zhang, Shengdong [China Institute of Atomic Energy, Beijing (China). Radiochemistry Div.; Rao, Linfeng [Lawrence Berkeley National Laboratory, Berkeley, CA (United States). Chemical Sciences Div.

    2015-07-01

    Lepidocrocite (γ-FeOOH), an important iron-bearing mineral found to exist with a relatively high abundance in the soils of the Chinese nuclear test sites, has rarely been studied for its sorption of transuranic elements from the nuclear wastes. This work develops a quantitative surface complexation model describing the sorption and speciation of Np(V) on synthetic lepidocrocite (γ-FeOOH). Batch sorption experiments on γ-FeOOH were performed under a range of conditions (25 C, 0.1 M NaClO{sub 4}, pH=4-11, 5 μM Np(V), and atmospheric conditions). The Diffuse Layer Model (DLM) was applied to describe the surface-complexation reaction. The data were best-fitted with a single surface-complexation reaction, (≡XOH + NpO{sub 2}{sup +} = XONpO{sub 2}{sup 0} + H{sup +}) that occurred at the lepidocrocite/water interface to form an inner-sphere Np(V) complex with lepidocrocite. The results are complemented by the NpL{sub III}-edge EXAFS data that show that Np(V) was absorbed on γ-FeOOH as monomeric neptunyl ions, with no observations of multinuclear surface complexes or surface precipitates. A prominent peak at ∝3 Aa in the EXAFS Fourier Transform spectra can be attributed to a Np-Fe scattering path, consistent with the formation of an inner sphere Np(V)-lepidocrocite surface complex. Formation of aqueous NpO{sub 2}(CO{sub 3}){sub x}{sup 1-2x} complexes prevents Np(V) sorption at higher pH values but it is unclear if ternary lepidocrocite-Np-carbonate complexes may also form. These data indicate that there are subtle differences in Np(V) interactions with hematite, goethite, and lepidocrocite which is likely a manifestation of the differences in surface reactivity of the three minerals.

  19. Cell surface expression and function of the macromolecular C1 complex on the surface of human monocytes

    Directory of Open Access Journals (Sweden)

    Kinga K Hosszu

    2012-03-01

    Full Text Available The synthesis of the subunits of the C1 complex (C1q, C1s, C1r, and its regulator C1 inhibitor (C1-Inh by human monocytes has been previously established. However, surface expression of these molecules by monocytes has not been shown. Using flow cytometry and antigen-capture ELISA, we show here for the first time that, in addition to C1q, PB monocytes and the monocyte-derived U937 cells express C1s and C1r, as well as Factor B and C1-Inh on their surface. C1s and C1r immunoprecipitated with C1q, suggesting that at least some of the C1q on these cells is part of the C1 complex. Furthermore, the C1 complex on U937 cells was able to trigger complement activation via the classical pathway. The presence of C1-Inh may ensure that an unwarranted autoactivation of the C1 complex does not take place. Since C1-Inh closely monitors the activation of the C1 complex in a sterile or infectious inflammatory environment, further elucidation of the role of C1 complex is crucial to dissect its function in monocyte, DC and T cell activities, and its implications in host defense and tolerance.

  20. Surface estimation methods with phased-arrays for adaptive ultrasonic imaging in complex components

    Science.gov (United States)

    Robert, S.; Calmon, P.; Calvo, M.; Le Jeune, L.; Iakovleva, E.

    2015-03-01

    Immersion ultrasonic testing of structures with complex geometries may be significantly improved by using phased-arrays and specific adaptive algorithms that allow to image flaws under a complex and unknown interface. In this context, this paper presents a comparative study of different Surface Estimation Methods (SEM) available in the CIVA software and used for adaptive imaging. These methods are based either on time-of-flight measurements or on image processing. We also introduce a generalized adaptive method where flaws may be fully imaged with half-skip modes. In this method, both the surface and the back-wall of a complex structure are estimated before imaging flaws.

  1. Surface complexation model for strontium sorption to amorphous silica and goethite

    Directory of Open Access Journals (Sweden)

    Criscenti Louise J

    2008-01-01

    Full Text Available Abstract Strontium sorption to amorphous silica and goethite was measured as a function of pH and dissolved strontium and carbonate concentrations at 25°C. Strontium sorption gradually increases from 0 to 100% from pH 6 to 10 for both phases and requires multiple outer-sphere surface complexes to fit the data. All data are modeled using the triple layer model and the site-occupancy standard state; unless stated otherwise all strontium complexes are mononuclear. Strontium sorption to amorphous silica in the presence and absence of dissolved carbonate can be fit with tetradentate Sr2+ and SrOH+ complexes on the β-plane and a monodentate Sr2+complex on the diffuse plane to account for strontium sorption at low ionic strength. Strontium sorption to goethite in the absence of dissolved carbonate can be fit with monodentate and tetradentate SrOH+ complexes and a tetradentate binuclear Sr2+ species on the β-plane. The binuclear complex is needed to account for enhanced sorption at hgh strontium surface loadings. In the presence of dissolved carbonate additional monodentate Sr2+ and SrOH+ carbonate surface complexes on the β-plane are needed to fit strontium sorption to goethite. Modeling strontium sorption as outer-sphere complexes is consistent with quantitative analysis of extended X-ray absorption fine structure (EXAFS on selected sorption samples that show a single first shell of oxygen atoms around strontium indicating hydrated surface complexes at the amorphous silica and goethite surfaces. Strontium surface complexation equilibrium constants determined in this study combined with other alkaline earth surface complexation constants are used to recalibrate a predictive model based on Born solvation and crystal-chemistry theory. The model is accurate to about 0.7 log K units. More studies are needed to determine the dependence of alkaline earth sorption on ionic strength and dissolved carbonate and sulfate concentrations for the development of

  2. Features of electromagnetic waves in a complex plasma due to surface plasmon resonances on macroparticles

    CERN Document Server

    Vladimirov, S V

    2015-01-01

    The dielectric properties of complex plasma containing either metal or dielectric spherical inclusions (macroparticles, dust) are investigated. We focus on surface plasmon resonances on the macroparticle surfaces and their effect on electromagnetic wave propagation. It is demonstrated that the presence of surface plasmon oscillations significantly modifies plasma electromagnetic properties by resonances and cutoffs in the effective permittivity. This leads to related branches of electromagnetic waves and to the wave band gaps. The results are discussed in the context of dusty plasma experiments.

  3. Multifunctionality of organometallic quinonoid metal complexes: surface chemistry, coordination polymers, and catalysts.

    Science.gov (United States)

    Kim, Sang Bok; Pike, Robert D; Sweigart, Dwight A

    2013-11-19

    Quinonoid metal complexes have potential applications in surface chemistry, coordination polymers, and catalysts. Although quinonoid manganese tricarbonyl complexes have been used as secondary building units (SBUs) in the formation of novel metal-organometallic coordination networks and polymers, the potentially wider applications of these versatile linkers have not yet been recognized. In this Account, we focus on these diverse new applications of quinonoid metal complexes, and report on the variety of quinonoid metal complexes that we have synthesized. Through the use of [(η(6)-hydroquinone)Mn(CO)3](+), we are able to modify the surface of Fe3O4 and FePt nanoparticles (NPs). This process occurs either by the replacement of oleylamine with neutral [(η(5)-semiquinone)Mn(CO)3] at the NP surface, or by the binding of anionic [(η(4)-quinone)Mn(CO)3](-) upon further deprotonation of [(η(5)-semiquinone)Mn(CO)3] at the NP surface. We have demonstrated chemistry at the intersection of surface-modified NPs and coordination polymers through the growth of organometallic coordination polymers onto the surface modified Fe3O4 NPs. The resulting magnetic NP/organometallic coordination polymer hybrid material exhibited both the unique superparamagnetic behavior associated with Fe3O4 NPs and the paramagnetism attributable to the metal nodes, depending upon the magnetic range examined. By the use of functionalized [(η(5)-semiquinone)Mn(CO)3] complexes, we attained the formation of an organometallic monolayer on the surface of highly ordered pyrolitic graphite (HOPG). The resulting organometallic monolayer was not simply a random array of manganese atoms on the surface, but rather consisted of an alternating "up and down" spatial arrangement of Mn atoms extending from the HOPG surface due to hydrogen bonding of the quinonoid complexes. We also showed that the topology of metal atoms on the surface could be controlled through the use of quinonoid metal complexes. A quinonoid

  4. Reactive surface organometallic complexes observed using dynamic nuclear polarization surface enhanced NMR spectroscopy

    KAUST Repository

    Pump, Eva

    2016-08-15

    Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy (DNP SENS) is an emerging technique that allows access to high-sensitivity NMR spectra from surfaces. However, DNP SENS usually requires the use of radicals as an exogenous source of polarization, which has so far limited applications for organometallic surface species to those that do not react with the radicals. Here we show that reactive surface species can be studied if they are immobilized inside porous materials with suitably small windows, and if bulky nitroxide bi-radicals (here TEKPol) are used as the polarization source and which cannot enter the pores. The method is demonstrated by obtaining significant DNP enhancements from highly reactive complelxes [(equivalent to Si-O-)W(Me)(5)] supported on MCM-41, and effects of pore size (6.0, 3.0 and 2.5 nm) on the performance are discussed.

  5. Differential topology of complex surfaces elliptic surfaces with p g=1 smooth classification

    CERN Document Server

    Morgan, John W

    1993-01-01

    This book is about the smooth classification of a certain class of algebraicsurfaces, namely regular elliptic surfaces of geometric genus one, i.e. elliptic surfaces with b1 = 0 and b2+ = 3. The authors give a complete classification of these surfaces up to diffeomorphism. They achieve this result by partially computing one of Donalson's polynomial invariants. The computation is carried out using techniques from algebraic geometry. In these computations both thebasic facts about the Donaldson invariants and the relationship of the moduli space of ASD connections with the moduli space of stable bundles are assumed known. Some familiarity with the basic facts of the theory of moduliof sheaves and bundles on a surface is also assumed. This work gives a good and fairly comprehensive indication of how the methods of algebraic geometry can be used to compute Donaldson invariants.

  6. Cork-resin ablative insulation for complex surfaces and method for applying the same

    Science.gov (United States)

    Walker, H. M.; Sharpe, M. H.; Simpson, W. G. (Inventor)

    1980-01-01

    A method of applying cork-resin ablative insulation material to complex curved surfaces is disclosed. The material is prepared by mixing finely divided cork with a B-stage curable thermosetting resin, forming the resulting mixture into a block, B-stage curing the resin-containing block, and slicing the block into sheets. The B-stage cured sheet is shaped to conform to the surface being insulated, and further curing is then performed. Curing of the resins only to B-stage before shaping enables application of sheet material to complex curved surfaces and avoids limitations and disadvantages presented in handling of fully cured sheet material.

  7. Mass action expressions for bidentate adsorption in surface complexation modeling: theory and practice.

    Science.gov (United States)

    Wang, Zimeng; Giammar, Daniel E

    2013-05-07

    The inclusion of multidentate adsorption reactions has improved the ability of surface complexation models (SCM) to predict adsorption to mineral surfaces, but variation in the mass action expression for these reactions has caused persistent ambiguity and occasional mishandling. The principal differences are the exponent (α) for the activity of available surface sites and the inclusion of surface site activity on a molar concentration versus fraction basis. Exemplified by bidentate surface complexation, setting α at two within the molar-based framework will cause critical errors in developing a self-consistent model. Despite the publication of several theoretical discussions regarding appropriate approaches, mishandling and confusion has persisted in the model applications involving multidentate surface complexes. This review synthesizes the theory of modeling multidentate surface complexes in a style designed to enable improvements in SCM practice. The implications of selecting an approach for multidentate SCM are illustrated with a previously published data set on U(VI) adsorption to goethite. To improve the translation of theory into improved practice, the review concludes with suggestions for handling multidentate reactions and publishing results that can avoid ambiguity or confusion. Although most discussion is exemplified by the generic bidentate case, the general issues discussed are relevant to higher denticity adsorption.

  8. Complex Entangling Surfaces for AdS and Lifshitz Black Holes?

    CERN Document Server

    Fischetti, Sebastian

    2014-01-01

    We discuss the possible relevance of complex codimension-two extremal surfaces to the the Ryu-Takayanagi holographic entanglement proposal and its covariant Hubeny-Rangamani-Takayanagi (HRT) generalization. Such surfaces live in a complexified bulk spacetime defined by analytic continuation. We identify surfaces of this type for BTZ, Schwarzschild-AdS, and Schwarzschild-Lifshitz planar black holes. Since the dual CFT interpretation for the imaginary part of their areas is unclear, we focus on a straw man proposal relating CFT entropy to the real part of the area alone. For Schwarzschild-AdS and Schwarzschild-Lifshitz, we identify families where the real part of the area agrees with qualitative physical expectations for the appropriate CFT entropy and, in addition, where it is smaller than the area of corresponding real extremal surfaces. It is thus plausible that the CFT entropy is controlled by these complex extremal surfaces.

  9. Synthesis in situ of gold nanoparticles by a dialkynyl Fischer carbene complex anchored to glass surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bertolino, María Candelaria, E-mail: cbertolino@fcq.unc.edu.ar; Granados, Alejandro Manuel, E-mail: ale@fcq.unc.edu.ar

    2016-10-15

    Highlights: • Fischer carbene 1-W reacts via cycloaddition without Cu(I) with azide terminal surface. • This reaction on the surface is regioselective to internal triple bond of 1-W. • 1-W bound to glass surface produce AuNps in situ fixed to the surface. • This ability is independent of how 1-W is bonded to the surface. • This hybrid surface can be valuable as SERS substrate or in heterogeneous catalysis. - Abstract: In this work we present a detailed study of classic reactions such as “click reaction” and nucleophilic substitution reaction but on glass solid surface (slides). We used different reactive center of a dialkynylalcoxy Fischer carbene complex of tungsten(0) to be anchored to modified glass surface with amine, to obtain aminocarbene, and azide terminal groups. These cycloaddition reaction showed regioselectivity to internal triple bond of dialkynyl Fischer carbene complex without Cu(I) as catalyst. Anyway the carbene anchored was able to act as a reducing agent to produce in situ very stable gold nanoparticles fixed on surface. We showed the characterization of modified glasses by contact angle measurements and XPS. Synthesized nanoparticles were characterized by SEM, XPS, EDS and UV–vis. The modified glasses showed an important enhancement Raman-SERS. This simple, fast and robust method to create a polifunctional and hybrid surfaces can be valuable in a wide range of applications such as Raman-SERS substrates and other optical fields.

  10. Uniform surface polished method of complex holes in abrasive flow machining

    Institute of Scientific and Technical Information of China (English)

    A-Cheng WANG; Lung TSAI; Kuo-Zoo LIANG; Chun-Ho LIU; Shi-Hong WENG

    2009-01-01

    Abrasive flow machining(AFM) is an effective method that can remove the recasting layer produced by wire electrical discharge machining(WEDM). However, the surface roughness will not be easily uniform when a complex hole is polished by this method. CFD numerical method is aided to design good passageways to find the smooth roughness on the complex hole in AFM. Through the present method, it reveals that the shear forces in the polishing process and the flow properties of the medium in AFM play the roles in controlling the roughness on the entire surface. A power law model was firstly set up by utilizing the effect of shear rates on the medium viscosities, and the coefficients of the power law would be found by solving the algebraic equation from the relations between the shear rates and viscosities. Then the velocities, strain rates and shear forces of the medium acting on the surface would be obtained in the constant pressure by CFD software. Finally, the optimal mold core put into the complex hole could be designed after these simulations. The results show that the shear forces and strain rates change sharply on the entire surface if no mold core is inserted into the complex hole, whereas they hardly make any difference when the core shape is similar to the complex hole. Three experimental types of mold core were used. The results demonstrate that the similar shape of the mold core inserted into the hole could find the uniform roughness on the surface.

  11. Surface tension method for determining binding constants for cyclodextrin inclusion complexes of ionic surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Dharmawardana, U.R.; Christian, S.D.; Tucker, E.E.; Taylor, R.W.; Scamehorn, J.F. (Univ. of Oklahoma, Norman, OK (United States))

    1993-09-01

    A new method has been developed for determining binding constants of complexes of cyclodextrins with surface-active compounds, including water-soluble ionic surfactants. The technique requires measuring the change in surface tension caused by addition of a cyclodextrin (CD) to aqueous solutions of the surfactant; the experimental results lead directly to inferred values of the thermodynamic activity of the surfactant. Surface tension results are reported for three different surfactants sodium dodecyl sulfate (SDS), cetylpyridinium chloride (CPC), and cetyltrimethylammonium bromide (CTAB) in the presence and in the absence of added [beta]-CD. Data for CPC have been obtained at surfactant concentrations below and above the critical micelle concentration. Correlations between surface tension and surfactant activity are expressed by the Szyszkowski equation, which subsumes the Langmuir adsorption model and the Gibbs equation. It is observed that the surface tension increases monotonically as [beta]-cyclodextrin is added to ionic surfactant solutions. At concentrations of CD well in excess of the surfactant concentration, the surface tension approaches that of pure water, indicating that neither the surfactant-CD complexes nor CD itself are surface active. Binding constants are inferred from a model that incorporates the parameters of the Szyszkowski equation and mass action constants relating to the formation of micelles from monomers of the surfactant and the counterion. Evidence is given that two molecules of CD can complex the C-16 hydrocarbon chain of the cetyl surfactants. 30 refs., 5 figs., 1 tab.

  12. Oriented coupling of major histocompatibility complex (MHC) to sensor surfaces using light assisted immobilisation technology

    DEFF Research Database (Denmark)

    Snabe, Torben; Røder, Gustav Andreas; Neves-Petersen, Maria Teresa;

    2005-01-01

    histocompatibility complex (MHC class I) to a sensor surface is presented. The coupling was performed using light assisted immobilisation--a novel immobilisation technology which allows specific opening of particular disulphide bridges in proteins which then is used for covalent bonding to thiol-derivatised surfaces...... via a new disulphide bond. Light assisted immobilisation specifically targets the disulphide bridge in the MHC-I molecule alpha(3)-domain which ensures oriented linking of the complex with the peptide binding site exposed away from the sensor surface. Structural analysis reveals that a similar...... procedure can be used for covalent immobilisation of MHC class II complexes. The results open for the development of efficient T cell sensors, sensors for recognition of peptides of pathogenic origin, as well as other applications that may benefit from oriented immobilisation of MHC proteins....

  13. Adsorption of heterogeneously charged nanoparticles on a variably charged surface by the extended surface complexation approach: Charge regulation, chemical heterogeneity, and surface complexation

    NARCIS (Netherlands)

    Saito, T.; Koopal, L.K.; Nagasaki, S.; Tanaka, S.

    2008-01-01

    Adsorption of randomly branched polyelectrolytes, hairy particles and internally structured macromolecules, collectively denoted as heterogeneously charged nanoparticles, on charged surfaces is important in. many technological and natural processes. In this paper, we will focus on (1) the charge

  14. Adsorption of heterogeneously charged nanoparticles on a variably charged surface by the extended surface complexation approach: Charge regulation, chemical heterogeneity, and surface complexation

    NARCIS (Netherlands)

    Saito, T.; Koopal, L.K.; Nagasaki, S.; Tanaka, S.

    2008-01-01

    Adsorption of randomly branched polyelectrolytes, hairy particles and internally structured macromolecules, collectively denoted as heterogeneously charged nanoparticles, on charged surfaces is important in. many technological and natural processes. In this paper, we will focus on (1) the charge reg

  15. Actinides sorption onto hematite. Experimental data, surface complexation modeling and linear free energy relationship

    Energy Technology Data Exchange (ETDEWEB)

    Romanchuk, Anna Y.; Kalmykov, Stephan N. [Lomonosov Moscow State Univ., Moscow (Russian Federation). Dept. of Chemistry

    2014-07-01

    The sorption of actinides in different valence states - Am(III), Th(IV), Np(V) and U(VI) onto hematite have been revisited with the special emphasis on the equilibrium constants of formation of surface species. The experimental sorption data have been treated using surface complexation modeling from which the set of new values of equilibrium constants were obtained. Formation of inner sphere monodentate surface species adequately describes the pH-sorption edges for actinide ions indicative the ionic electrostatic nature of bonding with small or no covalency contribution. The linear free energy relationship representing the correlation between the hydrolysis constants and surface complexation constants has been developed for various cations including K(I), Li(I), Na(I), Ag(I), Tl(I), Sr(II), Cu(II), Co(II), La(III), Eu(III), Ga(III), Am(III), Th(IV), Np(V), U(VI). (orig.)

  16. Recent developments of surface complexation models applied to environmental aquatic chemistry

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based on numerous latest references, the current developments in surface complexation, surface precipitation and the corresponding models (SCMs and SPMs), were reviewed. The contents involved comparison on surface charge composition and layer-structure of solid-solution interface for the classical 1-pK and 2- pK models, In addition, the fundamental concept and relations of the new models, i.e., multi-site complexation (MUSIC) and charge -distribution (CD) MUSIC models were described as well. To avoid misuse or abuse, it must be emphasized that the applicability nd limitation for each model should be considered carefully when selecting the concerned model(s). In addition, some new powerful techniques for surface characterization and analysis applied to model establishment and modification were also briefly introduced.

  17. A NUMERICAL INVESTIGATION INTO ELECTROOSMOTIC FLOW IN MICROCHANNELS WITH COMPLEX WAVY SURFACES

    Directory of Open Access Journals (Sweden)

    Her-Terng Yau

    2011-01-01

    Full Text Available This study investigates the flow characteristics of electroosmotic flow in a microchannel with complex wavy surfaces. A general method of coordinate transformation is used to solve the governing equations describing the electroosmotic flow in the microchannel. Numerical simulations are performed to analyze the effects of wave amplitude on the electrical field, flow streamlines, and flow fields in the microchannel. The simulation results show that, compared to a traditional pressure-driven flow, flow recirculation is not developed in the electroosmotic flow in a microchannel with complex wavy surfaces. The simulations also show that the electrical field and velocity profiles change along the channel in the region of wavy surfaces. Non-flat velocity profiles are observed in different cross-sections of the channel in the region of wavy surfaces.

  18. Surface Complexation Modeling in Variable Charge Soils: Charge Characterization by Potentiometric Titration

    Directory of Open Access Journals (Sweden)

    Giuliano Marchi

    2015-10-01

    Full Text Available ABSTRACT Intrinsic equilibrium constants of 17 representative Brazilian Oxisols were estimated from potentiometric titration measuring the adsorption of H+ and OH− on amphoteric surfaces in suspensions of varying ionic strength. Equilibrium constants were fitted to two surface complexation models: diffuse layer and constant capacitance. The former was fitted by calculating total site concentration from curve fitting estimates and pH-extrapolation of the intrinsic equilibrium constants to the PZNPC (hand calculation, considering one and two reactive sites, and by the FITEQL software. The latter was fitted only by FITEQL, with one reactive site. Soil chemical and physical properties were correlated to the intrinsic equilibrium constants. Both surface complexation models satisfactorily fit our experimental data, but for results at low ionic strength, optimization did not converge in FITEQL. Data were incorporated in Visual MINTEQ and they provide a modeling system that can predict protonation-dissociation reactions in the soil surface under changing environmental conditions.

  19. Formation of oxygen complexes in controlled atmosphere at surface of doped glassy carbon

    Indian Academy of Sciences (India)

    Aleksandra A Perić-Grujić; Tatjana M Vasiljević; Olivera M Nešković; Miomir V Veljković; Zoran V Laušević; Mila D Laušević

    2006-10-01

    The effects of boron and phosphorus incorporation in phenolic resin precursor to the oxidation resistance of glassy carbon have been studied. In order to reveal the nature and composition of the oxygen complexes formed at the surface of doped glassy carbon, under controlled atmosphere, the surface of the samples was cleaned under vacuum up to 1273 K. Specific functional groups, subsequently formed under dry CO2 or O2 atmosphere on the surface of boron-doped and phosphorus-doped glassy carbon samples, were examined using the temperature-programmed desorption method combined with mass spectrometric analysis. Characterization of surface properties of undoped and doped samples has shown that in the presence of either boron or phosphorus heteroatoms, a lower amount of oxygen complexes formed after CO2 exposure, while, typically, higher amount of oxygen complexes formed after O2 exposure. It has been concluded that the surface of undoped glassy carbon has a greater affinity towards CO2, while in the presence of either boron or phosphorus heteroatoms, the glassy carbon surface affinity becomes greater towards O2, under experimental conditions.

  20. Adsorption of mercury on lignin: combined surface complexation modeling and X-ray absorption spectroscopy studies.

    Science.gov (United States)

    Lv, Jitao; Luo, Lei; Zhang, Jing; Christie, Peter; Zhang, Shuzhen

    2012-03-01

    Adsorption of mercury (Hg) on lignin was studied at a range of pH values using a combination of batch adsorption experiments, a surface complexation model (SCM) and synchrotron X-ray absorption spectroscopy (XAS). Surface complexation modeling indicates that three types of acid sites on lignin surfaces, namely aliphatic carboxylic-, aromatic carboxylic- and phenolic-type surface groups, contributed to Hg(II) adsorption. The bond distance and coordination number of Hg(II) adsorption samples at pH 3.0, 4.0 and 5.5 were obtained from extended X-ray absorption fine structure (EXAFS) spectroscopy analysis. The results of SCM and XAS combined reveal that the predominant adsorption species of Hg(II) on lignin changes from HgCl(2)(0) to monodentate complex -C-O-HgCl and then bidentate complex -C-O-Hg-O-C- with increasing pH value from 2.0 to 6.0. The good agreement between SCM and XAS results provides new insight into understanding the mechanisms of Hg(II) adsorption on lignin.

  1. Integrating Sound Scattering Measurements in the Design of Complex Architectural Surfaces

    DEFF Research Database (Denmark)

    Peters, Brady

    2010-01-01

    is recognized to be one of the most important factors in predicting the computational prediction of acoustic performance. This paper proposes a workflow for the design of complex architectural surfaces and the prediction of their sound scattering properties. This workflow includes the development...

  2. The Complexity of Identifying Ryu-Takayanagi Surfaces in AdS3/CFT2

    CERN Document Server

    Bao, Ning

    2016-01-01

    We present a constructive algorithm for the determination of Ryu-Takayanagi surfaces in AdS3/CFT2 which exploits previously noted connections between holographic entanglement entropy and max-flow/min-cut. We then characterize its complexity as a polynomial time algorithm.

  3. The complexity of identifying Ryu-Takayanagi surfaces in AdS3/CFT2

    Science.gov (United States)

    Bao, N.; Chatwin-Davies, A.

    2016-11-01

    We present a constructive algorithm for the determination of Ryu-Takayanagi surfaces in AdS3/CFT2 which exploits previously noted connections between holographic entanglement entropy and max-flow/min-cut. We then characterize its complexity as a polynomial time algorithm.

  4. Application of surface complexation models to anion adsorption by natural materials

    Science.gov (United States)

    Various chemical models of ion adsorption will be presented and discussed. Chemical models, such as surface complexation models, provide a molecular description of anion adsorption reactions using an equilibrium approach. Two such models, the constant capacitance model and the triple layer model w...

  5. Ab initio potential-energy surface and rovibrational states of the HCN-HCl complex

    NARCIS (Netherlands)

    Avoird, A. van der; Pedersen, T.B.; Dhont, G.S.F.; Fernandez, B.; Koch, H.

    2006-01-01

    A four-dimensional intermolecular potential-energy surface has been calculated for the HCN-HCl complex, with the use of the coupled cluster method with single and double excitations and noniterative inclusion of triples. Data for more than 13 000 geometries were represented by an angular expansion i

  6. Laser Quenching and Ion Sulphidizing Complex Surface Treat Technology for Diesel Engine Cylinder

    Institute of Scientific and Technical Information of China (English)

    XIE Zhaoqian; ZENG Qingqiang; HUANG Huayuan; Cai Zhihai; ZHAO Yuqiang

    2012-01-01

    In order to solve the problem of wear-out-failure of diesel engine cylinder,the laser-quenching and low temperature ion sulfurizing complex surface treatment technology was operated on the surface of 42MnCr52 steel.And the tribological properties of the complex layer were investigated.The experimental results indicated that the complex layer was composed of soft surface sulphide layer and sub-surface laserquenching harden layer,and showed excellent friction-reduction and wear-resistance performance at high temperature.The synergistic effect of the complex layer resulted in 20% increase in hardness,10% reduction in friction coefficient and 50% reduction in wear weight loss,respectively,compared with those of the standard samples.The bench-test further demonstrated that this technology can improve the lubricating condition between cylinder and piston ring,and reduce both abnormity wear when the lubricating oil is deficiency at the time of start-up and sticking wear at high temperature during the operating period,and then prolong the service life of engine.

  7. Inspection of Complex Internal Surface Shape with Fiber-optic Sensor II: for Specular Tilted Surface Measurement

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Complex surface shape measurement has been a focus topic in the CAD/CAM field. A popular method for measuring dimensional information is using a 3D coordinate measuring machine (CMM)with a touch trigger probe. The measurement set up with CMM, however, is a time consuming task and the accuracy of the measurement deteriorates as the speed of measurement increase. Non-contact measurement is favored since high speed measurement can be achieved and problems with vibration and friction can be eliminated. Although much research has been conducted in non-contact measurement using image capturing and processing schemes, accuracy is poor and measurement is limited. Some optical technologies developed provide a good accuracy but the dynamic range and versatility is very limited. A novel fiber-optic sensor used for the inspection of complex internal contours is presented in this paper, which is able to measure a surface shape in a non-contact manner with high accuracy and high speed, and is compact and flexible to be incorporated into a CMM. Modulation functions for tilted surface shape measurement, based on the Gaussian distribution of the emitting beam from single-mode fiber (SMF), were derived for specular reflection. The feasibility of the proposed measurement principle was verified by simulations.

  8. Surface complexation of neptunium (V) onto whole cells and cell componets of Shewanella alga

    Energy Technology Data Exchange (ETDEWEB)

    Reed, Donald Timothy [Los Alamos National Laboratory; Deo, Randhir P [ASU; Rittmann, Bruce E [ASU; Songkasiri, Warinthorn [UNAFFILIATED

    2008-01-01

    We systematically quantified surface complexation of neptunium(V) onto whole cells of Shewanella alga strain BrY and onto cell wall and extracellular polymeric substances (EPS) of S. alga. We first performed acid and base titrations and used the mathematical model FITEQL with constant-capacitance surface-complexation to determine the concentrations and deprotonation constants of specific surface functional groups. Deprotonation constants most likely corresponded to a carboxyl site associated with amino acids (pK{sub a} {approx} 2.4), a carboxyl group not associated with amino acids (pK{sub a} {approx} 5), a phosphoryl site (pK{sub a} {approx} 7.2), and an amine site (pK{sub a} > 10). We then carried out batch sorption experiments with Np(V) and each of the S. alga components at different pHs. Results show that solution pH influenced the speciation of Np(V) and each of the surface functional groups. We used the speciation sub-model of the biogeochemical model CCBATCH to compute the stability constants for Np(V) complexation to each surface functional group. The stability constants were similar for each functional group on S. alga bacterial whole cells, cell walls, and EPS, and they explain the complicated sorption patterns when they are combined with the aqueous-phase speciation of Np(V). For pH < 8, NpO{sub 2}{sup +} was the dominant form of Np(V), and its log K values for the low-pK{sub a} carboxyl, other carboxyl, and phosphoryl groups were 1.75, 1.75, and 2.5 to 3.1, respectively. For pH greater than 8, the key surface ligand was amine >XNH3+, which complexed with NpO{sub 2}(CO{sub 3}){sub 3}{sup 5-}. The log K for NpO{sub 2}(CO{sub 3}){sub 3}{sup 5-} complexed onto the amine groups was 3.1 to 3.6. All of the log K values are similar to those of Np(V) complexes with aqueous carboxyl and N-containing carboxyl ligands. These results point towards the important role of surface complexation in defining key actinide-microbiological interactions in the subsurface.

  9. DNA binding of a non-sequence-specific HMG-D protein is entropy driven with a substantial non-electrostatic contribution.

    Science.gov (United States)

    Dragan, Anatoly I; Klass, Janet; Read, Christopher; Churchill, Mair E A; Crane-Robinson, Colyn; Privalov, Peter L

    2003-08-22

    The thermal properties of two forms of the Drosophila melanogaster HMG-D protein, with and without its highly basic 26 residue C-terminal tail (D100 and D74) and the thermodynamics of their non-sequence-specific interaction with linear DNA duplexes were studied using scanning and titration microcalorimetry, spectropolarimetry, fluorescence anisotropy and FRET techniques at different temperatures and salt concentrations. It was shown that the C-terminal tail of D100 is unfolded at all temperatures, whilst the state of the globular part depends on temperature in a rather complex way, being completely folded only at temperatures close to 0 degrees C and unfolding with significant heat absorption at temperatures below those of the gross denaturational changes. The association constant and thus Gibbs energy of binding for D100 is much greater than for D74 but the enthalpies of their association are similar and are large and positive, i.e. DNA binding is a completely entropy-driven process. The positive entropy of association is due to release of counterions and dehydration upon forming the protein/DNA complex. Ionic strength variation showed that electrostatic interactions play an important but not exclusive role in the DNA binding of the globular part of this non-sequence-specific protein, whilst binding of the positively charged C-terminal tail of D100 is almost completely electrostatic in origin. This interaction with the negative charges of the DNA phosphate groups significantly enhances the DNA bending. An important feature of the non-sequence-specific association of these HMG boxes with DNA is that the binding enthalpy is significantly more positive than for the sequence-specific association of the HMG box from Sox-5, despite the fact that these proteins bend the DNA duplex to a similar extent. This difference shows that the enthalpy of dehydration of apolar groups at the HMG-D/DNA interface is not fully compensated by the energy of van der Waals interactions

  10. Computational Redox Potential Predictions: Applications to Inorganic and Organic Aqueous Complexes, and Complexes Adsorbed to Mineral Surfaces

    Directory of Open Access Journals (Sweden)

    Krishnamoorthy Arumugam

    2014-04-01

    Full Text Available Applications of redox processes range over a number of scientific fields. This review article summarizes the theory behind the calculation of redox potentials in solution for species such as organic compounds, inorganic complexes, actinides, battery materials, and mineral surface-bound-species. Different computational approaches to predict and determine redox potentials of electron transitions are discussed along with their respective pros and cons for the prediction of redox potentials. Subsequently, recommendations are made for certain necessary computational settings required for accurate calculation of redox potentials. This article reviews the importance of computational parameters, such as basis sets, density functional theory (DFT functionals, and relativistic approaches and the role that physicochemical processes play on the shift of redox potentials, such as hydration or spin orbit coupling, and will aid in finding suitable combinations of approaches for different chemical and geochemical applications. Identifying cost-effective and credible computational approaches is essential to benchmark redox potential calculations against experiments. Once a good theoretical approach is found to model the chemistry and thermodynamics of the redox and electron transfer process, this knowledge can be incorporated into models of more complex reaction mechanisms that include diffusion in the solute, surface diffusion, and dehydration, to name a few. This knowledge is important to fully understand the nature of redox processes be it a geochemical process that dictates natural redox reactions or one that is being used for the optimization of a chemical process in industry. In addition, it will help identify materials that will be useful to design catalytic redox agents, to come up with materials to be used for batteries and photovoltaic processes, and to identify new and improved remediation strategies in environmental engineering, for example the

  11. A physically-based hybrid framework to estimate daily-mean surface fluxes over complex terrain

    Science.gov (United States)

    Huang, Hsin-Yuan; Hall, Alex

    2016-06-01

    In this study we developed and examined a hybrid modeling approach integrating physically-based equations and statistical downscaling to estimate fine-scale daily-mean surface turbulent fluxes (i.e., sensible and latent heat fluxes) for a region of southern California that is extensively covered by varied vegetation types over a complex terrain. The selection of model predictors is guided by physical parameterizations of surface flux used in land surface models and analysis showing net shortwave radiation that is a major source of variability in the surface energy budget. Through a structure of multivariable regression processes with an application of near-surface wind estimates from a previous study, we successfully reproduce dynamically-downscaled 3 km resolution surface flux data. The overall error in our estimates is less than 20 % for both sensible and latent heat fluxes, while slightly larger errors are seen in high-altitude regions. The major sources of error in estimates include the limited information provided in coarse reanalysis data, the accuracy of near-surface wind estimates, and an ignorance of the nonlinear diurnal cycle of surface fluxes when using daily-mean data. However, with reasonable and acceptable errors, this hybrid modeling approach provides promising, fine-scale products of surface fluxes that are much more accurate than reanalysis data, without performing intensive dynamical simulations.

  12. Quantitative evaluation and modeling of two-dimensional neovascular network complexity: the surface fractal dimension

    Directory of Open Access Journals (Sweden)

    Franceschini Barbara

    2005-02-01

    Full Text Available Abstract Background Modeling the complex development and growth of tumor angiogenesis using mathematics and biological data is a burgeoning area of cancer research. Architectural complexity is the main feature of every anatomical system, including organs, tissues, cells and sub-cellular entities. The vascular system is a complex network whose geometrical characteristics cannot be properly defined using the principles of Euclidean geometry, which is only capable of interpreting regular and smooth objects that are almost impossible to find in Nature. However, fractal geometry is a more powerful means of quantifying the spatial complexity of real objects. Methods This paper introduces the surface fractal dimension (Ds as a numerical index of the two-dimensional (2-D geometrical complexity of tumor vascular networks, and their behavior during computer-simulated changes in vessel density and distribution. Results We show that Ds significantly depends on the number of vessels and their pattern of distribution. This demonstrates that the quantitative evaluation of the 2-D geometrical complexity of tumor vascular systems can be useful not only to measure its complex architecture, but also to model its development and growth. Conclusions Studying the fractal properties of neovascularity induces reflections upon the real significance of the complex form of branched anatomical structures, in an attempt to define more appropriate methods of describing them quantitatively. This knowledge can be used to predict the aggressiveness of malignant tumors and design compounds that can halt the process of angiogenesis and influence tumor growth.

  13. A closer look at the complex hydrophilic/hydrophobic interactions forces at the human hair surface

    Science.gov (United States)

    Baghdadli, N.; Luengo, G. S.; Recherche, L.

    2008-03-01

    The complex chemical structure of the hair surface is far from being completely understood. Current understanding is based on Rivett's model1 that was proposed to explain the macroscopic hydrophobic nature of the surface of natural hair. In this model covalently-linked fatty acids are chemically grafted to the amorphous protein (keratin) through a thio-ester linkage2,3. Nevertheless, experience like wetting and electrical properties of human hair surface4 shows that the complexity of the hair surface is not fully understand based on this model in literature. Recent studies in our laboratory show for the first time microscopic evidence of the heterogeneous physico-chemical character of the hair surface. By using Chemical Force Microscopy, the presence of hydrophobic and ionic species are detected and localized, before and after a cosmetic treatment (bleaching). Based on force curve analysis the mapping of the local distribution of hydrophilic and hydrophobic groups of hair surface is obtained. A discussion on a more plausible hair model and its implications will be presented based on these new results.

  14. A closer look at the complex hydrophilic/hydrophobic interactions forces at the human hair surface

    Energy Technology Data Exchange (ETDEWEB)

    Baghdadli, N; Luengo, G S; Recherche, L [Avenue Eugene Schueller, Aulnay-Sous Bois, 93100 (France)], E-mail: nbaghdadli@rd.loreal.com, E-mail: gluengo@rd.loreal.com

    2008-03-15

    The complex chemical structure of the hair surface is far from being completely understood. Current understanding is based on Rivett's model{sup 1} that was proposed to explain the macroscopic hydrophobic nature of the surface of natural hair. In this model covalently-linked fatty acids are chemically grafted to the amorphous protein (keratin) through a thio-ester linkage{sup 2,3}. Nevertheless, experience like wetting and electrical properties of human hair surface{sup 4} shows that the complexity of the hair surface is not fully understand based on this model in literature. Recent studies in our laboratory show for the first time microscopic evidence of the heterogeneous physico-chemical character of the hair surface. By using Chemical Force Microscopy, the presence of hydrophobic and ionic species are detected and localized, before and after a cosmetic treatment (bleaching). Based on force curve analysis the mapping of the local distribution of hydrophilic and hydrophobic groups of hair surface is obtained. A discussion on a more plausible hair model and its implications will be presented based on these new results.

  15. Chromate adsorption on selected soil minerals: Surface complexation modeling coupled with spectroscopic investigation

    Energy Technology Data Exchange (ETDEWEB)

    Veselská, Veronika, E-mail: veselskav@fzp.czu.cz [Department of Environmental Geosciences, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcka 129, CZ-16521, Prague (Czech Republic); Fajgar, Radek [Department of Analytical and Material Chemistry, Institute of Chemical Process Fundamentals of the CAS, v.v.i., Rozvojová 135/1, CZ-16502, Prague (Czech Republic); Číhalová, Sylva [Department of Environmental Geosciences, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcka 129, CZ-16521, Prague (Czech Republic); Bolanz, Ralph M. [Institute of Geosciences, Friedrich-Schiller-University Jena, Carl-Zeiss-Promenade 10, DE-07745, Jena (Germany); Göttlicher, Jörg; Steininger, Ralph [ANKA Synchrotron Radiation Facility, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, DE-76344, Eggenstein-Leopoldshafen (Germany); Siddique, Jamal A.; Komárek, Michael [Department of Environmental Geosciences, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcka 129, CZ-16521, Prague (Czech Republic)

    2016-11-15

    Highlights: • Study of Cr(VI) adsorption on soil minerals over a large range of conditions. • Combined surface complexation modeling and spectroscopic techniques. • Diffuse-layer and triple-layer models used to obtain fits to experimental data. • Speciation of Cr(VI) and Cr(III) was assessed. - Abstract: This study investigates the mechanisms of Cr(VI) adsorption on natural clay (illite and kaolinite) and synthetic (birnessite and ferrihydrite) minerals, including its speciation changes, and combining quantitative thermodynamically based mechanistic surface complexation models (SCMs) with spectroscopic measurements. Series of adsorption experiments have been performed at different pH values (3–10), ionic strengths (0.001–0.1 M KNO{sub 3}), sorbate concentrations (10{sup −4}, 10{sup −5}, and 10{sup −6} M Cr(VI)), and sorbate/sorbent ratios (50–500). Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy were used to determine the surface complexes, including surface reactions. Adsorption of Cr(VI) is strongly ionic strength dependent. For ferrihydrite at pH <7, a simple diffuse-layer model provides a reasonable prediction of adsorption. For birnessite, bidentate inner-sphere complexes of chromate and dichromate resulted in a better diffuse-layer model fit. For kaolinite, outer-sphere complexation prevails mainly at lower Cr(VI) loadings. Dissolution of solid phases needs to be considered for better SCMs fits. The coupled SCM and spectroscopic approach is thus useful for investigating individual minerals responsible for Cr(VI) retention in soils, and improving the handling and remediation processes.

  16. Surface complexation modeling of Cu(II adsorption on mixtures of hydrous ferric oxide and kaolinite

    Directory of Open Access Journals (Sweden)

    Schaller Melinda S

    2008-09-01

    Full Text Available Abstract Background The application of surface complexation models (SCMs to natural sediments and soils is hindered by a lack of consistent models and data for large suites of metals and minerals of interest. Furthermore, the surface complexation approach has mostly been developed and tested for single solid systems. Few studies have extended the SCM approach to systems containing multiple solids. Results Cu adsorption was measured on pure hydrous ferric oxide (HFO, pure kaolinite (from two sources and in systems containing mixtures of HFO and kaolinite over a wide range of pH, ionic strength, sorbate/sorbent ratios and, for the mixed solid systems, using a range of kaolinite/HFO ratios. Cu adsorption data measured for the HFO and kaolinite systems was used to derive diffuse layer surface complexation models (DLMs describing Cu adsorption. Cu adsorption on HFO is reasonably well described using a 1-site or 2-site DLM. Adsorption of Cu on kaolinite could be described using a simple 1-site DLM with formation of a monodentate Cu complex on a variable charge surface site. However, for consistency with models derived for weaker sorbing cations, a 2-site DLM with a variable charge and a permanent charge site was also developed. Conclusion Component additivity predictions of speciation in mixed mineral systems based on DLM parameters derived for the pure mineral systems were in good agreement with measured data. Discrepancies between the model predictions and measured data were similar to those observed for the calibrated pure mineral systems. The results suggest that quantifying specific interactions between HFO and kaolinite in speciation models may not be necessary. However, before the component additivity approach can be applied to natural sediments and soils, the effects of aging must be further studied and methods must be developed to estimate reactive surface areas of solid constituents in natural samples.

  17. Evidence for Carbonate Surface Complexation during Forsterite Carbonation in Wet Supercritical Carbon Dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Loring, John S.; Chen, Jeffrey; Benezeth Ep Gisquet, Pascale; Qafoku, Odeta; Ilton, Eugene S.; Washton, Nancy M.; Thompson, Christopher J.; Martin, Paul F.; McGrail, B. Peter; Rosso, Kevin M.; Felmy, Andrew R.; Schaef, Herbert T.

    2015-07-14

    Continental flood basalts are attractive formations for geologic sequestration of carbon dioxide because of their reactive divalent-cation containing silicates, such as forsterite (Mg2SiO4), suitable for long-term trapping of CO2 mineralized as metal carbonates. The goal of this study was to investigate at a molecular level the carbonation products formed during the reaction of forsterite with supercritical CO2 (scCO2) as a function of the concentration of H2O adsorbed to the forsterite surface. Experiments were performed at 50 °C and 90 bar using an in situ IR titration capability, and post-reaction samples were examined by ex situ techniques, including SEM, XPS, FIB-TEM, TGA-MS, and MAS-NMR. Carbonation products and reaction extents varied greatly with adsorbed H2O. We show for the first time evidence of Mg-carbonate surface complexation under wet scCO2 conditions. Carbonate is found to be coordinated to Mg at the forsterite surface in a predominately bidentate fashion at adsorbed H2O concentrations below 27 µmol/m2. Above this concentration and up to 76 µmol/m2, monodentate coordinated complexes become dominant. Beyond a threshold adsorbed H2O concentration of 76 µmol/m2, crystalline carbonates continuously precipitate as magnesite, and the particles that form are hundreds of times larger than the estimated thicknesses of the adsorbed water films of about 7 to 15 Å. At an applied level, these results suggest that mineral carbonation in scCO2 dominated fluids near the wellbore and adjacent to caprocks will be insignificant and limited to surface complexation, unless adsorbed H2O concentrations are high enough to promote crystalline carbonate formation. At a fundamental level, the surface complexes and their dependence on adsorbed H2O concentration give insights regarding forsterite dissolution processes and magnesite nucleation and growth.

  18. Evidence for Carbonate Surface Complexation during Forsterite Carbonation in Wet Supercritical Carbon Dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Loring, John S.; Chen, Jeffrey; Benezeth, Pascale; Qafoku, Odeta; Ilton, Eugene S.; Washton, Nancy M.; Thompson, Christopher J.; Martin, Paul F.; McGrail, B. Peter; Rosso, Kevin M.; Felmy, Andrew R.; Schaef, Herbert T.

    2015-06-16

    Continental flood basalts are attractive formations for geologic sequestration of carbon dioxide because of their reactive divalent-cation containing silicates, such as forsterite (Mg2SiO4), suitable for long-term trapping of CO2 mineralized as metal carbonates. The goal of this study was to investigate at a molecular level the carbonation products formed during the reaction of forsterite with supercritical CO2 (scCO2) as a function of the concentration of H2O adsorbed to the forsterite surface. Experiments were performed at 50 °C and 90 bar using an in situ IR titration capability, and post-reaction samples were examined by ex situ techniques, including SEM, XPS, FIB-TEM, TGA-MS, and MAS-NMR. Carbonation products and reaction extents varied greatly with adsorbed H2O. We show for the first time evidence of Mg-carbonate surface complexation under wet scCO2 conditions. Carbonate is found to be coordinated to Mg at the forsterite surface in a predominately bidentate fashion at adsorbed H2O concentrations below 27 µmol/m2. Above this concentration and up to 76 µmol/m2, monodentate coordinated complexes become dominant. Beyond a threshold adsorbed H2O concentration of 76 µmol/m2, crystalline carbonates continuously precipitate as magnesite, and the particles that form are hundreds of times larger than the estimated thicknesses of the adsorbed water films of about 7 to 15 Å. At an applied level, the implication of these results is that mineral trapping in scCO2 dominated fluids will be insignificant and limited to surface complexation unless adsorbed H2O concentrations are high enough to promote crystalline carbonate formation. At a fundamental level, the surface complexes and their dependence on adsorbed H2O concentration give insights regarding forsterite dissolution processes and magnesite nucleation and growth.

  19. Probing the orientations of coordination complex molecules onto the surface of ZnO nanoparticles by means of surface enhanced Raman scattering, UV–vis and DFT methods

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, Om; Gautam, Priyanka; Singh, Ranjan K., E-mail: ranjanksingh65@rediffmail.com

    2015-09-15

    Graphical abstract: - Highlights: • The adsorption geometry of three complex molecules onto the surface of ZnO nanoparticles is investigated by Raman, SERS and UV–vis techniques. • All the three complex molecules are adsorbed in flat-on geometry. • On the adsorption onto the ZnO NPs, the fluorescence background of Raman spectra of Zn complex is quenched. - Abstract: The surface enhanced Raman scattering (SERS) is a highly surface sensitive technique to study inter-surface properties of biological, organic, and inorganic materials. It is a precise technique to determine the adsorption geometry/orientation of the molecules as the intensity enhancement of the SERS bands depends on the adsorption geometry/orientation of molecules on SERS substrate. In the present work, Ni, Cu and Zn complexes of (Z)-N′(1,3,4-thiadiazol-2-yl) acetimidate were synthesized and adsorbed on ZnO nanoparticles. The surface enhanced Raman scattering (SERS), UV–vis and DFT techniques were applied to investigate the possible adsorption geometries of the complexes on ZnO. Consequently, it was found that the orientation of all three complex molecules is flat-on onto the surface of ZnO nanoparticles. The fluorescence background of Raman spectra of Zn complex is quenched and its geometry is isomerized after the adsorption onto the surface of ZnO nanoparticles. The adsorbed Cu complex on ZnO NPs absorbed UV radiations efficiently.

  20. Surface Structures Formed by a Copper(II Complex of Alkyl-Derivatized Indigo

    Directory of Open Access Journals (Sweden)

    Akinori Honda

    2016-10-01

    Full Text Available Assembled structures of dyes have great influence on their coloring function. For example, metal ions added in the dyeing process are known to prevent fading of color. Thus, we have investigated the influence of an addition of copper(II ion on the surface structure of alkyl-derivatized indigo. Scanning tunneling microscope (STM analysis revealed that the copper(II complexes of indigo formed orderly lamellar structures on a HOPG substrate. These lamellar structures of the complexes are found to be more stable than those of alkyl-derivatized indigos alone. Furthermore, 2D chirality was observed.

  1. Grafting of functionalized [Fe(III)(salten)] complexes to Au(111) surfaces via thiolate groups: surface spectroscopic characterization and comparison of different linker designs.

    Science.gov (United States)

    Jacob, Hanne; Kathirvel, Ketheeswari; Petersen, Finn; Strunskus, Thomas; Bannwarth, Alexander; Meyer, Sven; Tuczek, Felix

    2013-07-01

    Functionalization of surfaces with spin crossover complexes is an intensively studied topic. Starting from dinuclear iron(III)-salten complexes [Fe(salten)(pyS)]2(BPh4)2 and [Fe(thiotolylsalten)(NCS)]2 with disulfide-containing bridging ligands, corresponding mononuclear complexes [Fe(salten)(pyS)](+) and [Fe(thiotolylsalten)(NCS)] are covalently attached to Au(111) surfaces (pySH, pyridinethiol; salten, bis(3-salicylidene-aminopropyl)amine). The adsorbed monolayers are investigated by infrared reflection absorption spectroscopy (IRRAS) in combination with X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS). Comparison of the surface vibrational spectra with bulk data allows us to draw conclusions with respect to the geometry of the adsorbed complexes. An anomaly is observed in the spectra of the surface-adsorbed monolayer of [Fe(salten)(pyS)](+), which suggests that the salten ligand is partially decoordinated from the Fe(III) center and one of its phenolate arms binds to the Au(111) surface. For complex [Fe(thiotolylsalten)(NCS)] that is bound to the Au(111) surface via a thiolate-functionalized salten ligand, this anomaly is not observed, which indicates that the coordination sphere of the complex in the bulk is retained on the surface. The implications of these results with respect to the preparation of surface-adsorbed monolayers of functional transition-metal complexes are discussed.

  2. Surface complexation modeling calculation of Pb(II) adsorption onto the calcined diatomite

    Science.gov (United States)

    Ma, Shu-Cui; Zhang, Ji-Lin; Sun, De-Hui; Liu, Gui-Xia

    2015-12-01

    Removal of noxious heavy metal ions (e.g. Pb(II)) by surface adsorption of minerals (e.g. diatomite) is an important means in the environmental aqueous pollution control. Thus, it is very essential to understand the surface adsorptive behavior and mechanism. In this work, the Pb(II) apparent surface complexation reaction equilibrium constants on the calcined diatomite and distributions of Pb(II) surface species were investigated through modeling calculations of Pb(II) based on diffuse double layer model (DLM) with three amphoteric sites. Batch experiments were used to study the adsorption of Pb(II) onto the calcined diatomite as a function of pH (3.0-7.0) and different ionic strengths (0.05 and 0.1 mol L-1 NaCl) under ambient atmosphere. Adsorption of Pb(II) can be well described by Freundlich isotherm models. The apparent surface complexation equilibrium constants (log K) were obtained by fitting the batch experimental data using the PEST 13.0 together with PHREEQC 3.1.2 codes and there is good agreement between measured and predicted data. Distribution of Pb(II) surface species on the diatomite calculated by PHREEQC 3.1.2 program indicates that the impurity cations (e.g. Al3+, Fe3+, etc.) in the diatomite play a leading role in the Pb(II) adsorption and dominant formation of complexes and additional electrostatic interaction are the main adsorption mechanism of Pb(II) on the diatomite under weak acidic conditions.

  3. Modeling the surface tension of complex, reactive organic-inorganic mixtures

    Science.gov (United States)

    Schwier, A. N.; Viglione, G. A.; Li, Z.; McNeill, V. Faye

    2013-11-01

    Atmospheric aerosols can contain thousands of organic compounds which impact aerosol surface tension, affecting aerosol properties such as heterogeneous reactivity, ice nucleation, and cloud droplet formation. We present new experimental data for the surface tension of complex, reactive organic-inorganic aqueous mixtures mimicking tropospheric aerosols. Each solution contained 2-6 organic compounds, including methylglyoxal, glyoxal, formaldehyde, acetaldehyde, oxalic acid, succinic acid, leucine, alanine, glycine, and serine, with and without ammonium sulfate. We test two semi-empirical surface tension models and find that most reactive, complex, aqueous organic mixtures which do not contain salt are well described by a weighted Szyszkowski-Langmuir (S-L) model which was first presented by Henning et al. (2005). Two approaches for modeling the effects of salt were tested: (1) the Tuckermann approach (an extension of the Henning model with an additional explicit salt term), and (2) a new implicit method proposed here which employs experimental surface tension data obtained for each organic species in the presence of salt used with the Henning model. We recommend the use of method (2) for surface tension modeling of aerosol systems because the Henning model (using data obtained from organic-inorganic systems) and Tuckermann approach provide similar modeling results and goodness-of-fit (χ2) values, yet the Henning model is a simpler and more physical approach to modeling the effects of salt, requiring less empirically determined parameters.

  4. Modeling the surface tension of complex, reactive organic-inorganic mixtures

    Directory of Open Access Journals (Sweden)

    A. N. Schwier

    2013-01-01

    Full Text Available Atmospheric aerosols can contain thousands of organic compounds which impact aerosol surface tension, affecting aerosol properties such as cloud condensation nuclei (CCN ability. We present new experimental data for the surface tension of complex, reactive organic-inorganic aqueous mixtures mimicking tropospheric aerosols. Each solution contained 2–6 organic compounds, including methylglyoxal, glyoxal, formaldehyde, acetaldehyde, oxalic acid, succinic acid, leucine, alanine, glycine, and serine, with and without ammonium sulfate. We test two surface tension models and find that most reactive, complex, aqueous organic mixtures which do not contain salt are well-described by a weighted Szyszkowski–Langmuir (S–L model which was first presented by Henning et al. (2005. Two approaches for modeling the effects of salt were tested: (1 the Tuckermann approach (an extension of the Henning model with an additional explicit salt term, and (2 a new implicit method proposed here which employs experimental surface tension data obtained for each organic species in the presence of salt used with the Henning model. We recommend the use of method (2 for surface tension modeling because the Henning model (using data obtained from organic-inorganic systems and Tuckermann approach provide similar modeling fits and goodness of fit (χ2 values, yet the Henning model is a simpler and more physical approach to modeling the effects of salt, requiring less empirically determined parameters.

  5. DFT calculations of magnetic parameters for molybdenum complexes and hydroxymethyl intermediates trapped on silica surface

    Science.gov (United States)

    Sojka, Zbigniew; Pietrzyk, Piotr

    2006-03-01

    Density functional theory (DFT) calculations of EPR parameters and their structure sensitivity for selected surface paramagnetic species involved in oxidative dehydrogenation of methanol over silica grafted molybdenum catalyst were investigated. Two surface complexes, Mo 4 c/SiO 2 and {O -sbnd Mo 4 c}/SiO 2, as well as rad CH 2OH radical trapped on the SiO 2 matrix were taken as the examples. The spin-restricted zeroth order regular approximation (ZORA) implemented in the Amsterdam Density Functional suite was used to calculate the electronic g tensor for those species. The predicted values were in satisfactory agreement with experimental EPR results. Five different coordination modes of the rad CH 2OH radical on the silica surface were considered and the isotropic 13C, 17O, and 1H hyperfine coupling constants (HFCC) of the resultant surface complexes were calculated. Structure sensitivity of the HFCC values was discussed in terms of the angular deformations caused by hydrogen bonding with the silica surface.

  6. Tailored optical vector fields for ultrashort-pulse laser induced complex surface plasmon structuring.

    Science.gov (United States)

    Ouyang, J; Perrie, W; Allegre, O J; Heil, T; Jin, Y; Fearon, E; Eckford, D; Edwardson, S P; Dearden, G

    2015-05-18

    Precise tailoring of optical vector beams is demonstrated, shaping their focal electric fields and used to create complex laser micro-patterning on a metal surface. A Spatial Light Modulator (SLM) and a micro-structured S-waveplate were integrated with a picosecond laser system and employed to structure the vector fields into radial and azimuthal polarizations with and without a vortex phase wavefront as well as superposition states. Imprinting Laser Induced Periodic Surface Structures (LIPSS) elucidates the detailed vector fields around the focal region. In addition to clear azimuthal and radial plasmon surface structures, unique, variable logarithmic spiral micro-structures with a pitch Λ ∼1μm, not observed previously, were imprinted on the surface, confirming unambiguously the complex 2D focal electric fields. We show clearly also how the Orbital Angular Momentum(OAM) associated with a helical wavefront induces rotation of vector fields along the optic axis of a focusing lens and confirmed by the observed surface micro-structures.

  7. Complex polymer brush gradients based on nanolithography and surface-initiated polymerization.

    Science.gov (United States)

    Lin, Xiankun; He, Qiang; Li, Junbai

    2012-05-07

    Confined surface gradients consisting of polymer brushes have great potential in various applications such as microfluidic devices, sensors, and biophysical research. Among the available fabrication approaches, nanolithographies combined with self-assembled monolayers and surface-initiated polymerization have became powerful tools to engineer confined gradients or predefined complex gradients on the nanometre size. In this tutorial review, we mainly highlight the research progress of the fabrication of confined polymer brush gradients by using electron beam, laser, and probe-based nanolithographies and the physical base for these approaches. The application of these polymer brush gradients in biomedical research is also addressed.

  8. Spectroscopic study on uranyl carboxylate complexes formed at the surface layer of Sulfolobus acidocaldarius.

    Science.gov (United States)

    Reitz, Thomas; Rossberg, Andre; Barkleit, Astrid; Steudtner, Robin; Selenska-Pobell, Sonja; Merroun, Mohamed L

    2015-02-14

    The complexation of U(vi) at the proteinaceous surface layer (S-layer) of the archaeal strain Sulfolobus acidocaldarius was investigated over a pH range from pH 1.5 to 6 at the molecular scale using time-resolved laser-induced fluorescence spectroscopy (TRLFS) and U L(III)-edge extended X-ray absorption fine structure (EXAFS). The S-layer, which represents the interface between the cell and its environment, is very stable against high temperatures, proteases, and detergents. This allowed the isolation and purification of S-layer ghosts (= empty cells) that maintain the size and shape of the cells. In contrast to many other microbial cell envelope compounds the studied S-layer is not phosphorylated, enabling the investigation of uranyl carboxylate complexes formed at microbial surfaces. The latter are usually masked by preferentially formed uranyl phosphate complexes. We demonstrated that at highly acidic conditions (pH 1.5 to 3) no uranium was bound by the S-layer. In contrast to that, at moderate acidic pH conditions (pH 4.5 and 6) a complexation of U(vi) at the S-layer via deprotonated carboxylic groups was stimulated. Titration studies revealed dissociation constants for the carboxylic groups of glutamic and aspartic acid residues of pK(a) = 4.78 and 6.31. The uranyl carboxylate complexes formed at the S-layer did not show luminescence properties at room temperature, but only under cryogenic conditions. The obtained luminescence maxima are similar to those of uranyl acetate. EXAFS spectroscopy demonstrated that U(vi) in these complexes is mainly coordinated to carboxylate groups in a bidentate binding mode. The elucidation of the molecular structure of these complexes was facilitated by the absence of phosphate groups in the studied S-layer protein.

  9. Modeling the Effect of Dissolved Hydrogen Sulfide on Mg2+-water Complex on Dolomite {104} Surfaces

    CERN Document Server

    Shen, Zhizhang; Brown, Philip E; Szlufarska, Izabela; Xu, Huifang

    2016-01-01

    The key kinetic barrier to dolomite formation is related to the surface Mg2+-H2O complex, which hinders binding of surface Mg2+ ions to the CO3 2- ions in solution. It has been proposed that this reaction can be catalyzed by dissolved hydrogen sulfide. To characterize the role of dissolved hydrogen sulfide in the dehydration of surface Mg 2+ ions, ab initio simulations based on density functional theory (DFT) were carried out to study the thermodynamics of competitive adsorption of hydrogen sulfide and water on dolomite (104) surfaces from solution. We find that water is thermodynamically more stable on the surface with the difference in adsorption energy of -13.6 kJ/mol (in vacuum) and -12.8 kJ/mol (in aqueous solution). However, aqueous hydrogen sulfide adsorbed on the surface increases the Mg2+-H2O distances on surrounding surface sites. Two possible mechanisms were proposed for the catalytic effects of adsorbed hydrogen sulfide on the anhydrous Ca-Mg-carbonate crystallization at low temperature.

  10. COMPLEX SURFACE RECONSTRUCTION BASED ON OBJECT-ORIENTED DEVELOPING TOOL VBA

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Taking AutoCAD2000 as platform, an algorithm for the reconstruction of surface from scattered data points based on VBA is presented. With this core technology customers can be free from traditional AutoCAD as an electronic board and begin to create actual presentation of real-world objects. VBA is not only a very powerful tool of development, but with very simple syntax. Associating with those solids, objects and commands of AutoCAD 2000, VBA notably simplifies previous complex algorithms, graphical presentations and processing, etc. Meanwhile, it can avoid appearance of complex data structure and data format in reverse design with other modeling software. Applying VBA to reverse engineering can greatly improve modeling efficiency and facilitate surface reconstruction.

  11. Retrieving the size of particles with rough and complex surfaces from two-dimensional scattering patterns

    Science.gov (United States)

    Ulanowski, Z.; Hirst, E.; Kaye, P. H.; Greenaway, R.

    2012-12-01

    Scattered intensity measurement is a commonly used method for determining the size of small particles. However, it requires calibration and is subject to errors due to changes in incident irradiance or detector sensitivity. Analysis of two-dimensional scattering patterns offers an alternative approach. We test morphological image processing operations on patterns from a diverse range of particles with rough surfaces and/or complex structure, including mineral dust, spores, pollen, ice analogs and sphere clusters from 4 to 88 μm in size. It is found that the median surface area of intensity peaks is the most robust measure, and it is inversely proportional to particle size. The trend holds well for most particle types, as long as substantial roughness or complexity is present. One important application of this technique is the sizing of atmospheric particles, such as ice crystals.

