WorldWideScience

Sample records for surface charge-charge interactions

  1. Laser-surface interactions

    CERN Document Server

    Ganeev, Rashid A

    2014-01-01

    This book is about the interaction of laser radiation with various surfaces at variable parameters of radiation. As a basic principle of classification we chose the energetic or intensity level of interaction of laser radiation with the surfaces. These two characteristics of laser radiation are the most important parameters defining entire spectrum of the processes occurring on the surfaces during interaction with electromagnetic waves. This is a first book containing a whole spectrum of the laser-surface interactions distinguished by the ranges of used laser intensity. It combines the surface response starting from extremely weak laser intensities (~1 W cm-2) up to the relativistic intensities (~1020 W cm-2 and higher). The book provides the basic information about lasers and acquaints the reader with both common applications of laser-surface interactions (laser-related printers, scanners, barcode readers, discs, material processing, military, holography, medicine, etc) and unusual uses of the processes on t...

  2. Tritium-surface interactions

    International Nuclear Information System (INIS)

    Kirkaldy, J.S.

    1983-06-01

    The report deals broadly with tritium-surface interactions as they relate to a fusion power reactor enterprise, viz., the vacuum chamber, first wall, peripherals, pumping, fuel recycling, isotope separation, repair and maintenance, decontamination and safety. The main emphasis is on plasma-surface interactions and the selection of materials for fusion chamber duty. A comprehensive review of the international (particularly U.S.) research and development is presented based upon a literature review (about 1 000 reports and papers) and upon visits to key laboratories, Sandia, Albuquerque, Sandia, Livermore and EGβG Idaho. An inventory of Canadian expertise and facilities for RβD on tritium-surface interactions is also presented. A number of proposals are made for the direction of an optimal Canadian RβD program, emphasizing the importance of building on strength in both the technological and fundamental areas. A compendium of specific projects and project areas is presented dealing primarily with plasma-wall interactions and permeation, anti-permeation materials and surfaces and health, safety and environmental considerations. Potential areas of industrial spinoff are identified

  3. Plasma-surface interactions

    International Nuclear Information System (INIS)

    Goeckner, M J; Nelson, C T; Sant, S P; Jindal, A K; Joseph, E A; Zhou, B S; Padron-Wells, G; Jarvis, B; Pierce, R; Overzet, L J

    2008-01-01

    Materials processing is at a crossroads. Currently a large fraction of industrially viable materials processing is via plasmas. Until recently it has been economical to just examine the influence the plasma properties on the desired surface processes and through this ultimately optimize manufacturing. For example, it is well known that the surface processes (etch or deposition), occur in the top few mono-layers of the surface. Thus, in film growth one requires that molecules from the gas-phase land and bond on the surface. However as processing has reached the nano-scale, development of viable processes has become more and more difficult. In part, this is because of all of the free parameters that exist in plasmas. To overcome this economic issue, tool vendors and semiconductor companies have turned to complex computational models of processing plasmas. For those models to work, one requires a through understanding of all of the gas-phase and surface-phase processes that are exhibited in plasmas. Unfortunately, these processes, particularly those at the surface, are not well understood. In this article we describe a viable model of the surface-phase based on cross sections for processes that occur. While originally developed of fluorocarbon systems, the model also appears to be applicable to hydrocarbon systems.

  4. Nitrogen interactions at metal surfaces

    NARCIS (Netherlands)

    Gleeson, M.A.; Kleijn, A.W.

    2013-01-01

    Molecular beam experiments with specially prepared beams allow the study of the interaction of very reactive species with surfaces. In the present case the interaction of N-atoms with Ag(1 1 1) is studied. The energy of the atoms is around 5 eV, precisely between the classical energy regimes of

  5. Modelling land surface - atmosphere interactions

    DEFF Research Database (Denmark)

    Rasmussen, Søren Højmark

    related to inaccurate land surface modelling, e.g. enhanced warm bias in warm dry summer months. Coupling the regional climate model to a hydrological model shows the potential of improving the surface flux simulations in dry periods and the 2 m air temperature in general. In the dry periods......The study is investigates modelling of land surface – atmosphere interactions in context of fully coupled climatehydrological model. With a special focus of under what condition a fully coupled model system is needed. Regional climate model inter-comparison projects as ENSEMBLES have shown bias...

  6. Collaboration Meets Interactive Surfaces (CMIS)

    DEFF Research Database (Denmark)

    Anslow, Craig; Campos, Pedro; Grisoni, Laurent

    2015-01-01

    This workshop proposes to bring together researchers who are interested in improving collaborative experiences through the combination of multiple interaction surfaces with diverse sizes and formats, ranging from large-scale walls, to tables, mobiles, and wearables. The opportunities for innovati...

  7. Modelling land surface - atmosphere interactions

    DEFF Research Database (Denmark)

    Rasmussen, Søren Højmark

    The study is investigates modelling of land surface – atmosphere interactions in context of fully coupled climatehydrological model. With a special focus of under what condition a fully coupled model system is needed. Regional climate model inter-comparison projects as ENSEMBLES have shown bias...

  8. Charge-charge liquid structure factor and the freezing of alkali halides

    International Nuclear Information System (INIS)

    March, N.H.; Tosi, M.P.

    1980-10-01

    The peak height of the charge-charge liquid structure factor Ssub(QQ) in molten alkali halides is proposed as a criterion for freezing. Available data on molten alkali chlorides, when extrapolated to the freezing point suggests Ssub(QQ)sup(max) approximately 5. (author)

  9. Interactive Design of Developable Surfaces

    KAUST Repository

    Tang, Chengcheng

    2016-01-15

    We present a new approach to geometric modeling with developable surfaces and the design of curved-creased origami. We represent developables as splines and express the nonlinear conditions relating to developability and curved folds as quadratic equations. This allows us to utilize a constraint solver, which may be described as energy-guided projection onto the constraint manifold, and which is fast enough for interactive modeling. Further, a combined primal-dual surface representation enables us to robustly and quickly solve approximation problems.

  10. Cell surface engineering to control cellular interactions

    OpenAIRE

    Custódio, Catarina A.; Mano, João F.

    2016-01-01

    Cell surface composition determines all interactions of the cell with its environment, thus cell functions such as adhesion, migration and cell–cell interactions can potentially be controlled by engineering and manipulating the cell membrane. Cell membranes present a rich repertoire of molecules, therefore a versatile ground for modification. However the complex and dynamic nature of the cell surface is also a major challenge for cell surface engineering that should also involve strategies co...

  11. Surface Water Interactions using Environmental Isotopes

    Indian Academy of Sciences (India)

    40

    lead to the deterioration of water quality of both surface and groundwater. One of the important features of karst terrains is the interaction between surface water and groundwater, which has been the subject of interest for many researchers because of the potential of contamination of the aquifer from surface water recharge.

  12. Interaction between heterogeneously charged surfaces: surface patches and charge modulation.

    Science.gov (United States)

    Ben-Yaakov, Dan; Andelman, David; Diamant, Haim

    2013-02-01

    When solid surfaces are immersed in aqueous solutions, some of their charges can dissociate and leave behind charged patches on the surface. Although the charges are distributed heterogeneously on the surface, most of the theoretical models treat them as homogeneous. For overall non-neutral surfaces, the assumption of surface charge homogeneity is rather reasonable since the leading terms of two such interacting surfaces depend on the nonzero average charge. However, for overall neutral surfaces the nature of the surface charge distribution is crucial in determining the intersurface interaction. In the present work we study the interaction between two charged surfaces across an aqueous solution for several charge distributions. The analysis is preformed within the framework of the linearized Poisson-Boltzmann theory. For periodic charge distributions the interaction is found to be repulsive at small separations, unless the two surface distributions are completely out-of-phase with respect to each other. For quenched random charge distributions we find that due to the presence of the ionic solution in between the surfaces, the intersurface repulsion dominates over the attraction in the linear regime of the Poisson-Boltzmann theory. The effect of quenched charge heterogeneity is found to be particularly substantial in the case of large charged domains.

  13. Knocking on surfaces : interactions of hyperthermal particles with metal surfaces

    NARCIS (Netherlands)

    Ueta, Hirokazu

    2010-01-01

    The study of gas-surface interaction dynamics is important both for the fundamental knowledge it provides and also to aid the development of applications involving processes such as sputtering, plasma etching and heterogeneous catalysis. Elementary steps in the interactions, such as chemical

  14. Organic chemistry on Titan: Surface interactions

    Science.gov (United States)

    Thompson, W. Reid; Sagan, Carl

    1992-01-01

    The interaction of Titan's organic sediments with the surface (solubility in nonpolar fluids) is discussed. How Titan's sediments can be exposed to an aqueous medium for short, but perhaps significant, periods of time is also discussed. Interactions with hydrocarbons and with volcanic magmas are considered. The alteration of Titan's organic sediments over geologic time by the impacts of meteorites and comets is discussed.

  15. Interaction of gases with solid surfaces

    Science.gov (United States)

    Borisov, Sergei F.; Balakhonov, Nikifor F.; Gubanov, Vladimir A.

    Various problems related to the interaction of gases with solid surfaces are examined theoretically and experimentally. In particular, attention is given to the scattering of molecules by surfaces in the nonequilibrium system gas-solid; heat transfer in gas-solid systems over a wide range of Knudsen numbers; adsorption processes at the gas-solid interface; and thermal accommodation of gases on a controlled surface. The discussion also covers kinetic equations for the nonequilibrium heterogeneous system gas-solid; scattering nucleus and accommodation coefficients on solid surfaces; and quantum-chemical calculations of the electron states of a solid surface.

  16. Simulation of Gas-Surface Dynamical Interactions

    Science.gov (United States)

    2007-07-01

    surface. The substrate with lattice constant a is represented in a simple ball and spring picture. on the particular problem. Time-independent...παvwell , (26) Simulation of Gas-Surface Dynamical Interactions 4 - 10 RTO-EN-AVT-142 g E ad v mvc ∆ v’well vc cM Figure 4

  17. Hydrogeological controls of groundwater - land surface interactions

    Science.gov (United States)

    Bresciani, Etienne; Batelaan, Okke; Goderniaux, Pascal

    2017-04-01

    Interaction of groundwater with the land surface impacts a wide range of climatic, hydrologic, ecologic and geomorphologic processes. Many site-specific studies have successfully focused on measuring and modelling groundwater-surface water interaction, but upscaling or estimation at catchment or regional scale appears to be challenging. The factors controlling the interaction at regional scale are still poorly understood. In this contribution, a new 2-D (cross-sectional) analytical groundwater flow solution is used to derive a dimensionless criterion that expresses the conditions under which the groundwater outcrops at the land surface (Bresciani et al., 2016). The criterion gives insights into the functional relationships between geology, topography, climate and the locations of groundwater discharge along river systems. This sheds light on the debate about the topographic control of groundwater flow and groundwater-surface water interaction, as effectively the topography only influences the interaction when the groundwater table reaches the land surface. The criterion provides a practical tool to predict locations of groundwater discharge if a limited number of geomorphological and hydrogeological parameters (recharge, hydraulic conductivity and depth to impervious base) are known, and conversely it can provide regional estimates of the ratio of recharge over hydraulic conductivity if locations of groundwater discharge are known. A case study with known groundwater discharge locations located in South-West Brittany, France shows the feasibility of regional estimates of the ratio of recharge over hydraulic conductivity. Bresciani, E., Goderniaux, P. and Batelaan, O., 2016, Hydrogeological controls of water table-land surface interactions. Geophysical Research Letters 43(18): 9653-9661. http://dx.doi.org/10.1002/2016GL070618

  18. Bonding and interaction of molecules with surfaces

    International Nuclear Information System (INIS)

    Ellis, D.E.

    1988-01-01

    In this lecture it is intended to discuss some general features of bonding and interaction of molecules with surfaces. The geometry of surface complexes is sufficiently difficult and the interaction mechanisms are sufficiently subtle. That all possible theoretical models need to be exploited such as: i) Semiempirical - including Huckel molecular orbital theory; ii)first principles including self-consistent-field Hartree-Fock and Local Density approaches; iii)explicitly correlated, including C.I., Generalized Valence Bond, Coupled Cluster Perturbation Theory and Many Body Perturbation Theory. (A.C.A.S.) [pt

  19. Acetic acid mediated interactions between alumina surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Kimiyasu, E-mail: sato.kimiyasu@aist.go.jp [National Institute of Advanced Industrial Science and Technology (AIST), Anagahora 2266-98, Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan); Y Latin-Small-Letter-Dotless-I lmaz, Hueseyin [National Institute of Advanced Industrial Science and Technology (AIST), Anagahora 2266-98, Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan); Gebze Institute of Technology, Materials Science and Engineering Department, 41400, Gebze-Kocaeli (Turkey); Ijuin, Atsuko; Hotta, Yuji; Watari, Koji [National Institute of Advanced Industrial Science and Technology (AIST), Anagahora 2266-98, Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan)

    2012-02-01

    Low-molecular-weight organic acids have been known to modify colloidal stability of alumina-based suspensions. We investigated interaction forces between alumina surfaces mediated by acetic acid which is one of the simplest organic acids. Forces between alumina surfaces were measured using the colloid-probe method of atomic force microscope (AFM). Repulsive forces attributed to steric repulsion due to adsorbed molecules and electrostatic repulsion dominated the interaction. Results of rheological characterization of the alumina slurry containing acetic acid supported the finding.

  20. Interaction of nitrogen ions with beryllium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Dobes, Katharina [Institute of Applied Physics, TU Wien, Association EURATOM ÖAW, Vienna (Austria); Köppen, Martin [Institute of Energy and Climate Research – Plasma Physics, Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Oberkofler, Martin [Max-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, D-85748 Garching (Germany); Lungu, Cristian P.; Porosnicu, Corneliu [National Institute for Laser, Plasma, and Radiation Physics, Bucharest (Romania); Höschen, Till; Meisl, Gerd [Max-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, D-85748 Garching (Germany); Linsmeier, Christian [Institute of Energy and Climate Research – Plasma Physics, Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Aumayr, Friedrich, E-mail: aumayr@iap.tuwien.ac.at [Institute of Applied Physics, TU Wien, Association EURATOM ÖAW, Vienna (Austria)

    2014-12-01

    The interaction of energetic nitrogen projectiles with a beryllium surface is studied using a highly sensitive quartz crystal microbalance technique. The overall mass change rate of the beryllium sample under N{sub 2}{sup +} ion impact at an ion energy of 5000 eV (i.e. 2500 eV per N) is investigated in situ and in real-time. A strong dependency of the observed mass change rate on the nitrogen fluence (at constant flux) is found and can be attributed to the formation of a nitrogen-containing mixed material layer within the ion penetration depth. The presented data elucidate the dynamics of the interaction process and the surface saturation with increasing nitrogen fluence in a unique way. Basically, distinct interaction regimes can be discriminated, which can be linked to the evolution of the surface composition upon nitrogen impact. Steady state surface conditions are obtained at a total cumulative nitrogen fluence of ∼80 × 10{sup 16} N atoms per cm{sup 2}. In dynamic equilibrium, the interaction is marked by continuous surface erosion. In this case, the observed total sputtering yield becomes independent from the applied nitrogen fluence and is of the order of 0.4 beryllium atoms per impinging nitrogen atom.

  1. Plasma surface interactions in controlled fusion devices

    Energy Technology Data Exchange (ETDEWEB)

    Ghendrih, Ph.; Becoulet, M.; Costanzo, L. [and others

    2000-07-01

    This report brings together all the contributions of EURATOM/CEA association to the 14. international conference on plasma surface interactions in controlled fusion devices. 24 papers are presented and they deal mainly with the ergodic divertor and the first wall of Tore-supra tokamak.

  2. Plasma-Surface Interaction Activities in KSTAR

    NARCIS (Netherlands)

    Hong, S. H.; Yu, Y.; Kim, K. P.; Bak, J. G.; Park, H. J.; Oh, Y. S.; Chung, J.; Nam, Y. U.; Bang, E. N.; Kim, K. R.; Litnovsky, A.; Hellwig, M.; Matveev, D.; Komm, M.; van den Berg, M. A.; Kim, W. C.; Kim, H. K.; Rho, T. H.; Chu, Y.; Oh, Y. K.; Yang, H. L.; Park, K. R.; Chung, K. S.; Kstar Team,

    2013-01-01

    Selected topics of Plasma-Surface Interaction (PSI) activities in KSTAR are briefly introduced. SOL parameter measurements, particle balance and fuel retention, in-vessel dust research, and finally tungsten R & D are discussed. Some quantitative numbers from the initial phase of the operation

  3. Surface Water Interactions using Environmental Isotopes

    Indian Academy of Sciences (India)

    40

    Quantification of Groundwater - Surface Water Interactions using Environmental. Isotopes; A Case Study of Bringi Watershed, Kashmir Himalayas, India. Nadeem A. Bhat* and Gh. Jeelani. Department of Earth Sciences, University of Kashmir, Srinagar, J&K 190 006, India. *Correspondence to: Nadeem A. Bhat. E-mail: ...

  4. Interactions between whey proteins and kaolinite surfaces

    International Nuclear Information System (INIS)

    Barral, S.; Villa-Garcia, M.A.; Rendueles, M.; Diaz, M.

    2008-01-01

    The nature of the interactions between whey proteins and kaolinite surfaces was investigated by adsorption-desorption experiments at room temperature, performed at the isoelectric point (IEP) of the proteins and at pH 7. It was found that kaolinite is a strong adsorbent for proteins, reaching the maximum adsorption capacity at the IEP of each protein. At pH 7.0, the retention capacity decreased considerably. The adsorption isotherms showed typical Langmuir characteristics. X-ray diffraction data for the protein-kaolinite complexes showed that protein molecules were not intercalated in the mineral structure, but immobilized at the external surfaces and the edges of the kaolinite. Fourier transform IR results indicate the absence of hydrogen bonding between kaolinite surfaces and the polypeptide chain. The adsorption patterns appear to be related to electrostatic interactions, although steric effects should be also considered

  5. Synergistic effects in plasma surface interactions

    International Nuclear Information System (INIS)

    Roberto, J.B.; Behrisch, R.

    1984-01-01

    The possible synergistic effects which can contribute to plasma surface interaction phenomena in fusion devices are reviewed. These effects include the influence of reactive ions, surface modification, temperature, radiation damage, and external forces and fields on erosion yields, hydrogen retention and release, and other surface processes. The important synergistic effects are described in terms of surface and edge conditions encountered in present fusion devices and expected in future reactors. Priority data needs include the chemical erosion of graphite at high particle fluxes, melt-layer stability under disruption-induced eddy current forces, the influence of bulk neutron damage on hydrogen retention, and an in-situ evaluation of synergistic effects in operating fusion devices

  6. Interaction of oxygen with zirconia surface

    International Nuclear Information System (INIS)

    Ivankiv, L.I.; Ketsman, I.V.

    1999-01-01

    The influence of surface heat treatment, electron (50-800) eV irradiation and UV (180-300) nM illumination of adsorption system on the state of oxygen adsorbed on zirconia surface have been investigated. On the basis of experimental results obtained by investigation of photon emission accompanying oxygen adsorption (AL) and TPD data existence of adsorption sites on the surface is suggested on which irreversible dissociative adsorption of oxygen occurs. These very sites are associated with emission processes Conclusion is made that the only type of adsorption sites connected with anion vacancy is present on zirconia surface and this is its charge state that determines the state of adsorbed oxygen. One of the important mechanisms by which the electron and UV photon excitation affects the adsorption interaction is the change of the charge state of the adsorption site

  7. Interaction of alcohols with the calcite surface

    DEFF Research Database (Denmark)

    Bovet, Nicolas Emile; Yang, Mingjun; Javadi, Meshkat Sadat

    2015-01-01

    . Controlling their growth requires complex polysaccharides. Polysaccharide activity depends on the functionality of OH groups, so to simplify the system in order to get closer to a molecular level understanding, we investigated the interaction of OH from a suite of alcohols with clean, freshly cleaved calcite...... surfaces. X-ray photoelectron spectroscopy (XPS) provided binding energies and revealed the extent of surface coverage. Molecular dynamics (MD) simulations supplemented with information about molecule ordering, orientation and packing density. The results show that all alcohols studied bond...... with the calcite surface through the OH group, with their carbon chains sticking away in a standing-up orientation. Alcohol molecules are closely packed and form a well-ordered monolayer on the surface....

  8. Modelling of energetic molecule-surface interactions

    International Nuclear Information System (INIS)

    Kerford, M.

    2000-09-01

    This thesis contains the results of molecular dynamics simulations of molecule-surface interactions, looking particularly at fullerene molecules and carbon surfaces. Energetic impacts of fullerene molecules on graphite create defect craters. The relationship between the parameters of the impacting molecule and the parameters of the crater axe examined and found to be a function of the energy and velocity of the impacting molecule. Less energetic fullerene molecules can be scattered from a graphite surface and the partitioning of energy after a scattering event is investigated. It is found that a large fraction of the kinetic energy retained after impact is translational energy, with a small fraction of rotational energy and a number of vibrational modes. At impact energies where the surface is not broken and at normal incidence, surface waves axe seen to occur. These waves axe used to develop a method of desorbing molecules from a graphite surface without damage to either the surface or the molecules being desorbed. A number of fullerene molecules are investigated and ways to increase the desorption yield are examined. It is found that this is a successful technique for desorbing large numbers of intact molecules from graphite. This technique could be used for desorbing intact molecules into a gas phase for mass spectrometric analysis. (author)

  9. Atmosphere-surface interactions over polar oceans and heterogeneous surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Vihma, T.

    1995-12-31

    Processes of interaction between the atmospheric boundary layer and the planetary surface have been studied with special emphasis on polar ocean surfaces: the open ocean, leads, polynyas and sea ice. The local exchange of momentum, heat and moisture has been studied experimentally both in the Weddell Sea and in the Greenland Sea. Exchange processes over heterogeneous surfaces are addressed by modelling studies. Over a homogeneous surface, the local turbulent fluxes can be reasonably well estimated using an iterative flux-profile scheme based on the Monin-Obukhov similarity theory. In the Greenland Sea, the near-surface air temperature and the generally small turbulent fluxes over the open ocean were affected by the sea surface temperature fronts. Over the sea ice cover in the Weddell Sea, the turbulent sensible heat flux was generally downwards, and together with an upward oceanic heat flux through the ice it compensated the heat loss from the surface via long-wave radiation. The wind dominated on time scales of days, while the current became important on longer time scales. The drift dynamics showed apparent spatial differences between the eastern and western regions, as well as between the Antarctic Circumpolar Current and the rest of the Weddell Sea. Inertial motion was present in regions of low ice concentration. The surface heterogeneity, arising e.g. from roughness or temperature distribution, poses a problem for the parameterization of surface exchange processes in large-scale models. In the case of neutral flow over a heterogeneous terrain, an effective roughness length can be used to parameterize the roughness effects

  10. Interaction of alcohols with the calcite surface.

    Science.gov (United States)

    Bovet, N; Yang, M; Javadi, M S; Stipp, S L S

    2015-02-07

    A clearer understanding of calcite interactions with organic molecules would contribute to a range of fields including harnessing the secrets of biomineralisation where organisms produce hard parts, increasing oil production from spent reservoirs, remediating contaminated soils and drinking water aquifers and improving manufacturing methods for industrial products such as pigments, soft abrasives, building materials and optical devices. Biomineralisation by some species of blue green algae produces beautifully elaborate platelets of calcite where the individual crystals are of nanometer scale. Controlling their growth requires complex polysaccharides. Polysaccharide activity depends on the functionality of OH groups, so to simplify the system in order to get closer to a molecular level understanding, we investigated the interaction of OH from a suite of alcohols with clean, freshly cleaved calcite surfaces. X-ray photoelectron spectroscopy (XPS) provided binding energies and revealed the extent of surface coverage. Molecular dynamics (MD) simulations supplemented with information about molecule ordering, orientation and packing density. The results show that all alcohols studied bond with the calcite surface through the OH group, with their carbon chains sticking away in a standing-up orientation. Alcohol molecules are closely packed and form a well-ordered monolayer on the surface.

  11. Plasma diagnostics surface analysis and interactions

    CERN Document Server

    Auciello, Orlando

    2013-01-01

    Plasmas and their interaction with materials have become subjects of major interest because of their importance in modern forefront technologies such as microelectronics, fusion energy, and space. Plasmas are used in microelectronics to process semiconductors (etching of patterns for microcircuits, plasma-induced deposition of thin films, etc.); plasmas produce deleterious erosion effects on surfaces of materials used for fusion devices and spaceships exposed to the low earth environment.Diagnostics of plasmas and materials exposed to them are fundamental to the understanding of the physical a

  12. XIX Conference on Plasma Surface Interactions

    International Nuclear Information System (INIS)

    Kurnaev, V A; Gasparyan, Yu M

    2016-01-01

    The 19 th Conference on Plasma Surface Interactions (PSI-2016) was held at National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) on 28-29 January 2016. This is a traditional annual meeting organized by MEPhI for many years and devoted to the recent achievements of Russian scientists and foreign colleagues in experimental and computer simulations of plasma and its components' interactions with plasma faced materials (PFM) for fusion devices and plasma technologies. The conference agenda covered a broad list of topics including: • plasma induced erosion and modification of materials; • radiation damage in materials; • lithium and liquid metals as PFM; • modeling of plasma surface interaction and processes in SOL of tokamak plasma; • diagnostics of plasma-surface interaction. The aim of the conference was to present and discuss new results in PSI in a wide audience with different areas of expertise. The important feature of the conference is to give PhD and undergraduate students the opportunity for approbation of results of their scientific activity and improve their knowledge in the novel directions of R and D in the field of fusion and plasma technologies. In total, more than 80 experienced and young researchers participated in the conference. These Proceedings contain 21 papers selected for publication, which were reviewed by the invited international team of editors (T. Tanabe, S. Petrovich, Ch. Grisolia, Yu. Martynenko, S. Krasheninnikov, L. Begrambekov, A. Pisarev). The Conference as well as editing of this issue were supported by National Research Nuclear University MEPhI in the framework of the Russian Academic Excellence Project (contract No. 02.a03.21.0005, 27.08.2013). Finally, we would like to thank all of the speakers, participants and organizing committee members for their contribution to the conference. Acknowledgements The organizers of the conference would like to thank for the support from National Research

  13. Plasma-surface interactions under high heat and particle fluxes

    NARCIS (Netherlands)

    De Temmerman, G.; Bystrov, K.; Liu, F.; Liu, W.; Morgan, T.; Tanyeli, I.; van den Berg, M.; Xu, H.; Zielinski, J.

    2013-01-01

    The plasma-surface interactions expected in the divertor of a future fusion reactor are characterized by extreme heat and particle fluxes interacting with the plasma-facing surfaces. Powerful linear plasma generators are used to reproduce the expected plasma conditions and allow plasma-surface

  14. Charge-charge correlations and the detection of weak vector bosons by hadronic jets in proton-antiproton and proton-proton collisions at collider energies

    International Nuclear Information System (INIS)

    Ranft, J.; Ritter, S.

    1980-07-01

    The charge properties of quark jets are studied within a chain decay model for quark jet fragmentation. Using the charge properties of quark jets, charge-charge two-jet cross sections and correlations are defined. In proton-antiproton collisions these correlations show significant structure due to the weak vector bosons W +- and Z 0 . (author)

  15. Interaction particles from the surface of the curved pipeline

    Directory of Open Access Journals (Sweden)

    Vasilevsky Michail

    2017-01-01

    Full Text Available The interaction of the agglomerated fine dust particles from the surface of the rotary pyleprovoda, given deposit formation evaluation. The interaction of large particles to the surface of the rotary pyleprovoda. The analysis of hydrodynamic phenomena in the means of protection against wear.

  16. Biomaterial surface proteomic signature determines interaction with epithelial cells.

    Science.gov (United States)

    Abdallah, Mohamed-Nur; Tran, Simon D; Abughanam, Ghada; Laurenti, Marco; Zuanazzi, David; Mezour, Mohamed A; Xiao, Yizhi; Cerruti, Marta; Siqueira, Walter L; Tamimi, Faleh

    2017-05-01

    Cells interact with biomaterials indirectly through extracellular matrix (ECM) proteins adsorbed onto their surface. Accordingly, it could be hypothesized that the surface proteomic signature of a biomaterial might determine its interaction with cells. Here, we present a surface proteomic approach to test this hypothesis in the specific case of biomaterial-epithelial cell interactions. In particular, we determined the surface proteomic signature of different biomaterials exposed to the ECM of epithelial cells (basal lamina). We revealed that the biomaterial surface chemistry determines the surface proteomic profile, and subsequently the interaction with epithelial cells. In addition, we found that biomaterials with surface chemistries closer to that of percutaneous tissues, such as aminated PMMA and aminated PDLLA, promoted higher selective adsorption of key basal lamina proteins (laminins, nidogen-1) and subsequently improved their interactions with epithelial cells. These findings suggest that mimicking the surface chemistry of natural percutaneous tissues can improve biomaterial-epithelial integration, and thus provide a rationale for the design of improved biomaterial surfaces for skin regeneration and percutaneous medical devices. Failure of most biomaterials originates from the inability to predict and control the influence of their surface properties on biological phenomena, particularly protein adsorption, and cellular behaviour, which subsequently results in unfavourable host response. Here, we introduce a surface-proteomic screening approach using a label-free mass spectrometry technique to decipher the adsorption profile of extracellular matrix (ECM) proteins on different biomaterials, and correlate it with cellular behaviour. We demonstrated that the way a biomaterial selectively interacts with specific ECM proteins of a given tissue seems to determine the interactions between the cells of that tissue and biomaterials. Accordingly, this approach can

  17. Workplace surfaces as resource for social interactions

    NARCIS (Netherlands)

    Vyas, Dhaval; Nijholt, Antinus; Nishida, T.

    2009-01-01

    Space and spatial arrangements play an important role in our everyday social interactions. The way we use and manage our surrounding space is not coincidental, on the contrary, it reflects the way we think, plan and act. Within collaborative contexts, its ability to support social activities makes

  18. Regulating DNA Self-assembly by DNA-Surface Interactions.

    Science.gov (United States)

    Liu, Longfei; Li, Yulin; Wang, Yong; Zheng, Jianwei; Mao, Chengde

    2017-12-14

    DNA self-assembly provides a powerful approach for preparation of nanostructures. It is often studied in bulk solution and involves only DNA-DNA interactions. When confined to surfaces, DNA-surface interactions become an additional, important factor to DNA self-assembly. However, the way in which DNA-surface interactions influence DNA self-assembly is not well studied. In this study, we showed that weak DNA-DNA interactions could be stabilized by DNA-surface interactions to allow large DNA nanostructures to form. In addition, the assembly can be conducted isothermally at room temperature in as little as 5 seconds. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. MODELING THE INTERACTION OF AGROCHEMICALS WITH ENVIRONMENTAL SURFACES: PESTICIDES ON RUTILE AND ORGANO-RUTILE SURFACES

    Science.gov (United States)

    Non-bonded interactions between model pesticides and organo-mineral surfaces have been studied using molecular mechanical conformational calculations and molecular dynamics simulations. The minimum energy conformations and relative binding energies for the interaction of atrazine...

  20. PISCES program plasma-surface interactions research

    International Nuclear Information System (INIS)

    1989-05-01

    This paper discusses the following about the Pisces program: Major objectives of the program; Staff in the PISCES program at UCLA; Highlights in the program; Collaborations with other institutions; PISCES-A facility; PISCES-B facility; Fast scanning Langmuir probe; Omegatron mass spectrometer; Spectroscopic diagnostics; Data acquisition system; Redeposition effect on carbon chemical erosion; Erosion of carbon tokamakium from TFTR; Effect of boron-doping on carbon chemical erosion; Radiation enhanced sublimation of carbon; Surface analysis of TEXTOR titles; Spectroscopic analysis of carbon impurities; Biased limiter and divertor; Biased divertor channel; Gaseous divertor experiments; Presheath profile measurements; Particle transport in CCT tokamak; and Biased divertor experiments in CCT

  1. MODELING THE INTERACTION OF AGROCHEMICALS WITH ENVIRONMENTAL SURFACES

    Science.gov (United States)

    The interactions between agrochemicals and organo-mineral surfaces were studied using molecular mechanical conformational calculations and molecular dynamics simulations. Atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine), 2,4-D (1, 2-dichlorophenoxyacetic acid), and DD...

  2. Asperity interaction in adhesive contact of metallic rough surfaces

    International Nuclear Information System (INIS)

    Sahoo, Prasanta; Banerjee, Atanu

    2005-01-01

    The analysis of adhesive contact of metallic rough surfaces considering the effect of asperity interaction is the subject of this investigation. The micro-contact model of asperity interactions developed by Zhao and Chang (2001 Trans. ASME: J. Tribol. 123 857-64) is combined with the elastic plastic adhesive contact model developed by Chang et al (1988 Trans. ASME: J. Tribol. 110 50-6) to consider the asperity interaction and elastic-plastic deformation in the presence of surface forces simultaneously. The well-established elastic adhesion index and plasticity index are used to consider the different contact conditions. Results show that asperity interaction influences the load-separation behaviour in elastic-plastic adhesive contact of metallic rough surfaces significantly and, in general, adhesion is reduced due to asperity interactions

  3. Plasma–Surface Interactions Under High Heat and Particle Fluxes

    Directory of Open Access Journals (Sweden)

    Gregory De Temmerman

    2013-01-01

    Full Text Available The plasma-surface interactions expected in the divertor of a future fusion reactor are characterized by extreme heat and particle fluxes interacting with the plasma-facing surfaces. Powerful linear plasma generators are used to reproduce the expected plasma conditions and allow plasma-surface interactions studies under those very harsh conditions. While the ion energies on the divertor surfaces of a fusion device are comparable to those used in various plasma-assited deposition and etching techniques, the ion (and energy fluxes are up to four orders of magnitude higher. This large upscale in particle flux maintains the surface under highly non-equilibrium conditions and bring new effects to light, some of which will be described in this paper.

  4. Linear response theory of activated surface diffusion with interacting adsorbates

    Energy Technology Data Exchange (ETDEWEB)

    Marti' nez-Casado, R. [Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ (United Kingdom); Sanz, A.S.; Vega, J.L. [Instituto de Fi' sica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 123, 28006 Madrid (Spain); Rojas-Lorenzo, G. [Instituto Superior de Tecnologi' as y Ciencias Aplicadas, Ave. Salvador Allende, esq. Luaces, 10400 La Habana (Cuba); Instituto de Fi' sica Fundamental, Consejo Superior de Investigaciones Cienti' ficas, Serrano 123, 28006 Madrid (Spain); Miret-Artes, S., E-mail: s.miret@imaff.cfmac.csic.es [Instituto de Fi' sica Fundamental, Consejo Superior de Investigaciones Cienti' ficas, Serrano 123, 28006 Madrid (Spain)

    2010-05-12

    Graphical abstract: Activated surface diffusion with interacting adsorbates is analyzed within the Linear Response Theory framework. The so-called interacting single adsorbate model is justified by means of a two-bath model, where one harmonic bath takes into account the interaction with the surface phonons, while the other one describes the surface coverage, this leading to defining a collisional friction. Here, the corresponding theory is applied to simple systems, such as diffusion on flat surfaces and the frustrated translational motion in a harmonic potential. Classical and quantum closed formulas are obtained. Furthermore, a more realistic problem, such as atomic Na diffusion on the corrugated Cu(0 0 1) surface, is presented and discussed within the classical context as well as within the framework of Kramer's theory. Quantum corrections to the classical results are also analyzed and discussed. - Abstract: Activated surface diffusion with interacting adsorbates is analyzed within the Linear Response Theory framework. The so-called interacting single adsorbate model is justified by means of a two-bath model, where one harmonic bath takes into account the interaction with the surface phonons, while the other one describes the surface coverage, this leading to defining a collisional friction. Here, the corresponding theory is applied to simple systems, such as diffusion on flat surfaces and the frustrated translational motion in a harmonic potential. Classical and quantum closed formulas are obtained. Furthermore, a more realistic problem, such as atomic Na diffusion on the corrugated Cu(0 0 1) surface, is presented and discussed within the classical context as well as within the framework of Kramer's theory. Quantum corrections to the classical results are also analyzed and discussed.

  5. The interaction of water and hydrogen with nickel surfaces

    NARCIS (Netherlands)

    Shan, Junjun

    2009-01-01

    As nickel and platinum are in the same group of the periodic table, the Ni(111) and Pt(111) surfaces may be expected to show similar interaction with water and hydrogen. However in this thesis, we show these interactions for Ni(111) are quite different from those of Pt(111). Moreover, our results

  6. Interactions between acid- and base-functionalized surfaces

    NARCIS (Netherlands)

    Giesbers, M.; Kleijn, J.M.; Cohen Stuart, M.A.

    2002-01-01

    In this paper we present an AFM force study on interactions between chemically modified surfaces. Surfaces with terminal groups of either NH2 or COOH were obtained by chemisorption of a silane-based compound (3-amino-propyltriethoxysilane) on silica or a thiol compound (11-mercapto undecanoic acid)

  7. Electric double layer interactions in bacterial adhesion to surfaces

    NARCIS (Netherlands)

    Poortinga, AT; Norde, W; Busscher, HJ; Bos, R.R.M.

    2002-01-01

    The DLVO (Derjaguin, Landau, Verwey, Overbeek) theory was originally developed to describe interactions between non-biological lyophobic colloids such as polystyrene particles, but is also used to describe bacterial adhesion to surfaces. Despite the differences between the surface of bacteria and

  8. Interactions between kaolinite Al−OH surface and sodium hexametaphosphate

    Energy Technology Data Exchange (ETDEWEB)

    Han, Yonghua, E-mail: hyh19891102@163.com [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Liu, Wenli; Zhou, Jia [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Chen, Jianhua [College of Resources and Metallurgy, Guangxi University, Nanning 530004 (China)

    2016-11-30

    Highlights: • Sodium hexametaphosphate (NaHMP) can adsorb on kaolinite Al−OH terminated (001) surface easily. • The oxygen atoms of hexametaphosphate form strong hydrogen bonds with the hydrogen atoms of kaolinite Al−OH surface. • The electrostatic force is the main interaction between NaHMP and Al−OH surface. • The linear hexaphosphate −[PO{sub 3}]{sub m}− chains adsorb stably than −[HPO{sub 3}]{sub m}− chains. - Abstract: To investigate the dispersion mechanism of sodium hexametaphosphate on kaolinite particles, we simulated the interaction between linear polyphosphate chains and kaolinite Al−OH terminated surface by molecular dynamics, as well as the interaction between the [HPO{sub 4}]{sup 2−} anion and kaolinite Al−OH surface by density functional theory (DFT). The calculated results demonstrate that hexametaphosphate can be adsorbed by the kaolinite Al−OH surface. The oxygen atoms of hexametaphosphate anions may receive many electrons from the Al−OH surface and form hydrogen bonds with the hydrogen atoms of surface hydroxyl groups. Moreover, electrostatic force dominates the interactions between hexametaphosphate anions and kaolinite Al−OH surface. Therefore, after the adsorption of hexametaphosphate on kaolinite Al−OH surface, the kaolinite particles carry more negative charge and the electrostatic repulsion between particles increases. In addition, the adsorption of −[PO{sub 3}]{sub m}− species on the Al−OH surface should be more stable than the adsorption of −[HPO{sub 3}]{sub m}− species.

  9. Interactions of planetary magnetospheres with icy satellite surfaces

    International Nuclear Information System (INIS)

    Cheng, A.F.; Haff, P.K.; Johnson, R.E.; Lanzerotti, L.J.

    1986-01-01

    When natural satellites and ring particles are embedded within magnetospheric plasmas, the charged particles interact with the surfaces of these solid bodies. These interactions have important implications for the surface, the atmosphere of the parent body, and the magnetosphere as a whole. Significant erosion of the surface by sputtering, as well as redeposition of sputter ejecta, can occur over geologic time. The surface can also be chemically modified. Sputter ejecta can make important contributions to the atmosphere; sputtering provides a lower limit to the atmospheric column density even for arbitrarily cold satellite surfaces. Sputter ejecta escaping from the parent body can form extensive neutral clouds within the magnetosphere. Ionization and dissociation within these neutral clouds can be dominant sources of low-energy plasma. The importance of these processes is discussed for the satellites and magnetospheres of Jupiter, Saturn and Uranus

  10. Pycortex: an interactive surface visualizer for fMRI

    Directory of Open Access Journals (Sweden)

    James Shuang Gao

    2015-09-01

    Full Text Available Surface visualizations of fMRI provide a comprehensive view of cortical activity. However, surface visualizations are difficult to generate and most common visualization techniques rely on unnecessary interpolation which limits the fidelity of the resulting maps. Furthermore, it is difficult to understand the relationship between flattened cortical surfaces and the underlying 3D anatomy using tools available currently. To address these problems we have developed pycortex, a Python toolbox for interactive surface mapping and visualization. Pycortex exploits the power of modern graphics cards to sample volumetric data on a per-pixel basis, allowing dense and accurate mapping of the voxel grid across the surface. Anatomical, functional and fiduciary information can be projected onto the cortical surface. The surface can be inflated and flattened interactively, aiding interpretation of the correspondence between the anatomical surface and the flattened cortical sheet. The output of pycortex can be viewed using WebGL, a technology compatible with modern web browsers. This allows complex fMRI surface maps to be distributed broadly online without requiring installation of complex software.

  11. Structures of multidomain proteins adsorbed on hydrophobic interaction chromatography surfaces.

    Science.gov (United States)

    Gospodarek, Adrian M; Sun, Weitong; O'Connell, John P; Fernandez, Erik J

    2014-12-05

    In hydrophobic interaction chromatography (HIC), interactions between buried hydrophobic residues and HIC surfaces can cause conformational changes that interfere with separations and cause yield losses. This paper extends our previous investigations of protein unfolding in HIC chromatography by identifying protein structures on HIC surfaces under denaturing conditions and relating them to solution behavior. The thermal unfolding of three model multidomain proteins on three HIC surfaces of differing hydrophobicities was investigated with hydrogen exchange mass spectrometry (HXMS). The data were analyzed to obtain unfolding rates and Gibbs free energies for unfolding of adsorbed proteins. The melting temperatures of the proteins were lowered, but by different amounts, on the different surfaces. In addition, the structures of the proteins on the chromatographic surfaces were similar to the partially unfolded structures produced in the absence of a surface by temperature as well as by chemical denaturants. Finally, it was found that patterns of residue exposure to solvent on different surfaces at different temperatures can be largely superimposed. These findings suggest that protein unfolding on various HIC surfaces might be quantitatively related to protein unfolding in solution and that details of surface unfolding behavior might be generalized. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. The Character of the Solar Wind, Surface Interactions, and Water

    Science.gov (United States)

    Farrell, William M.

    2011-01-01

    We discuss the key characteristics of the proton-rich solar wind and describe how it may interact with the lunar surface. We suggest that solar wind can be both a source and loss of water/OH related volatiles, and review models showing both possibilities. Energy from the Sun in the form of radiation and solar wind plasma are in constant interaction with the lunar surface. As such, there is a solar-lunar energy connection, where solar energy and matter are continually bombarding the lunar surface, acting at the largest scale to erode the surface at 0.2 Angstroms per year via ion sputtering [1]. Figure 1 illustrates this dynamically Sun-Moon system.

  13. Immobilized enzymes: understanding enzyme - surface interactions at the molecular level.

    Science.gov (United States)

    Hoarau, Marie; Badieyan, Somayesadat; Marsh, E Neil G

    2017-11-22

    Enzymes immobilized on solid supports have important and industrial and medical applications. However, their uses are limited by the significant reductions in activity and stability that often accompany the immobilization process. Here we review recent advances in our understanding of the molecular level interactions between proteins and supporting surfaces that contribute to changes in stability and activity. This understanding has been facilitated by the application of various surface-sensitive spectroscopic techniques that allow the structure and orientation of enzymes at the solid/liquid interface to be probed, often with monolayer sensitivity. An appreciation of the molecular interactions between enzyme and surface support has allowed the surface chemistry and method of enzyme attachement to be fine-tuned such that activity and stability can be greatly enhanced. These advances suggest that a much wider variety of enzymes may eventually be amenable to immobilization as green catalysts.

  14. Electron emission during multicharged ion-metal surface interactions

    International Nuclear Information System (INIS)

    Zeijlmans van Emmichoven, P.A.; Havener, C.C.; Hughes, I.G.; Overbury, S.H.; Robinson, M.T.; Zehner, D.M.; Meyer, F.W.

    1992-01-01

    The electron emission during multicharged ion-metal surface interactions will be discussed. The interactions lead to the emission of a significant number of electrons. Most of these electrons have energies below 30 eV. For incident ions with innershell vacancies the emission of Auger electrons that fill these vacancies has been found to occur mainly below the surface. We will present recently measured electron energy distributions which will be used to discuss the mechanisms that lead to the emission of Auger and of low-energy electrons

  15. Towards a Revised Monte Carlo Neutral Particle Surface Interaction Model

    International Nuclear Information System (INIS)

    Stotler, D.P.

    2005-01-01

    The components of the neutral- and plasma-surface interaction model used in the Monte Carlo neutral transport code DEGAS 2 are reviewed. The idealized surfaces and processes handled by that model are inadequate for accurately simulating neutral transport behavior in present day and future fusion devices. We identify some of the physical processes missing from the model, such as mixed materials and implanted hydrogen, and make some suggestions for improving the model

  16. Improved simulation of groundwater - surface water interaction in catchment models

    Science.gov (United States)

    teklesadik, aklilu; van Griensven, Ann; Anibas, Christian; Huysmans, Marijke

    2016-04-01

    Groundwater storage can have a significant contribution to stream flow, therefore a thorough understanding of the groundwater surface water interaction is of prime important when doing catchment modeling. The aim of this study is to improve the simulation of groundwater - surface water interaction in a catchment model of the upper Zenne River basin located in Belgium. To achieve this objective we used the "Groundwater-Surface water Flow" (GSFLOW) modeling software, which is an integration of the surface water modeling tool "Precipitation and Runoff Modeling system" (PRMS) and the groundwater modeling tool MODFLOW. For this case study, the PRMS model and MODFLOW model were built and calibrated independently. The PRMS upper Zenne River basin model is divided into 84 hydrological response units (HRUs) and is calibrated with flow data at the Tubize gauging station. The spatial discretization of the MODFLOW upper Zenne groundwater flow model consists of 100m grids. Natural groundwater divides and the Brussels-Charleroi canal are used as boundary conditions for the MODFLOW model. The model is calibrated using piezometric data. The GSFLOW results were evaluated against a SWAT model application and field observations of groundwater-surface water interactions along a cross section of the Zenne River and riparian zone. The field observations confirm that there is no exchange of groundwater beyond the Brussel-Charleroi canal and that the interaction at the river bed is relatively low. The results show that there is a significant difference in the groundwater simulations when using GSFLOW versus SWAT. This indicates that the groundwater component representation in the SWAT model could be improved and that a more realistic implementation of the interactions between groundwater and surface water is advisable. This could be achieved by integrating SWAT and MODFLOW.

  17. Dynamic interactions of Leidenfrost droplets on liquid metal surface

    Science.gov (United States)

    Ding, Yujie; Liu, Jing

    2016-09-01

    Leidenfrost dynamic interaction effects of the isopentane droplets on the surface of heated liquid metal were disclosed. Unlike conventional rigid metal, such conductive and deformable liquid metal surface enables the levitating droplets to demonstrate rather abundant and complex dynamics. The Leidenfrost droplets at different diameters present diverse morphologies and behaviors like rotation and oscillation. Depending on the distance between the evaporating droplets, they attract and repulse each other through the curved surfaces beneath them and their vapor flows. With high boiling point up to 2000 °C, liquid metal offers a unique platform for testing the evaporating properties of a wide variety of liquid even solid.

  18. Attractive interaction between an atom and a surface

    International Nuclear Information System (INIS)

    Manson, J.R.; Ritchie, R.H.

    1983-01-01

    Using a general self-energy formalism we examine the interaction between an atom and a surface. Considered in detail are deviations from the Van der Waals force due to recoil and finite velocity of the particle. Calculations for positronium near a metal surface show that for such systems recoil and velocity effects are significant even at very low energies. We also examine the mechanisms for energy exchange with the surface and calculations show that single quantum events do not always dominate the exchange rates. 8 references, 2 figures

  19. SGP Cloud and Land Surface Interaction Campaign (CLASIC): Measurement Platforms

    Energy Technology Data Exchange (ETDEWEB)

    MA Miller; R Avissar; LK Berg; SA Edgerton; ML Fischer; TJ Jackson; B. Kustas; PJ Lamb; G McFarquhar; Q Min; B Schmid; MS Torn; DD Tuner

    2007-06-01

    The Cloud and Land Surface Interaction Campaign (CLASIC) will be conducted from June 8 to June 30, 2007, at the U.S. Department of Energy’s Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) Southern Great Plains (SGP) site. Data will be collected using eight aircraft equipped with a variety of specialized sensors, four specially instrumented surface sites, and two prototype surface radar systems. The architecture of CLASIC includes a high-altitude surveillance aircraft and enhanced vertical thermodynamic and wind profile measurements that will characterize the synoptic scale structure of the clouds and the land surface within the ACRF SGP site. Mesoscale and microscale structures will be sampled with a variety of aircraft, surface, and radar observations. An overview of the measurement platforms that will be used during the CLASIC are described in this report. The coordination of measurements, especially as it relates to aircraft flight plans, will be discussed in the CLASIC Implementation Plan.

  20. Sikorsky interactive graphics surface design/manufacturing system

    Science.gov (United States)

    Robbins, R.

    1975-01-01

    An interactive graphics system conceived to be used in the design, analysis, and manufacturing of aircraft components with free form surfaces was described. In addition to the basic surface definition and viewing capabilities inherent in such a system, numerous other features are present: surface editing, automated smoothing of control curves, variable milling patch boundary definitions, surface intersection definition and viewing, automatic creation of true offset surfaces, digitizer and drafting machine interfaces, and cutter path optimization. Documented costs and time savings of better than six to one are being realized with this system. The system was written in FORTRAN and GSP for use on IBM 2250 CRT's in conjunction with an IBM 370/158 computer.

  1. On the Interaction of Capillary Shapes with Solid Surfaces

    NARCIS (Netherlands)

    Musterd, M.

    2015-01-01

    Control over the interaction of droplets with solid surfaces is commonplace in nature. Famous examples are the water-shedding capabilities of the lotus leaf and the water-harvesting skin of certain types of beetles. To date, this type of control remains a challenge in engineering applications.

  2. The interaction between surface water and groundwater and its ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 125; Issue 7. The interaction between surface water and groundwater and its effect on water quality in the Second Songhua River basin, northeast China. Bing Zhang Xianfang Song Yinghua Zhang Ying Ma Changyuan Tang Lihu Yang Zhong-Liang Wang. Volume ...

  3. Nonlinear interaction of the surface waves at a plasma boundary

    International Nuclear Information System (INIS)

    Dolgopolov, V.V.; El-Naggar, I.A.; Hussein, A.M.; Khalil, Sh.M.

    1976-01-01

    Amplitudes of electromagnetic waves with combination frequencies, radiating from the plasma boundary due to nonlinear interaction of the surface waves, have been found. Previous papers on this subject did not take into account that the tangential components of the electric field of waves with combination frequencies were discontinuous at the plasma boundary. (Auth.)

  4. Interaction of β-sheet folds with a gold surface.

    Directory of Open Access Journals (Sweden)

    Martin Hoefling

    Full Text Available The adsorption of proteins on inorganic surfaces is of fundamental biological importance. Further, biomedical and nanotechnological applications increasingly use interfaces between inorganic material and polypeptides. Yet, the underlying adsorption mechanism of polypeptides on surfaces is not well understood and experimentally difficult to analyze. Therefore, we investigate here the interactions of polypeptides with a gold(111 surface using computational molecular dynamics (MD simulations with a polarizable gold model in explicit water. Our focus in this paper is the investigation of the interaction of polypeptides with β-sheet folds. First, we concentrate on a β-sheet forming model peptide. Second, we investigate the interactions of two domains with high β-sheet content of the biologically important extracellular matrix protein fibronectin (FN. We find that adsorption occurs in a stepwise mechanism both for the model peptide and the protein. The positively charged amino acid Arg facilitates the initial contact formation between protein and gold surface. Our results suggest that an effective gold-binding surface patch is overall uncharged, but contains Arg for contact initiation. The polypeptides do not unfold on the gold surface within the simulation time. However, for the two FN domains, the relative domain-domain orientation changes. The observation of a very fast and strong adsorption indicates that in a biological matrix, no bare gold surfaces will be present. Hence, the bioactivity of gold surfaces (like bare gold nanoparticles will critically depend on the history of particle administration and the proteins present during initial contact between gold and biological material. Further, gold particles may act as seeds for protein aggregation. Structural re-organization and protein aggregation are potentially of immunological importance.

  5. Self-energies and the interactions of particles with surfaces

    International Nuclear Information System (INIS)

    Manson, J.R.; Ritchie, R.H.; Echenique, P.M.; Gras-Marti, A.

    1987-01-01

    We have in this paper reviewed the method of treating many-body problems by means of an effective interaction self-energy. We have developed an alternatvie approach to the self-energy which is simpler and more straight-forward than standard methods, and we have illustrated its use with two examples of a charge interacting with a metal surface. In each case the self-energy produces the classical image potential together with corrections due to quantum mechanical effects. This method has also been successfully applied to the problem of an atom interacting with a surface. Corrections to the Van der Waals dispersion force are obtained, and via the non-conservative imaginary parts to /summation//sub i/(z) we discuss transition rates and energy exchange. 14 refs., 1 fig

  6. Cluster-surface interaction: from soft landing to implantation

    DEFF Research Database (Denmark)

    Popok, Vladimir; Barke, Ingo; Campbell, Eleanor E.B.

    2011-01-01

    The current paper presents a state-of-the-art review in the field of interaction of atomic and molecular clusters with solids. We do not attempt to overview the entire broad field but rather concentrate on impact phenomena: how the physics of the cluster-surface interaction depends on the kinetic...... for utilisation in optics and electronics, as magnetic media and catalysts, in nanobiology and nanomedicine. We pay considerable attention to phenomena occurring on impact of clusters with increased kinetic energies. In particular, we discuss the physics of the intermediate regime between deposition...... for efficient smoothing of surfaces on the macroscopic scale. Several examples of successful applications of the cluster beam technique for polishing of surfaces are given. We also discuss how the physical sputtering can be combined with reactive accelerated cluster erosion. The latter can be an efficient tool...

  7. Photoresponsive peptide azobenzene conjugates that specifically interact with platinum surfaces

    Science.gov (United States)

    Dinçer, S.; Tamerler, C.; Sarıkaya, M.; Pişkin, E.

    2008-05-01

    The aim of this study is to prepare photoresponsive peptide-azobenzene compounds which interacts with platinum surfaces specifically, in order to create smart surfaces for further novel applications in design of smart biosensors and array platforms. Here, a water-soluble azobenzene molecule, 4-hydroxyazo benzene,4-sulfonic acid was synthesized by diazo coupling reaction. A platinum-specific peptide, originally selected by a phage display technique was chemically synthesized/purchased, and conjugated with the azobenzene compound activated with carbonyldiimidazole. Both azobenzene and its conjugate were characterized (including photoresponsive properties) by FTIR, NMR, and UV-spectrophotometer. The yield of conjugation reaction estimated by ninhydrin assay was about 65%. Peptide incorporation did not restrict the light-sensitivity of azobenzene. Adsorption of both the peptide and its azobenzene conjugate was followed by Quartz Crystal Microbalance (QCM) system. The kinetic evaluations exhibited that both molecules interact platinum surfaces, quite rapidly and strongly.

  8. Multi-scale surface-groundwater interactions: Processes and Implications

    Science.gov (United States)

    Packman, A. I.; Harvey, J. W.; Worman, A.; Cardenas, M. B.; Schumer, R.; Jerolmack, D. J.; Tank, J. L.; Stonedahl, S. H.

    2009-05-01

    Site-based investigations of stream-subsurface interactions normally focus on a limited range of spatial scales - typically either very shallow subsurface flows in the hyporheic zone, or much larger scale surface- groundwater interactions - but subsurface flows are linked across this entire continuum. Broad, multi-scale surface-groundwater interactions produce complex patterns in porewater flows, and interfacial fluxes do not average in a simple fashion because of the competitive effects of flows induced at different scales. For example, reach-scale stream-groundwater interactions produce sequences of gaining and losing reaches that can either suppress or enhance local-scale hyporheic exchange. Many individual topographic features also produce long power-law tails in surface residence time distributions, and the duration of these tails is greatly extended by interactions over a wide range of spatial scales. Simultaneous sediment transport and landscape evolution further complicates the analysis of porewater flow dynamics in rivers. Finally, inhomogeneity in important biogeochemical processes, particularly microbial processes that are stimulated near the sediment- water interface, leads to a great degree of non-linearity in chemical transformation rates in stream channels. This high degree of complexity in fluvial systems requires that careful approaches be used to extend local observations of hyporheic exchange and associated nutrient, carbon, and contaminant transformations to larger spatial scales. It is important to recognize that conventional advection-dispersion models are not expected to apply, and instead anomalous transport models must be used. Unfortunately, no generally applicable model is available for stream-groundwater interactions at the present time. Alternative approaches for modeling conservative and reactive transport will be discussed, and a strategy articulated for coping with the complexity of coupled surface-subsurface dynamics in fluvial

  9. Surface interactions involved in flashover with high density electronegative gases.

    Energy Technology Data Exchange (ETDEWEB)

    Hodge, Keith Conquest; Warne, Larry Kevin; Jorgenson, Roy Eberhardt; Wallace, Zachariah Red; Lehr, Jane Marie

    2010-01-01

    This report examines the interactions involved with flashover along a surface in high density electronegative gases. The focus is on fast ionization processes rather than the later time ionic drift or thermalization of the discharge. A kinetic simulation of the gas and surface is used to examine electron multiplication and includes gas collision, excitation and ionization, and attachment processes, gas photoionization and surface photoemission processes, as well as surface attachment. These rates are then used in a 1.5D fluid ionization wave (streamer) model to study streamer propagation with and without the surface in air and in SF6. The 1.5D model therefore includes rates for all these processes. To get a better estimate for the behavior of the radius we have studied radial expansion of the streamer in air and in SF6. The focus of the modeling is on voltage and field level changes (with and without a surface) rather than secondary effects, such as, velocities or changes in discharge path. An experiment has been set up to carry out measurements of threshold voltages, streamer velocities, and other discharge characteristics. This setup includes both electrical and photographic diagnostics (streak and framing cameras). We have observed little change in critical field levels (where avalanche multiplication sets in) in the gas alone versus with the surface. Comparisons between model calculations and experimental measurements are in agreement with this. We have examined streamer sustaining fields (field which maintains ionization wave propagation) in the gas and on the surface. Agreement of the gas levels with available literature is good and agreement between experiment and calculation is good also. Model calculations do not indicate much difference between the gas alone versus the surface levels. Experiments have identified differences in velocity between streamers on the surface and in the gas alone (the surface values being larger).

  10. Interactions of Candida albicans with host epithelial surfaces

    Directory of Open Access Journals (Sweden)

    David W. Williams

    2013-10-01

    Full Text Available Candida albicans is an opportunistic, fungal pathogen of humans that frequently causes superficial infections of oral and vaginal mucosal surfaces of debilitated and susceptible individuals. The organism is however, commonly encountered as a commensal in healthy individuals where it is a component of the normal microflora. The key determinant in the type of relationship that Candida has with its host is how it interacts with the epithelial surface it colonises. A delicate balance clearly exists between the potentially damaging effects of Candida virulence factors and the nature of the immune response elicited by the host. Frequently, it is changes in host factors that lead to Candida seemingly changing from a commensal to pathogenic existence. However, given the often reported heterogeneity in morphological and biochemical factors that exist between Candida species and indeed strains of C. albicans, it may also be the fact that colonising strains differ in the way they exploit resources to allow persistence at mucosal surfaces and as a consequence this too may affect the way Candida interacts with epithelial cells. The aim of this review is to provide an overview of some of the possible interactions that may occur between C. albicans and host epithelial surfaces that may in turn dictate whether Candida removal, its commensal persistence or infection follows.

  11. Biological Surface Adsorption Index of Nanomaterials: Modelling Surface Interactions of Nanomaterials with Biomolecules.

    Science.gov (United States)

    Chen, Ran; Riviere, Jim E

    2017-01-01

    Quantitative analysis of the interactions between nanomaterials and their surrounding environment is crucial for safety evaluation in the application of nanotechnology as well as its development and standardization. In this chapter, we demonstrate the importance of the adsorption of surrounding molecules onto the surface of nanomaterials by forming biocorona and thus impact the bio-identity and fate of those materials. We illustrate the key factors including various physical forces in determining the interaction happening at bio-nano interfaces. We further discuss the mathematical endeavors in explaining and predicting the adsorption phenomena, and propose a new statistics-based surface adsorption model, the Biological Surface Adsorption Index (BSAI), to quantitatively analyze the interaction profile of surface adsorption of a large group of small organic molecules onto nanomaterials with varying surface physicochemical properties, first employing five descriptors representing the surface energy profile of the nanomaterials, then further incorporating traditional semi-empirical adsorption models to address concentration effects of solutes. These Advancements in surface adsorption modelling showed a promising development in the application of quantitative predictive models in biological applications, nanomedicine, and environmental safety assessment of nanomaterials.

  12. Interactions between endothelial progenitor cells (EPC) and titanium implant surfaces.

    Science.gov (United States)

    Ziebart, Thomas; Schnell, Anne; Walter, Christian; Kämmerer, Peer W; Pabst, Andreas; Lehmann, Karl M; Ziebart, Johanna; Klein, Marc O; Al-Nawas, Bilal

    2013-01-01

    Endothelial cells play an important role in peri-implant angiogenesis during early bone formation. Therefore, interactions between endothelial progenitor cells (EPCs) and titanium dental implant surfaces are of crucial interest. The aim of our in vitro study was to investigate the reactions of EPCs in contact with different commercially available implant surfaces. EPCs from buffy coats were isolated by Ficoll density gradient separation. After cell differentiation, EPC were cultured for a period of 7 days on different titanium surfaces. The test surfaces varied in roughness and hydrophilicity: acid-etched (A), sand-blasted-blasted and acid-etched (SLA), hydrophilic A (modA), and hydrophilic SLA (modSLA). Plastic and fibronectin-coated plastic surfaces served as controls. Cell numbers and morphology were analyzed by confocal laser scanning microscopy. Secretion of vascular endothelial growth factor (VEGF)-A was measured by enzyme-linked immunosorbent assay and expressions of iNOS and eNOS were investigated by real-time polymerase chain reaction. Cell numbers were higher in the control groups compared to the cells of titanium surfaces. Initially, hydrophilic titanium surfaces (modA and modSLA) showed lower cell numbers than hydrophobic surfaces (A and SLA). After 7 days smoother surfaces (A and modA) showed increased cell numbers compared to rougher surfaces (SLA and modSLA). Cell morphology of A, modA, and control surfaces was characterized by a multitude of pseudopodia and planar cell soma architecture. SLA and modSLA promoted small and plump cell soma with little quantity of pseudopodia. The lowest VEGF level was measured on A, the highest on modSLA. The highest eNOS and iNOS expressions were found on modA surfaces. The results of this study demonstrate that biological behaviors of EPCs can be influenced by different surfaces. The modSLA surface promotes an undifferentiated phenotype of EPCs that has the ability to secrete growth factors in great quantities. In

  13. On the interaction between ocean surface waves and seamounts

    Science.gov (United States)

    Sosa, Jeison; Cavaleri, Luigi; Portilla-Yandún, Jesús

    2017-12-01

    Of the many topographic features, more specifically seamounts, that are ubiquitous in the ocean floor, we focus our attention on those with relatively shallow summits that can interact with wind-generated surface waves. Among these, especially relatively long waves crossing the oceans (swells) and stormy seas are able to affect the water column up to a considerable depth and therefore interact with these deep-sea features. We quantify this interaction through numerical experiments using a numerical wave model (SWAN), in which a simply shaped seamount is exposed to waves of different length. The results show a strong interaction that leads to significant changes in the wave field, creating wake zones and regions of large wave amplification. This is then exemplified in a practical case where we analyze the interaction of more realistic sea conditions with a very shallow rock in the Yellow Sea. Potentially important for navigation and erosion processes, mutatis mutandis, these results are also indicative of possible interactions with emerged islands and sand banks in shelf seas.

  14. Interactive system for quick modeling of aircraft surfaces

    Science.gov (United States)

    Mudur, S. P.; Khandekar, Dilip R.

    1990-08-01

    The precise specification of surface geometry of an aircraft is one of the most important and major activities inits design. An initial design, defined by the fundamental requirements, is iteratively analysed and modified till a satisfactory configuration is obtained. Very often in the early stages the need to rapidly make modifications to the geometry for immediate analysis overrides the stringency of smoothness and correctness ofthe surfaces. This paper describes the design of an interactive system which enables the designer to quickly specify the surface geometry and to modify it easily and rapidly. In particular, the software engineering aspects are emphasized. The system uses B-splines for the representation of complex geometry. Surfaces of revolution, required to model certain parts ofthe aircraft, and other simple geometric primitives are also supported. Apart from the usual modeller facilities, features such as camber, twist and form constraints such as tangent or curvature control at a point, etc., are also provided. The system enables easy input and rapid editing of geomeiry through the use of a number of innovative concepts which aim at simplifying and speeding up the man-machine interaction. Multiple window display of entities, augmented by plots of curvature, cross sections etc. provide the visualization tool necessary to assist the designer in decision making.