  12. Sub-monolayer film growth of a volatile lanthanide complex on metallic surfaces

    Science.gov (United States)

    Chen, Jinjie; Edelmann, Kevin; Wulfhekel, Wulf

    2015-01-01

    Summary We deposited a volatile lanthanide complex, tris(2,2,6,6-tetramethyl-3,5-heptanedionato)terbium(III), onto metal surfaces of Cu(111), Ag(111) and Au(111) in vacuum and observed well-ordered sub-monolayer films with low temperature (5 K) scanning tunneling microscopy. The films show a distorted three-fold symmetry with a commensurate structure. Scanning tunneling spectroscopy reveals molecular orbitals delocalized on the ligands of the molecule. Our results imply that this complex can be transferred onto the metal substrates without molecular decomposition or contamination of the surface. This new rare-earth-based class of molecules broadens the choice of molecular magnets to study with scanning tunneling microscopy. PMID:26733215

  13. Sub-monolayer film growth of a volatile lanthanide complex on metallic surfaces

    Directory of Open Access Journals (Sweden)

    Hironari Isshiki

    2015-12-01

    Full Text Available We deposited a volatile lanthanide complex, tris(2,2,6,6-tetramethyl-3,5-heptanedionatoterbium(III, onto metal surfaces of Cu(111, Ag(111 and Au(111 in vacuum and observed well-ordered sub-monolayer films with low temperature (5 K scanning tunneling microscopy. The films show a distorted three-fold symmetry with a commensurate structure. Scanning tunneling spectroscopy reveals molecular orbitals delocalized on the ligands of the molecule. Our results imply that this complex can be transferred onto the metal substrates without molecular decomposition or contamination of the surface. This new rare-earth-based class of molecules broadens the choice of molecular magnets to study with scanning tunneling microscopy.

  14. Effect of glutamic acid on copper sorption onto kaolinite. Batch experiments and surface complexation modeling

    Energy Technology Data Exchange (ETDEWEB)

    Karimzadeh, Lotfallah; Barthen, Robert; Gruendig, Marion; Franke, Karsten; Lippmann-Pipke, Johanna [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Reactive Transport; Stockmann, Madlen [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes

    2017-06-01

    In this work, we study the mobility behavior of Cu(II) under conditions related to an alternative, neutrophile biohydrometallurgical Cu(II) leaching approach. Sorption of copper onto kaolinite influenced by glutamic acid (Glu) was investigated in the presence of 0.01 M NaClO{sub 4} by means of binary and ternary batch adsorption measurements over a pH range of 4 to 9 and surface complexation modeling.

  15. Polyelectrolyte complexes : Preparation, characterization, and use for control of wet and dry adhesion between surfaces

    OpenAIRE

    Ankerfors, Caroline

    2012-01-01

    This thesis examines polyelectrolyte complex (PEC) preparation, adsorption behaviour, and potential use for control of wet and dry adhesion between surfaces. PEC formation was studied using a jet-mixing method not previously used for mixing polyelectrolytes. The PECs were formed using various mixing times, and the results were compared with those for PECs formed using the conventional polyelectrolyte titration method. The results indicated that using the jet mixer allowed the size of the form...

  16. Surface Complexation Modeling in Variable Charge Soils: Prediction of Cadmium Adsorption

    OpenAIRE

    Giuliano Marchi; Cesar Crispim Vilar; George O’Connor; Letuzia Maria de Oliveira; Adriana Reatto; Thomaz Adolph Rein

    2015-01-01

    ABSTRACT Intrinsic equilibrium constants for 22 representative Brazilian Oxisols were estimated from a cadmium adsorption experiment. Equilibrium constants were fitted to two surface complexation models: diffuse layer and constant capacitance. Intrinsic equilibrium constants were optimized by FITEQL and by hand calculation using Visual MINTEQ in sweep mode, and Excel spreadsheets. Data from both models were incorporated into Visual MINTEQ. Constants estimated by FITEQL and incorporated in Vis...

  17. Potential energy surface and rovibrational energy levels of the H2-CS van der Waals complex.

    Science.gov (United States)

    Denis-Alpizar, Otoniel; Stoecklin, Thierry; Halvick, Philippe; Dubernet, Marie-Lise; Marinakis, Sarantos

    2012-12-21

    Owing to its large dipole, astrophysicists use carbon monosulfide (CS) as a tracer of molecular gas in the interstellar medium, often in regions where H(2) is the most abundant collider. Predictions of the rovibrational energy levels of the weakly bound complex CS-H(2) (not yet observed) and also of rate coefficients for rotational transitions of CS in collision with H(2) should help to interpret the observed spectra. This paper deals with the first goal, i.e., the calculation of the rovibrational energy levels. A new four-dimensional intermolecular potential energy surface for the H(2)-CS complex is presented. Ab initio potential energy calculations were carried out at the coupled-cluster level with single and double excitations and a perturbative treatment of triple excitations, using a quadruple-zeta basis set and midbond functions. The potential energy surface was obtained by an analytic fit of the ab initio data. The equilibrium structure of the H(2)-CS complex is found to be linear with the carbon pointing toward H(2) at the intermolecular separation of 8.6 a(o). The corresponding well depth is -173 cm(-1). The potential was used to calculate the rovibrational energy levels of the para-H(2)-CS and ortho-H(2)-CS complexes. The present work provides the first theoretical predictions of these levels. The calculated dissociation energies are found to be 35.9 cm(-1) and 49.9 cm(-1), respectively, for the para and ortho complexes. The second virial coefficient for the H(2)-CS pair has also been calculated for a large range of temperature. These results could be used to assign future experimental spectra and to check the accuracy of the potential energy surface.

  18. Normal contour error measurement on-machine and compensation method for polishing complex surface by MRF

    Science.gov (United States)

    Chen, Hua; Chen, Jihong; Wang, Baorui; Zheng, Yongcheng

    2016-10-01

    The Magnetorheological finishing (MRF) process, based on the dwell time method with the constant normal spacing for flexible polishing, would bring out the normal contour error in the fine polishing complex surface such as aspheric surface. The normal contour error would change the ribbon's shape and removal characteristics of consistency for MRF. Based on continuously scanning the normal spacing between the workpiece and the finder by the laser range finder, the novel method was put forward to measure the normal contour errors while polishing complex surface on the machining track. The normal contour errors was measured dynamically, by which the workpiece's clamping precision, multi-axis machining NC program and the dynamic performance of the MRF machine were achieved for the verification and security check of the MRF process. The unit for measuring the normal contour errors of complex surface on-machine was designed. Based on the measurement unit's results as feedback to adjust the parameters of the feed forward control and the multi-axis machining, the optimized servo control method was presented to compensate the normal contour errors. The experiment for polishing 180mm × 180mm aspherical workpiece of fused silica by MRF was set up to validate the method. The results show that the normal contour error was controlled in less than 10um. And the PV value of the polished surface accuracy was improved from 0.95λ to 0.09λ under the conditions of the same process parameters. The technology in the paper has been being applied in the PKC600-Q1 MRF machine developed by the China Academe of Engineering Physics for engineering application since 2014. It is being used in the national huge optical engineering for processing the ultra-precision optical parts.

  19. New strategy for chemically attachment of Schiff base complexes on Multiwalled Carbon Nanotubes surfaces

    Directory of Open Access Journals (Sweden)

    Leila Moradi

    2014-06-01

    Full Text Available Chemically attachment of Schiff base complexes on multiwalled carbon nanotubes (MWCNTs surfaces through a convenient and simple method was studied. In the first step of this method, we present a new method for preparation of aminated MWCNTs in order to attachment of (new chlorinated salen Schiff bases. Amination of multiwalled carbon nanotubes performed under microwave (MW irradiation through a one pot two step reaction. The chemically attachment of salen Schiff bases on functionalized MWCNTs (salen@MWCNTs performed under a facile simple nucleophilic substitution reaction and complexation of attached salen Schiff bases (salen complex@MWCNTs in last step, have been occurred with reaction of transition metal salts and salen@MWCNTs. The obtained products were characterized in detail, using FTIR, XRD, UV-Vis absorption, SEM and EDX methods.

  20. Zeolite-mediated photochemical charge separation using a surface-entrapped ruthenium-polypyridyl complex.

    Science.gov (United States)

    Kim, Yanghee; Lee, Hyunjung; Dutta, Prabir K; Das, Amitava

    2003-06-30

    Employing the strategy of quaternization of the 2,2' N atoms of the conjugated bipyridine ligand 1,4-bis[2-(4'-methyl-2,2'-bipyrid-4-yl)ethenyl]benzene (L), a polypyridyl complex of ruthenium(II) was tethered on the surface of zeolite Y. Electrochemical and spectroscopic properties of the complex suggest that, upon visible photoexcitation of the MLCT band, the electron is localized on the conjugated ligand rather than the bipyridines. Electron transfer from the surface complex to bipyridinium ions (methyl viologen) within the zeolite was observed. Visible light photolysis of the ruthenium-zeolite solid ion-exchanged with diquat and suspended in a propyl viologen sulfonate solution led to permanent formation of the blue propyl viologen sulfonate radical ion in solution. The model that is proposed involves intrazeolitic charge transfer to ion-exchanged diquat followed by interfacial (zeolite to solution) electron transfer to propyl viologen sulfonate in solution. Because of the slow intramolecular back-electron-transfer reaction and the forward electron propagation via the ion-exchanged diquat, Ru(III) is formed. This Ru(III) complex formed on the zeolite is proposed to react rapidly with water in the presence of light, followed by reaction with the propyl viologen sulfonate, to form pyridones and regeneration of Ru(II), which then continues the photochemical process.

  1. Pulsed supersonic molecular beam for characterization of chemically active metal-organic complexes at surfaces

    Science.gov (United States)

    Lear, Amanda M.

    Metal-organic coordination networks (MOCNs) at surfaces consist of a complex of organic ligands bound to an atomic metal center. The MOCNs, when chosen appropriately, can form highly-ordered arrays at surfaces. Ultra-high vacuum surface studies allow control of surface composition and provide 2D growth restrictions, which lead to under-coordinated metal centers. These systems provide an opportunity to tailor the chemical function of the metal centers due to the steric restrictions imposed by the surface. Tuning the adsorption/desorption energy at a metal center and developing a cooperative environment for catalysis are the key scientific questions that motivate the construction of a molecular beam surface analysis system. Characterization of the created systems can be performed utilizing a pulsed supersonic molecular beam (PSMB) in unison with a quadrupole mass spectrometer. A PSMB allows for the highly controlled delivery of reactants with well-defined energy to a given platform making it possible to elucidate detailed chemical tuning information. In this thesis, a summary of prior theoretical molecular beam derivations is provided. Design considerations and an overview of the construction procedure for the current molecular beam apparatus, including initial characterization experiments, are presented. By impinging an Ar beam on a Ag(111) surface, the location of the specular angle (˜65°) and rough sample perimeter coordinates were determined. Additionally, surface analysis experiments, mainly Auger Electron Spectroscopy (AES), were performed to investigate the oxidation of epitaxial graphene on the SiC(0001) surface utilizing an oxygen cracking method. The AES experiments are described in detail and highlight the challenges that were faced when several different graphene samples were used for the oxygen adsorption/desorption experiments.

  2. Interpreting Ground Temperature Measurements for Thermophysical Properties on Complex Surfaces of the Moon and Mars

    Science.gov (United States)

    Vasavada, A. R.; Hamilton, V. E.; Team, M.

    2013-12-01

    With the successful deployments of the Diviner radiometer on the Lunar Reconnaissance Orbiter and the REMS ground temperature sensor on the Curiosity Mars rover, records of ground temperature with high accuracy and finely sampled diurnal and seasonal cycles have become available. The detailed shapes of these temperature profiles allow inferences beyond just bulk thermophysical properties. Subtle (or sometime significant) effects of surface roughness, slope, and lateral and vertical heterogeneity may be identified in the surface brightness temperature data. For example, changes in thermal or physical properties with depth in the shallow subsurface affect the conduction and storage of thermal energy. These affect the surface energy balance and therefore surface temperatures, especially the rate of cooling at night. Making unique determinations of subsurface soil properties requires minimizing the uncertainties introduced by other effects. On Mars, atmospheric aerosol opacity and wind-driven sensible heat fluxes also affect the diurnal and annual temperature profiles. On both bodies, variations in thermal inertia, slopes, roughness, albedo, and emissivity within the radiometer footprint will cause the composite brightness temperature to differ from a kinetic temperature. Nevertheless, we have detected potential effects of complex surfaces in the temperature data from both Diviner and Curiosity. On the Moon, the results reveal a nearly ubiquitous surface structure, created mechanically by impact gardening, that controls the thermal response of the surface. On Mars, the thermal response is controlled primarily by grain size, cementation, lithification, and composition. However, the secondary effects of near-surface layering aid in the interpretation of stratigraphy and in the identification of geologic processes that have altered the surface.

  3. Complex interaction of subsequent surface streamers via deposited charge: a high-resolution experimental study

    Science.gov (United States)

    Hoder, T.; Synek, P.; Chorvát, D.; Ráhel', J.; Brandenburg, R.; Černák, M.

    2017-07-01

    The coplanar barrier discharge in synthetic air at 30 kPa pressure was studied by time-correlated single photon counting enhanced optical emission spectroscopy, far-field microscopy enhanced intensified CCD camera and sensitive current measurements. The discharge operated in a regime where two subsequent microdischarges appeared within the same voltage half-period. The electrical analysis of the barrier discharge setup enabled us to quantify charge transfer and the effective electric field development. During the second microdischarge the positive surface streamers follow the interface (triple-line) between the area of deposited charge from the previous one and the area of uncharged dielectric surface. It is shown that additional branching and flashes of surface streamers are responsible for the increased spatial complexity of the deposited surface charges at high overvoltage. A suppressed streamer propagating over the area of deposited surface charge was tracked and the evidence of surface streamer reconnection is presented. A spatiotemporal distribution (resolution of 120 ps and 100 μm) of the reduced electric field strength was obtained for both microdischarges from the recorded luminosities of the molecular nitrogen. The reduced electric field of positive streamers in the first microdischarge reached 1200 Td. For the second one, the electric field values for the streamer at the triple-line are slightly lower than that, while for the suppressed streamers are even higher.

  4. Synthesis in situ of gold nanoparticles by a dialkynyl Fischer carbene complex anchored to glass surfaces

    Science.gov (United States)

    Bertolino, María Candelaria; Granados, Alejandro Manuel

    2016-10-01

    In this work we present a detailed study of classic reactions such as "click reaction" and nucleophilic substitution reaction but on glass solid surface (slides). We used different reactive center of a dialkynylalcoxy Fischer carbene complex of tungsten(0) to be anchored to modified glass surface with amine, to obtain aminocarbene, and azide terminal groups. These cycloaddition reaction showed regioselectivity to internal triple bond of dialkynyl Fischer carbene complex without Cu(I) as catalyst. Anyway the carbene anchored was able to act as a reducing agent to produce in situ very stable gold nanoparticles fixed on surface. We showed the characterization of modified glasses by contact angle measurements and XPS. Synthesized nanoparticles were characterized by SEM, XPS, EDS and UV-vis. The modified glasses showed an important enhancement Raman-SERS. This simple, fast and robust method to create a polifunctional and hybrid surfaces can be valuable in a wide range of applications such as Raman-SERS substrates and other optical fields.

  5. Complex frequencies and field distributions of localized surface plasmon modes in graphene-coated subwavelength wires

    Science.gov (United States)

    Cuevas, Mauro; Riso, Máximo A.; Depine, Ricardo A.

    2016-04-01

    In this work we study the modal characteristics of localized surface plasmons in graphene-coated, circular cross-section wires. Localized surface plasmons are represented in terms of cylindrical multipole partial waves characterized by discrete, complex frequencies that depend on the size of the wire and can be dynamically tuned via a gate voltage. We consider both intrinsically nonplasmonic wires and intrinsically plasmonic wires. In the first case the localized surface plasmons are introduced by the graphene coating, whereas in the second case the localized eigenmodes of the graphene coating are expected to hybridize those already existing in the bare wire. We show that the approach presented here, valid for particle sizes where the retardation effects can be significant, is in good agreement with analytical expressions obtained in the limit when particle size is very small compared to the wavelength of the eigenmode and with results indirectly determined from scattering cross-section spectra.

  6. Ab initio potential energy and dipole moment surfaces of the F(-)(H2O) complex.

    Science.gov (United States)

    Kamarchik, Eugene; Toffoli, Daniele; Christiansen, Ove; Bowman, Joel M

    2014-02-05

    We present full-dimensional, ab initio potential energy and dipole moment surfaces for the F(-)(H2O) complex. The potential surface is a permutationally invariant fit to 16,114 coupled-cluster single double (triple)/aVTZ energies, while the dipole surface is a covariant fit to 11,395 CCSD(T)/aVTZ dipole moments. Vibrational self-consistent field/vibrational configuration interaction (VSCF/VCI) calculations of energies and the IR-spectrum are presented both for F(-)(H2O) and for the deuterated analog, F(-)(D2O). A one-dimensional calculation of the splitting of the ground state, due to equivalent double-well global minima, is also reported.

  7. Dynamic etching of soluble surface layers with on-line inductively coupled plasma mass spectrometry detection - a novel approach for determination of complex metal oxide surface cation stoichiometry

    OpenAIRE

    Limbeck, A; Rupp, GM; M. Kubicek; Tellez, H.; Druce, J; Ishihara, T.; Kilner, JA; Fleig, J.

    2016-01-01

    In this work, an innovative approach for determining the surface stoichiometry of complex metal oxide (CMO) thin films is presented. The procedure is based on treatment of the sample surface with different etching solutions, followed by on-line analysis of the derived eluates using inductively coupled plasma ? mass spectrometry (ICP-MS). Via consecutive treatment of the sample surface with water and diluted HCl, a differentiation between water soluble and acid soluble parts of near surface re...

  8. Preparation and surface photoelectric properties of Fe(II/III) complexes

    Science.gov (United States)

    Jin, Jing; Xu, Xiao-Ting; Li, Dan; Han, Xiao; Li, Lei; Chi, Yu-Xian; Niu, Shu-Yun; Zhang, Guang-Ning

    2013-05-01

    Four Fe(II/III) supramolecules, {[Fe(Hpdc)2(H2O)2]·2H2O} (1), [Fe(HImbc)2(H2O)2] (2), [Fe(phen)2(CN)2]·CH3CH2OH·2H2O (3), K[Fe(tp)2]·SO4 (4) (H2pdc = 2,5-Pyridinedicarboxylic acid, H2Imbc = 4,5-Imidazoledicarboxylic acid, phen = 1,10-phenanthroline, tp- = poly(pyrazolyl)borate), were synthesized by hydrothermal and room temperature stirring methods. They were characterized by single crystal X-ray diffraction, surface photovoltage spectroscopy (SPS), field-induced surface photovoltage spectroscopy (FISPS), electron paramagnetic resonance (EPR), UV-Vis absorption spectra (UV-Vis), infrared spectra (IR) and element analysis. The structural analyses indicate that complex (1) is a supramolecule with 2D structure connected by hydrogen bonds. Complex (2) is a supramolecule with hydrogen-bonded 3D structure. Complexes (3) and (4) are both 1D supramolecules connected by hydrogen bonds. The electronic state of central metal Fe(II) ions in complexes (1) and (2) is d6 with FeN2O4 coordination mode, lying in weaker distorted octahedral field. The electronic state of Fe(II) ion in complex (3) is d6 with Fe(CN)2N4 mode in the strong distorted octahedral field. The electronic state of Fe(III) ion in complex (4) is d5 with FeN6 mode, lying in the strong octahedral field. The micro-environment of Fe(II/III) ions in the four complexes is further investigated by EPR. The SPS of four complexes all exhibit photovoltage responses in the range of 300-700 nm. This indicates that they all possess certain photoelectric conversion capability. The effects of component, structure, type of ligands of the complexes, valence state and coordination micro-environment of the central metal ions on the SPS were discussed. Furthermore, the SPS and UV-Vis absorption spectra were interrelated.

  9. Surface Induced Dissociation Yields Quaternary Substructure of Refractory Noncovalent Phosphorylase B and Glutamate Dehydrogenase Complexes

    Science.gov (United States)

    Ma, Xin; Zhou, Mowei; Wysocki, Vicki H.

    2014-03-01

    Ion mobility (IM) and tandem mass spectrometry (MS/MS) coupled with native MS are useful for studying noncovalent protein complexes. Collision induced dissociation (CID) is the most common MS/MS dissociation method. However, some protein complexes, including glycogen phosphorylase B kinase (PHB) and L-glutamate dehydrogenase (GDH) examined in this study, are resistant to dissociation by CID at the maximum collision energy available in the instrument. Surface induced dissociation (SID) was applied to dissociate the two refractory protein complexes. Different charge state precursor ions of the two complexes were examined by CID and SID. The PHB dimer was successfully dissociated to monomers and the GDH hexamer formed trimeric subcomplexes that are informative of its quaternary structure. The unfolding of the precursor and the percentages of the distinct products suggest that the dissociation pathways vary for different charge states. The precursors at lower charge states (+21 for PHB dimer and +27 for GDH hexamer) produce a higher percentage of folded fragments and dissociate more symmetrically than the precusors at higher charge states (+29 for PHB dimer and +39 for GDH hexamer). The precursors at lower charge state may be more native-like than the higher charge state because a higher percentage of folded fragments and a lower percentage of highly charged unfolded fragments are detected. The combination of SID and charge reduction is shown to be a powerful tool for quaternary structure analysis of refractory noncovalent protein complexes, as illustrated by the data for PHB dimer and GDH hexamer.

  10. Heterogeneous platinum-catalyzed hydrogenation of dialkyl(diolefin)platinum(II) complexes: A new route to platinum surface alkyls

    OpenAIRE

    McCarthy, Thomas J.; Shih, Yen-Shiang; Whitesides, George M.

    1981-01-01

    Platinum metal catalyzes the reduction of dialkyl(diolefin)platinum(II) complexes by dihydrogen to alkanes and platinum(0). The reaction involves adsorption of the platinum(II) complex on the platinum(0) catalyst surface with conversion of the alkyl moieties to platinum surface alkyls; these appear as alkane products. The platinum atom originally present in the soluble organoplatinum species becomes part of the platinum(0) surface.

  11. Surface structure of the Ag-In-(rare earth) complex intermetallics

    Science.gov (United States)

    Hars, S. S.; Sharma, H. R.; Smerdon, J. A.; Yadav, T. P.; Al-Mahboob, A.; Ledieu, J.; Fournée, V.; Tamura, R.; McGrath, R.

    2016-05-01

    We present a study of the surface structure of the Ag-In-RE (RE: rare-earth elements Gd, Tb, and Yb) complex intermetallics using scanning tunneling microscopy and low-energy electron diffraction. The surface of the Ag-In-Yb approximant prepared by sputter-annealing methods under ultrahigh-vacuum conditions produces a flat (100) surface with no facets. However, the Ag-In-Gd and Ag-In-Tb 1/1 approximants, which have a surface miscut of about 12∘ relative to the (100) plane, develop surface facets along various crystallographic directions. The structure of each facet can be explained as a truncation of the rhombic triacontahedral clusters, i.e., the main building blocks of these systems. Despite their differences in atomic structure, symmetry, and density, the facets show common features. The facet planes are In rich. The analysis of the nearest-neighbor atom distances suggests that In atoms form bonds with the RE atoms, which we suggest is a key factor that stabilizes even low-density facet planes.

  12. Matching a surface complexation model with ab initio molecular dynamics: montmorillonite case

    Energy Technology Data Exchange (ETDEWEB)

    Kulik, D.A.; Churakov, S.V. [Paul Scherrer Institute, Nuclear Energy and Safety Dpt., Lab. for Waste Management, CH-5232 Villigen PSI (Switzerland)

    2005-07-01

    Speciation modelling of sorption on mineral-water interfaces is performed with help of surface complexation models (SCM), suitable for diluted suspensions that seem to reach adsorption equilibrium within laboratory times. Electrostatic SCMs need several input parameters even for a relatively simple oxide mineral surface. Moreover, the electrolyte ion adsorption constants in triple layer (TL) or basic Stern (BS) models depend on the inner layer capacitance density Cl, but clear physical understanding of this parameter is missing so far. SCMs can fit acidimetric or metal titration data well at quite different combinations of input parameters, and this fact casts doubt on any interpretation of fitted parameter values in terms of microscopic physicochemical mechanisms. The problem is even deeper in SCMs for clay minerals like montmorillonite having at least two surface types: the edges exposing different (aluminol and silanol) functional groups, and the basal siloxane planes with permanent charge and ion exchange. A feasible way to overcome the caveat of SCMs is seen nowadays in relying on crystallographic data and ab initio calculations to restrict the EDL setup, species stoichiometries, and input parameter values when constructing the adsorption model. The aim of this contribution is to discuss how recent advances in sample surface characterization an d in quantum-chemistry calculations for pyrophyllite can help in putting together a multi-site-surface electrostatic SCM for montmorillonite implemented in GEM approach. The quality of macroscopic model fits is checked against the titration data. (authors)

  13. Evidence for Carbonate Surface Complexation during Forsterite Carbonation in Wet Supercritical Carbon Dioxide.

    Science.gov (United States)

    Loring, John S; Chen, Jeffrey; Bénézeth, Pascale; Qafoku, Odeta; Ilton, Eugene S; Washton, Nancy M; Thompson, Christopher J; Martin, Paul F; McGrail, B Peter; Rosso, Kevin M; Felmy, Andrew R; Schaef, Herbert T

    2015-07-14

    Continental flood basalts are attractive formations for geologic sequestration of carbon dioxide because of their reactive divalent-cation containing silicates, such as forsterite (Mg2SiO4), suitable for long-term trapping of CO2 mineralized as metal carbonates. The goal of this study was to investigate at a molecular level the carbonation products formed during the reaction of forsterite with supercritical CO2 (scCO2) as a function of the concentration of H2O adsorbed to the forsterite surface. Experiments were performed at 50 °C and 90 bar using an in situ IR titration capability, and postreaction samples were examined by ex situ techniques, including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), focused ion beam transmission electron microscopy (FIB-TEM), thermal gravimetric analysis mass spectrometry (TGA-MS), and magic angle spinning nuclear magnetic resonance (MAS NMR). Carbonation products and reaction extents varied greatly with adsorbed H2O. We show for the first time evidence of Mg-carbonate surface complexation under wet scCO2 conditions. Carbonate is found to be coordinated to Mg at the forsterite surface in a predominately bidentate fashion at adsorbed H2O concentrations below 27 μmol/m(2). Above this concentration and up to 76 μmol/m(2), monodentate coordinated complexes become dominant. Beyond a threshold adsorbed H2O concentration of 76 μmol/m(2), crystalline carbonates continuously precipitate as magnesite, and the particles that form are hundreds of times larger than the estimated thicknesses of the adsorbed water films of about 7 to 15 Å. At an applied level, these results suggest that mineral carbonation in scCO2 dominated fluids near the wellbore and adjacent to caprocks will be insignificant and limited to surface complexation, unless adsorbed H2O concentrations are high enough to promote crystalline carbonate formation. At a fundamental level, the surface complexes and their dependence on adsorbed H2O

  14. Robotic path planning for non-destructive testing of complex shaped surfaces

    Science.gov (United States)

    Mineo, Carmelo; Pierce, Stephen Gareth; Wright, Ben; Nicholson, Pascual Ian; Cooper, Ian

    2015-03-01

    The requirement to increase inspection speeds for non-destructive testing (NDT) of composite aerospace parts is common to many manufacturers. The prevalence of complex curved surfaces in the industry provides significant motivation for the use of 6 axis robots for deployment of NDT probes in these inspections. A new system for robot deployed ultrasonic inspection of composite aerospace components is presented. The key novelty of the approach is through the accommodation of flexible robotic trajectory planning, coordinated with the NDT data acquisition. Using a flexible approach in MATLAB, the authors have developed a high level custom toolbox that utilizes external control of an industrial 6 axis manipulator to achieve complex path planning and provide synchronization of the employed ultrasonic phase array inspection system. The developed software maintains a high level approach to the robot programming, in order to ease the programming complexity for an NDT inspection operator. Crucially the approach provides a pathway for a conditional programming approach and the capability for multiple robot control (a significant limitation in many current off-line programming applications). Ultrasonic and experimental data has been collected for the validation of the inspection technique. The path trajectory generation for a large, curved carbon-fiber-reinforced polymer (CFRP) aerofoil component has been proven and is presented. The path error relative to a raster-scan tool-path, suitable for ultrasonic phased array inspection, has been measured to be within + 2mm over the 1.6 m2 area of the component surface.

  15. Electrochemical Instability of Phosphonate-Derivatized, Ruthenium(III) Polypyridyl Complexes on Metal Oxide Surfaces.

    Science.gov (United States)

    Hyde, Jacob T; Hanson, Kenneth; Vannucci, Aaron K; Lapides, Alexander M; Alibabaei, Leila; Norris, Michael R; Meyer, Thomas J; Harrison, Daniel P

    2015-05-13

    The oxidative stability of the molecular components of dye-sensitized photoelectrosynthesis cells for solar water splitting remains to be explored systematically. We report here the results of an electrochemical study on the oxidative stability of ruthenium(II) polypyridyl complexes surface-bound to fluorine-doped tin oxide electrodes in acidic solutions and, to a lesser extent, as a function of pH and solvent with electrochemical monitoring. Desorption occurs for the Ru(II) forms of the surface-bound complexes with oxidation to Ru(III) enhancing both desorption and decomposition. Based on the results of long-term potential hold experiments with cyclic voltammetry monitoring, electrochemical oxidation to Ru(III) results in slow decomposition of the complex by 2,2'-bipyridine ligand loss and aquation and/or anation. A similar pattern of ligand loss was also observed for a known chromophore-catalyst assembly for both electrochemical water oxidation and photoelectrochemical water splitting. Our results are significant in identifying the importance of enhancing chromophore stability, or at least transient stability, in oxidized forms in order to achieve stable performance in aqueous environments in photoelectrochemical devices.

  16. Donor-Acceptor Properties of a Single-Molecule Altered by On-Surface Complex Formation.

    Science.gov (United States)

    Meier, Tobias; Pawlak, Rémy; Kawai, Shigeki; Geng, Yan; Liu, Xunshan; Decurtins, Silvio; Hapala, Prokop; Baratoff, Alexis; Liu, Shi-Xia; Jelínek, Pavel; Meyer, Ernst; Glatzel, Thilo

    2017-08-22

    Electron donor-acceptor molecules are of outstanding interest in molecular electronics and organic solar cells for their intramolecular charge transfer controlled via electrical or optical excitation. The preservation of their electronic character in the ground state upon adsorption on a surface is cardinal for their implementation in such single-molecule devices. Here, we investigate by atomic force microscopy and scanning tunneling microscopy a prototypical system consisting of a π-conjugated tetrathiafulvalene-fused dipyridophenazine molecule adsorbed on thin NaCl films on Cu(111). Depending on the adsorption site, the molecule is found either in a nearly undisturbed free state or in a bound state. In the latter case, the molecule adopts a specific adsorption site, leading to the formation of a chelate complex with a single Na(+) alkali cation pulled out from the insulating film. Although expected to be electronically decoupled, the charge distribution of the complex is drastically modified, leading to the loss of the intrinsic donor-acceptor character. The chelate complex formation is reversible with respect to lateral manipulations, enabling tunable donor-acceptor molecular switches activated by on-surface coordination.

  17. Surface complexation modeling of the effects of phosphate on uranium(VI) adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Romero-Gonzalez, M.R.; Cheng, T.; Barnett, M.O. [Auburn Univ., AL (United States). Dept. of Civil Engeneering; Roden, E.E. [Wisconsin Univ., Madison, WI (United States). Dept. of Geology and Geophysics

    2007-07-01

    Previous published data for the adsorption of U(VI) and/or phosphate onto amorphous Fe(III) oxides (hydrous ferric oxide, HFO) and crystalline Fe(III) oxides (goethite) was examined. These data were then used to test the ability of a commonly-used surface complexation model (SCM) to describe the adsorption of U(VI) and phosphate onto pure amorphous and crystalline Fe(III) oxides and synthetic goethite-coated sand, a surrogate for a natural Fe(III)-coated material, using the component additivity (CA) approach. Our modeling results show that this model was able to describe U(VI) adsorption onto both amorphous and crystalline Fe(III) oxides and also goethite-coated sand quite well in the absence of phosphate. However, because phosphate adsorption exhibits a stronger dependence on Fe(III) oxide type than U(VI) adsorption, we could not use this model to consistently describe phosphate adsorption onto both amorphous and crystalline Fe(III) oxides and goethite-coated sand. However, the effects of phosphate on U(VI) adsorption could be incorporated into the model to describe U(VI) adsorption to both amorphous and crystalline Fe(III) oxides and goethite-coated sand, at least for an initial approximation. These results illustrate both the potential and limitations of using surface complexation models developed from pure systems to describe metal/radionuclide adsorption under more complex conditions. (orig.)

  18. Three-dimensional pose estimation model for object with complex surface

    Directory of Open Access Journals (Sweden)

    Ronghua Li

    2015-02-01

    Full Text Available The proposed three-dimensional pose estimation model for object with complex surface, which primarily absorbs the essence of scale-invariant feature transform and iterative closest point algorithm, includes two steps, off-line and online. At first, two kinds of feature databases are established in the off-line operations. Then, the online process mainly has three steps. The first one is two-dimensional edge extraction from red–green–blue (RGB information based on scale-invariant feature transform algorithm. The second one is three-dimensional surface reconstruction from the previous two-dimensional edge and the depth information obtained from depth camera. The last one is three-dimensional pose estimation based on camera calibration and iterative closest point algorithm. The Kinect camera is selected as the information acquisition device which can produce red–green–blue information and depth information. In the experiment, the container twist-lock with complex surface is taken as the object. The result shows that the accuracy of the proposed model is very high.

  19. Nanostructural Formation of Pd-Co Bimetallic Complex on HOPG Surfaces: XPS and AFM Studies

    Directory of Open Access Journals (Sweden)

    Lisandra Arroyo-Ramírez

    2009-01-01

    Full Text Available A new single source approach was developed to synthesize Pd-Co nanoparticles using a bimetallic compound, [Et3NH]2[CoPd2(μ-4-I-3,5-Me2pz4Cl4] (CoPd2, as a molecular precursor to obtain dispersed catalyst on highly ordered pyrolytic graphite (HOPG surface, in view of preparing oxygen reduction catalysts for low temperature fuel cells. X-ray photoelectron spectroscopy (XPS and atomic force microscopy (AFM techniques were employed to characterize the nanostructure formations and to determine the composition and morphology of the complex on the HOPG. Results of high resolution XPS analysis (HR-XPS revealed the binding energies corresponding to the atomic constituents of the precursor. When the precursor solution was placed on the surface of the HOPG, the bimetallic complex assumes a tubular structure and it appears that the surface of the HOPG offers a ground for the self-organization of nanostructural formations.

  20. Computational analysis of contact forces influence on cold forming processes in the dies with complex surfaces

    Science.gov (United States)

    Dragnea, D.; Lixandru, P.; Chereches, T.; Velicu, St.

    2016-08-01

    Interaction forces between the workpiece and the die appear during the cold forming process of metals in dies. Surface forces of high-intensity influence the mesh structure and internal structure of the finished piece by mechanical action. Frictional forces hinder the flow of the material in contact with the die walls, especially on surfaces of complex shape. Under certain conditions, the material can adhere to the wall of the die, leading to the blocking of the cold forming process. In order to highlight the influence of contact forces on cold forming processes in dies with complex surfaces there were used numerical simulation methods with finite elements. Numerical simulations of the process of axial cold forming in the die were carried out for analysis data acquisition necessary, in order to achieve HTD pulleys, for an ordinary range of friction coefficients. The analysis was directed to the gearing area of the HTD pulleys (head, flank and base of the tooth). The analysis highlighted the negative effects of friction forces on the shape and quality of the products and the need to use quality lubricants. Also, using the cold forming process they can be achieved substantial savings by redistribution of the material without removing it.

  1. Functionalized granular activated carbon and surface complexation with chromates and bi-chromates in wastewater.

    Science.gov (United States)

    Singha, Somdutta; Sarkar, Ujjaini; Luharuka, Pallavi

    2013-03-01

    Cr(VI) is present in the aqueous medium as chromate (CrO4(2-)) and bi-chromate (HCrO4(-)). Functionalized granular activated carbons (FACs) are used as adsorbents in the treatment of wastewaters containing hexavalent chromium. The FACs are prepared by chemical modifications of granular activated carbons (GACs) using functionalizing agents like HNO3, HCl and HF. The Brunauer, Emmett and Teller surface areas of FAC-HCl (693.5m(2)/g), FAC-HNO3 (648.8m(2)/g) and FAC-HF (726.2m(2)/g) are comparable to the GAC (777.7m(2)/g). But, the adsorption capacity of each of the FAC-HNO3, FAC-HCl and FAC-HF is found to be higher than the GAC. The functional groups play an important role in the adsorption process and pH has practically no role in this specific case. The FACs have hydrophilic protonated external surfaces in particular, along with the functional surface sites capable to make complexes with the CrO4(2-) and HCrO4(-) present. Surface complex formation is maximized in the order FAC-HNO3>FAC-HF>FAC-HCl, in proportion to the total surface acidity. This is also confirmed by the well-known pseudo second-order kinetic model. Physi-sorption equilibrium isotherms are parameterized by using standard Freundlich and Langmuir models. Langmuir fits better. The formation of surface complexes with the functional groups and hexavalent chromium is also revealed in the images of field emission scanning electron micrograph; energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy analysis after adsorption. The intra-particle diffusion is not the only rate-controlling factor. The Boyd's film diffusion model fits very well with R(2) as high as 98.1% for FAC-HNO3. This result demonstrates that the functionalization of the GAC by acid treatments would increase the diffusion rate, predominantly with a boundary layer diffusion effect. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Complex Boronized Layer on the Hot-dip Aluminized Steels and Its Surface Performances

    Institute of Scientific and Technical Information of China (English)

    LUOXin-min; LIDian-kai; WANGLan; CHENKang-min

    2004-01-01

    Plain carbon steels were dipped in molten aluminum bath at 720℃±5℃ and diffused for 1.2.5 and 6 hours respectively and then horonized at 950℃ for 6 hours. The oxidation, hot-corrosion and abrasion resistance behavior were examined. The experimental results showed the compounds of the aluminized layer, from the surface to the matrix, were composed of Fe2Al5(η-phase/.Fe3Al(β1-phase)and α phase. The microstructure of aluminized plus complex boronized were similar to that simplex boronized. The XRD analysis results indicated that there existed Fe.B. Fe2AlB2 and Fe2Al5 in this kind of layer, The simplex aluminized layers still remained bright gray appearance when oxidized at 950℃, but complex horonized layer was not able to resist oxidization at the temperature. Both the layers of complex botanized and aluminized had the same anti-oxidizatian level in the circulative oxidization tesfs, and also good anti-corrosion abilily in molten salt medium. Under dry abrasive conditions, wear resistance of complex botanized layer was superior to the aluminized layer.

  3. Complex Boronized Layer on the Hot-dip Aluminized Steels and Its Surface Performances

    Institute of Scientific and Technical Information of China (English)

    LUO Xin-min; LI Dian-kai; WANG Lan; CHEN Kang-min

    2004-01-01

    Plain carbon steels were dipped in molten aluminum bath at 720℃±5℃ and diffused for 1, 2.5 and 6 hours respectively and then boronized at 950℃ for 6 hours. The oxidation, hot-corrosion and abrasion resistance behavior were examined. The experimental results showed the compounds of the aluminized layer, from the surface to the matrix, were composed of Fe2Al5 ( η -phase )、 Fe3Al ( β 1-phase ) and α phase. The microstructure of aluminized plus complex boronized were similar to that simplex boronized. The XRD analysis results indicated that there existed Fe2B、 Fe2AlB2 and Fe2Al5 in this kind of layer. The simplex aluminized layers still remained bright gray appearance when oxidized at 950℃, but complex boronized layer was not able to resist oxidization at the temperature. Both the layers of complex boronized and aluminized had the same anti-oxidization level in the circulative oxidization tests, and also good anti-corrosion ability in molten salt medium. Under dry abrasive conditions, wear resistance of complex boronized layer was superior to the aluminized layer.

  4. Cationic schiff base amphiphiles and their metal complexes: Surface and biocidal activities against bacteria and fungi.

    Science.gov (United States)

    Negm, N A; Zaki, M F; Salem, M A I

    2010-05-01

    A series of cationic surfactants containing schiff base groups was synthesized by condensation of four fatty amines namely: dodecyl, tetradecyl, hexadecyl and octadecyl amine and 4-diethyl aminobenzaldehyde (1-4), as well as their metal complexes with divalent transition metal ions including Co, Cu and Mn (5-16). The surface activities of the synthesized surfactants were influenced by their chemical structures and the type of the transition metals. The biological activity measurements of the parent cationic schiff bases showed high efficacy against Gram positive and Gram negative bacterial strains and fungi. While on complexation, the biocidal activity was increased remarkably. The biocidal activity of the tested compounds against sulfur reducing bacteria showed promising results in the field of biocide applications.

  5. Magnetic anisotropy in surface-supported single-ion lanthanide complexes

    CERN Document Server

    Stoll, Paul; Rolf, Daniela; Nickel, Fabian; Xu, Qingyu; Hartmann, Claudia; Umbach, Tobias R; Kopprasch, Jens; Ladenthin, Janina N; Schierle, Enrico; Weschke, Eugen; Czekelius, Constantin; Kuch, Wolfgang; Franke, Katharina J

    2016-01-01

    Single-ion lanthanide-organic complexes can provide stable magnetic moments with well-defined orientation for spintronic applications on the atomic level. Here, we show by a combined experimental approach of scanning tunneling microscopy and X-ray absorption spectroscopy that dysprosium-tris(1,1,1-trifluoro-4-(2-thienyl)-2,4butanedionate) (Dy(tta)$_3$) complexes deposited on a Au(111) surface undergo a molecular distortion, resulting in distinct crystal field symmetry imposed on the Dy ion. This leads to an easy-axis magnetization direction in the ligand plane. Furthermore, we show that tunneling electrons hardly couple to the spin excitations, which we ascribe to the shielded nature of the $4f$ electrons.

  6. 5-level polysilicon surface micromachine technology: Application to complex mechanical systems

    Energy Technology Data Exchange (ETDEWEB)

    Rodgers, M.S.; Sniegowski, J.J.

    1998-06-01

    The authors recently reported on the development of a 5-level poly-ilicon surface micromachine fabrication process consisting of four levels of mechanical poly plus an electrical interconnect layer. They are now reporting on the first components designed for and fabricated in this process. These are demonstration systems, which definitively show that five levels of polysilicon provide greater performance, reliability, and significantly increased functionality. This new technology makes it possible to realize levels of system complexity that have so far only existed on paper, while simultaneously adding to the robustness of many of the individual subassemblies.

  7. Surface Complexation Modeling in Variable Charge Soils: Prediction of Cadmium Adsorption

    Directory of Open Access Journals (Sweden)

    Giuliano Marchi

    2015-10-01

    Full Text Available ABSTRACT Intrinsic equilibrium constants for 22 representative Brazilian Oxisols were estimated from a cadmium adsorption experiment. Equilibrium constants were fitted to two surface complexation models: diffuse layer and constant capacitance. Intrinsic equilibrium constants were optimized by FITEQL and by hand calculation using Visual MINTEQ in sweep mode, and Excel spreadsheets. Data from both models were incorporated into Visual MINTEQ. Constants estimated by FITEQL and incorporated in Visual MINTEQ software failed to predict observed data accurately. However, FITEQL raw output data rendered good results when predicted values were directly compared with observed values, instead of incorporating the estimated constants into Visual MINTEQ. Intrinsic equilibrium constants optimized by hand calculation and incorporated in Visual MINTEQ reliably predicted Cd adsorption reactions on soil surfaces under changing environmental conditions.

  8. Joint body and surface wave tomography applied to the Toba caldera complex (Indonesia)

    Science.gov (United States)

    Jaxybulatov, Kairly; Koulakov, Ivan; Shapiro, Nikolai

    2016-04-01

    We developed a new algorithm for a joint body and surface wave tomography. The algorithm is a modification of the existing LOTOS code (Koulakov, 2009) developed for local earthquake tomography. The input data for the new method are travel times of P and S waves and dispersion curves of Rayleigh and Love waves. The main idea is that the two data types have complementary sensitivities. The body-wave data have good resolution at depth, where we have enough crossing rays between sources and receivers, whereas the surface waves have very good near-surface resolution. The surface wave dispersion curves can be retrieved from the correlations of the ambient seismic noise and in this case the sampled path distribution does not depend on the earthquake sources. The contributions of the two data types to the inversion are controlled by the weighting of the respective equations. One of the clearest cases where such approach may be useful are volcanic systems in subduction zones with their complex magmatic feeding systems that have deep roots in the mantle and intermediate magma chambers in the crust. In these areas, the joint inversion of different types of data helps us to build a comprehensive understanding of the entire system. We apply our algorithm to data collected in the region surrounding the Toba caldera complex (north Sumatra, Indonesia) during two temporary seismic experiments (IRIS, PASSCAL, 1995, GFZ, LAKE TOBA, 2008). We invert 6644 P and 5240 S wave arrivals and ~500 group velocity dispersion curves of Rayleigh and Love waves. We present a series of synthetic tests and real data inversions which show that joint inversion approach gives more reliable results than the separate inversion of two data types. Koulakov, I., LOTOS code for local earthquake tomographic inversion. Benchmarks for testing tomographic algorithms, Bull. seism. Soc. Am., 99(1), 194-214, 2009, doi:10.1785/0120080013

  9. Influence of tailored MLI for complex surface geometries on heat transfer

    Science.gov (United States)

    Neumann, H.; Mayrhofer, R.; Richter, T.

    2015-12-01

    Complex, non-developable surfaces require a tailored multi-layer insulation (MLI) for lowest heat load. The most experiments showing the heat transfer through MLI are performed under quasi-ideal conditions determining the principle insulation quality. But the surface to be insulated in real cryostats implies feed-throughs and other non-developable surface parts. The thermal performance of MLI is degraded significantly at cutting points. To investigate this degrading effect a LN2-filled cylinder with a diameter of 219 mm and a length of 1820 mm was insulated with MLI and the heat load was measured by means of calorimetry. In addition the heat load to an insulated cylinder with eighteen branches was measured. Both cylinders have the same surface of 1.37 m2 for a comparison of the results. This article describes the experiments with different ways of tailoring the MLI for the cylinder with branches and discusses their results. It was shown that the cutting points at the branches have a significant degrading influence on the thermal performance of MLI.

  10. Investigating the thermodynamic stability of Bacillus subtilis spore-uranium(VI) adsorption though surface complexation modeling

    Science.gov (United States)

    Harrold, Z.; Hertel, M.; Gorman-Lewis, D.

    2012-12-01

    Dissolved uranium speciation, mobility, and remediation are increasingly important topics given continued and potential uranium (U) release from mining operations and nuclear waste. Vegetative bacterial cell surfaces are known to adsorb uranium and may influence uranium speciation in the environment. Previous investigations regarding U(VI) adsorption to bacterial spores, a differentiated and dormant cell type with a tough proteinaceous coat, include U adsorption affinity and XAFS data. We investigated the thermodynamic stability of aerobic, pH dependent uranium adsorption to bacterial spore surfaces using purified Bacillus subtilis spores in solution with 5ppm uranium. Adsorption reversibility and kinetic experiments indicate that uranium does not precipitate over the duration of the experiments and equilibrium is reached within 20 minutes. Uranium-spore adsorption edges exhibited adsorption at all pH measured between 2 and 10. Maximum adsorption was achieved around pH 7 and decreased as pH increased above 7. We used surface complexation modeling (SCM) to quantify uranium adsorption based on balanced chemical equations and derive thermodynamic stability constants for discrete uranium-spore adsorption reactions. Site specific thermodynamic stability constants provide insight on interactions occurring between aqueous uranium species and spore surface ligands. The uranium adsorption data and SCM parameters described herein, also provide a basis for predicting the influence of bacterial spores on uranium speciation in natural systems and investigating their potential as biosorption agents in engineered systems.

  11. Auto-pickfi rst breaks with complex raypaths for undulate surface conditions

    Institute of Scientific and Technical Information of China (English)

    An Sheng-Pei; Hu Tian-Yue; Cui Yong-Fu; Duan Wen-Sheng; Peng Geng-Xin

    2015-01-01

    First-break picking is the key step in seismic data processing for surveying undulate surfaces, and directly infl uences the precision of near-surface modeling and effects of static corrections. The currentfi rst-break auto-picking methods may fail when the signal-to-noise ratio (SNR) is low for seismic data in the undulate area, and require labor and time intensive manual picking. This study develops an improved super-virtual interferometry (SVI) method that combines multichannel and multidomain quality control (MMQC) techniques to achieve auto-pickedfi rst breaks. The improved SVI method extends the SVI application to enhance the SNR for near-surface scattered waves for thefi rst time, which allows for the SVI method to adapt tofi rst breaks with complex raypaths by linear combination of refractions and near-surface scattered waves. Methods of inverse and multidomain interferometry are developed to effectively enhance the virtual records extracted by the SVI method. The deconvolution filter for waveforms is used to increase resolution and reduce false picks, while the MMQC technique is designed to auto-correct false picks and increase the stability of auto-pickingfi rst breaks. The robust technique developed in this study enables stable processing of large 3D seismic datasets. Higher quality results are obtained using the approach presented in this paper to actualfi eld data from the mountain areas in western China, when compared to some commonly used commercial software.

  12. PALADYN, a comprehensive land surface-vegetation-carbon cycle model of intermediate complexity

    Science.gov (United States)

    Willeit, Matteo; Ganopolski, Andrey

    2016-04-01

    PALADYN is presented, a new comprehensive and computationally efficient land surface-vegetation-carbon cycle model designed to be used in Earth system models of intermediate complexity for long-term simulations and paleoclimate studies. The model treats in a consistent manner the interaction between atmosphere, terrestrial vegetation and soil through the fluxes of energy, water and carbon. Energy, water and carbon are conserved. The model explicitly treats permafrost, both in physical processes and as important carbon pool. The model distinguishes 9 surface types of which 5 are different vegetation types, bare soil, land ice, lake and ocean shelf. Including the ocean shelf allows to treat continuous changes in sea level and shelf area associated with glacial cycles. Over each surface type the model solves the surface energy balance and computes the fluxes of sensible, latent and ground heat and upward shortwave and longwave radiation. It includes a single snow layer. The soil model distinguishes between three different macro surface types which have their own soil column: vegetation and bare soil, ice sheet and ocean shelf. The soil is vertically discretized into 5 layers where prognostic equations for temperature, water and carbon are consistently solved. Phase changes of water in the soil are explicitly considered. A surface hydrology module computes precipitation interception by vegetation, surface runoff and soil infiltration. The soil water equation is based on Darcy's law. Given soil water content, the wetland fraction is computed based on a topographic index. Photosynthesis is computed using a light use efficiency model. Carbon assimilation by vegetation is coupled to the transpiration of water through stomatal conductance. The model includes a dynamic vegetation module with 5 plant functional types competing for the gridcell share with their respective net primary productivity. Each macro surface type has its own carbon pools represented by a litter, a fast

  13. The potential energy surface of the Ar-CO complex obtained using high-resolution data

    Science.gov (United States)

    Coudert, L. H.; Pak, I.; Surin, L.

    2004-09-01

    A potential energy surface is retrieved for the Ar-CO complex by carrying out a global analysis of its high-resolution spectroscopic data. The data set consists of already published microwave and infrared data and of new microwave transitions which are presented in the paper. The theoretical approach used to reproduce the spectrum is based on a model Hamiltonian which accounts simultaneously for the two large amplitude van der Waals modes and for the overall rotation of the complex. Only the vCO=0 state is considered. The root-mean-square deviation of the analysis is 18 MHz for the microwave data and 1.4×10-3 cm-1 for the infrared energy difference data. Fifteen parameters corresponding to the potential energy function are determined in addition to two kinetic energy parameters and two distortion-type parameters. The potential energy surface derived is in good agreement with the one obtained by Shin, Shin, and Tao [J. Chem. Phys. 104, 183 (1996)].

  14. Formation mechanism of a silane-PVA/PVAc complex film on a glass fiber surface.

    Science.gov (United States)

    Repovsky, Daniel; Jane, Eduard; Palszegi, Tibor; Slobodnik, Marek; Velic, Dusan

    2013-10-21

    Mechanical properties of glass fiber reinforced composite materials are affected by fiber sizing. A complex film formation, based on a silane film and PVA/PVAc (polyvinyl alcohol/polyvinyl acetate) microspheres on a glass fiber surface is determined at 1) the nanoscale by using atomic force microscopy (AFM), and 2) the macroscale by using the zeta potential. Silane groups strongly bind through the Si-O-Si bond to the glass surface, which provides the attachment mechanism as a coupling agent. The silane groups form islands, a homogeneous film, as well as empty sites. The average roughness of the silanized surface is 6.5 nm, whereas it is only 0.6 nm for the non-silanized surface. The silane film vertically penetrates in a honeycomb fashion from the glass surface through the deposited PVA/PVAc microspheres to form a hexagonal close pack structure. The silane film not only penetrates, but also deforms the PVA/PVAc microspheres from the spherical shape in a dispersion to a ellipsoidal shape on the surface with average dimensions of 300/600 nm. The surface area value Sa represents an area of PVA/PVAc microspheres that are not affected by the silane penetration. The areas are found to be 0.2, 0.08, and 0.03 μm(2) if the ellipsoid sizes are 320/570, 300/610, and 270/620 nm for silane concentrations of 0, 3.8, and 7.2 μg mL(-1), respectively. The silane film also moves PVA/PVAc microspheres in the process of complex film formation, from the low silane concentration areas to the complex film area providing enough silane groups to stabilize the structure. The values for the residual silane honeycomb structure heights (Ha ) are 6.5, 7, and 12 nm for silane concentrations of 3.8, 7.2, and 14.3 μg mL(-1), respectively. The pH-dependent zeta-potential results suggest a specific role of the silane groups with effects on the glass fiber surface and also on the PVA/PVAc microspheres. The non-silanized glass fiber surface and the silane film have similar zeta potentials ranging

  15. Three-gradient regular solution model for simple liquids wetting complex surface topologies

    Directory of Open Access Journals (Sweden)

    Sabine Akerboom

    2016-10-01

    Full Text Available We use regular solution theory and implement a three-gradient model for a liquid/vapour system in contact with a complex surface topology to study the shape of a liquid drop in advancing and receding wetting scenarios. More specifically, we study droplets on an inverse opal: spherical cavities in a hexagonal pattern. In line with experimental data, we find that the surface may switch from hydrophilic (contact angle on a smooth surface θY 90°. Both the Wenzel wetting state, that is cavities under the liquid are filled, as well as the Cassie–Baxter wetting state, that is air entrapment in the cavities under the liquid, were observed using our approach, without a discontinuity in the water front shape or in the water advancing contact angle θ. Therefore, air entrapment cannot be the main reason why the contact angle θ for an advancing water front varies. Rather, the contact line is pinned and curved due to the surface structures, inducing curvature perpendicular to the plane in which the contact angle θ is observed, and the contact line does not move in a continuous way, but via depinning transitions. The pinning is not limited to kinks in the surface with angles θkink smaller than the angle θY. Even for θkink > θY, contact line pinning is found. Therefore, the full 3D-structure of the inverse opal, rather than a simple parameter such as the wetting state or θkink, determines the final observed contact angle.

  16. Chemical transformations drive complex self-assembly of uracil on close-packed coinage metal surfaces.

    Science.gov (United States)

    Papageorgiou, Anthoula C; Fischer, Sybille; Reichert, Joachim; Diller, Katharina; Blobner, Florian; Klappenberger, Florian; Allegretti, Francesco; Seitsonen, Ari P; Barth, Johannes V

    2012-03-27

    We address the interplay of adsorption, chemical nature, and self-assembly of uracil on the Ag(111) and Cu(111) surfaces as a function of molecular coverage (0.3 to 1 monolayer) and temperature. We find that both metal surfaces act as templates and the Cu(111) surface acts additionally as a catalyst for the resulting self-assembled structures. With a combination of STM, synchrotron XPS, and NEXAFS studies, we unravel a distinct polymorphism on Cu(111), in stark contrast to what is observed for the case of uracil on the more inert Ag(111) surface. On Ag(111) uracil adsorbs flat and intact and forms close-packed two-dimensional islands. The self-assembly is driven by stable hydrogen-bonded dimers with poor two-dimensional order. On Cu(111) complex structures are observed exhibiting, in addition, a strong annealing temperature dependence. We determine the corresponding structural transformations to be driven by gradual deprotonation of the uracil molecules. Our XPS study reveals unambiguously the tautomeric signature of uracil in the contact layer and on Cu(111) the molecule's deprotonation sites. The metal-mediated deprotonation of uracil and the subsequent electron localization in the molecule determine important biological reactions. Our data show a dependence between molecular coverage and molecule-metal interaction on Cu(111), as the molecules tilt at higher coverages in order to accommodate a higher packing density. After deprotonation of both uracil N atoms, we observe an adsorption geometry that can be understood as coordinative anchoring with a significant charge redistribution in the molecule. DFT calculations are employed to analyze the surface bonding and accurately describe the pertaining electronic structure.

  17. On the relationship between enamel band complexity and occlusal surface area in Equids (Mammalia, Perissodactyla

    Directory of Open Access Journals (Sweden)

    Nicholas A. Famoso

    2016-07-01

    Full Text Available Enamel patterns on the occlusal surfaces of equid teeth are asserted to have tribal-level differences. The most notable example compares the Equini and Hipparionini, where Equini have higher crowned teeth with less enamel-band complexity and less total occlusal enamel than Hipparionini. Whereas previous work has successfully quantified differences in enamel band shape by dividing the length of enamel band by the square root of the occlusal surface area (Occlusal Enamel Index, OEI, it was clear that OEI only partially removes the effect of body size. Because enamel band length scales allometrically, body size still has an influence on OEI, with larger individuals having relatively longer enamel bands than smaller individuals. Fractal dimensionality (D can be scaled to any level, so we have used it to quantify occlusal enamel complexity in a way that allows us to get at an accurate representation of the relationship between complexity and body size. To test the hypothesis of tribal-level complexity differences between Equini and Hipparionini, we digitally traced a sample of 98 teeth, one tooth per individual; 31 Hipparionini and 67 Equini. We restricted our sampling to the P3-M2 to reduce the effect of tooth position. After calculating the D of these teeth with the fractal box method which uses the number of boxes of various sizes to calculate the D of a line, we performed a t-test on the individual values of D for each specimen, comparing the means between the two tribes, and a phylogenetically informed generalized least squares regression (PGLS for each tribe with occlusal surface area as the independent variable and D as the dependent variable. The slopes of both PGLS analyses were compared using a t-test to determine if the same linear relationship existed between the two tribes. The t-test between tribes was significant (p < 0.0001, suggesting different D populations for each lineage. The PGLS for Hipparionini was a positive but not

  18. Excited state potential energy surfaces of bistridentate RuII complexes - A TD-DFT study

    Science.gov (United States)

    Österman, Tomas; Persson, Petter

    2012-10-01

    Time-dependent density functional theory (TD-DFT) calculations have been used to investigate low-energy singlet and triplet excited state potential energy surfaces (PES) of two prototype RuII-bistridentate complexes: [RuII(tpy)2]2+ (tpy is 2,2':6',2''-terpyridine) and [RuII(dqp)2]2+ (dqp is 2,6-di(quinolin-8-yl)pyridine). Solvent effects were considered using a self-consistent reaction field scheme. The calculations provide information about the excited state manifold along pathways for activated decay of metal-to-ligand charge-transfer (MLCT) excited states via metal-centered (MC) states for the two complexes. Significant differences in the energy profiles of the investigated PESs are explained through characterization of the electronic properties of the involved states calculated by the TD-DFT calculations. Finally, implications of the computational results for the design of octahedral metal complexes utilizing ligand field splitting (LFS) strategies for efficient light-harvesting in photochemical applications such as artificial photosynthesis are discussed.

  19. The interaction of streptococcal enolase with canine plasminogen: the role of surfaces in complex formation.

    Directory of Open Access Journals (Sweden)

    Vinod Balhara

    Full Text Available The enolase from Streptococcus pyogenes (Str enolase F137L/E363G is a homo-octamer shaped like a donut. Plasminogen (Pgn is a monomeric protein composed of seven discrete separated domains organized into a lock washer. The enolase is known to bind Pgn. In past work we searched for conditions in which the two proteins would bind to one another. The two native proteins in solution would not bind under any of the tried conditions. We found that if the structures were perturbed binding would occur. We stated that only the non-native Str enolase or Pgn would interact such that we could detect binding. We report here the results of a series of dual polarization interferometry (DPI experiments coupled with atomic force microscopy (AFM, isothermal titration calorimetry (ITC, dynamic light scattering (DLS, and fluorescence. We show that the critical condition for forming stable complexes of the two native proteins involves Str enolase binding to a surface. Surfaces that attract Str enolase are a sufficient condition for binding Pgn. Under certain conditions, Pgn adsorbed to a surface will bind Str enolase.

  20. Ab initio intermolecular potential energy surfaces for the Ar-NCCN van der Waals complexes

    Science.gov (United States)

    Solimannejad, Mohammad; Jouypazadeh, Hamidreza; Farrokhpour, Hossein

    2014-11-01

    The intermolecular potential energy surface of complex pairing argon with cyanogen molecule (NCCN) was calculated using the coupled cluster with single and double and perturbative triple excitations (CCSD(T)) with aug-cc-pvdz basis set extended with a set of mid-bond (3s3p2d1f1g) functions. The interaction energies were calculated by the supermolecular approach with the full counterpoise correction for the basis set superposition error. The calculated potential energies were fitted to an analytical expression. The calculated Ar-NCCN potential energy surface shows a global minimum at 3.35 Å, the distance between argon and centre of mass of cyanogen, for the T-shaped geometry and two local minimum at distance of 5.54 Å for the linear geometry on one side of cyanogen. Finally, the interaction second virial coefficients were calculated using the fitted potential energy surface and were compared with those obtained by the parameters of the Beattie-Bridgeman equation of states of pure argon and cyanogens fluids, approximately.

  1. Surface complexation modeling of Cd(II) sorption to montmorillonite, bacteria, and their composite

    Science.gov (United States)

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

    2016-10-01

    Surface complexation modeling (SCM) has emerged as a powerful tool for simulating heavy metal adsorption processes on the surface of soil solid components under different geochemical conditions. The component additivity (CA) approach is one of the strategies that have been widely used in multicomponent systems. In this study, potentiometric titration, isothermal adsorption, zeta potential measurement, and extended X-ray absorption fine-structure (EXAFS) spectra analysis were conducted to investigate Cd adsorption on 2 : 1 clay mineral montmorillonite, on Gram-positive bacteria Bacillus subtilis, and their mineral-organic composite. We developed constant capacitance models of Cd adsorption on montmorillonite, bacterial cells, and mineral-organic composite. The adsorption behavior of Cd on the surface of the composite was well explained by CA-SCM. Some deviations were observed from the model simulations at pH SCM closely coincided with the estimated value of EXAFS at pH 6. The model could be useful for the prediction of heavy metal distribution at the interface of multicomponents and their risk evaluation in soils and associated environments.

  2. Additive surface complexation modeling of uranium(VI) adsorption onto quartz-sand dominated sediments.

    Science.gov (United States)

    Dong, Wenming; Wan, Jiamin

    2014-06-17

    Many aquifers contaminated by U(VI)-containing acidic plumes are composed predominantly of quartz-sand sediments. The F-Area of the Savannah River Site (SRS) in South Carolina (USA) is an example. To predict U(VI) mobility and natural attenuation, we conducted U(VI) adsorption experiments using the F-Area plume sediments and reference quartz, goethite, and kaolinite. The sediments are composed of ∼96% quartz-sand and 3-4% fine fractions of kaolinite and goethite. We developed a new humic acid adsorption method for determining the relative surface area abundances of goethite and kaolinite in the fine fractions. This method is expected to be applicable to many other binary mineral pairs, and allows successful application of the component additivity (CA) approach based surface complexation modeling (SCM) at the SRS F-Area and other similar aquifers. Our experimental results indicate that quartz has stronger U(VI) adsorption ability per unit surface area than goethite and kaolinite at pH ≤ 4.0. Our modeling results indicate that the binary (goethite/kaolinite) CA-SCM under-predicts U(VI) adsorption to the quartz-sand dominated sediments at pH ≤ 4.0. The new ternary (quartz/goethite/kaolinite) CA-SCM provides excellent predictions. The contributions of quartz-sand, kaolinite, and goethite to U(VI) adsorption and the potential influences of dissolved Al, Si, and Fe are also discussed.

  3. Particles as probes for complex plasmas in front of biased surfaces

    CERN Document Server

    Basner, R; Loffhagen, D; Schubert, G; Fehske, H; Kersten, H

    2008-01-01

    An interesting aspect in the research of complex (dusty) plasmas is the experimental study of the interaction of micro-particles with the surrounding plasma for diagnostic purposes. Local electric fields can be determined from the behaviour of particles in the plasma, e.g. particles may serve as electrostatic probes. Since in many cases of applications in plasma technology it is of great interest to describe the electric field conditions in front of floating or biased surfaces, the confinement and behaviour of test particles is studied in front of floating walls inserted into a plasma as well as in front of additionally biased surfaces. For the latter case, the behaviour of particles in front of an adaptive electrode, which allows for an efficient confinement and manipulation of the grains, has been experimentally studied in dependence on the discharge parameters and on different bias conditions of the electrode. The effect of the partially biased surface (dc, rf) on the charged micro-particles has been inves...

  4. Quantum chemical study of inner-sphere complexes of trivalent lanthanide and actinide ions on the corundum (110) surface

    Energy Technology Data Exchange (ETDEWEB)

    Polly, R.; Schimmelpfennig, B.; Rabung, T.; Kupcik, T.; Klenze, R.; Geckeis, H. [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Inst. fuer Nukleare Entsorgung (INE); Floersheimer, M. [Hochschule RheinMain, Ruesselsheim (Germany). Fachbereich Ingenieurwissenschaften

    2013-11-01

    Sorption plays a major role in the safety assessment of nuclear waste disposal. In the present theoretical study we focused on understanding the interaction of trivalent lanthanides and actinides (La{sup 3+}, Eu{sup 3+} and Cm{sup 3+}) with the corundum (110) surface. Optimization of the structures were carried out using density functional theory with different basis sets. Additionally, Moeller-Plesset perturbation theory of second order was used for single point energy calculations. We studied the structure of different inner-sphere complexes depending on the surface deprotonation and the number of water molecules in the first coordination shell. The most likely structure of the inner-sphere complex (tri- or tetradentate) was predicted. For the calculations we used a cluster model for the surface. By deprotonating the cluster a chemical environment at elevated pH values was mimicked. Our calculations predict the highest stability for a tetradentate inner-sphere surface complexes with five water molecules remaining in the first coordination sphere of the metal ions. The formation of the inner-sphere complexes is favored when a coordination takes place with at most one deprotonated surface aluminol group located beneath the inner-sphere complex. The mutual interaction between sorbing metal ions at the surface is studied as well. The minimal possible distance between two inner-sphere sorbed metal ions at the surface was determined to be 530 pm. (orig.)

  5. Surface rheological properties of liquid-liquid interfaces stabilized by protein fibrillar aggregates and protein-polysaccharide complexes

    NARCIS (Netherlands)

    Humblet-Hua, K.N.P.; Linden, van der E.; Sagis, L.M.C.

    2013-01-01

    In this study we have investigated the surface rheological properties of oil-water interfaces stabilized by fibrils from lysozyme (long and semi-flexible and short and rigid ones), fibrils from ovalbumin (short and semi-flexible), lysozyme-pectin complexes, or ovalbumin-pectin complexes. We have

  6. Method and apparatus for enhanced sequencing of complex molecules using surface-induced dissociation in conjunction with mass spectrometric analysis

    Science.gov (United States)

    Laskin, Julia [Richland, WA; Futrell, Jean H [Richland, WA

    2008-04-29

    The invention relates to a method and apparatus for enhanced sequencing of complex molecules using surface-induced dissociation (SID) in conjunction with mass spectrometric analysis. Results demonstrate formation of a wide distribution of structure-specific fragments having wide sequence coverage useful for sequencing and identifying the complex molecules.

  7. Organometallic electrodes: modification of electrode surfaces through cathodic reduction of cyclopentadienyldiazonium complexes of cobalt and manganese.

    Science.gov (United States)

    Laws, Derek R; Sheats, John; Rheingold, Arnold L; Geiger, William E

    2010-09-21

    Two organometallic complexes having cyclopentadienyldiazonium ligands have been isolated and characterized by spectroscopy, X-ray crystallography, and electrochemistry. Both CoCp(η(5)-C(5)H(4)N(2))(2+) (2(2+)) and Mn(CO)(3)(η(5)-C(5)H(4)N(2))(+) (3(+)) undergo facile cyclopentadienyldiazonium ligand-based one-electron reductions which liberate dinitrogen and result in strong binding of the cyclopentadienyl ligand to a glassy carbon surface, similar to the processes well established for organic aryldiazonium salts. The organometallic-modified electrodes are robust and have a thickness of approximately one monolayer (Γ = (2-4) × 10(-10) mol cm(-2)). Their voltammetric responses are as expected for a cobaltocenium-modified electrode, [CoCp(η(5)-C(5)H(4)-E)](+), where Cp = cyclopentadienyl and E = electrode, and a "cymantrene"-modified electrode Mn(CO)(3)(η(5)-C(5)H(4)-E). The cobaltocenium electrode has two cathodic surface waves. The first (E(1/2) = -1.34 V vs ferrocene) is highly reversible, whereas the second (E(pc) = -2.4 V) is not, consistent with the known behavior of cobaltocenium. The cymantrene-substituted electrode has a partially chemically reversible anodic wave at E(1/2) = 0.96 V, also consistent with the behavior of its Mn(CO)(3)Cp parent. Many of the properties of aryl-modified electrodes, such as "blockage" of the voltammetric responses of test analytes, are also seen for the organometallic-modified electrodes. Surface-based substitution of a carbonyl group by a phosphite ligand, P(OR)(3), R = Ph or Me, was observed when the cymantrene-modified electrode was anodically oxidized in the presence of a phosphite ligand. The successful grafting of organometallic moieties by direct bonding of a cyclopentadienyl ligand to electrode surfaces expands the chemical and electrochemical dimensions of diazonium-based modified electrodes.

  8. Characterization of a complex near-surface structure using well logging and passive seismic measurements

    Science.gov (United States)

    Benjumea, Beatriz; Macau, Albert; Gabàs, Anna; Figueras, Sara

    2016-04-01

    We combine geophysical well logging and passive seismic measurements to characterize the near-surface geology of an area located in Hontomin, Burgos (Spain). This area has some near-surface challenges for a geophysical study. The irregular topography is characterized by limestone outcrops and unconsolidated sediments areas. Additionally, the near-surface geology includes an upper layer of pure limestones overlying marly limestones and marls (Upper Cretaceous). These materials lie on top of Low Cretaceous siliciclastic sediments (sandstones, clays, gravels). In any case, a layer with reduced velocity is expected. The geophysical data sets used in this study include sonic and gamma-ray logs at two boreholes and passive seismic measurements: three arrays and 224 seismic stations for applying the horizontal-to-vertical amplitude spectra ratio method (H/V). Well-logging data define two significant changes in the P-wave-velocity log within the Upper Cretaceous layer and one more at the Upper to Lower Cretaceous contact. This technique has also been used for refining the geological interpretation. The passive seismic measurements provide a map of sediment thickness with a maximum of around 40 m and shear-wave velocity profiles from the array technique. A comparison between seismic velocity coming from well logging and array measurements defines the resolution limits of the passive seismic techniques and helps it to be interpreted. This study shows how these low-cost techniques can provide useful information about near-surface complexity that could be used for designing a geophysical field survey or for seismic processing steps such as statics or imaging.

  9. Exotic phenomena in 4f systems: From complex magnetism to surface conduction

    Science.gov (United States)

    Thomas, Sean Michael

    For materials synthesized with f-electron elements, the interaction between f-electrons and conduction electrons often leads to interesting physics. As the temperature is lowered, the f-electrons can hybridize with the conduction electrons in a process known as the Kondo effect. In a Kondo lattice material, the screening may become coherent at the so-called coherence temperature T*. The resulting material is often metallic, containing heavy bands with effective masses many times larger than the free electron mass. In some cases, the development of coherence leads to a filled heavy-electron band where the chemical potential lies within the hybridization gap, resulting in insulating behavior. CeAgBi2 is an antiferromagnetic compound (TN = 6.4 K) belonging to the former (metallic) case. The close energy scales of the Kondo coherence, antiferromagnetism, and crystal field levels results in complex physical properties. Transport measurements reveal a coupling between the different magnetic phases and Hall resistivity. As the field is increased, the antiferromagnetic transition temperature is suppressed to zero Kelvin. Typically, this is expected to result in a quantum critical point. However, due to strange transport behavior in the paramagnetic regime, the usual signatures of quantum criticality are hidden. SmB6 is a Kondo insulator due to the fact that the hybridization results in the opening of a gap. However, as the temperature is further lowered, the resistance saturates. Originally believed to be due to in-gap conduction states in the bulk, the true reason for the resistance saturation is a robust conducting surface state. Several theories predict that the surface state is a result of SmB6 belonging to a class of materials known as topological insulators. However, direct imaging of the spin-momentum locking of the surface states indicative of a topological insulator has proved elusive. Through transport and magnetic measurements, indirect evidence of the nature of

  10. To address surface reaction network complexity using scaling relations machine learning and DFT calculations

    Science.gov (United States)

    Ulissi, Zachary W.; Medford, Andrew J.; Bligaard, Thomas; Nørskov, Jens K.

    2017-01-01

    Surface reaction networks involving hydrocarbons exhibit enormous complexity with thousands of species and reactions for all but the very simplest of chemistries. We present a framework for optimization under uncertainty for heterogeneous catalysis reaction networks using surrogate models that are trained on the fly. The surrogate model is constructed by teaching a Gaussian process adsorption energies based on group additivity fingerprints, combined with transition-state scaling relations and a simple classifier for determining the rate-limiting step. The surrogate model is iteratively used to predict the most important reaction step to be calculated explicitly with computationally demanding electronic structure theory. Applying these methods to the reaction of syngas on rhodium(111), we identify the most likely reaction mechanism. Propagating uncertainty throughout this process yields the likelihood that the final mechanism is complete given measurements on only a subset of the entire network and uncertainty in the underlying density functional theory calculations. PMID:28262694

  11. Using advanced surface complexation models for modelling soil chemistry under forests: Solling forest, Germany.

    Science.gov (United States)

    Bonten, Luc T C; Groenenberg, Jan E; Meesenburg, Henning; de Vries, Wim

    2011-10-01

    Various dynamic soil chemistry models have been developed to gain insight into impacts of atmospheric deposition of sulphur, nitrogen and other elements on soil and soil solution chemistry. Sorption parameters for anions and cations are generally calibrated for each site, which hampers extrapolation in space and time. On the other hand, recently developed surface complexation models (SCMs) have been successful in predicting ion sorption for static systems using generic parameter sets. This study reports the inclusion of an assemblage of these SCMs in the dynamic soil chemistry model SMARTml and applies this model to a spruce forest site in Solling Germany. Parameters for SCMs were taken from generic datasets and not calibrated. Nevertheless, modelling results for major elements matched observations well. Further, trace metals were included in the model, also using the existing framework of SCMs. The model predicted sorption for most trace elements well.

  12. To address surface reaction network complexity using scaling relations machine learning and DFT calculations

    Science.gov (United States)

    Ulissi, Zachary W.; Medford, Andrew J.; Bligaard, Thomas; Nørskov, Jens K.

    2017-03-01

    Surface reaction networks involving hydrocarbons exhibit enormous complexity with thousands of species and reactions for all but the very simplest of chemistries. We present a framework for optimization under uncertainty for heterogeneous catalysis reaction networks using surrogate models that are trained on the fly. The surrogate model is constructed by teaching a Gaussian process adsorption energies based on group additivity fingerprints, combined with transition-state scaling relations and a simple classifier for determining the rate-limiting step. The surrogate model is iteratively used to predict the most important reaction step to be calculated explicitly with computationally demanding electronic structure theory. Applying these methods to the reaction of syngas on rhodium(111), we identify the most likely reaction mechanism. Propagating uncertainty throughout this process yields the likelihood that the final mechanism is complete given measurements on only a subset of the entire network and uncertainty in the underlying density functional theory calculations.

  13. Modeling the surface complexation of calcium at the rutile-water interface to 250°C

    Science.gov (United States)

    Ridley, Moira K.; Machesky, Michael L.; Wesolowski, David J.; Palmer, Donald A.

    2004-01-01

    The adsorption behavior of metal-(hydr)oxide surfaces can be described and rationalized using a variety of surface complexation models. However, these models do not uniquely describe experimental data unless some additional insight into actual binding mechanisms for a given system is available. This paper presents the results of applying the MUlti SIte Complexation or MUSIC model, coupled with a Stern-based three layer description of the electric double layer, to Ca 2+ adsorption data on rutile surfaces from 25 to 250°C in 0.03 and 0.30 m NaCl background electrolyte. Model results reveal that the tetradentate adsorption configuration found for Sr 2+ adsorbed on the rutile (110) surface in the in situ X-ray standing wave experiments of Fenter et al. (2000) provides a good fit to all Ca 2+ adsorption data. Furthermore, it is also shown that equally good fits result from other plausible adsorption complexes, including various monodentate and bidentate adsorption configurations. These results amply demonstrate the utility of in situ spectroscopic data to constrain surface complexation modeling, and the ability of the MUSIC model approach to accommodate this spectroscopic information. Moreover, this is the first use of any surface complexation model to describe multivalent ion adsorption systematically into the hydrothermal regime.

  14. Using Google Earth Surface Metrics to Predict Plant Species Richness in a Complex Landscape

    Directory of Open Access Journals (Sweden)

    Sebastián Block

    2016-10-01

    Full Text Available Google Earth provides a freely available, global mosaic of high-resolution imagery from different sensors that has become popular in environmental and ecological studies. However, such imagery lacks the near-infrared band often used in studying vegetation, thus its potential for estimating vegetation properties remains unclear. In this study, we assess the potential of Google Earth imagery to describe and predict vegetation attributes. Further, we compare it to the potential of SPOT imagery, which has additional spectral information. We measured basal area, vegetation height, crown cover, density of individuals, and species richness in 60 plots in the oak forests of a complex volcanic landscape in central Mexico. We modelled each vegetation attribute as a function of surface metrics derived from Google Earth and SPOT images, and selected the best-supported linear models from each source. Total species richness was the best-described and predicted variable: the best Google Earth-based model explained nearly as much variation in species richness as its SPOT counterpart (R2 = 0.44 and 0.51, respectively. However, Google Earth metrics emerged as poor predictors of all remaining vegetation attributes, whilst SPOT metrics showed potential for predicting vegetation height. We conclude that Google Earth imagery can be used to estimate species richness in complex landscapes. As it is freely available, Google Earth can broaden the use of remote sensing by researchers and managers in low-income tropical countries where most biodiversity hotspots are found.

  15. Ab initio potential energy surface and bound states for the Kr-OCS complex.

    Science.gov (United States)

    Feng, Eryin; Sun, Chunyan; Yu, Chunhua; Shao, Xi; Huang, Wuying

    2011-09-28

    The first ab initio potential energy surface of the Kr-OCS complex is developed using the coupled-cluster singles and doubles with noniterative inclusion of connected triples [CCSD(T)]. The mixed basis sets, aug-cc-pVTZ for the O, C, and S atom, and aug-cc-pVQZ-PP for the Kr atom, with an additional (3s3p2d1f) set of midbond functions are used. A potential model is represented by an analytical function whose parameters are fitted numerically to the single point energies computed at 228 configurations. The potential has a T-shaped global minimum and a local linear minimum. The global minimum occurs at R = 7.146 a(0), θ = 105.0° with energy of -270.73 cm(-1). Bound state energies up to J = 9 are calculated for three isotopomers (82)Kr-OCS, (84)Kr-OCS, and (86)Kr-OCS. Analysis of the vibrational wavefunctions and energies suggests the complex can exist in two isomeric forms: T-shaped and quasi-linear. The calculated transition frequencies and spectroscopic constants of the three isotopomers are in good agreement with the experimental values.

  16. Diazonium salt derivatives of osmium bipyridine complexes: Electrochemical grafting and characterisation of modified surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Garrett, David J. [MacDiarmid Institute for Advanced Materials and Nanotechnology, Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch (New Zealand); Jenkins, Peter [School of Chemistry, National University of Ireland, Galway (Ireland); Polson, Matthew I.J. [Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch (New Zealand); Leech, Donal [School of Chemistry, National University of Ireland, Galway (Ireland); Baronian, Keith H.R. [School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch (New Zealand); Downard, Alison J., E-mail: alison.downard@canterbury.ac.n [MacDiarmid Institute for Advanced Materials and Nanotechnology, Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch (New Zealand)

    2011-02-01

    Osmium bipyridine complexes were directly grafted to carbon electrodes through electroreduction of the diazonium salts [Os(bpy-ph-N{sub 2}{sup +}){sub 3}](PF{sub 6}){sub 5} (1) and [Os(bpy-ph-N{sub 2}{sup +}){sub 2}Cl{sub 2}](PF{sub 6}){sub 2} (2). Growth of the films was not self-limiting as is usually found for grafting from diazonium salts. It appears that electron hopping through the bipyridine ligands of the immobilised complexes enables film growth to continue at a constant rate during grafting by potential cycling. The surface concentrations of deposited films were measured electrochemically and the film thicknesses were measured by depth-profiling using the atomic force microscope. Films up to 42 nm thick were prepared with no evidence for slowing of film growth. The grafted films exhibited high stability when repetitively cycled through the Os{sup 2+/3+} couple and electron transfer rate constants of 11.4 s{sup -1} and 35.4 s{sup -1} were measured in ACN and PBS, respectively, for the Os{sup 2+/3+} couple of the film grafted from 1.

  17. Petroleum-collecting and dispersing complexes based on oleic acid and nitrogenous compounds as surface-active agents for removing thin petroleum films from water surface.

    Science.gov (United States)

    Asadov, Ziyafaddin H; Tantawy, Ahmed H; Zarbaliyeva, Ilhama A; Rahimov, Ravan A

    2012-01-01

    Petroleum-collecting and dispersing complexes were synthesized on the basis of oleic acid and nitrogen-containing compounds. Surface-active properties (interfacial tension) of the obtained complexes were investigated by stalagmometric method. Petroleum-collecting and dispersing properties of the oleic acid complexes in diluted (5% wt. water or alcoholic solution) and undiluted form have been studied in waters of varying salinity (distilled, fresh and sea waters). Some of physico-chemical indices of the prepared compounds such as solubility, acid and amine numbers as well as electrical conductivity have been determined. The ability of oleic acid complex with ethylenediamine as petro-collecting and dispersing agent towards different types of petroleum has been studied. The influence of thickness and "age" of the petroleum slick on collecting and dispersing capacity of this complex has been clarified. Surface properties studied included critical micelle concentration (CMC), maximum surface excess (Γ(max)), and minimum surface area (A(min)). Free energies of micellization (ΔG°(mic)) and adsorption (ΔG°(ads)) were calculated.

  18. Complexity

    CERN Document Server

    Gershenson, Carlos

    2011-01-01

    The term complexity derives etymologically from the Latin plexus, which means interwoven. Intuitively, this implies that something complex is composed by elements that are difficult to separate. This difficulty arises from the relevant interactions that take place between components. This lack of separability is at odds with the classical scientific method - which has been used since the times of Galileo, Newton, Descartes, and Laplace - and has also influenced philosophy and engineering. In recent decades, the scientific study of complexity and complex systems has proposed a paradigm shift in science and philosophy, proposing novel methods that take into account relevant interactions.

  19. Cycloheptaamylose-dansyl chloride complex as a fluorescent label of surface membranes in living ciliates.

    Science.gov (United States)

    Wyroba, E; Bottiroli, G; Giordano, P

    1981-12-01

    Labelling of surface membrane of living ciliates: Paramecium aurelia and Tetrahymena pyriformis with fluorescent compound--cycloheptaamylose-dansyl chloride complex (CDC) has been achieved. Fluorescence micrographs of the dried samples showed specific localization of CDC on the cell membrane without any intracellular penetration. On the contrary the ciliates which have been dead during labelling revealed a non-specific fluorescence of their whole bodies. Microspectrofluorimetric analysis of labelled Paramecium cells was performed with Leitz microspectrograph. Spectrum of fluorescence emission measured over the cell membrane level had maximum at 450 nm. Strikingly, the emission maximum of the cells dead at the moment of labelling was shifted 10 nm to a longer wavelength. The rate of photofading measured in this case was almost 3-fold higher than for the ciliates labelled as living ones. Fluorescence excitation spectra did not show any difference in the peak position. Thus CDC staining appears to be an useful method of supravital labelling of cell surface enabling also to distinguish--on the basis of spectral characteristics--the ciliates being alive from those dead at the moment of fluorochrome binding.

  20. Imaging of complex basin structures with the common reflection surface (CRS) stack method

    Science.gov (United States)

    Menyoli, Elive; Gajewski, Dirk; Hübscher, Christian

    2004-06-01

    Common reflection surface (CRS) stack technology is applied to seismic data from certain areas of the Donbas Foldbelt, Ukraine, after conventional seismic methods gave unsatisfactory results. On the conventionally processed post-stack migrated section the areas of interest already showed clear features of the basin structure, but reflector continuity and image quality were poor. It was our objective to improve the image quality in these areas to better support the geological interpretation and the model building. In contrast to the standard common mid-point (CMP) stack, in which a stacking trajectory is used, the CRS method transforms pre-processed multicoverage data into a zero-offset section by summing along stacking surfaces. The stacking operator is an approximation of the reflection response of a curved interface in an inhomogeneous medium. The primary advantage of the data-driven CRS stack method is its model independence and the enhancement of the signal-to-noise ratio of the stacked sections through a stacking reflection response along traces from more than one CMP gather. The presented results show that the multifold strength of the CRS stack is of particular advantage in the case of complex inverted features of Devonian-Carboniferous sediments in the Donbas Foldbelt data. We observe that in these areas where the confidence level for picking and interpretation of the stacking velocity model is low, imaging without a macrovelocity model gives improved results, because errors due to wrong or poor stacking velocity models are avoided.

  1. An accurate three-dimensional potential energy surface for the He-Na2 complex

    Institute of Scientific and Technical Information of China (English)

    WANG Yue; HUANG WuYing; FENG ErYin; CUI ZhiFeng

    2008-01-01

    An accurate three-dimensional potential energy surface (PES) for the He-Na2 van der Waals complex was calculated at the coupled cluster singles-and-doubles with noniterative inclusion of connected triple (CCSD(T)) level of theory. A mixed basis set, aug-cc-pVQZ for the He atom and cc-pCVQZ for the sodium atom, and an additional (3s3p2dlf) set of midbond functions were used. The computed inter-action energies in 819 configurations were fitted to a 96-parameter analytic potential model by least squares fitting. The PES has two shallow wells corresponding to the T-shaped structure and the linear configuration, which are located at 12.5a0 and 14 a0 with depths of 1.769 and 1.684 cm-1, respectively. The whole potential energy surface exhibits weak anisotropy. Based on the fitted PES, state-to-state differential cross sections were calculated.

  2. Yeast surface display of a noncovalent MHC class II heterodimer complexed with antigenic peptide.

    Science.gov (United States)

    Boder, Eric T; Bill, Jerome R; Nields, Andrew W; Marrack, Philippa C; Kappler, John W

    2005-11-20

    Microbial protein display technologies have enabled directed molecular evolution of binding and stability properties in numerous protein systems. In particular, dramatic improvements to antibody binding affinity and kinetics have been accomplished using these tools in recent years. Examples of successful application of display technologies to other immunological proteins have been limited to date. Herein, we describe the expression of human class II major histocompatibility complex allele (MHCII) HLA-DR4 on the surface of Saccharomyces cerevisiae as a noncovalently associated heterodimer. The yeast-displayed MHCII is fully native as assessed by binding of conformationally specific monoclonal antibodies; failure of antibodies specific for empty HLA-DR4 to bind yeast-displayed protein indicates antigenic peptide is bound. This report represents the first example of a noncovalent protein dimer displayed on yeast and of successful display of wild-type MHCII. Results further point to the potential for using yeast surface display for engineering and analyzing the antigen binding properties of MHCII.

  3. Predicting the infrared transition intensities in the Ar-HF complex: the key role of the dipole moment surface accuracy.

    Science.gov (United States)

    Jankowski, Piotr; Ziółkowski, Marcin

    2008-01-21

    The method proposed earlier for the generation of the full-dimensional energy surface for van der Waals complexes [P. Jankowski, J. Chem. Phys. 121, 1655 (2004)] is used to obtain a fulldimensional dipole moment surface for the atom-diatom complex in calculations based on the coupled-cluster with single, double, and noniterative triple excitation approach and the aug-cc-pVQZ basis sets. This surface has been employed to calculate transition intensities of the infrared spectra of Ar-HF. Special attention has been paid to study the problem of relative intensities of the different bands which have not been properly predicted within the long-range models of the dipole moment [A. E. Thornley and J. M. Hutson, J. Chem. Phys. 101, 5578 (1994)]. The intensities calculated with the present dipole moment surface agree very well with the experimental data, which indicate that the short-range interactions significantly affect the dipole moment surface and the calculated intensities. To investigate the role of the accuracy of the dipole moment surface on infrared transition intensities in atom-diatom complexes, four models of increasing complexity are studied. Their performance is shown to strongly depend on the region of the interaction energy surface probed by the initial and final states of the individual transitions.

  4. Engineering yeast consortia for surface-display of complex cellulosome structures

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wilfred [University of Delaware

    2014-03-31

    As our society marches toward a more technologically advanced future, energy and environmental sustainability are some of the most challenging problems we face today. Biomass is one of the most abundant renewable-feedstock for sustainable production of biofuels. However, the main technological obstacle to more widespread uses of this resource is the lack of low-cost technologies to overcome the recalcitrant nature of the cellulosic structure, especially the hydrolysis step on highly ordered celluloses. In this proposal, we successfully engineered several efficient and inexpensive whole-cell biocatalysts in an effort to produce economically compatible and sustainable biofuels, namely cellulosic ethanol. Our approach was to display of a highly efficient cellulolytic enzyme complex, named cellulosome, on the surface of a historical ethanol producer Saccharomyces cerevisiae for the simultaneous and synergistic saccharification and fermentation of cellulose to ethanol. We first demonstrated the feasibility of assembling a mini-cellulosome by incubating E. coli lysates expressing three different cellulases. Resting cells displaying mini-cellulosomes produced 4-fold more ethanol from phosphoric acid-swollen cellulose (PASC) than cultures with only added enzymes. The flexibility to assemble the mini-cellulosome structure was further demonstrated using a synthetic yeast consortium through intracellular complementation. Direct ethanol production from PASC was demonstrated with resting cell cultures. To create a microorganism suitable for a more cost-effective process, called consolidated bioprocessing (CBP), a synthetic consortium capable of displaying mini-cellulosomes on the cell surface via intercellular complementation was created. To further improve the efficiency, a new adaptive strategy of employing anchoring and adaptor scaffoldins to amplify the number of enzymatic subunits was developed, resulting in the creation of an artificial tetravalent cellulosome on the

  5. Complex

    African Journals Online (AJOL)

    CLEMENT O BEWAJI

    Schiff bases and their complex compounds have been studied for their .... establishing coordination of the N–(2 – hydroxybenzyl) - L - α - valine Schiff base ..... (1967); “Spectrophotometric Identification of Organic Compounds”, Willey, New.

  6. A complex magnetic structure of ultrathin Fe films on Rh (001) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Takada, Masaki [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, 06120 Halle (Germany); Lana Gastelois, Pedro [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, 06120 Halle (Germany); Servico de Nanotecnologia, Centro de Desenvolvimento da Tecnologia Nuclear, 31270-901 BeloHorizonte, MG (Brazil); Przybylski, Marek, E-mail: mprzybyl@mpi-halle.de [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, 06120 Halle (Germany); Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, 30-059 Krakow (Poland); Kirschner, Juergen [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, 06120 Halle (Germany); Naturwissenschaftliche Fakultaet II, Martin-Luther-Universitaet Halle-Wittenberg, 06120 Halle (Germany)

    2013-03-15

    We conducted a structural and magnetic analysis of ultrathin Fe films on Rh (001) surfaces by using low electron energy diffraction (LEED), magneto-optical Kerr effects (MOKE) and spin-polarized scanning tunneling microscopy (SP-STM). The films in the investigated thickness range up to 6 monolayers (ML) are pseudomorphic to the Rh (001) substrate. While Fe films thinner than 3 ML grow layer-by-layer at room temperature (RT), Fe films thicker than 4 ML form islands. 1 ML Fe films do not show any hysteresis loops even at low temperature. Polar hysteresis loops for the 2 ML and 3 ML thick films appear at low temperatures. When 1 ML thick Fe films were studied by Cr- and Fe-coated W tips, a (2 Multiplication-Sign 3) and stripe structures were observed, respectively. The structures originate from a complex magnetic structure of 1 ML Fe. Based on the SP-STM results we propose a spin configuration model of a 1 ML Fe film. - Highlights: Black-Right-Pointing-Pointer We studied structural and magnetic properties of Fe films grown on an Rh (001). Black-Right-Pointing-Pointer MOKE measurements revealed that Fe films thicker than 2 ML are ferromagnetic at 5 K. Black-Right-Pointing-Pointer Fe films with thickness of 2 ML and 3 ML exhibit out-of-plane magnetization, those thicker than 4 ML show in-plane magnetization. Black-Right-Pointing-Pointer 1 ML Fe films have a complex magnetic configuration with zero net magnetization. Black-Right-Pointing-Pointer A spin configuration model of 1 ML Fe is proposed based on an SP-STM observation.

  7. Effect of glutamic acid on copper sorption onto kaolinite - Batch experiments and surface complexation modeling.

    Science.gov (United States)

    Karimzadeh, Lotfollah; Barthen, Robert; Stockmann, Madlen; Gruendig, Marion; Franke, Karsten; Lippmann-Pipke, Johanna

    2017-07-01

    High carbonate content of the European Kupferschiefer ore deposits is a challenge for acid copper leaching (pH ≤ 2). Therefore investigating the mobility behavior of Cu(II) under conditions related to an alternative, neutrophil biohydrometallurgical Cu(II) leaching approach is of interest. As glutamic acid (Glu) might be present as a component in the growth media, we studied its effects on the adsorption of Cu(II) onto kaolinite. The binary and ternary batch sorption measurements of Cu(II) and Glu onto kaolinite were performed in the presence of 10 mM NaClO4 as background electrolyte and at a pH range from 4 to 9. Sorption experiments were modeled by the charge-distribution multi-site ion complexation (CD-MUSIC) model by using single sorption site (≡SOH) and monodentate surface complexation reactions. Glu sorption on kaolinite is weak (<10%) and independent of pH. Furthermore, Glu slightly enhances the Cu(II) sorption at low pH but strongly hinders (up to 50%) the sorption at higher pH and therewith enhances copper mobility. The results of isotherms show that Cu(II)-Glu sorption onto kaolinite mimics the Freundlich model. The proposed CD-MUSIC model provides a close fit to the experimental data and predicts the sorption of Cu(II), Cu(II)-Glu and Glu onto kaolinite as well as the effect of Glu on Cu(II) mobility. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Mathematical Optimal Sequence Model Development to Process Planes and Other Interconnected Surfaces of Complex Body Parts

    Directory of Open Access Journals (Sweden)

    I. I. Kravchenko

    2016-01-01

    Full Text Available Experience in application of multi-operational machines CNC (MOM CNC shows that they are efficient only in case of significantly increasing productivity and dramatically reducing time-to-market cycle of new products. Most full technological MOM capabilities are revealed when processing the complex body parts. The more complex is a part design and the more is its number of machined surfaces, the more tools are necessary for its processing and positioning, the more is an efficiency of their application. At the same time, the case history of using these machines in industry shows that MOM CNC are, virtually, used mostly for technological processes of universal equipment, which is absolutely unacceptable. One way to improve the processing performance on MOM CNC is to reduce nonproductive machine time through reducing the mutual idle movements of the working machine. This problem is solved using dynamic programming methods, one of which is the solution of the traveling salesman problem (Bellman's method. With a known plan for treatment of all elementary surfaces of the body part, i.e. the known number of performed transitions, each transition is represented as a vertex of some graph, while technological links between the vertices are its edges. A mathematical model is developed on the Bellman principle, which is adapted to technological tasks to minimize the idle time of mutual idle movements of the working machine to perform all transitions in the optimal sequence. The initial data to fill matrix of time expenditures are time consumed by the hardware after executing the i-th transition, and necessary to complete the j-transition. The programmer fills in matrix cells according to known routing body part taking into account the time for part and table positioning, tool exchange, spindle and table approach to the working zone, and the time of table rotation, etc. The mathematical model was tested when machining the body part with 36 transitions on the

  9. Robust affine-invariant feature points matching for 3D surface reconstruction of complex landslide scenes

    Science.gov (United States)

    Stumpf, André; Malet, Jean-Philippe; Allemand, Pascal; Skupinski, Grzegorz; Deseilligny, Marc-Pierrot

    2013-04-01

    Multi-view stereo surface reconstruction from dense terrestrial photographs is being increasingly applied for geoscience applications such as quantitative geomorphology, and a number of different software solution and processing streamlines have been suggested. For image matching, camera self-calibration and bundle block adjustment, most approaches make use of scale-invariant feature transform (SIFT) to identify homologous points in multiple images. SIFT-like point matching is robust to apparent translation, rotation, and scaling of objects in multiple viewing geometries but the number of correctly identified matching points typically declines drastically with increasing angles between the viewpoints. For the application of multi-view stereo of complex landslide scenes, the viewing geometry is often constrained by the local topography and barriers such as rocks and vegetation occluding the target. Under such conditions it is not uncommon to encounter view angle differences of > 30% that hinder the image matching and eventually prohibit the joint estimation of the camera parameters from all views. Recently an affine invariant extension of the SIFT detector (ASIFT) has been demonstrated to provide more robust matches when large view-angle differences become an issue. In this study the ASIFT detector was adopted to detect homologous points in terrestrial photographs preceding 3D reconstruction of different parts (main scarp, toe) of the Super-Sauze landslide (Southern French Alps). 3D surface models for different time periods and different parts of the landslide were derived using the multi-view stereo framework implemented in MicMac (©IGN). The obtained 3D models were compared with reconstructions using the traditional SIFT detectors as well as alternative structure-from-motion implementations. An estimate of the absolute accuracy of the photogrammetric models was obtained through co-registration and comparison with high-resolution terrestrial LiDAR scans.

  10. Current trend in fabrication of complex morphologically tunable superhydrophobic nano scale surfaces

    Science.gov (United States)

    Abdulhussein, Ali T.; Kannarpady, Ganesh K.; Wright, Andrew B.; Ghosh, Anindya; Biris, Alexandru S.

    2016-10-01

    Superhydrophobic surfaces are found in nature and possess several fascinating properties, including the ability to self-clean. A typical superhydrophobic surface has micro/nanostructure roughness and low surface energy, which combine to give it its unusual anti-wetting properties. Because of their unique capabilities, these surfaces have interested scientists in research and industry fields for years. In recent decades, researchers have developed a number of synthetic methods for producing novel superhydrophobic surfaces that mimic natural surfaces. These synthetic surfaces have been widely applied on different types of substrates for potential widespread, practical applications. This review article focuses on these advances in fabricating manmade superhydrophobic surfaces.

  11. Computing the force distribution on the surface of complex, deforming geometries using vortex methods and Brinkman penalization

    CERN Document Server

    Verma, Siddhartha; Novati, Guido; Koumoutsakos, Petros

    2016-01-01

    The distribution of forces on the surface of complex, deforming geometries is an invaluable output of flow simulations. One particular example of such geometries involves self-propelled swimmers. Surface forces can provide significant information about the flow field sensed by the swimmers, and are difficult to obtain experimentally. At the same time, simulations of flow around complex, deforming shapes can be computationally prohibitive when body-fitted grids are used. Alternatively, such simulations may employ penalization techniques. Penalization methods rely on simple Cartesian grids to discretize the governing equations, which are enhanced by a penalty term to account for the boundary conditions. They have been shown to provide a robust estimation of mean quantities, such as drag and propulsion velocity, but the computation of surface force distribution remains a challenge. We present a method for determining flow- induced forces on the surface of both rigid and deforming bodies, in simulations using re-...

  12. Response surface optimization of bioremediation of Acid black 52 (Cr complex dye) using Aspergillus tamarii.

    Science.gov (United States)

    Ghosh, Arpita; Dastidar, Manisha Ghosh; Sreekrishnan, T R

    2017-02-01

    Bioremediation of the Cr complex dye (Acid black 52) was performed in batch and continuous modes using growing Aspergillus tamarii. The removal of Cu which may be present as an impurity was 100% at 100 mg/L initial dye concentration. The removal of color and Cr decreased from 87% to 4% and from 92% to 8%, respectively, by increasing dye concentration from 100 to 5000 mg/L in batch mode. The removal of color and Cr increased from 27% to 67.8% and from 32% to 72%, respectively, with increasing hydraulic retention time from 28 to 220 h at 100 mg/L dye concentration in continuous mode. For optimization of color removal using response surface methodology (RSM) the ranges of parameters were kept at dye concentration: 200-500 mg/L; pH: 4-6 and time: 35-50 hours. Maximum color removal suggested by the model was 85.6809% at initial dye concentration 200 mg/L, pH 5.25 and time 50 h. The validation experiments in batch and continuous modes were conducted at the optimum conditions as suggested by the RSM model. The theoretical and experimental responses of color removal were in close agreement in batch mode. The scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy and gas chromatography-mass spectroscopy analyses indicated biosorption and biodegradation of dye.

  13. Droplets, Evaporation and a Superhydrophobic Surface: Simple Tools for Guiding Colloidal Particles into Complex Materials

    Directory of Open Access Journals (Sweden)

    Marcel Sperling

    2017-05-01

    Full Text Available The formation of complexly structured and shaped supraparticles can be achieved by evaporation-induced self-assembly (EISA starting from colloidal dispersions deposited on a solid surface; often a superhydrophobic one. This versatile and interesting approach allows for generating rather complex particles with corresponding functionality in a simple and scalable fashion. The versatility is based on the aspect that basically one can employ an endless number of combinations of components in the colloidal starting solution. In addition, the structure and properties of the prepared supraparticles may be modified by appropriately controlling the evaporation process, e.g., by external parameters. In this review, we focus on controlling the shape and internal structure of such supraparticles, as well as imparted functionalities, which for instance could be catalytic, optical or electronic properties. The catalytic properties can also result in self-propelling (supra-particles. Quite a number of experimental investigations have been performed in this field, which are compared in this review and systematically explained.

  14. Laser-induced periodic surface structures of thin, complex multi-component films

    Science.gov (United States)

    Reif, Juergen; Varlamova, Olga; Ratzke, Markus; Uhlig, Sebastian

    2016-04-01

    Femtosecond laser-induced regular nanostructures are generated on a complex multilayer target, namely a piece of a commercial, used hard disk memory. It is shown that after single-shot 800-nm irradiation at 0.26 J/cm2 only the polymer cover layer and—in the center—a portion of the magnetic multilayer are ablated. A regular array of linearly aligned spherical 450-nm features at the uncovered interface between cover and magnetic layers appears not to be produced by the irradiation. Only after about 10 pulses on one spot, classical ripples perpendicular to the laser polarization with a period of ≈700 nm are observed, with a modulation between 40 nm above and 40 nm below the pristine surface and an ablation depth only slightly larger than the thickness of the multilayer magnetic film. Further increase of the pulse number does not result in deeper ablation. However, 770-nm ripples become parallel to the polarization and are swelling to more than 120 nm above zero, much more than the full multilayer film thickness. In the spot periphery, much shallower 300-nm ripples are perpendicular to the strong modulation and the laser polarization. Irradiation with 0.49-J/cm2 pulses from an ultrafast white-light continuum results—in the spot periphery—in the formation of 200-nm ripples, only swelling above zero after removal of the polymer cover, without digging into the magnetic film.

  15. New nanostructured materials: synthesis of dodecanuclear Ni(II) complexes and surface deposition studies.

    Science.gov (United States)

    Pons-Balagué, Alba; Piligkos, Stergios; Teat, Simon J; Sánchez Costa, Jose; Shiddiq, Muhandis; Hill, Stephen; Castro, German R; Ferrer-Escorihuela, Pilar; Sañudo, E Carolina

    2013-07-01

    Microwave-assisted synthesis has been used to obtain the family of dodecanuclear Ni(II) complexes [Ni12(NO3)(MeO)12(MeC6H4CO2)9(MeOH)10(H2O)2][ClO4]2 (1), [Ni12(NO3)(MeO)12(BrC6H4CO2)9(MeOH)10(H2O)2][ClO4]2 (2), [Ni12(CO3)(MeO)12(MeC6H4CO2)9(MeOH)10(H2O)2]2[SO4] (3) and [Ni12(NO3)(MeO)12(MeC6H4CO2)9(MeOH)8(H2O)7][NO3]2 (4). They contain three {Ni4O4} cubane units which template around a central μ6 anion, either NO3(-) or CO3(2-). Their magnetic properties have been studied by superconducting quantum interference device (SQUID) magnetometry and high-field EPR measurements. The nanostructuration of the Ni12 species on mica surfaces is studied by AFM and grazing-incidence X-ray diffraction, which reveal the formation of polycrystalline thin layers.

  16. Re-Inversion of Surface Electrical Resistivity Tomography Data from the Hanford Site B-Complex

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Timothy C.; Wellman, Dawn M.

    2013-05-01

    This report documents the three-dimensional (3D) inversion results of surface electrical resistivity tomography (ERT) data collected over the Hanford Site B-Complex. The data were collected in order to image the subsurface distribution of electrically conductive vadose zone contamination resulting from both planned releases of contamination into subsurface infiltration galleries (cribs, trenches, and tile fields), as well as unplanned releases from the B, BX, and BY tank farms and/or associated facilities. Electrically conductive contaminants are those which increase the ionic strength of pore fluids compared to native conditions, which comprise most types of solutes released into the subsurface B-Complex. The ERT data were collected and originally inverted as described in detail in report RPP-34690 Rev 0., 2007, which readers should refer to for a detailed description of data collection and waste disposal history. Although the ERT imaging results presented in that report successfully delineated the footprint of vadose zone contamination in areas outside of the tank farms, imaging resolution was not optimized due to the inability of available inversion codes to optimally process the massive ERT data set collected at the site. Recognizing these limitations and the potential for enhanced ERT characterization and time-lapse imaging at contaminated sites, a joint effort was initiated in 2007 by the U.S. Department of Energy – Office of Science (DOE-SC), with later support by the Office of Environmental Management (DOE-EM), and the U.S. Department of Defense (DOD), to develop a high-performance distributed memory parallel 3D ERT inversion code capable of optimally processing large ERT data sets. The culmination of this effort was the development of E4D (Johnson et al., 2010,2012) In 2012, under the Deep Vadose Zone Applied Field Research Initiative (DVZ-AFRI), the U.S. Department of Energy – Richland Operations Office (DOE-RL) and CH2M Hill Plateau Remediation

  17. Engineering the cell surface display of cohesins for assembly of cellulosome-inspired enzyme complexes on Lactococcus lactis

    Directory of Open Access Journals (Sweden)

    Wieczorek Andrew S

    2010-09-01

    Full Text Available Abstract Background The assembly and spatial organization of enzymes in naturally occurring multi-protein complexes is of paramount importance for the efficient degradation of complex polymers and biosynthesis of valuable products. The degradation of cellulose into fermentable sugars by Clostridium thermocellum is achieved by means of a multi-protein "cellulosome" complex. Assembled via dockerin-cohesin interactions, the cellulosome is associated with the cell surface during cellulose hydrolysis, forming ternary cellulose-enzyme-microbe complexes for enhanced activity and synergy. The assembly of recombinant cell surface displayed cellulosome-inspired complexes in surrogate microbes is highly desirable. The model organism Lactococcus lactis is of particular interest as it has been metabolically engineered to produce a variety of commodity chemicals including lactic acid and bioactive compounds, and can efficiently secrete an array of recombinant proteins and enzymes of varying sizes. Results Fragments of the scaffoldin protein CipA were functionally displayed on the cell surface of Lactococcus lactis. Scaffolds were engineered to contain a single cohesin module, two cohesin modules, one cohesin and a cellulose-binding module, or only a cellulose-binding module. Cell toxicity from over-expression of the proteins was circumvented by use of the nisA inducible promoter, and incorporation of the C-terminal anchor motif of the streptococcal M6 protein resulted in the successful surface-display of the scaffolds. The facilitated detection of successfully secreted scaffolds was achieved by fusion with the export-specific reporter staphylococcal nuclease (NucA. Scaffolds retained their ability to associate in vivo with an engineered hybrid reporter enzyme, E. coli β-glucuronidase fused to the type 1 dockerin motif of the cellulosomal enzyme CelS. Surface-anchored complexes exhibited dual enzyme activities (nuclease and β-glucuronidase, and were

  18. Ab-Initio Modelling Of Surface Site Reactivity And Fluid Transport In Clay Minerals Case Study: Pyrophyllite

    Energy Technology Data Exchange (ETDEWEB)

    Churakov, S.V

    2005-03-01

    Pyrophyllite, Al{sub 2}[Si{sub 4}O{sub 10}](OH){sub 2}, is the simplest structural prototype for 2:1 dioctahedral phyllosilicate. Because the net electric charge in pyrophyllite is zero, it is the best candidate for investigating the non electrostatic contribution to sorption and transport phenomena in clays. Using ab-initio simulations, we have investigated the reactivity and structure of the water-solid interface on the basal plane and edge sites of pyrophyllite. The calculations predict slightly hydrophobic behaviour of the basal plane. For the high water coverage (100), (110) and (-110), lateral facets have a lower energy than for the (010), (130) and (-130) surfaces. Analysis of the surface reactivity reveals that the =Al-OH groups are most easily protonated on the (010), (130) and (-130) facets. The =Al-O-Si= sites will be protonated on the (100), (130), (110), (-110) and (-130) surfaces. The =Al-OH{sub 2} complexes are more easily de-protonated than the =Si-OH and =Al-OH sites. A spontaneous, reversible exchange of the protons between the solution and the edge sites has been observed in ab-initio molecular dynamics simulations at 300 K. Such near-surface proton diffusion may result in a significant contribution to the diffusion coefficients measured in neutron scattering experiments. (author)

  19. From certain minimal surfaces in the 5-sphere to minimal Lagrangian submanifolds of the 3-dimensional complex projective space

    NARCIS (Netherlands)

    Bolton, J.; Scharlach, C.; Vrancken, L.

    2001-01-01

    In a previous paper it was shown how to associate with a Lagrangian submanifold satisfying Chen's equality in 3-dimensional complex projective space, a minimal surface in the 5-sphere with ellipse of curvature is a circle. In this paper we focus on the reverse construction.

  20. Reduction of protein adsorption on silica and polystyrene surfaces due to coating with Complex Coacervate Core Micelles

    NARCIS (Netherlands)

    Brzozowska, A. M.; Hofs, B.; de Keizer, A.; Fokkink, R.; Stuart, Martien A. Cohen; Norde, W.

    2009-01-01

    The reduction of protein adsorption by a polymer brush formed upon adsorption of Complex Coacervate Core Micelles (C3Ms), consisting of a charged copolymer containing a neutral block and an oppositely charged homopolymer, on silica and polystyrene surfaces has been studied in situ using fixed angle

  1. A novel Pfs38 protein complex on the surface of Plasmodium falciparum blood-stage merozoites

    DEFF Research Database (Denmark)

    Paul, Gourab; Deshmukh, Arunaditya; Kaur, Inderjeet

    2017-01-01

    and glycerol density gradient fractionation were carried out to confirm the respective interactions. Furthermore, erythrocyte binding assay with 6-cys proteins were undertaken to find out their possible role in host-parasite infection and seropositivity was assessed using Indian and Liberian sera. RESULTS...... the development of a multi-sub-unit malaria vaccine based on some of these protein complexes on merozoite surface....

  2. Integrating seasonal optical and thermal infrared spectra to characterize urban impervious surfaces with extreme spectral complexity: a Shanghai case study

    Science.gov (United States)

    Wang, Wei; Yao, Xinfeng; Ji, Minhe

    2016-01-01

    Despite recent rapid advancement in remote sensing technology, accurate mapping of the urban landscape in China still faces a great challenge due to unusually high spectral complexity in many big cities. Much of this complication comes from severe spectral confusion of impervious surfaces with polluted water bodies and bright bare soils. This paper proposes a two-step land cover decomposition method, which combines optical and thermal spectra from different seasons to cope with the issue of urban spectral complexity. First, a linear spectral mixture analysis was employed to generate fraction images for three preliminary endmembers (high albedo, low albedo, and vegetation). Seasonal change analysis on land surface temperature induced from thermal infrared spectra and coarse component fractions obtained from the first step was then used to reduce the confusion between impervious surfaces and nonimpervious materials. This method was tested with two-date Landsat multispectral data in Shanghai, one of China's megacities. The results showed that the method was capable of consistently estimating impervious surfaces in highly complex urban environments with an accuracy of R2 greater than 0.70 and both root mean square error and mean average error less than 0.20 for all test sites. This strategy seemed very promising for landscape mapping of complex urban areas.

  3. Molecular statics calculations of proton binding to goethite surfaces: A new approach to estimation of stability constants for multisite surface complexation models

    Science.gov (United States)

    Rustad, James R.; Felmy, Andrew R.; Hay, Benjamin P.

    1996-05-01

    A new approach to estimating stability constants for proton binding in multisite surface complexation models is presented. The method is based on molecular statics computation of energies for the formation of proton vacancies and interstitials in ideal periodic slabs representing the (100), (110), (010), (001), and (021) surfaces of goethite. Gas-phase energies of clusters representing the hydrolysis products of ferric iron are calculated using the same potential energy functions used for the surface. These energies are linearly related to the hydrolysis constants for ferric iron in aqueous solution. Stability constants for proton binding at goethite surfaces are estimated by assuming the same log K- Δ E relationship for goethite surface protonation reactions. These stability constants predict a pH of zero charge of 8.9, in adequate agreement with measurements on CO 2-free goethite. The estimated stability constants differ significantly from previous estimations based on Pauling bond strength. We find that nearly all the surface oxide ions are reactive; nineteen of the twenty-six surface sites investigated have log Kint between 7.7 and 9.4. This implies a site density between fifteen and sixteen reactive sites/nm for crystals dominated by (110) and (021) crystal faces.

  4. Using object-based analysis to derive surface complexity information for improved filtering of airborne laser scanning data

    Science.gov (United States)

    Yan, Menglong; Blaschke, Thomas; Tang, Hongzhao; Xiao, Chenchao; Sun, Xian; Zhang, Daobing; Fu, Kun

    2017-03-01

    Airborne laser scanning (ALS) is a technique used to obtain Digital Surface Models (DSM) and Digital Terrain Models (DTM) efficiently, and filtering is the key procedure used to derive DTM from point clouds. Generating seed points is an initial step for most filtering algorithms, whereas existing algorithms usually define a regular window size to generate seed points. This may lead to an inadequate density of seed points, and further introduce error type I, especially in steep terrain and forested areas. In this study, we propose the use of objectbased analysis to derive surface complexity information from ALS datasets, which can then be used to improve seed point generation.We assume that an area is complex if it is composed of many small objects, with no buildings within the area. Using these assumptions, we propose and implement a new segmentation algorithm based on a grid index, which we call the Edge and Slope Restricted Region Growing (ESRGG) algorithm. Surface complexity information is obtained by statistical analysis of the number of objects derived by segmentation in each area. Then, for complex areas, a smaller window size is defined to generate seed points. Experimental results show that the proposed algorithm could greatly improve the filtering results in complex areas, especially in steep terrain and forested areas.

  5. Structure of DNA-Cationic Surfactant Complexes at Hydrophobically Modified and Hydrophilic Silica Surfaces as Revealed by Neutron Reflectometry

    DEFF Research Database (Denmark)

    Cardenas Gomez, Marite; Wacklin, Hanna; Campbell, Richard A.

    2011-01-01

    In this article, we discuss the structure and composition of mixed DNA-cationic surfactant adsorption layers on both hydrophobic and hydrophilic solid surfaces. We have focused on the effects of the bulk concentrations, the surfactant chain length, and the type solid surface on the interfacial...... layer structure (the location, coverage, and conformation the e DNA and surfactant molecules). Neutron reflectometry is the technique of choice for revealing the surface layer structure by means of selective deuteration. We start by studying the interfacial complexation of DNA...... with dodecyltrimethylammonium bromide (DTAB) and hexadecyltrimethylammonium bromide (CTAB) on hydrophobic surfaces, where we show that DNA molecules are located on top of a self-assembled surfactant monolayer, with the thickness of the DNA layer and the surfactant DNA ratio determined by the surface coverage of the underlying...

  6. Molecular and electronic structure of osmium complexes confined to Au(111) surfaces using a self-assembled molecular bridge

    Energy Technology Data Exchange (ETDEWEB)

    Llave, Ezequiel de la; Herrera, Santiago E.; Adam, Catherine; Méndez De Leo, Lucila P.; Calvo, Ernesto J.; Williams, Federico J., E-mail: fwilliams@qi.fcen.uba.ar [INQUIMAE-CONICET, Departamento de Química Inorgánica, Analítica y Química-Física, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, Buenos Aires C1428EHA (Argentina)

    2015-11-14

    The molecular and electronic structure of Os(II) complexes covalently bonded to self-assembled monolayers (SAMs) on Au(111) surfaces was studied by means of polarization modulation infrared reflection absorption spectroscopy, photoelectron spectroscopies, scanning tunneling microscopy, scanning tunneling spectroscopy, and density functional theory calculations. Attachment of the Os complex to the SAM proceeds via an amide covalent bond with the SAM alkyl chain 40° tilted with respect to the surface normal and a total thickness of 26 Å. The highest occupied molecular orbital of the Os complex is mainly based on the Os(II) center located 2.2 eV below the Fermi edge and the LUMO molecular orbital is mainly based on the bipyridine ligands located 1.5 eV above the Fermi edge.

  7. Interacting resonances in the F+H2 reaction revisited: complex terms, Riemann surfaces, and angular distributions.

    Science.gov (United States)

    Sokolovski, D; Sen, S K; Aquilanti, V; Cavalli, S; De Fazio, D

    2007-02-28

    We study the effect of overlapping resonances on the angular distributions of the reaction F+H2(v=0,j=0)-->HF(v=2,j=0)+H in the collision energy range from 5 to 65 meV, i.e., under the reaction barrier. Reactive scattering calculations were performed using the hyperquantization algorithm on the potential energy surface of Stark and Werner [J. Chem. Phys. 104, 6515 (1996)]. The positions of the Regge and complex energy poles are obtained by Pade reconstruction of the scattering matrix element. The Sturmian theory is invoked to relate the Regge and complex energy terms. For two interacting resonances, a two-sheet Riemann surface is contracted and inverted. The semiclassical complex angular momentum analysis is used to decompose the scattering amplitude into the direct and resonance contributions.

  8. Supported organometallic complexes: Surface chemistry, spectroscopy, and catalysis. Progress report, March 15, 1988--July 14, 1989

    Energy Technology Data Exchange (ETDEWEB)

    Marks, T.J.

    1990-02-01

    The goal of our program is to define those modes of interaction that take place between organometallic molecules and inorganic surfaces and, ultimately, to correlate various molecule-surface structures with catalytic properties.

  9. Surface complexation modeling of U(VI) sorption on TiO{sub 2} in the presence of fulvic acid

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Yuanlv [Ministry of Environmental Protection, Beijing (China). Nuclear and Radiation Safety Center; Univ. Lanzhou (China). Radiochemistry Lab.; Qiao, Yahua; Wang, Liang; Liu, Fudong; Zhang, Chunming [Ministry of Environmental Protection, Beijing (China). Nuclear and Radiation Safety Center; Guo, Zhijun; Wu, Wangsuo [Univ. Lanzhou (China). Radiochemistry Lab.

    2016-05-01

    In this work, experiments and modeling for the interactions between uranyl ion and TiO{sub 2} in the presence of fulvic acid are presented. The results demonstrated that FA is strongly bound to TiO{sub 2}, and these molecules have a very large effect on the U(VI) sorption, and vice versa. The results also demonstrated that U(VI) sorption to TiO{sub 2} in the presence and absence of sorbed FA can be well predicted with the SCD model (surface and complex distribution). According to the model calculations, the nature of the interactions between FA with U(VI) at TiO{sub 2} surface is mainly surface complex and electrostatic potential.

  10. Physical Studies of Some Hydrazinobenzoic Acid Complexes

    Institute of Scientific and Technical Information of China (English)

    M.G.Abd El Wahed; S.Abd El Wanees; M. El Gamel; S.Abd El Haleem

    2005-01-01

    The stability constants of complexes of 2-hydrazinobenzoic acid and 4-hydrazinobenzoic acid with Ni (Ⅱ), Cu (Ⅱ),Zn (Ⅱ), Cd (Ⅱ), and Hg (Ⅱ) were determined potentiometrically at different temperatures. The thermodynamic parameters,△AG°,△AH°, and △S° were calculated and proved that the complexation process is spontaneous and endothermic. The thermodynamic functions were analyzed in terms of electrostatic and non-electrostatic components and the results reveal that ionic bonds are formed between the studied ligands and metal ions. Conductometric titration was shown that the stoichiometry of the formed complexes are M:L and M:2L. The structure of the prepared solid complexes was characterized using IR, 1H NMR, 13C NMR spectroscopies as well as X-ray diffraction technique.Finally electrical conductivity of the ligands and their copper complexes was measured and shown that the ligands have a semiconductor behaviour.

  11. Optimal Parameter and Uncertainty Estimation of a Land Surface Model: Sensitivity to Parameter Ranges and Model Complexities

    Institute of Scientific and Technical Information of China (English)

    Youlong XIA; Zong-Liang YANG; Paul L. STOFFA; Mrinal K. SEN

    2005-01-01

    Most previous land-surface model calibration studies have defined global ranges for their parameters to search for optimal parameter sets. Little work has been conducted to study the impacts of realistic versus global ranges as well as model complexities on the calibration and uncertainty estimates. The primary purpose of this paper is to investigate these impacts by employing Bayesian Stochastic Inversion (BSI)to the Chameleon Surface Model (CHASM). The CHASM was designed to explore the general aspects of land-surface energy balance representation within a common modeling framework that can be run from a simple energy balance formulation to a complex mosaic type structure. The BSI is an uncertainty estimation technique based on Bayes theorem, importance sampling, and very fast simulated annealing.The model forcing data and surface flux data were collected at seven sites representing a wide range of climate and vegetation conditions. For each site, four experiments were performed with simple and complex CHASM formulations as well as realistic and global parameter ranges. Twenty eight experiments were conducted and 50 000 parameter sets were used for each run. The results show that the use of global and realistic ranges gives similar simulations for both modes for most sites, but the global ranges tend to produce some unreasonable optimal parameter values. Comparison of simple and complex modes shows that the simple mode has more parameters with unreasonable optimal values. Use of parameter ranges and model complexities have significant impacts on frequency distribution of parameters, marginal posterior probability density functions, and estimates of uncertainty of simulated sensible and latent heat fluxes.Comparison between model complexity and parameter ranges shows that the former has more significant impacts on parameter and uncertainty estimations.

  12. Estimation of surface energy fluxes under complex terrain of Mt. Qomolangma over the Tibetan Plateau

    NARCIS (Netherlands)

    Chen, Xuelong; Su, Zhongbo; Ma, Y.; Yang, K.; Wang, B.

    2013-01-01

    Surface solar radiation is an important parameter in surface energy balance models and in estimation of evapotranspiration. This study developed a DEM based radiation model to estimate instantaneous clear sky solar radiation for surface energy balance system to obtain accurate energy absorbed by the

  13. Loading antifungal drugs onto silica particles grafted with cyclodextrins by means of inclusion complex formation at the solid surface.

    Science.gov (United States)

    Hbaieb, Souhaira; Kalfat, Rafik; Chevalier, Yves

    2012-12-15

    Immobilization of antifungal drugs to solid particles has been addressed in order to limit the skin penetration to the skin surface during topical administration. Antifungal drug griseofulvin has been immobilized at the surface of silica particles by formation of its inclusion complex with β-cyclodextrins grafted to silica. A simple and fast process for loading griseofulvin into the hydrophobic cavity of cyclodextrins at the surface of the solid particles in aqueous suspension has been designed. It allowed the formation of the griseofulvin:cyclodextrin inclusion complex of 1:1 stoichiometry to completion. Grafting β-cyclodextrins to silica surface has been performed in a two-step procedure. The coupling agent 3-amino-propylmethyldiethoxysilane was reacted onto fumed silica particles as a first step. The second step was the reaction of grafted primary amino groups with tosylated β-cyclodextrin that led to β-cyclodextrin grafted silica. Loading griseofulvin onto grafted silica particles have been investigated by IR spectroscopy and by tracking possible crystals of griseofulvin in aqueous suspension by optical and scanning electron microscopy and X-ray diffraction. Successful formation of the inclusion complex at the surface of grafted silica suggested a strong adsorption of griseofulvin by means of heterogeneous nucleation of crystals, followed by inclusion complexation taking place between the partners being in close proximity at the surface of silica particles. The high adsorption capacity of CD-grafted silica for griseofulvin compared to bare silica and amino-grafted silica supports this interpretation. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Baculovirus Per Os Infectivity Factors Form a Complex on the Surface of Occlusion-Derived Virus ▿

    Science.gov (United States)

    Peng, Ke; van Oers, Monique M.; Hu, Zhihong; van Lent, Jan W. M.; Vlak, Just M.

    2010-01-01

    Five highly conserved per os infectivity factors, PIF1, PIF2, PIF3, PIF4, and P74, have been reported to be essential for oral infectivity of baculovirus occlusion-derived virus (ODV) in insect larvae. Three of these proteins, P74, PIF1, and PIF2, were thought to function in virus binding to insect midgut cells. In this paper evidence is provided that PIF1, PIF2, and PIF3 form a stable complex on the surface of ODV particles of the baculovirus Autographa californica multinucleocapsid nucleopolyhedrovirus (AcMNPV). The complex could withstand 2% SDS-5% β-mercaptoethanol with heating at 50°C for 5 min. The complex was not formed when any of the genes for PIF1, PIF2, or PIF3 was deleted, while reinsertion of these genes into AcMNPV restored the complex. Coimmunoprecipitation analysis independently confirmed the interactions of the three PIF proteins and revealed in addition that P74 is also associated with this complex. However, deletion of the p74 gene did not affect formation of the PIF1-PIF2-PIF3 complex. Electron microscopy analysis showed that PIF1 and PIF2 are localized on the surface of the ODV with a scattered distribution. This distribution did not change for PIF1 or PIF2 when the gene for PIF2 or PIF1 protein was deleted. We propose that PIF1, PIF2, PIF3, and P74 form an evolutionarily conserved complex on the ODV surface, which has an essential function in the initial stages of baculovirus oral infection. PMID:20610731

  15. Phosphate adsorption onto hematite: an in situ ATR-FTIR investigation of the effects of pH and loading level on the mode of phosphate surface complexation.

    Science.gov (United States)

    Elzinga, Evert J; Sparks, Donald L

    2007-04-01

    Phosphate adsorption on hematite was characterized as a function of pH (3.5-8.9) and phosphate concentration (5-500 microM) by in situ ATR-FTIR spectroscopy. Under most conditions a mixture of different (inner-sphere) phosphate complexes existed at the hematite surface, with the relative importance of these complexes varying with pH and surface coverage. Experiments using D(2)O and H(2)O indicated the presence of two protonated phosphate surface complexes at pH/pD=3.5-7.0. Comparison to spectra of protonated aqueous phosphate species suggested that these surface complexes are monoprotonated. The difference in the IR spectra of these complexes is tentatively interpreted to result from a different surface coordination, with one surface complex coordinated in a monodentate binuclear (bridging) fashion, and the second as a monodentate mononuclear complex. Alternatively, the bridging complex may be a (protonated) monodentate mononuclear complex exhibiting strong hydrogen bonding to an adjacent surface site, and the second species a monodentate complex exhibiting limited hydrogen bonding. Formation of the bridging complex is favored at lower pH values and higher surface loadings in the 3.5-7.0 pH range. At the highest pH values studied (8.5-9.0) a third complex, interpreted to be a nonprotonated monodentate mononuclear complex, is present along with the monodentate monoprotonated surface species. The importance of the nonprotonated monodentate complex increases with increasing surface coverage at these high pH values.

  16. Synthesis of trimethoprim metal complexes: Spectral, electrochemical, thermal, DNA-binding and surface morphology studies.