  15. The esa earth explorer land surface processes and interactions mission

    Science.gov (United States)

    Labandibar, Jean-Yves; Jubineau, Franck; Silvestrin, Pierluigi; Del Bello, Umberto

    2017-11-01

    The European Space Agency (ESA) is defining candidate missions for Earth Observation. In the class of the Earth Explorer missions, dedicated to research and pre-operational demonstration, the Land Surface Processes and Interactions Mission (LSPIM) will acquire the accurate quantitative measurements needed to improve our understanding of the nature and evolution of biosphere-atmosphere interactions and to contribute significantly to a solution of the scaling problems for energy, water and carbon fluxes at the Earth's surface. The mission is intended to provide detailed observations of the surface of the Earth and to collect data related to ecosystem processes and radiation balance. It is also intended to address a range of issues important for environmental monitoring, renewable resources assessment and climate models. The mission involves a dedicated maneuvering satellite which provides multi-directional observations for systematic measurement of Land Surface BRDF (BiDirectional Reflectance Distribution Function) of selected sites on Earth. The satellite carries an optical payload : PRISM (Processes Research by an Imaging Space Mission), a multispectral imager providing reasonably high spatial resolution images (50 m over 50 km swath) in the whole optical spectral domain (from 450 nm to 2.35 μm with a resolution close to 10 nm, and two thermal bands from 8.1 to 9.1 μm). This paper presents the results of the Phase A study awarded by ESA, led by ALCATEL Space Industries and concerning the design of LSPIM.

  16. Interaction of deuterium plasma with pre-nitrided tungsten surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Liang

    2016-06-15

    DE027289820Nitrogen (N{sub 2}) has been established as an optimal choice as seeding species to control the divertor heat load in ASDEX Upgrade. Based on a series of dedicated laboratory experiments, the present work is devoted to unravel the underlying physics of the interaction of W surfaces with N{sub 2}-seeded plasmas with respect to D retention in W, i.e., to answer ''how should the presence of N in W surfaces affect the hydrogen isotope retention in W after plasma loadings?''. Treated in a well-defined ECR plasma source (PlaQ) in Max-Planck-Institut fuer Plasmaphysik (IPP, Garching), the experiments in this thesis were performed under the following strategy. Namely, the interaction processes between W surfaces with mixed plasma was split into two major steps. Step one is the development and characterization of an appropriate model system for N-containing W layers and step two is the interaction of D plasmas with these model systems. As a first step, a model system for W:N layers formed at W surfaces during or after N{sub 2} seeding in fusion devices is established. By either N implantation into pure W surfaces or sputter-deposition of WN{sub x} films, two different W:N layers were produced. Different characterization techniques, such as XPS, RBS, NRA and TPD, were employed to characterize of these two different W:N layers, i.e., the implantation range of N into W surfaces, the diffusion of N in W, the determination of the N amount and the decomposition temperature of W:N layers. All the results from different techniques were cross-checked with each other, which allowed a reliable N content determination and its evolution during the consecutive D implantations. Based on these characterizations, sputter-deposited WN{sub x} films and N-implanted W surfaces under certain production conditions were selected for further investigation in the following D implantations. The second and main part of the experiments covers the exposure of

  17. Anomalous water dynamics at surfaces and interfaces: synergistic effects of confinement and surface interactions

    Science.gov (United States)

    Biswas, Rajib; Bagchi, Biman

    2018-01-01

    In nature, water is often found in contact with surfaces that are extended on the scale of molecule size but small on a macroscopic scale. Examples include lipid bilayers and reverse micelles as well as biomolecules like proteins, DNA and zeolites, to name a few. While the presence of surfaces and interfaces interrupts the continuous hydrogen bond network of liquid water, confinement on a mesoscopic scale introduces new features. Even when extended on a molecular scale, natural and biological surfaces often have features (like charge, hydrophobicity) that vary on the scale of the molecular diameter of water. As a result, many new and exotic features, which are not seen in the bulk, appear in the dynamics of water close to the surface. These different behaviors bear the signature of both water–surface interactions and of confinement. In other words, the altered properties are the result of the synergistic effects of surface–water interactions and confinement. Ultrafast spectroscopy, theoretical modeling and computer simulations together form powerful synergistic approaches towards an understanding of the properties of confined water in such systems as nanocavities, reverse micelles (RMs), water inside and outside biomolecules like proteins and DNA, and also between two hydrophobic walls. We shall review the experimental results and place them in the context of theory and simulations. For water confined within RMs, we discuss the possible interference effects propagating from opposite surfaces. Similar interference is found to give rise to an effective attractive force between two hydrophobic surfaces immersed and kept fixed at a separation of d, with the force showing an exponential dependence on this distance. For protein and DNA hydration, we shall examine a multitude of timescales that arise from frustration effects due to the inherent heterogeneity of these surfaces. We pay particular attention to the role of orientational correlations and modification of

  18. Interpreting the probe-surface interaction of surface measuring instruments, or what is a surface?

    Science.gov (United States)

    Leach, Richard; Weckenmann, Albert; Coupland, Jeremy; Hartmann, Wito

    2014-09-01

    When using dimensional measuring instruments it is assumed that there is a property of the object, which we call surface, that is present before during and after the measurement, i.e. the surface is a fundamental property of an object that can, by appropriate means, be used to measure geometry. This paper will attempt to show that the fundamental property ‘surface’ does not exist in any simple form and that all the information we can have about a surface is the measurement data, which will include measurement uncertainty. Measurement data, or what will be referred to as the measured surface, is all that really exists. In this paper the basic physical differences between mechanically, electromagnetically and electrically measured surfaces are highlighted and discussed and accompanied by measurement results on a roughness artefact.

  19. Interpreting the probe-surface interaction of surface measuring instruments, or what is a surface?

    International Nuclear Information System (INIS)

    Leach, Richard; Weckenmann, Albert; Hartmann, Wito; Coupland, Jeremy

    2014-01-01

    When using dimensional measuring instruments it is assumed that there is a property of the object, which we call surface, that is present before during and after the measurement, i.e. the surface is a fundamental property of an object that can, by appropriate means, be used to measure geometry. This paper will attempt to show that the fundamental property ‘surface’ does not exist in any simple form and that all the information we can have about a surface is the measurement data, which will include measurement uncertainty. Measurement data, or what will be referred to as the measured surface, is all that really exists. In this paper the basic physical differences between mechanically, electromagnetically and electrically measured surfaces are highlighted and discussed and accompanied by measurement results on a roughness artefact. (paper)

  20. Turbulent flow over an interactive alternating land-water surface

    Science.gov (United States)

    Van Heerwaarden, C.; Mellado, J. P.

    2014-12-01

    The alternating land-water surface is a challenging surface to represent accurately in weather and climate models, but it is of great importance for the surface energy balance in polar regions. The complexity of this surface lies in the fact that secondary circulations, which form at the boundary of water and land, interact strongly with the surface energy balance. Due to its large heat capacity, the water temperature adapts slowly to the flow, thus the properties of the atmosphere determine the uptake of energy from the water. In order to study this complex system in a simpler way, retaining only the most essential physics, we have simplified the full surface energy balance including radiation. We have derived a boundary condition that mimics the full balance and can be formulated as a so-called Robin boundary condition: a linear combination of Dirichlet (fixed temperature) and Neumann (fixed temperature gradient) ones. By spatially varying the coefficients, we are able to express land and water using this boundary condition. We have done a series of direct numerical simulations in which we generate artificial land-water patterns from noise created from a Gaussian spectrum centered around a dominant wave number. This method creates realistic random patterns, but we are still in control of the length scales. We show that the system can manifest itself in three regimes: micro-, meso- and macro-scale. In the micro-scale, we find perfect mixing of the near-surface atmosphere that results in identical air properties over water and land. In the meso-scale, secondary circulations alter the heat exchange considerably by advecting air between land and water. In addition, they bring the surface temperature of the land closer to that of the air, thereby modulating the energy loss due to outgoing longwave radiation. In the macro-scale regime, the flow over land and water become independent of each other and only the large scale forcings determine the energy balance.

  1. Including Finite Surface Span Effects in Empirical Jet-Surface Interaction Noise Models

    Science.gov (United States)

    Brown, Clifford A.

    2016-01-01

    The effect of finite span on the jet-surface interaction noise source and the jet mixing noise shielding and reflection effects is considered using recently acquired experimental data. First, the experimental setup and resulting data are presented with particular attention to the role of surface span on far-field noise. These effects are then included in existing empirical models that have previously assumed that all surfaces are semi-infinite. This extended abstract briefly describes the experimental setup and data leaving the empirical modeling aspects for the final paper.

  2. Foreword: In situ gas surface interactions: approaching realistic conditions

    Science.gov (United States)

    Lundgren, Edvin; Over, Herbert

    2008-03-01

    This special issue is devoted to the application of in situ surface-sensitive techniques in the elucidation of catalysed reactions at (model) catalyst surfaces. Both reaction intermediates and the nature of the catalytically active phase are the targets of these investigations. In situ surface science techniques are also used to study the interaction of water with surfaces under realistic conditions. Since 80% of all technical chemicals are manufactured by utilizing (heterogeneous) catalysis, scientific understanding and technological development of catalysis are of central practical importance in modern society [1]. Heterogeneously catalysed reactions take place at the gas/solid interface. Therefore one of the major topics in surface chemistry and physics is closely related to heterogeneous catalysis, with the aim of developing novel catalysts and to improve catalysts' performances on the basis of atomic scale based knowledge. Despite the economical and environmental rewards—if such a goal is achieved—and despite 40 years of intensive research, practical catalysis is still safely in a black box: the reactivity and selectivity of a catalyst are commercially still optimized on a trial and error basis, applying the high throughput screening approach. The reason for this discrepancy between ambition and reality lies in the inherent complexity of the catalytic system, consisting of the working catalyst and the interaction of the catalyst with the reactant mixture. Practical (solid) catalysts consist of metal or oxide nanoparticles which are dispersed and stabilized on a support and which may be promoted by means of additives. These particles catalyse a reaction in pressures as high as 100 bar. Practical catalysis is in general considered to be far too complex for gaining atomic-scale understanding of the mechanism of the catalysed reaction of an industrial catalyst during its operation. Therefore it has been necessary to introduce idealization and simplification of

  3. Surface modification of hydrophobic polymers for improvement of endothelial cell-surface interactions

    NARCIS (Netherlands)

    Dekker, A.; Dekker, A.; Reitsma, K.; Beugeling, T.; Beugeling, T.; Bantjes, A.; Bantjes, A.; Feijen, Jan; Kirkpatrick, C.J.; van Aken, W.G.

    1992-01-01

    The aim of this study is to improve the interaction of endothelial cells with polymers used in vascular prostheses. Polytetrafluoroethylene (PTFE; Teflon) films were treated by means of nitrogen and oxygen plasmas. Depending on the plasma exposure time, modified PTFE surfaces showed water-contact

  4. Plasma surface interactions in Q-enhanced mirror systems

    International Nuclear Information System (INIS)

    Post, R.F.

    1978-01-01

    Two approaches to enhancement of the Q (energy gain) factor of mirror systems are under study at Livermore. These include the Tandem Mirror and the Field Reversed Mirror. Both of these new ideas preserve features of conventional mirror systems as far as plasma-wall interactions are concerned. Specifically in both approaches field lines exit from the ends of the system and impinge on walls located at a distance from the confinement chamber. It is possible to predict some aspects of the plasma/surface interactions of TM and FRM systems from experience obtained in the Livermore 2XIIB experiment. In particular, as observed in 2XIIB, effective isolation of the plasma from thermal contact with the ends owing to the development of sheath-like regions is to be expected. Studies presently underway directed toward still further enhancing the decoupling of the plasma from the effects of plasma surface interactions at the walls will be discussed, with particular reference to the problem of minimizing the effects of refluxing secondary electrons produced by plasma impact on the end walls

  5. Spectral studies of Lanthanide interactions with membrane surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Karukstis, K.K.; Kao, M.Y.; Savin, D.A.; Bittker, R.A.; Kaphengst, K.J.; Emetarom, C.M.; Naito, N.R.; Takamoto, D.Y. [Harvey Mudd College, Claremont, CA (United States)

    1995-03-23

    We have monitored the interactions of the series of trivalent lanthanide cations with the thylakoid membrane surface of spinach chloroplasts using two complementary spectral techniques. Measurements of the fluorescence emission of the extrinsic probe 2-p-toluidinonaphthalene-6-sulfonate (TNS) and the absorbance of the intrinsic chromophore chlorophyll provide two sensitive means of characterizing the dependence of the cation-membrane interaction on the nature of the cation. In these systems, added lanthanide cations adsorb onto the membrane surface to neutralize exposed segments of membrane-embedded protein complexes. The lanthanide-induced charge neutralization increases the proximity of added TNS anion to the membrane surface as evidenced by variations in the TNS fluorescence level and wavelength of maximum emission. Our results reveal a strong dependence of TNS fluorescence parameters on both lanthanide size and total orbital angular momentum L value. Lanthanides with greater charge density (small size and/or low L value) enhance the TNS fluorescence level to a greater extent. A possible origin for the lanthanide-dependent TNS fluorescence levels is suggested in terms of a heterogeneity in the number and type of TNS binding sites. The data are consistent with the proposal that larger lanthanides with smaller enthalpies of hydration induce more significant membrane appression. 59 refs., 9 figs., 2 tabs.

  6. The interaction of carbon monoxide with model astrophysical surfaces.

    Science.gov (United States)

    Collings, Mark P; Dever, John W; McCoustra, Martin R S

    2014-02-28

    Carbon monoxide (CO) is an important component of the icy mantles that accrete on interstellar dust grains. To develop a better understanding of the physicochemical basis of its infrared spectroscopy, we have studied the interaction of submonolayer coverages of CO with the surface of films of other astrophysically relevant species--(13)CO, carbon dioxide (CO2), ammonia (NH3), methanol (CH3OH) and water (H2O)--under ultrahigh vacuum and cryogenic (10 K) conditions using reflection-absorption infrared spectroscopy (RAIRS). In support of these measurements, we have performed ab initio calculations of gas phase dimer complexes, and made comparisons to experimental results of gas phase and matrix isolated complexes, which are extensively reported in the literature. The interaction of CO can be categorised as occurring via the C atom (C(CO) bonded), the O atom (O(CO) bonded) or in a π-bonded configuration. The C(CO) configuration is characterised by a blue shifted C≡O stretch frequency, and is observed for CO adsorbed on (13)CO, CO2 and H2O surfaces. From the absence of such a feature from the spectra of CO adsorbed on CH3OH it can be concluded that the dangling OH bonds required for this adsorption configuration are not present at the surface of the CH3OH film.

  7. Cell/surface interactions on laser micro-textured titanium-coated silicon surfaces.

    Science.gov (United States)

    Mwenifumbo, Steven; Li, Mingwei; Chen, Jianbo; Beye, Aboubaker; Soboyejo, Wolé

    2007-01-01

    This paper examines the effects of nano-scale titanium coatings, and micro-groove/micro-grid patterns on cell/surface interactions on silicon surfaces. The nature of the cellular attachment and adhesion to the coated/uncoated micro-textured surfaces was elucidated by the visualization of the cells and relevant cytoskeletal & focal adhesion proteins through scanning electron microscopy and immunofluorescence staining. Increased cell spreading and proliferation rates are observed on surfaces with 50 nm thick Ti coatings. The micro-groove geometries have been shown to promote contact guidance, which leads to reduced scar tissue formation. In contrast, smooth surfaces result in random cell orientations and the increased possibility of scar tissue formation. Immunofluorescence cell staining experiments also reveal that the actin stress fibers are aligned along the groove dimensions, with discrete focal adhesions occurring along the ridges, within the grooves and at the ends of the cell extensions. The implications of the observed cell/surface interactions are discussed for possible applications of silicon in implantable biomedical systems.

  8. Interaction of stress and phase transformations during thermochemical surface engineering

    DEFF Research Database (Denmark)

    Jespersen, Freja Nygaard

    dissolution. The present project is devoted to understanding the mutual interaction of stresses and phase transformations during thermochemical surface engineering by combining numerical modelling with experimental materials science. The modelling was done by combining solid mechanics with thermodynamics...... by chromium atoms, and the effect of composition-induced stress on surface concentration and diffusive flux. The effect of plasticity was also included. Temperature and concentration dependencies of mechanical and diffusion material properties were studied, and the effect of incorporation in the model...... examined. The effect of pre-stressing the sample was also tested, to investigate the effects of a residual stress-state that might be present from processing of the metal specimen. Controlled thermochemical treatment of austenitic stainless steel was investigated experimentally by in-diffusion of nitrogen...

  9. Scattering function for a model of interacting surfaces

    International Nuclear Information System (INIS)

    Colangelo, P.; Gonnella, G.; Maritan, A.

    1993-01-01

    The two-point correlation function of an ensemble of interacting closed self-avoiding surfaces on a cubic lattice is analyzed in the disordered phase, which corresponds to the paramagnetic region in a related spin formulation. Mean-field theory and Monte Carlo simulations predict the existence of a disorder line which corresponds to a transition from an exponential decay to an oscillatory damped behavior of the two-point correlation function. The relevance of the results for the description of amphiphilic systems in a microemulsion phase is discussed. The scattering function is also calculated for a bicontinuous phase coexisting with the paramagnetic phase

  10. Surface water - groundwater interactions at different spatial and temporal scales

    DEFF Research Database (Denmark)

    Sebök, Éva

    As there is a growing demand for the protection and optimal management of both the surface water and groundwater resources, the understanding of their exchange processes is of great importance. This PhD study aimed at describing the natural spatial and temporal variability of these interactions...... detected large spatial variability in SWI temperatures with scattered high-discharge sites in a stream and also in a lake where discharge fluxes were estimated by vertical temperature profiles and seepage meter measurements. On the kilometre scale DTS indicated less spatial variability in streambed...

  11. Nuclear Fusion Research Understanding Plasma-Surface Interactions

    CERN Document Server

    Clark, Robert E.H

    2005-01-01

    It became clear in the early days of fusion research that the effects of the containment vessel (erosion of "impurities") degrade the overall fusion plasma performance. Progress in controlled nuclear fusion research over the last decade has led to magnetically confined plasmas that, in turn, are sufficiently powerful to damage the vessel structures over its lifetime. This book reviews current understanding and concepts to deal with this remaining critical design issue for fusion reactors. It reviews both progress and open questions, largely in terms of available and sought-after plasma-surface interaction data and atomic/molecular data related to these "plasma edge" issues.

  12. Interaction of slow highly charged ions with surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Aumayr, F. [Technische Universitaet Wien (Austria)

    1994-12-31

    A review will be presented on recent investigations concerning the interaction of slow ({le} 10{sup 6} m/s) ions in high charge states approaching a clean metal surface. Detailed information on the generation and decay of transiently formed multiply excited {open_quotes}hollow atoms{close_quotes} can be gained from the measurement of total yields and energy distributions of emitted electrons and, in particular, from the electron emission statistics. By comparing measured results with model calculations based on a recently extended classical over-barrier approach, different sources for the observed electron emission can be identified: autoionisation of the multiply excited hollow atoms on their way toward the surface; promotion above the vacuum barrier of electrons previously captured by the projectile, due to their self- and image-charge screening near the surface; `peeling-off` of electrons still bound in highly excited projectile states at the moment of surface impact, and finally; electron emission due to final subsurface de-excitation.

  13. Surface modification for interaction study with bacteria and preosteoblast cells

    Science.gov (United States)

    Song, Qing

    Surface modification plays a pivotal role in bioengineering. Polymer coatings can provide biocompatibility and biofunctionalities to biomaterials through surface modification. In this dissertation, initiated chemical vapor deposition (iCVD) was utilized to coat two-dimensional (2D) and three-dimensional (3D) substrates with differently charged polyelectrolytes in order to generate antimicrobial and osteocompatible biomaterials. ICVD is a modified CVD technique that enables surface modification in an all-dry condition without substrate damage and solvent contamination. The free-radical polymerization allows the vinyl polymers to conformally coat on various micro- and nano-structured substrates and maintains the delicate structure of the functional groups. The vapor deposition of polycations provided antimicrobial activity to planar and porous substrates through destroying the negatively charged bacterial membrane and brought about high contact-killing efficiency (99.99%) against Gram-positive Bacillus subtilis and Gram-negative Escherichia coli. Additionally, the polyampholytes synthesized by iCVD exhibited excellent antifouling performance against the adhesion of Gram-positive Listeria innocua and Gram-negative E. coli in phosphate buffered saline (PBS). Their antifouling activities were attributed to the electrostatic interaction and hydration layers that served as physical and energetic barriers to prevent bacterial adhesion. The contact-killing and antifouling polymers synthesized by iCVD can be applied to surface modification of food processing equipment and medical devices with the aim of reducing foodborne diseases and medical infections. Moreover, the charged polyelectrolyte modified 2D polystyrene surfaces displayed good osteocompatibility and enhanced osteogenesis of preosteoblast cells than the un-modified polystyrene surface. In order to promote osteoinduction of hydroxyapatite (HA) scaffolds, bioinspired polymer-controlled mineralization was conducted

  14. Two dimensional simulation of high power laser-surface interaction

    International Nuclear Information System (INIS)

    Goldman, S.R.; Wilke, M.D.; Green, R.E.L.; Johnson, R.P.; Busch, G.E.

    1998-01-01

    For laser intensities in the range of 10 8 --10 9 W/cm 2 , and pulse lengths of order 10 microsec or longer, the authors have modified the inertial confinement fusion code Lasnex to simulate gaseous and some dense material aspects of the laser-matter interaction. The unique aspect of their treatment consists of an ablation model which defines a dense material-vapor interface and then calculates the mass flow across this interface. The model treats the dense material as a rigid two-dimensional mass and heat reservoir suppressing all hydrodynamic motion in the dense material. The computer simulations and additional post-processors provide predictions for measurements including impulse given to the target, pressures at the target interface, electron temperatures and densities in the vapor-plasma plume region, and emission of radiation from the target. The authors will present an analysis of some relatively well diagnosed experiments which have been useful in developing their modeling. The simulations match experimentally obtained target impulses, pressures at the target surface inside the laser spot, and radiation emission from the target to within about 20%. Hence their simulational technique appears to form a useful basis for further investigation of laser-surface interaction in this intensity, pulse-width range. This work is useful in many technical areas such as materials processing

  15. Constraining the surface properties of effective Skyrme interactions

    Science.gov (United States)

    Jodon, R.; Bender, M.; Bennaceur, K.; Meyer, J.

    2016-08-01

    Background: Deformation energy surfaces map how the total binding energy of a nuclear system depends on the geometrical properties of intrinsic configurations, thereby providing a powerful tool to interpret nuclear spectroscopy and large-amplitude collective-motion phenomena such as fission. The global behavior of the deformation energy is known to be directly connected to the surface properties of the effective interaction used for its calculation. Purpose: The precise control of surface properties during the parameter adjustment of an effective interaction is key to obtain a reliable and predictive description of nuclear properties. The most relevant indicator is the surface-energy coefficient asurf. There are several possibilities for its definition and estimation, which are not fully equivalent and require a computational effort that can differ by orders of magnitude. The purpose of this study is threefold: first, to identify a scheme for the determination of asurf that offers the best compromise between robustness, precision, and numerical efficiency; second, to analyze the correlation between values for asurf and the characteristic energies of the fission barrier of 240Pu; and third, to lay out an efficient and robust procedure for how the deformation properties of the Skyrme energy density functional (EDF) can be constrained during the parameter fit. Methods: There are several frequently used possibilities to define and calculate the surface energy coefficient asurf of effective interactions built for the purpose of self-consistent mean-field calculations. The most direct access is provided by the model system of semi-infinite nuclear matter, but asurf can also be extracted from the systematics of binding energies of finite nuclei. Calculations can be carried out either self-consistently [Hartree-Fock (HF)], which incorporates quantal shell effects, or in one of the semiclassical extended Thomas-Fermi (ETF) or modified Thomas-Fermi (MTF) approximations. The

  16. Surface water and groundwater interaction in Marala - Khanki area, Punjab

    International Nuclear Information System (INIS)

    Akram, W.; Ahmad, M.; Latif, Z.; Tariq, J.A.; Malik, M.R.

    2011-07-01

    Isotope hydrological investigations were carried out in two selected areas of Indus Basin viz. Haripur Area and Chashma- Taunsa Area for elucidating various aspects of surface water and groundwater interaction. Groundwater samples were collected on seasonal basis (low and high river discharge periods) while surface water samples were collected more frequently (weekly or monthly basis). Isotopic data suggested that there is no contribution of surface water to groundwater recharge in Haripur Area and rain is the prevailing source of groundwater recharge. The data further revealed that isotopic values of the Haripur pocket of Tarbela Lake are higher than those of Main Lake / Indus River meaning that there is a significant contribution of base flow in this pocket. Indus River appeared to be the dominant source of groundwater recharge at most of the locations in Chashma- Taunsa Area. Isotopic data of Indus River showed an increase at Taunsa as compared to Chashma in low flow period indicating the high contribution of base flow at this point in time. Stable isotopes were successfully used to quantify the base flow contribution. (author)

  17. Dynamics of gas-surface interactions atomic-level understanding of scattering processes at surfaces

    CERN Document Server

    Díez Muniño, Ricardo

    2013-01-01

    This book gives a representative survey of the state of the art of research on gas-surface interactions. It provides an overview of the current understanding of gas surface dynamics and, in particular, of the reactive and non-reactive processes of atoms and small molecules at surfaces. Leading scientists in the field, both from the theoretical and the experimental sides, write in this book about their most recent advances. Surface science grew as an interdisciplinary research area over the last decades, mostly because of new experimental technologies (ultra-high vacuum, for instance), as well as because of a novel paradigm, the ‘surface science’ approach. The book describes the second transformation which is now taking place pushed by the availability of powerful quantum-mechanical theoretical methods implemented numerically. In the book, experiment and theory progress hand in hand with an unprecedented degree of accuracy and control. The book presents how modern surface science targets the atomic-level u...

  18. An interaction network perspective on the relation between patterns of sea surface temperature variability and global mean surface temperature

    NARCIS (Netherlands)

    Tantet, A.J.J.; Dijkstra, H.A.

    2014-01-01

    On interannual- to multidecadal timescales variability in sea surface temperature appears to be organized in large-scale spatiotemporal patterns. In this paper, we investigate these patterns by studying the community structure of interaction networks constructed from sea surface temperature

  19. Cross-Surface: Workshop on Interacting with Multi-Device Ecologies in the Wild

    DEFF Research Database (Denmark)

    Houben, Steven; Vermeulen, Jo; Klokmose, Clemens Nylandsted

    2015-01-01

    In this workshop, we will review and discuss opportunities, technical challenges and problems with cross-device interactions in interactive multi-surface and multi-device ecologies. We aim to bring together researchers and practitioners currently working on novel techniques for cross......-surface interactions, identify application domains and enabling technologies for cross-surface interactions in the wild, and establish a research community to develop effective strategies for successful design of cross-device interactions....

  20. Multi-scale cell/surface interaction on modified titanium aluminum vanadium surfaces

    Science.gov (United States)

    Chen, Jianbo

    This dissertation presents a series of experimental studies of the effects of multi-scale cell/surface interactions on modified Ti-6Al-4V surfaces. These include laser-grooved surfaces; porous structures and RGD-coated laser-grooved surfaces. A nano-second DPSS UV lasers with a Gaussian pulse energy profile was used to introduce the desired micro-groove geometries onto Ti-6Al-4V surfaces. This was done without inducing micro-cracks or significant changes in surface chemistry within the heat affected zones. The desired 8-12 mum groove depths and widths were achieved by the control of pulse frequency, scan speed, and the lens focal length that controls spot size. The interactions between human osteosarcoma (HOS) cells and laser-grooved Ti-6Al-4V surfaces were investigated after 48 hours of cell culture. The cell behavior, including cell spreading, alignment and adhesion, was elucidated using scanning electronic microscopy (SEM), immuno-fluorescence staining and enzymatic detachment. Contact guidance was shown to increase as grooved spacing decreased. For the range of micro-groove geometries studied, micro-grooves with groove spacings of 20 mum provided the best combination of cell orientation and adhesion. Short-term adhesion experiments (15 mins to 1 day) also revealed that there is a positive correlation between cell orientation and cell adhesion. Contact guidance on the micro-grooved surfaces is shown to be enhanced by nano- and micro-scale asperities that provide sites for the attachment of lamellopodia during cell locomotion and spreading. Contact guidance is also promoted by the geometrical confinement provided by laser grooves. An experimental study of initial cell spreading and ingrowth into Ti-6Al-4V porous structures was also carried out on porous structures with different pore sizes and geometries. A combination of SEM, the tetrazolium salt (MTT) colorimetric assay and enzymatic detachment were used to study cell spreading and adhesion. The extent of cell

  1. SELMA: a mission to study lunar environment and surface interaction

    Science.gov (United States)

    Barabash, Stas; Futaana, Yoshifumi

    2017-04-01

    SELMA (Surface, Environment, and Lunar Magnetic Anomalies) proposed for the ESA M5 mission opportunity is a mission to study how the Moon environment and surface interact. SELMA addresses four overarching science questions: (1) What is the origin of water on the Moon? (2) How do the "volatile cycles" on the Moon work? (3) How do the lunar mini-magnetospheres work? (4) What is the influence of dust on the lunar environment and surface? SELMA uses a unique combination of remote sensing via UV, IR, and energetic neutral atoms and local measurements of plasma, fields, waves, exospheric gasses, and dust. It will also conduct an impact experiment to investigate volatile content in the soil of the permanently shadowed area of the Shakleton crater. SELMA carries an impact probe to sound the Reiner-Gamma mini-magnetosphere and its interaction with the lunar regolith from the SELMA orbit down to the surface. The SELMA science objectives include: - Establish the role of the solar wind and exosphere in the formation of the water bearing materials; - Determine the water content in the regolith of the permanently shadowed region and its isotope composition; - Establish variability, sources and sinks of the lunar exosphere and its relations to impact events; - Investigate a mini-magnetosphere interaction with the solar wind; - Investigate the long-term effects of mini-magnetospheres on the local surface; - Investigate how the impact events affect the lunar dust environments; - Investigate how the plasma effects result in lofting the lunar dust; SELMA is a flexible and short (15 months) mission including the following elements SELMA orbiter, SELMA Impact Probe for Magnetic Anomalies (SIP-MA), passive Impactor, and Relaying CubeSat (RCS). SELMA is placed on quasi-frozen polar orbit 30 km x 200 km with the pericenter over the South Pole. Approximately 9 months after the launch SELMA releases SIP-MA to sound the Reiner-Gamma magnetic anomaly with very high time resolution 10 sec

  2. Optodynamics: dynamic aspects of laser beam-surface interaction

    International Nuclear Information System (INIS)

    Možina, J; Diaci, J

    2012-01-01

    This paper presents a synthesis of the results of our original research in the area of laser-material interaction and pulsed laser material processing with a special emphasis on the dynamic aspects of laser beam-surface interaction, which include the links between the laser material removal and the resulting material motion. In view of laser material processing, a laser beam is not only considered as a tool but also as a generator of information about the material transformation. The information is retained and conveyed by different kinds of optically induced mechanical waves. Several generation/detection schemes have been developed to extract this information, especially in the field of non-destructive material evaluation. Blast and acoustic waves, which propagate in the air surrounding the work-piece, have been studied using microphone detection as well as various setups of the laser beam deflection probe. Stress waves propagating through the work-piece have been studied using piezoelectric transducers and laser interferometers.

  3. Lateral interactions and non-equilibrium in surface kinetics

    Science.gov (United States)

    Menzel, Dietrich

    2016-08-01

    Work modelling reactions between surface species frequently use Langmuir kinetics, assuming that the layer is in internal equilibrium, and that the chemical potential of adsorbates corresponds to that of an ideal gas. Coverage dependences of reacting species and of site blocking are usually treated with simple power law coverage dependences (linear in the simplest case), neglecting that lateral interactions are strong in adsorbate and co-adsorbate layers which may influence kinetics considerably. My research group has in the past investigated many co-adsorbate systems and simple reactions in them. We have collected a number of examples where strong deviations from simple coverage dependences exist, in blocking, promoting, and selecting reactions. Interactions can range from those between next neighbors to larger distances, and can be quite complex. In addition, internal equilibrium in the layer as well as equilibrium distributions over product degrees of freedom can be violated. The latter effect leads to non-equipartition of energy over molecular degrees of freedom (for products) or non-equal response to those of reactants. While such behavior can usually be described by dynamic or kinetic models, the deeper reasons require detailed theoretical analysis. Here, a selection of such cases is reviewed to exemplify these points.

  4. Interaction of the Helium, Hydrogen, Air, Argon, and Nitrogen Bubbles with Graphite Surface in Water.

    Science.gov (United States)

    Bartali, Ruben; Otyepka, Michal; Pykal, Martin; Lazar, Petr; Micheli, Victor; Gottardi, Gloria; Laidani, Nadhira

    2017-05-24

    The interaction of the confined gas with solid surface immersed in water is a common theme of many important fields such as self-cleaning surface, gas storage, and sensing. For that reason, we investigated the gas-graphite interaction in the water medium. The graphite surface was prepared by mechanical exfoliation of highly oriented pyrolytic graphite (HOPG). The surface chemistry and morphology were studied by X-ray photoelectron spectroscopy, profilometry, and atomic force microscopy. The surface energy of HOPG was estimated by contact angle measurements using the Owens-Wendt method. The interaction of gases (Ar, He, H 2 , N 2 , and air) with graphite was studied by a captive bubble method, in which the gas bubble was in contact with the exfoliated graphite surface in water media. The experimental data were corroborated by molecular dynamics simulations and density functional theory calculations. The surface energy of HOPG equaled to 52.8 mJ/m 2 and more of 95% of the surface energy was attributed to dispersion interactions. The results on gas-surface interaction indicated that HOPG surface had gasphilic behavior for helium and hydrogen, while gasphobic behavior for argon and nitrogen. The results showed that the variation of the gas contact angle was related to the balance between the gas-surface and gas-gas interaction potentials. For helium and hydrogen the gas-surface interaction was particularly high compared to gas-gas interaction and this promoted the favorable interaction with graphite surface.