    Science.gov (United States)

    Demirezen, Nihat; Tarınç, Derya; Polat, Duygu; Ceşme, Mustafa; Gölcü, Ayşegül; Tümer, Mehmet

    2012-08-01

    Complexes of trimethoprim (TMP), with Cu(II), Zn(II), Pt(II), Ru(III) and Fe(III) have been synthesized. Then, these complexes have been characterized by spectroscopic techniques involving UV-vis, IR, mass and (1)H NMR. CHN elemental analysis, electrochemical and thermal behavior of complexes have also been investigated. The electrochemical properties of all complexes have been investigated by cyclic voltammetry (CV) using glassy carbon electrode. The biological activity of the complexes has been evaluated by examining their ability to bind to calf-thymus DNA (CT DNA) with UV spectroscopy and cyclic voltammetry. UV studies of the interaction of the complexes with DNA have shown that these compounds can bind to CT DNA. The binding constants of the complexes with CT DNA have also been calculated. The cyclic voltammograms of the complexes in the presence of CT DNA have shown that the complexes can bind to CT DNA by both the intercalative and the electrostatic binding mode. The antimicrobial activity of these complexes has been evaluated against three Gram-positive and four Gram-negative bacteria. Antifungal activity against two different fungi has been evaluated and compared with the reference drug TMP. Almost all types of complexes show excellent activity against all type of bacteria and fungi. The morphology of the CT DNA, TMP, metal ions and metal complexes has been investigated by scanning electron microscopy (SEM). To get the SEM images, the interaction of compounds with CT DNA has been studied by means of differential pulse voltammetry (DPV) at CT DNA modified pencil graphite electrode (PGE). The decrease in intensity of the guanine oxidation signals has been used as an indicator for the interaction mechanism.

  17. Photocatalytic reaction kinetics model based on electrical double layer theory Ⅲ.Surface complexation model of methyl orange adsorption on TiO2 surface

    Institute of Scientific and Technical Information of China (English)

    李新军; 李芳柏; 古国榜; 柳松; 王良焱; 梁园园

    2003-01-01

    Based on the infrared characterization of methyl orange adsorption on TiO2 surface and the titration of TiO2, the triple layer model of methyl orange adsorption on TiO2 was established according to electric double theory. The software FITEQL3.1 was applied to calculate the distribution of organic adsorption on TiO2 surface by introducing dummy components to help to overcome mathematical difficulties. It is shown that the chem. -adsorption species of methyl orange have a great adsorption amount. The adsorption constants of three kinds of surface complexation expressed as SOH+org-,SOH2org2 and SOHorg- are 5.98, 17.57 and -4.2, respectively.

  18. Planification de trajectoires pour placement automatise de fibres sur surfaces de geometries complexes

    Science.gov (United States)

    Hely, Clement

    During the past 50 years, the use of composite materials drastically increase, mainly thanks to the interest of aeronautical industries for these strong and lightweight materials. To improve the productivity of composite materials manufacturing some of the largest aeronautics companies began to develop automated processes such as Automated Fibre Placement (AFP). The AFP workcells currently used by the industry were mainly developed for production of large, nearly flat, plates with low curvatures such as aircraft fuselages. However, the fields of aeronautics and sport goods production begin nowadays to show an interest for manufacturing of smaller and more complex parts. The aim of the project in which this research takes place is to design a new AFP workcell and to develop new techniques allowing production of parts with small size and complex geometry. The work presented in this thesis focuses on the path planning on multi-axial revolution surfaces, e.g. Y-shaped tubes of constant circular cross section. Several path planning algorithms will be presented aiming at the exhaustive coverage of a mandrel with pre-impregnated (prepreg) composite tape. The methodology used in two of these algorithms is to individually cover each branch of the Y-shaped part with paths deriving from a helix. In the first one, the helix will be cut at the boundary between a branch and the junction region (algorithm HD) while in the second (algorithm HA) the pseudo-helix path can be adjusted to follow this boundary. These two methods were shown to have some drawbacks compromising their practical use and possibly leading to parts with diminished mechanical properties. To avoid these drawbacks, two others algorithms were developed with a new methodology. With them, the aim is to cover two branches of the Y-shape with a continuous course (i.e. without cut). The first one uses a well known strategy which defines plies with a constant fibre orientation. Parallel paths are then computed to

  19. Surface-complex films of guanidine on tantalum nitride electrochemically characterized for applications in chemical mechanical planarization

    Energy Technology Data Exchange (ETDEWEB)

    Rock, S.E.; Crain, D.J. [Department of Physics, Clarkson University, Potsdam, NY 13699-5820 (United States); Pettit, C.M. [Department of Physics, Emporia State University, Emporia, KS 66801-5087 (United States); Roy, D., E-mail: samoy@clarkson.edu [Department of Physics, Clarkson University, Potsdam, NY 13699-5820 (United States)

    2012-01-31

    Chemical mechanical planarization (CMP) of tantalum nitride is an essential step of material processing in the fabrication of integrated circuits. This CMP step often involves the chemical formation of a structurally weak oxide-complex film on the wafer surface, followed by selective removal of the film with mechanical abrasion under reduced loading. The present work investigates certain chemical aspects of this strategy of TaN-CMP by using guanidine carbonate (GC) as a surface complexing agent, and employing electrochemical experiments. The experiments are designed to study the chemical and electrochemical origins of the CMP-specific surface complex films formed on a TaN wafer in acidic solutions of GC and hydrogen peroxide. Open circuit potential, polarization resistance, and electrochemical impedance measurements are employed to probe the surface effects that facilitate material removal in chemically prevailing CMP of TaN. The results are discussed in view of designing slurry variables to support barrier layer planarization with reduced roles of mechanical abrasion.

  20. Guest-Host Complex Formed between Ascorbic Acid and β-Cyclodextrin Immobilized on the Surface of an Electrode

    Directory of Open Access Journals (Sweden)

    María Teresa Ramírez-Silva

    2014-05-01

    Full Text Available This work deals with the formation of supramolecular complexes between ascorbic acid (AA, the guest, and β-cyclodextrin (β-CD, the host, that was first potentiodynamically immobilized on the surface of a carbon paste electrode (CPE throughout the formation of a β-CD-based conducting polymer (poly-β-CD. With the bare CPE and the β-CD-modified CPE, an electrochemical study was performed to understand the effect of such surface modification on the electrochemical response of the AA. From this study it was shown that on the modified-CPE, the AA was surface-immobilized through formation of an inclusion complex with β-CD, which provoked the adsorption of AA in such a way that this stage became the limiting step for the electrochemical oxidation of AA. Moreover, from the analysis of the experimental voltammetric plots recorded during AA oxidation on the CPE/poly-β-CD electrode surfaces, the Gibbs’ standard free energy of the inclusion complex formed by the oxidation product of AA and β-CD has been determined for the first time, ∆G0inclus = −36.4 kJ/mol.

  1. Octahedral Ni(II) complex with new NNO donor Schiff base ligand: Synthesis, structure and Hirshfeld surface

    Science.gov (United States)

    Jana, Kalyanmoy; Maity, Tithi; Chandra Debnath, Subhas; Samanta, Bidhan Chandra; Seth, Saikat Kumar

    2017-02-01

    A new mononuclear Schiff base octahedral Ni(II) complex of general formula [NiII(L)2] has been synthesized using a new NNO donor Schiff base ligand (HL = 2-[(piperidin-2-ylmethylimino)-methyl]-phenol). The title complex has been characterized by various physical measurements such as elemental analyses, FT-IR, 1H NMR and UV-Vis spectroscopic techniques. The molecular structure of the title complex was determined by single crystal X-ray diffraction technique. The title complex is a mononuclear bis-ligand complex showing distorted octahedral geometry around nickel (II). X-ray crystallography reveals that the complex exhibits extensive supramolecular interactions in the solid-state. Two types of non-covalent interactions namely, π-π and C-H···π interactions are found to govern final solid-state architecture in the complex. The contribution of each interaction to the formation of the self-assembly has been analyzed through Hirshfeld surface calculation which enables quantitative contributions to the crystal packing in a novel visual manner.

  2. Surface modification of cellulose fiber via supramolecular assembly of biodegradable polyesters by the aid of host-guest inclusion complexation.

    Science.gov (United States)

    Zhao, Qiang; Wang, Shufang; Cheng, Xinjian; Yam, Richard C M; Kong, Deling; Li, Robert K Y

    2010-05-10

    In this article, we report a novel surface modification method for cellulose fiber that is based on supramolecular assembly. Beta-cyclodextrin (beta-CD) was first covalently grafted onto the fiber surface. Then poly(epsilon-caprolactone) (PCL) oligomers having both ends capped with adamantane motifs (i.e., PCL-AD) were immobilized to the cellulose fiber surface through the host-guest inclusion complexation between beta-CD and AD motif. FTIR-ATR and XPS analyses confirmed the successful assembly of PCL-ADs, which was further supported by the increasing trend of weight gain with the concentration of CDs on the fiber surface. Contact angle and TGA measurements reflect the enhanced hydrophobicity and thermal stability of the cellulose fiber as a consequence of this modification. The morphologies of the cellulose fiber before and after the assembly process have also been compared by SEM.

  3. Investigate the complex process in particle-fluid based surface generation technology using reactive molecular dynamics method

    Science.gov (United States)

    Han, Xuesong; Li, Haiyan; Zhao, Fu

    2017-07-01

    Particle-fluid based surface generation process has already become one of the most important materials processing technology for many advanced materials such as optical crystal, ceramics and so on. Most of the particle-fluid based surface generation technology involves two key process: chemical reaction which is responsible for surface softening; physical behavior which is responsible for materials removal/deformation. Presently, researchers cannot give a reasonable explanation about the complex process in the particle-fluid based surface generation technology because of the small temporal-spatial scale and the concurrent influence of physical-chemical process. Molecular dynamics (MD) method has already been proved to be a promising approach for constructing effective model of atomic scale phenomenon and can serve as a predicting simulation tool in analyzing the complex surface generation mechanism and is employed in this research to study the essence of surface generation. The deformation and piles of water molecule is induced with the feeding of abrasive particle which justifies the property mutation of water at nanometer scale. There are little silica molecule aggregation or materials removal because the water-layer greatly reduce the strength of mechanical interaction between particle and materials surface and minimize the stress concentration. Furthermore, chemical effect is also observed at the interface: stable chemical bond is generated between water and silica which lead to the formation of silconl and the reaction rate changes with the amount of water molecules in the local environment. Novel ring structure is observed in the silica surface and it is justified to be favored of chemical reaction with water molecule. The siloxane bond formation process quickly strengthened across the interface with the feeding of abrasive particle because of the compressive stress resulted by the impacting behavior.

  4. Investigate the complex process in particle-fluid based surface generation technology using reactive molecular dynamics method

    Directory of Open Access Journals (Sweden)

    Xuesong Han

    2017-07-01

    Full Text Available Particle-fluid based surface generation process has already become one of the most important materials processing technology for many advanced materials such as optical crystal, ceramics and so on. Most of the particle-fluid based surface generation technology involves two key process: chemical reaction which is responsible for surface softening; physical behavior which is responsible for materials removal/deformation. Presently, researchers cannot give a reasonable explanation about the complex process in the particle-fluid based surface generation technology because of the small temporal-spatial scale and the concurrent influence of physical-chemical process. Molecular dynamics (MD method has already been proved to be a promising approach for constructing effective model of atomic scale phenomenon and can serve as a predicting simulation tool in analyzing the complex surface generation mechanism and is employed in this research to study the essence of surface generation. The deformation and piles of water molecule is induced with the feeding of abrasive particle which justifies the property mutation of water at nanometer scale. There are little silica molecule aggregation or materials removal because the water-layer greatly reduce the strength of mechanical interaction between particle and materials surface and minimize the stress concentration. Furthermore, chemical effect is also observed at the interface: stable chemical bond is generated between water and silica which lead to the formation of silconl and the reaction rate changes with the amount of water molecules in the local environment. Novel ring structure is observed in the silica surface and it is justified to be favored of chemical reaction with water molecule. The siloxane bond formation process quickly strengthened across the interface with the feeding of abrasive particle because of the compressive stress resulted by the impacting behavior.

  5. Internalization of cycloheptaamylose-dansyl chloride complex during labelling of surface membrane in living Paramecium aurelia cells.

    Science.gov (United States)

    Giordano, P A; Wyroba, E; Bottiroli, G

    1985-01-01

    Internalization of cycloheptaamylose-dansyl chloride complex during surface labelling of living long-term starved Paramecium aurelia cells has been observed. This process may be inhibited by pretreatment of the ciliates with dichloroisoproterenol. Uptake of cycloheptaamylose-dansyl chloride may be visualized only after UV preirradiation: the appearance of orange-fluorescing vacuoles of diameter 2.3-4.5 micron may then be observed. Microspectrographic analysis performed on the cells and dansyl derivatives indicates that this fluorescence is produced by a photochemical reaction of dansyl chloride - released from CDC complex inside the digestive vacuoles-under the influence of UV irradiation.

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

    Science.gov (United States)

    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

  7. Estimation of surface energy fluxes under complex terrain of Mt. Qomolangma over the Tibetan Plateau

    Directory of Open Access Journals (Sweden)

    X. Chen

    2013-04-01

    Full Text Available Surface solar radiation is an important parameter in surface energy balance models and in estimation of evapotranspiration. This study developed a DEM based radiation model to estimate instantaneous clear sky solar radiation for surface energy balance system to obtain accurate energy absorbed by the mountain surface. Efforts to improve spatial accuracy of satellite based surface energy budget in mountainous regions were made in this work. Based on eight scenes of Landsat TM/ETM+ (Thematic Mapper/Enhanced Thematic Mapper+ data and observations around the Qomolangma region of the Tibetan Plateau, the topographical enhanced surface energy balance system (TESEBS was tested for deriving net radiation, ground heat flux, sensible heat flux and latent heat flux distributions over the heterogeneous land surface. The land surface energy fluxes over the study area showed a wide range in accordance with the surface features and their thermodynamic states. The model was validated by observations at QOMS/CAS site in the research area with a reasonable accuracy. The mean bias of net radiation, sensible heat flux, ground heat flux and latent heat flux is lower than 23.6 W m−2. The surface solar radiation estimated by the DEM based radiation model developed by this study has a mean bias as low as −9.6 W m−2. TESEBS has a decreased mean bias of about 5.9 W m−2 and 3.4 W m−2 for sensible heat and latent heat flux, respectively, compared to the Surface Energy Balance System (SEBS.

  8. The weakly bound He-HCCCN complex: High-resolution microwave spectra and intermolecular potential-energy surface

    Science.gov (United States)

    Topic, Wendy C.; Jäger, Wolfgang

    2005-08-01

    Rotational spectra of the weakly bound He-HCCCN and He-DCCCN van der Waals complexes were observed using a pulsed-nozzle Fourier-transform microwave spectrometer in the 7-26-GHz frequency region. Nuclear quadrupole hyperfine structures due to the N14 and D nuclei (both with nuclear-spin quantum number I =1) were resolved and assigned. Both strong a and weaker b-type transitions were observed and the assigned transitions were used to fit the parameters of a distortable asymmetric rotor model. The dimers are floppy, near T-shaped complexes. Three intermolecular potential-energy surfaces were calculated using the coupled-cluster method with single and double excitations and noniterative inclusion of triple excitations. Bound-state rotational energy levels supported by these surfaces were determined. The quality of the potential-energy surfaces was assessed by comparing the experimental and calculated transition frequencies and also the corresponding spectroscopic parameters. Simple scaling of the surfaces improved both the transition frequencies and spectroscopic constants. Five other recently reported surfaces [O. Akin-Ojo, R. Bukowski, and K. Szalewicz, J. Chem. Phys. 119, 8379 (2003)], calculated using a variety of methods, and their agreement with spectroscopic properties of He-HCCCN are discussed.

  9. Hybrid Sol-Gel-Derived Films That Spontaneously Form Complex Surface Topographies.

    Science.gov (United States)

    Destino, Joel F; Jones, Zachary R; Gatley, Caitlyn M; Zhang, Yi; Craft, Andrew K; Detty, Michael R; Bright, Frank V

    2016-10-04

    Surface patterns over multiple length scales are known to influence various biological processes. Here we report the synthesis and characterization of new, two-component xerogel thin films derived from carboxyethylsilanetriol (COE) and tetraethoxysilane (TEOS). Atomic force microscopy (AFM) reveals films surface with branched and hyper branched architectures that are ∼2 to 30 μm in diameter, that extend ∼3 to 1300 nm above the film base plane with surface densities that range from 2 to 77% surface area coverage. Colocalized AFM and Raman spectroscopy show that these branched structures are COE-rich domains, which are slightly stiffer (as shown from phase AFM imaging) and exhibit lower capacitive force in comparison with film base plane. Raman mapping reveals there are also discrete domains (≤300 nm in diameter) that are rich in COE dimers and densified TEOS, which do not appear to correspond with any surface structure seen by AFM.

  10. The influence of CNC milling and ball burnishing on shaping complex 3D surfaces

    Science.gov (United States)

    Bachtiak-Radka, Emilia; Dudzińska, Sara; Grochała, Daniel; Berczyński, Stefan; Olszak, Wiesław

    2017-03-01

    Hybrid techniques for surface treatment should ensure compliance with exterior layer state and stress requirements. The more factors which influence final treatment effects, the more difficult it is to conduct a technological process combining different treatment methods. A combination of shaping milling with finishing burnishing can provide very good smoothness and satisfactory stress conditions. However, implementation of predefined geometric surface specifications (GPS) is very difficult. This article presents the results of the effect of technological parameters of both treatments combined into a single operation on surface topography. A new surface geometry evaluation approach, combining both relative and absolute changes of isotropy and surface roughness, enabling an objective efficiency comparison of machining operations combined in a single operation, is presented.

  11. The dynamics of the surface layer of lipid membranes doped by vanadium complex: computer modeling and EPR studies

    Directory of Open Access Journals (Sweden)

    Olchawa Ryszard

    2015-07-01

    Full Text Available Penetration of the liposome membranes doped with vanadium complex formed in the liquid-crystalline phase from egg yolk lecithin (EYL by the TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl spin probes has been investigated. The penetration process was followed by 360 hours at 24°C, using the electron spin resonance (EPR method. The spectroscopic parameter of the partition (F of this probe indicated that a maximum rigidity of the membrane was at 3% concentration of the vanadium complex. Computer simulations showed that the increase in the rigidity of the membrane corresponds to the closure of gaps in the surface layer of the membrane, and indicates the essential role of the membrane surface in transport processes.

  12. Surface-Induced Dissociation of Protein Complexes in a Hybrid Fourier Transform Ion Cyclotron Resonance Mass Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Jing; Zhou, Mowei; Gilbert, Joshua D.; Wolff, Jeremy J.; Somogyi, Árpád; Pedder, Randall E.; Quintyn, Royston S.; Morrison, Lindsay J.; Easterling, Michael L.; Paša-Tolić, Ljiljana; Wysocki, Vicki H.

    2017-01-03

    Mass spectrometry continues to develop as a valuable tool in the analysis of proteins and protein complexes. In protein complex mass spectrometry studies, surface-induced dissociation (SID) has been successfully applied in quadrupole time-of-flight (Q-TOF) instruments. SID provides structural information on non-covalent protein complexes that is complementary to other techniques. However, the mass resolution of Q-TOF instruments can limit the information that can be obtained for protein complexes by SID. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) provides ultrahigh resolution and ultrahigh mass accuracy measurements. In this study, an SID device was designed and successfully installed in a hybrid FT-ICR instrument in place of the standard gas collision cell. The SID-FT-ICR platform has been tested with several protein complex systems (homooligomers, a heterooligomer, and a protein-ligand complex, ranging from 53 kDa to 85 kDa), and the results are consistent with data previously acquired on Q-TOF platforms, matching predictions from known protein interface information. SID fragments with the same m/z but different charge states are well-resolved based on distinct spacing between adjacent isotope peaks, and the addition of metal cations and ligands can also be isotopically resolved with the ultrahigh mass resolution available in FT-ICR.

  13. Preparation and Analysis of Complex Barrier Layer of Heterocyclic and Long-Chain Organosilane on Copper Alloy Surface

    Directory of Open Access Journals (Sweden)

    Qian Zhao

    2016-07-01

    Full Text Available A single electrodeposited film of 6-(3-triethoxysilylpropylamino-1,3,5-triazine-2,4-dithiol monosodium (TES on a copper alloy surface was prepared by the galvanostatic method, then octyl-triethoxysilane (OTES or hexadecyl-trimethoxysilane (HDTMS was used to modify the electrodeposited film by the self-assembled technique to fabricate the complex film. The electrodeposition process was inferred by cyclic voltammetry. The single and complex films were characterized by means of contact angle, cyclic voltammetry, Fourier transform infrared spectroscopy (FT-IR, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS and scanning electron microscope (SEM. The results showed that the contact angle of the complex film covering the copper alloy surface was up to 118.1° compared with 89.4° of the bare copper alloy. The cyclic voltammogram, polarization curves and EIS indicated that the anti-corrosion performance of complex film was better than that of single electrodeposited TES film, and the protection efficiency was up to 90.2%.

  14. Fermi-surface reconstruction and complex phase equilibria in CaFe2As2.

    Science.gov (United States)

    Gofryk, K; Saparov, B; Durakiewicz, T; Chikina, A; Danzenbächer, S; Vyalikh, D V; Graf, M J; Sefat, A S

    2014-05-09

    Fermi-surface topology governs the relationship between magnetism and superconductivity in iron-based materials. Using low-temperature transport, angle-resolved photoemission, and x-ray diffraction, we show unambiguous evidence of large Fermi-surface reconstruction in CaFe2As2 at magnetic spin-density-wave and nonmagnetic collapsed-tetragonal (cT) transitions. For the cT transition, the change in the Fermi-surface topology has a different character with no contribution from the hole part of the Fermi surface. In addition, the results suggest that the pressure effect in CaFe2As2 is mainly leading to a rigid-band-like change of the valence electronic structure. We discuss these results and their implications for magnetism and superconductivity in this material.

  15. The complex dispersion relation of surface plasmon polaritons at gold/para-hexaphenylene interfaces

    DEFF Research Database (Denmark)

    Lemke, Christoph; Leißner, Till; Klick, Alwin;

    2014-01-01

    Two-photon photoemission electron microscopy (2P-PEEM) is used to measure the real and imaginary part of the dispersion relation of surface plasmon polaritons at different interface systems. A comparison of calculated and measured dispersion data for a gold/vacuum interface demonstrates the capab......Two-photon photoemission electron microscopy (2P-PEEM) is used to measure the real and imaginary part of the dispersion relation of surface plasmon polaritons at different interface systems. A comparison of calculated and measured dispersion data for a gold/vacuum interface demonstrates...... the capability of the presented experimental approach. A systematic 2P-PEEM study on the dispersion relation of dielectric-loaded gold surfaces shows how effective the propagation of surface plasmon polaritons at a gold/para-hexaphenylene interface can be tuned by adjustment of the dielectric film thickness...

  16. Profile Curvature Derivative Surface used to characterize the complexity of the seafloor around St. John, USVI

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Profile curvature was calculated from the bathymetry surface for each raster cell using the ArcGIS 3D Analyst "Curvature" Tool. Profile curvature describes the rate...

  17. Curvature Derivative Surface used to characterize the complexity of the seafloor around St. John, USVI

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Curvature was calculated from the bathymetry surface for each raster cell using the ArcGIS 3D Analyst "Curvature" Tool. Curvature describes the rate of change of...

  18. Plan Curvature Derivative Surface used to characterize the complexity of the seafloor around St. John, USVI

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Plan curvature was calculated from the bathymetry surface for each raster cell using the ArcGIS 3D Analyst "Curvature" Tool. Plan curvature describes the rate of...

  19. Fermi-Surface Reconstruction and Complex Phase Equilibria in CaFe2As2

    Science.gov (United States)

    Gofryk, K.; Saparov, B.; Durakiewicz, T.; Chikina, A.; Danzenbächer, S.; Vyalikh, D. V.; Graf, M. J.; Sefat, A. S.

    2014-05-01

    Fermi-surface topology governs the relationship between magnetism and superconductivity in iron-based materials. Using low-temperature transport, angle-resolved photoemission, and x-ray diffraction, we show unambiguous evidence of large Fermi-surface reconstruction in CaFe2As2 at magnetic spin-density-wave and nonmagnetic collapsed-tetragonal (cT) transitions. For the cT transition, the change in the Fermi-surface topology has a different character with no contribution from the hole part of the Fermi surface. In addition, the results suggest that the pressure effect in CaFe2As2 is mainly leading to a rigid-band-like change of the valence electronic structure. We discuss these results and their implications for magnetism and superconductivity in this material.

  20. In situ studies of complex PLD-grown films using hard X-ray surface diffraction

    Science.gov (United States)

    Willmott, P. R.; Schlepütz, C. M.; Patterson, B. D.; Herger, R.; Lange, M.; Meister, D.; Maden, D.; Brönnimann, Ch.; Eikenberry, E. F.; Hülsen, G.; Al-Adwan, A.

    2005-07-01

    A novel ultra-high vacuum chamber for growing films via pulsed laser deposition and studying the growth processes in situ using hard synchrotron radiation is presented. The chamber is mounted onto a 5-circle surface diffractometer and contains a large cylindrical-section beryllium window, which allows an extensive range of reciprocal space to be probed. The chamber is primarily used to perform surface diffraction measurements, for which much of the most valuable information derives from the weakest signals. With this in mind, we have employed a photon-counting area pixel detector system, which reduces data acquisition times by one to two orders of magnitude and concomitantly increases the potential volume of data that can be acquired for any given sample before the surface degrades due to surface contamination or radiation damage. Examples are presented of initial results obtained using this system.

  1. Slope Derivative Surface used to characterize the complexity of the seafloor around St. John, USVI

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Slope was calculated from the bathymetry surface for each raster cell using ArcGIS's Spatial Analyst 'Slope' Tool. Slope describes the maximum steepness of a terrain...

  2. Rugosity Derivative Surface used to characterize the complexity of the seafloor around St. John, USVI

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity was calculated from the bathymetry surface for each cell using the "Rugosity" function in the Benthic Terrain Modeler toolbox (Jenness 2002, 2004; Wright et...

  3. Bipodal surface organometallic complexes with surface N-donor ligands and application to the catalytic cleavage of C-H and C-C bonds in n -Butane

    KAUST Repository

    Bendjeriou-Sedjerari, Anissa

    2013-11-27

    We present a new generation of "true vicinal" functions well-distributed on the inner surface of SBA15: [(Sî - Si-NH 2)(≡Si-OH)] (1) and [(≡Si-NH2)2] (2). From these amine-modified SBA15s, two new well-defined surface organometallic species [(≡Si-NH-)(≡Si-O-)]Zr(CH2tBu) 2 (3) and [(≡Si-NH-)2]Zr(CH2tBu) 2 (4) have been obtained by reaction with Zr(CH2tBu) 4. The surfaces were characterized with 2D multiple-quantum 1H-1H NMR and infrared spectroscopies. Energy-filtered transmission electron microscopy (EFTEM), mass balance, and elemental analysis unambiguously proved that Zr(CH2tBu)4 reacts with these vicinal amine-modified surfaces to give mainly bipodal bis(neopentyl)zirconium complexes (3) and (4), uniformly distributed in the channels of SBA15. (3) and (4) react with hydrogen to give the homologous hydrides (5) and (6). Hydrogenolysis of n-butane catalyzed by these hydrides was carried out at low temperature (100 C) and low pressure (1 atm). While (6) exhibits a bis(silylamido)zirconium bishydride, [(≡Si-NH-)2]Zr(H) 2 (6a) (60%), and a bis(silylamido)silyloxozirconium monohydride, [(≡Si-NH-)2(≡Si-O-)]ZrH (6b) (40%), (5) displays a new surface organometallic complex characterized by an 1H NMR signal at 14.46 ppm. The latter is assigned to a (silylimido)(silyloxo)zirconium monohydride, [(≡Si-Nî)(≡Si-O-)]ZrH (5b) (30%), coexistent with a (silylamido)(silyloxo)zirconium bishydride, [(≡Si-NH-)(≡Si-O-)] Zr(H)2 (5a) (45%), and a silylamidobis(silyloxo)zirconium monohydride, [(≡Si-NH-)(≡Si-O-)2]ZrH (5c) (25%). Surprisingly, nitrogen surface ligands possess catalytic properties already encountered with silicon oxide surfaces, but interestingly, catalyst (5) with chelating [N,O] shows better activity than (6) with chelating [N,N]. © 2013 American Chemical Society.

  4. Modeling the Excess Cell Surface Stored in a Complex Morphology of Bleb-Like Protrusions

    Science.gov (United States)

    Wessler, Timothy; Yang, Xiaofeng; Chen, Alex; Roach, Nathan; Elston, Timothy C.; Wang, Qi; Jacobson, Ken; Forest, M. Gregory

    2016-01-01

    Cells transition from spread to rounded morphologies in diverse physiological contexts including mitosis and mesenchymal-to-amoeboid transitions. When these drastic shape changes occur rapidly, cell volume and surface area are approximately conserved. Consequently, the rounded cells are suddenly presented with a several-fold excess of cell surface whose area far exceeds that of a smooth sphere enclosing the cell volume. This excess is stored in a population of bleb-like protrusions (BLiPs), whose size distribution is shown by electron micrographs to be skewed. We introduce three complementary models of rounded cell morphologies with a prescribed excess surface area. A 2D Hamiltonian model provides a mechanistic description of how discrete attachment points between the cell surface and cortex together with surface bending energy can generate a morphology that satisfies a prescribed excess area and BLiP number density. A 3D random seed-and-growth model simulates efficient packing of BLiPs over a primary rounded shape, demonstrating a pathway for skewed BLiP size distributions that recapitulate 3D morphologies. Finally, a phase field model (2D and 3D) posits energy-based constitutive laws for the cell membrane, nematic F-actin cortex, interior cytosol, and external aqueous medium. The cell surface is equipped with a spontaneous curvature function, a proxy for the cell surface-cortex couple, that is a priori unknown, which the model “learns” from the thin section transmission electron micrograph image (2D) or the “seed and growth” model image (3D). Converged phase field simulations predict self-consistent amplitudes and spatial localization of pressure and stress throughout the cell for any posited stationary morphology target and cell compartment constitutive properties. The models form a general framework for future studies of cell morphological dynamics in a variety of biological contexts. PMID:27015526

  5. Modeling the Excess Cell Surface Stored in a Complex Morphology of Bleb-Like Protrusions.

    Directory of Open Access Journals (Sweden)

    Maryna Kapustina

    2016-03-01

    Full Text Available Cells transition from spread to rounded morphologies in diverse physiological contexts including mitosis and mesenchymal-to-amoeboid transitions. When these drastic shape changes occur rapidly, cell volume and surface area are approximately conserved. Consequently, the rounded cells are suddenly presented with a several-fold excess of cell surface whose area far exceeds that of a smooth sphere enclosing the cell volume. This excess is stored in a population of bleb-like protrusions (BLiPs, whose size distribution is shown by electron micrographs to be skewed. We introduce three complementary models of rounded cell morphologies with a prescribed excess surface area. A 2D Hamiltonian model provides a mechanistic description of how discrete attachment points between the cell surface and cortex together with surface bending energy can generate a morphology that satisfies a prescribed excess area and BLiP number density. A 3D random seed-and-growth model simulates efficient packing of BLiPs over a primary rounded shape, demonstrating a pathway for skewed BLiP size distributions that recapitulate 3D morphologies. Finally, a phase field model (2D and 3D posits energy-based constitutive laws for the cell membrane, nematic F-actin cortex, interior cytosol, and external aqueous medium. The cell surface is equipped with a spontaneous curvature function, a proxy for the cell surface-cortex couple, that is a priori unknown, which the model "learns" from the thin section transmission electron micrograph image (2D or the "seed and growth" model image (3D. Converged phase field simulations predict self-consistent amplitudes and spatial localization of pressure and stress throughout the cell for any posited stationary morphology target and cell compartment constitutive properties. The models form a general framework for future studies of cell morphological dynamics in a variety of biological contexts.

  6. Complex Wind-Induced Variations of Surface Snow Accumulation Rates over East Antarctica

    Science.gov (United States)

    Das, I.; Scambos, T. A.; Koenig, L.; van den Broeke, M.; Lenaerts, J.

    2015-12-01

    Accurate quantification of surface snow-accumulation over Antarctica is important for mass balance estimates and climate studies based on ice core records. Using airborne radar, lidar and thresholds of surface slope, modeled surface mass balance (SMB) and wind fields, we have predicted continent-wide distribution of wind-scour zones over Antarctica. These zones are located over relatively steep ice surfaces formed by ice flow over bedrock topography. Near-surface winds accelerate over these steeper slopes and erode and sublimate the snow. This results in numerous localized regions (typically ≤ 200 km2) with reduced or negative surface accumulation. Although small zones of re-deposition occur at the base of the steeper slope areas, the redeposited mass is small relative to the ablation loss. Total losses from wind-scour and wind-glaze areas amounts to tens of gigatons annually. Near the coast, winds often blow significant amounts of surface snow from these zones into the ocean. Large uncertainties remain in SMB estimates over East Antarctica as climate models do not adequately represent the small-scale physical processes that lead to mass loss or redistribution over the wind-scour zones. In this study, we also use Operation IceBridge's snow radar data to provide evidence for a gradual ablation of ~16-18 m of firn (~200 years of accumulation) from wind-scour zones over the upper Recovery Ice Stream catchment. The maximum ablation rates observed in this region are ~ -54 kg m-2 a-1 (-54 mm water equivalent a-1). Our airborne radio echo-sounding analysis show snow redeposition downslope of the wind-scour zones is <10% of the cumulative mass loss. Our study shows that the local mass loss is dominated by sublimation to water vapor rather than wind-transport of snow.

  7. Surface, morphology and X-ray diffraction studies of Co (II) complexes of pyrazole ligands

    Science.gov (United States)

    Mishra, A.; Jain, Garima; Ninama, S.

    2014-09-01

    Pyrazole based complexes of the cobalt (II) Bis-(diethyl 4-amino-1-(P-nitrophenyl) 1H-pyrazole-3,5dicarboxylate) [Co (D4A1(P-N)1HP35D)] and cobalt (II) Bis-(diethyl 4- amino-1-(3-chlorophenyl) 1H-pyrazole-3,5dicarboxylate) [Co (D4A1(3-Cl)1HP35D)] were synthesized by chemical root method and characterized by different method viz. X-ray diffraction, Fourier transform infrared spectroscopy and Transmission electron microscopy studies. All these studies were in good agreement with the synthesized complexes.

  8. Multi-sensor data fusion for measurement of complex freeform surfaces

    Science.gov (United States)

    Ren, M. J.; Liu, M. Y.; Cheung, C. F.; Yin, Y. H.

    2016-01-01

    Along with the rapid development of the science and technology in fields such as space optics, multi-scale enriched freeform surfaces are widely used to enhance the performance of the optical systems in both functionality and size reduction. Multi-sensor technology is considered as one of the promising methods to measure and characterize these surfaces at multiple scales. This paper presents a multi-sensor data fusion based measurement method to purposely extract the geometric information of the components with different scales which is used to establish a holistic geometry of the surface via data fusion. To address the key problems of multi-sensor data fusion, an intrinsic feature pattern based surface registration method is developed to transform the measured datasets to a common coordinate frame. Gaussian zero-order regression filter is then used to separate each measured data in different scales, and the datasets are fused based on an edge intensity data fusion algorithm within the same wavelength. The fused data at different scales is then merged to form a new surface with holistic multiscale information. Experimental study is presented to verify the effectiveness of the proposed method.

  9. Application of the Discrete Wavelet Transform to SEM and AFM Micrographs for Quantitative Analysis of Complex Surfaces.

    Science.gov (United States)

    Workman, Michael J; Serov, Alexey; Halevi, Barr; Atanassov, Plamen; Artyushkova, Kateryna

    2015-05-01

    The discrete wavelet transform (DWT) has found significant utility in process monitoring, filtering, and feature isolation of SEM, AFM, and optical images. Current use of the DWT for surface analysis assumes initial knowledge of the sizes of the features of interest in order to effectively isolate and analyze surface components. Current methods do not adequately address complex, heterogeneous surfaces in which features across multiple size ranges are of interest. Further, in situations where structure-to-property relationships are desired, the identification of features relevant for the function of the material is necessary. In this work, the DWT is examined as a tool for quantitative, length-scale specific surface metrology without prior knowledge of relevant features or length-scales. A new method is explored for determination of the best wavelet basis to minimize variation in roughness and skewness measurements with respect to change in position and orientation of surface features. It is observed that the size of the wavelet does not directly correlate with the size of features on the surface, and a method to measure the true length-scale specific roughness of the surface is presented. This method is applied to SEM and AFM images of non-precious metal catalysts, yielding new length-scale specific structure-to-property relationships for chemical speciation and fuel cell performance. The relationship between SEM and AFM length-scale specific roughness is also explored. Evidence is presented that roughness distributions of SEM images, as measured by the DWT, is representative of the true surface roughness distribution obtained from AFM.

  10. Structural complexity and land-surface energy exchange along a gradient from arctic tundra to boreal forest

    Science.gov (United States)

    Thompson, C.; Beringer, J.; Chapin, F. S.; McGuire, A.D.

    2004-01-01

    Question: Current climate changes in the Alaskan Arctic, which are characterized by increases in temperature and length of growing season, could alter vegetation structure, especially through increases in shrub cover or the movement of treeline. These changes in vegetation structure have consequences for the climate system. What is the relationship between structural complexity and partitioning of surface energy along a gradient from tundra through shrub tundra to closed canopy forest? Location: Arctic tundra-boreal forest transition in the Alaskan Arctic. Methods: Along this gradient of increasing canopy complexity, we measured key vegetation characteristics, including community composition, biomass, cover, height, leaf area index and stem area index. We relate these vegetation characteristics to albedo and the partitioning of net radiation into ground, latent, and sensible heating fluxes. Results: Canopy complexity increased along the sequence from tundra to forest due to the addition of new plant functional types. This led to non-linear changes in biomass, cover, and height in the understory. The increased canopy complexity resulted in reduced ground heat fluxes, relatively conserved latent heat fluxes and increased sensible heat fluxes. The localized warming associated with increased sensible heating over more complex canopies may amplify regional warming, causing further vegetation change in the Alaskan Arctic.

  11. Upscaling Radionuclide Retardation?Linking the Surface Complexation and Ion Exchange Mechanistic Approach to a Linear Kd Approach

    Energy Technology Data Exchange (ETDEWEB)

    Zavarin, M; Carle, S; Maxwell, R

    2004-05-14

    The LLNL near-field hydrologic source term (HST) model is based on a mechanistic approach to radionuclide retardation-that is, a thermodynamic description of chemical processes governing retardation in the near field, such as aqueous speciation, surface complexation, ion exchange, and precipitation The mechanistic approach allows for radionuclide retardation to vary both in space and time as a function of the complex reaction chemistry of the medium. This level of complexity is necessary for near-field HST transport modeling because of the non-linear reaction chemistry expected close to the radiologic source. Large-scale Corrective Action Unit (CAU) models-into which the near-field HST model results feed-require that the complexity of the mechanistic approach be reduced to a more manageable form (e.g. Linear, Langmuir, or Freundlich sorption isotherms, etc). The linear sorption isotherm (or K{sub d}) approach is likely the most simple approach for large-scale CAU models. It may also be the most appropriate since the reaction chemistry away from the near field is expected to be less complex and relatively steady state. However, if the radionuclide retardation approaches in near-field HST and large-scale CAU models are different, they must be proved consistent. In this report, we develop a method to link the near-field HST and large-scale CAU model radionuclide retardation approaches.

  12. Geophysical techniques applied to urban planning in complex near surface environments. Examples of Zaragoza, NE Spain

    Science.gov (United States)

    Pueyo-Anchuela, Ó.; Casas-Sainz, A. M.; Soriano, M. A.; Pocoví-Juan, A.

    Complex geological shallow subsurface environments represent an important handicap in urban and building projects. The geological features of the Central Ebro Basin, with sharp lateral changes in Quaternary deposits, alluvial karst phenomena and anthropic activity can preclude the characterization of future urban areas only from isolated geomechanical tests or from non-correctly dimensioned geophysical techniques. This complexity is here analyzed in two different test fields, (i) one of them linked to flat-bottomed valleys with irregular distribution of Quaternary deposits related to sharp lateral facies changes and irregular preconsolidated substratum position and (ii) a second one with similar complexities in the alluvial deposits and karst activity linked to solution of the underlying evaporite substratum. The results show that different geophysical techniques allow for similar geological models to be obtained in the first case (flat-bottomed valleys), whereas only the application of several geophysical techniques can permit to correctly evaluate the geological model complexities in the second case (alluvial karst). In this second case, the geological and superficial information permit to refine the sensitivity of the applied geophysical techniques to different indicators of karst activity. In both cases 3D models are needed to correctly distinguish alluvial lateral sedimentary changes from superimposed karstic activity.

  13. Immobilization of rhodium complexes at thiolate monolayers on gold surfaces : Catalytic and structural studies

    NARCIS (Netherlands)

    Belser, T; Stöhr, Meike; Pfaltz, A

    2005-01-01

    Chiral rhodium-diphosphine complexes have been incorporated into self-assembled thiolate monolayers (SAMS) on gold colloids. Catalysts of this type are of interest because they combine properties of homogeneous and heterogeneous systems. In addition, it should be possible to influence the catalytic

  14. Supported organometallic complexes: Surface chemistry, spectroscopy, and catalysis. Progress report, February 1, 1991--January 31, 1992

    Energy Technology Data Exchange (ETDEWEB)

    Marks, T.J.

    1992-02-01

    The long-range goal of this project is to elucidate and understand the surface chemistry and catalytic properties of well-defined, highly-reactive organometallic molecules (principally based upon abundant actinide, lanthanide, and early transition elements) adsorbed on metal oxides and halides. The nature of the adsorbed species is probed by a battery of chemical and physicochemical techniques, to understand the nature of the molecular-surface coordination chemistry and how this can give rise to extremely high catalytic activity. A complementary objective is to delineate the scope and mechanisms of the heterogeneous catalytic reactions, as well as to relate them both conceptually and functionally to model systems generated in solution.

  15. Laser Infrared Desorption Spectroscopy to Detect Complex Organic Molecules on Icy Planetary Surfaces

    Science.gov (United States)

    Sollit, Luke S.; Beegle, Luther W.

    2008-01-01

    Laser Desorption-Infrared Spectroscopy (LD-IR) uses an IR laser pulse to desorb surface materials while a spectrometer measures the emission spectrum of the desorbed materials (Figure 1). In this example, laser desorption operates by having the incident laser energy absorbed by near surface material (10 microns in depth). This desorption produces a plume that exists in an excited state at elevated temperatures. A natural analog for this phenomenon can be observed when comets approach the sun and become active and individual molecular emission spectra can be observed in the IR [1,2,3,4,5]. When this occurs in comets, the same species that initially emit radiation down to the ground state are free to absorb it, reducing the amount of detectable emission features. The nature of our technique results in absorption not occurring, because the laser pulse could easily be moved away form the initial desorption plume, and still have better spatial resolution then reflectance spectroscopy. In reflectance spectroscopy, trace components have a relatively weak signal when compared to the entire active nature of the surface. With LDIR, the emission spectrum is used to identify and analyze surface materials.

  16. Complex coacervation core micelles as anti-fouling agents on silica and polystyrene surfaces

    NARCIS (Netherlands)

    Burgh, van der S.; Fokkink, R.G.; Keizer, de A.; Cohen Stuart, M.A.

    2004-01-01

    The adsorption of mixtures of a diblock-co-polymer with a negatively charged block and a neutral, hydrophilic block and an oppositely charged homopolymer on anionic and hydrophobic surfaces was studied with reflectometry. It turned out that the adsorbed mass is at a maximum when the number of cation

  17. Laser Infrared Desorption Spectroscopy to Detect Complex Organic Molecules on Icy Planetary Surfaces

    Science.gov (United States)

    Sollit, Luke S.; Beegle, Luther W.

    2008-01-01

    Laser Desorption-Infrared Spectroscopy (LD-IR) uses an IR laser pulse to desorb surface materials while a spectrometer measures the emission spectrum of the desorbed materials (Figure 1). In this example, laser desorption operates by having the incident laser energy absorbed by near surface material (10 microns in depth). This desorption produces a plume that exists in an excited state at elevated temperatures. A natural analog for this phenomenon can be observed when comets approach the sun and become active and individual molecular emission spectra can be observed in the IR [1,2,3,4,5]. When this occurs in comets, the same species that initially emit radiation down to the ground state are free to absorb it, reducing the amount of detectable emission features. The nature of our technique results in absorption not occurring, because the laser pulse could easily be moved away form the initial desorption plume, and still have better spatial resolution then reflectance spectroscopy. In reflectance spectroscopy, trace components have a relatively weak signal when compared to the entire active nature of the surface. With LDIR, the emission spectrum is used to identify and analyze surface materials.

  18. Complexation behavior of gelatin with amphiphilic drug imipramine hydrochloride as studied by conductimetry, surface tensiometry and circular dichroism studies.

    Science.gov (United States)

    Ali, Mohd Sajid; Anjum, Kahkashan; Khan, Javed M; Khan, Rizwan H; Kabir-ud-Din

    2011-01-01

    Herein we report our studies carried out on the interaction between IMP and gelatin in aqueous medium at 25°C using conductimetry, surface tensiometry and circular dichroism (CD) techniques. Both surface tensiometry and conductimetry results indicate that the drug interacts with the gelatin in a surfactant-like manner, i.e., both critical aggregation (cac) and polymer saturation points (psp) were observed. The interaction starts with the formation of a highly surface-active complex as revealed by the lowering of surface tension on the addition of drug to the macromolecule. The decrease in cac on increasing gelatin concentration is an indication of the strong interaction between gelatin and IMP. However, at low concentration of gelatin the interaction was not much strong as exposed by surface tension study, i.e., the cac was not very clear (as with higher gelatin concentrations). As usual, the psp increased on increasing the gelatin concentration and was always higher than the critical micelle concentration of the drug in pure aqueous medium. Using CD measurements the influence of IMP on the secondary structure of gelatin in aqueous solutions was also investigated. CD studies (performed at very low drug concentrations) illustrated that the random coil content of gelatin increases with increasing drug concentration. Free energies of aggregation (ΔG(agg)) and micellization (ΔG(mic)) were computed with the help of degrees of micelle ionization obtained from the specific conductivity - [IMP] plots.

  19. Habitat Modeling in Complex Streams: Comparison of Terrestrial Laser Scanning and Traditional Surveying Techniques for Topographic Surface Generation

    Science.gov (United States)

    Hession, W. C.; Kozarek, J. L.; Resop, J. P.

    2009-12-01

    Accurate stream topography measurement is important for many environmental and ecological applications, such as hydraulic modeling and habitat characterization. Topological surveys are commonly created from point measurements using methods such as total station or global positioning system (GPS) surveying. However, surveying can be time intensive and limited by poor spatial resolution and difficulty in measuring complex morphology such as boulder-filled mountain streams. This can lead to measurement and interpolation errors, which can propagate to model uncertainty. Terrestrial laser scanning (TLS) has the potential to create high resolution, high accuracy topographic maps. Two methods, total station surveying and TLS, were used to measure the topography for an 80-meter forested reach on the Staunton River in Shenandoah National Park, Virginia, USA. The 2,500 surveyed points were directly compared to the TLS point cloud (approximately 9,500,000 points). The total station and TLS datasets were processed to create unique digital elevation models (DEM) of the stream reach. The resulting DEMs were used to evaluate uncertainties in topographic surfaces due to errors in traditional surveying techniques, to evaluate the propagation of uncertainty due to these errors in habitat modeling, and to evaluate the efficacy of utilizing TLS for complex, boulder streams. Comparison of resulting topography of a complex boulder stream using terrestrial laser scanning (grey-scale surfaces) and total station surveying (grid lines).

  20. Intranasal Administration of Novel Chitosan Nanoparticle/DNA Complexes Induces Antibody Response to Hepatitis B Surface Antigen in Mice.

    Science.gov (United States)

    Lebre, F; Borchard, G; Faneca, H; Pedroso de Lima, M C; Borges, O

    2016-02-01

    The generation of strong pathogen-specific immune responses at mucosal surfaces where hepatitis B virus (HBV) transmission can occur is still a major challenge. Therefore, new vaccines are urgently needed in order to overcome the limitations of existing parenteral ones. Recent studies show that this may be achieved by intranasal immunization. Chitosan has gained attention as a nonviral gene delivery system; however, its use in vivo is limited due to low transfection efficiency mostly related to strong interaction between the negatively charged DNA and the positively charged chitosan. We hypothesize that the adsorption of negatively charged human serum albumin (HSA) onto the surface of the chitosan particles would facilitate the intracellular release of DNA, enhancing transfection activity. Here, we demonstrate that a robust systemic immune response was induced after vaccination using HSA-loaded chitosan nanoparticle/DNA (HSA-CH NP/DNA) complexes. Furthermore, intranasal immunization with HSA-CH NP/DNA complexes induced HBV specific IgA in nasal and vaginal secretions; no systemic or mucosal responses were detected after immunization with DNA alone. Overall, our results show that chitosan-based DNA complexes elicited both humoral and mucosal immune response, making them an interesting and valuable gene delivery system for nasal vaccination against HBV.

  1. Metals complexation with humic acids in surface water of different natural–climatic zones

    OpenAIRE

    Dinu M. I.

    2013-01-01

    Humic acids extracted from different soils. The stability constants of metal humates and acid dissociation constant humic acids were calculated. Forms of metals in natural waters was determined with use account their chemical composition and content and properties of organic matter. We assessed metals speciation in water objects with account for competitive reactions resulting in formation of hydroxide, hydrocarbonate, sulfate, and chloride metal complexes and obtained a competitive series of...

  2. Metals complexation with humic acids in surface water of different natural–climatic zones

    Directory of Open Access Journals (Sweden)

    Dinu M. I.

    2013-04-01

    Full Text Available Humic acids extracted from different soils. The stability constants of metal humates and acid dissociation constant humic acids were calculated. Forms of metals in natural waters was determined with use account their chemical composition and content and properties of organic matter. We assessed metals speciation in water objects with account for competitive reactions resulting in formation of hydroxide, hydrocarbonate, sulfate, and chloride metal complexes and obtained a competitive series of metal activity in natural waters of the zones considered.

  3. SURFACE AREA AND MICRO-ROUGHNESS OF VOLCANIC ASH PARTICLES: A case study, Acigol Volcanic Complex, Cappadocia, Central Turkiye

    Science.gov (United States)

    Ersoy, O.; Aydar, E.; Sen, E.; Atici, G.

    2009-04-01

    Every single ash particle may convey information about its own formation environment and conditions. Certain features on particles may give a hint about the fragmentation regime, the intensity of fragmentation and quantity of water that partakes in the fragmentation process, etc. On this account, this study majored in the analysis on finer pyroclastic material, namely volcanic ash particles. Here, we used volcanic ash particles from Quaternary Acigol Volcanic complex (West of Nevsehir, Cappadocia, Central Turkiye). Quaternary Acigol Volcanic complex lies between the towns of Nevsehir and Acigol. It consists of a shallow caldera, a thick pyroclastic apron, seven obsidian dome clusters, and scattered cinder cones and associated lavas (Druitt et al., 1995). The products of explosive volcanism of the region were distinguished as two main Quaternary tuffs by a recent study (Druitt et al., 1995). Samples are from ashfall beds in a sequence of intercalated pumice fall, ashfall, and ignimbrite beds. In this study in order to achieve surface properties of volcanic ash particles, surface areas and micro-roughness of ash particles were measured on digital elevation models (DEM) reconstructed from stereoscopic images acquired on Scanning Electron Microscope (SEM) at varying specimen tilt angles. Correlation between surface texture of volcanic ash particles and eruption characteristics was determined.

  4. In vitro platelet activation, aggregation and platelet-granulocyte complex formation induced by surface modified single-walled carbon nanotubes.

    Science.gov (United States)

    Fent, János; Bihari, Péter; Vippola, Minnamari; Sarlin, Essi; Lakatos, Susan

    2015-08-01

    Surface modification of single-walled carbon nanotubes (SWCNTs) such as carboxylation, amidation, hydroxylation and pegylation is used to reduce the nanotube toxicity and render them more suitable for biomedical applications than their pristine counterparts. Toxicity can be manifested in platelet activation as it has been shown for SWCNTs. However, the effect of various surface modifications on the platelet activating potential of SWCNTs has not been tested yet. In vitro platelet activation (CD62P) as well as the platelet-granulocyte complex formation (CD15/CD41 double positivity) in human whole blood were measured by flow cytometry in the presence of 0.1mg/ml of pristine or various surface modified SWCNTs. The effect of various SWCNTs was tested by whole blood impedance aggregometry, too. All tested SWCNTs but the hydroxylated ones activate platelets and promote platelet-granulocyte complex formation in vitro. Carboxylated, pegylated and pristine SWCNTs induce whole blood aggregation as well. Although pegylation is preferred from biomedical point of view, among the samples tested by us pegylated SWCNTs induced far the most prominent activation and a well detectable aggregation of platelets in whole blood.

  5. The influence of surface properties on uptake of oil into complex coacervate microcapsules.

    Science.gov (United States)

    Rabiskova, M; Song, J; Opawale, F O; Burgess, D J

    1994-08-01

    A range of surfactants with different hydrophile-lipophile balance (HLB) values was selected to investigate the influence of interfacial properties on the uptake of oil droplets into complex coacervate microcapsules. The well characterized gelatin/acacia complex coacervate system was used in this study and the encapsulation of squalane, and oleic acid was investigated. The surfactants investigated were Span 85, Span 80, Span 40, egg yolk lecithin, and Tween 80. Combinations of surfactants were utilized to obtain intermediate HLB values. The percentage oil encapsulated was determined gravimetrically, based on the initial concentration and the amount extracted from the microcapsules. The aqueous interfacial tension values of the oils and oil/surfactant systems were measured using the Wilhelmy plate method. The interfacial properties were correlated to the percentage oil uptake by the coacervate phase. The relative hydrophobicity/lipophilicity of the oil influenced its uptake by complex coacervate droplets. The presence of surfactant affected oil uptake, depending on the HLB value of the surfactant or surfactant mixture. Uptake of squalane by the gelatin/acacia coacervates was found to be optimized by the addition of surfactants with HLB values in the range 2.5-6. The percentage uptake of oil decreased rapidly for systems prepared containing surfactants with HLB values outside this range. No correlation was observed between oil uptake by the coacervate phase and the interfacial tension of the oil and oil/surfactant systems with double-distilled deionized water.

  6. Representing spatial and temporal complexity in ecohydrological models: a meta-analysis focusing on groundwater - surface water interactions

    Science.gov (United States)

    McDonald, Karlie; Mika, Sarah; Kolbe, Tamara; Abbott, Ben; Ciocca, Francesco; Marruedo, Amaia; Hannah, David; Schmidt, Christian; Fleckenstein, Jan; Karuse, Stefan

    2016-04-01

    Sub-surface hydrologic processes are highly dynamic, varying spatially and temporally with strong links to the geomorphology and hydrogeologic properties of an area. This spatial and temporal complexity is a critical regulator of biogeochemical and ecological processes within the interface groundwater - surface water (GW-SW) ecohydrological interface and adjacent ecosystems. Many GW-SW models have attempted to capture this spatial and temporal complexity with varying degrees of success. The incorporation of spatial and temporal complexity within GW-SW model configuration is important to investigate interactions with transient storage and subsurface geology, infiltration and recharge, and mass balance of exchange fluxes at the GW-SW ecohydrological interface. Additionally, characterising spatial and temporal complexity in GW-SW models is essential to derive predictions using realistic environmental conditions. In this paper we conduct a systematic Web of Science meta-analysis of conceptual, hydrodynamic, and reactive and heat transport models of the GW-SW ecohydrological interface since 2004 to explore how these models handled spatial and temporal complexity. The freshwater - groundwater ecohydrological interface was the most commonly represented in publications between 2004 and 2014 with 91% of papers followed by marine 6% and estuarine systems with 3% of papers. Of the GW-SW models published since 2004, the 52% have focused on hydrodynamic processes and heat and reactive transport). Within the hydrodynamic subset, 25% of models focused on a vertical depth of limitations of incorporating spatial and temporal variability into GW-SW models are identified as the inclusion of woody debris, carbon sources, subsurface geological structures and bioclogging into model parameterization. The technological limitations influence the types of models applied, such as hydrostatic coupled models and fully intrinsic saturated and unsaturated models, and the assumptions or

  7. Transitions between smooth and complex stick-slip sliding of surfaces

    Science.gov (United States)

    Gourdon, Delphine; Israelachvili, Jacob N.

    2003-08-01

    Shear measurements were performed on mica surfaces with molecularly thin films of squalane (C30H62) confined between them. Squalane is a branched hydrocarbon liquid that can be in the liquid, glassy, or liquid-crystalline state under confinement. The friction forces, especially the transitions between smooth and intermittent (e.g., stick-slip) sliding, were measured over a wider range of applied loads (pressures), sliding velocities (shear rates), and temperatures than in previous studies. The results reveal that, depending on the conditions, qualitatively different behavior can arise in the same system. These include both abrupt and continuous transitions, both upper and lower critical transition temperatures, short and very long transient effects, and chaotic, sawtooth, or sinusoidal stick-slip that can slowly decay with time or distance sheared. The differences between these branched and simpler, e.g., spherical, unbranched molecules are compared, as well as with unlubricated (dry) surfaces and macroscopic (geological) systems.

  8. New Approach to Investigating Near-Surface Structures for Complex Seismic Topography

    Institute of Scientific and Technical Information of China (English)

    JiangWenbo; HeZhanxiang; LiuHong

    2003-01-01

    Addressed in this article is a new approach to investigating the near-surface structures through the use of the electromagnetic sounding. The advantages of the electro-magnetic sounding method and the problems of the nearssurface investigation and their solutions are described. Actual examples from the southwestern Takelamagan, western Qaidam and northern Xinjiang are taken to demonstrate the results and the capability of this approach in solving the nearsurface problems. It is also pointed out that the new approach could become both the basis for designing seismic acquisition parameters and determining the seismic shot locations,as well as supplying near-surface velocity models for seismic data processing so as to improve the quality of seismic sections.

  9. A multi-perspective dynamic feature concept in adaptive NC machining of complex freeform surfaces

    OpenAIRE

    Liu, Xu; Li, Yingguang; Gao, James

    2016-01-01

    This paper presents a new concept of feature for freeform surface machining that defines the changes in feature status during real manufacturing situations which have not been sufficiently addressed by current international standards and previous research in feature technology. These changes are multi-perspective, including (i) changes in depth-of-cut: the geometry of a feature in the depth-of-cut direction changes during different machining operations such as roughing, semi-finishing and fin...

  10. Self-organization of multifunctional surfaces--the fingerprints of light on a complex system.

    Science.gov (United States)

    Reinhardt, Hendrik; Kim, Hee-Cheol; Pietzonka, Clemens; Kruempelmann, Julia; Harbrecht, Bernd; Roling, Bernhard; Hampp, Norbert

    2013-06-25

    Nanocomposite patterns and nanotemplates are generated by a single-step bottom-up concept that introduces laser-induced periodic surface structures (LIPSS) as a tool for site-specific reaction control in multicomponent systems. Periodic intensity fluctuations of this photothermal stimulus inflict spatial-selective reorganizations, dewetting scenarios and phase segregations, thus creating regular patterns of anisotropic physicochemical properties that feature attractive optical, electrical, magnetic, and catalytic properties.

  11. Unique secreted–surface protein complex of Lactobacillus rhamnosus, identified by phage display

    Science.gov (United States)

    Gagic, Dragana; Wen, Wesley; Collett, Michael A; Rakonjac, Jasna

    2013-01-01

    Proteins are the most diverse structures on bacterial surfaces; hence, they are candidates for species- and strain-specific interactions of bacteria with the host, environment, and other microorganisms. Genomics has decoded thousands of bacterial surface and secreted proteins, yet the function of most cannot be predicted because of the enormous variability and a lack of experimental data that would allow deduction of function through homology. Here, we used phage display to identify a pair of interacting extracellular proteins in the probiotic bacterium Lactobacillus rhamnosus HN001. A secreted protein, SpcA, containing two bacterial immunoglobulin-like domains type 3 (Big-3) and a domain distantly related to plant pathogen response domain 1 (PR-1-like) was identified by screening of an L. rhamnosus HN001 library using HN001 cells as bait. The SpcA-“docking” protein, SpcB, was in turn detected by another phage display library screening, using purified SpcA as bait. SpcB is a 3275-residue cell-surface protein that contains general features of large glycosylated Serine-rich adhesins/fibrils from gram-positive bacteria, including the hallmark signal sequence motif KxYKxGKxW. Both proteins are encoded by genes within a L. rhamnosus-unique gene cluster that distinguishes this species from other lactobacilli. To our knowledge, this is the first example of a secreted-docking protein pair identified in lactobacilli. PMID:23233310

  12. Application of response surface methodology for exploring β-cyclodextrin effects on the decoloration of spiropyran complexes

    Science.gov (United States)

    Wang, Li-Fen

    2016-10-01

    Response surface method is applied here to trace the photochromic path and explore the substituent and β-cyclodextrin effects on the decoloration of the spiropyran/β-cyclodextrin polymer (SP/CDP) complex. Calculations support the ultraviolet/visible experimental results, suggesting that introducing an electron-withdrawing group to the benzopyryl moiety of SPs favors an enhancement in their decoloration, whereas replacing the benzopyryl with a naphthopyryl moiety obstructs their decoloration. CDP complexation weakens the C1sbnd O bond of the closed SP form and enhances the polar zwitterionic structure in the open photomerocynine form. However, the electron-withdrawing group strengthens the interaction of benzopyryl SPs with CDP, thereby hindering their decoloration.

  13. Comparison of zinc complexation properties of dissolved organic matter from surface waters and wastewater treatment plant effluents

    Institute of Scientific and Technical Information of China (English)

    CHENG Tao

    2005-01-01

    Unlike natural organic matter(NOM), wastewater organic matter(WWOM) from wastewater treatment plant effluents has not been extensively studied with respect to complexation reactions with heavy metals such as copper or zinc. In this study, organic matter from surface waters and a wastewater treatment plant effluent were concentrated by reverse osmosis(RO) method. The samples were treated in the laboratory to remove trace metals and major cations. The zinc complexing properties of both NOM and the WWOM were studied by square wave anodic stripping voltammetry(SWASV). Experimental data were compared to predictions using the Windermere Humic Aqueous Model(WHAM) Version VI. We found that the zinc binding of WWOM was much stronger than that of NOM and not well predicted by WHAM. This suggests that in natural water bodies that receive wastewater treatment plant effluents the ratio of WWOM to NOM must be taken into account in order to accurately predict free zinc activities.

  14. Understanding Complex Spectral Signatures of Embedded Excess Protons in Molecular Scaffolds with Third Order Corrections to the Harmonic Potential Surface

    Science.gov (United States)

    Deblase, Andrew F.; Johnson, Mark A.; Lectka, Thomas; Wang, Xun; Jordan, Kenneth D.; McCoy, Anne B.

    2013-06-01

    Overtones and combination bands observed in vibrational predissociation spectra of cold ions can often be anticipated by expanding the potential energy surface to third order. This is achieved by relating the third derivatives to the matrix elements that couple the allowed and forbidden states in the harmonic basis. Such a strategy has been successful in predicting Fermi resonances in formic acid clusters and some charged H-bonded complexes. Furthermore, third order couplings have been used to develop a vibrational adiabatic model in which excitation of a bright state is distributed over a Franck-Condon envelop of a lower energy mode, such as a water rocking against triatomic domains of molecular anions. Previous applications include the analysis of long vibrational progressions of soft modes in the OH stretching region of the actetate-water binary complex. Here we explore to extent to which this order of correction captures the irregular patterns associated with intramolecular proton bonds.