  5. Interaction between Palladium Nanoparticles and Surface-Modified Carbon Nanotubes: Role of Surface Functionalities

    DEFF Research Database (Denmark)

    Zhang, Bingsen; Shao, Lidong; Zhang, Wei

    2014-01-01

    degrees C. We focus on probing the effects of oxygen and nitrogen-containing functional groups on supported palladium nanoparticles (NPs) in the model catalytic system. The stability of palladium NPs supported on CNTs depends strongly on the surface properties of CNTs. Moreover, the oxygen...... feature, instability, and subtle response of the components upon application of an external field. Herein, we use insitu TEM, electron energy loss spectroscopy, and X-ray photoelectron spectroscopy techniques to record the interaction in palladium on carbon nanotubes (CNTs) from room temperature to 600...

  6. Interaction of positron beams with thin silver foils and surfaces

    International Nuclear Information System (INIS)

    Rysholt Poulsen, M.

    1994-01-01

    Experimental investigations of positron interactions with solid silver and the necessary platform to analyse the data have been presented. The main objective was to study Ps formation at a Ag(100) surface. The different ingredients of the scenario, including thermalization and diffusion of positrons and emission of Ps, were analysed and quantified in whatever way appropriate. The scattering and possible thermalization were described. The parametrization of Monte-Carlo simulated implantation profiles for semi-infinite materials were presented and the applicability of such profiles to thin foils assessed. The latter was done in conjunction with an analysis of experimental data on thermalization and diffusion in 1900 Aa Ag(100) foils. The necessity for MC simulated rather than parametrized implantation profiles was argued. The velocity of thermally desorbed Ps from a Ag(100) surface at ∼800 K appeared to obey and one-dimensional Maxwell Boltzmann distribution multiplied by a velocity dependent factor. More experimental investigations are needed before firm conclusions can be made on the nature of the emission process. The velocity distribution, though, was found to be near-thermal and indicative of the sample temperature. It has been shown that positrons can be converted into Ps atoms in the transmission geometry of a thin 1900 Aa Ag(100) foil with a high efficiency. Furthermore, 61% of the emitted Ps will have a mean velocity of v z =1.2x10 5 m/sec and 39% will have a maximum kinetic energy of 1.5 eV (v z =5.1x10 5 m/sec) at a foil temperature of 800 K, all velocities that are suitable for producing a 'dense' Ps gas target. (EG) 12 refs

  7. Water on hydrophobic surfaces: Mechanistic modeling of hydrophobic interaction chromatography.

    Science.gov (United States)

    Wang, Gang; Hahn, Tobias; Hubbuch, Jürgen

    2016-09-23

    Mechanistic models are successfully used for protein purification process development as shown for ion-exchange column chromatography (IEX). Modeling and simulation of hydrophobic interaction chromatography (HIC) in the column mode has been seldom reported. As a combination of these two techniques is often encountered in biopharmaceutical purification steps, accurate modeling of protein adsorption in HIC is a core issue for applying holistic model-based process development, especially in the light of the Quality by Design (QbD) approach. In this work, a new mechanistic isotherm model for HIC is derived by consideration of an equilibrium between well-ordered water molecules and bulk-like ordered water molecules on the hydrophobic surfaces of protein and ligand. The model's capability of describing column chromatography experiments is demonstrated with glucose oxidase, bovine serum albumin (BSA), and lysozyme on Capto™ Phenyl (high sub) as model system. After model calibration from chromatograms of bind-and-elute experiments, results were validated with batch isotherms and prediction of further gradient elution chromatograms. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Interaction of lectins with membrane receptors on erythrocyte surfaces.

    Science.gov (United States)

    Sung, L A; Kabat, E A; Chien, S

    1985-08-01

    The interactions of human genotype AO erythrocytes (red blood cells) (RBCs) with N-acetylgalactosamine-reactive lectins isolated from Helix pomatia (HPA) and from Dolichos biflorus (DBA) were studied. Binding curves obtained with the use of tritium-labeled lectins showed that the maximal numbers of lectin molecules capable of binding to human genotype AO RBCs were 3.8 X 10(5) and 2.7 X 10(5) molecules/RBC for HPA and DBA, respectively. The binding of one type of lectin may influence the binding of another type. HPA was found to inhibit the binding of DBA, but not vice versa. The binding of HPA was weakly inhibited by a beta-D-galactose-reactive lectin isolated from Ricinus communis (designated RCA1). Limulus polyphemus lectin (LPA), with specificity for N-acetylneuraminic acid, did not influence the binding of HPA but enhanced the binding of DBA. About 80% of LPA receptors (N-acetylneuraminic acid) were removed from RBC surfaces by neuraminidase treatment. Neuraminidase treatment of RBCs resulted in increases of binding of both HPA and DBA, but through different mechanisms. An equal number (7.6 X 10(5) of new HPA sites were generated on genotypes AO and OO RBCs by neuraminidase treatment, and these new sites accounted for the enhancement (AO cells) and appearance (OO cells) of hemagglutinability by HPA. Neuraminidase treatment did not generate new DBA sites, but increased the DBA affinity for the existing receptors; as a result, genotype AO cells increased their hemagglutinability by DBA, while OO cells remained unagglutinable. The use of RBCs of different genotypes in binding assays with 3H-labeled lectins of known specificities provides an experimental system for studying cell-cell recognition and association.

  9. Superparamagnetic bead interactions with functionalized surfaces characterized by an immunomicroarray

    DEFF Research Database (Denmark)

    Skottrup, Peter Durand; Hansen, Mikkel Fougt; Moresco, Jacob Lange

    2010-01-01

    an immunomicroarray for systematic studies of the binding properties of 10 different micro-/nano-sized streptavidin-functionalized beads to a biotin substrate immobilized on SiO2 with or without surface modification SiO2 surface cleaning, immobilized substrate concentration and surface blocking conditions were...

  10. Asperity Interaction and Substrate Deformation in Statistical Summation Models of Contact Between Rough Surfaces

    NARCIS (Netherlands)

    Vakis, Antonis I.

    A method is proposed to account for asperity interaction and bulk substrate deformation in models that utilize statistical summation of asperity forces to characterize contact between rough surfaces. Interaction deformations of noncontacting asperities are calculated based on the probability that

  11. Groundwater–surface water interactions in wetlands for integrated water resources management (preface)

    NARCIS (Netherlands)

    Schot, P.P.; Winter, T.C.

    2006-01-01

    Groundwater–surface water interactions constitute an important link between wetlands and the surrounding catchment. Wetlands may develop in topographic lows where groundwater exfiltrates. This water has its functions for ecological processes within the wetland, while surface water outflow from

  12. The surface chemistry of metal-oxygen interactions

    DEFF Research Database (Denmark)

    Stokbro, Kurt; Baroni, Stefano

    1997-01-01

    We report on a computational study of the clean and oxygen-covered Rh(110) surface, based on density-functional theory within the local-density approximation. We have used plane-wave basis sets and Vanderbilt ultra-soft pseudopotentials. For the clean surface, we present results for the equilibrium...... structure, surface energy and surface stress of the unreconstructed and (1 x 2) reconstructed structures. For the oxygen-covered surface we have performed a geometry optimization at 0.5, 1, and 2 monolayer oxygen coverages, and we present results for the equilibrium configurations, workfunctions and oxygen...

  13. Hydrogen interactions with polycrystalline and with deposited titanium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Azoulay, A. [Ben-Gurion Univ. of the Negev, Beersheba (Israel); Shamir, N. [Nuclear Research Center-Negev, PO Box 9001, Beer Sheva (Israel); Fromm, E. [Max-Planck Institute fuer Metallforschung, Stuttgart (Germany); Szokefalvi-Nagy, A. [Max-Planck Institute fuer Metallforschung, Stuttgart (Germany); Mintz, M.H. [Ben-Gurion Univ. of the Negev, Beersheba (Israel)]|[Nuclear Research Center-Negev, PO Box 9001, Beer Sheva (Israel)

    1997-02-15

    The room temperature kinetics of hydrogen chemisorption and adsorption on polycrystalline and on deposited (sputter-deposited and evaporation-deposited) titanium surfaces were studied. Measurements of hydrogen surface accumulation were performed in a combined surface analyses system incorporating direct recoils spectrometry and Auger electron spectroscopy (AES). There, three different types of surface cleaning procedure were applied: heat-flashing, sputtering and sputter-deposition of titanium on a polycrystalline titanium substrate. The surface chemisorption kinetics obtained for the deposited samples were compared with the total kinetics of the gas phase consumption, performed in a volumetric Wagener system. From this comparison it was possible to distinguish between topmost surface chemisorption and subsurface (or bulk) absorption kinetics. It was concluded that, for all types of surface studied, hydrogen chemisorbed according to a Langmuir-type random two-sites chemisorption model, with high (close to unity) zero-coverage sticking probabilities. The only difference between these surfaces was in their roughness factors, which increased going from the heat-flashed, through the sputtered, to the deposited surfaces. Following the initial stage of a chemisorbed surface layer formation, constant-rate absorption of hydrogen proceeded over a very wide range of exposures (greater than 10{sup 4} Langmuirs). The accommodation probability of hydrogen during this linear stage was about 10{sup -2}. It is possible that this absorption process is controlled by the chemisorption of the H{sub 2} on the surface hydride phase, formed by the earlier hydrogen chemisorption. (orig.)

  14. Argon ion beam interaction on polyethylene terephthalate surface by ...

    Indian Academy of Sciences (India)

    Polyethylene terephthalate (PET) has a wide variety of applications ranging from making regular bottles to biosensors. However, for many of these applications, surface treatment is needed to improve its surface characteristics such as adhesion to other materials. In this study, we focussed on treating PET foils by dense Ar ...

  15. Argon ion beam interaction on polyethylene terephthalate surface by ...

    Indian Academy of Sciences (India)

    Polyethylene terephthalate surface treatment; Amirkabir plasma focus; plasma focus ... and ion-assisted coating [5], ion implantation and thermal surface treatment [6]. ..... after one month for steps (a) and (b). Therefore, in many applications it is suggested that the adhesion takes place immediately after plasma exposure to ...

  16. Estimation of the solubility parameters of model plant surfaces and agrochemicals: a valuable tool for understanding plant surface interactions

    OpenAIRE

    Khayet, Mohamed; Fernandez Fernandez, Victoria

    2012-01-01

    Background Most aerial plant parts are covered with a hydrophobic lipid-rich cuticle, which is the interface between the plant organs and the surrounding environment. Plant surfaces may have a high degree of hydrophobicity because of the combined effects of surface chemistry and roughness. The physical and chemical complexity of the plant cuticle limits the development of models that explain its internal structure and interactions with surface-applied agrochemicals. In this article we int...

  17. Ion-surface interaction: simulation of plasma-wall interaction (ITER)

    International Nuclear Information System (INIS)

    Salou, Pierre

    2013-01-01

    The wall materials of magnetic confinement in fusion machines are exposed to an aggressive environment; the reactor blanket is bombarded with a high flux of particles extracted from the plasma, leading to the sputtering of surface material. This sputtering causes wall erosion as well as plasma contamination problems. In order to control fusion reactions in complex reactors, it is thus imperative to well understand the plasma-wall interactions. This work proposes the study of the sputtering of fusion relevant materials. We propose to simulate the charged particles influx by few keV single-charged ion beams. This study is based on the catcher method; to avoid any problem of pollution (especially in the case of carbon) we designed a new setup allowing an in situ Auger electron spectroscopy analysis. The results provide the evolution of the angular distribution of the sputtering yield as a function of the ion mass (from helium to xenon) and its energy (from 3 keV to 9 keV). (author) [fr

  18. Surface-induced charge at the Ge (001) surface and its interaction with self-interstitials

    Energy Technology Data Exchange (ETDEWEB)

    Kamiyama, Eiji; Sueoka, Koji [Department of Communication Engineering, Okayama Prefectural University, 111 Kuboki, Soja-shi, Okayama-ken 719-1197 (Japan); Vanhellemont, Jan [Department of Solid State Sciences, Ghent University, B-9000 Gent (Belgium)

    2014-02-21

    The Ge (001) surface with dimer structure, is negatively charged while into the bulk, positive charges are observed even deeper than the fifteenth layer from the surface. This is different from the Si case. This charge distribution can lead to the repulsion of positively charged self-interstitials by the positively charged near surface layer in an implantation or irradiation process. Self-interstitial reflection by Ge surfaces had been proposed to explain the results of diffusion experiments during irradiation whereby positively charged self-interstitials are generated by collisions of highly energetic particles with Ge atoms. We investigated different Ge (001) surface comparing an as-cleaved surface with dangling bonds to a surface with dimer structure, and to a surface terminated by hydrogen atoms. The effect of these different surface terminations on the surface-induced charges in the near surface bulk were calculated by ab initio techniques.

  19. Spectral asymptotics of a strong δ′ interaction supported by a surface

    International Nuclear Information System (INIS)

    Exner, Pavel; Jex, Michal

    2014-01-01

    Highlights: • Attractive δ ′ interactions supported by a smooth surface are considered. • Surfaces can be either infinite and asymptotically planar, or compact and closed. • Spectral asymptotics is determined by the geometry of the interaction support. - Abstract: We derive asymptotic expansion for the spectrum of Hamiltonians with a strong attractive δ ′ interaction supported by a smooth surface in R 3 , either infinite and asymptotically planar, or compact and closed. Its second term is found to be determined by a Schrödinger type operator with an effective potential expressed in terms of the interaction support curvatures

  20. Interaction of ethanol and water with the {1014} surface of calcite

    DEFF Research Database (Denmark)

    Cooke, David; Gray, R J; Sand, K K

    2010-01-01

    Molecular dynamics simulations have been used to model the interaction between ethanol, water, and the {1014} surface of calcite. Our results demonstrate that a single ethanol molecule is able to form two interactions with the mineral surface (both Ca-O and O-H), resulting in a highly ordered...... the starting configuration consists of a complete monolayer of water at the surface. The computational results are in good agreement with the results from atomic force microscopy experiments where it is observed that a layer of ethanol remains attached to the calcite surface, decreasing its ability to interact...

  1. Surface/Fluid Interactions in Micro and Nano-Channels

    National Research Council Canada - National Science Library

    Meinhart, Carl D

    2007-01-01

    ...-channels can create slip flow whereby the no-slip boundary condition may not be valid. The slip flow may be a result of a low-viscosity nanoscale gaseous layer forming between the fluid and the microchannel surface...

  2. Controlling coverage of solution cast materials with unfavourable surface interactions

    KAUST Repository

    Burlakov, V. M.

    2014-03-03

    Creating uniform coatings of a solution-cast material is of central importance to a broad range of applications. Here, a robust and generic theoretical framework for calculating surface coverage by a solid film of material de-wetting a substrate is presented. Using experimental data from semiconductor thin films as an example, we calculate surface coverage for a wide range of annealing temperatures and film thicknesses. The model generally predicts that for each value of the annealing temperature there is a range of film thicknesses leading to poor surface coverage. The model accurately reproduces solution-cast thin film coverage for organometal halide perovskites, key modern photovoltaic materials, and identifies processing windows for both high and low levels of surface coverage. © 2014 AIP Publishing LLC.

  3. Hyperthermal Carbon Dioxide Interactions with Self-Assembled Monolayer Surfaces

    Science.gov (United States)

    2013-09-08

    They measured two populations of rotational distributions, one corresponding to the surface temperature and the other corresponding to a much higher...involved in the collision. This is the first application of the soft-sphere model to the scattering of molecules, which have internal structure, as...temperature. Scattering dynamics on these fluorinated liquid and SAM surfaces were compared directly. It was found that the scattering dynamics were very

  4. Measurement of the interaction between the flow and the free surface of a liquid

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Koji [Univ. of Tokyo, Ibaraki (Japan); Schmidl, W.D.; Philip, O.G. [Texas A& M Univ., College Station, TX (United States)

    1995-09-01

    The interaction between the flow and free surface was evaluated measuring the velocity distribution and surface movement simultaneously. The test section was a rectangular tank having a free surface. A rectangular nozzle was set near the free surface, causing the wavy free surface condition. The flow under the free surface was visualized by a laser light sheet and small tracer particles. With image processing techniques, the movement of the free surface and the movement of the particles were simultaneously measured from the recorded images, resulting in the velocity distributions and surface locations. Then, the interactions between the flow and free surface were evaluated using the form of turbulent energy and surface-related turbulent values. By increasing the turbulent energy near the free surface, the fluctuations of the free surface height and the inclination of the free surface were increased. The higher fluctuation of horizontal velocity was related to the higher surface position and negative inclination. The image processing technique is found to be very useful to evaluate the interaction between free surface and flow.

  5. Dynamics of intramolecular spin exchange interaction of a nitronyl nitroxide diradical in solution and on surfaces

    OpenAIRE

    Lloveras Montserrat, Vega; Badetti, Elena; Veciana Miró, Jaume; Vidal-Gancedo, José

    2016-01-01

    In this paper we report the study of the dynamics of a thermally modulated intramolecular spin exchange interaction of a novel diradical nitronyl nitroxide-substituted disulfide in solution and when it is grafted on a gold surface. The structure of this diradical was designed to have flexible chains leading to intramolecular collisions and hence spin exchange interaction, and with an appropriate binding group to be grafted on the gold surface to study its behavior on the surface. In solution,...

  6. Surface interactions of cesium and boric acid with stainless steel

    International Nuclear Information System (INIS)

    Grossman-Canfield, N.

    1995-08-01

    In this report, the effects of cesium hydroxide and boric acid on oxidized stainless steel surfaces at high temperatures and near one atmosphere of pressure are investigated. This is the first experimental investigation of this chemical system. The experimental investigations were performed using a mass spectrometer and a mass electrobalance. Surfaces from the different experiments were examined using a scanning electron microscope to identify the presence of deposited species, and electron spectroscopy for chemical analysis to identify the species deposited on the surface. A better understanding of the equilibrium thermodynamics, the kinetics of the steam-accelerated volatilizations, and the release kinetics are gained by these experiments. The release rate is characterized by bulk vaporization/gas-phase mass transfer data. The analysis couples vaporization, deposition, and desorption of the compounds formed by cesium hydroxide and boric acid under conditions similar to what is expected during certain nuclear reactor accidents. This study shows that cesium deposits on an oxidized stainless steel surface at temperatures between 1000 and 1200 Kelvin. Cesium also deposits on stainless steel surfaces coated with boric oxide in the same temperature ranges. The mechanism for cesium deposition onto the oxide layer was found to involve the chemical reaction between cesium and chromate. Some revaporization in the cesium hydroxide-boric acid system was observed. It has been found that under the conditions given, boric acid will react with cesium hydroxide to form cesium metaborate. A model is proposed for this chemical reaction

  7. The dynamics of molecular interactions and chemical reactions at metal surfaces: testing the foundations of theory.

    Science.gov (United States)

    Golibrzuch, Kai; Bartels, Nils; Auerbach, Daniel J; Wodtke, Alec M

    2015-04-01

    We review studies of molecular interactions and chemical reactions at metal surfaces, emphasizing progress toward a predictive theory of surface chemistry and catalysis. For chemistry at metal surfaces, a small number of central approximations are typically made: (a) the Born-Oppenheimer approximation of electronic adiabaticity, (b) the use of density functional theory at the generalized gradient approximation level, (c) the classical approximation for nuclear motion, and (d) various reduced-dimensionality approximations. Together, these approximations constitute a provisional model for surface chemical reactivity. We review work on some carefully studied examples of molecules interacting at metal surfaces that probe the validity of various aspects of the provisional model.

  8. Integrated modeling of groundwater–surface water interactions in a tile-drained agricultural field

    NARCIS (Netherlands)

    Rosemeijer, J.C.; Velde, van der Y.; McLaren, R.G.; Geer, van F.C.; Broers, H.P.; Bierkens, M.F.P.

    2010-01-01

    Understanding the dynamics of groundwater–surface water interaction is needed to evaluate and simulate water and solute transport in catchments. However, direct measurements of the contributions of different flow routes from specific surfaces within a catchment toward the surface water are rarely

  9. Predicting Nanocrystal Shape through Consideration of Surface-Ligand Interactions

    KAUST Repository

    Bealing, Clive R.

    2012-03-27

    Density functional calculations for the binding energy of oleic acid-based ligands on Pb-rich {100} and {111} facets of PbSe nanocrystals determine the surface energies as a function of ligand coverage. Oleic acid is expected to bind to the nanocrystal surface in the form of lead oleate. The Wulff construction predicts the thermodynamic equilibrium shape of the PbSe nanocrystals. The equilibrium shape is a function of the ligand surface coverage, which can be controlled by changing the concentration of oleic acid during synthesis. The different binding energy of the ligand on the {100} and {111} facets results in different equilibrium ligand coverages on the facets, and a transition in the equilibrium shape from octahedral to cubic is predicted when increasing the ligand concentration during synthesis. © 2012 American Chemical Society.

  10. Resonance Fluorescence of Many Interacting Adatoms at a Metal Surface.

    Science.gov (United States)

    1983-06-01

    of the system, one can write a total Hamiltonian as HA + B + AB + HAA HABA + HAR HBB + HAF (7) HA and H are the unperturbed Hamiltonians for the...adatom-plasmon interaction may be further broadened via HAA and HABA in which the collisional effects may be significant for a high-coverage system and/or

  11. Streamer-Surface Interaction in Heptane with Micro-Gaps

    International Nuclear Information System (INIS)

    Hamdan, A.; Noel, C.; Henrion, G.; Belmonte, Th.

    2011-01-01

    Interaction between streamer and 316L Stainless Steel substrate in heptane with micro-gaps gives craters with a very specific shape. The role of the Marangoni forces is stressed, a phenomenon which is generally neglected in EDM processes to describe the shape of the craters.

  12. Estimation of the solubility parameters of model plant surfaces and agrochemicals: a valuable tool for understanding plant surface interactions.

    Science.gov (United States)

    Khayet, Mohamed; Fernández, Victoria

    2012-11-14

    Most aerial plant parts are covered with a hydrophobic lipid-rich cuticle, which is the interface between the plant organs and the surrounding environment. Plant surfaces may have a high degree of hydrophobicity because of the combined effects of surface chemistry and roughness. The physical and chemical complexity of the plant cuticle limits the development of models that explain its internal structure and interactions with surface-applied agrochemicals. In this article we introduce a thermodynamic method for estimating the solubilities of model plant surface constituents and relating them to the effects of agrochemicals. Following the van Krevelen and Hoftyzer method, we calculated the solubility parameters of three model plant species and eight compounds that differ in hydrophobicity and polarity. In addition, intact tissues were examined by scanning electron microscopy and the surface free energy, polarity, solubility parameter and work of adhesion of each were calculated from contact angle measurements of three liquids with different polarities. By comparing the affinities between plant surface constituents and agrochemicals derived from (a) theoretical calculations and (b) contact angle measurements we were able to distinguish the physical effect of surface roughness from the effect of the chemical nature of the epicuticular waxes. A solubility parameter model for plant surfaces is proposed on the basis of an increasing gradient from the cuticular surface towards the underlying cell wall. The procedure enabled us to predict the interactions among agrochemicals, plant surfaces, and cuticular and cell wall components, and promises to be a useful tool for improving our understanding of biological surface interactions.

  13. Estimation of the solubility parameters of model plant surfaces and agrochemicals: a valuable tool for understanding plant surface interactions

    Science.gov (United States)

    2012-01-01

    Background Most aerial plant parts are covered with a hydrophobic lipid-rich cuticle, which is the interface between the plant organs and the surrounding environment. Plant surfaces may have a high degree of hydrophobicity because of the combined effects of surface chemistry and roughness. The physical and chemical complexity of the plant cuticle limits the development of models that explain its internal structure and interactions with surface-applied agrochemicals. In this article we introduce a thermodynamic method for estimating the solubilities of model plant surface constituents and relating them to the effects of agrochemicals. Results Following the van Krevelen and Hoftyzer method, we calculated the solubility parameters of three model plant species and eight compounds that differ in hydrophobicity and polarity. In addition, intact tissues were examined by scanning electron microscopy and the surface free energy, polarity, solubility parameter and work of adhesion of each were calculated from contact angle measurements of three liquids with different polarities. By comparing the affinities between plant surface constituents and agrochemicals derived from (a) theoretical calculations and (b) contact angle measurements we were able to distinguish the physical effect of surface roughness from the effect of the chemical nature of the epicuticular waxes. A solubility parameter model for plant surfaces is proposed on the basis of an increasing gradient from the cuticular surface towards the underlying cell wall. Conclusions The procedure enabled us to predict the interactions among agrochemicals, plant surfaces, and cuticular and cell wall components, and promises to be a useful tool for improving our understanding of biological surface interactions. PMID:23151272

  14. Interaction of surface-modified silica nanoparticles with clay minerals

    Directory of Open Access Journals (Sweden)

    Cigdem Omurlu

    2016-05-01

    Full Text Available Abstract In this study, the adsorption of 5-nm silica nanoparticles onto montmorillonite and illite is investigated. The effect of surface functionalization was evaluated for four different surfaces: unmodified, surface-modified with anionic (sulfonate, cationic (quaternary ammonium (quat, and nonionic (polyethylene glycol (PEG surfactant. We employed ultraviolet–visible spectroscopy to determine the concentration of adsorbed nanoparticles in conditions that are likely to be found in subsurface reservoir environments. PEG-coated and quat/PEG-coated silica nanoparticles were found to significantly adsorb onto the clay surfaces, and the effects of electrolyte type (NaCl, KCl and concentration, nanoparticle concentration, pH, temperature, and clay type on PEG-coated nanoparticle adsorption were studied. The type and concentration of electrolytes were found to influence the degree of adsorption, suggesting a relationship between the interlayer spacing of the clay and the adsorption ability of the nanoparticles. Under the experimental conditions reported in this paper, the isotherms for nanoparticle adsorption onto montmorillonite at 25 °C indicate that adsorption occurs less readily as the nanoparticle concentration increases.

  15. Importance of physical vs. chemical interactions in surface shear rheology

    NARCIS (Netherlands)

    Wierenga, P.A.; Kosters, H.; Egmond, M.R.; Voragen, A.G.J.; Jongh, H.H.J. de

    2006-01-01

    The stability of adsorbed protein layers against deformation has in literature been attributed to the formation of a continuous gel-like network. This hypothesis is mostly based on measurements of the increase of the surface shear elasticity with time. For several proteins this increase has been

  16. Vortex-Surface Interactions: Vortex Dynamics and Instabilities

    Science.gov (United States)

    2015-10-16

    Crow instability (see for example Leweke & Williamson, 2012). (b) Short-wave cooperative elliptic instability (Leweke & Williamson 1998). (c...vortex generators. Of interest in such studies would be the formation of secondary vorticity from the surface, the downstream vortex trajectories , and

  17. The interaction between surface water and groundwater and its ...

    Indian Academy of Sciences (India)

    The relationship between surface water and groundwater not only influences the water quantity, but also affects the water quality. The stable isotopes (δD, δ18O) and hydrochemical compositions in water samples were analysed in the Second Songhua River basin. The deep groundwater is mainly recharged from shallow ...

  18. ISOPOOH interacting with plant surfaces - a new source of MVK?

    Science.gov (United States)

    Canaval, Eva; Partoll, Eva Maria; Mentler, Bernhard; Keutsch, Frank; Schnitzler, Jörg-Peter; Hansel, Armin

    2017-04-01

    Isoprene is the most dominant BVOC emitted into the atmosphere. In rural areas with low concentrations of NOx Isoprene can rapidly react with hydroxyl radicals forming several isoprene hydroxy hydroperoxide (ISOPOOH) isomeres. It is known that ISOPOOH undergoes catalytical conversion on metal surfaces forming MVK and MACR and other oxygenated species. Thus, standard PTR-MS instruments containing metal drift rings convert ISOPOOH to MVK and MACR and cannot measure ISOPOOH artifact free. In our studies we were interested in the surfaces catalyzed reactions of ISOPOOH on plant surfaces. For this aim we used poplar plants, which represent a major biomass producing species. For the experiments the poplars were placed in an enclosure setup with only PTFE, PFA and PEEK as ISOPOOH showed negligible decomposition on those materials. ISOPOOH was mixed quantitatively to the air stream with a Liquid Calibration Unit resulting in volume mixing ratios of 8-50 ppbv. A novel Switchable-Reagent-Ion-Time-of-Flight-MS (SRI-ToF-MS) instrument containing conductive peek drift rings was used to analyze the VOC composition switching between enclosure inlet and outlet in real-time. The use of H_3O+ and NH_4+ as reagent ions allows the fragmention free measurement of isoprene peroxides and C_5-diols. We investigated day/night (stomatal open-closed) changes and found under daytime conditions a strong uptake of ISOPOOH and a clear emission of MVK for low and high concentrations of ISOPOOH. Fumigation with 8-10 ppbv ISOPOOH under night conditions the poplar showed only a small uptake of ISOPOOH accompanied by no visible MVK emissions. But fumigation of poplar with 50 ppbv showed a clear uptake during night time conditions. This indicates that the plant surfaces also play an important role in producing MVK while undergoing surface assisted reactions with ISOPOOH. Moreover during long fumigation (6-8 h) with ISOPOOH the majority of investigated poplars showed increasing levels of stress

  19. Asperity interaction in elastic-plastic contact of rough surfaces in presence of adhesion

    International Nuclear Information System (INIS)

    Sahoo, Prasanta; Banerjee, Atanu

    2005-01-01

    This paper presents an analysis of the effect of asperity interaction in elastic-plastic contact of rough surfaces in the presence of adhesion. The micro-contact model of asperity interactions, developed by Zhao and Chang (2001 Trans. ASME: J. Tribol. 123 857-64), is integrated into the elastic-plastic contact model developed by Roy Chowdhury and Ghosh (1994 Wear 174 9-19) to allow the asperity interaction and elastic-plastic deformation in the presence of surface forces to be considered simultaneously. The well-established elastic and plastic adhesion indices are used to consider the different conditions that arise as a result of varying load and material parameters. Results show that asperity interaction influences the loading-unloading behaviour in elastic-plastic adhesive contact of rough surfaces and in general asperity interactions reduce the effect of surface forces

  20. Protein-Protein Interaction Site Predictions with Three-Dimensional Probability Distributions of Interacting Atoms on Protein Surfaces

    Science.gov (United States)

    Chen, Ching-Tai; Peng, Hung-Pin; Jian, Jhih-Wei; Tsai, Keng-Chang; Chang, Jeng-Yih; Yang, Ei-Wen; Chen, Jun-Bo; Ho, Shinn-Ying; Hsu, Wen-Lian; Yang, An-Suei

    2012-01-01

    Protein-protein interactions are key to many biological processes. Computational methodologies devised to predict protein-protein interaction (PPI) sites on protein surfaces are important tools in providing insights into the biological functions of proteins and in developing therapeutics targeting the protein-protein interaction sites. One of the general features of PPI sites is that the core regions from the two interacting protein surfaces are complementary to each other, similar to the interior of proteins in packing density and in the physicochemical nature of the amino acid composition. In this work, we simulated the physicochemical complementarities by constructing three-dimensional probability density maps of non-covalent interacting atoms on the protein surfaces. The interacting probabilities were derived from the interior of known structures. Machine learning algorithms were applied to learn the characteristic patterns of the probability density maps specific to the PPI sites. The trained predictors for PPI sites were cross-validated with the training cases (consisting of 432 proteins) and were tested on an independent dataset (consisting of 142 proteins). The residue-based Matthews correlation coefficient for the independent test set was 0.423; the accuracy, precision, sensitivity, specificity were 0.753, 0.519, 0.677, and 0.779 respectively. The benchmark results indicate that the optimized machine learning models are among the best predictors in identifying PPI sites on protein surfaces. In particular, the PPI site prediction accuracy increases with increasing size of the PPI site and with increasing hydrophobicity in amino acid composition of the PPI interface; the core interface regions are more likely to be recognized with high prediction confidence. The results indicate that the physicochemical complementarity patterns on protein surfaces are important determinants in PPIs, and a substantial portion of the PPI sites can be predicted correctly with

  1. Advanced Response Surface Modeling of Ares I Roll Control Jet Aerodynamic Interactions

    Science.gov (United States)

    Favaregh, Noah M.

    2010-01-01

    The Ares I rocket uses roll control jets. These jets have aerodynamic implications as they impinge on the surface and protuberances of the vehicle. The jet interaction on the body can cause an amplification or a reduction of the rolling moment produced by the jet itself, either increasing the jet effectiveness or creating an adverse effect. A design of experiments test was planned and carried out using computation fluid dynamics, and a subsequent response surface analysis ensued on the available data to characterize the jet interaction across the ascent portion of the Ares I flight envelope. Four response surface schemes were compared including a single response surface covering the entire design space, separate sector responses that did not overlap, continuously overlapping surfaces, and recursive weighted response surfaces. These surfaces were evaluated on traditional statistical metrics as well as visual inspection. Validation of the recursive weighted response surface was performed using additionally available data at off-design point locations.

  2. Boundary Slip and Surface Interaction: A Lattice Boltzmann Simulation

    International Nuclear Information System (INIS)

    Yan-Yan, Chen; Hua-Bing, Li; Hou-Hui, Yi

    2008-01-01

    The factors affecting slip length in Couette geometry flows are analysed by means of a two-phase mesoscopic lattice Boltzmann model including non-ideal fluid-fluid and fluid-wall interactions. The main factors influencing the boundary slip are the strength of interactions between fluid-fluid and fluid-wall particles. Other factors, such as fluid viscosity, bulk pressure may also change the slip length. We find that boundary slip only occurs under a certain density (bulk pressure). If the density is large enough, the slip length will tend to zero. In our simulations, a low density layer near the wall does not need to be postulated a priori but emerges naturally from the underlying non-ideal mesoscopic dynamics. It is the low density layer that induces the boundary slip. The results may be helpful to understand recent experimental observations on the slippage of micro flows

  3. In-cell thermodynamics and a new role for protein surfaces.

    Science.gov (United States)

    Smith, Austin E; Zhou, Larry Z; Gorensek, Annelise H; Senske, Michael; Pielak, Gary J

    2016-02-16

    There is abundant, physiologically relevant knowledge about protein cores; they are hydrophobic, exquisitely well packed, and nearly all hydrogen bonds are satisfied. An equivalent understanding of protein surfaces has remained elusive because proteins are almost exclusively studied in vitro in simple aqueous solutions. Here, we establish the essential physiological roles played by protein surfaces by measuring the equilibrium thermodynamics and kinetics of protein folding in the complex environment of living Escherichia coli cells, and under physiologically relevant in vitro conditions. Fluorine NMR data on the 7-kDa globular N-terminal SH3 domain of Drosophila signal transduction protein drk (SH3) show that charge-charge interactions are fundamental to protein stability and folding kinetics in cells. Our results contradict predictions from accepted theories of macromolecular crowding and show that cosolutes commonly used to mimic the cellular interior do not yield physiologically relevant information. As such, we provide the foundation for a complete picture of protein chemistry in cells.

  4. Surface nucleation and growth in the system of interacting particles

    Czech Academy of Sciences Publication Activity Database

    Chvoj, Zdeněk; Chromcová, Zdeňka

    2012-01-01

    Roč. 24, č. 13 (2012), 1-8 ISSN 0953-8984 R&D Projects: GA ČR GPP204/10/P331; GA MŠk ME09048; GA AV ČR IAA100100903 Institutional research plan: CEZ:AV0Z10100521 Keywords : epitaxy * nucleation * island density * graphene * long-range interaction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.355, year: 2012

  5. Plasma surface interactions at the JET X-point tiles

    International Nuclear Information System (INIS)

    Martinelli, A.P.; Behrisch, R.; Coad, J.P.; Kock, L. de

    1989-01-01

    Operation with a magnetic divertor, which leads to a zero poloidal field inside the volume of the discharge vessel (the X-point) has led to substantial improvements in confinement time in JET. In this mode the diverted plasma is conducted to a large number of graphite tiles (X-point tiles) near the top of the vessel. The power handling capability of these tiles limits the maximum additional heating power to the discharge. The study of the surface modifications of the X-point tiles of JET is therefore of interest both to correlate the magnetic configuration and plasma particle and energy fluxes with the surface modifications, and also to get information about the erosion and deposition at these wall areas. (author) 5 refs., 4 figs

  6. Effective medium potentials for molecule-surface interactions: H2 on Cu and Ni surfaces

    DEFF Research Database (Denmark)

    Nørskov, Jens Kehlet

    1989-01-01

    outside metal surfaces and the applicability is illustrated for H2 adsorbing on various Cu and Ni surfaces. Although very approximate, the calculated potentials seem to include a number of features observed experimentally: Ni is more active in dissociating H2 than Cu, and open surfaces are more active...... than close-packed ones. Moreover, the method is simple enough that one can contemplate studying variations in dissociation pathways over the surface unit cell. For the Cu surfaces these variations are substantial accounting for at least part of the variation of the sticking coefficient with the kinetic...

  7. Interaction of propylene with reduced surface of chromium molybdate

    International Nuclear Information System (INIS)

    Konovalova, N.D.; Belokopytov, Yu.V.

    1978-01-01

    It has been found that reduction of oxidated chromium molybdate sample by propylene at 450 deg C does not change the form of energy surface heterogeneity and also practically does not effect activation desorption energy of C 3 H 6 . It is shown that oxygen of this catalyst volume is movable and is responsible for formation of products of C 3 H 6 partial oxidation (acetic aldehyde and acrolein) in the sample reduction by propylene

  8. Dust generation at interaction of plasma jet with surfaces

    Science.gov (United States)

    Ticos, Catalin; Toader, Dorina; Banu, Nicoleta; Scurtu, Adrian; Oane, Mihai

    2013-10-01

    Coatings of W and C with widths of a few microns will be exposed to plasma jet for studying the erosion of the surface and detachment of micron size dust particles. A coaxial plasma gun has been built inside a vacuum chamber for producing supersonic plasma jets. Its design is based on a 50 kJ coaxial plasma gun which has been successfully used for accelerating hypervelocity dust. Initial shots were carried out for a capacitor bank with C = 12 μF and charged up to 2 kV. Currents of tens of amps were measured with a Rogowsky coil and plasma flow speeds of 4 km/s were inferred from high-speed images of jet propagation. An upgrade consisting in adding capacitors in parallel will be performed in order to increase the energy up to 2 kJ. A coil will be installed at the gun muzzle to compress the plasma flow and increase the energy density of the jet on the sample surface. A CCD camera with a maximum recording speed of 100 k fps and a maximum resolution of 1024 × 1024 pixels was set for image acquisition of the plasma and dust. A laser system used to illuminate the ejected dust from the surface includes a laser diode emitting at 650 nm with a beam power of 25 mW. The authors acknowledge support from EURATOM WP13-IPH-A03-P2-02-BS22.

  9. Interaction of energetic particles with polymer surfaces: surface morphology development and sputtered polymer-fragment ion analysis

    International Nuclear Information System (INIS)

    Michael, R.S.

    1987-01-01

    The core of this thesis is based on a series of papers that have been published or will soon be published in which the various processes taking place in the energetic particle-polymer surface interaction scene is investigated. Results presented show different developments on polymer surfaces when compared to the vast experimental data on energetic particle-metal surface interactions. The surface morphology development depends on the physical characteristics of the polymer. Sputtering yields of fluoropolymers were several orders higher than the sputtering yields of aliphatic and aromatic polymers. Depending on the chemical nature of the polymer, the surface morphology development was dependent upon the extent of radiation-damage accumulation. Fast Atom Bombardment Mass Spectrometry at low and high resolution was applied to the characterization of sputtered polymer fragment ions. Fragment ions and their intensities were used to identify polymer samples, observe radiation damage accumulation and probe polymer-polymer interface of a polymer-polymer sandwich structure. A model was proposed which attempts to explain the nature of processes involved in the energetic particle-polymer surface interaction region

  10. The interaction of low energy ion beams with surfaces

    International Nuclear Information System (INIS)

    Carter, G.; Armour, D.G.

    1981-01-01

    Four of the most important physical processes which occur during ion plating and allied techniques (1) ion-induced (and energetic-atom-induced) desorption of adsorbed impurities from the substrate surface, (2) ion penetration and entrapment in the substrate and coating, (3) ion-induced sputtering of substrate and coating atoms and (4) recoil displacement of substrate and coating atoms leading to their intermixing. The ion and energetic atom energy range of importance is from thermal energies to the order of 1keV. Current understanding of these processes, supported by discussion of available experimental data, is reviewed. (Auth.)

  11. Understanding small biomolecule-biomaterial interactions: a review of fundamental theoretical and experimental approaches for biomolecule interactions with inorganic surfaces.

    Science.gov (United States)

    Costa, Dominique; Garrain, Pierre-Alain; Baaden, Marc

    2013-04-01

    Interactions between biomolecules and inorganic surfaces play an important role in natural environments and in industry, including a wide variety of conditions: marine environment, ship hulls (fouling), water treatment, heat exchange, membrane separation, soils, mineral particles at the earth's surface, hospitals (hygiene), art and buildings (degradation and biocorrosion), paper industry (fouling) and more. To better control the first steps leading to adsorption of a biomolecule on an inorganic surface, it is mandatory to understand the adsorption mechanisms of biomolecules of several sizes at the atomic scale, that is, the nature of the chemical interaction between the biomolecule and the surface and the resulting biomolecule conformations once adsorbed at the surface. This remains a challenging and unsolved problem. Here, we review the state of art in experimental and theoretical approaches. We focus on metallic biomaterial surfaces such as TiO(2) and stainless steel, mentioning some remarkable results on hydroxyapatite. Experimental techniques include atomic force microscopy, surface plasmon resonance, quartz crystal microbalance, X-ray photoelectron spectroscopy, fluorescence microscopy, polarization modulation infrared reflection absorption spectroscopy, sum frequency generation and time of flight secondary ion mass spectroscopy. Theoretical models range from detailed quantum mechanical representations to classical forcefield-based approaches. Copyright © 2012 Wiley Periodicals, Inc.

  12. Measurements of long-range interactions between protein-functionalized surfaces by total internal reflection microscopy.

    Science.gov (United States)

    Wang, Zhaohui; Gong, Xiangjun; Ngai, To

    2015-03-17

    Understanding the interaction between protein-functionalized surfaces is an important subject in a variety of protein-related processes, ranging from coatings for biomedical implants to targeted drug carriers and biosensors. In this work, utilizing a total internal reflection microscope (TIRM), we have directly measured the interactions between micron-sized particles decorated with three types of common proteins concanavalin A (ConA), bovine serum albumin (BSA), lysozyme (LYZ), and glass surface coated with soy proteins (SP). Our results show that the protein adsorption greatly affects the charge property of the surfaces, and the interactions between those protein-functionalized surfaces depend on solution pH values. At pH 7.5-10.0, all these three protein-functionalized particles are highly negatively charged, and they move freely above the negatively charged SP-functionalized surface. The net interaction between protein-functionalized surfaces captured by TIRM was found as a long-range, nonspecific double-layer repulsion. When pH was decreased to 5.0, both protein-functionalized surfaces became neutral and double-layer repulsion was greatly reduced, resulting in adhesion of all three protein-functionalized particles to the SP-functionalized surface due to the hydrophobic attraction. The situation is very different at pH = 4.0: BSA-decorated particles, which are highly charged, can move freely above the SP-functionalized surfaces, while ConA- and LYZ-decorated particles can only move restrictively in a limited range. Our results quantify these nonspecific kT-scale interactions between protein-functionalized surfaces, which will enable the design of surfaces for use in biomedical applications and study of biomolecular interactions.

  13. GSFLOW model simulations used to evaluate the impact of irrigated agriculture on surface water - groundwater interaction

    Data.gov (United States)

    Department of the Interior — Watershed-scale coupled surface water (SW) – groundwater (GW) flow modeling was used to examine changes in streamflow and SW – GW interaction resulting from...

  14. The surface chemistry determines the spatio-temporal interaction dynamics of quantum dots in atherosclerotic lesions.

    Science.gov (United States)

    Uhl, Bernd; Hirn, Stephanie; Mildner, Karina; Coletti, Raffaele; Massberg, Steffen; Reichel, Christoph A; Rehberg, Markus; Zeuschner, Dagmar; Krombach, Fritz

    2018-03-01

    To optimize the design of nanoparticles for diagnosis or therapy of vascular diseases, it is mandatory to characterize the determinants of nano-bio interactions in vascular lesions. Using ex vivo and in vivo microscopy, we analyzed the interactive behavior of quantum dots with different surface functionalizations in atherosclerotic lesions of ApoE-deficient mice. We demonstrate that quantum dots with different surface functionalizations exhibit specific interactive behaviors with distinct molecular and cellular components of the injured vessel wall. Moreover, we show a role for fibrinogen in the regulation of the spatio-temporal interaction dynamics in atherosclerotic lesions. Our findings emphasize the relevance of surface chemistry-driven nano-bio interactions on the differential in vivo behavior of nanoparticles in diseased tissue.

  15. Ab initio theory of magnetic interactions at surfaces

    International Nuclear Information System (INIS)

    Sousa, C; Graaf, C de; Lopez, N; Harrison, N M; Illas, F

    2004-01-01

    The low to high spin energy transition of Ni adsorbed on regular and defective sites of MgO(100) and the relative strengths of bulk and surface magnetic coupling constants of first row transition metal oxides (MnO, FeO, CoO, NiO and CuO) are taken as examples to illustrate some deficiencies of density functional theory (DFT). For these ionic systems a cluster/periodic comparison within the same computational method (either DFT or Hartree-Fock) is used to establish that embedded cluster models provide an adequate representation. The cluster model approach is then used to obtain accurate values for the magnetic properties of interest by using explicitly correlated wavefunction methods which handle the electronic open shell rigorously as spin eigenfunctions

  16. Interactions between bubble formation and heating surface in nucleate boiling

    International Nuclear Information System (INIS)

    Luke, Andrea

    2009-01-01

    The heat transfer and bubble formation is investigated in pool boiling of propane. Size distributions of active nucleation sites on single horizontal copper and steel tubes with different diameter and surface finishes have been calculated from heat transfer measurements over wide ranges of heat flux and selected pressure. The model assumptions of Luke and Gorenflo for the heat transfer near growing and departing bubbles, which were applied in the calculations, have been slightly modified and the calculated results have been compared to experimental investigations by high speed video techniques. The calculated number of active sites shows a good coincidence for the tube with smaller diameter, while the results for the tube with larger diameter describe the same relative increase of the active sites. The comparison of the cumulative size distribution of the active and potential nucleation sites demonstrates the same slope of the curve and that the critical radius of a stable bubble nuclei is smaller than the average cavity size. (author)

  17. INTERACTION OF IMPULSE ELECTROMAGNETIC FIELDS WITH SURFACES OF METAL SAMPLES

    Directory of Open Access Journals (Sweden)

    V. V. Pavliouchenko

    2006-01-01

    Full Text Available Measurements of maximum tangential component of magnetic intensity Hτm have been carried out in the paper. The measurements have been taken on the surface of metal samples according to time of single current pulse rise in the form of semi-sinusoid of a linear current wire. Measurements have been made with the purpose to determine a value of the component according to thickness of samples made of aluminium.Temporary resolution ranges of electric and magnetic properties and defects of sample continuity along the depth have been found.Empirical formulae of dependence Hτm on sample thickness have been derived and their relation with efficient depth penetration of magnetic field into metal has been found.

  18. Terahertz instability of surface optical-phonon polaritons that interact with surface plasmon polaritons in the presence of electron drift

    International Nuclear Information System (INIS)

    Sydoruk, O.; Solymar, L.; Shamonina, E.; Kalinin, V.

    2010-01-01

    Traveling-wave interaction between optical phonons and electrons drifting in diatomic semiconductors has potential for amplification and generation of terahertz radiation. Existing models of this interaction were developed for infinite materials. As a more practically relevant configuration, we studied theoretically a finite semiconductor slab surrounded by a dielectric. This paper analyzes the optical-phonon instability in the slab including the Lorentz force and compares it to the instability in an infinite material. As the analysis shows, the slab instability occurs because of the interaction of surface optical-phonon polaritons with surface plasmon polaritons in the presence of electron drift. The properties of the instability depend on the slab thickness when the thickness is comparable to the wavelength. For large slab thicknesses, however, the dispersion relation of the slab is similar to that of an infinite material, although the coupling is weaker. The results could be used for the design of practical terahertz traveling-wave oscillators and amplifiers.

  19. Interactions between Parenteral Lipid Emulsions and Container Surfaces.

    Science.gov (United States)

    Gonyon, Thomas; Tomaso, Anthony E; Kotha, Priyanka; Owen, Heather; Patel, Dipa; Carter, Phillip W; Cronin, Jim; Green, John-Bruce D

    2013-01-01

    To evaluate the relationship between changes in emulsion globule size distributions and container uptake of lipid emulsions in total nutrient admixtures. A total nutrient admixture was prepared from a commercial lipid emulsion, 20% ClinOleic®, separated into glass (borosilicate) and ethylene vinyl acetate (EVA) plastic containers, and then stored at ambient conditions for approximately 24 h. The large globule size distribution was monitored continuously for both containers, and the quantity of triglycerides associated with both containers was measured by liquid chromatography. The changes in mass of the EVA containers were also measured gravimetrically. The volume percent of globules greater than 5 microns in diameter (PFAT5) levels for an emulsion admixture in EVA containers showed a 75% reduction compared to a marginal decrease of PFAT5 when in the glass container. Extraction of the containers showed that the quantity of triglycerides associated with the EVA surfaces steadily increased with emulsion exposure time, while the glass showed a significantly lower triglyceride content compared to the EVA. Gravimetric measurements confirmed that the EVA containers gained significant mass during exposure to the emulsion admixture. A time-dependent decrease in PFAT5 values for an emulsion admixture was associated with container triglyceride absorption where EVA containers had a greater uptake than glass containers. The larger globules appear to absorb preferentially, and the admixture globule size distribution fraction represented by PFAT5 accounts for 15-20% of the total triglyceride adsorption to the container. The goal of this work is to evaluate how emulsions in total nutrition admixtures are affected by the containers within which they are stored. Specifically, the study examines how the emulsion globule size distribution in different containers is related to adsorption or absorption of the lipids onto or into the container. The admixtures were prepared from a

  20. DFT study on the interaction of TiO2 (001) surface with HCHO molecules

    Science.gov (United States)

    Wu, Guofei; Zhao, Cuihua; Guo, Changqing; Chen, Jianhua; Zhang, Yibing; Li, Yuqiong

    2018-01-01

    The interactions of formaldehyde (HCHO) molecule with TiO2 (001) surface were studied using density functional theory calculations. HCHO molecules are dissociated by the cleavage of Csbnd H bonds after adsorption on TiO2 surface. The strong interactions between HCHO melecules and TiO2 surface are largely attributed to the bonding of hydrogen of HCHO and oxygen of TiO2 surface, which is mainly from the hybridization of the H 1s, O 2p and O 2s. The newly formed Hsbnd O bonds cause the structure changes of TiO2 surface, and lead to the cleavage of Osbnd Ti bond of TiO2 surface. The Csbnd O bond that the dissociated remains of HCHO and newly formed Hsbnd O bond can be oxidized to form carbon dioxide and water in subsequent action by oxygen from the atomosphere. The charges transfer from HCHO to TiO2 surface, and the sum amount of the charges transferred from four HCHO molecules to TiO2 surface is bigger than that from one HCHO molecule to TiO2 surface due to the combined interaction of four HCHO molecules with TiO2 surface.

  1. Cellular interactions of surface modified nanoporous silicon particles.

    Science.gov (United States)

    Bimbo, Luis M; Sarparanta, Mirkka; Mäkilä, Ermei; Laaksonen, Timo; Laaksonen, Päivi; Salonen, Jarno; Linder, Markus B; Hirvonen, Jouni; Airaksinen, Anu J; Santos, Hélder A

    2012-05-21

    In this study, the self-assembly of hydrophobin class II (HFBII) on the surface of thermally hydrocarbonized porous silicon (THCPSi) nanoparticles was investigated. The HFBII-coating converted the hydrophobic particles into more hydrophilic ones, improved the particles' cell viability in both HT-29 and Caco-2 cell lines compared to uncoated particles, and enhanced the particles' cellular association. The amount of HFBII adsorbed onto the particles was also successfully quantified by both the BCA assay and a HPLC method. Importantly, the permeation of a poorly water-soluble drug, indomethacin, loaded into THCPSi particles across Caco-2 monolayers was not affected by the protein coating. In addition, (125)I-radiolabelled HFBII did not extensively permeate the Caco-2 monolayer and was found to be stably adsorbed onto the THCPSi nanoparticles incubated in pH 7.4, which renders the particles the possibility for further track-imaging applications. The results highlight the potential of HFBII coating for improving wettability, increasing biocompatibility and possible intestinal association of PSi nanoparticulates for drug delivery applications.

  2. Investigation of plasma–surface interaction at plasma beam facilities

    Energy Technology Data Exchange (ETDEWEB)

    Kurnaev, V., E-mail: kurnaev@plasma.mephi.ru [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe sh. 31, 115409 Moscow (Russian Federation); Vizgalov, I.; Gutorov, K. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe sh. 31, 115409 Moscow (Russian Federation); Tulenbergenov, T.; Sokolov, I.; Kolodeshnikov, A.; Ignashev, V.; Zuev, V.; Bogomolova, I. [Institute of Atomic Energy, National Nuclear Center the Republic of Kazakhstan, Street Krasnoarmejsky, 10, 071100 Kurchatov (Kazakhstan); Klimov, N. [SRC RF TRINITI, ul. Pushkovykh, vladenie 12, Troitsk, 142190 Moscow (Russian Federation)

    2015-08-15

    The new Plasma Beam Facility (PBF) has been put into operation for assistance in testing of plasma faced components at Material Science Kazakhstan Tokamak (KTM). PBF includes a powerful electron gun (up to 30 kV, 1 A) and a high vacuum chamber with longitudinal magnetic field coils (up to 0.2 T). The regime of high vacuum electron beam transportation is used for thermal tests with power density at the target surface up to 10 GW/m{sup 2}. The beam plasma discharge (BPD) regime with a gas-puff is used for generation of intensive ion fluxes up to 3 ⋅ 10{sup 22} m{sup −2} s{sup −1}. Initial tests of the KTM PBF’s capabilities were carried out: various discharge regimes, carbon deposits cleaning, simultaneous thermal and ion impacts on radiation cooled refractory targets. With a water-cooled target the KTM PBF could be used for high heat flux tests of materials (validated by the experiment with W mock-up at the PR-2 PBF)

  3. Interactions between protein coated particles and polymer surfaces studied with the rotating particles probe.

    Science.gov (United States)

    Kemper, M; Spridon, D; van IJzendoorn, L J; Prins, M W J

    2012-05-29

    Nonspecific interactions between proteins and polymer surfaces have to be minimized in order to control the performance of biosensors based on immunoassays with particle labels. In this paper we investigate these nonspecific interactions by analyzing the response of protein coated magnetic particles to a rotating magnetic field while the particles are in nanometer vicinity to a polymer surface. We use the fraction of nonrotating (bound) particles as a probe for the interaction between the particles and the surface. As a model system, we study the interaction of myoglobin coated particles with oxidized polystyrene surfaces. We measure the interaction as a function of the ionic strength of the solution, varying the oxidation time of the polystyrene and the pH of the solution. To describe the data we propose a model in which particles bind to the polymer by crossing an energy barrier. The height of this barrier depends on the ionic strength of the solution and two interaction parameters. The fraction of nonrotating particles as a function of ionic strength shows a characteristic shape that can be explained with a normal distribution of energy barrier heights. This method to determine interaction parameters paves the way for further studies to quantify the roles of protein coated particles and polymers in their mutual nonspecific interactions in different matrixes.

  4. XUV Spectroscopy of the Interaction of Laser-produced Plasma with Solid Surfaces

    NARCIS (Netherlands)

    Kuznetsov, A.S.; Stuik, R.; Bijkerk, Frederik; Shevelko, A.P.

    2012-01-01

    Processes of interaction of dense, laser produced plasma (LPP) with solid surfaces represent an effective tool for controlled studies of various aspects of plasma-wall interaction, for instance simulating transient events in fusion reactors or EUV light sources and source exposed materials. A wide

  5. The role of electrostatic interactions in protease surface diffusion and the consequence for interfacial biocatalysis.

    Science.gov (United States)

    Feller, Bob E; Kellis, James T; Cascão-Pereira, Luis G; Robertson, Channing R; Frank, Curtis W

    2010-12-21

    This study examines the influence of electrostatic interactions on enzyme surface diffusion and the contribution of diffusion to interfacial biocatalysis. Surface diffusion, adsorption, and reaction were investigated on an immobilized bovine serum albumin (BSA) multilayer substrate over a range of solution ionic strength values. Interfacial charge of the enzyme and substrate surface was maintained by performing the measurements at a fixed pH; therefore, electrostatic interactions were manipulated by changing the ionic strength. The interfacial processes were investigated using a combination of techniques: fluorescence recovery after photobleaching, surface plasmon resonance, and surface plasmon fluorescence spectroscopy. We used an enzyme charge ladder with a net charge ranging from -2 to +4 with respect to the parent to systematically probe the contribution of electrostatics in interfacial enzyme biocatalysis on a charged substrate. The correlation between reaction rate and adsorption was determined for each charge variant within the ladder, each of which displayed a maximum rate at an intermediate surface concentration. Both the maximum reaction rate and adsorption value at which this maximum rate occurs increased in magnitude for the more positive variants. In addition, the specific enzyme activity increased as the level of adsorption decreased, and for the lowest adsorption values, the specific enzyme activity was enhanced compared to the trend at higher surface concentrations. At a fixed level of adsorption, the specific enzyme activity increased with positive enzyme charge; however, this effect offers diminishing returns as the enzyme becomes more highly charged. We examined the effect of electrostatic interactions on surface diffusion. As the binding affinity was reduced by increasing the solution ionic strength, thus weakening electrostatic interaction, the rate of surface diffusion increased considerably. The enhancement in specific activity achieved at

  6. Improving surface acousto-optical interaction by high aspect ratio electrodes

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard; Laude, Vincent; Khelif, Abdelkrim

    2009-01-01

    The acousto-optical interaction of an optical wave confined inside a waveguide and a surface acoustic wave launched by an interdigital transducer (IDT) at the surface of a piezoelectric material is considered. The IDT with high aspect ratio electrodes supports several acoustic modes...

  7. The Surface Radiation Budget and Cloud Climate Interactions as a Part of CERES

    Science.gov (United States)

    Cess, Robert D.

    1998-01-01

    Work that has been completed is described in reprints and preprints, and summaries in terms of broad categories are given as follows: (1) The Relationship between Surface and Satellite Shortwave Radiative Fluxes; (2) Cloud-Climate Interactions in Atmospheric General Circulation Models; (3) Absorption of Shortwave radiation by clouds; (4) Clear-sky atmospheres shortwave radiation; and (5) Surface shortwave radiation measurements.

  8. Interactions of Graphene Oxide Nanomaterials with Natural Organic Matter and Metal Oxide Surfaces

    Science.gov (United States)

    Interactions of graphene oxide (GO) with silica surfaces were investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D). Both GO deposition and release were monitored on silica- and poly-l-lysine (PLL) coated surfaces as a function of GO concentration a...

  9. Study of plasma formation in CW CO2 laser beam-metal surface interaction

    Science.gov (United States)

    Azharonok, V. V.; Vasilchenko, Zh V.; Golubev, Vladimir S.; Gresev, A. N.; Zabelin, Alexandre M.; Chubrik, N. I.; Shimanovich, V. D.

    1994-04-01

    An interaction of the cw CO2 laser beam and a moving metal surface has been studied. The pulsed and thermodynamical parameters of the surface plasma were investigated by optical and spectroscopical methods. The subsonic radiation wave propagation in the erosion plasma torch has been studied.

  10. Effect of magnetic field on nonlinear interactions of electromagnetic and surface waves in a plasma layer

    International Nuclear Information System (INIS)

    Khalil, Sh.M.; El-Sherif, N.; El-Siragy, N.M.; Tanta Univ.; El-Naggar, I.A.; Alexandria Univ.

    1985-01-01

    Investigation is made for nonlinear interaction between incident radiation and a surface wave in a magnetized plasma layer. Both interacting waves are of P polarization. The generated currents and fields at combination frequencies are obtained analytically. Unlike the S-polarized interacting waves, the magnetic field affects the fundamental waves and leads to an amplification of generated waves when their frequencies approach the cyclotron frequency. (author)

  11. Interactions of light with rough dielectric surfaces - Spectral reflectance and polarimetric properties

    Science.gov (United States)

    Yon, S. A.; Pieters, C. M.

    1988-01-01

    The nature of the interactions of visible and NIR radiation with the surfaces of rock and mineral samples was investigated by measuring the reflectance and the polarization properties of scattered and reflected light for slab samples of obsidian and fine-grained basalt, prepared to controlled surface roughness. It is shown that the degree to which radiation can penetrate a surface and then scatter back out, an essential criterion for mineralogic determinations based on reflectance spectra, depends not only upon the composition of the material, but also on its physical condition such as sample grain size and surface roughness. Comparison of the experimentally measured reflectance and polarization from smooth and rough slab materials with the predicted models indicates that single Fresnel reflections are responsible for the largest part of the reflected intensity resulting from interactions with the surfaces of dielectric materials; multiple Fresnel reflections are much less important for such surfaces.

  12. Specific and non-specific interactions on non-porous carbon black surfaces

    OpenAIRE

    Andreu, A.; Stoeckli, Fritz; Bradleya, R. H.

    2008-01-01

    The interactions which occur between methanol, ethanol or propanol and the surfaces of non-porous carbon blacks with increasing levels of oxygen chemistry have been studied using adsorption isotherm analysis and immersion calorimetry. Surface oxygen has been controlled by ozone treatment and characterised using X-ray photoelectron spectroscopy, which gives a direct and quantitative measure of surface composition from first-principles, and has not yet been extensively employed in detailed carb...

  13. Interaction Between Surface Heat Budgets, Sea Surface Temperature and Deep Convection in the Tropical Western Pacific

    Science.gov (United States)

    Chou, Shu-Hsien; Chou, Ming-Dah; Lin, Po-Hsiung; Starr, David OC. (Technical Monitor)

    2002-01-01

    The surface heat budgets, sea surface temperature (SST), clouds and winds in the tropical western Pacific are analyzed and compared for the periods April-June 1998 and 1999. The spring of 1998 is in the later phase of a strong El Nino, whereas the spring of 1999 is in a period of a La Nina. The surface shortwave (SW) and longwave (LW) radiative fluxes are retrieved from Japanese Geostationary Meteorological Satellite radiance measurements, while the surface turbulent fluxes (latent and sensible heat) are derived from SSM/I-Inferred surface air humidity and winds. The SST and sea-air temperature differences are taken from NCEP/NCAR reanalysis. Deep convection is inferred from the outgoing longwave radiation of NOAA's polar-orbiting satellites. The longitudinal shift in maximum SST, deep convection and winds during El Nino and La Nina have a large impact on the spatial distribution of surface heating. Changes in clouds between these two periods have a large impact on the monthly-mean radiative heating, exceeding 60 W m(exp -2) over large oceanic regions. Similarly, the differences in wind speeds and SST have a large impact on the latent cooling, exceeding 40 W m(exp -2) over large oceanic areas. However, the maximum impacts on radiative and latent heat fluxes occur in different regions. The regions of maximum impact on radiative fluxes coincide with the regions of maximum change in clouds, whereas regions of maximum impact on turbulent heat fluxes coincide with the regions of maximum change in trade winds. The time-evolution of SST in relation to that of surface heat fluxes and winds are investigated and compared between the two El Nino and La Nina periods. In regions where wind speeds (or wind stresses) are large, the change in SST agrees well with the change in the net surface heating, indicating a deep ocean mixed layer associated with strong trade winds. On the other hand, in regions where radiative fluxes are large, the change in SST does not agree well with the

  14. Strong coupling electrostatics for randomly charged surfaces: antifragility and effective interactions.

    Science.gov (United States)

    Ghodrat, Malihe; Naji, Ali; Komaie-Moghaddam, Haniyeh; Podgornik, Rudolf

    2015-05-07

    We study the effective interaction mediated by strongly coupled Coulomb fluids between dielectric surfaces carrying quenched, random monopolar charges with equal mean and variance, both when the Coulomb fluid consists only of mobile multivalent counterions and when it consists of an asymmetric ionic mixture containing multivalent and monovalent (salt) ions in equilibrium with an aqueous bulk reservoir. We analyze the consequences that follow from the interplay between surface charge disorder, dielectric and salt image effects, and the strong electrostatic coupling that results from multivalent counterions on the distribution of these ions and the effective interaction pressure they mediate between the surfaces. In a dielectrically homogeneous system, we show that the multivalent counterions are attracted towards the surfaces with a singular, disorder-induced potential that diverges logarithmically on approach to the surfaces, creating a singular but integrable counterion density profile that exhibits an algebraic divergence at the surfaces with an exponent that depends on the surface charge (disorder) variance. This effect drives the system towards a state of lower thermal 'disorder', one that can be described by a renormalized temperature, exhibiting thus a remarkable antifragility. In the presence of an interfacial dielectric discontinuity, the singular behavior of counterion density at the surfaces is removed but multivalent counterions are still accumulated much more strongly close to randomly charged surfaces as compared with uniformly charged ones. The interaction pressure acting on the surfaces displays in general a highly non-monotonic behavior as a function of the inter-surface separation with a prominent regime of attraction at small to intermediate separations. This attraction is caused directly by the combined effects from charge disorder and strong coupling electrostatics of multivalent counterions, which dominate the surface-surface repulsion due to

  15. Spatial scales of interactions among bacteria and between bacteria and the leaf surface

    Science.gov (United States)

    Esser, Daniel S.; Leveau, Johan H.J.; Meyer, Katrin M.; Wiegand, Kerstin

    2014-01-01

    Microbial life on plant leaves is characterized by a multitude of interactions between leaf colonizers and their environment. While the existence of many of these interactions has been confirmed, their spatial scale or reach often remained unknown. In this study, we applied spatial point pattern analysis to 244 distribution patterns of Pantoea agglomerans and Pseudomonas syringae on bean leaves. The results showed that bacterial colonizers of leaves interact with their environment at different spatial scales. Interactions among bacteria were often confined to small spatial scales up to 5–20 μm, compared to interactions between bacteria and leaf surface structures such as trichomes which could be observed in excess of 100 μm. Spatial point-pattern analyses prove a comprehensive tool to determine the different spatial scales of bacterial interactions on plant leaves and will help microbiologists to better understand the interplay between these interactions. PMID:25764562

  16. Scaling relationship for surface water transport in stream networks and sub-surface flow interaction

    Science.gov (United States)

    Worman, A.