  15. A coupled remote sensing and the Surface Energy Balance with Topography Algorithm (SEBTA to estimate actual evapotranspiration under complex terrain

    Directory of Open Access Journals (Sweden)

    Z. Q. Gao

    2010-07-01

    Full Text Available Evapotranspiration (ET may be used as an ecological indicator to address the ecosystem complexity. The accurate measurement of ET is of great significance for studying environmental sustainability, global climate changes, and biodiversity. Remote sensing technologies are capable of monitoring both energy and water fluxes on the surface of the Earth. With this advancement, existing models, such as SEBAL, S_SEBI and SEBS, enable us to estimate the regional ET with limited temporal and spatial scales. This paper extends the existing modeling efforts with the inclusion of new components for ET estimation at varying temporal and spatial scales under complex terrain. Following a coupled remote sensing and surface energy balance approach, this study emphasizes the structure and function of the Surface Energy Balance with Topography Algorithm (SEBTA. With the aid of the elevation and landscape information, such as slope and aspect parameters derived from the digital elevation model (DEM, and the vegetation cover derived from satellite images, the SEBTA can fully account for the dynamic impacts of complex terrain and changing land cover in concert with some varying kinetic parameters (i.e., roughness and zero-plane displacement over time. Besides, the dry and wet pixels can be recognized automatically and dynamically in image processing thereby making the SEBTA more sensitive to derive the sensible heat flux for ET estimation. To prove the application potential, the SEBTA was carried out to present the robust estimates of 24 h solar radiation over time, which leads to the smooth simulation of the ET over seasons in northern China where the regional climate and vegetation cover in different seasons compound the ET calculations. The SEBTA was validated by the measured data at the ground level. During validation, it shows that the consistency index reached 0.92 and the correlation coefficient was 0.87.

  16. Surface complexation modeling of U(VI) sorption on GMZ bentonite in the presence of fulvic acid

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Jie [Lanzhou Univ. (China). Radiochemistry Laboratory; Ministry of Industry and Information Technology, Guangzhou (China). The 5th Electronics Research Inst.; Luo, Daojun [Ministry of Industry and Information Technology, Guangzhou (China). The 5th Electronics Research Inst.; Qiao, Yahua; Wang, Liang; Zhang, Chunming [Ministry of Environmental Protection, Beijing (China). Nuclear and Radiation Safety Center; Wu, Wangsuo [Lanzhou Univ. (China). Radiochemistry Laboratory; Ye, Yuanlv [Ministry of Environmental Protection, Beijing (China). Nuclear and Radiation Safety Center; Lanzhou Univ. (China). Radiochemistry Laboratory

    2017-03-01

    In this work, experiments and modeling for the interactions between uranyl ion and GMZ bentonite in the presence of fulvic acid are presented. The results demonstrated that FA is strongly bound to GMZ bentonite, and these molecules have a very large effect on the U(VI) sorption. The results also demonstrated that U(VI) sorption to GMZ bentonite in the presence and absence of sorbed FA can be well predicted by combining SHM and DLM. According to the model calculations, the nature of the interactions between FA with U(VI) at GMZ bentonite surface is mainly surface complex. The first attempt to simulate clay interaction with humus by the SHM model.

  17. High-resolution MR imaging of triangular fibrocartilage complex (TFCC): comparison of microscopy coils and a conventional small surface coil

    Energy Technology Data Exchange (ETDEWEB)

    Yoshioka, Hiroshi [Department of Radiology, University of Tsukuba, Tsukuba (Japan); Department of Radiology, Brigham and Women' s Hospital, 75 Francis Street, 02115, Boston, MA (United States); Ueno, Teruko; Itai, Yuji [Department of Radiology, University of Tsukuba, Tsukuba (Japan); Tanaka, Toshikazu [Department of Orthopedic Surgery, Tsukuba Kinen Hospital, Tsukuba (Japan); Shindo, Masashi [Tsukuba University Hospital, Tsukuba (Japan)

    2003-10-01

    To compare MR images of the triangular fibrocartilage complex (TFCC) using microscopy coils with those using a conventional surface coil qualitatively and quantitatively. Proton density-weighted images and T2*-weighted images of the TFCC from ten normal volunteers were obtained with a conventional surface coil (C4 coil; 80 mm in diameter), a 47-mm microscopy surface coil and a 23-mm microscopy surface coil at 1.5 T. Qualitative image analysis of MR images with three coils was performed by two radiologists who assigned one of five numerical scores (0, nonvisualization; 1, poor; 2, average; 3, good; 4, excellent) for five TFCC components, which were disc proper, triangular ligament, meniscus homologue, ulnotriquetral and ulnolunate ligament. Quantitative analysis included the signal-to-noise ratio (S/N) of the disc proper of TFCC, the lunate cartilage, the lunate bone and the contrast-noise-ratio (C/N) between articular cartilage and disc proper or bone marrow were measured. All structures show higher scores qualitatively on MR with microscopy coils than those with a C4 coil, and the difference was significant with the exception of the ulnolunate ligament. MR with microscopy coils showed significantly higher S/N values than those with a conventional surface coil (P<0.05 to P<0.001). T2*-weighted images using microscopy coils showed significantly higher cartilage-disc proper C/N and cartilage-bone marrow C/N (P<0.01 to P<0.001). On proton density-weighted images, the C/N between cartilage and disc proper with two microscopy coils was significantly higher (P<0.01) than that with a conventional coil. High-resolution MR images of the normal wrist using microscopy coils were superior to those using a conventional surface coil qualitatively and quantitatively. High-resolution MR imaging with a microscopy coil would be a promising method to diagnose TFCC lesions. (orig.)

  18. A stable finite difference method for the elastic wave equation on complex geometries with free surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Appelo, D; Petersson, N A

    2007-12-17

    The isotropic elastic wave equation governs the propagation of seismic waves caused by earthquakes and other seismic events. It also governs the propagation of waves in solid material structures and devices, such as gas pipes, wave guides, railroad rails and disc brakes. In the vast majority of wave propagation problems arising in seismology and solid mechanics there are free surfaces. These free surfaces have, in general, complicated shapes and are rarely flat. Another feature, characterizing problems arising in these areas, is the strong heterogeneity of the media, in which the problems are posed. For example, on the characteristic length scales of seismological problems, the geological structures of the earth can be considered piecewise constant, leading to models where the values of the elastic properties are also piecewise constant. Large spatial contrasts are also found in solid mechanics devices composed of different materials welded together. The presence of curved free surfaces, together with the typical strong material heterogeneity, makes the design of stable, efficient and accurate numerical methods for the elastic wave equation challenging. Today, many different classes of numerical methods are used for the simulation of elastic waves. Early on, most of the methods were based on finite difference approximations of space and time derivatives of the equations in second order differential form (displacement formulation), see for example [1, 2]. The main problem with these early discretizations were their inability to approximate free surface boundary conditions in a stable and fully explicit manner, see e.g. [10, 11, 18, 20]. The instabilities of these early methods were especially bad for problems with materials with high ratios between the P-wave (C{sub p}) and S-wave (C{sub s}) velocities. For rectangular domains, a stable and explicit discretization of the free surface boundary conditions is presented in the paper [17] by Nilsson et al. In summary

  19. Surface hydrophobization by electrostatic deposition of hydrophobically modified poly(acrylates) and their complexes with surfactants

    Science.gov (United States)

    Gîfu, Ioana Cătălina; Maxim, Monica Elisabeta; Iovescu, Alina; Simion, Elena Livia; Aricov, Ludmila; Anastasescu, Mihai; Munteanu, Cornel; Anghel, Dan-Florin

    2016-05-01

    The present study demonstrates the hydrophobic effect of poly(electrolyte) multilayer films when they are alkyl-grafted and complexed or not with surfactants. For this purpose, sodium hydrophobically modified poly(acrylates) (PACnNa, n = 10, 18) or their anionic complexes with alkyltrimethylammonium bromides (CxTAB, x = 10, 12, 14, 18), and the cationic poly(diallyldimethyldiammonium chloride) (PDDAMAC) are assembled by layer-by-layer deposition on a glass substrate. Contact angle (CA) measurements reveal that films constructed with PACnNa-CxTAB/PDADMAC are superior water repellants than those of PACnNa/PDADMAC. For example, the highest CA is obtained for the PAC18Na-C18TAB/PDADMAC. Moreover, it has been observed that the CA increases with the alkyl chain length of PACnNa and of surfactant. The film roughness and thickness have the same trend as wettability. Thinner and less coarse films are obtained by NaCl addition, as witnessed by SEM and AFM.

  20. Uranium(VI) adsorption and surface complexation modeling onto background sediments from the F-Area Savannah River Site.

    Science.gov (United States)

    Dong, Wenming; Tokunaga, Tetsu K; Davis, James A; Wan, Jiamin

    2012-02-07

    The mobility of an acidic uranium waste plume in the F-Area of Savannah River Site is of great concern. In order to understand and predict uranium mobility, U(VI) adsorption experiments were performed as a function of pH using background F-Area aquifer sediments and reference goethite and kaolinite (major reactive phases of F-Area sediments), and a component-additivity (CA) based surface complexation model (SCM) was developed. Our experimental results indicate that the fine fractions (≤45 μm) in sediments control U(VI) adsorption due to their large surface area, although the quartz sands show a stronger adsorption ability per unit surface area than the fine fractions at pH 4.0. Our CA model combines an existing U(VI) SCM for goethite and a modified U(VI) SCM for kaolinite along with estimated relative surface area abundances of these component minerals. The modeling approach successfully predicts U(VI) adsorption behavior by the background F-Area sediments. The model suggests that exchange sites on kaolinite dominate U(VI) adsorption at pH 6.0.

  1. A method for obtaining distributed surface flux measurements in complex terrain

    Science.gov (United States)

    Daniels, M. H.; Pardyjak, E.; Nadeau, D. F.; Barrenetxea, G.; Brutsaert, W. H.; Parlange, M. B.

    2011-12-01

    Sonic anemometers and gas analyzers can be used to measure fluxes of momentum, heat, and moisture over flat terrain, and with the proper corrections, over sloping terrain as well. While this method of obtaining fluxes is currently the most accurate available, the instruments themselves are costly, making installation of many stations impossible for most campaign budgets. Small, commercial automatic weather stations (Sensorscope) are available at a fraction of the cost of sonic anemometers or gas analyzers. Sensorscope stations use slow-response instruments to measure standard meteorological variables, including wind speed and direction, air temperature, humidity, surface skin temperature, and incoming solar radiation. The method presented here makes use of one sonic anemometer and one gas analyzer along with a dozen Sensorscope stations installed throughout the Val Ferret catchment in southern Switzerland in the summers of 2009, 2010 and 2011. Daytime fluxes are calculated using Monin-Obukhov similarity theory in conjunction with the surface energy balance at each Sensorscope station as well as at the location of the sonic anemometer and gas analyzer, where a suite of additional slow-response instruments were co-located. Corrections related to slope angle were made for wind speeds and incoming shortwave radiation measured by the horizontally-mounted cup anemometers and incoming solar radiation sensors respectively. A temperature correction was also applied to account for daytime heating inside the radiation shield on the slow-response temperature/humidity sensors. With these corrections, we find a correlation coefficient of 0.77 between u* derived using Monin-Obukhov similarity theory and that of the sonic anemometer. Calculated versus measured heat fluxes also compare well and local patterns of latent heat flux and measured surface soil moisture are correlated.

  2. Comparison of classical surfacing and rapid surfacing for complex surface reconstruction%传统方法与快速曲面方法进行复杂曲面重建的比较*

    Institute of Scientific and Technical Information of China (English)

    王秉操; 王殊轶; 毕东东; 郑加宽; 刘斌

    2013-01-01

    BACKGROUND:Reverse engineering technology has been widely used in surgery, and how to produce the model that meet the rapid prototyping processing rapidly and effectively has attracted more and more attention. OBJECTIVE:To compare the classical surfacing and rapid surfacing for complex surface reconstruction based on the summary of the commonly used surface reconstruction modeling technique. METHODS:VIVID9i non-contact three-dimensional digital scanner produced by Konica, Japan was used to perform the three-dimensional coordinate measuring on faces of 30 col ege students. The classical surfacing and rapid surfacing approaches were used to surfacing reconstruct the facial point cloud data, and to perform error analysis and smoothness evaluation. RESULTS AND CONCLUSION:The results show that the maximum distance of surfaces and point clouds reconstructed with the classical surfacing and rapid surfacing approaches were 2.99 mm and 0.69 mm. The surface made by classical surfacing approach was smoother than that made by rapid surfacing approach. There is a conclusion that rapid surfacing approach is more efficient method for complex surface reconstruction, and provides a reference for the three-dimensional reconstruction of complex surfaces.%  背景:逆向工程技术在外科手术中的应用越来越广泛,如何快速、高效地制作出满足快速原型加工所需的模型越来越受到医务人员的关注。  目的:在对常用曲面重构方法建模技术进行总结的基础上,针对传统方法和快速曲面方法对面部复杂曲面进行了重建比较分析。  方法:采用日本Konica公司生产的VIVID9i非接触式三维数字化仪对30名在校大学生面部进行三维坐标测量。采用传统方法和快速曲面方法对扫描得到的面部点云数据进行曲面重建,并对结果进行误差分析和光顺性评价。  结果与结论:传统方法和快速曲面方法重建曲面与原

  3. Evolution of Complex Target SELEX to Identify Aptamers against Mammalian Cell-Surface Antigens

    Directory of Open Access Journals (Sweden)

    Prabodhika Mallikaratchy

    2017-01-01

    Full Text Available The demand has increased for sophisticated molecular tools with improved detection limits. Such molecules should be simple in structure, yet stable enough for clinical applications. Nucleic acid aptamers (NAAs represent a class of molecules able to meet this demand. In particular, aptamers, a class of small nucleic acid ligands that are composed of single-stranded modified/unmodified RNA/DNA molecules, can be evolved from a complex library using Systematic Evolution of Ligands by EXponential enrichment (SELEX against almost any molecule. Since its introduction in 1990, in stages, SELEX technology has itself undergone several modifications, improving selection and broadening the repertoire of targets. This review summarizes these milestones that have pushed the field forward, allowing researchers to generate aptamers that can potentially be applied as therapeutic and diagnostic agents.

  4. Evolution of Complex Target SELEX to Identify Aptamers against Mammalian Cell-Surface Antigens.

    Science.gov (United States)

    Mallikaratchy, Prabodhika

    2017-01-30

    The demand has increased for sophisticated molecular tools with improved detection limits. Such molecules should be simple in structure, yet stable enough for clinical applications. Nucleic acid aptamers (NAAs) represent a class of molecules able to meet this demand. In particular, aptamers, a class of small nucleic acid ligands that are composed of single-stranded modified/unmodified RNA/DNA molecules, can be evolved from a complex library using Systematic Evolution of Ligands by EXponential enrichment (SELEX) against almost any molecule. Since its introduction in 1990, in stages, SELEX technology has itself undergone several modifications, improving selection and broadening the repertoire of targets. This review summarizes these milestones that have pushed the field forward, allowing researchers to generate aptamers that can potentially be applied as therapeutic and diagnostic agents.

  5. Large Eddy Simulation of complex sidearms subject to solar radiation and surface cooling.

    Science.gov (United States)

    Dittko, Karl A; Kirkpatrick, Michael P; Armfield, Steven W

    2013-09-15

    Large Eddy Simulation (LES) is used to model two lake sidearms subject to heating from solar radiation and cooling from a surface flux. The sidearms are part of Lake Audrey, NJ, USA and Lake Alexandrina, SA, Australia. The simulation domains are created using bathymetry data and the boundary is modelled with an Immersed Boundary Method. We investigate the cooling and heating phases with separate quasi-steady state simulations. Differential heating occurs in the cavity due to the changing depth. The resulting temperature gradients drive lateral flows. These flows are the dominant transport process in the absence of wind. Study in this area is important in water quality management as the lateral circulation can carry particles and various pollutants, transporting them to and mixing them with the main lake body.

  6. On-Surface Observation of the Formation of Organometallic Complex in a Supramolecular Network

    Science.gov (United States)

    Li, Yibao; Cheng, Linxiu; Liu, Chunhua; Liu, Wei; Fan, Yulan; Fan, Xiaolin; Zeng, Qingdao

    2015-06-01

    The on-surface formation of organometallic monomers or oligomers, especially in supramolecular network, attracts an extensive interest for chemists and material scientist. In this work, we have investigated metal coordination between zinc (II) phthalocyanine (ZnPc) and 1, 3-di (4-pyridyl) propane (dipy-pra) in the 2, 6, 11-tricarboxydecyloxy-3, 7, 10-triundecyloxy triphenylene (asym-TTT) supramolecular template by means of scanning tunneling microscopy (STM) on highly oriented pyrolytic graphite (HOPG) substrate under ambient conditions. The experimental results demonstrate that every two ZnPc molecules in one nano-reactor connect with each other through one dipy-pra molecule by metal-coordination interaction. In this coordinating process, the template of asym-TTT supramolecular networks plays a significant role.

  7. Simple models for complex natural surfaces - A strategy for the hyperspectral era of remote sensing

    Science.gov (United States)

    Adams, John B.; Smith, Milton O.; Gillespie, Alan R.

    1989-01-01

    A two-step strategy for analyzing multispectral images is described. In the first step, the analyst decomposes the signal from each pixel (as expressed by the radiance or reflectance values in each channel) into components that are contributed by spectrally distinct materials on the ground, and those that are due to atmospheric effects, instrumental effects, and other factors, such as illumination. In the second step, the isolated signals from the materials on the ground are selectively edited, and recombined to form various unit maps that are interpretable within the framework of field units. The approach has been tested on multispectral images of a variety of natural land surfaces ranging from hyperarid deserts to tropical rain forests. Data were analyzed from Landsat MSS (multispectral scanner) and TM (Thematic Mapper), the airborne NS001 TM simulator, Viking Lander and Orbiter, AIS, and AVRIS (Airborne Visible and Infrared Imaging Spectrometer).

  8. Chirality of weakly bound complexes: The potential energy surfaces for the hydrogen-peroxide−noble-gas interactions

    Energy Technology Data Exchange (ETDEWEB)

    Roncaratti, L. F., E-mail: lz@fis.unb.br; Leal, L. A.; Silva, G. M. de [Instituto de Física, Universidade de Brasília, 70910 Brasília (Brazil); Pirani, F. [Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, 06123 Perugia (Italy); Aquilanti, V. [Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, 06123 Perugia (Italy); Instituto de Física, Universidade Federal da Bahia, 40210 Salvador (Brazil); Gargano, R. [Instituto de Física, Universidade de Brasília, 70910 Brasília (Brazil); Departments of Chemistry and Physics, University of Florida, Quantum Theory Project, Gainesville, Florida 32611 (United States)

    2014-10-07

    We consider the analytical representation of the potential energy surfaces of relevance for the intermolecular dynamics of weakly bound complexes of chiral molecules. In this paper we study the H{sub 2}O{sub 2}−Ng (Ng=He, Ne, Ar, Kr, and Xe) systems providing the radial and the angular dependence of the potential energy surface on the relative position of the Ng atom. We accomplish this by introducing an analytical representation which is able to fit the ab initio energies of these complexes in a wide range of geometries. Our analysis sheds light on the role that the enantiomeric forms and the symmetry of the H{sub 2}O{sub 2} molecule play on the resulting barriers and equilibrium geometries. The proposed theoretical framework is useful to study the dynamics of the H{sub 2}O{sub 2} molecule, or other systems involving O–O and S–S bonds, interacting by non-covalent forces with atoms or molecules and to understand how the relative orientation of the O–H bonds changes along collisional events that may lead to a hydrogen bond formation or even to selectivity in chemical reactions.

  9. Context dependence in complex adaptive landscapes: frequency and trait-dependent selection surfaces within an adaptive radiation of Caribbean pupfishes.

    Science.gov (United States)

    Martin, Christopher H

    2016-06-01

    The adaptive landscape provides the foundational bridge between micro- and macroevolution. One well-known caveat to this perspective is that fitness surfaces depend on ecological context, including competitor frequency, traits measured, and resource abundance. However, this view is based largely on intraspecific studies. It is still unknown how context-dependence affects the larger features of peaks and valleys on the landscape which ultimately drive speciation and adaptive radiation. Here, I explore this question using one of the most complex fitness landscapes measured in the wild in a sympatric pupfish radiation endemic to San Salvador Island, Bahamas by tracking survival and growth of laboratory-reared F2 hybrids. I present new analyses of the effects of competitor frequency, dietary isotopes, and trait subsets on this fitness landscape. Contrary to expectations, decreasing competitor frequency increased survival only among very common phenotypes, whereas less common phenotypes rarely survived despite few competitors, suggesting that performance, not competitor frequency, shapes large-scale features of the fitness landscape. Dietary isotopes were weakly correlated with phenotype and growth, but did not explain additional survival variation. Nonlinear fitness surfaces varied substantially among trait subsets, revealing one-, two-, and three-peak landscapes, demonstrating the complexity of selection in the wild, even among similar functional traits. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

  10. Mussel Coating Protein-Derived Complex Coacervates Mitigate Frictional Surface Damage

    Science.gov (United States)

    2015-01-01

    The role of friction in the functional performance of biomaterial interfaces is widely reckoned to be critical and complicated but poorly understood. To better understand friction forces, we investigated the natural adaptation of the holdfast or byssus of mussels that live in high-energy surf habitats. As the outermost covering of the byssus, the cuticle deserves particular attention for its adaptations to frictional wear under shear. In this study, we coacervated one of three variants of a key cuticular component, mussel foot protein 1, mfp-1 [(1) Mytilus californianus mcfp-1, (2) rmfp-1, and (3) rmfp-1-Dopa], with hyaluronic acid (HA) and investigated the wear protection capabilities of these coacervates to surfaces (mica) during shear. Native mcfp-1/HA coacervates had an intermediate coefficient of friction (μ ∼0.3) but conferred excellent wear protection to mica with no damage from applied loads, F⊥, as high as 300 mN (pressure, P, > 2 MPa). Recombinant rmfp-1/HA coacervates exhibited a comparable coefficient of friction (μ ∼0.3); however, wear protection was significantly inferior (damage at F⊥ > 60 mN) compared with that of native protein coacervates. Wear protection of rmfp-1/HA coacervates increased 5-fold upon addition of the surface adhesive group 3,4-dihydroxyphenylalanine, (Dopa). We propose a Dopa-dependent wear protection mechanism to explain the differences in wear protection between coacervates. Our results reveal a significant untapped potential for coacervates in applications that require adhesion, lubrication, and wear protection. These applications include artificial joints, contact lenses, dental sealants, and hair and skin conditioners. PMID:26618194

  11. Mussel Coating Protein-Derived Complex Coacervates Mitigate Frictional Surface Damage.

    Science.gov (United States)

    Miller, Dusty Rose; Das, Saurabh; Huang, Kuo-Ying; Han, Songi; Israelachvili, Jacob N; Waite, J Herbert

    2015-11-09

    The role of friction in the functional performance of biomaterial interfaces is widely reckoned to be critical and complicated but poorly understood. To better understand friction forces, we investigated the natural adaptation of the holdfast or byssus of mussels that live in high-energy surf habitats. As the outermost covering of the byssus, the cuticle deserves particular attention for its adaptations to frictional wear under shear. In this study, we coacervated one of three variants of a key cuticular component, mussel foot protein 1, mfp-1 [(1) Mytilus californianus mcfp-1, (2) rmfp-1, and (3) rmfp-1-Dopa], with hyaluronic acid (HA) and investigated the wear protection capabilities of these coacervates to surfaces (mica) during shear. Native mcfp-1/HA coacervates had an intermediate coefficient of friction (μ ∼0.3) but conferred excellent wear protection to mica with no damage from applied loads, F⊥, as high as 300 mN (pressure, P, > 2 MPa). Recombinant rmfp-1/HA coacervates exhibited a comparable coefficient of friction (μ ∼0.3); however, wear protection was significantly inferior (damage at F⊥ > 60 mN) compared with that of native protein coacervates. Wear protection of rmfp-1/HA coacervates increased 5-fold upon addition of the surface adhesive group 3,4-dihydroxyphenylalanine, (Dopa). We propose a Dopa-dependent wear protection mechanism to explain the differences in wear protection between coacervates. Our results reveal a significant untapped potential for coacervates in applications that require adhesion, lubrication, and wear protection. These applications include artificial joints, contact lenses, dental sealants, and hair and skin conditioners.

  12. Fluorescence mapping of mitochondrial TIM23 complex reveals a water-facing, substrate-interacting helix surface.

    Science.gov (United States)

    Alder, Nathan N; Jensen, Robert E; Johnson, Arthur E

    2008-08-08

    Protein translocation across the mitochondrial inner membrane is mediated by the TIM23 complex. While its central component, Tim23, is believed to form a protein-conducting channel, the regions of this subunit that face the imported protein are unknown. To examine Tim23 structure and environment in intact membranes at high resolution, various derivatives, each with a single, environment-sensitive fluorescent probe positioned at a specific site, were assembled into functional TIM23 complexes in active mitochondria and analyzed by multiple spectral techniques. Probes placed sequentially throughout a transmembrane region that was identified by crosslinking as part of the protein-conducting channel revealed an alpha helix in an amphipathic environment. Probes on the aqueous-facing helical surface specifically underwent spectral changes during protein import, and their accessibility to hydrophilic quenching agents is considered in terms of channel gating. This approach has therefore provided an unprecedented view of a translocon channel structure in an intact, fully operational, membrane-embedded complex.

  13. The complex dynamics of the seasonal component of Earth's surface temperature

    Directory of Open Access Journals (Sweden)

    A. Vecchio

    2010-06-01

    Full Text Available The dynamics of the climate system has been investigated by analyzing the complex seasonal oscillation of monthly averaged temperatures recorded at 1167 stations covering the whole USA. We found the presence of an orbit-climate relationship on time scales remarkably shorter than the Milankovitch period related to the nutational forcing. The relationship manifests itself through occasional destabilization of the phase of the seasonal component due to the local changing of balance between direct insolation and the net energy received by the Earth. Quite surprisingly, we found that the local intermittent dynamics is modulated by a periodic component of about 18.6 yr due to the nutation of Earth, which represents the main modulation of the Earth's precession. The global effect in the last century results in a cumulative phase-shift of about 1.74 days towards earlier seasons, in agreement with the phase shift expected from Earth's precession. The climate dynamics of the seasonal cycle can be described through a nonlinear circle-map, indicating that the destabilization process can be associated to intermittent transitions from quasi-periodicity to chaos.

  14. The complex dynamics of the seasonal component of USA's surface temperature

    Directory of Open Access Journals (Sweden)

    A. Vecchio

    2010-10-01

    Full Text Available The dynamics of the climate system has been investigated by analyzing the complex seasonal oscillation of monthly averaged temperatures recorded at 1167 stations covering the whole USA. We found the presence of an orbit-climate relationship on time scales remarkably shorter than the Milankovitch period {related to the nutational forcing}. The relationship manifests itself through occasional destabilization of the phase of the seasonal component due to the local changing of balance between direct insolation and the net energy received by the Earth. Quite surprisingly, we found that the local intermittent dynamics is modulated by a periodic component of about 18.6 yr due to the nutation of the Earth, which represents the main modulation of the Earth's precession. The global effect in the last century results in a cumulative phase-shift of about 1.74 days towards earlier seasons, in agreement with the phase shift expected from the Earth's precession. The climate dynamics of the seasonal cycle can be described through a nonlinear circle-map, indicating that the destabilization process can be associated to intermittent transitions from quasi-periodicity to chaos.

  15. Conformational Explosion: Understanding the Complexity of the Para-Dialkylbenzene Potential Energy Surfaces

    Science.gov (United States)

    Mishra, Piyush; Hewett, Daniel M.; Zwier, Timothy S.

    2017-06-01

    This talk focuses on the single-conformation spectroscopy of small-chain para-dialkylbenzenes. This work builds on previous studies from our group on long-chain n-alkylbenzenes that identified the first folded structure in octylbenzene. The dialkylbenzenes are representative of a class of molecules that are common components of coal and aviation fuel and are known to be present in vehicle exhaust. We bring the molecules para-diethylbenzene, para-dipropylbenzene and para-dibutylbenzene into the gas phase and cool the molecules in a supersonic expansion. The jet-cooled molecules are then interrogated using laser-induced fluorescence excitation, fluorescence dip IR spectroscopy (FDIRS) and dispersed fluorescence. The LIF spectra in the S_{0}-S_{1} origin region show dramatic increases in the number of resolved transitions with increasing length of alkyl chains, reflecting an explosion in the number of unique low-energy conformations formed when two independent alkyl chains are present. Since the barriers to isomerization of the alkyl chain are similar in size, this results in an 'egg carton' shape to the potential energy surface. We use a combination of electronic frequency shift and alkyl CH stretch infrared spectra to generate a consistent set of conformational assignments.

  16. Surface supramolecular organization of a terbium(III) double-decker complex on graphite and its single molecule magnet behavior.

    Science.gov (United States)

    Gonidec, Mathieu; Biagi, Roberto; Corradini, Valdis; Moro, Fabrizio; De Renzi, Valentina; del Pennino, Umberto; Summa, Domenico; Muccioli, Luca; Zannoni, Claudio; Amabilino, David B; Veciana, Jaume

    2011-05-01

    The two-dimensional self-assembly of a terbium(III) double-decker phthalocyanine on highly oriented pyrolitic graphite (HOPG) was studied by atomic force microscopy (AFM), and it was shown that it forms highly regular rectangular two-dimensional nanocrystals on the surface, that are aligned with the graphite symmetry axes, in which the molecules are organized in a rectangular lattice as shown by scanning tunneling microscopy. Molecular dynamics simulations were run in order to model the behavior of a collection of the double-decker complexes on HOPG. The results were in excellent agreement with the experiment, showing that-after diffusion on the graphite surface-the molecules self-assemble into nanoscopic islands which align preferentially along the three main graphite axes. These low dimension assemblies of independent magnetic centers are only one molecule thick (as shown by AFM) and are therefore very interesting nanoscopic magnetic objects, in which all of the molecules are in interaction with the graphite substrate and might therefore be affected by it. The magnetic properties of these self-assembled bar-shaped islands on HOPG were studied by X-ray magnetic circular dichroism, confirming that the compounds maintain their properties as single-molecule magnets when they are in close interaction with the graphite surface.

  17. Surface properties of self-assembled monolayer films of tetra-substituted cobalt, iron and manganese alkylthio phthalocyanine complexes

    Energy Technology Data Exchange (ETDEWEB)

    Akinbulu, Isaac Adebayo; Khene, Samson [Department of Chemistry, Rhodes University, Grahamstown 6140 (South Africa); Nyokong, Tebello, E-mail: t.nyokong@ru.ac.z [Department of Chemistry, Rhodes University, Grahamstown 6140 (South Africa)

    2010-09-30

    Self-assembled monolayer (SAM) films of iron (SAM-1), cobalt (SAM-2) and manganese (SAM-3) phthalocyanine complexes, tetra-substituted with diethylaminoethanethio at the non-peripheral positions, were formed on gold electrode in dimethylformamide (DMF). Electrochemical, impedimentary and surface properties of the SAM films were investigated. Cyclic voltammetry was used to investigate the electrochemical properties of the films. Ability of the films to inhibit common faradaic processes on bare gold surface (gold oxidation, solution redox chemistry of [Fe(H{sub 2}O){sub 6}]{sup 3+}/[Fe(H{sub 2}O){sub 6}]{sup 2+} and underpotential deposition (UDP) of copper) was investigated. Electrochemical impedance spectroscopy (EIS), using [Fe(CN){sub 6}]{sup 3-/4-} redox process as a probe, offered insights into the electrical properties of the films/electrode interfaces. Surface properties of the films were probed using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The films were employed for the electrocatalytic oxidation of the pesticide, carbofuran. Electrocatalysis was evidenced from enhanced current signal and less positive oxidation potential of the pesticide on each film, relative to that observed on the bare gold electrode. Mechanism of electrocatalytic oxidation of the pesticide was studied using rotating disc electrode voltammetry.

  18. Efficient near-real-time monitoring of 3D surface displacements in complex landslide scenarios

    Science.gov (United States)

    Allasia, Paolo; Manconi, Andrea; Giordan, Daniele; Baldo, Marco; Lollino, Giorgio

    2013-04-01

    Ground deformation measurements play a key role in monitoring activities of landslides. A wide spectrum of instruments and methods is nowadays available, going from in-situ to remote sensing approaches. In emergency scenarios, monitoring is often based on automated instruments capable to achieve accurate measurements, possibly with a very high temporal resolution, in order to achieve the best information about the evolution of the landslide in near-real-time, aiming at early warning purposes. However, the available tools for a rapid and efficient exploitation, understanding and interpretation of the retrieved measurements is still a challenge. This issue is particularly relevant in contexts where monitoring is fundamental to support early warning systems aimed at ensuring safety to people and/or infrastructures. Furthermore, in many cases the results obtained might be of difficult reading and divulgation, especially when people of different backgrounds are involved (e.g. scientists, authorities, civil protection operators, decision makers, etc.). In this work, we extend the concept of automatic and near real time from the acquisition of measurements to the data processing and divulgation, in order to achieve an efficient monitoring of surface displacements in landslide scenarios. We developed an algorithm that allows to go automatically and in near-real-time from the acquisition of 3D displacements on a landslide area to the efficient divulgation of the monitoring results via WEB. This set of straightforward procedures is called ADVICE (ADVanced dIsplaCement monitoring system for Early warning), and has been already successfully applied in several emergency scenarios. The algorithm includes: (i) data acquisition and transfer protocols; (ii) data collection, filtering, and validation; (iii) data analysis and restitution through a set of dedicated software, such as ©3DA [1]; (iv) recognition of displacement/velocity threshold and early warning (v) short term

  19. Complex Indigenous Organic Matter Embedded in Apollo 17 Volcanic Black Glass Surface Deposits

    Science.gov (United States)

    Thomas-Keprta, Kathie L.; Clemett, S. J.; Ross, D. K.; Le, L.; Rahman, Z.; Gonzalez, C.; McKay, D. S.; Gibson, E. K.

    2013-01-01

    Papers presented at the first Lunar Science Conference [1] and those published in the subsequent Science Moon Issue [2] reported the C content of Apollo II soils, breccias, and igneous rocks as rang-ing from approx.50 to 250 parts per million (ppm). Later Fegley & Swindle [3] summarized the C content of bulk soils from all the Apollo missions as ranging from 2.5 (Apollo 15) to 280 ppm (Apollo 16) with an overall average of 124+/- 45 ppm. These values are unexpectedly low given that multiple processes should have contributed (and in some cases continue to contribute) to the lunar C inventory. These include exogenous accretion of cometary and asteroidal dust, solar wind implantation, and synthesis of C-bearing species during early lunar volcanism. We estimate the contribution of C from exogenous sources alone is approx.500 ppm, which is approx.4x greater than the reported average. While the assessm ent of indigenous organic matter (OM) in returned lunar samples was one of the primary scientific goals of the Apollo program, extensive analysis of Apollo samples yielded no evidence of any significant indigenous organic species. Furthermore, with such low concentrations of OM reported, the importance of discriminating indigenous OM from terrestrial contamination (e.g., lunar module exhaust, sample processing and handling) became a formidable task. After more than 40 years, with the exception of CH4 [5-7], the presence of indigenous lunar organics still remains a subject of considerable debate. We report for the first time the identification of arguably indigenous OM present within surface deposits of black glass grains collected on the rim of Shorty crater during the Apollo 17 mission by astronauts Eugene Cernan and Harrison Schmitt.

  20. Portrait of the Polana-Eulalia family complex: Surface homogeneity revealed from near-infrared spectroscopy

    Science.gov (United States)

    Pinilla-Alonso, Noemí; de León, J.; Walsh, K. J.; Campins, H.; Lorenzi, V.; Delbo, M.; DeMeo, F.; Licandro, J.; Landsman, Z.; Lucas, M. P.; Alí-Lagoa, V.; Burt, B.

    2016-08-01

    The inner asteroid belt is an important source of near-Earth asteroids (NEAs). Dynamical studies of the inner asteroid belt have identified several families overlapping in proper orbital elements, including the Polana and Eulalia families that contain a large fraction of the low-albedo asteroids in this region. We present results from two coordinated observational campaigns to characterize this region through near-infrared (NIR) spectroscopy. These campaigns ran from August 2012 to May 2014 and used the NASA Infrared Telescope Facility and the Telescopio Nazionale Galileo. The observations focused on objects within these families or in the background, with low albedo (pv ≤ 0.1) and low inclination (iP ≤ 7°). We observed 63 asteroids (57 never before observed in the NIR): 61 low-albedo objects and two interlopers, both compatible with S- or E- taxonomical types. We found our sample to be spectrally homogeneous in the NIR. The sample shows a continuum of neutral to moderately-red concave-up spectra, very similar within the uncertainties. Only one object in the sample, asteroid (3429) Chuvaev, has a blue spectrum, with a slope (S‧ = - 1.33 ± 0.21%/1000 Å) significantly different from the average spectrum (S‧ = 0.68 ± 0.68%/1000 Å). This spectral homogeneity is independent of membership in families or the background population. Furthermore, we show that the Eulalia and Polana families cannot be distinguished using NIR data. We also searched for rotational variability on the surface of (495) Eulalia which we do not detect. (495) Eulalia shows a red concave-up spectrum with an average slope S‧ = 0.91 ± 0.60%/1000 Å, very similar to the average slope of our sample. The spectra of two targets of sample-return missions, (101955) Bennu, target of NASA's OSIRIS-Rex and (162173) 1999 JU3 target of the Japanese Space Agency's Hayabusa-2, are very similar to our average spectrum, which would be compatible with an origin in this region of the inner belt.

  1. Ab Initio Exploration of the Potential Energy Surface of the O_2-SO_2 Open-Shell Complex.

    Science.gov (United States)

    Fawzy, Wafaa M.; Hougen, Jon T.

    2016-06-01

    The O_2-SO_2 complex is believed to be a precursor to acid rain. The previously observed FTMW spectrum suggested internal motions within the complex, but their nature was not identified. Development of an effective Hamiltonian for an open-shell molecule with tunneling requires knowledge of the potential energy surface (PES) and the intrinsic reaction coordinates (IRC) for the paths between minima. A recent ab initio study reported two different nonplanar minima in the ground electronic state of O_2-SO_2. These predictions were based on geometry optimization calculations at the MP2/aug-cc-pVnZ level of theory, with n = 2 and 3. The current work is focused on a highly correlated ab initio investigation of the global PES (a 9-D problem) in the ground triplet electronic state of O_2-SO_2. Because of the high dimensionality in the complex, the PES calculations are partitioned into several two-dimensional cuts through the PES. We have so far explored only a 3-D part of the global PES to look for stable planar configurations. These calculations included geometry optimization, frequency, and single point energy calculations. Calculations were performed using UCCSD(T)/aug-cc-pV(n+D)Z,where n = 2 and 3, level of theory. We used an axis system that defines the radial and the angular van der Waals coordinates for a planar complex as RvW, θ_1, and θ_2. The bond length (RvW) is the distance between the center of mass of the O_2 unit and the S atom. θ_1 and θ_2 are the angles between the van der Waals bond and the O_2 internuclear axis or one of the SO bonds in the SO_2 moiety, respectively. Full geometry optimization calculations predicted a minimum of C_s symmetry in which both the O_2 and SO_2 units are tilted with respect to the van der Waals bond, and RvW = 3.63 {Å}. 3-D PES surface calculations, which involve the RvW, θ_1, and θ_2 vdW coordinates, showed that the optimized structure is the global minimum. In addition, a local minimum at RvW = 3.9 {Å}, which

  2. Inner-sphere complexation of cations at the rutile-water interface: A concise surface structural interpretation with the CD and MUSIC model

    NARCIS (Netherlands)

    Ridley, M.K.; Hiemstra, T.; Riemsdijk, van W.H.; Machesky, M.L.

    2009-01-01

    Acid–base reactivity and ion-interaction between mineral surfaces and aqueous solutions is most frequently investigated at the macroscopic scale as a function of pH. Experimental data are then rationalized by a variety of surface complexation models. These models are thermodynamically based which in

  3. Stability of engineered nanomaterials in complex aqueous matrices: Settling behaviour of CeO2 nanoparticles in natural surface waters.

    Science.gov (United States)

    Van Koetsem, Frederik; Verstraete, Simon; Van der Meeren, Paul; Du Laing, Gijs

    2015-10-01

    The stability of engineered nanoparticles (ENPs) in complex aqueous matrices is a key determinant of their fate and potential toxicity towards the aquatic environment and human health. Metal oxide nanoparticles, such as CeO2 ENPs, are increasingly being incorporated into a wide range of industrial and commercial applications, which will undoubtedly result in their (unintentional) release into the environment. Hereby, the behaviour and fate of CeO2 ENPs could potentially serve as model for other nanoparticles that possess similar characteristics. The present study examined the stability and settling of CeO2 ENPs (7.3±1.4 nm) as well as Ce(3+) ions in 10 distinct natural surface waters during 7d, under stagnant and isothermal experimental conditions. Natural water samples were collected throughout Flanders (Belgium) and were thoroughly characterized. For the majority of the surface waters, a substantial depletion (>95%) of the initially added CeO2 ENPs was observed just below the liquid surface of the water samples after 7d. In all cases, the reduction was considerably higher for CeO2 ENPs than for Ce(3+) ions (CeO2 ENPs (R(2)≥0.998) and Ce(3+) ions (R(2)≥0.812) from the water column, at least in case notable sedimentation occurred over time. Solution-pH appeared to be a prime parameter governing nanoparticle colloidal stability. Moreover, the suspended solids (TSS) content also seemed to be an important factor affecting the settling rate and residual fraction of CeO2 ENPs as well as Ce(3+) ions in natural surface waters. Correlation results also suggest potential association and co-precipitation of CeO2 ENPs with aluminium- and iron-containing natural colloidal material. The CeO2 ENPs remained stable in dispersion in surface water characterized by a low pH, ionic strength (IS), and TSS content, indicating the eventual stability and settling behaviour of the nanoparticles was likely determined by a combination of physicochemical parameters. Finally, ionic

  4. Role of Polysaccharides in Complex Mixtures with Soy Protein Hydrolysate on Foaming Properties Studied by Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Karina D. Martínez

    2014-01-01

    Full Text Available The complex mixture studied, a hydrolyzed soy protein (HSP, κ-carrageenan (κC, and an hydroxypropyl methylcellulose (HPMC, could be used as a foaming agent under refrigeration or heating conditions because of the presence of one polysaccharide (HPMC that gels on heating and another (κC that gels on cooling. The objective of this work was to study the role of these polysaccharides on foaming properties by whipping methods at heating conditions. For this purpose, response surface methodology was used to optimize the mixed product in foamed food systems. The obtained results showed that the combination of E4M, κC, and HSP is an adequate strategy to generate good foam capacity and stability at heating conditions. The huge stability increase of foams at heating conditions was ascribed to combined effect of polysaccharides: gelling property of E4M and the viscozieng character imparted by κC to continuous phase of foaming.

  5. New insights into saline water evaporation from porous media: Complex interaction between evaporation rates, precipitation, and surface temperature

    Science.gov (United States)

    Shokri-Kuehni, Salomé M. S.; Vetter, Thomas; Webb, Colin; Shokri, Nima

    2017-06-01

    Understanding salt transport and deposition patterns during evaporation from porous media is important in many engineering and hydrological processes such as soil salinization, ecosystem functioning, and land-atmosphere interaction. As evaporation proceeds, salt concentration increases until it exceeds solubility limits, locally, and crystals precipitate. The interplay between transport processes, crystallization, and evaporation influences where crystallization occurs. During early stages, the precipitated salt creates an evolving porous structure affecting the evaporation kinetics. We conducted a comprehensive series of experiments to investigate how the salt concentration and precipitation influence evaporation dynamics. Our results illustrate the contribution of the evolving salt crust to the evaporative mass losses. High-resolution thermal imaging enabled us to investigate the complex temperature dynamics at the surface of precipitated salt, providing further confirmation of salt crust contribution to the evaporation. We identify different phases of saline water evaporation from porous media with the corresponding dominant mechanisms in each phase and extend the physical understanding of such processes.

  6. Synthesis of nanoparticle/ligand composite thin films by sequential ligand self assembly and surface complex reduction.

    Science.gov (United States)

    Muench, Falk; Fuchs, Anne; Mankel, Eric; Rauber, Markus; Lauterbach, Stefan; Kleebe, Hans-Joachim; Ensinger, Wolfgang

    2013-01-01

    Nanocomposite thin films consisting of ligand-connected metal nanoparticles were deposited by iteration of ligand assembly, surface complex formation and reduction. This novel and convenient approach combines characteristics of the layer-by-layer (LbL) and the successive ion layer adsorption and reaction (SILAR) techniques. In contrast to classical LbL assembly, the nanoparticle formation is performed in situ, avoiding separate reduction, protection and attachment steps. To demonstrate the versatility of the approach, different metal precursors (Pd, Ag and Au salts) and linkers (1,2-ethanedithiol, 1,4-benzenedithiol and polythiol) were applied. The formation of dithiol-linked nanoparticle films was confirmed by TEM and XPS. By combining the deposition protocol with ion track etched polycarbonate templates, nanotubes and nanowires with high aspect ratios of up to 300 could be fabricated.

  7. Neptunium (V) Adsorption to a Halophilic Bacterium Under High Ionic Strength Conditions: A Surface Complexation Modeling Approach

    Energy Technology Data Exchange (ETDEWEB)

    Ams, David A [Los Alamos National Laboratory

    2012-06-11

    Rationale for experimental design: Np(V) -- important as analog for Pu(V) and for HLW scenarios; High ionic strength -- relevant to salt-based repositories such as the WIPP; Halophilic microorganisms -- representative of high ionic strength environments. For the first time showed: Significant adsorbant to halophilic microorganisms over entire pH range under high ionic strength conditions; Strong influence of ionic strength with increasing adsorption with increasing ionic strength (in contrast to trends of previous low ionic strength studies); Effect of aqueous Np(V) and bacterial surface site speciation on adsorption; and Developed thermodynamic models that can be incorporated into geochemical speciation models to aid in the prediction of the fate and transport of Np(V) in more complex systems.

  8. Emission of near-zero energy electrons from the surface of a source with complex radionuclide composition

    CERN Document Server

    Kupryashkyin, V T; Feoktistov, O Y; Shapovalova, Y P

    2002-01-01

    The emission of near-zero energy electrons e sub 0 from the surface of a source with complex radionuclide composition is investigated by the (e gamma)-coincidence method. Yields of e sub 0 -electrons a determined in beta-decay, electron capture, and internal conversion of gamma-rays for radionuclides which were created as admixtures in the thin layer of Pt and Al substrate after irradiation by neutrons in a reactor. The density distribution of radionuclides over the thickness of the Pt layer is determined. The developed (e gamma)-coincidence method allows one to investigate e sub 0 -electron emission for admixed radionuclides whose contents are a few hundredths of percent.

  9. Theoretical investigation of potential energy surface and bound states for the van der Waals complex Ar–BrCl dimer

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Rui [School of Mathematics and Information Science, North China University of Water Resources and Electric Power, Zhengzhou (China); Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan (China); Li, Song, E-mail: lsong@yangtzeu.edu.cn [School of Physics and Optoelectronic Engineering, Yangtze University, Jingzhou (China); Chen, Shan-Jun; Chen, Yan [School of Physics and Optoelectronic Engineering, Yangtze University, Jingzhou (China); Zheng, Li-Min [Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan (China)

    2015-09-08

    Highlights: • A two-dimensional potential for Ar–BrCl is constructed at the CCSD(T) level. • The PES is characterized by three minima and two saddle points between them. • Bound state calculations were carried out for the complex. - Abstract: The intermolecular potential energy surface (PES) of the ground electronic state for the Ar–BrCl dimer is constructed at the CCSD(T) level with the aug-cc-pVQZ basis set and mid-bond functions. The PES is characterized by three minima and two saddle points. The global minimum corresponding to a collinear Ar–BrCl configuration, which has been observed experimentally, is located at R = 4.10 Å and θ = 2.5° with a well depth of −285.207 cm{sup −1}. A nearly T-shaped structure and an anti-linear Ar–ClBr geometry is also predicted. The bound state calculations are preformed to study intermolecular vibrational modes, rotational levels and average structures for the complex. Our transition frequencies, spectroscopic constants and average structures for all isotopomers of the collinear isomer agree well with experimental data. We have also provided pure rotational transitional frequencies for both nearly T-shaped and anti-linear isomers. These results are significant for further experimental investigations of the Ar–BrCl dimer.

  10. Potential energy surface of the CO{sub 2}–N{sub 2} van der Waals complex

    Energy Technology Data Exchange (ETDEWEB)

    Nasri, Sameh; Ajili, Yosra [Laboratoire de Spectroscopie Atomique, Moléculaire et Applications-LSAMA, Université de Tunis El Manar, Tunis (Tunisia); Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallée (France); Jaidane, Nejm-Eddine [Laboratoire de Spectroscopie Atomique, Moléculaire et Applications-LSAMA, Université de Tunis El Manar, Tunis (Tunisia); Kalugina, Yulia N. [Department of Optics and Spectroscopy, Tomsk State University, 36 Lenin Ave., Tomsk 634050 (Russian Federation); Halvick, Philippe; Stoecklin, Thierry [Institut des Sciences Moléculaires, Université de Bordeaux, CNRS UMR 5255, 33405 Talence Cedex (France); Hochlaf, Majdi, E-mail: hochlaf@univ-mlv.fr [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallée (France)

    2015-05-07

    Four-dimensional potential energy surface (4D-PES) of the atmospherically relevant CO{sub 2}–N{sub 2} van der Waals complex is generated using the explicitly correlated coupled cluster with single, double, and perturbative triple excitation (CCSD(T)-F12) method in conjunction with the augmented correlation consistent triple zeta (aug-cc-pVTZ) basis set. This 4D-PES is mapped along the intermonomer coordinates. An analytic fit of this 4D-PES is performed. Our extensive computations confirm that the most stable form corresponds to a T-shape structure where the nitrogen molecule points towards the carbon atom of CO{sub 2}. In addition, we located a second isomer and two transition states in the ground state PES of CO{sub 2}–N{sub 2}. All of them lay below the CO{sub 2} + N{sub 2} dissociation limit. This 4D-PES is flat and strongly anisotropic along the intermonomer coordinates. This results in the possibility of the occurrence of large amplitude motions within the complex, such as the inversion of N{sub 2}, as suggested in the recent spectroscopic experiments. Finally, we show that the experimentally established deviations from the C{sub 2v} structure at equilibrium for the most stable isomer are due to the zero-point out-of-plane vibration correction.

  11. Synthesis, structural characterization, Hirshfeld surface analysis and spectroscopic studies of cadmium (II) chloride complex with 4-hydroxy-1-methylpiperidine

    Science.gov (United States)

    Soudani, S.; Ferretti, V.; Jelsch, C.; Lefebvre, F.; Nasr, C. Ben

    2016-05-01

    The chemical preparation, crystal structure, Hirshfeld surface analysis and spectroscopic characterization of the novel cadmium (II) 4-hydroxy-1-methylpiperidine complex, Cd4Cl10(C6H14NO)2·2H2O, have been reported. The atomic arrangement can be described as built up by an anionic framework, formed by edge sharing CdCl6 and CdCl5O octahedral linear chains spreading along the a-axis. These chains are interconnected by water molecules via O-H⋯Cl and O-H⋯O hydrogen bonds to form layers parallel to (011) plane. The organic cations are inserted between layers through C-H⋯Cl hydrogen bonds. Investigation of intermolecular interactions and crystal packing via Hirshfeld surface analysis reveals that the HC⋯Cl and HC⋯HC intermolecular interactions are the most abundant contacts of the organic cation in the crystal packing. The statistical analysis of crystal contacts reveals the driving forces in the packing formation. The 13C and 15N CP-MAS NMR spectra are in agreement with the X-ray structure. The vibrational absorption bands were identified by infrared spectroscopy. DFT calculations allowed the attribution of the NMR peaks and of the IR bands.

  12. Grain-Size Based Additivity Models for Scaling Multi-rate Uranyl Surface Complexation in Subsurface Sediments

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaoying; Liu, Chongxuan; Hu, Bill X.; Hu, Qinhong

    2016-07-31

    The additivity model assumed that field-scale reaction properties in a sediment including surface area, reactive site concentration, and reaction rate can be predicted from field-scale grain-size distribution by linearly adding reaction properties estimated in laboratory for individual grain-size fractions. This study evaluated the additivity model in scaling mass transfer-limited, multi-rate uranyl (U(VI)) surface complexation reactions in a contaminated sediment. Experimental data of rate-limited U(VI) desorption in a stirred flow-cell reactor were used to estimate the statistical properties of the rate constants for individual grain-size fractions, which were then used to predict rate-limited U(VI) desorption in the composite sediment. The result indicated that the additivity model with respect to the rate of U(VI) desorption provided a good prediction of U(VI) desorption in the composite sediment. However, the rate constants were not directly scalable using the additivity model. An approximate additivity model for directly scaling rate constants was subsequently proposed and evaluated. The result found that the approximate model provided a good prediction of the experimental results within statistical uncertainty. This study also found that a gravel-size fraction (2 to 8 mm), which is often ignored in modeling U(VI) sorption and desorption, is statistically significant to the U(VI) desorption in the sediment.

  13. Three-channel false colour AFM images for improved interpretation of complex surfaces: a study of filamentous cyanobacteria.

    Science.gov (United States)

    Kurk, Toby; Adams, David G; Connell, Simon D; Thomson, Neil H

    2010-05-01

    Imaging signals derived from the atomic force microscope (AFM) are typically presented as separate adjacent images with greyscale or pseudo-colour palettes. We propose that information-rich false-colour composites are a useful means of presenting three-channel AFM image data. This method can aid the interpretation of complex surfaces and facilitate the perception of information that is convoluted across data channels. We illustrate this approach with images of filamentous cyanobacteria imaged in air and under aqueous buffer, using both deflection-modulation (contact) mode and amplitude-modulation (tapping) mode. Topography-dependent contrast in the error and tertiary signals aids the interpretation of the topography signal by contributing additional data, resulting in a more detailed image, and by showing variations in the probe-surface interaction. Moreover, topography-independent contrast and topography-dependent contrast in the tertiary data image (phase or friction) can be distinguished more easily as a consequence of the three dimensional colour-space.

  14. Complexes of hepatitis B surface antigen and immunoglobulin M in the sera of patients with hepatitis B virus infection.

    Science.gov (United States)

    Palla, M; Rizzi, R; Toti, M; Almi, P; Rizzetto, M; Bonino, F; Purcell, R

    1983-01-01

    Hepatitis B surface antigen (HBsAg) bound to immunoglobulin M (IgM) was detected in sera of HBsAg carriers by a radioimmunoassay based on selective absorption of the immunoglobulin on a solid phase coated with antiserum to human IgM. Isopycnic banding and rate-zonal sedimentation have shown that the reaction is related to particulate forms of the HBsAg complexed with IgM. The binding of IgM possibly occurred because of a selective affinity of these molecules to the surface of HBsAg particles. HBsAg/IgM was found transiently in 24 of 25 (96%) patients with acute self-limited hepatitis B and persistently in 6 of 25 patients whose acute hepatitis B progressed to chronicity. It was also found in 20 of 39 (51%) chronic HBsAg carriers with inactive and asymptomatic infection. The HBsAg/IgM phenomenon is not dependent on replication of hepatitis B virions; its persistence in patients with acute hepatitis B may provide complementary evidence of transition of the infection to chronicity. PMID:6309673

  15. Synthesis, structural characterization, Hirshfeld surface analysis and spectroscopic studies of cadmium (II) chloride complex with 4-hydroxy-1-methylpiperidine

    Energy Technology Data Exchange (ETDEWEB)

    Soudani, S. [Université de Carthage, Laboratoire de Chimie des Matériaux, Faculté des Sciences de Bizerte, 7021 Zarzouna (Tunisia); Ferretti, V. [Department of Chemical and Pharmaceutical Sciences and Center for Structural Diffractometry, via Fossato di Mortara 17, I-44121 Ferrara (Italy); Jelsch, C. [CRM2, CNRS, Institut Jean Barriol, Université de Lorraine, Vandoeuvre les Nancy CEDEX (France); Lefebvre, F. [Laboratoire de Chimie Organométallique de Surface (LCOMS), Ecole Supérieure de Chimie Physique Electronique, 69626 Villeurbanne Cedex (France); Nasr, C. Ben, E-mail: cherif_bennasr@yahoo.fr [Université de Carthage, Laboratoire de Chimie des Matériaux, Faculté des Sciences de Bizerte, 7021 Zarzouna (Tunisia)

    2016-05-15

    The chemical preparation, crystal structure, Hirshfeld surface analysis and spectroscopic characterization of the novel cadmium (II) 4-hydroxy-1-methylpiperidine complex, Cd{sub 4}Cl{sub 10}(C{sub 6}H{sub 14}NO){sub 2}·2H{sub 2}O, have been reported. The atomic arrangement can be described as built up by an anionic framework, formed by edge sharing CdCl{sub 6} and CdCl{sub 5}O octahedral linear chains spreading along the a-axis. These chains are interconnected by water molecules via O–H⋯Cl and O–H⋯O hydrogen bonds to form layers parallel to (011) plane. The organic cations are inserted between layers through C–H⋯Cl hydrogen bonds. Investigation of intermolecular interactions and crystal packing via Hirshfeld surface analysis reveals that the H{sub C}⋯Cl and H{sub C}⋯H{sub C} intermolecular interactions are the most abundant contacts of the organic cation in the crystal packing. The statistical analysis of crystal contacts reveals the driving forces in the packing formation. The {sup 13}C and {sup 15}N CP-MAS NMR spectra are in agreement with the X-ray structure. The vibrational absorption bands were identified by infrared spectroscopy. DFT calculations allowed the attribution of the NMR peaks and of the IR bands.

  16. Mechanisms influencing surface soil CO2 efflux in respect to elevation and vegetation gradients in a complex watershed

    Science.gov (United States)

    Atkins, J. W.; Epstein, H. E.; Welsch, D. L.

    2011-12-01

    Topographically complex watersheds exert spatial and temporal variations in the distribution of soil water due to horizontal flows. The redistribution of soil water has profound effects on biogeochemical cycles. Of keen interest is the impact this lateral redistribution has on carbon cycling and surface soil carbon efflux. We are currently employing a plot based study across an elevation gradient (950-1150 m) in the Weimer Run watershed located near Davis, West Virginia to evaluate carbon and water cycling dynamics. At each of three different elevation levels (high, middle, low) are three sites. At each site are three 4 m2 plots, each underneath a different vegetation cover type (open, closed tree canopy, shrub canopy), for a total of 27 plots across all elevations. At each plot, surface CO2 efflux, soil temperature, PAR, air temperature and volumetric soil water content at 0-12 cm are measured weekly during the growing season. Measurements of Leaf Area Index (LAI) and soil nutrient concentrations (NH4+, NO3-) have also been conducted for each plot. Each plot also has gas wells at both 5 and 20 cm to measure CO2 concentrations below the soil surface. Data collected from June through October, 2010, indicate a stronger control on soil CO2 efflux exerted by vegetation cover type than by elevation gradient. The impact of vegetation cover type on soil CO2 efflux increases with elevation. Based on data collected weekly from June through October, 2010, there is no significant relationship between surface soil CO2 efflux and the three elevation levels within our gradient (p = 0.47). However, a significant statistical relationship between surface soil CO2 efflux and vegetation type (p = impact that vegetation cover, elevation and micrometeorological controls exert on soil CO2 efflux is vital for accurate model inputs and carbon budgets.class="jpg" border=0 width=600px src="/meetings/fm11/program/tables/B33F-0525_T1.jpg"> * All values in columns represent means for

  17. Surface stabilized GMR nanorods of silver coated CrO{sub 2} synthesized via a polymer complex at ambient pressure

    Energy Technology Data Exchange (ETDEWEB)

    Biswas, S., E-mail: drsomnathbiswas@gmail.com [The LNM Institute of Information Technology, Jaipur-302031 (India); Singh, G.P. [Centre for Nanotechnology, Central University of Jharkhand, Ranchi-835205 (India); Ram, S. [Materials Science Centre, Indian Institute of Technology, Kharagpur-721302 (India); Fecht, H.-J. [Insitut für Micro-und Nanomaterialien, Universität Ulm, Albert Einstein Allee-47, Ulm, D-89081, and Forschungszentrum Karlsruhe, Institute of Nanotechnology, Karlsruhe, D-76021 (Germany)

    2013-08-15

    Stable anisotropic nanorods of surface modified CrO{sub 2} (∼18 nm diameter) with a correlated diamagnetic layer (2–3 nm thickness) of silver efficiently tailors useful magnetic and magnetoresistance (MR) properties. Essentially, it involves a core-shell structure that is developed by displacing part of Cr{sup 4+} ions by Ag atoms on the CrO{sub 2} surface (topotactic surface layer) via an etching reaction of a CrO{sub 2}-polymer complex with Ag{sup +} ions in hot water followed by heating the dried sample at 300–400 °C in air. The stable Ag-layer so obtained in the form of a shell protects CrO{sub 2} such that it no longer converts to Cr{sub 2}O{sub 3} in ambient pressure during the processing. X-ray diffractogram of the Rutile type tetragonal CrO{sub 2} structure (lattice parameters a=0.4429 nm and c=0.2950 nm) includes weak peaks of a minority phase of an fcc-Ag (a=0.4086 nm). The silver surface layer, which manifests itself in a doublet of the 3d{sub 5/2} and 3d{sub 3/2} X-ray photoelectron bands of binding energies 368.46 eV and 374.48 eV, respectively, suppresses almost all Cr bands to appear in a measurable intensity. The sample exhibits a distinctly enhanced MR-value, e.g., (−) 7.6% at 77 K, than reported values in compacted CrO{sub 2} powders or composites. Such a large MR-value in the Coulomb blockade regime (<100 K) arises not only due to the suppressed spin flipping at low temperature but also from a spin dependent co-tunneling through an interlinked structure of silver and silver coated CrO{sub 2} nanorods. - Highlights: • Synthesis and structural studies of a novel GMR material of Ag coated CrO{sub 2}. • Tailoring useful GMR property in CrO{sub 2} nanorods of controlled shape and anisotropy. • Enhanced GMR is explained in correlation to the surface structure of CrO{sub 2} nanorods.

  18. Study of solid/liquid and solid/gas interfaces in Cu–isoleucine complex by surface X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Ferrer, Pilar, E-mail: ferreres@esrf.fr [SpLine Spanish CRG Beamline at the ESRF, 38000 Grenoble (France); Instituto de Ciencia de Materiales de Madrid, 28049 Madrid (Spain); Rubio-Zuazo, Juan; Castro, German R. [SpLine Spanish CRG Beamline at the ESRF, 38000 Grenoble (France); Instituto de Ciencia de Materiales de Madrid, 28049 Madrid (Spain)

    2013-02-15

    The enzymes could be understood like structures formed by amino acids bonded with metals, which act as active sites. The research on the coordination of metal–amino acid complexes will bring light on the behavior of metal enzymes, due to the close relation existing between the atomic structure and the functionality. The Cu–isoleucine bond is considered as a good model system to attain a better insight into the characteristics of naturally occurring copper metalloproteins. The surface structure of metal–amino acid complex could be considered as a more realistic model for real systems under biologic working conditions, since the molecular packing is decreased. In the surface, the structural constrains are reduced, keeping the structural capability of surface complex to change as a function of the surrounding environment. In this work, we present a surface X-ray diffraction study on Cu–isoleucine complex under different ambient conditions. Cu(Ile){sub 2} crystals of about 5 mm × 5 mm × 1 mm have been growth, by seeding method in a supersaturated solution, presenting a surface of high quality. The sample for the surface diffraction study was mounted on a cell specially designed for solid/liquid or solid/gas interface analysis. The Cu–isoleucine crystal was measured under a protective dry N{sub 2} gas flow and in contact with a saturated metal amino acid solution. The bulk and the surface signals were compared, showing different atomic structures. In both cases, from surface diffraction data, it is observed that the atomic structure of the top layer undergoes a clear structural deformation. A non-uniform surface relaxation is observed producing an inhomogeneous displacement of the surface atoms towards the surface normal.

  19. Study of solid/liquid and solid/gas interfaces in Cu-isoleucine complex by surface X-ray diffraction

    Science.gov (United States)

    Ferrer, Pilar; Rubio-Zuazo, Juan; Castro, German R.

    2013-02-01

    The enzymes could be understood like structures formed by amino acids bonded with metals, which act as active sites. The research on the coordination of metal-amino acid complexes will bring light on the behavior of metal enzymes, due to the close relation existing between the atomic structure and the functionality. The Cu-isoleucine bond is considered as a good model system to attain a better insight into the characteristics of naturally occurring copper metalloproteins. The surface structure of metal-amino acid complex could be considered as a more realistic model for real systems under biologic working conditions, since the molecular packing is decreased. In the surface, the structural constrains are reduced, keeping the structural capability of surface complex to change as a function of the surrounding environment. In this work, we present a surface X-ray diffraction study on Cu-isoleucine complex under different ambient conditions. Cu(Ile)2 crystals of about 5 mm × 5 mm × 1 mm have been growth, by seeding method in a supersaturated solution, presenting a surface of high quality. The sample for the surface diffraction study was mounted on a cell specially designed for solid/liquid or solid/gas interface analysis. The Cu-isoleucine crystal was measured under a protective dry N2 gas flow and in contact with a saturated metal amino acid solution. The bulk and the surface signals were compared, showing different atomic structures. In both cases, from surface diffraction data, it is observed that the atomic structure of the top layer undergoes a clear structural deformation. A non-uniform surface relaxation is observed producing an inhomogeneous displacement of the surface atoms towards the surface normal.