    2005-12-01

    Ground surface topography is known to control the circulation pattern of groundwater and also reflects the surface hydrological pathways through the landscape. This means that similar geometrical distributions typical to the landscape can be related physically-mathematically to the overall circulation of water and solute elements on land. Such understanding is needed in the management of water resources, especially on the watershed scale or larger. This paper outlines a theory by which we represent landscape topography in terms of its Fourier spectrum of a typical wave-function, formally relate this spectrum to the sub-surface flow of water and solute elements. Further, the stream network characteristics is analysed both in terms of the fractal distribution of individual stream lengths and the distribution of total transport distances in the watershed. Empirical relationships between the three types of distributions are established for two example watersheds in the middle and southern Sweden. Because the flow of water and solute elements in the stream network can also be described by convoluting unit solutions over the stream network, this paper describes an approach that relate lanscape topography to hydrological and geochemical circulation. The study shows that surface topography, stream network characteristics and thickness of quaternary deposits controls the circulation pattern of the deep groundwater. The water exchange is controlled by topography on both the continental scale as well as regional scale. The residence of deep groundwater in the stream network - before entering the coastal zone - is, therefore also controlled by the landscape topography.

  17. Studying groundwater and surface water interactions using airborne remote sensing in Heihe River basin, northwest China

    Directory of Open Access Journals (Sweden)

    C. Liu

    2015-05-01

    Full Text Available Managing surface water and groundwater as a unified system is important for water resource exploitation and aquatic ecosystem conservation. The unified approach to water management needs accurate characterization of surface water and groundwater interactions. Temperature is a natural tracer for identifying surface water and groundwater interactions, and the use of remote sensing techniques facilitates basin-scale temperature measurement. This study focuses on the Heihe River basin, the second largest inland river basin in the arid and semi-arid northwest of China where surface water and groundwater undergoes dynamic exchanges. The spatially continuous river-surface temperature of the midstream section of the Heihe River was obtained by using an airborne pushbroom hyperspectral thermal sensor system. By using the hot spot analysis toolkit in the ArcGIS software, abnormally cold water zones were identified as indicators of the spatial pattern of groundwater discharge to the river.

  18. The interaction of uranium metal with nitrogen oxides: The formation of an oxynitride surface layer

    Energy Technology Data Exchange (ETDEWEB)

    Carley, Albert F. [School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT (United Kingdom)], E-mail: carley@cardiff.ac.uk; Nevitt, Paul; Roussel, Paul [AWE, Aldermaston, Reading, Berks RG7 4PR (United Kingdom)

    2008-01-10

    The interaction of nitric oxide, nitrogen dioxide and nitrous oxide with a polycrystalline uranium surface has been investigated at 298 K. The surface composition and electronic structure of the developing oxide films were studied using X-ray and ultraviolet photoelectron spectroscopy. Nitrous oxide adsorbs dissociatively leaving only oxygen adsorbed on the uranium surface. Nitric oxide and nitrogen dioxide also adsorb dissociatively but in these cases both oxygen and nitrogen remain on the surface. We propose the formation of uranium oxynitride (UO{sub x}N{sub y}). For exposures >350 L the rate of reaction of NO with the oxynitride surface decreases significantly. In contrast, NO{sub 2} continues to react with the surface and a further increase in surface oxygen concentration is observed.

  19. The interaction of H2O with strained uranium metal surfaces

    International Nuclear Information System (INIS)

    Tiferet, E.; Mintz, M. H.; Zalkind, S.; Jacob, I.; Shamir, N.

    2014-01-01

    The interaction of water vapor was studied on uranium metal surfaces, with various degrees of strain (relieved by different degrees of heating). The main features of dissociation, adsorption and initial oxidation for the studied surfaces will be presented. Common to all strained surfaces, on the metal surface a full dissociation occurs, while after oxidation only on most of them the water dissociation is full and on one of them, it is only partial. The oxygen dissociation product adsorbs (with sticking coefficient decreasing with strain relief), forming clusters, for all strains, while the hydrogen product clusters only on the strain relieved and recrystallized surface. The most interesting phenomenon, revealed for these surfaces, is the inhibition of hydrogen adsorption by traces of water vapor , changing from 10% for the mostly strained (defected) surface down to 1% for the strain relieved one. The suggested mechanism for this inhibition will be discussed

  20. Biological and environmental surface interactions of nanomaterials: characterization, modeling, and prediction.

    Science.gov (United States)

    Chen, Ran; Riviere, Jim E

    2017-05-01

    The understanding of nano-bio interactions is deemed essential in the design, application, and safe handling of nanomaterials. Proper characterization of the intrinsic physicochemical properties, including their size, surface charge, shape, and functionalization, is needed to consider the fate or impact of nanomaterials in biological and environmental systems. The characterizations of their interactions with surrounding chemical species are often hindered by the complexity of biological or environmental systems, and the drastically different surface physicochemical properties among a large population of nanomaterials. The complexity of these interactions is also due to the diverse ligands of different chemical properties present in most biomacromolecules, and multiple conformations they can assume at different conditions to minimize their conformational free energy. Often these interactions are collectively determined by multiple physical or chemical forces, including electrostatic forces, hydrogen bonding, and hydrophobic forces, and calls for multidimensional characterization strategies, both experimentally and computationally. Through these characterizations, the understanding of the roles surface physicochemical properties of nanomaterials and their surface interactions with biomacromolecules can play in their applications in biomedical and environmental fields can be obtained. To quantitatively decipher these physicochemical surface interactions, computational methods, including physical, statistical, and pharmacokinetic models, can be used for either analyses of large amounts of experimental characterization data, or theoretical prediction of the interactions, and consequent biological behavior in the body after administration. These computational methods include molecular dynamics simulation, structure-activity relationship models such as biological surface adsorption index, and physiologically-based pharmacokinetic models. WIREs Nanomed Nanobiotechnol 2017

  1. Tailoring optical metamaterials to tune the atom-surface Casimir-Polder interaction.

    Science.gov (United States)

    Chan, Eng Aik; Aljunid, Syed Abdullah; Adamo, Giorgio; Laliotis, Athanasios; Ducloy, Martial; Wilkowski, David

    2018-02-01

    Metamaterials are fascinating tools that can structure not only surface plasmons and electromagnetic waves but also electromagnetic vacuum fluctuations. The possibility of shaping the quantum vacuum is a powerful concept that ultimately allows engineering the interaction between macroscopic surfaces and quantum emitters such as atoms, molecules, or quantum dots. The long-range atom-surface interaction, known as Casimir-Polder interaction, is of fundamental importance in quantum electrodynamics but also attracts a significant interest for platforms that interface atoms with nanophotonic devices. We perform a spectroscopic selective reflection measurement of the Casimir-Polder interaction between a Cs(6P 3/2 ) atom and a nanostructured metallic planar metamaterial. We show that by engineering the near-field plasmonic resonances of the metamaterial, we can successfully tune the Casimir-Polder interaction, demonstrating both a strong enhancement and reduction with respect to its nonresonant value. We also show an enhancement of the atomic spontaneous emission rate due to its coupling with the evanescent modes of the nanostructure. Probing excited-state atoms next to nontrivial tailored surfaces is a rigorous test of quantum electrodynamics. Engineering Casimir-Polder interactions represents a significant step toward atom trapping in the extreme near field, possibly without the use of external fields.

  2. Identifying the regional-scale groundwater-surface water interaction on the Sanjiang Plain, Northeast China.

    Science.gov (United States)

    Wang, Xihua; Zhang, Guangxin; Xu, Y Jun; Sun, Guangzhi

    2015-11-01

    Assessment on the interaction between groundwater and surface water (GW-SW) can generate information that is critical to regional water resource management, especially for regions that are highly dependent on groundwater resources for irrigation. This study investigated such interaction on China's Sanjiang Plain (10.9 × 10(4) km(2)) and produced results to assist sustainable regional water management for intensive agricultural activities. Methods of hierarchical cluster analysis (HCA), principal component analysis (PCA), and statistical analysis were used in this study. One hundred two water samplings (60 from shallow groundwater, 7 from deep groundwater, and 35 from surface water) were collected and grouped into three clusters and seven sub-clusters during the analyses. The PCA analysis identified four principal components of the interaction, which explained 85.9% variance of total database, attributed to the dissolution and evolution of gypsum, feldspar, and other natural minerals in the region that was affected by anthropic and geological (sedimentary rock mineral) activities. The analyses showed that surface water in the upper region of the Sanjiang Plain gained water from local shallow groundwater, indicating that the surface water in the upper region was relatively more resilient to withdrawal for usage, whereas in the middle region, there was only a weak interaction between shallow groundwater and surface water. In the lower region of the Sanjiang Plain, surface water lost water to shallow groundwater, indicating that the groundwater was vulnerable to pollution by pesticides and fertilizers from terrestrial sources.

  3. Pauli Repulsion Versus van der Waals: Interaction of Indenocorannulene with a Cu(111) Surface.

    Science.gov (United States)

    Zoppi, Laura; Stöckl, Quirin; Mairena, Anaïs; Allemann, Oliver; Siegel, Jay S; Baldridge, Kim K; Ernst, Karl-Heinz

    2018-01-18

    Modification of metal electrode surfaces with functional organic molecules is an important step toward organic electronics. The interaction of the buckybowl indenocorannulene with a Cu(111) surface and the two-dimensional self-assembly on the same surface was studied by means of scanning tunneling microscopy and dispersion-enabled density functional theory. Based on the conjecture of maximizing van der Waals interaction with the surface one would expect the indeno group to be aligned parallel to the surface. Theoretical investigations predict a nonparallel arrangement with the benzo ring of the indeno group located higher above the surface than the bowl rim connected to the indeno group. This adsorbate geometry is due to strong electronic interaction between molecule and surface, including substantial Pauli repulsion. The long-range ordered monolayer shows differences for two molecules of the unit cell in scanning tunneling microscopy contrast, suggesting either different polar alignments, and therefore a different tilt of the indeno group, or occupation of different adsorption sites.

  4. Jet-Surface Interaction - High Aspect Ratio Nozzle Test: Test Summary

    Science.gov (United States)

    Brown, Clifford A.

    2016-01-01

    The Jet-Surface Interaction High Aspect Ratio Nozzle Test was conducted in the Aero-Acoustic Propulsion Laboratory at the NASA Glenn Research Center in the fall of 2015. There were four primary goals specified for this test: (1) extend the current noise database for rectangular nozzles to higher aspect ratios, (2) verify data previously acquired at small-scale with data from a larger model, (3) acquired jet-surface interaction noise data suitable for creating verifying empirical noise models and (4) investigate the effect of nozzle septa on the jet-mixing and jet-surface interaction noise. These slides give a summary of the test with representative results for each goal.

  5. Direct measurement of colloidal interactions between polyaniline surfaces in a uv-curable coating formulation

    DEFF Research Database (Denmark)

    Jafarzadeh, Shadi; Claesson, Per M.; Pan, Jinshan

    2014-01-01

    The interactions between polyaniline particles and polyaniline surfaces in polyester acrylate resin mixed with 1,6-hexanediol diacrylate monomer have been investigated using contact angle measurements and the atomic force microscopy colloidal probe technique. Polyaniline with different characteri......The interactions between polyaniline particles and polyaniline surfaces in polyester acrylate resin mixed with 1,6-hexanediol diacrylate monomer have been investigated using contact angle measurements and the atomic force microscopy colloidal probe technique. Polyaniline with different...... cantilever and a pressed pellet of either hydrophilic or hydrophobic polyaniline powders, in resins of various polymer:monomer ratios. A short-range purely repulsive interaction was observed between hydrophilic polyaniline (doped with phosphoric acid) surfaces in polyester acrylate resin. In contrast...

  6. Enhanced printability of thermoplastic polyurethane substrates by silica particles surface interactions

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, S., E-mail: s.cruz@dep.uminho.pt [IPC/I3N – Institute of Polymers and Composites/Inst. of Nanostructures, Nanomodelling and Nanofabrication, Department Polymer Engineering, University of Minho, 4804-533 Guimarães (Portugal); Rocha, L.A. [CMEMS, University of Minho, 4804-533 Guimarães (Portugal); Viana, J.C. [IPC/I3N – Institute of Polymers and Composites/Inst. of Nanostructures, Nanomodelling and Nanofabrication, Department Polymer Engineering, University of Minho, 4804-533 Guimarães (Portugal)

    2016-01-01

    Graphical abstract: - Highlights: • A new method development for surface treatment of thermoplastic polyurethane (TPU) substrates. • The proposed method increases TPU surface energy (by 45%) and consequently the TPU wettability. • Great increase of the TPU surface roughness (by 621%). • Inkjet printed conductive ink was applied to the surface treated TPU substrate and significant improvements on the printability were obtained. - Abstract: A new method developed for the surface treatment of thermoplastic polymer substrates that increases their surface energies is introduced in this paper. The method is environmental friendly and low cost. In the proposed surface treatment method, nanoparticles are spread over the thermoplastic polyurethane (TPU) flexible substrate surface and then thermally fixed. This latter step allows the nanoparticles sinking-in on the polymer surface, resulting in a higher polymer–particle interaction at their interfacial region. The addition of nanoparticles onto the polymer surface increases surface roughness. The extent of the nanoparticles dispersion and sink-in in the substrate was evaluated through microscopy analysis (SEM). The roughness of the surface treated polymeric substrate was evaluated by AFM analysis. Substrate critical surface tension (ST) was measured by contact angle. In general, a homogeneous roughness form is achieved to a certain level. Great increase of the TPU surface roughness (by 621%) was induced by the propose method. The proposed surface treatment method increased significantly the substrate ST (by 45%) and consequently the TPU wettability. This novel surface treatment of thermoplastic polymers was applied to the inkjet printing of TPU substrates with conductive inks, and significant improvements on the printability were obtained.

  7. Protein-Nanoparticle Interactions: Improving Immobilized Lytic Enzyme Activity and Surface Energy Effects

    Science.gov (United States)

    Downs, Emily Elizabeth

    Protein-nanostructure conjugates, particularly particles, are a subject of significant interest due to changes in their fundamental behavior compared to bulk surfaces. As the size scale of nano-structured materials and proteins are on the same order of magnitude, nanomaterial properties can heavily influence how proteins adsorb and conform to the surface. Previous work has demonstrated the ability of nanoscale surfaces to modulate protein activity, conformation, and retention by modifying the particle surface curvature, morphology, and surface charge. This work has improved our understanding of the protein material interactions, but a complete understanding is still lacking. The goal of this thesis is to investigate two missing areas of understanding using two distinct systems. The first system utilizes a particle with controlled surface energy to observe the impact of surface energy on protein-particle interactions, while the second system uses a modified Listeria-specific protein to determine how protein structure and flexibility affects protein adsorption and activity on particles. Spherical, amorphous, and uniformly doped Zn-silica particles with tailored surface energies were synthesized to understand the impact of surface energy on protein adsorption behavior. Particle surface energy increased with a decrease in particle size and greater dopant concentrations. Protein adsorption and structural loss increased with both particle size and particle surface energy. Higher surface energies promoted protein-particle association and increased protein unfolding. Particle curvature and protein steric hindrance effects limited adsorption and structural loss on smaller particles. Protein surface charge heterogeneity was also found to be linked to both protein adsorption and unfolding behavior on larger particles. Greater surface charge heterogeneity led to higher adsorption concentrations and multilayer formation. These multilayers transitioned from protein

  8. Contributions of gas-phase plasma chemistry to surface modifications and gas-surface interactions: investigations of fluorocarbon rf plasmas

    Science.gov (United States)

    Cuddy, Michael F., II

    The fundamental aspects of inductively coupled fluorocarbon (FC) plasma chemistry were examined, with special emphasis on the contributions of gas-phase species to surface modifications. Characterization of the gas-phase constituents of single-source CF4-, C2F6-, C3F 8-, and C3F6-based plasmas was performed using spectroscopic and mass spectrometric techniques. The effects of varying plasma parameters, including applied rf power (P) and system pressure (p) were examined. Optical emission spectroscopy (OES) and laser-induced fluorescence (LIF) spectroscopy were employed to monitor the behavior of excited and ground CFx (x = 1,2) radicals, respectively. Mass spectrometric techniques, including ion energy analyses, elucidated behaviors of nascent ions in the FC plasmas. These gas-phase data were correlated with the net effect of substrate processing for Si and ZrO2 surfaces. Surface-specific analyses were performed for post-processed substrates via x-ray photoelectron spectroscopy (XPS) and contact angle goniometry. Generally, precursors with lower F/C ratios tended to deposit robust FC films of high surface energy. Precursors of higher F/C ratio, such as CF4, were associated with etching or removal of material from surfaces. Nonetheless, a net balance between deposition of FC moieties and etching of material exists for each plasma system. The imaging of radicals interacting with surfaces (IRIS) technique provided insight into the phenomena occurring at the interface of the plasma gas-phase and substrate of interest. IRIS results demonstrate that CFx radicals scatter copiously, with surface scatter coefficients, S, generally greater than unity under most experimental conditions. Such considerable S values imply surface-mediated production of the CFx radicals at FC-passivated sites. It is inferred that the primary route to surface production of CFx arises from energetic ion bombardment and ablation of surface FC films. Other factors which may influence the observed CFx

  9. In vitro assays of molecular motors--impact of motor-surface interactions.

    Science.gov (United States)

    Mansson, Alf; Balaz, Martina; Albet-Torres, Nuria; Rosengren, K Johan

    2008-05-01

    In many types of biophysical studies of both single molecules and ensembles of molecular motors the motors are adsorbed to artificial surfaces. Some of the most important assay systems of this type (in vitro motility assays and related single molecule techniques) will be briefly described together with an account of breakthroughs in the understanding of actomyosin function that have resulted from their use. A poorly characterized, but potentially important, entity in these studies is the mechanism of motor adsorption to surfaces and the effects of motor surface interactions on experimental results. A better understanding of these phenomena is also important for the development of commercially viable nanotechnological applications powered by molecular motors. Here, we will consider several aspects of motor surface interactions with a particular focus on heavy meromyosin (HMM) from skeletal muscle. These aspects will be related to heavy meromyosin structure and relevant parts of the vast literature on protein-surface interactions for non-motor proteins. An overview of methods for studying motor-surface interactions will also be given. The information is used as a basis for further development of a model for HMM-surface interactions and is discussed in relation to experiments where nanopatterning has been employed for in vitro reconstruction of actomyosin order. The challenges and potentials of this approach in biophysical studies, compared to the use of self-assembly of biological components into supramolecular protein aggregates (e.g. myosin filaments) will be considered. Finally, this review will consider the implications for further developments of motor-powered lab-on-a-chip devices.

  10. Challenges and opportunities of modeling plasma-surface interactions in tungsten using high-performance computing

    Science.gov (United States)

    Wirth, Brian D.; Hammond, K. D.; Krasheninnikov, S. I.; Maroudas, D.

    2015-08-01

    The performance of plasma facing components (PFCs) is critical for ITER and future magnetic fusion reactors. The ITER divertor will be tungsten, which is the primary candidate material for future reactors. Recent experiments involving tungsten exposure to low-energy helium plasmas reveal significant surface modification, including the growth of nanometer-scale tendrils of "fuzz" and formation of nanometer-sized bubbles in the near-surface region. The large span of spatial and temporal scales governing plasma surface interactions are among the challenges to modeling divertor performance. Fortunately, recent innovations in computational modeling, increasingly powerful high-performance computers, and improved experimental characterization tools provide a path toward self-consistent, experimentally validated models of PFC and divertor performance. Recent advances in understanding tungsten-helium interactions are reviewed, including such processes as helium clustering, which serve as nuclei for gas bubbles; and trap mutation, dislocation loop punching and bubble bursting; which together initiate surface morphological modification.

  11. Challenges and opportunities of modeling plasma–surface interactions in tungsten using high-performance computing

    International Nuclear Information System (INIS)

    Wirth, Brian D.; Hammond, K.D.; Krasheninnikov, S.I.; Maroudas, D.

    2015-01-01

    The performance of plasma facing components (PFCs) is critical for ITER and future magnetic fusion reactors. The ITER divertor will be tungsten, which is the primary candidate material for future reactors. Recent experiments involving tungsten exposure to low-energy helium plasmas reveal significant surface modification, including the growth of nanometer-scale tendrils of “fuzz” and formation of nanometer-sized bubbles in the near-surface region. The large span of spatial and temporal scales governing plasma surface interactions are among the challenges to modeling divertor performance. Fortunately, recent innovations in computational modeling, increasingly powerful high-performance computers, and improved experimental characterization tools provide a path toward self-consistent, experimentally validated models of PFC and divertor performance. Recent advances in understanding tungsten–helium interactions are reviewed, including such processes as helium clustering, which serve as nuclei for gas bubbles; and trap mutation, dislocation loop punching and bubble bursting; which together initiate surface morphological modification

  12. Electrical double layer interactions between dissimilar oxide surfaces with charge regulation and Stern-Grahame layers.

    Science.gov (United States)

    Chan, Derek Y C; Healy, Thomas W; Supasiti, Tharatorn; Usui, S

    2006-04-01

    Models of surfaces with intrinsic ionisable amphoteric surface sites governed by the dissociation of acid-base potential determining ion species together with the capacity for the adsorption of anion and cations of the supporting electrolyte are required to describe both the results of electrokinetic and titration measurements of inorganic oxides. The Gouy-Chapman-Stern-Grahame (CGSG) model is one such model that has been widely used in the literature. The electrical double layer interaction between two dissimilar CGSG surfaces has been studied by Usui recently [S. Usui, J. Colloid Interface Sci. 280 (2004) 113] where erroneous discontinuities in the slope of the pressure-separation relation were observed. We revisit this calculation and provide a simple general methodology to analyse the electrical double layer interaction between dissimilar ionisable surfaces with ion adsorption.

  13. Highly stable surface modification of hypercrosslinked monolithic capillary columns and their application in hydrophilic interaction chromatography.

    Science.gov (United States)

    Škeříková, Veronika; Urban, Jiří

    2013-09-01

    A two-step surface modification of poly(styrene-co-vinylbenzyl chloride-co-divinylbenzene) monolithic stationary phases, including hypercrosslinking and thermally initiated surface grafting of [2-(methacryloyloxy)ethyl]dimethyl(3-sulfopropyl)ammonium hydroxide, has been used to prepare capillary columns for the isocratic separation of small polar compounds in hydrophilic interaction chromatography (HILIC). The prepared monolithic columns provided a dual retention mechanism, combining RP and hydrophilic interaction chromatography, controlled by the composition of the mobile phase. By the optimization of the surface grafting reaction using response surface methodology, we have found that the grafting time is the main synergistic effect controlling the retention of polar compounds in HILIC. The prepared monolithic columns achieved long column lifetimes and did not lose their separation power following >10,000 injections. Finally, hypercrosslinked columns have been used in the 1- and 2D LC of phenolic compounds. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. A new facility for studying plasma interacting with flowing liquid lithium surface

    International Nuclear Information System (INIS)

    Cao, X.; Ou, W.; Tian, S.; Wang, C.; Zhu, Z.; Wang, J.; Gou, F.; Yang, D.; Chen, S.

    2014-01-01

    A new facility to study plasmas interacting with flowing liquid lithium surface was designed and is constructing in Sichuan University. The integrated setup includes the liquid lithium circulating part and linear high density plasma generator. The circulating part is consisted of main loop, on-line monitor system, lithium purification system and temperature programmed desorption system. In our group a linear high density plasma generator was built in 2012. Three coils were mounted along the vessel to produce an axial magnetic field inside. The magnetic field strength is up to 0.45 T and work continuously. Experiments on plasmas interacting with free flowing liquid lithium surface will be performed

  15. Interaction of insulin with colloidal ZnS quantum dots functionalized by various surface capping agents.

    Science.gov (United States)

    Hosseinzadeh, Ghader; Maghari, Ali; Farniya, Seyed Morteza Famil; Keihan, Amir Homayoun; Moosavi-Movahedi, Ali A

    2017-08-01

    Interaction of quantum dots (QDs) and proteins strongly influenced by the surface characteristics of the QDs at the protein-QD interface. For a precise control of these surface-related interactions, it is necessary to improve our understanding in this field. In this regard, in the present work, the interaction between the insulin and differently functionalized ZnS quantum dots (QDs) were studied. The ZnS QDs were functionalized with various functional groups of hydroxyl (OH), carboxyl (COOH), amine (NH 2 ), and amino acid (COOH and NH 2 ). The effect of surface hydrophobicity was also studied by changing the alkyl-chain lengths of mercaptocarboxylic acid capping agents. The interaction between insulin and the ZnS QDs were investigated by fluorescence quenching, synchronous fluorescence, circular dichroism (CD), and thermal aggregation techniques. The results reveal that among the studied QDs, mercaptosuccinic acid functionalized QDs has the strongest interaction (∆G ° =-51.50kJ/mol at 310K) with insulin, mercaptoethanol functionalized QDs destabilize insulin by increasing the beta-sheet contents, and only cysteine functionalized QDs improves the insulin stability by increasing the alpha-helix contents of the protein, and. Our results also indicate that by increasing the alkyl-chain length of capping agents, due to an increase in hydrophobicity of the QDs surface, the beta-sheet contents of insulin increase which results in the enhancement of insulin instability. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Single-ion and pair-interaction potentials near simple metal surfaces

    International Nuclear Information System (INIS)

    Barnett, R.N.; Barrera, R.G.; Cleveland, C.L.; Landman, U.

    1983-01-01

    Presented is a model for semi-infinite simple metals which does not require crystalline order or a single species, and thus is applicable to problems of defect energetics near the surface and random-alloy surfaces as well as ideal metal surfaces. The formulation is based on the use of ionic pseudopotentials and linear-response theory. An expression for the total energy is obtained which depends explicitly on ionic species and position. This expression is decomposed into a density-dependent term and single-ion and ionic pair-interaction potential terms. The single-ion potentials oscillate about a constant bulk value, with the magnitude of the oscillation decreasing rapidly away from the surface. The interaction between pairs of ions near the surface is shown to be a noncentral force interaction which differs significantly from the central-force bulk pair potential. The effect of quantum interference in the response of the semi-infinite electron gas to the ions is seen in both the single-ion and the pair-interaction potentials. Results are presented for the simple metals sodium, potassium, and rubidium

  17. Interaction of hydrogen and oxygen with bulk defects and surfaces of metals

    International Nuclear Information System (INIS)

    Besenbacher, F.

    1994-05-01

    The thesis deals with the interaction of hydrogen with defects in metals and the interaction of hydrogen and oxygen with metal surfaces studied by ion-beam techniques and scanning tunneling microscopy (STM), respectively. The first part of the thesis discusses the interaction of hydrogen with simple defects in transition metals. The trap-binding enthalpies and the lattice location of hydrogen trapped to vacancies have been determined, and an extremely simple and versatile picture of the hydrogen-metal interaction has evolved, in which the trap strength is mainly determined by the local electron density. Any dilution of the lattice will lead to a trap, vacancies and voids being the strongest trap. It is found that hydrogen trapped to vacancies in fcc metals is quantum-mechanically delocalized, and the excitation energies for the hydrogen in the vacancy potential are a few MeV only. The interaction of hydrogen with metal surfaces is studied by the transmission channeling (TC) technique. It is found that hydrogen chemisorbs in the highest-coordinated sites on the surfaces, and that there is a direct relationship between the hydrogen-metal bond length and the coordination number for the hydrogen. In the final part of the thesis the dynamics of the chemisorption process for oxygen and hydrogen on metal surfaces is studied by STM, a fascinating and powerful technique for exploring the atomic-scale realm of surfaces. It is found that there is a strong coupling between the chemisorption process and the distortion of the metal surface. The adsorbates induce a surface reconstruction, i.e. metal-metal bond breaks and metal-adsorbate bounds form. Whereas hydrogen interacts weakly with the metals and induces reconstructions where only nnn metals bonds are broken, oxygen interacts strongly with the metal, and the driving force for the O-induced reconstructions appears to be the formation of low-coordinated metal-O rows, formed by breaking of nn metal bonds. Finally it is shown

  18. The structure of the interface in the solvent mediated interaction of dipolar surfaces

    International Nuclear Information System (INIS)

    Dzhavakhidze, P.G.; Levadny, V.G.

    1987-08-01

    Interaction of two dipolar surfaces separated by a polar medium is considered within the framework of nonlocal electrostatics. The dipolar surface layers are modelled as regular lattices with fixed orientation of dipoles which are immersed into the solvent; solvent response is characterized by nonlocal dielectric function. The model is elaborated in order to reveal the role of the dipolar layer discreteness in the electric field produced by one surface and the interaction between two surfaces (which gives rise to the so called ''hydration'' or ''structural'' force acting between mineral surfaces and phospholipid bilayers). The discreteness effects are present only for commensurate lattices. Their special mutual arrangement then may lead to considerable reduction of structural forces, viz. the usual repulsion regime may change at short distances to attraction. Conditions are considered when repulsion is entirely replaced by attraction, i.e. the ''hydration barrier'' disappears. In appended note we discuss the role of solvation of surface dipolar groups. We propose an explanation of why two modes of decay (one with oscillative fine structure) may be present in the dependence of the force upon distance if the surface dipolar groups are immersed deep enough in the solvent and how the long-range oscillative mode disappears when the surface is but weakly solvated. (author). 35 refs, 5 figs

  19. Ion and electron beam interaction on surfaces - a detection mechanism for obtaining visual ion beam images

    International Nuclear Information System (INIS)

    Fine, J.; Gorden, R. Jr.

    1978-01-01

    Two-dimensional images have been obtained of ion beam impact cross sections on solid surfaces by the coincident interaction of a rastered electron beam. This detection method is effective in producing images in real time on various insulator surfaces. The size of these images correlates well with ion beam current density profile measurements (at full width) and, therefore, can be very useful for ion beam diagnostics and alignment. (Auth.)

  20. Interaction of SO2 with the Surface of a Water Nanodroplet.

    Science.gov (United States)

    Zhong, Jie; Zhu, Chongqin; Li, Lei; Richmond, Geraldine L; Francisco, Joseph S; Zeng, Xiao Cheng

    2017-11-29

    We present a comprehensive computational study of interaction of a SO 2 with water molecules in the gas phase and with the surface of various sized water nanodroplets to investigate the solvation behavior of SO 2 in different atmospheric environments. Born-Oppenheimer molecular dynamics (BOMD) simulation shows that, in the gas phase and at a temperature of 300 K, the dominant interaction between SO 2 and H 2 O is (SO 2 ) S···O (H 2 O) , consistent with previous density-functional theory (DFT) computation at 0 K. However, at the surface of a water nanodroplet, BOMD simulation shows that the hydrogen-bonding interaction of (SO 2 ) O···H (H 2 O) becomes increasingly important with the increase of droplet size, reflecting a marked effect of the water surface on the SO 2 solvation. This conclusion is in good accordance with spectroscopy evidence obtained previously (J. Am. Chem. Soc. 2005, 127, 16806; J. Am. Chem. Soc. 2006, 128, 3256). The prevailing interaction (SO 2 ) O···H (H 2 O) on a large droplet is mainly due to favorable exposure of H atoms of H 2 O at the air-water interface. Indeed, the conversion of the dominant interaction in the gas phase (SO 2 ) S···O (H 2 O) to the dominant interaction on the water nanodroplet (SO 2 ) O···H (H 2 O) may incur effects on the SO 2 chemistry in atmospheric aerosols because the solvation of SO 2 at the water surface can affect the reactive sites and electrophilicity of SO 2 . Hence, the solvation of SO 2 on the aerosol surface may have new implications when studying SO 2 chemistry in the aerosol-containing troposphere.

  1. Probing anisotropic surface properties and interaction forces of chrysotile rods by atomic force microscopy and rheology.

    Science.gov (United States)

    Yang, Dingzheng; Xie, Lei; Bobicki, Erin; Xu, Zhenghe; Liu, Qingxia; Zeng, Hongbo

    2014-09-16

    Understanding the surface properties and interactions of nonspherical particles is of both fundamental and practical importance in the rheology of complex fluids in various engineering applications. In this work, natural chrysotile, a phyllosilicate composed of 1:1 stacked silica and brucite layers which coil into cylindrical structure, was chosen as a model rod-shaped particle. The interactions of chrysotile brucite-like basal or bilayered edge planes and a silicon nitride tip were measured using an atomic force microscope (AFM). The force-distance profiles were fitted using the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, which demonstrates anisotropic and pH-dependent surface charge properties of brucite-like basal plane and bilayered edge surface. The points of zero charge (PZC) of the basal and edge planes were estimated to be around pH 10-11 and 6-7, respectively. Rheology measurements of 7 vol % chrysotile (with an aspect ratio of 14.5) in 10 mM NaCl solution showed pH-dependent yield stress with a local maximum around pH 7-9, which falls between the two PZC values of the edge and basal planes of the rod particles. On the basis of the surface potentials of the edge and basal planes obtained from AFM measurements, theoretical analysis of the surface interactions of edge-edge, basal-edge, and basal-basal planes of the chrysotile rods suggests the yield stress maximum observed could be mainly attributed to the basal-edge attractions. Our results indicate that the anisotropic surface properties (e.g., charges) of chrysotile rods play an important role in the particle-particle interaction and rheological behavior, which also provides insight into the basic understanding of the colloidal interactions and rheology of nonspherical particles.

  2. Impact of surface coating and food-mimicking media on nanosilver-protein interaction

    Energy Technology Data Exchange (ETDEWEB)

    Burcza, Anna, E-mail: anna.burcza@mri.bund.de; Gräf, Volker; Walz, Elke; Greiner, Ralf [Max Rubner-Institute, Department of Food Technology and Bioprocess Engineering (Germany)

    2015-11-15

    The application of silver nanoparticles (AgNPs) in food contact materials has recently become a subject of dispute due to the possible migration of silver in nanoform into foods and beverages. Therefore, the analysis of the interaction of AgNPs with food components, especially proteins, is of high importance in order to increase our knowledge of the behavior of nanoparticles in food matrices. AgPURE™ W10 (20 nm), an industrially applied nanomaterial, was compared with AgNPs of similar size frequently investigated for scientific purposes differing in the surface capping agent (spherical AgNP coated with either PVP or citrate). The interactions of the AgNPs with whey proteins (BSA, α-lactalbumin and β-lactoglobulin) at different pH values (4.2, 7 or 7.4) were investigated using surface plasmon resonance, SDS-PAGE, and asymmetric flow field-flow fractionation. The data obtained by the three different methods correlated well. Besides the nature of the protein and the nanoparticle coating, the environment was shown to affect the interaction significantly. The strongest interaction was obtained with BSA and AgNPs in an acidic environment. Neutral and slightly alkaline conditions however, seemed to prevent the AgNP-protein interaction almost completely. Furthermore, the interaction of whey proteins with AgPURE™ W10 was found to be weaker compared to the interaction with the other two AgNPs under all conditions investigated.

  3. Impact of surface coating and food-mimicking media on nanosilver-protein interaction

    International Nuclear Information System (INIS)

    Burcza, Anna; Gräf, Volker; Walz, Elke; Greiner, Ralf

    2015-01-01

    The application of silver nanoparticles (AgNPs) in food contact materials has recently become a subject of dispute due to the possible migration of silver in nanoform into foods and beverages. Therefore, the analysis of the interaction of AgNPs with food components, especially proteins, is of high importance in order to increase our knowledge of the behavior of nanoparticles in food matrices. AgPURE™ W10 (20 nm), an industrially applied nanomaterial, was compared with AgNPs of similar size frequently investigated for scientific purposes differing in the surface capping agent (spherical AgNP coated with either PVP or citrate). The interactions of the AgNPs with whey proteins (BSA, α-lactalbumin and β-lactoglobulin) at different pH values (4.2, 7 or 7.4) were investigated using surface plasmon resonance, SDS-PAGE, and asymmetric flow field-flow fractionation. The data obtained by the three different methods correlated well. Besides the nature of the protein and the nanoparticle coating, the environment was shown to affect the interaction significantly. The strongest interaction was obtained with BSA and AgNPs in an acidic environment. Neutral and slightly alkaline conditions however, seemed to prevent the AgNP-protein interaction almost completely. Furthermore, the interaction of whey proteins with AgPURE™ W10 was found to be weaker compared to the interaction with the other two AgNPs under all conditions investigated

  4. The theory of the interaction of atmospheric aerosol with underlying surface

    International Nuclear Information System (INIS)

    Buikov, M.V.

    1993-01-01

    The interaction of wind with underlying surfaces through resuspension makes a great contribution to the total amount of atmospheric aerosols. The dry deposition process results in cleaning of the atmosphere and contamination of near-surface air layers of soil and vegetation. This paper examines the theory leading to an exact solution of the problem of turbulent transportation of pollution taking into account resuspension and dry-deposition. This may be useful for the interpretation of observational data and for the improvement of calculation methods to describe aerosol exchange at surfaces in air. (author)

  5. Electron emission induced by resonant coherent ion-surface interaction at grazing incidence

    International Nuclear Information System (INIS)

    Garcia de Abajo, F.J.; Ponce, V.H.; Echenique, P.M.

    1992-01-01

    A new spectroscopy based on the resonant coherently induced electron loss to the continuum in ion-surface scattering under grazing incidence is proposed. A series of peaks, corresponding to the energy differences determined by the resonant interaction with the rows of atoms in the surface, is predicted to appear in the energy distribution of electrons emitted from electronic states bound to the probe. Calculations for MeV He + ions scattered at a W(001) surface along the left-angle 100 right-angle direction with a glancing angle of 0--2 mrad show a total yield close to 1

  6. Dispersive and Covalent Interactions between Graphene and Metal Surfaces from the Random Phase Approximation

    DEFF Research Database (Denmark)

    Olsen, Thomas; Yan, Jun; Mortensen, Jens Jørgen

    2011-01-01

    We calculate the potential energy surfaces for graphene adsorbed on Cu(111), Ni(111), and Co(0001) using density functional theory and the random phase approximation (RPA). For these adsorption systems covalent and dispersive interactions are equally important and while commonly used approximations...... for exchange-correlation functionals give inadequate descriptions of either van der Waals or chemical bonds, RPA accounts accurately for both. It is found that the adsorption is a delicate competition between a weak chemisorption minimum close to the surface and a physisorption minimum further from the surface....

  7. Fast, Statistical Model of Surface Roughness for Ion-Solid Interaction Simulations and Efficient Code Coupling

    Science.gov (United States)

    Drobny, Jon; Curreli, Davide; Ruzic, David; Lasa, Ane; Green, David; Canik, John; Younkin, Tim; Blondel, Sophie; Wirth, Brian

    2017-10-01

    Surface roughness greatly impacts material erosion, and thus plays an important role in Plasma-Surface Interactions. Developing strategies for efficiently introducing rough surfaces into ion-solid interaction codes will be an important step towards whole-device modeling of plasma devices and future fusion reactors such as ITER. Fractal TRIDYN (F-TRIDYN) is an upgraded version of the Monte Carlo, BCA program TRIDYN developed for this purpose that includes an explicit fractal model of surface roughness and extended input and output options for file-based code coupling. Code coupling with both plasma and material codes has been achieved and allows for multi-scale, whole-device modeling of plasma experiments. These code coupling results will be presented. F-TRIDYN has been further upgraded with an alternative, statistical model of surface roughness. The statistical model is significantly faster than and compares favorably to the fractal model. Additionally, the statistical model compares well to alternative computational surface roughness models and experiments. Theoretical links between the fractal and statistical models are made, and further connections to experimental measurements of surface roughness are explored. This work was supported by the PSI-SciDAC Project funded by the U.S. Department of Energy through contract DOE-DE-SC0008658.

  8. Inverse modeling of cloud-aerosol interactions -- Part 1: Detailed response surface analysis

    NARCIS (Netherlands)

    Partridge, D.G.; Vrugt, J.A.; Tunved, P.; Ekman, A.M.L.; Gorea, D.; Sooroshian, A.

    2011-01-01

    New methodologies are required to probe the sensitivity of parameters describing cloud droplet activation. This paper presents an inverse modeling-based method for exploring cloud-aerosol interactions via response surfaces. The objective function, containing the difference between the measured and

  9. The interaction of oxygen with Ni(100) and the reduction of the surface oxide by hydrogen

    NARCIS (Netherlands)

    Bokx, P.K. de; Labohm, F.; Gijzeman, O.L.J.; Bootsma, B.A.; Geus, John W.

    The interaction of oxygen with Ni(100) has been studied with ellipsometry, Auger electron spectroscopy and low energy electron diffraction. The observations of other workers are completely confirmed. The same techniques and procedures have been used to study the reduction of the surface oxide with

  10. Adhesive friction for elastic-plastic contacting rough surfaces considering asperity interaction

    International Nuclear Information System (INIS)

    Sahoo, Prasanta

    2006-01-01

    The paper describes a theoretical study of adhesive friction at the contact between rough surfaces taking asperity interaction into consideration and using an elastic-plastic model of contact deformation that is based on an accurate finite element analysis of an elastic-plastic single asperity contact. The micro-contact model of asperity interactions, developed by Zhao and Chang, is integrated into the improved elastic-plastic rough surface adhesive contact analysis to consider the adhesive friction behaviour of rough surfaces. The model considers a large range of interference values from fully elastic through elastic-plastic to fully plastic regimes of contacting asperities. Two well-established adhesion indices are used to consider different conditions that arise as a result of varying load, surface and material parameters. Results are obtained for the coefficient of friction against applied load for various combinations of these parameters. The results show that the coefficient of friction depends strongly on the applied load for the no-interaction case while it becomes insensitive to the load for interaction consideration. Moreover, the inclusion of elastic-plastic asperities further reduces the friction coefficient

  11. The interaction of trace heavy metal with lipid monolayer in the sea surface microlayer.

    Science.gov (United States)

    Li, Siyang; Du, Lin; Tsona, Narcisse T; Wang, Wenxing

    2018-04-01

    Lipid molecules and trace heavy metals are enriched in sea surface microlayer and can be transferred into the sea spray aerosol. To better understand their impact on marine aerosol generation and evolution, we investigated the interaction of trace heavy metals including Fe 3+ , Pb 2+ , Zn 2+ , Cu 2+ , Ni 2+ , Cr 3+ , Cd 2+ , and Co 2+ , with dipalmitoylphosphatidylcholine (DPPC) monolayers at the air-water interface. Phase behavior of the DPPC monolayer on heavy metal solutions was probed with surface pressure-area (π-A) isotherms. The conformation order and orientation of DPPC alkyl chains were characterized by infrared reflection-absorption spectroscopy (IRRAS). The π-A isotherms show that Zn 2+ and Fe 3+ strongly interact with DPPC molecules, and induce condensation of the monolayers in a concentration-dependent manner. IRRAS spectra show that the formation of cation-DPPC complex gives rise to conformational changes and immobilization of the headgroups. The current results suggest that the enrichment of Zn 2+ in sea spray aerosols is due to strong binding to the DPPC film. The interaction of Fe 3+ with DPPC monolayers can significantly influence their surface organizations through the formation of lipid-coated particles. These results suggest that the sea surface microlayer is capable of accumulating much higher amounts of these metals than the subsurface water. The organic and metal pollutants may transfer into the atmosphere by this interaction. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. On the bound states of Schrodinger operators with -interactions on conical surfaces

    Czech Academy of Sciences Publication Activity Database

    Lotoreichik, Vladimir; Ourmieres-Bonafos, T.

    2016-01-01

    Roč. 41, č. 6 (2016), s. 999-1028 ISSN 0360-5302 Institutional support: RVO:61389005 Keywords : conical and hyperconical surfaces * delta-interaction * existence of bound states * Schrodinger operator * spectral asymptotics Subject RIV: BE - Theoretical Physics Impact factor: 1.608, year: 2016

  13. [Studies on the interaction of blood components with ultra-smooth polymer surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, T.H. [New Mexico Univ., Albuquerque, NM (United States). School of Medicine

    1989-04-17

    This report is in three parts, though each is briefly described data is provided. The three parts address (1) radioiodination of human thrombin and fibrinogen; (2) interaction of blood components with ultra- smooth polymer surfaces; and (3) initial studies of Tecoflex and treated Tecoflex cups with normal serum samples.

  14. Spectral asymptotics of a strong delta ' interaction supported by a surface

    Czech Academy of Sciences Publication Activity Database

    Exner, Pavel; Jex, M.

    2014-01-01

    Roč. 378, 30-31 (2014), s. 2091-2095 ISSN 0375-9601 R&D Projects: GA ČR(CZ) GA14-06818S Institutional support: RVO:61389005 Keywords : delta ' surface interaction * strong coupling expansion Subject RIV: BE - Theoretical Physics Impact factor: 1.683, year: 2014

  15. Pre-evaluation and interactive editing of B-spline and GERBS curves and surfaces

    Science.gov (United States)

    Laksâ, Arne

    2017-12-01

    Interactive computer based geometry editing is very useful for designers and artists. Our goal has been to develop useful tools for geometry editing in a way that increases the ability for creative design. When we interactively editing geometry, we want to see the change happening gradually and smoothly on the screen. Pre-evaluation is a tool for increasing the speed of the graphics when doing interactive affine operation on control points and control surfaces. It is then possible to add details on surfaces, and change shape in a smooth and continuous way. We use pre-evaluation on basis functions, on blending functions and on local surfaces. Pre-evaluation can be made hierarchi-cally and is thus useful for local refinements. Sampling and plotting of curves, surfaces and volumes can today be handled by the GPU and it is therefore important to have a structured organization and updating system to be able to make interactive editing as smooth and user friendly as possible. In the following, we will show a structure for pre-evaluation and an optimal organisation of the computation and we will show the effect of implementing both of these techniques.

  16. Interactions between bacteria and solid surfaces in relation to bacterial transport in porous media

    NARCIS (Netherlands)

    Rijnaarts, H.H.M.

    1994-01-01

    Interactions between bacteria and solid surfaces strongly influence the behaviour of bacteria in natural and engineered ecosystems. Many biofilm reactors and terrestrial environments are porous media. The purpose of the research presented in this thesis is to gain a better insight into the

  17. Real/time monitoring of biomolecular interactions in blood plasma using a surface plasmon resonance biosensor

    Czech Academy of Sciences Publication Activity Database

    Špringer, Tomáš; Piliarik, Marek; Homola, Jiří

    2010-01-01

    Roč. 398, č. 5 (2010), s. 1955-1961 ISSN 1618-2642 R&D Projects: GA AV ČR KAN200670701; GA MŠk OC09058 Institutional research plan: CEZ:AV0Z20670512 Keywords : surface plasmon resonance * molecular interaction analysis * microfluidics * optical biosensor Subject RIV: BO - Biophysics Impact factor: 3.841, year: 2010

  18. Approaches to characterizing biogeochemistry effects of groundwater and surface water interaction at the riparian interface

    Science.gov (United States)

    Groundwater-surface water interaction (GSI) in riparian ecosystems strongly influences biological activity that controls nutrient flux and processes. Shallow groundwater in riparian zones is a hot spot for nitrogen removal processes, a storage zone for solutes, and a target for ...

  19. Interaction of niobium with polycrystalline palladium surface. X-ray photoemission study

    Czech Academy of Sciences Publication Activity Database

    Jirka, Ivan; Bastl, Zdeněk

    2008-01-01

    Roč. 73, č. 10 (2008), s. 1314-1326 ISSN 0010-0765 R&D Projects: GA AV ČR IAA400400625 Institutional research plan: CEZ:AV0Z40400503 Keywords : interaction * niobium * surfaces Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.784, year: 2008

  20. Interaction between Nitrous Oxide, Sevoflurane, and Opioids A Response Surface Approach

    NARCIS (Netherlands)

    Vereecke, Hugo E. M.; Proost, Johannes H.; Heyse, Bjorn; Eleveld, Douglas J.; Katoh, Takasumi; Luginbuehl, Martin; Struys, Michel M. R. F.

    Background: The interaction of sevoflurane and opioids can be described by response surface modeling using the hierarchical model. We expanded this for combined administration of sevoflurane, opioids, and 66 vol.% nitrous oxide (N2O), using historical data on the motor and hemodynamic responsiveness

  1. Comparative surface energetic study of Matrigel®and collagen I interactions with endothelial cells.

    Science.gov (United States)

    Hill, Michael J; Sarkar, Debanjan

    2017-07-01

    Understanding of the surface energetic aspects of the spontaneously deposited proteins on biomaterial surfaces and how this influences cell adhesion and differentiation is an area of regenerative medicine that has not received adequate attention. Current controversies surround the role of the biomaterial substratum surface chemistry, the range of influence of said substratum, and the effects of different surface energy components of the protein interface. Endothelial cells (ECs) are a highly important cell type for regenerative medicine applications, such as tissue engineering, and In-vivo they interact with collagen I based stromal tissue and basement membranes producing different behavioral outcomes. The surface energetic properties of these tissue types and how they control EC behavior is not well known. In this work we studied the surface energetic properties of collagen I and Matrigel ® on various previously characterized substratum polyurethanes (PU) via contact angle analysis and examined the subsequent EC network forming characteristics. A combinatorial surface energy approach was utilized that compared Zisman's critical surface tension, Kaelble's numerical method, and van Oss-Good-Chaudhury theory (vOGCT). We found that the unique, rapid network forming characteristics of ECs on Matrigel ® could be attributed to the apolar or monopolar basic interfacial characteristics according to Zisman/Kaelble or vOGCT, respectively. We also found a lack of significant substratum influence on EC network forming characteristics for Matrigel ® but collagen I showed a distinct influence where more apolar PU substrata tended to produce higher Lewis acid character collagen I interfaces which led to a greater interaction with ECs. Collagen I interfaces on more polar PU substrata lacked Lewis acid character and led to similar EC network characteristics as Matrigel ® . We hypothesized that bipolar character of the protein film favored cell-substratum over cell-cell adhesive

  2. Computational study on the interactions and orientation of monoclonal human immunoglobulin G on a polystyrene surface

    Directory of Open Access Journals (Sweden)

    Javkhlantugs N

    2013-07-01

    Full Text Available Namsrai Javkhlantugs,1,2 Hexig Bayar,3 Chimed Ganzorig,1 Kazuyoshi Ueda2 1Center for Nanoscience and Nanotechnology and Department of Chemical Technology, School of Chemistry and Chemical Engineering, National University of Mongolia, Ulaanbaatar, Mongolia; 2Department of Advanced Materials Chemistry, Graduate School of Engineering, Yokohama National University, Yokohama, Japan; 3The Key Laboratory of Mammalian Reproductive Biology and Biotechnology of the Ministry of Education, Inner Mongolia University, Hohhot, Inner Mongolia Autonomous Region, People's Republic of China Abstract: Having a theoretical understanding of the orientation of immunoglobulin on an immobilized solid surface is important in biomedical pathogen-detecting systems and cellular analysis. Despite the stable adsorption of immunoglobulin on a polystyrene (PS surface that has been applied in many kinds of immunoassays, there are many uncertainties in antibody-based clinical and biological experimental methods. To understand the binding mechanism and physicochemical interactions between immunoglobulin and the PS surface at the atomic level, we investigated the binding behavior and interactions of the monoclonal immunoglobulin G (IgG on the PS surface using the computational method. In our docking simulation with the different arrangement of translational and rotational orientation of IgG onto the PS surface, three typical orientation patterns of the immunoglobulin G on the PS surface were found. We precisely analyzed these orientation patterns and clarified how the immunoglobulin G interacts with the PS surface at atomic scale in the beginning of the adsorption process. Major driving forces for the adsorption of IgG onto the PS surface come from serine (Ser, aspartic acid (Asp, and glutamic acid (Glu residues. Keywords: bionano interface, immunoassay, polystyrene, IgG, physical adsorption, simulation

  3. AFM Colloidal Probe Measurements Implicate Capillary Condensation in Punch-Particle Surface Interactions during Tableting.

    Science.gov (United States)

    Badal Tejedor, Maria; Nordgren, Niklas; Schuleit, Michael; Millqvist-Fureby, Anna; Rutland, Mark W

    2017-11-21

    Adhesion of the powders to the punches is a common issue during tableting. This phenomenon is known as sticking and affects the quality of the manufactured tablets. Defective tablets increase the cost of the manufacturing process. Thus, the ability to predict the tableting performance of the formulation blend before the process is scaled-up is important. The adhesive propensity of the powder to the tableting tools is mostly governed by the surface-surface adhesive interactions. Atomic force microscopy (AFM) colloidal probe is a surface characterization technique that allows the measurement of the adhesive interactions between two materials of interest. In this study, AFM steel colloidal probe measurements were performed on ibuprofen, MCC (microcrystalline cellulose), α-lactose monohydrate, and spray-dried lactose particles as an approach to modeling the punch-particle surface interactions during tableting. The excipients (lactose and MCC) showed constant, small, attractive, and adhesive forces toward the steel surface after a repeated number of contacts. In comparison, ibuprofen displayed a much larger attractive and adhesive interaction increasing over time both in magnitude and in jump-in/jump-out separation distance. The type of interaction acting on the excipient-steel interface can be related to a van der Waals force, which is relatively weak and short-ranged. By contrast, the ibuprofen-steel interaction is described by a capillary force profile. Even though ibuprofen is not highly hydrophilic, the relatively smooth surfaces of the crystals allow "contact flooding" upon contact with the steel probe. Capillary forces increase because of the "harvesting" of moisture-due to the fast condensation kinetics-leaving a residual condensate that contributes to increase the interaction force after each consecutive contact. Local asperity contacts on the more hydrophilic surface of the excipients prevent the flooding of the contact zone, and there is no such adhesive

  4. Construction of Three-Dimensional Road Surface and Application on Interaction between Vehicle and Road

    Directory of Open Access Journals (Sweden)

    Lu Yongjie

    2018-01-01

    Full Text Available The quantitative description is given to three-dimensional micro and macro self-similar characteristics of road surface from the perspective of fractal geometry using FBM stochastic midpoint displacement and diamond-square algorithm in conjunction with fractal characteristics and statistical characteristics of standard pavement determined by estimation method of box-counting dimension. The comparative analysis between reconstructed three-dimensional road surface spectrum and theoretical road surface spectrum and correlation coefficient demonstrate the high reconstruction accuracy of fractal reconstructed road spectrum. Furthermore, the bump zone is taken as an example to reconstruct a more arbitrary 3D road model through isomorphism of special road surface with stochastic road surface model. Measurement is taken to assume the tire footprint on road surface to be a rectangle, where the pressure distribution is expressed with mean stiffness, while the contact points in the contact area are replaced with a number of springs. Two-DOF vehicle is used as an example to analyze the difference between three-dimensional multipoint-and-plane contact and traditional point contact model. Three-dimensional road surface spectrum provides a more accurate description of the impact effect of tire on road surface, thereby laying a theoretical basis for studies on the dynamical process of interaction of vehicle-road surface and the road friendliness.

  5. Nonperturbative theory of atom-surface interaction: corrections at short separations.

    Science.gov (United States)

    Bordag, M; Klimchitskaya, G L; Mostepanenko, V M

    2018-02-07

    The nonperturbative expressions for the free energy and force of interaction between a ground-state atom and a real-material surface at any temperature are presented. The transition to the Matsubara representation is performed, whereupon the comparison is made with the commonly used perturbative results based on the standard Lifshitz theory. It is shown that the Lifshitz formulas for the free energy and force of an atom-surface interaction follow from the nonperturbative ones in the lowest order of the small parameter. Numerical computations of the free energy and force for the atoms of He[Formula: see text] and Na interacting with a surface of an Au plate have been performed using the frequency-dependent dielectric permittivity of Au and highly accurate dynamic atomic polarizabilities in the framework of both the nonperturbative and perturbative theories. According to our results, the maximum deviations between the two theories are reached at the shortest atom-surface separations of about 1 nm. Simple analytic expressions for the atom-surface free energy are derived in the classical limit and for an ideal-metal plane. In the lowest order of the small parameter, they are found in agreement with the perturbative ones following from the standard Lifshitz theory. Possible applications of the obtained results in the theory of van der Waals adsorption are discussed.

  6. UV and IR laser radiation's interaction with metal film and teflon surfaces

    Science.gov (United States)

    Fedenev, A. V.; Alekseev, S. B.; Goncharenko, I. M.; Koval', N. N.; Lipatov, E. I.; Orlovskii, V. M.; Shulepov, M. A.; Tarasenko, V. F.

    2003-04-01

    The interaction of Xe ([lambda] [similar] 1.73 [mu]m) and XeCl (0.308 [mu]m) laser radiation with surfaces of metal and TiN-ceramic coatings on glass and steel substrates has been studied. Correlation between parameters of surface erosion versus laser-specific energy was investigated. Monitoring of laser-induced erosion on smooth polished surfaces was performed using optical microscopy. The correlation has been revealed between characteristic zones of thin coatings damaged by irradiation and energy distribution over the laser beam cross section allowing evaluation of defects and adhesion of coatings. The interaction of pulsed periodical CO2 ([lambda] [similar] 10.6 [mu]m), and Xe ([lambda] [similar] 1.73 [mu]m) laser radiation with surfaces of teflon (polytetrafluoroethylene—PTFE) has been studied. Monitoring of erosion track on surfaces was performed through optical microscopy. It has been shown that at pulsed periodical CO2-radiation interaction with teflon the sputtering of polymer with formation of submicron-size particles occurs. Dependencies of particle sizes, form, and sputtering velocity on laser pulse duration and target temperature have been obtained.

  7. Induction of subterahertz surface waves on a metal wire by intense laser interaction with a foil

    Science.gov (United States)

    Teramoto, Kensuke; Inoue, Shunsuke; Tokita, Shigeki; Yasuhara, Ryo; Nakamiya, Yoshihide; Nagashima, Takeshi; Mori, Kazuaki; Hashida, Masaki; Sakabe, Shuji

    2018-02-01

    We have demonstrated that a pulsed electromagnetic wave (Sommerfeld wave) of subterahertz frequency and 11-MV/m field strength can be induced on a metal wire by the interaction of an intense femtosecond laser pule with an adjacent metal foil at a laser intensity of 8.5 × 1018W /c m2 . The polarity of the electric field of this surface wave is opposite to that obtained by the direct interaction of the laser with the wire. Numerical simulations suggest that an electromagnetic wave associated with electron emission from the foil induces the surface wave. A tungsten wire is placed normal to an aluminum foil with a gap so that the wire is not irradiated and damaged by the laser pulse, thus making it possible to generate surface waves on the wire repeatedly.

  8. RKKY interaction in P-N junction based on surface states of 3D topological insulator

    Science.gov (United States)

    Zhang, Shuhui; Yang, Wen; Chang, Kai

    The RKKY interaction mediated by conduction electrons supplies a mechanism to realize the long-range coupling of localized spins which is desired for the spin devices. Here, we examine the controllability of RKKY interaction in P-N junction (PNJ) based on surface states of 3D topological insulator (3DTI). In this study, through quantum way but not usual classical analogy to light propagation, the intuitive picture for electron waves across the interface of PNJ is obtained, e.g., Klein tunneling, negative refraction and focusing. Moreover, we perform the numerical calculations for all kinds of RKKY interaction including the Heisenberg, Ising, and Dzyaloshinskii-Moriya terms. We find the focusing of surface states leads to the local augmentation of RKKY interaction. Most importantly, a dimension transition occurs, i.e., the decay rate of RKKY interaction from the deserved 1/R 2 to 1/ R . In addition, the quadratic gate-dependence of RKKY interaction is also beneficial to the application of 3DTI PNJ in the fields of spintronics and quantum computation. This work was supported by the MOST (Grant No. 2015CB921503, and No. 2014CB848700) and NSFC (Grant No. 11434010, No. 11274036, No. 11322542, and No. 11504018).

  9. Lactic acid bacteria in dairy food: surface characterization and interactions with food matrix components.

    Science.gov (United States)

    Burgain, J; Scher, J; Francius, G; Borges, F; Corgneau, M; Revol-Junelles, A M; Cailliez-Grimal, C; Gaiani, C

    2014-11-01

    This review gives an overview of the importance of interactions occurring in dairy matrices between Lactic Acid Bacteria and milk components. Dairy products are important sources of biological active compounds of particular relevance to human health. These compounds include immunoglobulins, whey proteins and peptides, polar lipids, and lactic acid bacteria including probiotics. A better understanding of interactions between bioactive components and their delivery matrix may successfully improve their transport to their target site of action. Pioneering research on probiotic lactic acid bacteria has mainly focused on their host effects. However, very little is known about their interaction with dairy ingredients. Such knowledge could contribute to designing new and more efficient dairy food, and to better understand relationships between milk constituents. The purpose of this review is first to provide an overview of the current knowledge about the biomolecules produced on bacterial surface and the composition of the dairy matter. In order to understand how bacteria interact with dairy molecules, adhesion mechanisms are subsequently reviewed with a special focus on the environmental conditions affecting bacterial adhesion. Methods dedicated to investigate the bacterial surface and to decipher interactions between bacteria and abiotic dairy components are also detailed. Finally, relevant industrial implications of these interactions are presented and discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Effects of fractal roughness of membrane surfaces on interfacial interactions associated with membrane fouling in a membrane bioreactor.

    Science.gov (United States)

    Feng, Shushu; Yu, Genying; Cai, Xiang; Eulade, Mahoro; Lin, Hongjun; Chen, Jianrong; Liu, Yong; Liao, Bao-Qiang

    2017-11-01

    Fractal roughness is one of the most important properties of a fractal surface. In this study, it was found that, randomly rough membrane surface was a fractal surface, which could be digitally modeled by a modified two-variable Weierstrass-Mandelbrot (WM) function. Fractal roughness of membrane surfaces has a typical power function relation with the statistical roughness of the modeled surface. Assessment of interfacial interactions showed that an increase in fractal roughness of membrane surfaces will strengthen and prolong the interfacial interactions between membranes and foulants, and under conditions in this study, will significantly increase the adhesion propensity of a foulant particle on membrane surface. This interesting result can be attributed to that increase in fractal roughness simultaneously improves separation distance and interaction surface area for adhesion of a foulant particle. This study gives deep insights into interfacial interactions and membrane fouling in MBRs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Effect of interaction of embedded crack and free surface on remaining fatigue life

    Directory of Open Access Journals (Sweden)

    Genshichiro Katsumata

    2016-12-01

    Full Text Available Embedded crack located near free surface of a component interacts with the free surface. When the distance between the free surface and the embedded crack is short, stress at the crack tip ligament is higher than that at the other area of the cracked section. It can be easily expected that fatigue crack growth is fast, when the embedded crack locates near the free surface. To avoid catastrophic failures caused by fast fatigue crack growth at the crack tip ligament, fitness-for-service (FFS codes provide crack-to-surface proximity rules. The proximity rules are used to determine whether the cracks should be treated as embedded cracks as-is, or transformed to surface cracks. Although the concepts of the proximity rules are the same, the specific criteria and the rules to transform embedded cracks into surface cracks differ amongst FFS codes. This paper focuses on the interaction between an embedded crack and a free surface of a component as well as on its effects on the remaining fatigue lives of embedded cracks using the proximity rules provided by the FFS codes. It is shown that the remaining fatigue lives for the embedded cracks strongly depend on the crack aspect ratio and location from the component free surface. In addition, it can be said that the proximity criteria defined by the API and RSE-M codes give overly conservative remaining lives. On the contrary, the WES and AME codes always give long remaining lives and non-conservative estimations. When the crack aspect ratio is small, ASME code gives non-conservative estimation.

  12. Surface modification of polyacrylonitrile-based carbon fiber and its interaction with imide

    International Nuclear Information System (INIS)

    Xu Bing; Wang Xiaoshu; Lu Yun

    2006-01-01

    In this work, sized polyacrylonitrile (PAN)-based carbon fibers were chemically modified with nitric acid and maleic anhydride (MA) in order to improve the interaction between carbon fiber surface and polyimide matrix. Bismaleimide (BMI) was selected as a model compound of polyimide to react with modified carbon fiber. The surface characteristic changing after modification and surface reaction was investigated by element analysis (EA), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and surface enhanced Raman scattering (SERS). The results indicated that the modification of carbon fiber surface with MA might follow the Diels Alder reaction mechanism. In the surface reaction between modified fibers and BMI, among the various surface functional groups, the hydroxyl group provided from phenolic hydroxyl group and bridged structure on carbon fiber may be the most effective group reacted with imide structure. The results may shed some light on the design of the appropriate surface structure, which could react with polyimide, and the manufacture of the carbon fiber-reinforced polyimide matrix composites

  13. Platelet adhesion and cellular interaction with poly(ethylene oxide) immobilized onto silicone rubber membrane surfaces.