  20. Surface complexation and precipitate geometry for aqueous Zn(II) sorption on ferrihydrite: II. XANES analysis and simulation

    Science.gov (United States)

    Waychunas, G.A.; Fuller, C.C.; Davis, J.A.; Rehr, J.J.

    2003-01-01

    X-ray absorption near-edge spectroscopy (XANES) analysis of sorption complexes has the advantages of high sensitivity (10- to 20-fold greater than extended X-ray absorption fine structure [EXAFS] analysis) and relative ease and speed of data collection (because of the short k-space range). It is thus a potentially powerful tool for characterization of environmentally significant surface complexes and precipitates at very low surface coverages. However, quantitative analysis has been limited largely to "fingerprint" comparison with model spectra because of the difficulty of obtaining accurate multiple-scattering amplitudes for small clusters with high confidence. In the present work, calculations of the XANES for 50- to 200-atom clusters of structure from Zn model compounds using the full multiple-scattering code Feff 8.0 accurately replicate experimental spectra and display features characteristic of specific first-neighbor anion coordination geometry and second-neighbor cation geometry and number. Analogous calculations of the XANES for small molecular clusters indicative of precipitation and sorption geometries for aqueous Zn on ferrihydrite, and suggested by EXAFS analysis, are in good agreement with observed spectral trends with sample composition, with Zn-oxygen coordination and with changes in second-neighbor cation coordination as a function of sorption coverage. Empirical analysis of experimental XANES features further verifies the validity of the calculations. The findings agree well with a complete EXAFS analysis previously reported for the same sample set, namely, that octahedrally coordinated aqueous Zn2+ species sorb as a tetrahedral complex on ferrihydrite with varying local geometry depending on sorption density. At significantly higher densities but below those at which Zn hydroxide is expected to precipitate, a mainly octahedral coordinated Zn2+ precipitate is observed. An analysis of the multiple scattering paths contributing to the XANES

  1. The Utility of Remotely-Sensed Land Surface Temperature from Multiple Platforms For Testing Distributed Hydrologic Models over Complex Terrain

    Science.gov (United States)

    Xiang, T.; Vivoni, E. R.; Gochis, D. J.

    2011-12-01

    for testing distributed hydrologic models in regions of complex terrain with seasonal changes in land surface conditions.

  2. Effect of pullulan nanoparticle surface charges on HSA complexation and drug release behavior of HSA-bound nanoparticles.

    Directory of Open Access Journals (Sweden)

    Xiaojun Tao

    Full Text Available Nanoparticle (NP compositions such as hydrophobicity and surface charge are vital to determine the presence and amount of human serum albumin (HSA binding. The HSA binding influences drug release, biocompatibility, biodistribution, and intercellular trafficking of nanoparticles (NPs. Here, we prepared 2 kinds of nanomaterials to investigate HSA binding and evaluated drug release of HSA-bound NPs. Polysaccharides (pullulan carboxyethylated to provide ionic derivatives were then conjugated to cholesterol groups to obtain cholesterol-modified carboxyethyl pullulan (CHCP. Cholesterol-modified pullulan (CHP conjugate was synthesized with a similar degree of substitution of cholesterol moiety to CHCP. CHCP formed self-aggregated NPs in aqueous solution with a spherical structure and zeta potential of -19.9 ± 0.23 mV, in contrast to -1.21 ± 0.12 mV of CHP NPs. NPs could quench albumin fluorescence intensity with maximum emission intensity gradually decreasing up to a plateau at 9 to 12 h. Binding constants were 1.12 × 10(5 M(-1 and 0.70 × 10(5 M(-1 to CHP and CHCP, respectively, as determined by Stern-Volmer analysis. The complexation between HSA and NPs was a gradual process driven by hydrophobic force and inhibited by NP surface charge and shell-core structure. HSA conformation was altered by NPs with reduction of α-helical content, depending on interaction time and particle surface charges. These NPs could represent a sustained release carrier for mitoxantrone in vitro, and the bound HSA assisted in enhancing sustained drug release.

  3. Effect of Pullulan Nanoparticle Surface Charges on HSA Complexation and Drug Release Behavior of HSA-Bound Nanoparticles

    Science.gov (United States)

    Tao, Xiaojun; Zhang, Qiufang; Ling, Kai; Chen, Yicun; Yang, Wenzhi; Gao, Fenfei; Shi, Ganggang

    2012-01-01

    Nanoparticle (NP) compositions such as hydrophobicity and surface charge are vital to determine the presence and amount of human serum albumin (HSA) binding. The HSA binding influences drug release, biocompatibility, biodistribution, and intercellular trafficking of nanoparticles (NPs). Here, we prepared 2 kinds of nanomaterials to investigate HSA binding and evaluated drug release of HSA-bound NPs. Polysaccharides (pullulan) carboxyethylated to provide ionic derivatives were then conjugated to cholesterol groups to obtain cholesterol-modified carboxyethyl pullulan (CHCP). Cholesterol-modified pullulan (CHP) conjugate was synthesized with a similar degree of substitution of cholesterol moiety to CHCP. CHCP formed self-aggregated NPs in aqueous solution with a spherical structure and zeta potential of −19.9±0.23 mV, in contrast to −1.21±0.12 mV of CHP NPs. NPs could quench albumin fluorescence intensity with maximum emission intensity gradually decreasing up to a plateau at 9 to 12 h. Binding constants were 1.12×105 M−1 and 0.70×105 M−1 to CHP and CHCP, respectively, as determined by Stern-Volmer analysis. The complexation between HSA and NPs was a gradual process driven by hydrophobic force and inhibited by NP surface charge and shell-core structure. HSA conformation was altered by NPs with reduction of α-helical content, depending on interaction time and particle surface charges. These NPs could represent a sustained release carrier for mitoxantrone in vitro, and the bound HSA assisted in enhancing sustained drug release. PMID:23166632

  4. Effect of surface conditioning modalities on the repair bond strength of resin composite to the zirconia core / veneering ceramic complex.

    Science.gov (United States)

    Ozcan, Mutlu; Valandro, Luiz Felipe; Pereira, Sarina Maciel; Amaral, Regina; Bottino, Marco Antonio; Pekkan, Gurel

    2013-06-01

    This study evaluated the effect of different surface conditioning protocols on the repair strength of resin composite to the zirconia core / veneering ceramic complex, simulating the clinical chipping phenomenon. Forty disk-shaped zirconia core (Lava Zirconia, 3M ESPE) (diameter: 3 mm) specimens were veneered circumferentially with a feldspathic veneering ceramic (VM7, Vita Zahnfabrik) (thickness: 2 mm) using a split metal mold. They were then embedded in autopolymerizing acrylic with the bonding surfaces exposed. Specimens were randomly assigned to one of the following surface conditioning protocols (n = 10 per group): group 1, veneer: 4% hydrofluoric acid (HF) (Porcelain Etch) + core: aluminum trioxide (50-µm Al2O3) + core + veneer: silane (ESPE-Sil); group 2: core: Al2O3 (50 µm) + veneer: HF + core + veneer: silane; group 3: veneer: HF + core: 30 µm aluminum trioxide particles coated with silica (30 µm SiO2) + core + veneer: silane; group 4: core: 30 µm SiO2 + veneer: HF + core + veneer: silane. Core and veneer ceramic were conditioned individually but no attempt was made to avoid cross contamination of conditioning, simulating the clinical intraoral repair situation. Adhesive resin (VisioBond) was applied to both the core and the veneer ceramic, and resin composite (Quadrant Posterior) was bonded onto both substrates using polyethylene molds and photopolymerized. After thermocycling (6000 cycles, 5°C-55°C), the specimens were subjected to shear bond testing using a universal testing machine (1 mm/min). Failure modes were identified using an optical microscope, and scanning electron microscope images were obtained. Bond strength data (MPa) were analyzed statistically using the non-parametric Kruskal-Wallis test followed by the Wilcoxon rank-sum test and the Bonferroni Holm correction (α = 0.05). Group 3 demonstrated significantly higher values (MPa) (8.6 ± 2.7) than those of the other groups (3.2 ± 3.1, 3.2 ± 3, and 3.1 ± 3.5 for groups 1, 2, and 4

  5. Assembly, intracellular processing, and expression at the cell surface of the human alpha beta T cell receptor/CD3 complex. Function of the CD3-zeta chain

    DEFF Research Database (Denmark)

    Geisler, C; Kuhlmann, J; Rubin, B

    1989-01-01

    The TCR/CD3 complex is a multimeric protein complex composed of a minimum of seven transmembrane chains (TCR alpha beta-CD3 gamma delta epsilon zeta 2). Whereas earlier studies have demonstrated that both the TCR-alpha and -beta chains are required for the cell surface expression of the TCR/CD3 c...... to form the heptameric complex (TCR alpha beta-CD3 gamma delta epsilon----TCR alpha beta-CD3 gamma delta epsilon 2); and 5) CD3-zeta is required for the export of the TCR/CD3 complex from the endoplasmic reticulum to the Golgi apparatus for subsequent processing....

  6. Supramolecular inclusion complexes between a coumarin dye and β-cyclodextrin, and attachment kinetics of thiolated β-cyclodextrin to gold surface

    Science.gov (United States)

    Velic, Dusan; Knapp, Martin; Köhler, Gottfried

    2001-10-01

    Supramolecular host-guest complexes formed between dye molecules, which are absorbing and fluorescing in the visible range, and cyclodextrin molecules are studied with the aim to generate a self-assembled nanostructured layer on a surface. Studies in solution show that an aminocoumarin dye, i.e. coumarin-6, binds strongly to β-cyclodextrin and yields fluorescent structures. The complex formation is substantiated by 17 nm blue shift of the fluorescence spectrum. The binding of thiolated cyclodextrin, 6-monodeoxy-6-monothio-β-cyclodextrin, to gold surface is then studied by induced change in the second-harmonic signal intensity generated from the surface. The saturation times of surface adsorption, as a measure of binding kinetics, are estimated for thiolated cyclodextrin as well as hexadecanethiol. The results support formation of self-assembled layers of the host molecules, which can serve as basis for the formation of supramolecular host-guest surface layers.

  7. Structure and function of airway surface layer of the human lungs & mobility of probe particles in complex fluids

    Science.gov (United States)

    Cai, Liheng

    Numerous infectious particles such as bacteria and pathogens are deposited on the airway surface of the human lungs during our daily breathing. To avoid infection the lung has evolved to develop a smart and powerful defense system called mucociliary clearance. The airway surface layer is a critical component of this mucus clearance system, which consists of two parts: (1) a mucus layer, that traps inhaled particles and transports them out of the lung by cilia-generated flow; and (2) a periciliary layer, that provides a favorable environment for ciliary beating and cell surface lubrication. For 75 years, it has been dogma that a single gel-like mucus layer, which is composed of secreted mucin glycoproteins, is transported over a "watery" periciliary layer. This one-gel model, however, does not explain fundamental features of the normal system, e.g. formation of a distinct mucus layer, nor accurately predict how the mucus clearance system fails in disease. In the first part of this thesis we propose a novel "Gel-on-Brush" model with a mucus layer (the "gel") and a "brush-like" periciliary layer, composed of mucins tethered to the luminal of airway surface, and supporting data accurately describes both the biophysical and cell biological bases for normal mucus clearance and its failure in disease. Our "Gel-on-Brush" model describes for the first time how and why mucus is efficiently cleared in health and unifies the pathogenesis of major human diseases, including cystic fibrosis and chronic obstructive pulmonary disease. It is expected that this "Gel-on-Brush" model of airway surface layer opens new directions for treatments of airway diseases. A dilemma regarding the function of mucus is that, although mucus traps any inhaled harmful particulates, it also poses a long-time problem for drug delivery: mobility of cargos carrying pharmaceutical agents is slowed down in mucus. The second part of this thesis aims to answer the question: can we theoretically understand the

  8. PALADYN v1.0, a comprehensive land surface-vegetation-carbon cycle model of intermediate complexity

    Science.gov (United States)

    Willeit, Matteo; Ganopolski, Andrey

    2016-10-01

    PALADYN is presented; it is a new comprehensive and computationally efficient land surface-vegetation-carbon cycle model designed to be used in Earth system models of intermediate complexity for long-term simulations and paleoclimate studies. The model treats in a consistent manner the interaction between atmosphere, terrestrial vegetation and soil through the fluxes of energy, water and carbon. Energy, water and carbon are conserved. PALADYN explicitly treats permafrost, both in physical processes and as an important carbon pool. It distinguishes nine surface types: five different vegetation types, bare soil, land ice, lake and ocean shelf. Including the ocean shelf allows the treatment of continuous changes in sea level and shelf area associated with glacial cycles. Over each surface type, the model solves the surface energy balance and computes the fluxes of sensible, latent and ground heat and upward shortwave and longwave radiation. The model includes a single snow layer. Vegetation and bare soil share a single soil column. The soil is vertically discretized into five layers where prognostic equations for temperature, water and carbon are consistently solved. Phase changes of water in the soil are explicitly considered. A surface hydrology module computes precipitation interception by vegetation, surface runoff and soil infiltration. The soil water equation is based on Darcy's law. Given soil water content, the wetland fraction is computed based on a topographic index. The temperature profile is also computed in the upper part of ice sheets and in the ocean shelf soil. Photosynthesis is computed using a light use efficiency model. Carbon assimilation by vegetation is coupled to the transpiration of water through stomatal conductance. PALADYN includes a dynamic vegetation module with five plant functional types competing for the grid cell share with their respective net primary productivity. PALADYN distinguishes between mineral soil carbon, peat carbon, buried

  9. Structures and Properties of As(OH)3 Adsorption Complexes on Hydrated Mackinawite (FeS) Surfaces: A DFT-D2 Study.

    Science.gov (United States)

    Dzade, Nelson Y; Roldan, Alberto; de Leeuw, Nora H

    2017-03-21

    Reactive mineral-water interfaces exert control on the bioavailability of contaminant arsenic species in natural aqueous systems. However, the ability to accurately predict As surface complexation is limited by the lack of molecular-level understanding of As-water-mineral interactions. In the present study, we report the structures and properties of the adsorption complexes of arsenous acid (As(OH)3) on hydrated mackinawite (FeS) surfaces, obtained from density functional theory (DFT) calculations. The fundamental aspects of the adsorption, including the registries of the adsorption complexes, adsorption energies, and structural parameters are presented. The FeS surfaces are shown to be stabilized by hydration, as is perhaps to be expected because the adsorbed water molecules stabilize the low-coordinated surface atoms. As(OH)3 adsorbs weakly at the water-FeS(001) interface through a network of hydrogen-bonded interactions with water molecules on the surface, with the lowest-energy structure calculated to be an As-up outer-sphere complex. Compared to the water-FeS(001) interface, stronger adsorption was calculated for As(OH)3 on the water-FeS(011) and water-FeS(111) interfaces, characterized by strong hybridization between the S-p and O-p states of As(OH)3 and the surface Fe-d states. The As(OH)3 molecule displayed a variety of chemisorption geometries on the water-FeS(011) and water-FeS(111) interfaces, where the most stable configuration at the water-FeS(011) interface is a bidentate Fe-AsO-Fe complex, but on the water-FeS(111) interface, a monodentate Fe-O-Fe complex was found. Detailed information regarding the adsorption mechanisms has been obtained via projected density of states (PDOS) and electron density difference iso-surface analyses and vibrational frequency assignments of the adsorbed As(OH)3 molecule.

  10. A photocatalytic reaction kinetics model based on electrical double layer theory(Ⅰ)--Surface complexation model at TiO2/water interface

    Institute of Scientific and Technical Information of China (English)

    李新军; 李芳柏; 何明兴; 王良焱; 徐悦华; 黄琮

    2002-01-01

    The kinetics of photocatalysis can be us ually described by Langmiur-H inshelwood adsorption expression. The adsorption can be greatly influenced by the surface properties of photocatalyst. Triple layer model (TLM) was chosen to describe the surface adsorption of TiO2 based on electrical double layer (EDL) theory at the TiO2/water interface. And through the potentiometrictit ration the parameters of TLM were determined by the extrapolation method and Fit eql3.1 software. The results show that surface complexation dominates the surfac e charge and the numerical calculation fits the experiment data satisfactorily.

  11. In-Situ ATR-FTIR and Surface Complexation Modeling Study of the Adsorption of Dimethylarsenic Acid and p-Arsanilic Acid on Iron Oxides

    Science.gov (United States)

    Goldberg, S. R.; Al-Abadleh, H.; Mitchell, W.

    2010-12-01

    Arsenic is an element that exists naturally in many rocks and minerals around the world, accumulates in petroleum, shale, and coal deposits as a result of biogeochemical processes, and is found in fly ash from fuel combustion. Arsenic compounds in their organic and inorganic forms pose both health and environmental risks. The environmental fate of arsenic compounds is controlled to a large extent by their surface interactions with inorganic and organic surfaces. We report results from applying the triple layer surface complexation model to adsorption isotherm and pH-envelope experimental data of dimethylarsenic acid, DMA, and p-arsanilic acid, p-AsA on the iron oxides, hematite and goethite. Ligand exchange reactions were based on the interpretation of ATR-FTIR spectra of DMA and p-AsA surface complexes. Surface coverage of the organoarsenicals was quantified in-situ from the spectral component at 840 cm-1. The best model fit to the DMA adsorption data was obtained using an outer-sphere complex, whereas for p-AsA, best model fit was obtained using two monodentate inner-sphere surface complexes. The significance of the results is discussed in relation to improving modeling tools used by environmental regulators. Accurate predictive modeling tools are needed for effective design of arsenic removal technologies using iron oxide minerals.

  12. Grain-Size Based Additivity Models for Scaling Multi-rate Uranyl Surface Complexation in Subsurface Sediments

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaoying; Liu, Chongxuan; Hu, Bill X.; Hu, Qinhong

    2016-07-01

    This study statistically analyzed a grain-size based additivity model that has been proposed to scale reaction rates and parameters from laboratory to field. The additivity model assumed that reaction properties in a sediment including surface area, reactive site concentration, reaction rate, and extent can be predicted from field-scale grain size distribution by linearly adding reaction properties for individual grain size fractions. This study focused on the statistical analysis of the additivity model with respect to reaction rate constants using multi-rate uranyl (U(VI)) surface complexation reactions in a contaminated sediment as an example. Experimental data of rate-limited U(VI) desorption in a stirred flow-cell reactor were used to estimate the statistical properties of multi-rate parameters for individual grain size fractions. The statistical properties of the rate constants for the individual grain size fractions were then used to analyze the statistical properties of the additivity model to predict rate-limited U(VI) desorption in the composite sediment, and to evaluate the relative importance of individual grain size fractions to the overall U(VI) desorption. The result indicated that the additivity model provided a good prediction of the U(VI) desorption in the composite sediment. However, the rate constants were not directly scalable using the additivity model, and U(VI) desorption in individual grain size fractions have to be simulated in order to apply the additivity model. An approximate additivity model for directly scaling rate constants was subsequently proposed and evaluated. The result found that the approximate model provided a good prediction of the experimental results within statistical uncertainty. This study also found that a gravel size fraction (2-8mm), which is often ignored in modeling U(VI) sorption and desorption, is statistically significant to the U(VI) desorption in the sediment.

  13. Remarkable fluorescence enhancement versus complex formation of cationic porphyrins on the surface of ZnO nanoparticles

    KAUST Repository

    Aly, Shawkat Mohammede

    2014-06-12

    Fluorescence enhancement of organic fluorophores shows tremendous potential to improve image contrast in fluorescence-based bioimaging. Here, we present an experimental study of the interaction of two cationic porphyrins, meso-tetrakis(1-methylpyridinium-4-yl)porphyrin chloride (TMPyP) and meso-tetrakis(4-N,N,N-trimethylanilinium)porphyrin chloride (TMAP), with cationic surfactant-stabilized zinc oxide nanoparticles (ZnO NPs) based on several steady-state and time-resolved techniques. We show the first experimental measurements demonstrating a clear transition from pronounced fluorescence enhancement to charge transfer (CT) complex formation by simply changing the nature and location of the positive charge of the meso substituent of the cationic porphyrins. For TMPyP, we observe a sixfold increase in the fluorescence intensity of TMPyP upon addition of ZnO NPs. Our experimental results indicate that the electrostatic binding of TMPyP with the surface of ZnO NPs increases the symmetry of the porphyrin macrocycle. This electronic communication hinders the rotational relaxation of the meso unit and/or decreases the intramolecular CT character between the cavity and the meso substituent of the porphyrin, resulting in the enhancement of the intensity of the fluorescence. For TMAP, on the other hand, the different type and nature of the positive charge resulting in the development of the CT band arise from the interaction with the surface of ZnO NPs. This observation is confirmed by the femtosecond transient absorption spectroscopy, which provides clear spectroscopic signatures of photoinduced electron transfer from TMAP to ZnO NPs. © 2014 American Chemical Society.

  14. In situ ATR-FTIR and surface complexation modeling studies on the adsorption of dimethylarsinic acid and p-arsanilic acid on iron-(oxyhydr)oxides.

    Science.gov (United States)

    Mitchell, William; Goldberg, Sabine; Al-Abadleh, Hind A

    2011-06-15

    Arsenic is an element that exists naturally in many rocks and minerals around the world. It also accumulates in petroleum, shale, oil sands, and coal deposits as a result of biogeochemical processes, and it has been found in fly ash from the combustion of solid biofuels. Arsenic compounds in their organic and inorganic forms pose both a health and an environmental risk, and continue to be a challenge to the energy industry. The environmental fate and removal technologies of arsenic compounds are controlled to a large extent by their surface interactions with inorganic and organic adsorbents. We report thermodynamic binding constants, K(binding), from applying the triple-layer surface complexation model to adsorption isotherm and pH envelope data for dimethylarsinic acid (DMA) and p-arsanilic acid (p-AsA) on hematite and goethite. Ligand exchange reactions were constructed based on the interpretation of ATR-FTIR spectra of DMA and p-AsA surface complexes. Surface coverage of adsorbates was quantified in situ from the spectral component at 840 cm(-1). The best fit to the DMA adsorption data was obtained using outer-sphere complex formation, whereas for p-AsA, the best fit was obtained using two monodentate inner-sphere surface complexes. The significance of the results is discussed in relation to improving modeling tools used by environmental regulators and the energy sector for optimum control of arsenic content in fuels.

  15. Shallow sub-surface structure of the central volcanic complex of Tenerife, Canary Islands: implications for the evolution and the recent reactivation of the Las Canadas caldera

    Energy Technology Data Exchange (ETDEWEB)

    Gottsmann, J [Department of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ (United Kingdom); Camacho, A G; Fernandez, J [Instituto de Astronomia y Geodesia (CSIC-UCM), Ciudad Universitaria, Pza. de Ciencias, 3, 28040 Madrid (Spain); MartI, J [Institute of Earth Sciences ' Jaume Almera' , CSIC, Lluis Sole SabarIs s/n, Barcelona 08028 (Spain); Wooller, L; Rymer, H [Department of Earth and Environmental Sciences, Open University, Walton Hall, Milton Keynes, MK7 6AA (United Kingdom); GarcIa, A [Department of Volcanology, Museo Nacional de Ciencias Naturales, CSIC, C/ Jose Gutierrez Abascal, 2, 28006 Madrid (Spain)], E-mail: j.gottsmann@bristol.ac.uk

    2008-10-01

    We present a new local Bouguer anomaly map of the Central Volcanic Complex (CVC) of Tenerife, Spain. The high-density core of the CVC and the pronounced gravity low centred in the Las Canadas caldera (LCC) in greater detail than previously available. Mathematical construction of a subsurface model from the local anomaly data, employing a 3-D inversion enables mapping of the shallow structure beneath the complex, giving unprecedented insights into the sub-surface architecture of the complex, and shedding light on its evolution.

  16. Evidence for the formation of an intermediate complex in the direct metalation of tetra(4-bromophenyl)-porphyrin on the Cu(111) surface

    OpenAIRE

    SENGE, Mathias

    2011-01-01

    PUBLISHED A strong molecule?surface interaction between free-base-tetra- (4-bromophenyl)-porphyrin and Cu(111) results in a distortion of both the molecule and the underlying copper surface in the vicinity of the molecule. This in turn leads to the formation of an intermediate complex due to bonding between the iminic nitrogens and surface copper atoms. This work was supported by Science Foundation Ireland, through grant numbers 08/RFP/PHY1366 to AAC and 09/IN.1/B26...

  17. Inner-sphere complexation of cations at the rutile-water interface: A concise surface structural interpretation with the CD and MUSIC model

    Science.gov (United States)

    Ridley, Moira K.; Hiemstra, Tjisse; van Riemsdijk, Willem H.; Machesky, Michael L.

    2009-04-01

    Acid-base reactivity and ion-interaction between mineral surfaces and aqueous solutions is most frequently investigated at the macroscopic scale as a function of pH. Experimental data are then rationalized by a variety of surface complexation models. These models are thermodynamically based which in principle does not require a molecular picture. The models are typically calibrated to relatively simple solid-electrolyte solution pairs and may provide poor descriptions of complex multi-component mineral-aqueous solutions, including those found in natural environments. Surface complexation models may be improved by incorporating molecular-scale surface structural information to constrain the modeling efforts. Here, we apply a concise, molecularly-constrained surface complexation model to a diverse suite of surface titration data for rutile and thereby begin to address the complexity of multi-component systems. Primary surface charging curves in NaCl, KCl, and RbCl electrolyte media were fit simultaneously using a charge distribution (CD) and multisite complexation (MUSIC) model [Hiemstra T. and Van Riemsdijk W. H. (1996) A surface structural approach to ion adsorption: the charge distribution (CD) model. J. Colloid Interf. Sci. 179, 488-508], coupled with a Basic Stern layer description of the electric double layer. In addition, data for the specific interaction of Ca 2+ and Sr 2+ with rutile, in NaCl and RbCl media, were modeled. In recent developments, spectroscopy, quantum calculations, and molecular simulations have shown that electrolyte and divalent cations are principally adsorbed in various inner-sphere configurations on the rutile 1 1 0 surface [Zhang Z., Fenter P., Cheng L., Sturchio N. C., Bedzyk M. J., Předota M., Bandura A., Kubicki J., Lvov S. N., Cummings P. T., Chialvo A. A., Ridley M. K., Bénézeth P., Anovitz L., Palmer D. A., Machesky M. L. and Wesolowski D. J. (2004) Ion adsorption at the rutile-water interface: linking molecular and macroscopic

  18. inner-sphere complexation of cations at the rutile-water interface: A concise surface structural interpretation with the CD and MUSIC model

    Energy Technology Data Exchange (ETDEWEB)

    Ridley, Mora K. [Texas Tech University, Lubbock; Hiemstra, T [Oak Ridge National Laboratory (ORNL); Van Riemsdijk, Willem H. [Wageningen University and Research Centre, The Netherlands; Machesky, Michael L. [Illinois State Water Survey, Champaign, IL

    2009-01-01

    Acid base reactivity and ion-interaction between mineral surfaces and aqueous solutions is most frequently investigated at the macroscopic scale as a function of pH. Experimental data are then rationalized by a variety of surface complexation models. These models are thermodynamically based which in principle does not require a molecular picture. The models are typically calibrated to relatively simple solid-electrolyte solution pairs and may provide poor descriptions of complex multicomponent mineral aqueous solutions, including those found in natural environments. Surface complexation models may be improved by incorporating molecular-scale surface structural information to constrain the modeling efforts. Here, we apply a concise, molecularly-constrained surface complexation model to a diverse suite of surface titration data for rutile and thereby begin to address the complexity of multi-component systems. Primary surface charging curves in NaCl, KCl, and RbCl electrolyte media were fit simultaneously using a charge distribution (CD) and multisite complexation (MUSIC) model [Hiemstra T. and Van Riemsdijk W. H. (1996) A surface structural approach to ion adsorption: the charge distribution (CD) model. J. Colloid Interf. Sci. 179, 488 508], coupled with a Basic Stern layer description of the electric double layer. In addition, data for the specific interaction of Ca2+ and Sr2+ with rutile, in NaCl and RbCl media, were modeled. In recent developments, spectroscopy, quantum calculations, and molecular simulations have shown that electrolyte and divalent cations are principally adsorbed in various inner-sphere configurations on the rutile 110 surface [Zhang Z., Fenter P., Cheng L., Sturchio N. C., Bedzyk M. J., Pr edota M., Bandura A., Kubicki J., Lvov S. N., Cummings P. T., Chialvo A. A., Ridley M. K., Be ne zeth P., Anovitz L., Palmer D. A., Machesky M. L. and Wesolowski D. J. (2004) Ion adsorption at the rutile water interface: linking molecular and macroscopic

  19. Direct visualization of peptide/MHC complexes at the surface and in the intracellular compartments of cells infected in vivo by Leishmania major.

    Directory of Open Access Journals (Sweden)

    Eric Muraille

    Full Text Available Protozoa and bacteria infect various types of phagocytic cells including macrophages, monocytes, dendritic cells and eosinophils. However, it is not clear which of these cells process and present microbial antigens in vivo and in which cellular compartments parasite peptides are loaded onto Major Histocompatibility Complex molecules. To address these issues, we have infected susceptible BALB/c (H-2d mice with a recombinant Leishmania major parasite expressing a fluorescent tracer. To directly visualize the antigen presenting cells that present parasite-derived peptides to CD4+ T cells, we have generated a monoclonal antibody that reacts to an antigenic peptide derived from the parasite LACK antigen bound to I-Ad Major Histocompatibility Complex class II molecule. Immunogold electron microscopic analysis of in vivo infected cells showed that intracellular I-Ad/LACK complexes were present in the membrane of amastigote-containing phagosomes in dendritic cells, eosinophils and macrophages/monocytes. In both dendritic cells and macrophages, these complexes were also present in smaller vesicles that did not contain amastigote. The presence of I-Ad/LACK complexes at the surface of dendritic cells, but neither on the plasma membrane of macrophages nor eosinophils was independently confirmed by flow cytometry and by incubating sorted phagocytes with highly sensitive LACK-specific hybridomas. Altogether, our results suggest that peptides derived from Leishmania proteins are loaded onto Major Histocompatibility Complex class II molecules in the phagosomes of infected phagocytes. Although these complexes are transported to the cell surface in dendritic cells, therefore allowing the stimulation of parasite-specific CD4+ T cells, this does not occur in other phagocytic cells. To our knowledge, this is the first study in which Major Histocompatibility Complex class II molecules bound to peptides derived from a parasite protein have been visualized within and

  20. Method of calculation and construction of arrangement sketchy of stone-working machine for the processing of geometrically-complex surfaces of wares of large gabarit

    OpenAIRE

    Чемоданов, Петро Арисович

    2016-01-01

    In the article the method of calculation of basic knots and arrangement sketchy of stone-working gantry milling mapping machine is offered with curvilinear working motion of light cart for the processing of geometrically-complex surfaces on the stoning purveyance of large gabarit.

  1. Reduction of protein adsorption on silica and polysulfone surfaces coated with complex coacervate core micelles with poly(vinyl alcohol) as a neutral brush forming block

    NARCIS (Netherlands)

    Brzozowska, A. M.; Zhang, Q.; de Keizer, A.; Norde, W.; Stuart, M. A. Cohen

    2010-01-01

    We have studied the formation and stability of complex coacervate core micelles (C3Ms) in solution, and the influence of C3M coatings on the adsorption of the proteins beta-lactoglobulin (beta-lac), bovine serum albumin (BSA). and lysozyme (Lsz) on silica and polysulfone surfaces. The C3M5 consist o

  2. Refined ab initio intermolecular ground-state potential energy surface for the He-C2H2 van der Waals complex

    DEFF Research Database (Denmark)

    Fernández, Berta; Henriksen, Christian; Farrelly, David

    2013-01-01

    , are fitted to a 15-parameter analytic function. The potential is characterised by minima of-24.21 cm-1 at distances between the rare gas atom and the C2H2 centre of mass of 4.3453 Å, and with the complex in a linear configuration. At intermediate distances the surface is rather similar to that developed...

  3. A new route for visible/near-infrared-light-driven H2 production over titania: Co-sensitization of surface charge transfer complex and zinc phthalocyanine

    Science.gov (United States)

    Zhang, Xiaohu; Peng, Bosi; Peng, Tianyou; Yu, Lijuan; Li, Renjie; Zhang, Jing

    2015-12-01

    This work introduces a new strategy for visible/near-infrared (NIR) light responsive H2 production over TiO2 nanoparticles co-sensitized with zinc phthalocyanine derivative (Zn-tri-PcNc) and surface ligand-to-metal charge transfer (LMCT) complex, which is in situ formed on the TiO2 nanoparticles' surfaces by using ascorbic acid (AA). The in situ formed surface LMCT complex (AA-TiO2) exhibits obvious visible-light-responsive photoactivity (126.2 μmol/h) for H2 production with a high apparent quantum yield (AQY) of 16.1% at 420 nm monochromatic light irradiation. Moreover, the co-sensitized TiO2 nanoparticles (Zn-tri-PcNc-TiO2-AA) shows a much higher photoactivity (162.2 μmol/h) for H2 production than the surface LMCT complex, and broader spectral responsive region (400-800 nm) with a relatively high AQY value (0.97%) at 700 nm monochromatic light irradiation. The present result reveals a possible substitute for the conventional Ru(II)-bipyridyl complexes or organic dyes as sensitizer of semiconductors in the field of solar fuel conversion.

  4. Non-destructive testing of objects of complex shape using infrared thermography: rear surface reconstruction by temporal tracking of the thermal front

    Science.gov (United States)

    Djupkep Dizeu, F. B.; Laurendeau, Denis; Bendada, Abdelhakim

    2016-12-01

    Infrared thermography allows contactless non-destructive testing of objects based on their thermal behavior. Quantitative inspection of an object aims to characterize its internal defects by estimating their size and their depth. In the field, a one-dimensional thermal model has been used for depth estimation. Unfortunately, the methods based on this model become inaccurate when the inspected object has a high thermal diffusivity, a complex shape, or when the defects, like corrosion, have a complex geometry. For such cases, a 3D formulation of the problem is needed. In this paper, we consider the defect characterization as an inverse geometry problem and we propose a new method: the rear surface reconstruction by temporal tracking of the thermal front. The idea is to follow the thermal front while it propagates inside the object. Referring to the duality time-depth, at every moment, the penetration depth of the thermal front can be estimated. As soon as the thermal front reaches the rear surface, a temperature change will be noticeable on the frontal surface. It is then possible to update the internal geometry of the object at each time step in such a way that the difference between the theoretical temperature, obtained by a 3D solver, and the experimental temperature, recorded by an infrared camera, is minimized. The proposed method shows accurate results and can address situations involving rear surfaces with complex geometry and objects with high thermal diffusivity and a complex shape.

  5. Synthesis of novel lanthanide acylpyrazolonato ligands with long aliphatic chains and immobilization of the Tb complex on the surface of silica pre-modified via hydrophobic interactions.

    Science.gov (United States)

    Pettinari, C; Marchetti, F; Pettinari, R; Belousov, Y A; Taydakov, I V; Krasnobrov, V D; Petukhov, D I; Drozdov, A A

    2015-09-01

    Five new complexes Ln(Q(C17))3(H2O)(Solv) (Ln = Y, Solv = H2O, Ln = Tb, Dy, Sm or Eu, Solv = EtOH) were synthesized with the acylpyrazolonato ligand Q(C17) bearing a long aliphatic C17H35 chain in the acyl moiety, and the crystal structure of Y(Q(C17))3(H2O)2 shows the three aliphatic chains from the coordinated ligands positioned in the same direction, affording plane layers built by Y(Q(C17))3(H2O)2 molecules connected through H-bonding interactions. The layers are stitched to each other like in "hook & loop" tapes. Luminescence of complexes was determined and the complex Tb(Q(C17))3(H2O)(EtOH) was immobilized on the surface of silica preprocessed using a C17H35CONH(CH2)3Si(OEt)3 reagent via hydrophobic interactions of long aliphatic chains. Luminescent properties and micromorphology of the obtained hybrid particles and hybrid films were investigated. Intensive green emission of the complex retains after grafting onto the silica surface. Inclusion of the complex on the surface of silica materials occurs as separate molecules, after the disruption of the H-bonding network present in the crystalline phase of the pure terbium sample.

  6. Equilibration of complexes of DNA and H-NS proteins on charged surfaces: A coarse-grained model point of view

    CERN Document Server

    Joyeux, Marc

    2014-01-01

    The Histone-like Nucleoid Structuring protein (H-NS) is a nucleoid-associated protein, which is involved in both gene regulation and DNA compaction. Although it is a key player in genome organization by forming bridges between DNA duplexes, the precise structure of complexes of DNA and H-NS proteins is still not well understood. In particular, it is not clear whether the structure of DNA/H-NS complexes in the living cell is similar to that of complexes deposited on mica surfaces, which may be observed by AFM microscopy. A coarse-grained model, which helps getting more insight into this question, is described and analyzed in the present paper. This model is able of describing both the bridging of bacterial DNA by H-NS in the bulk and the deposition and equilibration of the complex on a charged surface. Simulations performed with the model reveal that a slight attraction between DNA and the charged surface is sufficient to let DNA/H-NS complexes reorganize from 3D coils to planar plasmids bridged by H-NS protei...

  7. Crystal structures, DFT calculations and Hirshfeld surface analyses of three new cobalt(III) Schiff base complexes derived from meso-1,2-diphenyl-1,2-ethylenediamine

    Science.gov (United States)

    Masoudi, Mohaddeseh; Behzad, Mahdi; Arab, Ali; Tarahhomi, Atekeh; Rudbari, Hadi Amiri; Bruno, Giuseppe

    2016-10-01

    Three new Cobalt(III) Schiff base complexes were synthesized and characterized by spectroscopic methods and x-ray crystallography. The DFT optimized structures of the complexes agreed well with the corresponding x-ray structures. According to the calculated vibrational normal modes, the observed signals in the IR spectra of the complexes were assigned. The experimental UV-Vis spectra of the complexes were also discussed considering the calculated excited states and molecular orbitals. Hirshfeld surface analysis was carried out to study the inter-contact interactions in these complexes. These studies provided comprehensive description of such inter-contact interactions by means of an appealing graphical approach using 3D Hirshfeld surfaces and 2D fingerprint plots derived from the surfaces. It indicated the dominant role of various hydrogen intermolecular interactions such as H⋯H (above 60%), C⋯H/H⋯C (near 15%-20%), O⋯H/H⋯O (about 16% or 17% for structures with counter ion ClO4-) and H⋯F (17% for structure with counter ion PF6-) contacts into the crystal packing which are discussed in details.

  8. Analysis of regional gullies within Noachis Terra, Mars: A complex relationship between slope, surface material and aspect

    Science.gov (United States)

    Hobbs, S. W.; Paull, D. J.; Clarke, J. D. A.

    2015-04-01

    The precise mechanisms by which martian hillside gullies erode and their dependence on the local environment remain subjects of debate. We studied three sharp rimmed craters in Noachis Terra and 37 gully profiles using Context Camera (CTX), Mars Orbiter Laser Altimeter (MOLA) and High Resolution Stereo Camera (HRSC) data. We analysed the gully topographic profiles of seven gullies and nine dry ravines. We measured slope properties using HRSC elevation data and used thermal inertia to infer material types of the gully sites. We compared these with three nearby Noachian age craters possessing crater wall slope angles within the range of previously observed gully formations. In-line with previous findings on individual gullies, we found that the slope angles of gullies in our study area consistently reflect the inherited slope angles of the host escarpment, suggesting that traditional slope-based evidence of fluvial activity in martian gullies needs to be placed in context of its local environment. We also observed a direct relationship between gully morphology and local composition of surface units. Martian gully features, and possibly method of erosion appeared heavily influenced by changes in underlying geology and presence of erodible sediment. Examples included gully shape changing in accordance with type of erodible sediment. We suggest that the degraded rims of gully-free Noachian craters precluded slope angles high enough to trigger creation of precursors to alcoves through mass wasting. Lack of these hollows has probably prevented the accumulation of enough ice-rich sediment for gullies to form in. Our analysis reveals that there is a complex interdependence between slope processes and the local environment, and global martian gully models may not work at the local scale.

  9. Covalent co-immobilization of heparin/laminin complex that with different concentration ratio on titanium surface for selectively direction of platelets and vascular cells behavior

    Science.gov (United States)

    Wang, Jian; Chen, Yuan; Liu, Tao; Wang, Xue; Liu, Yang; Wang, Yuan; Chen, Junying; Huang, Nan

    2014-10-01

    Surface biofunctional modification of coronary artery stent to improve the hemocompatibility and selectively accelerate endothelium regeneration but prevent restenosis have been become a new hotspot. For this, a novel method was developed in this work by co-immobilization of Ln and heparin complex on poly-L-lysine modified Ti surface. Take the advantage of the specific interaction between Ln and heparin, Ln and heparin complexes with different concentration ratios were set up for creating different exposure density of these two types of biomolecules. According to biocompatibility evaluation results, the Hep/Ln complexes modified surface displayed less platelet adhesion and activation. Especially, on L(150)H and L(200)H surface, the AT III binding quantity, APTT value and anti-coagulation property of modified surface were significantly promoted. Furthermore, the adherent density and proliferation activity of ECs and EPCs were positively correlated with Ln concentration. Notably, the proliferation of both ECs and EPCs on L(100)H, L(150)H and L(200)H surface were greatly promoted. Another hand, the proliferation activity of SMCs was significantly inhibited on Hep/Ln modified surfaces, which was considered mainly due to the inhibitory effect of heparin to SMCs. According to the existing results, this study demonstrated that in a certain range of heparin and laminin concentration ratio, the biological behavior of platelets, ECs, EPCs and SMCs could be selectively directed. We suggested that this article provided a potential method to construct an adequate platform on a stent surface for accelerate endothelialization with low side effects.

  10. Unusual Complex Formation and Chemical Reaction of Haloacetate Anion on the Exterior Surface of Cucurbit[6]uril in the Gas Phase

    Science.gov (United States)

    Choi, Tae Su; Ko, Jae Yoon; Heo, Sung Woo; Ko, Young Ho; Kim, Kimoon; Kim, Hugh I.

    2012-10-01

    Noncovalent interactions of cucurbit[6]uril (CB[6]) with haloacetate and halide anions are investigated in the gas phase using electrospray ionization ion mobility mass spectrometry. Strong noncovalent interactions of monoiodoacetate, monobromoacetate, monochloroacetate, dichloroacetate, and trichloroacetate on the exterior surface of CB[6] are observed in the negative mode electrospray ionization mass spectra. The strong binding energy of the complex allows intramolecular SN2 reaction of haloacetate, which yields externally bound CB[6]-halide complex, by collisional activation. Utilizing ion mobility technique, structures of exteriorly bound CB[6] complexes of haloacetate and halide anions are confirmed. Theoretically determined low energy structures using density functional theory (DFT) further support results from ion mobility studies. The DFT calculation reveals that the binding energy and conformation of haloacetate on the CB[6] surface affect the efficiency of the intramolecular SN2 reaction of haloacetate, which correlate well with the experimental observation.

  11. An ab initio study of the adsorption of Eu3+, Pu3+, Am3+, and Cm3+ hydroxide complexes on hematite (001) surface: Role of magnetism on adsorption

    Science.gov (United States)

    Yuan, Ke; Taylor, Sandra D.; Powell, Brian A.; Becker, Udo

    2017-10-01

    Inner-sphere hydroxide complexes of Eu3+, Pu3+, Am3+, and Cm3+ adsorbed to antiferromagnetic and ferromagnetic hematite (001) surfaces were modeled by using DFT (GGA + U) calculations in order to compare the electronic properties, atomic structures, and adsorption energies between the trivalent actinide analog Eu3+ and the corresponding actinides An3+. Eu3+ forms a tridentate-binuclear surface complex on the hematite surface with an Eu-Fe distance of 3.4-3.8 Å. Eu3+ is partially reduced upon adsorption, as indicated by the increase of original Eu3+ spin value from 6 to ∼7. Eu3+ adsorption on the ferromagnetic surface is energetically more favorable than on the antiferromagnetic surface, while the opposite is the case for all actinides An3+. When retaining a similar adsorption configuration (e.g., coordination number = 6), An3+ cations are adsorbed ∼0.2 Å closer to the surface compared to Eu3+. Partial density of states analyses indicate ionic bonding between O ions on the hematite surface and the Eu3+/An3+ adsorbates. An increasing number of bands above the Fermi energy were found when Eu3+ and An3+ were adsorbed to the ferromagnetic surface but not on the antiferromagnetic surface, indicating the ferromagnetic substrate becomes more semiconducting upon cation adsorption. These results show that the spin configurations of the hematite (001) surface have a weak but distinct influence on the cation adsorption energy. Although the antiferromagnetic spin configuration of hematite is dominant in nature, metastable ferromagnetic domains on nanohematite grains may influence the energetics of certain cation adsorption reactions.

  12. SURVEY, REPRESENTATION AND ANALYSIS OF A WAR I COMPLEX SYSTEM OF SURFACE AND UNDERGROUND FORTIFICATIONS IN THE GRESTA VALLEY, ITALY

    Directory of Open Access Journals (Sweden)

    I. Salvador

    2012-09-01

    Full Text Available This work is part of a research on the use of terrestrial laser scanner, integrated with total station and GPS, for the documentation and comprehension of complex architectures in up-land sites. The research is performed in the framework of the project "Ambiente e Paesaggi dei siti di Altura Trentini" – APSAT (Environment and landscape of hill-top sites in Trentino, a multidisciplinary project focused on the evolution of hill-top anthropic system in the Trentino region, Italy. The study area is located in the Gresta Valley and this work concerns on the Nagià Grom site, fortified by the Austria-Hungarian Army during the World War I. The site has been interested by a significant restore operation of a large series of entrenches paths and fortifications in the last decade. The survey herein described has involved an area once interested by military barracks with Officers' Mess, water provision and by one of the biggest field kitchens discovered in the Trentino region. A second survey involved the tunnel connecting the ammunition depot to the artillery stations. The nature of such complex architectures, characterized by an irregular and composite 3D span leads, in general, to necessary simple surveys and representations and somehow to simplified studies too. The 3D point cloud, once filtered by the massive presence of dense vegetation, eventually constitutes a rich data set for further analyses on the spatial, geological, architectural and historical properties of the site. The analysis has been carried out on two different scales. At the architectural-scale, the comparison to historic photos has allowed to understand how the original structure of the barracks was made and to find building characters that now are lost. The on-site observation of the underground stratigraphic splices and their analysis in the 3D point cloud, e.g., spatial extension and slope, have permitted the understanding of the special excavation process guided by the

  13. Survey, Representation and Analysis of a War i Complex System of Surface and Underground Fortifications in the Gresta Valley, Italy

    Science.gov (United States)

    Salvador, I.; Vitti, A.

    2011-09-01

    This work is part of a research on the use of terrestrial laser scanner, integrated with total station and GPS, for the documentation and comprehension of complex architectures in up-land sites. The research is performed in the framework of the project "Ambiente e Paesaggi dei siti di Altura Trentini" - APSAT (Environment and landscape of hill-top sites in Trentino), a multidisciplinary project focused on the evolution of hill-top anthropic system in the Trentino region, Italy. The study area is located in the Gresta Valley and this work concerns on the Nagià Grom site, fortified by the Austria-Hungarian Army during the World War I. The site has been interested by a significant restore operation of a large series of entrenches paths and fortifications in the last decade. The survey herein described has involved an area once interested by military barracks with Officers' Mess, water provision and by one of the biggest field kitchens discovered in the Trentino region. A second survey involved the tunnel connecting the ammunition depot to the artillery stations. The nature of such complex architectures, characterized by an irregular and composite 3D span leads, in general, to necessary simple surveys and representations and somehow to simplified studies too. The 3D point cloud, once filtered by the massive presence of dense vegetation, eventually constitutes a rich data set for further analyses on the spatial, geological, architectural and historical properties of the site. The analysis has been carried out on two different scales. At the architectural-scale, the comparison to historic photos has allowed to understand how the original structure of the barracks was made and to find building characters that now are lost. The on-site observation of the underground stratigraphic splices and their analysis in the 3D point cloud, e.g., spatial extension and slope, have permitted the understanding of the special excavation process guided by the practical advantage of

  14. New Ru(II)/Os(II)-polypyridyl complexes for coupling to TiO2 surfaces through acetylacetone functionality and studies on interfacial electron-transfer dynamics.

    Science.gov (United States)

    Banerjee, Tanmay; Biswas, Abul Kalam; Sahu, Tuhin Subhra; Ganguly, Bishwajit; Das, Amitava; Ghosh, Hirendra Nath

    2014-09-28

    New Ru(ii)- and Os(ii)-polypyridyl complexes have been synthesized with pendant acetylacetone (acac) functionality for anchoring on nanoparticulate TiO2 surfaces with a goal of developing an alternate sensitizer that could be utilized for designing an efficient dye-sensitized solar cell (DSSC). Time-resolved transient absorption spectroscopic studies in the femtosecond time domain have been carried out. The charge recombination rates are observed to be very slow, compared with those for strongly coupled dye molecules having catechol as the anchoring functionality. The results of such studies reveal that electron-injection rates from the metal complex-based LUMO to the conduction band of TiO2 are faster than one would expect for an analogous complex in which the chromophoric core and the anchoring moiety are separated with multiple saturated C-C linkages. Such an observation is rationalized based on computational studies, and a relatively smaller spatial distance between the dye LUMO and the TiO2 surface accounted for this. Results of this study are compared with those for analogous complexes having a gem-dicarboxy group as the anchoring functionality for covalent binding to the TiO2 surface to compare the role of binding functionalities on electron-transfer dynamics.

  15. Supramolecular architectures in luminescent Zn(II) and Cd(II) complexes containing imidazole derivatives: Crystal structures, vibrational and thermal properties, Hirshfeld surface analysis and electrostatic potentials

    Science.gov (United States)

    Di Santo, Alejandro; Echeverría, Gustavo A.; Piro, Oscar E.; Pérez, Hiram; Ben Altabef, Aida; Gil, Diego M.

    2017-04-01

    Three novel zinc and cadmium complexes with 1-methylimidazole and 2-methylimidazole as ligands, mono-nuclear dichloro-bis(1-methylimidazole) zinc(II) and dibromo-bis(2-methylimidazole)cadmium(II) monohydrate complexes, and poly-nuclear bis(1-methylimidazole)-di-(μ2-bromo)cadmium(II) complex, namely, compounds 1-3, respectively, have been synthesized. The complexes were characterized by IR and Raman spectroscopies, thermal analysis and fluorescence. All the compounds exhibit interesting luminescent properties in solid state originated from intra-ligand (π→π*) transitions. Crystal structures of 1-3 were determined by single-crystal X-ray diffraction. Compound 1 crystallizes in P21/n space group, the Zn(II) ion lies at a crystal general position in a tetrahedral environment, and the mono-nuclear units are weakly bonded to one another by Csbnd H⋯Cl hydrogen bonds. Compound 2 crystallizes in Pnma space group, and mirror-related tetrahedral units around Cd(II) ion are H-bonded through a water molecule. Compound 3 crystallizes in P21/c space group, and the Cd(II) ion presents a centrosymmetric octahedral coordination. Neighboring and equatorial edge-sharing octahedra conform a polymeric arrangement that extends along the crystal a-axis. Weak hydrogen bonds are the major driving forces in the crystal packing of the three complexes. Hirshfeld surface analysis reveals a detailed scrutiny of intermolecular interactions experienced by each complex. The surfaces mapped over dnorm property highlight the X···H (X = Cl, Br) as the main intermolecular contacts for the three complexes, being also relevant the presence of O⋯H contacts for complex 2. The surfaces mapped over Shape index and curvedness properties for the two Cd complexes allow identify π … π stacking interactions which are absent in the Zn complex. 2D fingerprint plots have been used to quantify the relative contribution of the intermolecular contacts to crystal stability of compounds, showing

  16. Sum frequency generation vibrational spectroscopy (SFG-VS) for complex molecular surfaces and interfaces: Spectral lineshape measurement and analysis plus some controversial issues

    Science.gov (United States)

    Wang, Hong-Fei

    2016-12-01

    Sum-frequency generation vibrational spectroscopy (SFG-VS) was first developed in the 1980s and it has been proven a uniquely sensitive and surface/interface selective spectroscopic probe for characterization of the structure, conformation and dynamics of molecular surfaces and interfaces. In recent years, there have been many progresses in the development of methodology and instrumentation in the SFG-VS toolbox that have significantly broadened the application to complex molecular surfaces and interfaces. In this review, after presenting a unified view on the theory and methodology focusing on the SFG-VS spectral lineshape, as well as the new opportunities in SFG-VS applications with such developments, some of the controversial issues that have been puzzling the community are discussed. The aim of this review is to present to the researchers and students interested in molecular surfaces and interfacial sciences up-to-date perspectives complementary to the existing textbooks and reviews on SFG-VS.

  17. Sum frequency generation vibrational spectroscopy (SFG-VS) for complex molecular surfaces and interfaces: Spectral lineshape measurement and analysis plus some controversial issues

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hong-Fei

    2016-12-01

    Sum-frequency generation vibrational spectroscopy (SFG-VS) was first developed in the 1980s and it has been proven a uniquely sensitive and surface/interface selective spectroscopic probe for characterization of the structure, conformation and dynamics of molecular surfaces and interfaces. In recent years, there has been significant progress in the development of methodology and instrumentation in the SFG-VS toolbox that has significantly broadened the application to complex molecular surfaces and interfaces. In this review, after presenting a unified view on the theory and methodology focusing on the SFG-VS spectral lineshape, as well as the new opportunities in SFG-VS applications with such developments, some of the controversial issues that have been puzzling the community are to be discussed. The aim of this review is to present to the researchers and students interested in molecular surfaces and interfacial sciences up-to-date perspectives complementary to the existing textbooks and reviews on SFG-VS.

  18. Covalently grafted, silica gel supported C-protected cysteine or cystine copper complexes - syntheses, structure and possible surface reactions studied by FT-IR spectroscopy

    Science.gov (United States)

    Aranyi, A.; Csendes, Z.; Kiss, J. T.; Pálinkó, I.

    2009-04-01

    In this work the covalent anchoring of C-protected Cu(II)- L-cysteine and Cu(II)- L-cystine complexes onto a surface-modified silica gel is described. Conditions of the syntheses were varied and the obtained structures were studied by classical analytical (titration) as well as spectroscopic (infrared, atomic absorption) methods. It was found that the sulphur atoms in the molecules acted as primary coordination sites, while the other coordinating groups varied depending on whether the complexes were formed under ligand-poor or ligand-excess conditions.

  19. Covalent co-immobilization of heparin/laminin complex that with different concentration ratio on titanium surface for selectively direction of platelets and vascular cells behavior

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jian; Chen, Yuan; Liu, Tao; Wang, Xue; Liu, Yang; Wang, Yuan; Chen, Junying, E-mail: chenjy@263.net; Huang, Nan

    2014-10-30

    Highlights: • Extracellular matrix inspired surface modification with fibronectin, heparin and VEGF to construct a favorable microenvironment for selectively anticoagulant and promote endothelialization. • Take the advantage of specific intermolecular interaction, the bioactivity of above biomolecules was more efficiently maintained in compared with the common used covalent immobilization method. • Poly-l-lysine was used as a novel interlayer for surface amination, and in comparison, PLL coating was more feasible and the degradation product had no harm to human body. - Abstract: Surface biofunctional modification of coronary artery stent to improve the hemocompatibility and selectively accelerate endothelium regeneration but prevent restenosis have been become a new hotspot. For this, a novel method was developed in this work by co-immobilization of Ln and heparin complex on poly-L-lysine modified Ti surface. Take the advantage of the specific interaction between Ln and heparin, Ln and heparin complexes with different concentration ratios were set up for creating different exposure density of these two types of biomolecules. According to biocompatibility evaluation results, the Hep/Ln complexes modified surface displayed less platelet adhesion and activation. Especially, on L(150)H and L(200)H surface, the AT III binding quantity, APTT value and anti-coagulation property of modified surface were significantly promoted. Furthermore, the adherent density and proliferation activity of ECs and EPCs were positively correlated with Ln concentration. Notably, the proliferation of both ECs and EPCs on L(100)H, L(150)H and L(200)H surface were greatly promoted. Another hand, the proliferation activity of SMCs was significantly inhibited on Hep/Ln modified surfaces, which was considered mainly due to the inhibitory effect of heparin to SMCs. According to the existing results, this study demonstrated that in a certain range of heparin and laminin concentration ratio

  20. Evidence of extensive diversity in bacterial adherence mechanisms that exploit unanticipated stainless steel surface structural complexity for biofilm formation.

    Science.gov (United States)

    Davis, Elisabeth M; Li, Dongyang; Shahrooei, Mohammad; Yu, Bin; Muruve, Daniel; Irvin, Randall T

    2013-04-01

    Three protease-resistant bioorganic 304 stainless steel surfaces were created through the reaction of synthetic peptides consisting of the D-enantiomeric isomer (D-K122-4), the retro-inverso D-enantiomeric isomer (RI-K122-4), and a combination of the two peptides (D+RI) of the Pseudomonas aeruginosa PilA receptor binding domain with steel surfaces. The peptides used to produce the new materials differ only in handedness of their three-dimensional structure, but they reacted with the steel to yield materials that differed in their surface electron work function (EWF) while displaying an identical chemical composition and equivalent surface adhesive force properties. These surfaces allowed for an assessment of the relative role of surface EWF in initial biofilm formation. We examined the ability of various bacteria (selected strains of Listeria monocytogenes, L. innocua, Staphylococcus aureus and S. epidermidis) to initiate biofilm formation. The D-K1224 generated surface displayed the lowest EWF (classically associated with greater molecular interactions and more extensive biofilm formation) but was observed to be least effectively colonized by bacteria (>50% decrease in bacterial adherence of all strains). The highest surface EWF with the lowest surface free energy (RI-K122-4 generated) was more extensively colonized by bacteria, with the binding of some strains being equivalent to unmodified steel. The D+RI generated surface was least effective in minimizing biofilm formation, where some strains displayed enhanced bacterial colonization. Fluorescent microscopy revealed that the D and RI peptides displayed similar but clearly different binding patterns, suggesting that the peptides recognized different sites on the steel, and that differential binding of the peptides to the steel surfaces influences the binding of different bacterial strains and species. We have demonstrated that stainless steel surfaces can be easily modified by peptides to generate surfaces with

  1. Numerical Simulation of Atmospheric Boundary Layer Flow Over Battlefield-scale Complex Terrain: Surface Fluxes From Resolved and Subgrid Scales

    Science.gov (United States)

    2015-07-06

    portance to the performance of modern wind farms[26], aerodynamics of vegetative canopies[27, 9] and urban environments[28, 29, 5, 4], and geomorphological...and smooth surfaces at ground level. Water Resour. Res., 11:543–550, 1975. [17] P.R. Owen and W.R. Thomson . Heat transfer across rough surfaces. J

  2. Hepatitis B virus surface antigen (HBsAg and antibody (anti-HBs forming immune complexes in fulminant hepatitis

    Directory of Open Access Journals (Sweden)

    Soares Manoel C.P.

    1999-01-01

    Full Text Available This paper reports an unusual pattern of serological HBV markers and the presence of HBsAg/anti-HBs immune complexes in serum samples from two patients with fulminant hepatitis from the Brazilian Western Amazon Basin. The diagnosis was made by both serologic tests and demonstration of antigen/antibody complexes by transmission electron microscopy. Concurrent Delta virus superinfection is also discussed.

  3. Multifunctional ultra-high vacuum apparatus for studies of the interactions of chemical warfare agents on complex surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wilmsmeyer, Amanda R.; Morris, John R. [Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061 (United States); Gordon, Wesley O.; Mantooth, Brent A.; Lalain, Teri A. [Research and Technology Directorate, U.S. Army Edgewood Chemical Biological Center, Aberdeen Proving Ground, Maryland 21010 (United States); Davis, Erin Durke [OptiMetrics, Inc., Abingdon, Maryland 21009 (United States)

    2014-01-15

    A fundamental understanding of the surface chemistry of chemical warfare agents is needed to fully predict the interaction of these toxic molecules with militarily relevant materials, catalysts, and environmental surfaces. For example, rules for predicting the surface chemistry of agents can be applied to the creation of next generation decontaminants, reactive coatings, and protective materials for the warfighter. Here, we describe a multifunctional ultra-high vacuum instrument for conducting comprehensive studies of the adsorption, desorption, and surface chemistry of chemical warfare agents on model and militarily relevant surfaces. The system applies reflection-absorption infrared spectroscopy, x-ray photoelectron spectroscopy, and mass spectrometry to study adsorption and surface reactions of chemical warfare agents. Several novel components have been developed to address the unique safety and sample exposure challenges that accompany the research of these toxic, often very low vapor pressure, compounds. While results of vacuum-based surface science techniques may not necessarily translate directly to environmental processes, learning about the fundamental chemistry will begin to inform scientists about the critical aspects that impact real-world applications.

  4. 复杂曲面的数控加工误差分析%Error Analysis of the Complex Surface NC Machining

    Institute of Scientific and Technical Information of China (English)

    王振; 韩祥凤

    2011-01-01

    针对复杂曲面的多轴数控加工,应用数学知识建模,从理论上分析了平底铣刀刀具加工复杂曲面时的误差,得出了影响数控加工精度的主要因素并提出了误差补偿方法,为控制多轴数控加工的误兰提供了理论依据与补偿算法,对高精度复杂曲面的数控加工具有借鉴意义.%Complex surfaces are normally manufactured with multi-axis NC machining tools, This paper has applied the mathematical modeling and analyzed the occurring error when the flat milling cutter machining the complex surface in theory. The author found the main reasons affecting the accuracy of NC machining, proposed the method to compensate the error and provided a theoretical basis and the compensation algorithm for the control of multi-axis NC machining, which has the enlightenment to NC machining of the complex curve surface.

  5. Surface enhanced Raman scattering, electronic spectrum, natural bond orbital, and Mulliken charge distribution in the normal modes of diethyldithiocarbamate copper (II) complex, [Cu(DDTC)2].

    Science.gov (United States)

    Téllez Soto, C A; Costa, A C; Ramos, J M; Vieira, L S; Rost, N C V; Versiane, O; Rangel, J L; Mondragón, M A; Raniero, L; Martin, A A

    2013-12-01

    Surface-enhanced Raman scattering (SERS) was used to study the interactions of the normal modes of the diethyldithiocarbamate copper (II) complex, [Cu(DDTC)2] on nano-structured mixture silver-gold surfaces and on silver surfaces. The electronic spectrum of this complex was measured and the charge transfer bands were assigned through the TD-PBE1PBE procedure. Natural bond orbital (NBO) were also carried out to study the Cu(II) hybridation leading to the square planar geometry of the framework of the [Cu(DDTC)2] complex, and to study which are the donor NBO and the acceptor NBO in meaningful charge transfer through the Second Order Perturbation Theory Analysis of the Fox Matrix in NBO basis. To see the electronic dispersion, the Mulliken electronic charges (MAC) were calculated for each normal mode and correlated with the SERS effect. Full assignment of the SERS spectra was also supported by carefully analysis of the distorted geometries generated by the normal modes.

  6. Electron-transfer reactions of cobalt(III) complexes. 1. The kinetic investigation of the reduction of various surfactant cobalt(III) complexes by iron(II) in surface active ionic liquids.

    Science.gov (United States)

    Nagaraj, Karuppiah; Senthil Murugan, Krishnan; Thangamuniyandi, Pilavadi; Sakthinathan, Subramanian

    2015-05-15

    The kinetics of outer sphere electron transfer reaction of surfactant cobalt(III) complex ions, cis-[Co(en)2(C12H25NH2)2](3+) (1), cis-[Co(dp)2(C12H25NH2)2](3+) (2), cis-[Co(trien)(C12H25NH2)2](3+) (3), cis-[Co(bpy)2(C12H25NH2)2](3+) (4) and cis-[Co(phen)2(C12H25NH2)2](3+) (5) (en: ethylenediamine, dp: diaminopropane, trien : triethylenetetramine, bpy: 2,2'-bipyridyl, phen: 1,10-phenanthroline and C12H25NH2 : dodecylamine) have been interrogated by Fe(2+) ion in ionic liquid (1-butyl-3-methylimidazoliumbromide) medium at different temperatures (298, 303, 308, 313, 318 and 323K) by the spectrophotometry method under pseudo first order conditions using an excess of the reductant. Experimentally the reactions were found to be of second order and the electron transfer as outer sphere. The second order rate constant for the electron transfer reaction in ionic liquids was found to increase with increase in the concentration of all these surfactant cobalt(III) complexes. Among these complexes (from en to phen ligand), complex containing the phenanthroline ligand rate is higher compared to other complexes. By assuming the outer sphere mechanism, the results have been explained based on the presence of aggregated structures containing cobalt(III) complexes at the surface of ionic liquids formed by the surfactant cobalt(III) complexes in the reaction medium. The activation parameters (enthalpy of activation ΔH(‡) and entropy of activation ΔS(‡)) of the reaction have been calculated which substantiate the kinetics of the reaction.

  7. A quantitative method to measure biofilm removal efficiency from complex biomaterial surfaces using SEM and image analysis

    Science.gov (United States)

    Vyas, N.; Sammons, R. L.; Addison, O.; Dehghani, H.; Walmsley, A. D.

    2016-09-01

    Biofilm accumulation on biomaterial surfaces is a major health concern and significant research efforts are directed towards producing biofilm resistant surfaces and developing biofilm removal techniques. To accurately evaluate biofilm growth and disruption on surfaces, accurate methods which give quantitative information on biofilm area are needed, as current methods are indirect and inaccurate. We demonstrate the use of machine learning algorithms to segment biofilm from scanning electron microscopy images. A case study showing disruption of biofilm from rough dental implant surfaces using cavitation bubbles from an ultrasonic scaler is used to validate the imaging and analysis protocol developed. Streptococcus mutans biofilm was disrupted from sandblasted, acid etched (SLA) Ti discs and polished Ti discs. Significant biofilm removal occurred due to cavitation from ultrasonic scaling (p dental implants. This imaging and analysis method will be of value to other researchers and manufacturers wishing to study biofilm growth and removal.

  8. Slope of the Slope Derivative Surface used to characterize the complexity of the seafloor around St. John, USVI

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Slope of slope was calculated from the bathymetry surface for each raster cell by applying the ArcGIS Spatial Analyst 'Slope' Tool to a previously created slope...

  9. Multifunctional Ultra-High Vacuum Apparatus for Studies of the Interactions of Chemical Warfare Agents on Complex Surfaces

    Science.gov (United States)

    2014-01-02

    on gamma alumina surfaces. This work was followed by other investigations of organophosphate CWA decomposition on alumina.35 In addition, Wagner and...nm particle di- ameter) was chosen as the first surface to study because the adsorption of many organophosphate molecules (simu- lants) to silica has...Kondratyuk, and J. T. Yates, “Photooxidation of a mus- tard gas simulant over TiO2-SiO2 mixed-oxide photocatalyst: Site poison - ing by oxidation products

  10. A quantitative method to measure biofilm removal efficiency from complex biomaterial surfaces using SEM and image analysis

    Science.gov (United States)

    Vyas, N.; Sammons, R. L.; Addison, O.; Dehghani, H.; Walmsley, A. D.

    2016-01-01

    Biofilm accumulation on biomaterial surfaces is a major health concern and significant research efforts are directed towards producing biofilm resistant surfaces and developing biofilm removal techniques. To accurately evaluate biofilm growth and disruption on surfaces, accurate methods which give quantitative information on biofilm area are needed, as current methods are indirect and inaccurate. We demonstrate the use of machine learning algorithms to segment biofilm from scanning electron microscopy images. A case study showing disruption of biofilm from rough dental implant surfaces using cavitation bubbles from an ultrasonic scaler is used to validate the imaging and analysis protocol developed. Streptococcus mutans biofilm was disrupted from sandblasted, acid etched (SLA) Ti discs and polished Ti discs. Significant biofilm removal occurred due to cavitation from ultrasonic scaling (p SLA surface images were 0.80 ± 0.18 and 0.62 ± 0.20 respectively and 0.74 ± 0.13 and 0.86 ± 0.09 respectively for polished surfaces. Cavitation has potential to be used as a novel way to clean dental implants. This imaging and analysis method will be of value to other researchers and manufacturers wishing to study biofilm growth and removal. PMID:27601281

  11. Effects of low pressure radio frequency discharge on the physical and mechanical characteristics and chemical composition of diffusion coating on a surface of complex configuration details

    Science.gov (United States)

    Ladianov, V. I.; Gilmutdinov, F. Z.; Nikonova, R. M.; Kashapov, N. F.; Shaekhov, M. F.; Khristoliubova, V. I.

    2017-01-01

    The work deals with the influence of low-pressure radio frequency (RF) discharge on the surface properties of metals and their alloys. As objects of research to study the interaction of the jet low pressure RF discharge into the surface of the material the following materials were chosen: tungsten cobalt alloy, high speed steel, structural steel. In the presence of the materials energy parameters of low pressure RF discharge flows in the discharge chamber and the electrode gap were studied. A quantitative assessment of the gas composition inside the chamber to determine the characteristics of the plasma flow, making the major contribution to the modification of the surface was carried out. The influence of the input parameters of the plasma unit on the discharge characteristics was held. Identification of the main processes responsible for the modification of the surface of metals and alloys with the metal sample in the plasma jet and the effect of samples of products complex configuration on its properties is determined. The results of studies of physical and mechanical characteristics and chemical composition of the surface layers of high-speed steels, alloys and steel before and after treatment by low pressure radio frequency discharges with the instrumental indentation methods and X-ray photo-electron spectroscopy. With the help of the quality control system of the inner surfaces tubular products were studied.

  12. Heavy metal contamination and ecological risk assessment in the surface sediments of the coastal area surrounding the industrial complex of Gabes city, Gulf of Gabes, SE Tunisia.

    Science.gov (United States)

    El Zrelli, Radhouan; Courjault-Radé, Pierre; Rabaoui, Lotfi; Castet, Sylvie; Michel, Sylvain; Bejaoui, Nejla

    2015-12-30

    In the present study, the concentrations of 6 trace metals (Hg, Cd, Cu, Pb, Cr and Zn) were assessed in the surface sediments of the central coastal area of Gabes Gulf to determine their contamination status, source, spatial distribution and ecological risks. The ranking of metal contents was found to be Zn>Cd>Cr>Pb>Cu>Hg. Correlation analysis indicated that Cd and Zn derived mainly from the Tunisian Chemical Group phosphogypsum. The other pollutants may originate from other industrial wastes. Metallic contamination was detected in the south of chemical complex, especially in the inter-harbor zone, where the ecological risk of surface sediments is the highest, implying potential negative impacts of industrial pollutants. The spatial distribution of pollutants seems to be due to the effect of harbor installations and coastal currents. The metallic pollution status of surface sediments of Gabes Gulf is obvious, very worrying and requires rapid intervention.

  13. Analysis of COPII Vesicles Indicates a Role for the Emp47-Ssp120 Complex in Transport of Cell Surface Glycoproteins.

    Science.gov (United States)

    Margulis, Neil G; Wilson, Joshua D; Bentivoglio, Christine M; Dhungel, Nripesh; Gitler, Aaron D; Barlowe, Charles

    2016-03-01

    Coat protein complex II (COPII) vesicle formation at the endoplasmic reticulum (ER) transports nascent secretory proteins forward to the Golgi complex. To further define the machinery that packages secretory cargo and targets vesicles to Golgi membranes, we performed a comprehensive proteomic analysis of purified COPII vesicles. In addition to previously known proteins, we identified new vesicle proteins including Coy1, Sly41 and Ssp120, which were efficiently packaged into COPII vesicles for trafficking between the ER and Golgi compartments. Further characterization of the putative calcium-binding Ssp120 protein revealed a tight association with Emp47 and in emp47Δ cells Ssp120 was mislocalized and secreted. Genetic analyses demonstrated that EMP47 and SSP120 display identical synthetic positive interactions with IRE1 and synthetic negative interactions with genes involved in cell wall assembly. Our findings support a model in which the Emp47-Ssp120 complex functions in transport of plasma membrane glycoproteins through the early secretory pathway.

  14. Sensitivity of model parameterizations for simulated latent heat flux at the snow surface for complex mountain sites

    Science.gov (United States)

    The snowcover energy balance is typically dominated by net radiation and sensible and latent heat fluxes. Validation of the two latter components is rare and often difficult to undertake at complex mountain sites. Latent heat flux, the focus of this paper, is the primary coupling mechanism between...

  15. Quartz crystal microbalance: a useful tool for studying thin polymer films and complex biomolecular systems at the solution-surface interface.

    Science.gov (United States)

    Marx, Kenneth A

    2003-01-01

    The quartz crystal microbalance (QCM) is a simple, cost effective, high-resolution mass sensing technique, based upon the piezoelectric effect. As a methodology, the QCM evolved a solution measurement capability in largely analytical chemistry and electrochemistry applications due to its sensitive solution-surface interface measurement capability. The technique possesses a wide detection range. At the low mass end, it can detect monolayer surface coverage by small molecules or polymer films. At the upper end, it is capable of detecting much larger masses bound to the surface. These can be complex arrays of biopolymers and biomacromolecules, even whole cells. In addition, the QCM can provide information about the energy dissipating properties of the bound surface mass. Another important and unique feature of the technique is the ability to measure mass and energy dissipation properties of films while simultaneously carrying out electrochemistry on solution species or upon film systems bound to the upper electrode on the oscillating quartz crystal surface. These measurements can describe the course of electropolymerization of a film or can reveal ion or solute transport within a film during changes in the film environment or state, including the oxidation state for an electroactive film driven by the underlying surface potential. The past decade has witnessed an explosive growth in the application of the QCM technique to the study of a wide range of molecular systems at the solution-surface interface, in particular, biopolymer and biochemical systems. In this report, we start with a brief historical and technical overview. Then we discuss the application of the QCM technique to measurements involving micellar systems, self-assembling monolayers and their phase transition behavior, molecularly imprinted polymers, chemical sensors, films formed using the layer-by-layer assembly technique, and biopolymer films and point out the utility of the electrochemical

  16. The effect of spatial micro-CT image resolution and surface complexity on the morphological 3D analysis of open porous structures

    Energy Technology Data Exchange (ETDEWEB)

    Pyka, Grzegorz, E-mail: gregory.pyka@mtm.kuleuven.be [Department of Metallurgy and Materials Engineering, KU Leuven, Kasteelpark Arenberg 44 – PB2450, B-3001 Leuven (Belgium); Kerckhofs, Greet [Department of Metallurgy and Materials Engineering, KU Leuven, Kasteelpark Arenberg 44 – PB2450, B-3001 Leuven (Belgium); Biomechanics Research Unit, Université de Liege, Chemin des Chevreuils 1 - BAT 52/3, B-4000 Liège (Belgium); Schrooten, Jan; Wevers, Martine [Department of Metallurgy and Materials Engineering, KU Leuven, Kasteelpark Arenberg 44 – PB2450, B-3001 Leuven (Belgium)

    2014-01-15

    In material science microfocus X-ray computed tomography (micro-CT) is one of the most popular non-destructive techniques to visualise and quantify the internal structure of materials in 3D. Despite constant system improvements, state-of-the-art micro-CT images can still hold several artefacts typical for X-ray CT imaging that hinder further image-based processing, structural and quantitative analysis. For example spatial resolution is crucial for an appropriate characterisation as the voxel size essentially influences the partial volume effect. However, defining the adequate image resolution is not a trivial aspect and understanding the correlation between scan parameters like voxel size and the structural properties is crucial for comprehensive material characterisation using micro-CT. Therefore, the objective of this study was to evaluate the influence of the spatial image resolution on the micro-CT based morphological analysis of three-dimensional (3D) open porous structures with a high surface complexity. In particular the correlation between the local surface properties and the accuracy of the micro-CT-based macro-morphology of 3D open porous Ti6Al4V structures produced by selective laser melting (SLM) was targeted and revealed for rough surfaces a strong dependence of the resulting structure characteristics on the scan resolution. Reducing the surface complexity by chemical etching decreased the sensitivity of the overall morphological analysis to the spatial image resolution and increased the detection limit. This study showed that scan settings and image processing parameters need to be customized to the material properties, morphological parameters under investigation and the desired final characteristics (in relation to the intended functional use). Customization of the scan resolution can increase the reliability of the micro-CT based analysis and at the same time reduce its operating costs. - Highlights: • We examine influence of the image resolution

  17. Contribution of ground surface altitude difference to thermal anomaly detection using satellite images: Application to volcanic/geothermal complexes in the Andes of Central Chile

    Science.gov (United States)

    Gutiérrez, Francisco J.; Lemus, Martín; Parada, Miguel A.; Benavente, Oscar M.; Aguilera, Felipe A.

    2012-09-01

    Detection of thermal anomalies in volcanic-geothermal areas using remote sensing methodologies requires the subtraction of temperatures, not provided by geothermal manifestations (e.g. hot springs, fumaroles, active craters), from satellite image kinetic temperature, which is assumed to correspond to the ground surface temperature. Temperatures that have been subtracted in current models include those derived from the atmospheric transmittance, reflectance of the Earth's surface (albedo), topography effect, thermal inertia and geographic position effect. We propose a model that includes a new parameter (K) that accounts for the variation of temperature with ground surface altitude difference in areas where steep relief exists. The proposed model was developed and applied, using ASTER satellite images, in two Andean volcanic/geothermal complexes (Descabezado Grande-Cerro Azul Volcanic Complex and Planchón-Peteroa-Azufre Volcanic Complex) where field data of atmosphere and ground surface temperature as well as radiation for albedo calibration were obtained in 10 selected sites. The study area was divided into three zones (Northern, Central and Southern zones) where the thermal anomalies were obtained independently. K value calculated for night images of the three zones are better constrained and resulted to be very similar to the Environmental Lapse Rate (ELR) determined for a stable atmosphere (ELR > 7 °C/km). Using the proposed model, numerous thermal anomalies in areas of ≥ 90 m × 90 m were identified that were successfully cross-checked in the field. Night images provide more reliable information for thermal anomaly detection than day images because they record higher temperature contrast between geothermal areas and its surroundings and correspond to more stable atmospheric condition at the time of image acquisition.

  18. A Gradient-Simulated Annealing Algorithm of Pre-location-Based Best Fitting of Blank to Complex Surfaces Machining

    Institute of Scientific and Technical Information of China (English)

    MALi-ming; JIANGHong; WANGXiao-chun

    2004-01-01

    The algorithm is divided into two steps. The first step pre-locates the blank by aligning its centre of gravity and approximate normal vector with those of destination surfaces, with largest overlap of projections of two objects on a plane perpendicular to the normal vector. The second step is optimizing an objective function by means of gradient-simulated annealing algorithm to get the best matching of a set of distributed points on the blank and destination surfaces. An example for machining hydroelectric turbine blades is given to verify the effectiveness of algorithm.

  19. New five coordinated supramolecular structured cadmium complex as precursor for CdO nanoparticles: Synthesis, crystal structure, theoretical and 3D Hirshfeld surface analyses

    Science.gov (United States)

    Ghanbari Niyaky, S.; Montazerozohori, M.; Masoudiasl, A.; White, J. M.

    2017-03-01

    In this paper, a combined experimental and theoretical study on a new CdLBr2 complex (L = N1-(2-bromobenzylidene)-N2-(2-((E)-(2-bromobenzylidene) amino)ethyl) ethane-1,2-diamine) synthesized via template method, is described. The crystal structure analysis of the complex indicates that, the Cd(II) ion is centered in a distorted square pyramidal space constructed by three iminic nitrogens of the ligand as well as two bromide anions. More analysis of crystal packing proposed a supramolecular structure stabilized by some non-covalent interactions such as Br⋯Br and Xsbnd H⋯Br (X = N and C) in solid state. Furthermore, 3D Hirshfeld surface analyses and DFT studies were applied for theoretical investigation of the complexes. Theoretical achievements were found in a good agreement with respect to the experimental data. To evaluate the nature of bonding and the strength of the intra and inter-molecular interactions a natural bond orbital (NBO) analysis on the complex structure was performed. Time dependent density functional theory (TD-DFT) was also applied to predict the electronic spectral data of the complex as compared with the experimental ones. CdLBr2 complex as nano-structure compound was also prepared under ultrasonic conditions and characterized by scanning electron microscopy (SEM) and X-ray powder diffraction (XRPD). Finally, it was found that the cadmium complex can be used as a suitable precursor for preparation of CdO nanoparticles via calcination process at 600 °C under air atmosphere.

  20. On the stability of the polymer brushes formed by adsorption of Ionomer Complexes on hydrophilic and hydrophobic surfaces

    NARCIS (Netherlands)

    Brzozowska, A. M.; Spruijt, E.; de Keizer, A.; Stuart, M. A. Cohen; Norde, W.

    2011-01-01

    We have studied the effect of normal forces and shear forces on the stability and functionality of a polymer brush layer formed upon adsorption of polymeric micelles on hydrophilic and hydrophobic surfaces. The micelles consist of oppositely charged polyelectrolyte blocks (poly(acrylic acid) and pol

  1. The cell surface expression of SAP-binding receptor CD229 is regulated via its interaction with clathrin-associated adaptor complex 2 (AP-2).

    Science.gov (United States)

    Del Valle, Juana M; Engel, Pablo; Martín, Margarita

    2003-05-09

    CD229 (Ly9) is a cell surface receptor selectively expressed on T and B lymphocytes, and it belongs to the CD150 receptor family. Like other receptors of this family, CD229 interacts with SAP/SH2D1a protein, mutation of which is responsible for the fatal X-linked lymphoproliferative disease. Receptors of the CD150 family function as costimulatory molecules, regulating cytokine production and cytotoxicity. Thus, their signaling and regulation in lymphocytes may be critical to an understanding of the pathogenesis of the X-linked lymphoproliferative disease. Here we show that CD229 interacts with the mu(2) chain of the AP-2 adaptor complex that links transmembrane proteins to clathrin-coated pits. CD229 was the only member of the CD150 family associated with AP-2. We also show that the mu(2) chain interacts with the Y(470)EKL motif of CD229. The integrity of this site was necessary for CD229 internalization, but it was not involved in SAP recruitment. Moreover, CD229 binds to the AP-2 complex in T and B cell lines, and it is internalized rapidly from the cell surface on T cells after antibody ligation. In contrast, cross-linking of CD229 receptors with intact antibody inhibited CD229 internalization on B cells. However, when F(ab')(2) antibodies were used, CD229 internalization was similar on T and B cells, suggesting that Fcgamma receptors control CD229 cell surface expression. Furthermore, CD229 was regulated by T cell receptor and B cell receptor signaling because coligation with antibodies against anti-CD3 and anti-IgM increased the rate of CD229 endocytosis. These data suggest that CD229 cell surface expression on lymphocytes surface is strongly and differentially regulated within the CD150 family members.

  2. Surface enhanced Raman scattering, natural bond orbitals and Mulliken atomic charge distribution in the normal modes of diethyldithiocarbamate cadmium (II) complex, [Cd(DDTC)2

    Science.gov (United States)

    Téllez Soto, C. A.; Costa, A. C.; Versiane, O.; Lemma, T.; Machado, N. C. F.; Mondragón, M. A.; Martin, A. A.

    2015-07-01

    Theoretical and experimental bands have been assigned to the Fourier Transform Infrared (FT-IR) and FT-Raman spectra of the bis(diethyldithiocarbamate)Cd(II) complex, abbreviated as ([Cd(DDTC)2]). The calculations and spectral interpretation have been based on the DFT/B3LYP method, infrared and Raman second derivative spectra, and band deconvolution analysis to assist in the assignment of observed fundamentals. This study validated the unusual pseudo tetrahedral molecular structure formed around the Cd(II) cation. Surface-enhanced Raman scattering (SERS) was used to determine the interactions of the normal-modes of the diethyldithiocarbamate cadmium (II) complex on nano-structured silver surfaces. Natural bond orbital (NBO) analysis was also carried out to study the Cd(II) hybridization causing the pseudo tetrahedral geometry of the framework of the [Cd(DDTC)2] complex, and to confirm the charge transfer mechanisms through second order perturbation theory analysis of the Fox Matrix. In order to find out the electronic dispersion of the Mulliken atomic charges (MAC) in the normal modes, we calculated the MAC for each normal mode and correlated these values with the SERS effect. Experimental UV-Vis spectra were obtained and charge transfer bands were assigned. Good agreement between the calculated and experimental values for the vibrational and UV-Vis spectra was obtained.

  3. Synthesis and luminescent properties of the novel poly(ethylene-co-acrylic acid) films based on surface modification with lanthanide (Eu3+, Tb3+) complexes

    Science.gov (United States)

    Wu, Yuewen; Chu, Yang; Yu, Zhenjiang; Hao, Haixia; Wu, Qingyao; Xie, Hongde

    2017-10-01

    Two kinds of novel fluorescent films have been successfully synthesized by surface modification on the poly(ethylene-co-acrylic acid) films using the lanthanide (Eu3+, Tb3+) complexes. The process consists of three steps: conversion of carboxylic acid groups on the surface of the poly(ethylene-co-acrylic acid) films to acid chloride groups, synthesis of the lanthanide complexes bearing amino groups, and amidation to form the modified films. To characterize the modified films, Fourier transform infrared, thermogravimetric analysis, static water contact angle measurements and photoluminescence tests have been employed. Fourier transform infrared verifies the successful preparation of the lanthanide complexes and the modified poly(ethylene-co-acrylic acid) films. These films can emit strong characteristic red and green light under UV light excitation. In addition, the films both have short lifetime (1.14 ms and 1.21 ms), high thermal stability (Td = 408 °C and 411 °C) and, compared with unmodified ones, increased hydrophilicity. All these results suggest that the modified films have potential application as luminescent materials under high temperature.

  4. Hydrido-ruthenium cluster complexes as models for reactive surface hydrogen species of ruthenium nanoparticles. Solid-state 2H NMR and quantum chemical calculations.

    Science.gov (United States)

    Gutmann, Torsten; Walaszek, Bernadeta; Yeping, Xu; Wächtler, Maria; del Rosal, Iker; Grünberg, Anna; Poteau, Romuald; Axet, Rosa; Lavigne, Guy; Chaudret, Bruno; Limbach, Hans-Heinrich; Buntkowsky, Gerd

    2010-08-25

    The (2)H quadrupolar interaction is a sensitive tool for the characterization of deuterium-metal binding states. In the present study, experimental solid-state (2)H MAS NMR techniques are used in the investigations of two ruthenium clusters, D(4)Ru(4)(CO)(12) (1) and D(2)Ru(6)(CO)(18) (2), which serve as model compounds for typical two-fold, three-fold, and octahedral coordination sites on metal surfaces. By line-shape analysis of the (2)H MAS NMR measurements of sample 1, a quadrupolar coupling constant of 67 +/- 1 kHz, an asymmetry parameter of 0.67 +/- 0.1, and an isotropic chemical shift of -17.4 ppm are obtained. In addition to the neutral complex, sample 2 includes two ionic clusters, identified as anionic [DRu(6)(CO)(18)](-) (2(-)) and cationic [D(3)Ru(6)(CO)(18)](+) (2(+)). By virtue of the very weak quadrupolar interaction (Quantum chemical DFT calculations at different model structures for these ruthenium clusters were arranged in order to help in the interpretation of the experimental results. It is shown that the (2)H nuclear quadrupolar interaction is a sensitive tool for distinguishing the binding state of the deuterons to the transition metal. Combining the data from the polynuclear complexes with the data from mononuclear complexes, a molecular ruler for quadrupolar interactions is created. This ruler now permits the solid-state NMR spectroscopic characterization of deuterium adsorbed on the surfaces of catalytically active metal nanoparticles.

  5. Preparation and surface functionalization of MWCNTs: study of the composite materials produced by the interaction with an iron phthalocyanine complex.

    Science.gov (United States)

    Asedegbega-Nieto, Esther; Pérez-Cadenas, María; Carter, Jonathan; Anderson, James A; Guerrero-Ruiz, Antonio

    2011-04-20

    Carbon nanotubes [CNTs] were synthesized by the catalytic vapor decomposition method. Thereafter, they were functionalized in order to incorporate the oxygen groups (OCNT) and subsequently the amine groups (ACNT). All three CNTs (the as-synthesized and functionalized) underwent reaction with an iron organometallic complex (FePcS), iron(III) phthalocyanine-4,4",4",4"-tetrasulfonic acid, in order to study the nature of the interaction between this complex and the CNTs and the potential formation of nanocomposite materials. Transmission electronic microscopy, N2 adsorption at 77 K, thermogravimetric analysis, temperature-programmed desorption, and X-ray photoelectron spectroscopy were the characterization techniques employed to confirm the successful functionalization of CNTs as well as the type of interaction existing with the FePcS. All results obtained led to the same conclusion: There were no specific chemical interactions between CNTs and the fixed FePcS.

  6. Preparation and surface functionalization of MWCNTs: study of the composite materials produced by the interaction with an iron phthalocyanine complex

    Directory of Open Access Journals (Sweden)

    Carter Jonathan

    2011-01-01

    Full Text Available Abstract Carbon nanotubes [CNTs] were synthesized by the catalytic vapor decomposition method. Thereafter, they were functionalized in order to incorporate the oxygen groups (OCNT and subsequently the amine groups (ACNT. All three CNTs (the as-synthesized and functionalized underwent reaction with an iron organometallic complex (FePcS, iron(III phthalocyanine-4,4",4",4""-tetrasulfonic acid, in order to study the nature of the interaction between this complex and the CNTs and the potential formation of nanocomposite materials. Transmission electronic microscopy, N2 adsorption at 77 K, thermogravimetric analysis, temperature-programmed desorption, and X-ray photoelectron spectroscopy were the characterization techniques employed to confirm the successful functionalization of CNTs as well as the type of interaction existing with the FePcS. All results obtained led to the same conclusion: There were no specific chemical interactions between CNTs and the fixed FePcS.

  7. Equine herpesvirus type 4 UL56 and UL49.5 proteins downregulate cell surface major histocompatibility complex class I expression independently of each other.

    Science.gov (United States)

    Said, Abdelrahman; Azab, Walid; Damiani, Armando; Osterrieder, Nikolaus

    2012-08-01

    Major histocompatibility complex class I (MHC-I) molecules are critically important in the host defense against various pathogens through presentation of viral peptides to cytotoxic T lymphocytes (CTLs), a process resulting in the destruction of virus-infected cells. Herpesviruses interfere with CTL-mediated elimination of infected cells by various mechanisms, including inhibition of peptide transport and loading, perturbation of MHC-I trafficking, and rerouting and proteolysis of cell surface MHC-I. In this study, we show that equine herpesvirus type 4 (EHV-4) modulates MHC-I cell surface expression through two different mechanisms. First, EHV-4 can lead to a significant downregulation of MHC-I expression at the cell surface through the product of ORF1, a protein expressed with early kinetics from a gene that is homologous to herpes simplex virus 1 UL56. The EHV-4 UL56 protein reduces cell surface MHC-I as early as 4 h after infection. Second, EHV-4 can interfere with MHC-I antigen presentation, starting at 6 h after infection, by inhibition of the transporter associated with antigen processing (TAP) through its UL49.5 protein. Although pUL49.5 has no immediate effect on overall surface MHC-I levels in infected cells, it blocks the supply of antigenic peptides to the endoplasmic reticulum (ER) and transport of peptide-loaded MHC-I to the cell surface. Taken together, our results show that EHV-4 encodes at least two viral immune evasion proteins: pUL56 reduces MHC-I molecules on the cell surface at early times after infection, and pUL49.5 interferes with MHC-I antigen presentation by blocking peptide transport in the ER.

  8. Groundwater and surface-water interaction and effects of pumping in a complex glacial-sediment aquifer, phase 2, east-central Massachusetts

    Science.gov (United States)

    Eggleston, Jack R.; Zarriello, Phillip J.; Carlson, Carl S.

    2015-12-31

    The U.S. Geological Survey, in cooperation with the Town of Framingham, Massachusetts, has investigated the potential of proposed groundwater withdrawals at the Birch Road well site to affect nearby surface water bodies and wetlands, including Lake Cochituate, the Sudbury River, and the Great Meadows National Wildlife Refuge in east-central Massachusetts. In 2012, the U.S. Geological Survey developed a Phase 1 numerical groundwater model of a complex glacial-sediment aquifer to synthesize hydrogeologic information and simulate potential future pumping scenarios. The model was developed with MODFLOW-NWT, an updated version of a standard USGS numerical groundwater flow modeling program that improves solution of unconfined groundwater flow problems. The groundwater model and investigations of the aquifer improved understanding of groundwater–surface-water interaction and the effects of groundwater withdrawals on surface-water bodies and wetlands in the study area. The initial work also revealed a need for additional information and model refinements to better understand this complex aquifer system.

  9. The role of surface electrostatics on the stability, function and regulation of human cystathionine β-synthase, a complex multidomain and oligomeric protein.

    Science.gov (United States)

    Pey, Angel L; Majtan, Tomas; Kraus, Jan P

    2014-09-01

    Human cystathionine β-synthase (hCBS) is a key enzyme of sulfur amino acid metabolism, controlling the commitment of homocysteine to the transsulfuration pathway and antioxidant defense. Mutations in hCBS cause inherited homocystinuria (HCU), a rare inborn error of metabolism characterized by accumulation of toxic homocysteine in blood and urine. hCBS is a complex multidomain and oligomeric protein whose activity and stability are independently regulated by the binding of S-adenosyl-methionine (SAM) to two different types of sites at its C-terminal regulatory domain. Here we study the role of surface electrostatics on the complex regulation and stability of hCBS using biophysical and biochemical procedures. We show that the kinetic stability of the catalytic and regulatory domains is significantly affected by the modulation of surface electrostatics through noticeable structural and energetic changes along their denaturation pathways. We also show that surface electrostatics strongly affect SAM binding properties to those sites responsible for either enzyme activation or kinetic stabilization. Our results provide new insight into the regulation of hCBS activity and stability in vivo with implications for understanding HCU as a conformational disease. We also lend experimental support to the role of electrostatic interactions in the recently proposed binding modes of SAM leading to hCBS activation and kinetic stabilization.

  10. Vaspin is an adipokine ameliorating ER stress in obesity as a ligand for cell-surface GRP78/MTJ-1 complex.

    Science.gov (United States)

    Nakatsuka, Atsuko; Wada, Jun; Iseda, Izumi; Teshigawara, Sanae; Higashio, Kanji; Murakami, Kazutoshi; Kanzaki, Motoko; Inoue, Kentaro; Terami, Takahiro; Katayama, Akihiro; Hida, Kazuyuki; Eguchi, Jun; Horiguchi, Chikage Sato; Ogawa, Daisuke; Matsuki, Yasushi; Hiramatsu, Ryuji; Yagita, Hideo; Kakuta, Shigeru; Iwakura, Yoichiro; Makino, Hirofumi

    2012-11-01

    It is unknown whether adipokines derived from adipose tissues modulate endoplasmic reticulum (ER) stress induced in obesity. Here, we show that visceral adipose tissue-derived serine protease inhibitor (vaspin) binds to cell-surface 78-kDa glucose-regulated protein (GRP78), which is recruited from ER to plasma membrane under ER stress. Vaspin transgenic mice were protected from diet-induced obesity, glucose intolerance, and hepatic steatosis, while vaspin-deficient mice developed glucose intolerance associated with upregulation of ER stress markers. With tandem affinity tag purification using HepG2 cells, we identified GRP78 as an interacting molecule. The complex formation of vaspin, GRP78, and murine tumor cell DnaJ-like protein 1 (MTJ-1) (DnaJ homolog, subfamily C, member 1) on plasma membrane was confirmed by cell-surface labeling with biotin and immunoprecipitation in liver tissues and H-4-II-E-C3 cells. The addition of recombinant human vaspin in the cultured H-4-II-E-C3 cells also increased the phosphorylation of Akt and AMP-activated protein kinase (AMPK) in a dose-dependent manner, and anti-GRP78 antibodies completely abrogated the vaspin-induced upregulation of pAkt and pAMPK. Vaspin is a novel ligand for cell-surface GRP78/MTJ-1 complex, and its subsequent signals exert beneficial effects on ER stress-induced metabolic dysfunctions.

  11. Crystal Structure of Botulinum Neurotoxin Type a in Complex With the Cell Surface Co-Receptor GT1b-Insight Into the Toxin-Neuron Interaction

    Energy Technology Data Exchange (ETDEWEB)

    Stenmark, P.; Dupuy, J.; Inamura, A.; Kiso, M.; Stevens, R.C.

    2009-05-26

    Botulinum neurotoxins have a very high affinity and specificity for their target cells requiring two different co-receptors located on the neuronal cell surface. Different toxin serotypes have different protein receptors; yet, most share a common ganglioside co-receptor, GT1b. We determined the crystal structure of the botulinum neurotoxin serotype A binding domain (residues 873-1297) alone and in complex with a GT1b analog at 1.7 A and 1.6 A, respectively. The ganglioside GT1b forms several key hydrogen bonds to conserved residues and binds in a shallow groove lined by Tryptophan 1266. GT1b binding does not induce any large structural changes in the toxin; therefore, it is unlikely that allosteric effects play a major role in the dual receptor recognition. Together with the previously published structures of botulinum neurotoxin serotype B in complex with its protein co-receptor, we can now generate a detailed model of botulinum neurotoxin's interaction with the neuronal cell surface. The two branches of the GT1b polysaccharide, together with the protein receptor site, impose strict geometric constraints on the mode of interaction with the membrane surface and strongly support a model where one end of the 100 A long translocation domain helix bundle swing into contact with the membrane, initiating the membrane anchoring event.

  12. Potentiometric surfaces of the Arnold Engineering Development Complex Area, Arnold Air Force Base, Tennessee, May and September 2011

    Science.gov (United States)

    Haugh, Connor J.; Robinson, John A.

    2016-01-29

    Arnold Air Force Base occupies about 40,000 acres in Coffee and Franklin Counties, Tennessee. The primary mission of Arnold Air Force Base is to provide risk-reduction information in the development of aerospace products through test and evaluation. This mission is achieved in part through test facilities at Arnold Engineering Development Complex (AEDC), which occupies about 4,000 acres in the center of Arnold Air Force Base. Arnold Air Force Base is underlain by gravel and limestone aquifers, the most productive of which is the Manchester aquifer. Several volatile organic compounds, primarily chlorinated solvents, have been identified in the groundwater at Arnold Air Force Base. In 2011, the U.S. Geological Survey, in cooperation with the U.S. Air Force, Arnold Air Force Base, completed a study of groundwater flow focused on the Arnold Engineering Development Complex area. The Arnold Engineering Development Complex area is of particular concern because within this area (1) chlorinated solvents have been identified in the groundwater, (2) the aquifers are dewatered around below-grade test facilities, and (3) there is a regional groundwater divide.

  13. Well-Defined Molybdenum Oxo Alkyl Complex Supported on Silica by Surface Organometallic Chemistry: A Highly Active Olefin Metathesis Precatalyst.

    Science.gov (United States)

    Merle, Nicolas; Le Quéméner, Frédéric; Bouhoute, Yassine; Szeto, Kai C; De Mallmann, Aimery; Barman, Samir; Samantaray, Manoja K; Delevoye, Laurent; Gauvin, Régis M; Taoufik, Mostafa; Basset, Jean-Marie

    2017-02-15

    The well-defined silica-supported molybdenum oxo alkyl species (≡SiO-)MoO(CH2(t)Bu)3 was selectively prepared by grafting of MoO(CH2(t)Bu)3Cl onto partially dehydroxylated silica (silica700) using the surface organometallic chemistry approach. This surface species was fully characterized by elemental analysis and DRIFT, solid-state NMR, and EXAFS spectroscopy. This new material is related to the active species of industrial supported MoO3/SiO2 olefin metathesis catalysts. It displays very high activity in propene self-metathesis at mild (turnover number = 90 000 after 25 h). Remarkably, its catalytic performance outpaces those of the parent imido derivative and its tungsten oxo analogue.

  14. Self-assembled alkanethiol monolayers on gold surfaces: resolving the complex structure at the interface by STM.

    Science.gov (United States)

    Guo, Quanmin; Li, Fangsen

    2014-09-28

    The surface properties of metals and metal oxides can be modified by adding a single layer of organic molecules. A most popular route for depositing such a molecular layer is via the formation of self-assembled monolayers (SAMs). The molecules that form SAMs have a functionality which binds to the surface and the adsorption is self-regulated to terminate at exactly one single molecular layer. The very first example, which has become the most widely studied system, of SAMs on metal surfaces consists of chemisorbed alkylthiolate on gold. Despite the simplicity in the preparation of alkanethiol SAMs and the seemingly straightforward structure of such SAMs, the detailed bonding between the sulfur head group and gold is still subject to debate. Experimental and theoretical effort in the last six years has led to a much improved understanding of this classical system of SAMs. In this review, we will highlight the most recent progress in the study of the interfacial structure of alkanethiol SAMs on gold. We focus on the important phenomenon of phase transition that occurs from n-propanethiol to n-butanethiol, and propose a unified structural model to explain how the (3 × 4) phase for short chain alkanethiol monolayers (methyl-, ethyl- and propylthiolate monolayers) changes into the (3 × 2√3)-rect./c(4 × 2) phase for long chain molecular monolayers.

  15. Surface complex formation between aliphatic nitrile molecules and transition metal atoms for thermally stable lithium-ion batteries.

    Science.gov (United States)

    Kim, Young-Soo; Lee, Hochun; Song, Hyun-Kon

    2014-06-11

    Non-flammability of electrolyte and tolerance of cells against thermal abuse should be guaranteed for widespread applications of lithium-ion batteries (LIBs). As a strategy to improve thermal stability of LIBs, here, we report on nitrile-based molecular coverage on surface of cathode active materials to block or suppress thermally accelerated side reactions between electrode and electrolyte. Two different series of aliphatic nitriles were introduced as an additive into a carbonate-based electrolyte: di-nitriles (CN-[CH2]n-CN with n = 2, 5, and 10) and mono-nitriles (CH3-[CH2]m-CN with m = 2, 5, and 10). On the basis of the strong interaction between the electronegativity of nitrile functional groups and the electropositivity of cobalt in LiCoO2 cathode, aliphatic mono- and di-nitrile molecules improved the thermal stability of lithium ion cells by efficiently protecting the surface of LiCoO2. Three factors, the surface coverage θ, the steric hindrance of aliphatic moiety within nitrile molecule, and the chain polarity, mainly affect thermal tolerance as well as cell performances at elevated temperature.

  16. Locally induced surface air confluence by complex terrain and its effects on air pollution in the valley of Mexico

    Science.gov (United States)

    Jazcilevich, Aron D.; García, Agustín R.; Caetano, Ernesto

    Using a meteorological computational model it is shown how, in the Valley of Mexico, a high pressure system together with the complex orography of the region induce the formation of a local confluence line. With the aid of a prognostic air quality model it is shown that the maximum pollutant mixing ratios are placed on and follow the confluence line which crosses over the most populated areas of Mexico City. This phenomenon provides an explanation of why and when pollutants assume its geographical distribution in the valley during high mixing ratio episodes.

  17. A Comparison of Machine Learning Algorithms for Mapping of Complex Surface-Mined and Agricultural Landscapes Using ZiYuan-3 Stereo Satellite Imagery

    Directory of Open Access Journals (Sweden)

    Xianju Li

    2016-06-01

    Full Text Available Land cover mapping (LCM in complex surface-mined and agricultural landscapes could contribute greatly to regulating mine exploitation and protecting mine geo-environments. However, there are some special and spectrally similar land covers in these landscapes which increase the difficulty in LCM when employing high spatial resolution images. There is currently no research on these mixed complex landscapes. The present study focused on LCM in such a mixed complex landscape located in Wuhan City, China. A procedure combining ZiYuan-3 (ZY-3 stereo satellite imagery, the feature selection (FS method, and machine learning algorithms (MLAs (random forest, RF; support vector machine, SVM; artificial neural network, ANN was proposed and first examined for both LCM of surface-mined and agricultural landscapes (MSMAL and classification of surface-mined land (CSML, respectively. The mean and standard deviation filters of spectral bands and topographic features derived from ZY-3 stereo images were newly introduced. Comparisons of three MLAs, including their sensitivities to FS and whether FS resulted in significant influences, were conducted for the first time in the present study. The following conclusions are drawn. Textures were of little use, and the novel features contributed to improve classification accuracy. Regarding the influence of FS: FS substantially reduced feature set (by 68% for MSMAL and 87% for CSML, and often improved classification accuracies (with an average value of 4.48% for MSMAL using three MLAs, and 11.39% for CSML using RF and SVM; FS showed statistically significant improvements except for ANN-based MSMAL; SVM was most sensitive to FS, followed by ANN and RF. Regarding comparisons of MLAs: for MSMAL based on feature subset, RF achieved the greatest overall accuracy of 77.57%, followed by SVM and ANN; for CSML, SVM had the highest accuracies (87.34%, followed by RF and ANN; based on the feature subsets, significant differences were

  18. Potential of surface complexation and redox modeling for chromium(VI) adsorption on local materials as liners for waste containment facilities

    OpenAIRE

    MOHAMMED, Syed Abu Sayeed

    2013-01-01

    The main aim of this paper was to model the behavior of red soil and black cotton soil along with fly ash mixture to sorption of chromium at different ranges of pH. Visual MINTEQ version 3.0 was used; it was found that the model predicted the behavior accurately and this was compared with an experimental work done earlier. By conducting this simulation study, it was found that surface complexation and reduction played an important role in the sorption process, which gave a new impetus...

  19. A silica-supported double-decker silsesquioxane provides a second skin for the selective generation of bipodal surface organometallic complexes

    KAUST Repository

    Espinas, Jeff

    2012-11-12

    A well-defined silica-based material with a homogeneous nanolayer presenting identical pairs of vicinal silanols has been prepared by reaction of the surface organometallic species [≡SiOZr(CH 2CMe 3) 3], obtained on a silica dehydroxylated at 900 °C, with the double-decker-shaped silsesquioxane (OH) 2DD(OH) 2. The surface structure has been established using extensive NMR characterization ( 1H, 13C, 29Si, HETCOR, double-quantum, triple-quantum). Treatment with Zr(CH 2CMe 3) 4 leads to the first well-defined single-site bipodal grafted bis-neopentyl zirconium complex. © 2012 American Chemical Society.

  20. Enhanced performance of dye-sensitized solar cells with dual-function coadsorbent: reducing the surface concentration of dye-iodine complexes concomitant with attenuated charge recombination.

    Science.gov (United States)

    Mazloum-Ardakani, Mohammad; Khoshroo, Alireza

    2015-09-21

    In this paper, we have investigated the effects of oleic acid as a dual-function coadsorbent on recombination and iodine binding in dye-sensitized solar cells. Oleic acid as a dual-function coadsorbent effectively shields the back electron transfer from TiO2 to I3(-) ions and also reduces the surface concentration of dye-I2 complexes via iodine binding to the unsaturated double bond on oleic acid. It was found that interaction between iodine and the double bond of oleic acid keeps the iodine molecules away from the surface and reduces the recombination rate between injected electrons in a semiconductor and iodine molecules and also increases open-circuit voltage. Furthermore, the interaction between iodine molecules and unexcited dyes affects the UV-Vis spectrum of them and prevents an unfavorable blue shift. Overall, the results point to an improved performance for DSC operation and development.

  1. Simulation of groundwater and surface-water interaction and effects of pumping in a complex glacial-sediment aquifer, east central Massachusetts

    Science.gov (United States)

    Eggleston, Jack R.; Carlson, Carl S.; Fairchild, Gillian M.; Zarriello, Phillip J.

    2012-01-01

    The effects of groundwater pumping on surface-water features were evaluated by use of a numerical groundwater model developed for a complex glacial-sediment aquifer in northeastern Framingham, Massachusetts, and parts of surrounding towns. The aquifer is composed of sand, gravel, silt, and clay glacial-fill sediments up to 270 feet thick over an irregular fractured bedrock surface. Surface-water bodies, including Cochituate Brook, the Sudbury River, Lake Cochituate, Dudley Pond, and adjoining wetlands, are in hydraulic connection with the aquifer and can be affected by groundwater withdrawals. Groundwater and surface-water interaction was simulated with MODFLOW-NWT under current conditions and a variety of hypothetical pumping conditions. Simulations of hypothetical pumping at reactivated water supply wells indicate that captured groundwater would decrease baseflow to the Sudbury River and induce recharge from Lake Cochituate. Under constant (steady-state) pumping, induced groundwater recharge from Lake Cochituate was equal to about 32 percent of the simulated pumping rate, and flow downstream in the Sudbury River decreased at the same rate as pumping. However, surface water responded quickly to pumping stresses. When pumping was simulated for 1 month and then stopped, streamflow depletions decreased by about 80 percent within 2 months and by about 90 percent within about 4 months. The fast surface water response to groundwater pumping offers the potential to substantially reduce streamflow depletions during periods of low flow, which are of greatest concern to the ecological integrity of the river. Results indicate that streamflow depletion during September, typically the month of lowest flow, can be reduced by 29 percent by lowering the maximum pumping rates to near zero during September. Lowering pumping rates for 3 months (July through September) reduces streamflow depletion during September by 79 percent as compared to constant pumping. These results

  2. When lithography meets self-assembly: a review of recent advances in the directed assembly of complex metal nanostructures on planar and textured surfaces

    Science.gov (United States)

    Hughes, Robert A.; Menumerov, Eredzhep; Neretina, Svetlana

    2017-07-01

    One of the foremost challenges in nanofabrication is the establishment of a processing science that integrates wafer-based materials, techniques, and devices with the extraordinary physicochemical properties accessible when materials are reduced to nanoscale dimensions. Such a merger would allow for exacting controls on nanostructure positioning, promote cooperative phenomenon between adjacent nanostructures and/or substrate materials, and allow for electrical contact to individual or groups of nanostructures. With neither self-assembly nor top-down lithographic processes being able to adequately meet this challenge, advancements have often relied on a hybrid strategy that utilizes lithographically-defined features to direct the assembly of nanostructures into organized patterns. While these so-called directed assembly techniques have proven viable, much of this effort has focused on the assembly of periodic arrays of spherical or near-spherical nanostructures comprised of a single element. Work directed toward the fabrication of more complex nanostructures, while still at a nascent stage, has nevertheless demonstrated the possibility of forming arrays of nanocubes, nanorods, nanoprisms, nanoshells, nanocages, nanoframes, core-shell structures, Janus structures, and various alloys on the substrate surface. In this topical review, we describe the progress made in the directed assembly of periodic arrays of these complex metal nanostructures on planar and textured substrates. The review is divided into three broad strategies reliant on: (i) the deterministic positioning of colloidal structures, (ii) the reorganization of deposited metal films at elevated temperatures, and (iii) liquid-phase chemistry practiced directly on the substrate surface. These strategies collectively utilize a broad range of techniques including capillary assembly, microcontact printing, chemical surface modulation, templated dewetting, nanoimprint lithography, and dip-pen nanolithography and

  3. Self-assembly of individually addressable complexes of C60 and phthalocyanines on a metal surface: Structural and electronic investigations

    Energy Technology Data Exchange (ETDEWEB)

    Samuely, Tomas [University of Basel (Switzerland); Liu, Shi-Xia; Haas, Marco; Decurtins, Silvio [University of Bern (Switzerland); Jung, Thomas [Paul-Scherrer-Institute (Switzerland); Stoehr, Meike [University of Groningen (Netherlands)

    2011-07-01

    A complex phase behavior was found for a specific phthalocyanine (Pc) derivative adsorbed on either Au(111) or Ag(111). The Pc molecule is symmetrically substituted with eight peripheral di-(tert-butyl)phenoxy (DTPO) groups. The pronounced ability of the DTPO groups to rotate, allows the molecule to adopt different conformations and hence to arrange itself in different ordered patterns. In particular, when all DTPO substituents are arranged above the plane of the Pc core (a bowl-like structure is formed), the interaction of the Pc core with the metal substrate is enabled. Moreover, for such an assembly the hosting properties for the adsorption of C{sub 60} were investigated. The C{sub 60} molecules adsorb at two clearly distinguishable positions on the predeposited Pc layer: they are in contact either with the metal substrate in between two adjacent Pc molecules or with the Pc core. For the latter case, the C{sub 60} is located directly above the pi-conjugated Pc core. Hence, the presented system combines the three following features: (i) the direct electronic interaction between donor and acceptor moieties, (ii) the formation by self-assembly, and (iii) thermal stability. Thereby, the direct investigation of a single donor-acceptor complex is enabled.

  4. Studies of ternary surface complexes at liquid-solid interfaces in seawater. 3: Comparative studies of the E(%)-pH curves and the diffuse reflectance IR spectra of the {alpha}-FeOOH-Cu(II)-tryptophan system

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zhengbin; Wang Wei; Liu Liansheng; Fu Youjun; Wu Zhijian [Ocean Univ. of Qingdao (China). Inst. of Marine Chemistry

    1997-06-01

    The E(%)-pH curves of the ternary surface complexes at liquid-solid interfaces in the simulated seawater system of {alpha}-FeOOH-Cu(II)-tryptophan were determined. The diffuse reflectance IR spectra of the species at the solid surfaces in the above ternary equilibration system were examined. The above two results were comparatively studied. It is shown that the coadsorption of Cu(II) and tryptophan on {alpha}0FeOOH surface results in the formation of the ternary surface complex. Cu(II) can promote the exchange adsorption of tryptophan on {alpha}-FeOOH surface. The diffuse reflectance IR spectra can give one some evidence for the structure of the ternary surface complex, and these results are in accordance with the results of the E(%)-pH curves.

  5. Study of the surface modification with oleic acid of nanosized HfO{sub 2} synthesized by the polymerized complex derived sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Ramos-Gonzalez, R., E-mail: rramos.phd@gmail.com [Centro de Investigacion en Quimica Aplicada, Blvd. Enrique Reyna Hermosillo No. 140, Saltillo, Coahuila 25250 (Mexico); Garcia-Cerda, L.A. [Centro de Investigacion en Quimica Aplicada, Blvd. Enrique Reyna Hermosillo No. 140, Saltillo, Coahuila 25250 (Mexico); Quevedo-Lopez, M.A. [University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080-3021 (United States)

    2012-06-01

    The synthesis of nanosized hafnium oxide by the polymerized complex derived sol-gel method is reported. The structural and morphological characterization of the HfO{sub 2} was carried out by X-ray diffraction and scanning electron microscopy. The surface of hafnium oxide nanoparticles was modified by capping with oleic acid. The nanoparticle surface area was measured by the gas adsorption technique in order to determine the minimal amount of oleic acid needed to obtain a uniform coverage of the hafnium oxide. The existence of organic layer can be confirmed by Fourier transform spectroscopy, solid state nuclear magnetic resonance spectroscopy, thermal gravimetric analysis and transmission electron microscopy. The FTIR and solid state NMR results reveal that oleic acid is chemisorbed as a carboxylate onto the HfO{sub 2} nanoparticle surface and confirm the formation of a monomolecular layer of oleic acid surrounding the HfO{sub 2}. The cover density of oleic acid on the HfO{sub 2} increases with the amount of oleic acid used to modify the nanoparticles and the surface properties of HfO{sub 2} nanoparticles modified with oleic acid change from hydrophilic to hydrophobic.

  6. In various protein complexes, disordered protomers have large per-residue surface areas and area of protein-, DNA- and RNA-binding interfaces.

    Science.gov (United States)

    Wu, Zhonghua; Hu, Gang; Yang, Jianyi; Peng, Zhenling; Uversky, Vladimir N; Kurgan, Lukasz

    2015-09-14

    We provide first large scale analysis of the peculiarities of surface areas of 5658 dissimilar (below 50% sequence similarity) proteins with known 3D-structures that bind to proteins, DNA or RNAs. We show here that area of the protein surface is highly correlated with the protein length. The size of the interface surface is only modestly correlated with the protein size, except for RNA-binding proteins where larger proteins are characterized by larger interfaces. Disordered proteins with disordered interfaces are characterized by significantly larger per-residue areas of their surfaces and interfaces when compared to the structured proteins. These result are applicable for proteins involved in interaction with DNA, RNA, and proteins and suggest that disordered proteins and binding regions are less compact and more likely to assume extended shape. We demonstrate that disordered protein binding residues in the interfaces of disordered proteins drive the increase in the per residue area of these interfaces. Our results can be used to predict in silico whether a given protomer from the DNA, RNA or protein complex is likely to be disordered in its unbound form.

  7. Can simulations of flux exchanges between the land surface and the atmosphere be improved by a more complex description of soil and plant processes?

    Science.gov (United States)

    Klein, Christian

    2013-04-01

    Can simulations of flux exchanges between the land surface and the atmosphere be improved by a more complex description of soil and plant processes? Christian Klein, Christian Biernath, Peter Hoffmann and Eckart Priesack Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Soil Ecology, Oberschleissheim, Germany christian.klein@helmholtz-muenchen.de, ++ 49 89 3187 3015 Recent studies show, that uncertainties in regional and global climate simulations are partly caused by inadequate descriptions of soil-plant-atmosphere. Therefore, we coupled the soil-plant model system Expert-N to the regional climate and weather forecast model WRF. Key features of the Expert-N model system are the simulation of water flow, heat transfer and solute transport in soils and the transpiration of grassland and forest stands. Particularly relevant for the improvement of regional weather forecast are simulations of the feedback between the land surface and atmosphere, which influences surface temperature, surface pressure and precipitation. The WRF model was modified to optionally select either the land surface model Expert-N or NOAH to simulate the exchange of water and energy fluxes between the land surface and the atmosphere for every single grid cell within the simulation domain. Where the standard land surface model NOAH interpolates monthly LAI input values to simulate interactions between plant and atmosphere Expert-N simulates a dynamic plant growth with respect to water and nutrient availability in the soil. In this way Expert-N can be applied to study the effect of dynamic vegetation growth simulation on regional climate simulation results. For model testing Expert-N was used with two different soil parameterizations. The first parametrization used the USGS soil texture classification and simplifies the soil profile to one horizon (similar to the NOAH model). The second parameterization is based on the German soil texture classification

  8. Surface complexation and precipitate geometry for aqueous Zn(II) sorption on ferrihydrite I: X-ray absorption extended fine structure spectroscopy analysis

    Science.gov (United States)

    Waychunas, G.A.; Fuller, C.C.; Davis, J.A.

    2002-01-01

    "Two-line" ferrihydrite samples precipitated and then exposed to a range of aqueous Zn solutions (10-5 to 10-3 M), and also coprecipitated in similar Zn solutions (pH 6.5), have been examined by Zn and Fe K-edge X-ray absorption spectroscopy. Typical Zn complexes on the surface have Zn-O distances of 1.97(0.2) A?? and coordination numbers of about 4.0(0.5), consistent with tetrahedral oxygen coordination. This contrasts with Zn-O distances of 2.11(.02) A?? and coordination numbers of 6 to 7 in the aqueous Zn solutions used in sample preparation. X-ray absorption extended fine structure spectroscopy (EXAFS) fits to the second shell of cation neighbors indicate as many as 4 Zn-Fe neighbors at 3.44(.04) A?? in coprecipitated samples, and about two Zn-Fe neighbors at the same distance in adsorption samples. In both sets of samples, the fitted coordination number of second shell cations decreases as sorption density increases, indicating changes in the number and type of available complexing sites or the onset of competitive precipitation processes. Comparison of our results with the possible geometries for surface complexes and precipitates suggests that the Zn sorption complexes are inner sphere and at lowest adsorption densities are bidentate, sharing apical oxygens with adjacent edge-sharing Fe(O,OH)6 octahedra. Coprecipitation samples have complexes with similar geometry, but these are polydentate, sharing apices with more than two adjacent edge-sharing Fe(O,OH)6 polyhedra. The results are inconsistent with Zn entering the ferrihydrite structure (i.e., solid solution formation) or formation of other Zn-Fe precipitates. The fitted Zn-Fe coordination numbers drop with increasing Zn density with a minimum of about 0.8(.2) at Zn/(Zn + Fe) of 0.08 or more. This change appears to be attributable to the onset of precipitation of zinc hydroxide polymers with mainly tetrahedral Zn coordination. At the highest loadings studied, the nature of the complexes changes further

  9. A Hirshfeld surface analysis, crystal structure and spectroscopic properties of new Zn(II) complex with N-aminoethylpiperazine ligand

    Science.gov (United States)

    El Glaoui, Maroua; El Glaoui, Maher; Jelsch, Christian; Aubert, Emmanuel; Lefebvre, Frédéric; Ben Nasr, Chérif

    2017-04-01

    A new organic-inorganic hybrid material, 1-amonioethylpiperazine-1, 4-diium tetrachloridozincate(II) chloride, (C6H18N3)[ZnCl4]Cl, has been synthesized and characterized by various physicochemical techniques including UV-visible absorption, Infra-Red (IR), Raman and NMR spectroscopies. The compound crystallizes in the monoclinic system and P21 space group with Z = 2 and the following unit cell dimensions: a = 7.1728 (6), b = 12.4160 (11), c = 8.0278 (7) Å, β = 97.513 (1)°, V = 708.80 (11) Å3. In this structure, the Zn2+ ion, surrounded by four chlorides, adopts a distorted tetrahedral coordination geometry. The structure of this compound consists of monomeric 1-amonioethylpiperazine-1, 4-diium trications and monomeric [ZnCl4]2- and Cl- anions. These entities are interconnected by means of hydrogen bonding contacts [Nsbnd H⋯Cl, Csbnd H⋯Cl], forming a three-dimensional network. Intermolecular interactions were investigated by Hirshfeld surfaces. More than three quarters of the interaction surface in the crystal packing is constituted by attractive and favored H⋯Cl hydrogen bonds. The 13C and 15N CP-MAS NMR spectra are discussed and the vibrational absorption bands were identified by infrared and Raman spectroscopy.

  10. Mycobacterium icosiumassiliensis sp. nov., a New Member in the Mycobacterium terrae Complex Isolated from Surface Water in Algeria.

    Science.gov (United States)

    Djouadi, Lydia N; Levasseur, Anthony; Khalil, Jacques Bou; Blanc-Taileur, Caroline; Asmar, Shady; Ghiloubi, Wassila; Natèche, Farida; Drancourt, Michel

    2016-08-01

    An acid-fast, rapidly growing, rod-shaped microorganism designated 8WA6 was isolated from a lake in Algiers, Algeria. The lake water was characterized by a temperature of 18 °C, a pH of 7.82, a copper concentration of 8.6 µg/L, and a cadmium concentration of 0.6 µg/L. First-line molecular identification confirmed the 8WA6 isolate to be a member of the Mycobacterium terrae complex, sharing 99.4 % 16S rRNA gene sequence similarity with M. arupense AR-30097, 98.2 % partial hsp65 gene sequence similarity with M. terrae 28K766, and 97.1 % partial rpoB gene sequence similarity with Mycobacterium sp. FI-05396. Its 4.89-Mb genome exhibits a 66.8 GC % and an average nucleotide identity of 64.5 % with M. tuberculosis, 70.5 % with M. arupense, and 75 % with M. asiaticum. In the M. terrae complex, Mycobacterium 8WA6 was unique in exhibiting growth at 42 °C, negative reaction for nitrate reduction, urease activity and Tween 80 hydrolysis, and a positive reaction for α-glucosidase and β-glucosidase. Its protein profile determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry revealed a unique spectrum similar to M. arupense and M. terrae, exhibiting eleven specific peaks at 3787.791, 4578.019, 6349.630, 6855.638, 7202.310, 8149.608, 8775.257, 10,224.588, 10,484.116, 12,226.379, and 12,636.871 m/z. Minimal inhibitory concentrations (MIC) for antibiotics, determined by microdilution, indicated a broad spectrum resistance, except for rifabutin (MIC, 0.5 g/L) and cefoxitin (MIC, 16 g/L). We concluded that the 8WA6 isolate is a representative isolate of a previously undescribed species in the M. terrae complex, which was named M. icosiumassiliensis sp. nov. with strain 8WA6 (Collection de Souches de l'Unité des Rickettsies, CSUR P1561, Deutsche Sammlung von Mikroorganismen und Zellkulturen, DSM 100711) as the type strain.

  11. Complex surface analytical investigations on hydrogen absorption and desorption processes of a TiMn2-based alloy.

    Science.gov (United States)

    Schülke, Mark; Kiss, Gábor; Paulus, Hubert; Lammers, Martin; Ramachandran, Vaidyanath; Sankaran, Kannan; Müller, Karl-Heinz

    2009-04-01

    Metal hydrides are one of the most promising technologies in the field of hydrogen storage due to their high volumetric storage density. Important reaction steps take place at the very surface of the solid during hydrogen absorption. Since these reaction steps are drastically influenced by the properties and potential contamination of the solid, it is very important to understand the characteristics of the surface, and a variety of analytical methods are required to achieve this. In this work, a TiMn(2)-type metal hydride alloy is investigated by means of high-pressure activation measurements, X-ray photoelectron spectroscopy (XPS), secondary neutral mass spectrometry (SNMS) and thermal desorption mass spectrometry (TDMS). In particular, TDMS is an analytical tool that, in contrast to SIMS or SNMS, allows the hydrogen content in a metal to be quantified. Furthermore, it allows the activation energy for desorption to be determined from TDMS profiles; the method used to achieve this is presented here in detail. In the results section, it is shown that the oxide layer formed during manufacture and long-term storage prevents any hydrogen from being absorbed, and so an activation process is required. XPS measurements show the oxide states of the main alloy elements, and a layer 18 nm thick is determined via SNMS. Furthermore, defined oxide layers are produced and characterized in UHV using XPS. The influence of these thin oxide layers on the hydrogen sorption process is examined using TDMS. Finally, the activation energy of desorption is determined for the investigated alloy using the method presented here, and values of 46 kJ/mol for hydrogen sorbed in UHV and 103 kJ/mol for hydrogen originating from the manufacturing process are obtained.

  12. Surface complexation modeling for predicting solid phase arsenic concentrations in the sediments of the Mississippi River Valley alluvial aquifer, Arkansas, USA

    Science.gov (United States)

    Sharif, M.S.U.; Davis, R.K.; Steele, K.F.; Kim, B.; Hays, P.D.; Kresse, T.M.; Fazio, J.A.

    2011-01-01

    The potential health impact of As in drinking water supply systems in the Mississippi River Valley alluvial aquifer in the state of Arkansas, USA is significant. In this context it is important to understand the occurrence, distribution and mobilization of As in the Mississippi River Valley alluvial aquifer. Application of surface complexation models (SCMs) to predict the sorption behavior of As and hydrous Fe oxides (HFO) in the laboratory has increased in the last decade. However, the application of SCMs to predict the sorption of As in natural sediments has not often been reported, and such applications are greatly constrained by the lack of site-specific model parameters. Attempts have been made to use SCMs considering a component additivity (CA) approach which accounts for relative abundances of pure phases in natural sediments, followed by the addition of SCM parameters individually for each phase. Although few reliable and internally consistent sorption databases related to HFO exist, the use of SCMs using laboratory-derived sorption databases to predict the mobility of As in natural sediments has increased. This study is an attempt to evaluate the ability of the SCMs using the geochemical code PHREEQC to predict solid phase As in the sediments of the Mississippi River Valley alluvial aquifer in Arkansas. The SCM option of the double-layer model (DLM) was simulated using ferrihydrite and goethite as sorbents quantified from chemical extractions, calculated surface-site densities, published surface properties, and published laboratory-derived sorption constants for the sorbents. The model results are satisfactory for shallow wells (10.6. m below ground surface), where the redox condition is relatively oxic or mildly suboxic. However, for the deep alluvial aquifer (21-36.6. m below ground surface) where the redox condition is suboxic to anoxic, the model results are unsatisfactory. ?? 2011 Elsevier Ltd.

  13. The effect of near-infrared laser beam on the surface modification of metal complex based on 3D laser scanning system

    Science.gov (United States)

    Zhao, Mali; Liu, Tiegen; Jiang, Junfeng; Wang, Meng

    2014-11-01

    High-precision 3-dimensional metallization is difficult to realize in specific nonmetallic areas by using the traditional methods such as wet-chemical and mechanical methods because of the disadvantage that usually they cannot achieve selective modification. In this paper, 3-dimensional laser scanning system was applied to achieve the modification of specific regions of the sample surface. In 3-dimensional laser scanning system, the laser beam, after going through dynamic focusing system, was reflected by galvanometers and then focused by f-theta lens on the sample surface. The changes in surface characteristics of the blends of polycarbonate and acrylonitrile butadiene styrene copolymers (PC/ABS) mixed with Cu-Cr complex by the laser irradiation with the wavelength of 1064nm were investigated. Through analysis it was found that the smooth surface of the original samples was changed to a micro-hole structure accompanied by an increased surface roughness as well as an increased water contact angle. The chemical composition percentage had changed and the metal components of copper and chromium were detected after the laser irradiation. The irradiated areas were degraded into organic ligand fragments, volatile gas and reducing metal ions of copper and chromium. Besides, the thickness of the deposited metal layer and the adhesive force between the metal layer and the substrate after electroless plating varied according to the laser parameters such as frequency and scanning speed. As shown in the experiment, the thickness of deposited copper layer exceeded 11μm and the deposited nickel layer exceeded 2μm respectively.

  14. Uncovering the stoichiometry of Pyrococcus furiosus RNase P, a multi-subunit catalytic ribonucleoprotein complex, by surface-induced dissociation and ion mobility mass spectrometry.

    Science.gov (United States)

    Ma, Xin; Lai, Lien B; Lai, Stella M; Tanimoto, Akiko; Foster, Mark P; Wysocki, Vicki H; Gopalan, Venkat

    2014-10-20

    We demonstrate that surface-induced dissociation (SID) coupled with ion mobility mass spectrometry (IM-MS) is a powerful tool for determining the stoichiometry of a multi-subunit ribonucleoprotein (RNP) complex assembled in a solution containing Mg(2+). We investigated Pyrococcus furiosus (Pfu) RNase P, an archaeal RNP that catalyzes tRNA 5' maturation. Previous step-wise, Mg(2+)-dependent reconstitutions of Pfu RNase P with its catalytic RNA subunit and two interacting protein cofactor pairs (RPP21⋅RPP29 and POP5⋅RPP30) revealed functional RNP intermediates en route to the RNase P enzyme, but provided no information on subunit stoichiometry. Our native MS studies with the proteins showed RPP21⋅RPP29 and (POP5⋅RPP30)2 complexes, but indicated a 1:1 composition for all subunits when either one or both protein complexes bind the cognate RNA. These results highlight the utility of SID and IM-MS in resolving conformational heterogeneity and yielding insights on RNP assembly.

  15. Resisting the seduction of "ethics creep": using Foucault to surface complexity and contradiction in research ethics review.

    Science.gov (United States)

    Guta, Adrian; Nixon, Stephanie A; Wilson, Michael G

    2013-12-01

    In this paper we examine "ethics creep", a concept developed by Haggerty (2004) to account for the increasing bureaucratization of research ethics boards and institutional review boards (REB/IRBs) and the expanding reach of ethics review. We start with an overview of the recent surge of academic interest in ethics creep and similar arguments about the prohibitive effect of ethics review. We then introduce elements of Michel Foucault's theoretical framework which are used to inform our analysis of empirical data drawn from a multi-phase study exploring the accessibility of community-engaged research within existing ethics review structures in Canada. First, we present how ethics creep emerged both explicitly and implicitly in our data. We then present data that demonstrate how REB/IRBs are experiencing their own form of regulation. Finally, we present data that situate ethics review alongside other trends affecting the academy. Our results show that ethics review is growing in some ways while simultaneously being constrained in others. Drawing on Foucauldian theory we reframe ethics creep as a repressive hypothesis which belies the complexity of the phenomenon it purports to explain. Our discussion complicates ethics creep by proposing an understanding of REB/IRBs that locates them at the intersection of various neoliberal discourses about the role of science, ethics, and knowledge production.

  16. Combine umbrella sampling with integrated tempering method for efficient and accurate calculation of free energy changes of complex energy surface.

    Science.gov (United States)

    Yang, Mingjun; Yang, Lijiang; Gao, Yiqin; Hu, Hao

    2014-07-28

    Umbrella sampling is an efficient method for the calculation of free energy changes of a system along well-defined reaction coordinates. However, when there exist multiple parallel channels along the reaction coordinate or hidden barriers in directions perpendicular to the reaction coordinate, it is difficult for conventional umbrella sampling to reach convergent sampling within limited simulation time. Here, we propose an approach to combine umbrella sampling with the integrated tempering sampling method. The umbrella sampling method is applied to chemically more relevant degrees of freedom that possess significant barriers. The integrated tempering sampling method is used to facilitate the sampling of other degrees of freedom which may possess statistically non-negligible barriers. The combined method is applied to two model systems, butane and ACE-NME molecules, and shows significantly improved sampling efficiencies as compared to standalone conventional umbrella sampling or integrated tempering sampling approaches. Further analyses suggest that the enhanced performance of the new method come from the complemented advantages of umbrella sampling with a well-defined reaction coordinate and integrated tempering sampling in orthogonal space. Therefore, the combined approach could be useful in the simulation of biomolecular processes, which often involves sampling of complex rugged energy landscapes.

  17. Hansenula polymorpha Pmt4p Plays Critical Roles in O-Mannosylation of Surface Membrane Proteins and Participates in Heteromeric Complex Formation.

    Directory of Open Access Journals (Sweden)

    Hyunah Kim

    Full Text Available O-mannosylation, the addition of mannose to serine and threonine residues of secretory proteins, is a highly conserved post-translational modification found in organisms ranging from bacteria to humans. Here, we report the functional and molecular characterization of the HpPMT4 gene encoding a protein O-mannosyltransferase in the thermotolerant methylotrophic yeast Hansenula polymorpha, an emerging host for the production of therapeutic recombinant proteins. Compared to the deletion of HpPMT1, deletion of another major PMT gene, HpPMT4, resulted in more increased sensitivity to the antibiotic hygromycin B, caffeine, and osmotic stresses, but did not affect the thermotolerance of H. polymorpha. Notably, the deletion of HpPMT4 generated severe defects in glycosylation of the surface sensor proteins HpWsc1p and HpMid2p, with marginal effects on secreted glycoproteins such as chitinase and HpYps1p lacking a GPI anchor. However, despite the severely impaired mannosylation of surface sensor proteins in the Hppmt4∆ mutant, the phosphorylation of HpMpk1p and HpHog1p still showed a high increase upon treatment with cell wall disturbing agents or high concentrations of salts. The conditional Hppmt1pmt4∆ double mutant strains displayed severely impaired growth, enlarged cell size, and aberrant cell separation, implying that the loss of HpPMT4 function might be lethal to cells in the absence of HpPmt1p. Moreover, the HpPmt4 protein was found to form not only a homomeric complex but also a heteromeric complex with either HpPmt1p or HpPmt2p. Altogether, our results support the function of HpPmt4p as a key player in O-mannosylation of cell surface proteins and its participation in the formation of heterodimers with other PMT members, besides homodimer formation, in H. polymorpha.

  18. Constructing an Interpolated Potential Energy Surface of a Large Molecule: A Case Study with Bacteriochlorophyll a Model in the Fenna-Matthews-Olson Complex.

    Science.gov (United States)

    Kim, Chang Woo; Rhee, Young Min

    2016-11-08

    Constructing a reliable potential energy surface (PES) is a key step toward computationally studying the chemical dynamics of any molecular system. The interpolation scheme is a useful tool that can closely follow the accuracy of quantum chemical means at a dramatically reduced computational cost. However, applying interpolation to building a PES of a large molecule is not a straightforward black-box approach, as it frequently encounters practical difficulties associated with its large dimensionality. Here, we present detailed courses of applying interpolation toward building a PES of a large chromophore molecule. We take the example of S0 and S1 electronic states of bacteriochlorophyll a (BChla) molecules in the Fenna-Matthews-Olson light harvesting complex. With a reduced model molecule that bears BChla's main π-conjugated ring, various practical approaches are designed for improving the PES quality in a stable manner and for fine-tuning the final surface such that the surface can be adopted for long time molecular dynamics simulations. Combined with parallel implementation, we show that interpolated mechanics/molecular mechanics (IM/MM) simulations of the entire complex in the nanosecond time scale can be conducted readily without any practical issues. With 1500 interpolation data points for each chromophore unit, the PES error relative to the reference quantum chemical calculation is found to be ∼0.15 eV in the thermally accessible region of the conformational space, together with ∼0.01 eV error in S0 - S1 transition energies. The performance issue related to the use of a large interpolation database within the framework of our parallel routines is also discussed.

  19. The origin of the strong interfacial charge-transfer absorption in the surface complex between TiO2 and dicyanomethylene compounds.

    Science.gov (United States)

    Jono, Ryota; Fujisawa, Jun-ichi; Segawa, Hiroshi; Yamashita, Koichi

    2013-11-14

    Interfacial charge transfer transitions between organic and inorganic materials are expected to be a potential photoinduced charge separation mechanism for photoenergy conversions. Recently, we reported that the hybrid material formed from TiO2 nanoparticles and an organic electron acceptor, 7,7,8,8-tetracyanoquinodimethane (TCNQ), shows strong interfacial charge transfer absorption in the visible region. In this work, we have theoretically studied the structure, and electronic and absorption properties in order to clarify the formation mechanism and the origin of the strong interfacial charge transfer absorption. Density functional theory (DFT) calculations employing an anatase Ti14O28H2(OH)2(H2O)2 nano-cluster unraveled that the surface complex is formed by a nucleophilic addition reaction between a surface hydroxyl group of TiO2 and the carbon atom of the methylene moiety in TCNQ with the drastic changes in the structure and electronic properties of TCNQ. In the formation process, owing to the high electron affinity of TCNQ, a negative charge of the surface oxygen atom is transferred to the TCNQ moiety. This leads to a significant electronic hybridization between TiO2 and TCNQ, which is the origin of interfacial charge transfer transitions.

  20. Induction of cell self-organization on weakly positively charged surfaces prepared by the deposition of polyion complex nanoparticles of thermoresponsive, zwitterionic copolymers.

    Science.gov (United States)

    Iwai, Ryosuke; Haruki, Ryota; Nemoto, Yasushi; Nakayama, Yasuhide

    2017-07-01

    We have developed inducible cell self-organization through weakly positively charged culture surfaces. In this study, a thermoresponsive and zwitterionic copolymer comprised of N,N-dimethylaminoethyl methacrylate (DMAEMA) and methacrylic acid (MA) (PDMAEMA-co-PMA; Mn: ∼9.7 × 10(4) g/mol; PDMAEMA/PMA ratio: 10) was designed for inducing cell self-organization. The copolymer formed single polymer-derived polyion complex (sPIC) nanoparticles following dissolution in an aqueous solution. The sPIC nanoparticles had a positive charge (ca. 25 mV). Self-organization occurred in adipose-derived vascular stromal cell monolayers cultivated on sPIC-deposited surfaces. There were dramatic morphological changes of these cells with the formation of capillary-like networks and single-cell aggregates with little cytotoxicity. This was a significant improvement compared with cells grown on previously developed surfaces deposited with PIC, a mixture of PDMAEMA and plasmid DNA. Thus, sPICs of PDMAEMA-co-PMA may allow for the accurate evaluation of a variety of cell behaviors with less cytotoxicity, and may facilitate additional potential medical applications such as cell-based therapy and drug discovery. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1009-1015, 2017. © 2016 Wiley Periodicals, Inc.

  1. Quantitative analysis of surface deformation and ductile flow in complex analogue geodynamic models based on PIV method.

    Science.gov (United States)

    Krýza, Ondřej; Lexa, Ondrej; Závada, Prokop; Schulmann, Karel; Gapais, Denis; Cosgrove, John

    2017-04-01

    Recently, a PIV (particle image velocimetry) analysis method is optical method abundantly used in many technical branches where material flow visualization and quantification is important. Typical examples are studies of liquid flow through complex channel system, gas spreading or combustion problematics. In our current research we used this method for investigation of two types of complex analogue geodynamic and tectonic experiments. First class of experiments is aimed to model large-scale oroclinal buckling as an analogue of late Paleozoic to early Mesozoic evolution of Central Asian Orogenic Belt (CAOB) resulting from nortward drift of the North-China craton towards the Siberian craton. Here we studied relationship between lower crustal and lithospheric mantle flows and upper crustal deformation respectively. A second class of experiments is focused to more general study of a lower crustal flow in indentation systems that represent a major component of some large hot orogens (e.g. Bohemian massif). The most of simulations in both cases shows a strong dependency of a brittle structures shape, that are situated in upper crust, on folding style of a middle and lower ductile layers which is influenced by rheological, geometrical and thermal conditions of different parts across shortened domain. The purpose of PIV application is to quantify material redistribution in critical domains of the model. The derivation of flow direction and calculation of strain-rate and total displacement field in analogue experiments is generally difficult and time-expensive or often performed only on a base of visual evaluations. PIV method operates with set of images, where small tracer particles are seeded within modeled domain and are assumed to faithfully follow the material flow. On base of pixel coordinates estimation the material displacement field, velocity field, strain-rate, vorticity, tortuosity etc. are calculated. In our experiments we used velocity field divergence to

  2. Extreme heterogeneity of land surface in spring inducing highly complex micrometeorological flow features and heat exchange processes over partly snow covered areas

    Science.gov (United States)

    Mott, Rebecca; Schlögl, Sebastian; Dirks, Lisa; Lehning, Michael

    2017-04-01

    The melting mountain snow cover in spring typically changes from a continuous snow cover to a mosaic of patches of snow and bare ground inducing an extreme heterogeneity of the land surface. Energy balance models typically assume a continuous snow cover, neglecting the complex interaction between the atmospheric boundary layer and the strongly variable surface. We experimentally investigated the small-scale boundary layer dynamics over snow patches and their effect on the energy balance at the snow surface. A comprehensive measurement campaign, the Dischma Experiment, was conducted during three entire ablation periods in spring 2014, 2015 and 2016. The aim of this project is to investigate the boundary layer development and the energy exchange over a melting snow cover with a gradually decreasing snow cover fraction. For this purpose, two measurement towers equipped with five to six ultrasonic anemometers were installed over a long-lasting snow patch. Furthermore, temporally and spatially high resolution ablation rates and snow surface temperatures were determined with a terrestrial laser scanner and an Infrared camera. This data set allows us to relate the spatial patterns of ablation rates and snow surface temperatures to boundary layer dynamics and the changing snow cover fraction. Experimental data reveal that wind conditions, snow cover distribution, local wind fetch distance and topographical curvature control the near-surface boundary layer characteristics and heat exchange processes over snow. The strong heterogeneity of land surface induced by the patchy snow cover caused a high spatial and temporal variability of snow surface temperature and snow melt patterns. Small scale flow features, such as katabatic flows or wind sheltering can be shown to strongly affect the temporal evolution of snow surface patterns. Furthermore, turbulence data reveal a strong correlation of turbulent heat exchange over melting snow with the occurrence of internal thermal

  3. Efficient biological conversion of carbon monoxide (CO) to carbon dioxide (CO2) and for utilization in bioplastic production by Ralstonia eutropha through the display of an enzyme complex on the cell surface.

    Science.gov (United States)

    Hyeon, Jeong Eun; Kim, Seung Wook; Park, Chulhwan; Han, Sung Ok

    2015-06-25

    An enzyme complex for biological conversion of CO to CO2 was anchored on the cell surface of the CO2-utilizing Ralstonia eutropha and successfully resulted in a 3.3-fold increase in conversion efficiency. These results suggest that this complexed system may be a promising strategy for CO2 utilization as a biological tool for the production of bioplastics.

  4. Lactobacillus plantarum gene clusters encoding putative cell-surface protein complexes for carbohydrate utilization are conserved in specific gram-positive bacteria

    Directory of Open Access Journals (Sweden)

    Muscariello Lidia

    2006-05-01

    D proteins form cell-surface protein complexes and play a role in carbon source acquisition. Primary occurrence in plant-associated gram-positive bacteria suggests a possible role in degradation and utilization of plant oligo- or poly-saccharides.

  5. Complex Hierarchical Structures and Hydrophobicity of Butterfly Wing Surface%蝴蝶翅表面的多级复合结构和疏水性

    Institute of Scientific and Technical Information of China (English)

    房岩; 韩德复; 毕语涵; 孙刚

    2014-01-01

    The complex hierarchical structures and hydrophobicity of wing surface of 22 butterfly species were investigated by means of a scanning electron microscopy and a contact angle measuring system. The primary structure is micrometric scale. The density of scale is 101~280 ind. /mm2 , and the length, width, and spacing of scale are 65~135 μm, 35~85 μm, and 48~112 μm, respectively. The secondary structure is submicrometric vertical gibbosities and horizontal links on scale surface. The tertiary structure is nano-protuber-ances on vertical gibbosities and horizontal links. Butterfly wing surface has contact angles of distilled water as high as 138. 2o~158. 5o, belonging to natural hydrophobic surface, which is the coupling effect of chemical composition and microstructure on the wing surface. Butterfly wing surface may provide bio-template for fabrication of novel biomimetic material with self-cleaning property.%使用扫描电镜和视频光学接触角测量仪研究了22种蝴蝶翅表面的多级复合结构和疏水性。一级结构为微米级鳞片,鳞片密度为101~280个/mm2,长65~135滋m,宽35~85滋m,间距48~112滋m。二级结构为鳞片表面的亚微米级纵肋和横向连接。三级结构为纵肋和横向连接上的纳米级突起。蝴蝶翅表面的蒸馏水接触角为138.2º~158.5º,属于天然疏水表面,这是翅表面化学组成与微观结构协同作用的结果。蝴蝶翅表面可为新型仿生自清洁材料的制备提供生物模板。

  6. 复杂形状海洋浮体水动力系数计算%Calculation of Hydrodynamic Coefficients of Floating Body with Complex Wetted Surface

    Institute of Scientific and Technical Information of China (English)

    任慧龙; 刘文玺

    2008-01-01

    Mesh generation is the key step of hydrodynamic calculation.A method of mesh generation is presented for floating bodies with complex wetted surface.For the floating body with complex bow and stem,the molded line reconstruction method is adopted to generate the section lines on the bow and on the stern which are necessary to construct the wetted surface,and it Can raise efficiency greatly that the intersection lines of intersection structures are obtained by the way of combining modelingtool and NURBS technology;then the patch representation method is adopted in generating the mesh of wetted surface and interior free surface,and the velocity potentials on them aye expressed separately,on basis of which the irregular frequency effect is dealt with in the calculation of hydrodynamic coefficients.The results show that the above methods are fit for the calculation of hydrodynamic coefficients.%网格划分是水动力计算的关键环节,文中针对复杂形状海洋浮体提出了一种湿表面网格划分方法.对于有复杂首尾结构的浮体,用型线重构的方式在首尾生成曲面构成所需要的截面线,将通用建模工具和NURBS曲线拟合相结合,生成相贯结构的相交线;然后,用分片法生成浮体湿表面及内自由面网格,并独立表达各自的速度势以处理不规则频率现象,进而进行水动力系数计算.计算结果表明,上述处理方式很适合复杂形状海洋浮体水动力系数的计算.

  7. [(≢SiO)TaVCl2Me2]: A well-defined silica-supported tantalum(V) surface complex as catalyst precursor for the selective cocatalyst-free trimerization of ethylene

    KAUST Repository

    Chen, Yin

    2012-10-22

    On the surface of it: In the absence of co-catalyst, a well-defined silica-supported surface organometallic complex [(≢SiO)Ta VCl2Me2] selectively catalyzes the oligomerization of ethylene. The use of surface organometallic species allows three different pathways to be determined for the reduction of TaV to TaIII species under pressure of ethylene. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. A Hirshfeld surface analysis, crystal structure and physicochemical studies of a new Cd(II) complex with the 2-amino-4-methylpyrimidine ligand

    Science.gov (United States)

    Klai, Kacem; Kaabi, Kamel; Kaminsky, Werner; Jelsch, Christian; Lefebvre, Frédéric; Ben Nasr, Cherif

    2017-01-01

    A new Cd(II) complex with the monodentate ligand 2-amino-4-methylpyrimidine, [Cd(NO3)2(C5N3H7)2(H2O)2], has been prepared and characterized by single crystal X-ray diffraction, elemental analysis, CP-MAS NMR and IR spectroscopy. The basic coordination patterns of the 2-amino-4-methylpyrimidine coordinated metal cations are slightly distorted octahedra in this compound. The crystal structure is characterized by CdN2O4 octahedra interconnected via O-H…O and O-H…N hydrogen bonds to form layers parallel to the (b, c) plane. The crystal structure is stabilized by sets of hydrogen bonds, one of which is trifurcated. Intermolecular interactions were investigated by Hirshfeld surfaces. The 13C and 15N CP-MAS NMR spectra are discussed and the vibrational absorption bands were identified by infrared spectroscopy. Electronic properties such as HOMO and LUMO energies were derived.

  9. Molecular structure, natural bond analysis, vibrational and electronic spectra, surface enhanced Raman scattering and Mulliken atomic charges of the normal modes of [Mn(DDTC)2] complex

    Science.gov (United States)

    Téllez S., Claudio A.; Costa, Anilton C.; Mondragón, M. A.; Ferreira, Glaucio B.; Versiane, O.; Rangel, J. L.; Lima, G. Müller; Martin, A. A.

    2016-12-01

    Theoretical and experimental bands have been assigned for the Fourier Transform Infrared and Raman spectra of the bis(diethyldithiocarbamate)Mn(II) complex, [Mn(DDTC)2]. The calculations have been based on the DFT/B3LYP method, second derivative spectra and band deconvolution analysis. The UV-vis experimental spectra were measured in acetonitrile solution, and the calculated electronic spectrum was obtained using the TD/B3LYP method with 6-311G(d, p) basis set for all atoms. Charge transfer bands and those d-d spin forbidden were assigned in the UV-vis spectrum. The natural bond orbital analysis was carried out using the DFT/B3LYP method and the Mn(II) hybridization leading to the planar geometry of the framework was discussed. Surface enhanced Raman scattering (SERS) was also performed. Mulliken charges of the normal modes were obtained and related to the SERS enhanced bands.

  10. Study of Methods to Build Drawing Features on Complex Curved Surface%复杂曲面上构建图样特征的方法研究

    Institute of Scientific and Technical Information of China (English)

    王睿

    2012-01-01

    基于CAXA制造工程师软件中线面映射的功能,从实际应用出发,探讨了在复杂曲面上构建图样特征的方法,以便为在复杂曲面上加工图样打下基础,为后续刀具轨迹的生成做好准备。%Based on the function of line side mapping in the software of CAM manufacturing engineers, this paper starts from reality, and discusses the methods for building drawing feature on complex curved surface, so that it can lay the basis for processing drawmg g& prepared for the generation of the subsequent tool path.

  11. Immobilized molybdenum-thiosemicarbazide Schiff base complex on the surface of magnetite nanoparticles as a new nanocatalyst for the epoxidation of olefins

    Science.gov (United States)

    Mohammadikish, M.; Masteri-Farahani, M.; Mahdavi, S.

    2014-03-01

    In this work, a new magnetically recoverable nanocatalyst was developed by immobilization of thiosemicarbazide ligand on the surface of silica coated magnetite nanoparticles (SCMNPs) through Schiff base condensation and followed complexation with MoO2(acac)2. Characterization of the prepared nanocatalyst was performed with different physicochemical methods such as Fourier transform infrared (FT-IR) and atomic absorption spectroscopies, X-ray diffraction (XRD), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), field-emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The prepared catalyst catalyzed the epoxidation of olefins and allyl alcohols with tert-butyl hydroperoxide (TBHP) and cumene hydroperoxide (CHP) quantitatively with excellent selectivity toward the corresponding epoxides under mild reaction conditions.

  12. Kinetics of oxidation of an organic amine with a Cr(V) salen complex in homogeneous aqueous solution and on the surface of mesoporous silica.

    Science.gov (United States)

    Szajna-Fuller, Ewa; Huang, Yulin; Rapp, Jennifer L; Chaka, Gezahegn; Lin, Victor S Y; Pruski, Marek; Bakac, Andreja

    2009-05-07

    A comparative study of catalytic activity under homogeneous and heterogeneous conditions was carried out using the (salen)Cr(III)-catalyzed oxidation of tetramethylbenzidine (TMB) with iodosobenzene as a model reaction. Amine-functionalized mesoporous silica nanoparticles (MSN) were synthesized in a co-condensation reaction and functionalized with salen via a covalent Si-C bond. A Cr(III) complex of this supported ligand, MSN-(salen)Cr(III), was prepared and characterized. Data from powder XRD, BET isotherms and BJH pore size distribution all showed that MSN-(salen)Cr(III) still had the typical MSN high surface area, narrow pore size distribution, and ordered hexagonal pore structure, which were further confirmed by transmission electron microscopy (TEM) images. (13)C and (29)Si solid-state NMR data provided structural information about the catalyst and verified successful functionalization of the salen ligand and coordination to Cr(III). No unreacted salen or Cr(III) were observed. The loadings of salen and salen-Cr(III) complex were determined via TGA and EDX, respectively. Both measurements indicated that approximately 0.5 mmol/g of catalyst was loaded on the surface of MSN. The oxidation of TMB with iodosobenzene using MSN-(salen)Cr(III) as a heterogeneous catalyst exhibited both similarities and differences with the analogous homogeneous reaction using (salen)Cr(III)(H(2)O)(+) as a catalyst in aqueous acetonitrile. In the presence of 0.10 M HClO(4), the two catalytic reactions proceeded at similar rates and generated the doubly oxidized product TMB(2+). In the absence of acid, the radical cation TMB (+) was produced. The kinetics of the heterogeneous reaction in the absence of added acid responded to concentrations of all three reagents, i.e. (salen)Cr(III), TMB, and PhIO.

  13. Calculation of the structure, potential energy surface, vibrational dynamics, and electric dipole properties for the Xe:HI van der Waals complex.

    Science.gov (United States)

    Preller, M; Grunenberg, J; Bulychev, V P; Bulanin, M O

    2011-05-07

    We report the structure and spectroscopic characteristics for the Xe:HI van der Waals binary isomers determined from variational solutions of two-dimensional and three-dimensional (3D) vibrational Schrödinger equations. The solutions are based on a potential energy surface computed at the coupled-cluster level of theory including single and double excitations and a non-iterative perturbation treatment of triple excitations [CCSD(T)]. The dipole moment surface was calculated using quadratic configuration interaction (QCISD). The global potential minimum is shown to be located at the anti-hydrogen-bonded Xe-IH isomer, 21 cm(-1) below the secondary local minimum associated with the hydrogen-bonded Xe-HI isomeric form. The dissociation energy from the global minimum is 245.9 cm(-1). 3D Schrödinger equations are solved for the rotational quantum numbers J = k = 0, 1, and 2, without invoking an adiabatic separation of high- and low-frequency degrees of freedom. The vibrational ground state resides in the Xe-HI potential well, while the first excited state, 8.59 cm(-1) above the ground, occupies the Xe-IH well. We find that intra-complex dynamics exhibits a sudden transformation upon increase of the r(HI) bond length, accompanied by abrupt changes in the geometric and dipole parameters. A similar chaotic behavior is predicted to occur for Xe:DI at a shorter r(DI) bond length, which implies stronger coupling between low- and high-frequency motions in the heavier complex. Our calculations confirm a strong enhancement for the r(HI) stretch fundamental and a significant weakening for the first overtone vibrational transitions in Xe:HI, as compared to those in the free HI molecule. A qualitative explanation of this, earlier experimentally detected effect is suggested.

  14. Kinetic Isotope Effects as a Probe for the Protonolysis Mechanism of Alkylmetal Complexes: VTST/MT Calculations Based on DFT Potential Energy Surfaces.

    Science.gov (United States)

    Mai, Binh Khanh; Kim, Yongho

    2016-10-03

    Protonolysis by platinum or palladium complexes has been extensively studied because it is the microscopic reverse of the C-H bond activation reaction. The protonolysis of (COD)Pt(II)Me2, which exhibits abnormally large kinetic isotope effects (KIEs), is proposed to occur via a concerted pathway (SE2 mechanism) with large tunneling. However, further investigation of KIEs for the protonolysis of ZnMe2 and others led to a conclusion that there is no noticeable correlation between the mechanism and magnitude of KIE. In this study, we demonstrated that variational transition state theory including multidimensional tunneling (VTST/MT) could accurately predict KIEs and Arrhenius parameters of the protonolysis of alkylmetal complexes based on the potential energy surfaces generated by density functional theory. The predicted KIEs, Ea(D) - Ea(H) values, and AH/AD ratios for the protonolysis of (COD)Pt(II)Me2 and Zn(II)Me2 by TFA agreed very well with experimental values. The protonolysis of ZnMe2 with the concerted pathway has a very flat potential energy surface, which produces a very small tunneling effect and therefore a small KIE. The predicted KIE for the stepwise protonolysis (SE(ox) mechanism) of (COD)Pt(II)Me2 was much smaller than that of the concerted pathway, but greater than the KIE of the concerted protonolysis of ZnMe2. A large KIE, which entails a significant tunneling effect, could be used as an experimental probe of the concerted pathway. However, a normal or small KIE should not be used as an indicator of the stepwise mechanism, and the interplay between experiments and reliable theory including tunneling would be essential to uncover the mechanism correctly.

  15. Factors affecting the electrochemical regeneration of NADH by (2,2'-bipyridyl) (pentamethylcyclopentadienyl)-rhodium complexes: impact on their immobilization onto electrode surfaces.

    Science.gov (United States)

    Walcarius, Alain; Nasraoui, Rihab; Wang, Zhijie; Qu, Fengli; Urbanova, Veronika; Etienne, Mathieu; Göllü, Mehmet; Demir, Ayhan S; Gajdzik, Janine; Hempelmann, Rolf

    2011-08-01

    Complexes of the (2,2'-bipyridyl) (pentamethylcyclopentadienyl)-rhodium family ([Cp*Rh(bpy)Cl](+), which is actually hydrolyzed in the form of [Cp*Rh(bpy)H(2)O](2+) in aqueous medium) are suitable solution-phase mediators likely to regenerate nicotinamide cofactors associated to dehydrogenases involved in many biocatalytic applications. Their practical application as bioelectrocatalysts, e.g., in fine chemicals synthesis or biosensors, remains however restricted to their durable immobilization in an active form onto solid electrode surfaces. This paper reports some new observations on the electrocatalytic properties of this mediator towards NAD(+) reduction, notably the critical effect of pH and cofactor-to-mediator concentration ratio, and investigates the behavior of a series of ([Cp*Rh(bpy)Cl](+)) derivatives bearing various substituents on the bipyridine ligand in view of their subsequent integration in electrochemical bioreactors. It will be shown that such compounds containing S- or N- moieties (i.e., often used as precursors to functionalize electrode surfaces) lead to inactivation of the electrocatalyst because their interaction with the Rh center prevents the formation of the active rhodium hydride complex. It was thus necessary to find another strategy of immobilization, and we found that adsorption of [Cp*Rh(bpy)Cl](+) by π-stacking on single-walled carbon nanotubes is an effective mean to reach this goal, leading to efficient and stable catalytic responses for NAD(+) reduction. Preliminary electroenzymatic experiments in the presence of d-sorbitol dehydrogenase further point out the interest of this approach for bioelectrocatalysis purposes and provide the proof-of-concept for this immobilization strategy.

  16. A charge-transfer surface enhanced Raman scattering model from time-dependent density functional theory calculations on a Ag10-pyridine complex.

    Science.gov (United States)

    Birke, Ronald L; Znamenskiy, Vasiliy; Lombardi, John R

    2010-06-07

    Vibrational frequency calculations were made for a Ag(10)-pyridine vertex complex with density functional theory (DFT) for static simulated spectra and with time-dependent DFT (TD-DFT) for preresonance and resonance simulated spectra using both B3LYP/LANL2DZ and BP86/TZP methodologies. In addition, 40 excited states of the complex were calculated and assigned symmetry based on a C(2v) symmetry of the optimized complex found with B3LYP/LANL2DZ. Molecular orbital isosurfaces show that the excited states involve both Ag(10) intercluster excitations and charge-transfer (CT) excitations between the Ag nanocluster and the pyridine molecule. An excitation around 500 nm involving CT from the Ag cluster to pyridine was found in both calculations. For free pyridine, the relative average deviations between unscaled calculated and experimental results were 1.5 cm(-1) for BP86 and 3.1 cm(-1) for the B3LYP calculations. For the complex, simulated spectra at a variety of excitation wavelengths were calculated. In the case of 514 nm excitation, the simulated Raman cross section from the TD-DFT calculations (near the CT resonance) was plotted versus Raman shift frequency and compared with an experimental surface enhanced Raman scattering (SERS) spectrum obtained on an oxidation-reduction cycle, ORC roughened Ag electrode. The BP86 TD-DFT calculation with finite damping term showed a better fit to experimental spectrum with respect to both relative intensities and frequencies. The average deviation of the unscaled BP86 calculations for 16 bands in the experimental spectrum was 13.0 cm(-1). The calculated spectrum in both cases shows many contributions from nontotally symmetric as well as totally symmetric modes, indicating the contribution of Herzberg-Teller (HT) scattering. The simulated intensities of the Raman modes of different symmetry from Ag(10)-pyridine can be correlated with HT intensity borrowing from excited states of given symmetry and decent oscillator strength. These

  17. A Hirshfeld surface analysis, supramolecular structure and magnetic properties of a new Cu(II) complex with the 4-amino-6-methoxypyrimidine ligand

    Science.gov (United States)

    Nbili, W.; Kaabi, K.; Ferenc, W.; Cristovão, B.; Lefebvre, F.; Jelsch, Christian; Ben Nasr, Cherif

    2017-02-01

    A new Cu(II) complex with the bridge bidentate ligand 4-amino-6-methoxypyrimidine, [Cu(C5H7N3O)(H2O)(NO3)2], has been prepared at room temperature and characterized by single crystal X-ray diffraction and IR spectroscopy. The compound crystallizes in the monoclinic space group C2/c with lattice parameters a = 17.783 (4), b = 11.131 (3), c = 12.594 (3) Å, β = 117.616 (3)°, V = 2209.0 (9) Å3 and Z = 8. The Cu(II) cation is hexa-coordinated, in distorted octahedral fashion, by two nitrogen atoms of two 4-amino-6-methoxypyrimidine ligands, one water oxygen atom and three oxygen atoms of two nitrate anions. In the atomic arrangement, the organic ligands and the 6-connected Cu centers are linked with each other to give a 1-D corrugated chain running along the b-axis direction. The chains are interconnected via Osbnd H⋯O, Csbnd H⋯O, Nsbnd H⋯O hydrogen bonds to form a three dimensional network. The analysis of contacts on the Hirshfeld surface shows that the crystal packing is driven mainly by the electrostatic interactions: the coordination of Cu(II) by O and N as well as strong hydrogen bonds. The vibrational absorption bands were identified by infrared spectroscopy. Magnetic properties were also studied to characterize the complex.

  18. Comparison of distribution coefficients (K{sub d} values), sorption isotherms and surface complexation models for evaluating radionuclide sorption in geological media

    Energy Technology Data Exchange (ETDEWEB)

    Payne, Timothy E. [Australian Nuclear Science and Technology Organisation (ANSTO), Menai (Australia); Waite, T. David [School of Civil and Environmental Engineering, University of New South Wales, Sydney (Australia)

    1999-07-01

    The safety assessment of repositories requires models of sorption to be included in the computer codes used for predicting radionuclide migration. Typically, these codes rely on the distribution coefficient (K{sub d} value) to describe sorption. In this paper, the sorption behaviour of U is used as a case study for the development of different types of sorption models. Adsorption isotherms relate the amount of absorbed radionuclide to its dissolved concentration, but usually can not account for the effects of variables such as the pH, ionic strength or the presence of complexing ligands without adjustment of parameter values. The surface complexation model (SCM) offers a more fundamental description of sorption, but requires a large experimental data base, with systematic variation of parameters such as pH and radionuclide concentration. Model uncertainties that derive from the experimental data must be taken into account. The SCM can be used to constrain the range of radionuclide K{sub d} values that may occur in a given environment. (author)

  19. Immobilized molybdenum–thiosemicarbazide Schiff base complex on the surface of magnetite nanoparticles as a new nanocatalyst for the epoxidation of olefins

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadikish, M., E-mail: mohammadikish@yahoo.com [Department of Chemistry, Faculty of Sciences, Kermanshah Branch, Islamic Azad University, Kermanshah (Iran, Islamic Republic of); Masteri-Farahani, M.; Mahdavi, S. [Faculty of Chemistry, Kharazmi University, Tehran (Iran, Islamic Republic of)

    2014-03-15

    In this work, a new magnetically recoverable nanocatalyst was developed by immobilization of thiosemicarbazide ligand on the surface of silica coated magnetite nanoparticles (SCMNPs) through Schiff base condensation and followed complexation with MoO{sub 2}(acac){sub 2}. Characterization of the prepared nanocatalyst was performed with different physicochemical methods such as Fourier transform infrared (FT-IR) and atomic absorption spectroscopies, X-ray diffraction (XRD), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), field-emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The prepared catalyst catalyzed the epoxidation of olefins and allyl alcohols with tert-butyl hydroperoxide (TBHP) and cumene hydroperoxide (CHP) quantitatively with excellent selectivity toward the corresponding epoxides under mild reaction conditions. - Highlights: • Silica coated magnetite nanoparticles were modified with a thiosemicarbazide-Schiff base ligand. • Complexation of the supported ligand with molybdenum resulted in preparation of a new hybrid nanomaterial. • The prepared hybrid nanomaterial acted as an efficient and reusable catalyst in the epoxidation of olefins.

  20. Mixed Self-Assembly of Polyethylene Glycol and Aptamer on Polydopamine Surface for Highly Sensitive and Low-Fouling Detection of Adenosine Triphosphate in Complex Media.

    Science.gov (United States)

    Wang, Guixiang; Xu, Qingjun; Liu, Lei; Su, Xiaoli; Lin, Jiehua; Xu, Guiyun; Luo, Xiliang

    2017-09-13

    Detection of disease biomarkers within complex biological media is a substantial outstanding challenge because of severe biofouling and nonspecific adsorptions. Herein, a reliable strategy for sensitive and low-fouling detection of a biomarker, adenosine triphosphate (ATP) in biological samples was developed through the formation of a mixed self-assembled sensing interface, which was constructed by simultaneously self-assembling polyethylene glycol (PEG) and ATP aptamer onto the self-polymerized polydopamine-modified electrode surface. The developed aptasensor exhibited high selectivity and sensitivity toward the detection of ATP, and the linear range was 0.1-1000 pM, with a detection limit down to 0.1 pM. Moreover, owing to the presence of PEG within the sensing interface, the aptasensor was capable of sensing ATP in complex biological media such as human plasma with significantly reduced nonspecific adsorption effect. Assaying ATP in real biological samples including breast cancer cell lysates further proved the feasibility of this biosensor for practical application.

  1. Research on the Influence of Cutting Rates on Macrogeometry Deflections of Surfaces under Processing Complex form Products Made of Aluminium Aloys

    Directory of Open Access Journals (Sweden)

    Ieva Švagždytė

    2015-03-01

    Full Text Available The article reviews the influence of cutting rates on macrogeometry deflection of milling complex form products and turning an outside surface. For that purpose, one of the most popular aluminium alloys 6082 has been chosen. A ball nose mill of 8 mm in diameter has been milled employing CNC vertical centre HAAS MINI MILL and applying CNC lathe HAAS ST 20 for turning. Measurements have been carried out using coordinate measuring machine DEA micro-hite DCC, applying the probe sphere of 3mm in diameter and the probe equipped with a needle. A deviation of the surface profile from tangent to therophore parabola has been investigated. The determinants R2 of the obtained regressive equation have disclosed that the depth of the cut has the biggest influence on macrogeometry deflections, whereas feed rate has a slighter influence and cutting speed has no radical influence. For the turning process, the depth of the cut has the strongest influence on circularity while cilindrisity has been mainly affected by cutting speed.

  2. Theoretical studies for the N{sub 2}–N{sub 2}O van der Waals complex: The potential energy surface, intermolecular vibrations, and rotational transition frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Rui [Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); School of Mathematics and Information Science, North China University of Water Resources and Electric Power, Zhengzhou 450011 (China); Zheng, Limin; Yang, Minghui, E-mail: yplu@ntu.edu.sg, E-mail: yangmh@wipm.ac.cn [Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); Lu, Yunpeng, E-mail: yplu@ntu.edu.sg, E-mail: yangmh@wipm.ac.cn [Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 (Singapore)

    2015-10-21

    Theoretical studies of the potential energy surface (PES) and bound states are performed for the N{sub 2}–N{sub 2}O van der Waals (vdW) complex. A four-dimensional intermolecular PES is constructed at the level of single and double excitation coupled-cluster method with a non-iterative perturbation treatment of triple excitations [CCSD(T)] with aug-cc-pVTZ basis set supplemented with bond functions. Two equivalent T-shaped global minima are located, in which the O atom of N{sub 2}O monomer is near the N{sub 2} monomer. The intermolecular fundamental vibrational states are assigned by inspecting the orientation of the nodal surface of the wavefunctions. The calculated frequency for intermolecular disrotation mode is 23.086 cm{sup −1}, which is in good agreement with the available experimental data of 22.334 cm{sup −1}. A negligible tunneling splitting with the value of 4.2 MHz is determined for the ground vibrational state and the tunneling splitting increases as the increment of the vibrational frequencies. Rotational levels and transition frequencies are calculated for both isotopomers {sup 14}N{sub 2}–N{sub 2}O and {sup 15}N{sub 2}–N{sub 2}O. The accuracy of the PES is validated by the good agreement between theoretical and experimental results for the transition frequencies and spectroscopic parameters.

  3. 复杂曲面点云非均匀简化技术研究%Research on Nonuniform Reduction of Point Clouds of Complex Surfaces

    Institute of Scientific and Technical Information of China (English)

    高红卫; 刘庆刚

    2014-01-01

    In point clouds reduction of complex surfaces,there exists the problem of feature points losing.The method of automatic division of feature region according to point clouds curvature to real-ize nonuniform reduction is proposed in the paper. First topology relationship of scattered point clouds is set up,and the curvature is calculated out,thus colored curvature diagram is obtained. Then the border of feature region is divided.The reduction efficiency increases with the decrease of the curvature.The point clouds density is high in region with complex detailed feature points.The points are greatly reduced in simple flat region, and the point clouds density is low.The experi-ments show that the value of point clouds reduc-tion ratio is up to 76%.Under the condition of same reduction ratio,the losing of local detained feature can be effectively avoided,and the method has good effect on point clouds reduction of com-plex surfaces.%复杂曲面点云简化时,通常存在特征点丢失问题;提出按照点云曲率云图自动划分特征区域实现非均匀简化。首先建立散乱点云拓扑关系,计算点云曲率,生成彩色曲率云图,之后划分特征区域边界。精简率随着曲率的减小而增大,在复杂细节特征点区域,点云密度大;在简单平坦区域,点云被大量简化,点云密度小。实验表明,精简率达76%,在精简率相同的情况下,该方法能有效避免局部细节特征丢失,对于复杂曲面点云简化有较好的效果。

  4. Metal nanostructures with complex surface morphology: The case of supported lumpy Pd and Pt nanoparticles produced by laser processing of metal films

    Science.gov (United States)

    Ruffino, F.; Maugeri, P.; Cacciato, G.; Zimbone, M.; Grimaldi, M. G.

    2016-09-01

    In this work we report on the formation of lumpy Pd and Pt nanoparticles on fluorine-doped tin oxide/glass (FTO/glass) substrate by a laser-based approach. In general, complex-surface morphology metal nanoparticles can be used in several technological applications exploiting the peculiarities of their physical properties as modulated by nanoscale morphology. For example plasmonic metal nanoparticles presenting a lumpy morphology (i.e. larger particles coated on the surface by smaller particles) can be used in plasmonic solar cell devices providing broadband scattering enhancement over the smooth nanoparticles leading, so, to the increase of the device efficiency. However, the use of plasmonic lumpy nanoparticles remains largely unexplored due to the lack of simply, versatile, low-cost and high-throughput methods for the controllable production of such nanostructures. Starting from these considerations, we report on the observation that nanoscale-thick Pd and Pt films (17.6 and 27.9 nm, 12.1 and 19.5 nm, respectively) deposited on FTO/glass surface irradiated by nanosecond pulsed laser at fluences E in the 0.5-1.5 J/cm2 range, produce Pd and Pt lumpy nanoparticles on the FTO surface. In addition, using scanning electron microscopy analyses, we report on the observation that starting from each metal film of fixed thickness h, the fraction F of lumpy nanoparticles increases with the laser fluence E and saturates at the higher fluences. For each fixed fluence, F was found higher starting from the Pt films (at each starting film thickness h) with respect to the Pd films. For each fixed metal and fluence, F was found to be higher decreasing the starting thickness of the deposited film. To explain the formation of the lumpy Pd and Pt nanoparticles and the behavior of F as a function of E and h both for Pd and Pt, the thermodynamic behavior of the Pd and Pt films and nanoparticles due to the interaction with the nanosecond laser is discussed. In particular, the

  5. Evaluating the suitability of the SWAN/COSMO-2 model system to simulate short-crested surface waves for a narrow lake with complex bathymetry

    Directory of Open Access Journals (Sweden)

    Michael Graf

    2013-07-01

    Full Text Available The spectral wave model SWAN (Simulating Waves Nearshore was applied to Lake Zurich, a narrow pre-Alpine lake in Switzerland. The aim of the study is to investigate whether the model system consisting of SWAN and the numerical weather prediction model COSMO-2 is a suitable tool for wave forecasts for the pre-Alpine Lake Zurich. SWAN is able to simulate short-crested wind-generated surface waves. The model was forced with a time varying wind field taken from COSMO-2 with hourly outputs. Model simulations were compared with measured wave data at one near-shore site during a frontal passage associated with strong on-shore winds. The overall course of the measured wave height is well captured in the SWAN simulation: the wave amplitude significantly increases during the frontal passage followed by a transient drop in amplitude. The wave pattern on Lake Zurich is quite complex. It strongly depends on the inherent variability of the wind field and on the external forcing due to the surrounding complex topography. The influence of the temporal wind resolution is further studied with two sensitivity experiments. The first one considers a low-pass filtered wind field, based on a 2-h running mean of COSMO-2 output, and the second experiment uses simple synthetic gusts, which are implemented into the SWAN model and take into account short-term fluctuations of wind speed at 1-sec resolution. The wave field significantly differs for the 1-h and 2-h simulations, but is only negligibly affected by the gusts.

  6. 复杂型面洁具机器人磨削抛光系统%Robotic grinding and polishing system for complex surface workpiece

    Institute of Scientific and Technical Information of China (English)

    齐立哲; 甘中学; 孙云权; 汤青; 贠超; 吴水华

    2011-01-01

    In order to allow the flexible machining of the complex surface workpieces, a set of robot flexible manufacturing system was developed to achieve the automatic grinding and polishing procoss of the faucet with complex surface. A grinding unit with force cantrol function and conlact wheel online error real time adjustment was designed, allowing online error real time compensation and automatic exchange robot TCP( Tool Center Point); a polishing unit with force control function and wheel radius online detection and compensation function was desigued, it can not only comopensale various kinds of errors of the robot system, but also keep the contact between contact workpiece and polishing wheel even when the polishing wheel radius changes a lot; by applying the robot offline. programming technology, the off-line programming package was developed, improving the programming efficiency and accuracy of the robot; the 3D laser scanming technology was introduced, causing it possible to automatically realize workpice alignment ,online clamping error detection and compensation and assuring the conformity in product manufacturing. This system technology is adyanced and simple to use, and meets the production requirement of the products.%为了实现复杂型面工件的柔性加工,研制了一套机器人柔性加工系统,完成了具有复杂型面水龙头的自动化磨削抛光过程.设计了具有力控制功能及接触轮在线调整功能的磨削单元,可以实现在线误差实时补偿及自动更换机器人TCP(Tool Center Point);设计了具有力控制功能及轮径在线检测与补偿功能的抛光单元,不仅能够实时补偿机器人系统各种误差,而且当抛光轮半径变化很大时,仍能够保证工件与抛光轮接触;采用机器人离线编程技术,设计了离线编程软件,提高了机器人编程效率及精度;采用三维激光扫描技术,能够自动实现工件校准及在线装卡误差检测与补偿,保证产品加工一致

  7. Characteristics of capacitance-micro-displacement for model of complex interior surface of the 3D Taiji ball and its applications

    Science.gov (United States)

    Zhu, Ruo-Gu; Jiang, Kun; Qing, Zhao-Bo; Liu, Yue-Hui; Yan, Jun

    2006-11-01

    Taiji image originated from ancient China. It is not only the Taoism emblem but also the ancient graphic presentation sign to everything origin. It either has a too far-reaching impact on traditional culture of China, or is influencing the development of current natural science. On the basis of analyzing the classical philosophic theory of two-dimensional (2-D) Taiji image, we developed it into the model of complex interior surface-three-dimensional (3-D) Taiji ball, and explored its possible applications. Combining modern mathematics and physics knowledge, we have studied on the physical meaning of 3-D Taiji ball, thus the plane change of original Taiji image is developed into space change which is more close to the real world. The change layers are obvious increased notably, and the amount of information included in this model increases correspondingly. We also realized a special paper 3-D Taiji ball whose surface is coved with metal foil by means of laser manufacture. A new experiment set-up for measuring micro displace has been designed and constituted thus the relation between capacitance and micro displacement for the 3-D Taiji ball has performed. Experimental and theoretical analyses are also finished. This models of 3-D Taiji ball for physical characteristics are the first time set up. Experimental data and fitting curves between capacitance and micro displacement for the special paper Taiji ball coved with metal foil are suggested. It is shown that the special Taiji ball has less leakage capacitance or more strengthen electric field than an ordinary half ball capacitance. Finally their potential applied values are explored.

  8. Development of the "Three-step MACS": a novel strategy for isolating rare cell populations in the absence of known cell surface markers from complex animal tissue.

    Science.gov (United States)

    Lee, Mathia Y; Lufkin, Thomas

    2012-07-01

    To circumvent the difficulty of isolating specific cell populations by MACS from dissociated complex animal tissue, when their proportions reached levels similar to that of the background, we developed the "Three-step MACS" strategy. Cells of interest are defined by their expression of a particular gene(s) of interest rather by than their natural cell surface markers or size. A two-component transgenic cell surface protein, for two sequential rounds of MACS, is expressed under the promoter control of the endogenous gene of interest by means of gene targeting and the generation of transgenic tissue. An initial step to remove dead cells is also used. Here, we describe proof-of-concept experiments, using the biotin acceptor peptide (BAP)-low-affinity nerve growth factor receptor as the two-component protein. The first component, the BAP, can be biotinylated in specific subsets of cells expressing a particular gene by expressing the biotinylating enzyme, hBirA = humanized BirA (hBirA), under the promoter control of another gene defining the specific subpopulation. We showed that a rare population of cells (1.1% of the 13.5 days postcoital mouse embryo) could be enriched to a sufficiently high purity (84.4%). From another sample with 0.1% of our cells of interest, we achieved a 40.3% pure sample. The low cost, speed, and technical ease of the Three-step MACS also make it scalable and hence, an ideal method for preparing sufficient quantities of biological samples for sensitive, high-throughput assays.

  9. Strip Steel Surface Defect Recognition Based on Complex Network Characteristics%基于复杂网络特性的带钢表面缺陷识别

    Institute of Scientific and Technical Information of China (English)

    任海鹏; 马展峰

    2011-01-01

    针对带钢表面缺陷识别问题,提出一种基于动态演化复杂网络特性的特征描述方法,这些特征同时具有位移、旋转不变性、大小不变性、较强的抗干扰能力和鲁棒性,为缺陷识别提供良好的分类特征;为了提高分类器的效率,应用主成分分析法(Principal component analysis,PCA)对复杂网络特征向量进行特征降维处理;采用最优有向无环图支持向量机(Directed acyclic graph support vector machine,DAGSVM)算法进行缺陷分类.结果表明该方法识别率高而且识别速度快.%A feature extraction method based on the characteristics of dynamic evolution complex networks is proposed for the strip steel surface defect recognition. The extracted features possess displacement, rotation and size invariability, strong anti-interference ability and robustness, therefore they are good classification features for steel surface defect recognition. In order to improve the efficiency of classification, the principal component analysis (PCA) is adopted to reduce the dimension of the feature vector. The directed acyclic graph support vector machine (DAG-SVM) algorithm is used for the defect classification. The experimental results show that this method is of high recognition rate and fast recognition speed.

  10. Improving the WRF model's (version 3.6.1) simulation over sea ice surface through coupling with a complex thermodynamic sea ice model (HIGHTSI)

    Science.gov (United States)

    Yao, Yao; Huang, Jianbin; Luo, Yong; Zhao, Zongci

    2016-06-01

    Sea ice plays an important role in the air-ice-ocean interaction, but it is often represented simply in many regional atmospheric models. The Noah sea ice scheme, which is the only option in the current Weather Research and Forecasting (WRF) model (version 3.6.1), has a problem of energy imbalance due to its simplification in snow processes and lack of ablation and accretion processes in ice. Validated against the Surface Heat Budget of the Arctic Ocean (SHEBA) in situ observations, Noah underestimates the sea ice temperature which can reach -10 °C in winter. Sensitivity tests show that this bias is mainly attributed to the simulation within the ice when a time-dependent ice thickness is specified. Compared with the Noah sea ice model, the high-resolution thermodynamic snow and ice model (HIGHTSI) uses more realistic thermodynamics for snow and ice. Most importantly, HIGHTSI includes the ablation and accretion processes of sea ice and uses an interpolation method which can ensure the heat conservation during its integration. These allow the HIGHTSI to better resolve the energy balance in the sea ice, and the bias in sea ice temperature is reduced considerably. When HIGHTSI is coupled with the WRF model, the simulation of sea ice temperature by the original Polar WRF is greatly improved. Considering the bias with reference to SHEBA observations, WRF-HIGHTSI improves the simulation of surface temperature, 2 m air temperature and surface upward long-wave radiation flux in winter by 6, 5 °C and 20 W m-2, respectively. A discussion on the impact of specifying sea ice thickness in the WRF model is presented. Consistent with previous research, prescribing the sea ice thickness with observational information results in the best simulation among the available methods. If no observational information is available, we present a new method in which the sea ice thickness is initialized from empirical estimation and its further change is predicted by a complex thermodynamic

  11. Surface complexation modeling of groundwater arsenic mobility: Results of a forced gradient experiment in a Red River flood plain aquifer, Vietnam

    Science.gov (United States)

    Jessen, Søren; Postma, Dieke; Larsen, Flemming; Nhan, Pham Quy; Hoa, Le Quynh; Trang, Pham Thi Kim; Long, Tran Vu; Viet, Pham Hung; Jakobsen, Rasmus

    2012-12-01

    Three surface complexation models (SCMs) developed for, respectively, ferrihydrite, goethite and sorption data for a Pleistocene oxidized aquifer sediment from Bangladesh were used to explore the effect of multicomponent adsorption processes on As mobility in a reduced Holocene floodplain aquifer along the Red River, Vietnam. The SCMs for ferrihydrite and goethite yielded very different results. The ferrihydrite SCM favors As(III) over As(V) and has carbonate and silica species as the main competitors for surface sites. In contrast, the goethite SCM has a greater affinity for As(V) over As(III) while PO43- and Fe(II) form the predominant surface species. The SCM for Pleistocene aquifer sediment resembles most the goethite SCM but shows more Si sorption. Compiled As(III) adsorption data for Holocene sediment was also well described by the SCM determined for Pleistocene aquifer sediment, suggesting a comparable As(III) affinity of Holocene and Pleistocene aquifer sediments. A forced gradient field experiment was conducted in a bank aquifer adjacent to a tributary channel to the Red River, and the passage in the aquifer of mixed groundwater containing up to 74% channel water was observed. The concentrations of As (SCM correctly predicts desorption for As(III) but for Si and PO43- it predicts an increased adsorption instead of desorption. The goethite SCM correctly predicts desorption of both As(III) and PO43- but failed in the prediction of Si desorption. These results indicate that the prediction of As mobility, by using SCMs for synthetic Fe-oxides, will be strongly dependent on the model chosen. The SCM based on the Pleistocene aquifer sediment predicts the desorption of As(III), PO43- and Si quite superiorly, as compared to the SCMs for ferrihydrite and goethite, even though Si desorption is still somewhat under-predicted. The observation that a SCM calibrated on a different sediment can predict our field results so well suggests that sediment based SCMs may be a

  12. Complex chemical composition of colored surface films formed from reactions of propanal in sulfuric acid at upper troposphere/lower stratosphere aerosol acidities.

    Science.gov (United States)

    Van Wyngarden, A L; Pérez-Montaño, S; Bui, J V H; Li, E S W; Nelson, T E; Ha, K T; Leong, L; Iraci, L T

    Particles in the upper troposphere and lower stratosphere (UT/LS) consist mostly of concentrated sulfuric acid (40-80 wt %) in water. However, airborne measurements have shown that these particles also contain a significant fraction of organic compounds of unknown chemical composition. Acid-catalyzed reactions of carbonyl species are believed to be responsible for significant transfer of gas phase organic species into tropospheric aerosols and are potentially more important at the high acidities characteristic of UT/LS particles. In this study, experiments combining sulfuric acid (H2SO4) with propanal and with mixtures of propanal with glyoxal and/or methylglyoxal at acidities typical of UT/LS aerosols produced highly colored surface films (and solutions) that may have implications for aerosol properties. In order to identify the chemical processes responsible for the formation of the surface films, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and (1)H nuclear magnetic resonance (NMR) spectroscopies were used to analyze the chemical composition of the films. Films formed from propanal were a complex mixture of aldol condensation products, acetals and propanal itself. The major aldol condensation products were the dimer (2-methyl-2-pentenal) and 1,3,5-trimethylbenzene that was formed by cyclization of the linear aldol condensation trimer. Additionally, the strong visible absorption of the films indicates that higher-order aldol condensation products must also be present as minor species. The major acetal species were 2,4,6-triethyl-1,3,5-trioxane and longer-chain linear polyacetals which are likely to separate from the aqueous phase. Films formed on mixtures of propanal with glyoxal and/or methylglyoxal also showed evidence of products of cross-reactions. Since cross-reactions would be more likely than self-reactions under atmospheric conditions, similar reactions of aldehydes like propanal with common aerosol organic species like glyoxal and

  13. Hume-Rothery stabilisation mechanism and d-states-mediated Fermi surface-Brillouin zone interactions in structurally complex metallic alloys

    Science.gov (United States)

    Mizutani, U.; Inukai, M.; Sato, H.

    2011-07-01

    The stability of Co2Zn11 and Al8V5 gamma-brasses, both of which are composed of a transition metal element and polyvalent elements Zn or Al, can be discussed in terms of d-states-mediated Fermi surface-Brillouin zone (FsBz) interactions in the context of first-principles full-potential linearised augmented plane wave (FLAPW) band calculations. A FsBz-induced pseudogap is revealed in the FLAPW-Fourier spectrum, though it is hidden behind a much larger d-band in the total density of states. The stability range of three families of complex metallic alloys (CMAs) that include gamma-brasses, RT-, MI- and Tsai-type 1/1-1/1-1/1 approximants and 2/1-2/1-2/1 approximant, each of which is characterised by ? = 18, 50 and 125, respectively, can be well scaled in terms of the number of electrons per unit cell (e/uc) given by the product of the number of atoms per unit cell and the e/a value determined by the Hume-Rothery plot on the basis of the FLAPW-Fourier method. This is taken as the evidence for the justification of the Hume-Rothery stabilisation mechanism for all these CMAs having a pseudogap at the Fermi level.

  14. Modeling Np and Pu transport with a surface complexation model and spatially variant sorption capacities: Implications for reactive transport modeling and performance assessments of nuclear waste disposal sites

    Science.gov (United States)

    Glynn, P.D.

    2003-01-01

    One-dimensional (1D) geochemical transport modeling is used to demonstrate the effects of speciation and sorption reactions on the ground-water transport of Np and Pu, two redox-sensitive elements. Earlier 1D simulations (Reardon, 1981) considered the kinetically limited dissolution of calcite and its effect on ion-exchange reactions (involving 90Sr, Ca, Na, Mg and K), and documented the spatial variation of a 90Sr partition coefficient under both transient and steady-state chemical conditions. In contrast, the simulations presented here assume local equilibrium for all reactions, and consider sorption on constant potential, rather than constant charge, surfaces. Reardon's (1981) seminal findings on the spatial and temporal variability of partitioning (of 90Sr) are reexamined and found partially caused by his assumption of a kinetically limited reaction. In the present work, sorption is assumed the predominant retardation process controlling Pu and Np transport, and is simulated using a diffuse-double-layer-surface-complexation (DDLSC) model. Transport simulations consider the infiltration of Np- and Pu-contaminated waters into an initially uncontaminated environment, followed by the cleanup of the resultant contamination with uncontaminated water. Simulations are conducted using different spatial distributions of sorption capacities (with the same total potential sorption capacity, but with different variances and spatial correlation structures). Results obtained differ markedly from those that would be obtained in transport simulations using constant Kd, Langmuir or Freundlich sorption models. When possible, simulation results (breakthrough curves) are fitted to a constant K d advection-dispersion transport model and compared. Functional differences often are great enough that they prevent a meaningful fit of the simulation results with a constant K d (or even a Langmuir or Freundlich) model, even in the case of Np, a weakly sorbed radionuclide under the

  15. Modeling and optimization of photo-Fenton degradation of 2,4-D using ferrioxalate complex and response surface methodology (RSM).

    Science.gov (United States)

    Schenone, Agustina V; Conte, Leandro O; Botta, María A; Alfano, Orlando M

    2015-05-15

    This study reports the application of the photo-Fenton process for the degradation of the herbicide 2,4-dichlorophenoxyacetic (2,4-D). The objective of this research was the evaluation of the procedure at natural pH (pH = 5) using the ferrioxalate complex as iron source at two incident irradiation levels. For this purpose, different combinations of attenuation filters from a solar simulator were tested. Since the process depends on several parameters, the influence of the temperature (T) and peroxide to 2,4-D initial concentration ratio (R) were investigated and optimized by the application of a three-level factorial experimental design combined with the Response Surface Methodology (RSM). The significance of models and their coefficients were assessed with the analysis of variance (ANOVA). The found optimal conditions were: T = 50 °C and R = 46.3 and T = 41.53 °C and R = 41.46, achieving experimental conversions of 91.4 and 95.9% for the low and high radiation levels, respectively. The obtained results are very close to the values predicted by the quadratic models (93.8 and 100.0%). It was concluded that temperature and hydrogen peroxyde concentration have different influences on the response factor depending on the incident irradiation level. It was demonstrated that RSM is a good tool for studying the effects of different variables and their interactions on 2,4-D conversion percentage in the photo-Fenton process. In addition, solution acute toxicity was also evaluated during the treatments under optimum conditions, since some degradation by-products of 2,4-D can be more toxic than the parent compound. For this purpose, the commonly used Microtox(®) test based on the bacteria Vibrio fischeri was employed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Lessons from the Crystal Structure of the S. aureus Surface Protein Clumping Factor A in Complex With Tefibazumab, an Inhibiting Monoclonal Antibody

    Directory of Open Access Journals (Sweden)

    Vannakambadi K. Ganesh

    2016-11-01

    Full Text Available The Staphylococcus aureus fibrinogen binding MSCRAMM (Microbial Surface Components Recognizing Adhesive Matrix Molecules, ClfA (clumping factor A is an important virulence factor in staphylococcal infections and a component of several vaccines currently under clinical evaluation. The mouse monoclonal antibody aurexis (also called 12-9, and the humanized version tefibazumab are therapeutic monoclonal antibodies targeting ClfA that in combination with conventional antibiotics were effective in animal models but showed less impressive efficacy in a limited Phase II clinical trial. We here report the crystal structure and a biochemical characterization of the ClfA/tefibazumab (Fab complex. The epitope for tefibazumab is located to the “top” of the N3 subdomain of ClfA and partially overlaps with a previously unidentified second binding site for fibrinogen. A high-affinity binding of ClfA to fibrinogen involves both an interaction at the N3 site and the previously identified docking of the C-terminal segment of the fibrinogen γ-chain in the N2N3 trench. Although tefibazumab binds ClfA with high affinity we observe a modest IC50 value for the inhibition of fibrinogen binding to the MSCRAMM. This observation, paired with a common natural occurring variant of ClfA that is not effectively recognized by the mAb, may partly explain the modest effect tefibazumab showed in the initial clinic trail. This information will provide guidance for the design of the next generation of therapeutic anti-staphylococcal mAbs targeting ClfA.

  17. Studies of surface complexation of H{sup +}, NpO{sub 2}{sup +}, Co{sup 2+}, Th{sup 4+} onto TiO{sub 2} and H{sup +}, UO{sub 2}{sup 2+} onto alumina

    Energy Technology Data Exchange (ETDEWEB)

    Jakobsson, Anna-Maria; Albinsson, Yngve [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Nuclear Chemistry; Rundberg, R.S. [Los Alamos National Lab., NM (United States)

    1998-11-01

    This report describes the determination of surface complexation reactions of some radionuclides on mineral oxides from sorption experiments and potentiometric titrations. The surface acidity constants of the mineral oxide have been determined using potentiometric titrations. A description and discussion of the extrapolation method used is included as well as the calibration method which is of uttermost importance for calculating the constants. In this report it