    Science.gov (United States)

    Hsiue, G H; Lee, S D; Chang, P C

    1996-01-01

    Cellular interaction and platelet adsorption were investigated on poly(ethylene oxide) (PEO) immobilized silicone rubber membrane (SR) which has polyacrylic acid grafts on the surfaces. Polyacrylic acid (PAA) had been introduced to the SR surface after Ar plasma treatment of SR surfaces to introduce peroxide groups. Surface characterizations were made using ATR-FTIR, ESCA, SEM, and contact angle measurements. Experimental results obtained by ESCA high resolution curve fitting spectra indicated that the amount of bisamino PEO of different molecular weights immobilized onto SR surfaces were similar, which showed that the influence of the length of molecular chains (-C-C-O-) on the reactivity of terminal amino group is negligible. The wettability of modified SR surfaces increased with an increase in PEO molecular weight. Biological studies such as corneal epithelial cell culture and blood platelet adhesion were performed to understand the biocompatibility of modified SR surfaces. Biological studies using corneal epithelial cells showed that cell migration, attachment and proliferation onto PEO-20000 immobilized SR surface were suppressed, whereas these biological activities on PEO-600 were enhanced. Another study on platelet adhesion revealed that many platelets attached to PEO-600 immobilized SR, while platelet deposition was rarely observed on SR grafted with PEO-3350. The effects of different PEO molecular chains on biological response were discussed.

  14. Flavonoid-membrane Interactions: A Protective Role of Flavonoids at the Membrane Surface?

    Directory of Open Access Journals (Sweden)

    Patricia I. Oteiza

    2005-01-01

    Full Text Available Flavonoids can exert beneficial health effects through multiple mechanisms. In this paper, we address the important, although not fully understood, capacity of flavonoids to interact with cell membranes. The interactions of polyphenols with bilayers include: (a the partition of the more non-polar compounds in the hydrophobic interior of the membrane, and (b the formation of hydrogen bonds between the polar head groups of lipids and the more hydrophilic flavonoids at the membrane interface. The consequences of these interactions are discussed. The induction of changes in membrane physical properties can affect the rates of membrane lipid and protein oxidation. The partition of certain flavonoids in the hydrophobic core can result in a chain breaking antioxidant activity. We suggest that interactions of polyphenols at the surface of bilayers through hydrogen bonding, can act to reduce the access of deleterious molecules (i.e. oxidants, thus protecting the structure and function of membranes.

  15. A Multiscale Nested Modeling Framework to Simulate the Interaction of Surface Gravity Waves with Nonlinear Internal Gravity Waves

    Science.gov (United States)

    2015-09-30

    Interaction of Surface Gravity Waves with Nonlinear Internal Gravity Waves Lian Shen St. Anthony Falls Laboratory and Department of Mechanical...on studying surface gravity wave evolution and spectrum in the presence of surface currents caused by strongly nonlinear internal solitary waves...interaction of surface and internal gravity waves in the South China Sea. We will seek answers to the following questions: 1) How does the wind-wave

  16. SIgA binding to mucosal surfaces is mediated by mucin-mucin interactions.

    Directory of Open Access Journals (Sweden)

    Hannah L Gibbins

    Full Text Available The oral mucosal pellicle is a layer of absorbed salivary proteins, including secretory IgA (SIgA, bound onto the surface of oral epithelial cells and is a useful model for all mucosal surfaces. The mechanism by which SIgA concentrates on mucosal surfaces is examined here using a tissue culture model with real saliva. Salivary mucins may initiate the formation of the mucosal pellicle through interactions with membrane-bound mucins on cells. Further protein interactions with mucins may then trigger binding of other pellicle proteins. HT29 colon cell lines, which when treated with methotrexate (HT29-MTX produce a gel-forming mucin, were used to determine the importance of these mucin-mucin interactions. Binding of SIgA to cells was then compared using whole mouth saliva, parotid (mucin-free saliva and a source of purified SIgA. Greatest SIgA binding occurred when WMS was incubated with HT29-MTX expressing mucus. Since salivary MUC5B was only able to bind to cells which produced mucus and purified SIgA showed little binding to the same cells we conclude that most SIgA binding to mucosal cells occurs because SIgA forms complexes with salivary mucins which then bind to cells expressing membrane-bound mucins. This work highlights the importance of mucin interactions in the development of the mucosal pellicle.

  17. Surface mediated cooperative interactions of drugs enhance mechanical forces for antibiotic action

    Science.gov (United States)

    Ndieyira, Joseph W.; Bailey, Joe; Patil, Samadhan B.; Vögtli, Manuel; Cooper, Matthew A.; Abell, Chris; McKendry, Rachel A.; Aeppli, Gabriel

    2017-02-01

    The alarming increase of pathogenic bacteria that are resistant to multiple antibiotics is now recognized as a major health issue fuelling demand for new drugs. Bacterial resistance is often caused by molecular changes at the bacterial surface, which alter the nature of specific drug-target interactions. Here, we identify a novel mechanism by which drug-target interactions in resistant bacteria can be enhanced. We examined the surface forces generated by four antibiotics; vancomycin, ristomycin, chloroeremomycin and oritavancin against drug-susceptible and drug-resistant targets on a cantilever and demonstrated significant differences in mechanical response when drug-resistant targets are challenged with different antibiotics although no significant differences were observed when using susceptible targets. Remarkably, the binding affinity for oritavancin against drug-resistant targets (70 nM) was found to be 11,000 times stronger than for vancomycin (800 μM), a powerful antibiotic used as the last resort treatment for streptococcal and staphylococcal bacteria including methicillin-resistant Staphylococcus aureus (MRSA). Using an exactly solvable model, which takes into account the solvent and membrane effects, we demonstrate that drug-target interactions are strengthened by pronounced polyvalent interactions catalyzed by the surface itself. These findings further enhance our understanding of antibiotic mode of action and will enable development of more effective therapies.

  18. A Study on the Surface and Subsurface Water Interaction Based on the Groundwater Recession Curve

    Science.gov (United States)

    Wang, S. T.; Chen, Y. W.; Chang, L. C.; Chiang, C. J.; Wang, Y. S.

    2017-12-01

    The interaction of surface to subsurface water is an important issue for groundwater resources assessment and management. The influences of surface water to groundwater are mainly through the rainfall recharge, river recharge and discharge and other boundary sources. During a drought period, the interaction of river and groundwater may be one of the main sources of groundwater level recession. Therefore, this study explores the interaction of surface water to groundwater via the groundwater recession. During drought periods, the pumping and river interaction together are the main mechanisms causing the recession of groundwater level. In principle, larger gradient of the recession curve indicates more groundwater discharge and it is an important characteristic of the groundwater system. In this study, to avoid time-consuming manual analysis, the Python programming language is used to develop a statistical analysis model for exploring the groundwater recession information. First, the slopes of the groundwater level hydrograph at every time step were computed for each well. Then, for each well, the represented slope to each groundwater level was defined as the slope with 90% exceedance probability. The relationship between the recession slope and the groundwater level can then be obtained. The developed model is applied to Choushui River Alluvial Fan. In most wells, the results show strong positive correlations between the groundwater levels and the absolute values of the recession slopes.

  19. Integrated Modeling of Groundwater and Surface Water Interactions in a Manmade Wetland

    Directory of Open Access Journals (Sweden)

    Guobiao Huang Gour-Tsyh Yeh

    2012-01-01

    Full Text Available A manmade pilot wetland in south Florida, the Everglades Nutrient Removal (ENR project, was modeled with a physics-based integrated approach using WASH123D (Yeh et al. 2006. Storm water is routed into the treatment wetland for phosphorus removal by plant and sediment uptake. It overlies a highly permeable surficial groundwater aquifer. Strong surface water and groundwater interactions are a key component of the hydrologic processes. The site has extensive field measurement and monitoring tools that provide point scale and distributed data on surface water levels, groundwater levels, and the physical range of hydraulic parameters and hydrologic fluxes. Previous hydrologic and hydrodynamic modeling studies have treated seepage losses empirically by some simple regression equations and, only surface water flows are modeled in detail. Several years of operational data are available and were used in model historical matching and validation. The validity of a diffusion wave approximation for two-dimensional overland flow (in the region with very flat topography was also tested. The uniqueness of this modeling study is notable for (1 the point scale and distributed comparison of model results with observed data; (2 model parameters based on available field test data; and (3 water flows in the study area include two-dimensional overland flow, hydraulic structures/levees, three-dimensional subsurface flow and one-dimensional canal flow and their interactions. This study demonstrates the need and the utility of a physics-based modeling approach for strong surface water and groundwater interactions.

  20. Comparisons of the Maxwell and CLL gas/surface interaction models using DSMC

    Science.gov (United States)

    Hedahl, Marc O.; Wilmoth, Richard G.

    1995-12-01

    The behavior of two different models of gas-surface interactions is studied using the Direct Simulation Monte Carlo (DSMC) method. The DSMC calculations examine differences in predictions of aerodynamic forces and heat transfer between the Maxwell and the Cercignani-Lampis-Lord (CLL) models for flat plate configurations at freestream conditions corresponding to a 140 km orbit around Venus. The size of the flat plate represents one of the solar panels on the Magellan spacecraft, and the freestream conditions correspond to those experienced during aerobraking maneuvers. Results are presented for both a single flat plate and a two-plate configuration as a function of angle of attack and gas-surface accommodation coefficients. The two-plate system is not representative of the Magellan geometry but is studied to explore possible experiments that might be used to differentiate between the two gas-surface interaction models. The Maxwell and CLL models produce qualitatively similar results for the aerodynamic forces and heat transfer on a single flat plate. However, the flow fields produced with the two models are qualitatively different for both the single-plate and two-plate calculations. These differences in the flowfield lead to predictions of the angle of attack for maximum heat transfer in a two plate configuration that are distinctly different for the two gas-surface interactions models.

  1. Electron emission induced by resonant coherent interaction in ion-surface scattering at grazing incidence

    International Nuclear Information System (INIS)

    Garcia de Abajo, F.J.; Ponce, V.H.; Echenique, P.M.

    1994-01-01

    The resonant coherent interaction of an ion with an oriented crystal surface, under grazing-incidence conditions with respect to a special direction of the crystal, gives rise to electron loss to the continuum from electronic bound states of the ion. The calculations presented below predict large probabilities for electron emission due to this mechanism. The electrons are emitted with well defined energies, expressed in terms of the condition of resonance. Furthermore, the emission takes place around certain preferential directions, which are determined by both the latter condition and the symmetry of the surface lattice. Our calculations for MeV He + ions scattered at a W(001) surface along the left-angle 100 right-angle direction with glancing angle of 0--2 mrad indicate a yield of emission close to 1. Using heavier projectiles, one obtains smaller yields, but still large enough to be measurable in some cases (e.g., ∼0.9 for 53 MeV B 4+ and an angle of incidence of 1 mrad). Besides, the initial bound state is energy shifted due to the interaction with both the crystal potential and the velocity-dependent image potential. This results in a slight shift of the peaks of emission, which suggests a possible spectroscopy for analyzing the dynamical interaction of electronic bound states with solid surfaces

  2. Reduced PDZ Interactions of Rescued ΔF508CFTR Increases Its Cell Surface Mobility*

    Science.gov (United States)

    Valentine, Cathleen D.; Lukacs, Gergely L.; Verkman, Alan S.; Haggie, Peter M.

    2012-01-01

    Deletion of phenylalanine 508 (ΔF508) in the cystic fibrosis transmembrane conductance regulator (CFTR) plasma membrane chloride channel is the most common cause of cystic fibrosis (CF). Though several maneuvers can rescue endoplasmic reticulum-retained ΔF508CFTR and promote its trafficking to the plasma membrane, rescued ΔF508CFTR remains susceptible to quality control mechanisms that lead to accelerated endocytosis, ubiquitination, and lysosomal degradation. To investigate the role of scaffold protein interactions in rescued ΔF508CFTR surface instability, the plasma membrane mobility of ΔF508CFTR was measured in live cells by quantum dot single particle tracking. Following rescue by low temperature, chemical correctors, thapsigargin, or overexpression of GRASP55, ΔF508CFTR diffusion was more rapid than that of wild-type CFTR because of reduced interactions with PDZ domain-containing scaffold proteins. Knock-down of the plasma membrane quality control proteins CHIP and Hsc70 partially restored ΔF508CFTR-scaffold association. Quantitative comparisons of CFTR cell surface diffusion and endocytosis kinetics suggested an association between reduced scaffold binding and CFTR internalization. Our surface diffusion measurements in live cells indicate defective scaffold interactions of rescued ΔF508CFTR at the cell surface, which may contribute to its defective peripheral processing. PMID:23115232

  3. Matrix elements for level shifts and widths of hydrogenic levels in ion-surface interactions

    Energy Technology Data Exchange (ETDEWEB)

    Thumm, U.; Kuerpick, P.

    1996-05-01

    The authors present a derivation of basic one-electron matrix elements involved in the ion-metal surface scattering theory. Their method allows for the convenient generation of matrix elements for high principal quantum numbers of the projectile states and thus provides basic building blocks for the ab-initio description of highly charged ion-surface interactions. The matrix elements related to the energy shifts can be evaluated for an arbitrary one-dimensional potential therefore allowing the inclusion of electronic and nuclear self-image potentials. The authors extend these concepts to wave functions generated from an arbitrary one-dimensional surface potential and show applications to various surface potentials, projectile nuclear charges and hydrogenic levels.

  4. A combined reflectometry and quartz crystal microbalance with dissipation setup for surface interaction studies

    Science.gov (United States)

    Wang, Guoliang; Rodahl, Michael; Edvardsson, Malin; Svedhem, Sofia; Ohlsson, Gabriel; Höök, Fredrik; Kasemo, Bengt

    2008-07-01

    We have developed an instrument for surface interaction studies, which combines a newly invented four detector optical reflectometry setup with quartz crystal microbalance with dissipation (QCM-D) monitoring. The design is such that data from both techniques can be obtained simultaneously on the same sensor surface, with the same signal-to-noise ratio and time resolution, as for the individual techniques. In addition, synchronized information about structural transformations, molecular mass, and the hydration of thin films on solid surfaces can be obtained on the same specimen, as validated by monitoring the formation of supported lipid bilayers on a silica-coated QCM sensor surface. We emphasize that the optical (molecular) mass can be separated from the acoustic mass including hydrodynamically coupled solvent, which means, in turn, that the amount of solvent sensed by the QCM-D technique can be dynamically resolved during adsorption processes. In addition, the advantage/necessity to use four, compared to two, detector reflectometry is emphasized.

  5. A combined reflectometry and quartz crystal microbalance with dissipation setup for surface interaction studies

    International Nuclear Information System (INIS)

    Wang Guoliang; Ohlsson, Gabriel; Rodahl, Michael; Edvardsson, Malin; Svedhem, Sofia; Kasemo, Bengt; Hoeoek, Fredrik

    2008-01-01

    We have developed an instrument for surface interaction studies, which combines a newly invented four detector optical reflectometry setup with quartz crystal microbalance with dissipation (QCM-D) monitoring. The design is such that data from both techniques can be obtained simultaneously on the same sensor surface, with the same signal-to-noise ratio and time resolution, as for the individual techniques. In addition, synchronized information about structural transformations, molecular mass, and the hydration of thin films on solid surfaces can be obtained on the same specimen, as validated by monitoring the formation of supported lipid bilayers on a silica-coated QCM sensor surface. We emphasize that the optical (molecular) mass can be separated from the acoustic mass including hydrodynamically coupled solvent, which means, in turn, that the amount of solvent sensed by the QCM-D technique can be dynamically resolved during adsorption processes. In addition, the advantage/necessity to use four, compared to two, detector reflectometry is emphasized

  6. Tribochemical interaction between nanoparticles and surfaces of selective layer during chemical mechanical polishing

    Energy Technology Data Exchange (ETDEWEB)

    Ilie, Filip, E-mail: filip@meca.omtr.pub.ro [Polytechnic University of Bucharest, Department of Machine Elements and Tribology (Romania)

    2013-11-15

    Nanoparticles have been widely used in polish slurries such as those in the chemical mechanical polishing (CMP) process. For understanding the mechanisms of CMP, an atomic force microscope (AFM) is used to characterize polished surfaces of selective layers, after a set of polishing experiments. To optimize the CMP polishing process, one needs to get information on the interaction between the nano-abrasive slurry nanoparticles and the surface of selective layer being polished. The slurry used in CMP process of the solid surfaces is slurry with large nanoparticle size colloidal silica sol nano-abrasives. Silica sol nano-abrasives with large nanoparticle are prepared and characterized by transmission electron microscopy, particles colloidal size, and Zeta potential in this paper. The movement of nanoparticles in liquid and the interaction between nanoparticles and solid surfaces coating with selective layer are very important to obtain an atomic alloy smooth surface in the CMP process. We investigate the nanoparticle adhesion and removal processes during CMP and post-CMP cleaning. The mechanical interaction between nanoparticles and the wafer surface was studied using a microcontact wear model. This model considers the nanoparticle effects between the polishing interfaces during load balancing. Experimental results on polishing and cleaning are compared with numerical analysis. This paper suggests that during post-CMP cleaning, a combined effort in chemical and mechanical interaction (tribochemical interactions) would be effective in removal of small nanoparticles during cleaning. For large nanoparticles, more mechanical forces would be more effective. CMP results show that the removal rate has been improved to 367 nm/min and root mean square (RMS) of roughness has been reduced from 4.4 to 0.80 nm. Also, the results show that the silica sol nano-abrasives about 100 nm are of higher stability (Zeta potential is −65 mV) and narrow distribution of nanoparticle

  7. High speed cine film studies of plasma behaviour and plasma surface interactions in tokamaks

    International Nuclear Information System (INIS)

    Goodall, D.H.J.

    1982-01-01

    High speed cine photography is a useful diagnostic aid for studying plasma behaviour and plasma surface interactions. Several workers have filmed discharges in tokamaks including ASDEX, DITE, DIVA, ISX, JFT2, TFR and PLT. These films are discussed and examples given of the observed phenomena which include plasma limiter interactions, diverted discharges, disruptions, magnetic islands and moving glowing objects often known as 'UFOs'. Examples of plasma structures in ASDEX and DITE not previously published are also given. The paper also reports experiments in DITE to determine the origin of UFOs. (orig.)

  8. High speed cine film studies of plasma behaviour and plasma surface interactions in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Goodall, D.H.J. (Euratom/UKAEA Fusion Association, Abingdon (UK). Culham Lab.)

    High speed cine photography is a useful diagnostic aid for studying plasma behaviour and plasma surface interactions. Several workers have filmed discharges in tokamaks including ASDEX, DITE, DIVA, ISX, JFT2, TFR and PLT. These films are discussed and examples given of the observed phenomena which include plasma limiter interactions, diverted discharges, disruptions, magnetic islands and moving glowing objects often known as 'UFOs'. Examples of plasma structures in ASDEX and DITE not previously published are also given. The paper also reports experiments in DITE to determine the origin of UFOs.

  9. sp Carbon chain interaction with silver nanoparticles probed by Surface Enhanced Raman Scattering

    Science.gov (United States)

    Lucotti, A.; Casari, C. S.; Tommasini, M.; Li Bassi, A.; Fazzi, D.; Russo, V.; Del Zoppo, M.; Castiglioni, C.; Cataldo, F.; Bottani, C. E.; Zerbi, G.

    2009-08-01

    Surface Enhanced Raman Spectroscopy (SERS) is exploited here to investigate the interaction of isolated sp carbon chains (polyynes) in a methanol solution with silver nanoparticles. Hydrogen-terminated polyynes show a strong interaction with silver colloids used as the SERS active medium revealing a chemical SERS effect. SERS spectra after mixing polyynes with silver colloids show a noticeable time evolution. Experimental results, supported by density functional theory (DFT) calculations of the Raman modes, allow us to investigate the behavior and stability of polyynes of different lengths and the overall sp conversion towards sp 2 phase.

  10. Structure and dynamics of microbe-exuded polymers and their interactions with calcite surfaces.

    Energy Technology Data Exchange (ETDEWEB)

    Cygan, Randall Timothy; Mitchell, Ralph (Harvard University, Cambridge, MA); Perry, Thomas D. (Harvard University, Cambridge, MA)

    2005-12-01

    Cation binding by polysaccharides is observed in many environments and is important for predictive environmental modeling, and numerous industrial and food technology applications. The complexities of these organo-cation interactions are well suited to predictive molecular modeling studies for investigating the roles of conformation and configuration of polysaccharides on cation binding. In this study, alginic acid was chosen as a model polymer and representative disaccharide and polysaccharide subunits were modeled. The ability of disaccharide subunits to bind calcium and to associate with the surface of calcite was investigated. The findings were extended to modeling polymer interactions with calcium ions.

  11. The role of van der Waals interactions in the adsorption of noble gases on metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Chen, De-Li; Al-Saidi, W A; Johnson, J Karl

    2012-10-03

    Adsorption of noble gases on metal surfaces is determined by weak interactions. We applied two versions of the nonlocal van der Waals density functional (vdW-DF) to compute adsorption energies of Ar, Kr, and Xe on Pt(111), Pd(111), Cu(111), and Cu(110) metal surfaces. We have compared our results with data obtained using other density functional approaches, including the semiempirical vdW corrected DFT-D2. The vdW-DF results show considerable improvements in the description of adsorption energies and equilibrium distances over other DFTbased methods, giving good agreement with experiments. We have also calculated perpendicular vibrational energies for noble gases on the metal surfaces using vdWDF data and found excellent agreement with available experimental results. Our vdW-DF calculations show that adsorption of noble gases on low-coordination sites is energetically favored over high-coordination sites, but only by a few meV. Analysis of the 2-dimensional potential energy surface shows that the high-coordination sites are local maxima on the 2-dimensional potential energy surface and therefore unlikely to be observed in experiments, which provides an explanation of the experimental observations. The DFT-D2 approach with the standard parameterization was found to overestimate the dispersion interactions, and to give the wrong adsorption site preference for four of the nine systems we studied.

  12. Random Process Theory Approach to Geometric Heterogeneous Surfaces: Effective Fluid-Solid Interaction

    Science.gov (United States)

    Khlyupin, Aleksey; Aslyamov, Timur

    2017-06-01

    Realistic fluid-solid interaction potentials are essential in description of confined fluids especially in the case of geometric heterogeneous surfaces. Correlated random field is considered as a model of random surface with high geometric roughness. We provide the general theory of effective coarse-grained fluid-solid potential by proper averaging of the free energy of fluid molecules which interact with the solid media. This procedure is largely based on the theory of random processes. We apply first passage time probability problem and assume the local Markov properties of random surfaces. General expression of effective fluid-solid potential is obtained. In the case of small surface irregularities analytical approximation for effective potential is proposed. Both amorphous materials with large surface roughness and crystalline solids with several types of fcc lattices are considered. It is shown that the wider the lattice spacing in terms of molecular diameter of the fluid, the more obtained potentials differ from classical ones. A comparison with published Monte-Carlo simulations was discussed. The work provides a promising approach to explore how the random geometric heterogeneity affects on thermodynamic properties of the fluids.

  13. Colloquium: An algebraic model of localized surface plasmons and their interactions

    Science.gov (United States)

    Davis, T. J.; Gómez, D. E.

    2017-01-01

    Although localized surface plasmons in metal nanoparticles can be modeled by Maxwells equations, the difficulty in solving them forces many researchers to use numerical methods. Such methods give accurate results but rarely provide much insight into the complex behaviors of the surface plasmons, nor do they provide a means to choose a configuration of metal nanoparticles to achieve a desired optical response. This Colloquium presents a simple algebraic approach for modeling localized surface plasmons, their excitation by light, and their interactions with one another. Although the method is not numerically accurate it yields useful insight into plasmon behavior and provides a basis for the design of complex plasmonic devices. The approach relies on a description of the surface plasmons in terms of a set of eigenmodes. However, the functional form of these modes is not usually required and the entire problem is reduced to a simple algebra involving the plasmon amplitudes, resonance terms, and their mutual coupling. The algebraic method is derived from an electrostatic formalism, appropriate for near-field interactions at optical frequencies, which is then used to demonstrate a variety of optical effects associated with localized surface plasmons, such as plasmon hybridization, induced transparency, Fano resonances, optical phase detection, and all-optical modulation, among others.

  14. Interaction of slow and highly charged ions with surfaces: formation of hollow atoms

    Energy Technology Data Exchange (ETDEWEB)

    Stolterfoht, N.; Grether, M.; Spieler, A.; Niemann, D. [Hahn-Meitner Institut, Berlin (Germany). Bereich Festkoerperphysik; Arnau, A.

    1997-03-01

    The method of Auger spectroscopy was used to study the interaction of highly charged ions with Al and C surfaces. The formation of hollow Ne atoms in the first surface layers was evaluated by means of a Density Functional theory including non-linear screening effects. The time-dependent filling of the hollow atom was determined from a cascade model yielding information about the structure of the K-Auger spectra. Variation of total intensities of the L- and K-Auger peaks were interpreted by the cascade model in terms of attenuation effects on the electrons in the solid. (author)

  15. Modeling the process of interaction of 10 keV electrons with a plane dielectric surface

    Science.gov (United States)

    Vokhmyanina, Kristina; Sotnikova, Valentina; Sotnikov, Alexey; Kaplii, Anna; Nikulicheva, Tatyana; Kubankin, Alexandr; Kishin, Ivan

    2018-05-01

    The effect of guiding of charged particles by dielectric channels is of noticeable interest at the present time. The phenomenon is widely studied experimentally and theoretically but some points still need to be clarified. A previously developed model of interaction of fast electrons with dielectric surface at grazing incidence is used to study the independence of electron deflection on the value of electron beam current. The calculations were performed assuming a smooth dependence of the surface conductivity on the beam current in the 40-3000 nA range.

  16. Imbalance in Groundwater-Surface Water Interactions and its Relationship to the Coastal Zone Hazards

    Science.gov (United States)

    Kontar, Y. A.; Ozorovich, Y. R.; Salokhiddinov, A. T.

    2011-12-01

    We report here some efforts and results in studying the imbalance in groundwater-surface water interactions and processes of groundwater-surface water interactions and groundwater flooding creating hazards in the coastal zones. Hazards, hydrological and geophysical risk analysis related to imbalance in groundwater-surface water interactions and groundwater flooding have been to a large extent under-emphasized for coastal zone applications either due to economical limitations or underestimation of significance of imbalance in groundwater-surface water interactions. This is particularly true for tsunamis creating salt water intrusion to coastal aquifers, even though most tsunami hazard assessments have in the past relied on scenario or deterministic type models, and to increasing mineralization of potable water because of intensive water diversions and also the abundance of highly toxic pollutants (mainly pesticides) in water, air and food, which contribute to the deterioration of the coastal population's health. In the wake of pressing environmental and economic issues, it is of prime importance for the scientific community to shed light onto the great efforts by hydrologists and geophysicists to quantify conceptual uncertainties and to provide quality assurances of potential coastal zone hazard evaluation and prediction under conditions of imbalance in groundwater-surface water interactions. This paper proposes consideration of two case studies which are important and significant for future understanding of a concept of imbalance in groundwater-surface water interactions and development and essential for feasibility studies of hazards in the coastal zone. The territory of the Aral Sea Region in Central Asia is known as an ecological disaster coastal zone. It is now obvious that, in order to provide reasonable living conditions to the coastal zone population, it is first of all necessary to drastically improve the quality of the water dedicated to human needs. Due

  17. Taking advantage of reduced droplet-surface interaction to optimize transport of bioanalytes in digital microfluidics.

    Science.gov (United States)

    Freire, Sergio L S; Thorne, Nathaniel; Wutkowski, Michael; Dao, Selina

    2014-11-10

    Digital microfluidics (DMF), a technique for manipulation of droplets, is a promising alternative for the development of "lab-on-a-chip" platforms. Often, droplet motion relies on the wetting of a surface, directly associated with the application of an electric field; surface interactions, however, make motion dependent on droplet contents, limiting the breadth of applications of the technique. Some alternatives have been presented to minimize this dependence. However, they rely on the addition of extra chemical species to the droplet or its surroundings, which could potentially interact with droplet moieties. Addressing this challenge, our group recently developed Field-DW devices to allow the transport of cells and proteins in DMF, without extra additives. Here, the protocol for device fabrication and operation is provided, including the electronic interface for motion control. We also continue the studies with the devices, showing that multicellular, relatively large, model organisms can also be transported, arguably unaffected by the electric fields required for device operation.

  18. Tarantula toxins use common surfaces for interacting with Kv and ASIC ion channels.

    Science.gov (United States)

    Gupta, Kanchan; Zamanian, Maryam; Bae, Chanhyung; Milescu, Mirela; Krepkiy, Dmitriy; Tilley, Drew C; Sack, Jon T; Yarov-Yarovoy, Vladimir; Kim, Jae Il; Swartz, Kenton J

    2015-05-07

    Tarantula toxins that bind to voltage-sensing domains of voltage-activated ion channels are thought to partition into the membrane and bind to the channel within the bilayer. While no structures of a voltage-sensor toxin bound to a channel have been solved, a structural homolog, psalmotoxin (PcTx1), was recently crystalized in complex with the extracellular domain of an acid sensing ion channel (ASIC). In the present study we use spectroscopic, biophysical and computational approaches to compare membrane interaction properties and channel binding surfaces of PcTx1 with the voltage-sensor toxin guangxitoxin (GxTx-1E). Our results show that both types of tarantula toxins interact with membranes, but that voltage-sensor toxins partition deeper into the bilayer. In addition, our results suggest that tarantula toxins have evolved a similar concave surface for clamping onto α-helices that is effective in aqueous or lipidic physical environments.

  19. Bibliographic data on surface processes in particle-material interactions published in Japan, 1986-1987

    International Nuclear Information System (INIS)

    Gesi, Kazuo; Nagai, Siro; Ozawa, Kunio.

    1989-01-01

    Data on surface processes in particle-material interactions for fusion technology have been surveyed and collected over 24 publications which have been published during January, 1986 - December, 1987 in Japan. The bibliographic data in the form of data sheets were sent to the International Data Center in IAEA. This report presents 97 selected data sheets arranged in the order of codes of relevant phenomena. A list of literature is given. (author) 159 refs

  20. Reflectivity reduction of retro-reflector installed in LHD due to plasma surface interaction

    International Nuclear Information System (INIS)

    Yoshida, N.; Ohtawa, Y.; Ebihara, A.; Akiyama, T.; Tokitani, M.; Ashikawa, N.; Kawahata, K.

    2008-10-01

    Optical reflectivity of the retro-reflector installed in LHD as the first mirror was reduced seriously by plasma wall interaction. In order to understand the mechanism of the reflectivity reduction, optical and material properties of the mirror surfaces have been examined extensively. It was found that the deposited impurity layers caused the serious reduction of the reflectivity. Formation of iron oxide, bulges structure and He bubbles are the major factors for the reflectivity reduction in the wide wave length range. (author)

  1. Sensitivity analysis of the surface water- groundwater interaction for the sandy area of the Netherlands

    OpenAIRE

    Gomez del Campo, E.; Jousma, G.; Massop, H.T.L.

    1993-01-01

    The "Sensitivity Analysis of the Surface Water- Groundwater Interaction for the Sandy Area of the Netherlands" was carried out in the framework of a bilateral research project in support of the implementation of a nationwide geohydrological information system (REGIS) in the Netherlands. This project, conducted in cooperation between the TNO Institute for Applied Scientific Research (IGG-TNO) and !he Winand Staring Centre for Integrated Land, Soil and Water Research (SC-DLO), is aimed at defin...

  2. Controlling the Electronic Structure of Graphene Using Surface-Adsorbate Interactions

    Science.gov (United States)

    2015-07-21

    able to achieve relatively good control over the concentration of defects in graphene by introducing oxide impurities into the Ni(111) substrate and...1 Controlling the electronic structure of graphene using surface-adsorbate interactions Piotr Matyba, Adra V. Carr, Cong Chen, David L. Miller...atomic orbitals in graphene on Ni(111) opens a large energy gap of ≈2.8 eV between non-hybridized states at the K-point. Here we use alkali metal

  3. Rupture Dynamics along Thrust Dipping Fault: Inertia Effects due to Free Surface Wave Interactions

    Science.gov (United States)

    Vilotte, J. P.; Scala, A.; Festa, G.

    2017-12-01

    We numerically investigate the dynamic interaction between free surface and up-dip, in-plane rupture propagation along thrust faults, under linear slip-weakening friction. With reference to shallow along-dip rupture propagation during large subduction earthquakes, we consider here low dip-angle fault configurations with fixed strength excess and depth-increasing initial stress. In this configuration, the rupture undergoes a break of symmetry with slip-induced normal stress perturbations triggered by the interaction with reflected waves from the free surface. We found that both body-waves - behind the crack front - and surface waves - at the crack front - can trigger inertial effects. When waves interact with the rupture before this latter reaches its asymptotic speed, the rupture can accelerate toward the asymptotic speed faster than in the unbounded symmetric case, as a result of these inertial effects. Moreover, wave interaction at the crack front also affects the slip rate generating large ground motion on the hanging wall. Imposing the same initial normal stress, frictional strength and stress drop while varying the static friction coefficient we found that the break of symmetry makes the rupture dynamics dependent on the absolute value of friction. The higher the friction the stronger the inertial effect both in terms of rupture acceleration and slip amount. When the contact condition allows the fault interface to open close to the free surface, the length of the opening zone is shown to depend on the propagation length, the initial normal stress and the static friction coefficient. These new results are shown to agree with analytical results of rupture propagation in bounded media, and open new perspectives for understanding the shallow rupture of large subduction earthquakes and tsunami sources.

  4. Nonlinear radiation of waves at combination frequencies due to radiation-surface wave interaction in plasmas

    International Nuclear Information System (INIS)

    El Naggar, I.A.; Hussein, A.M.; Khalil, Sh.M.

    1992-09-01

    Electromagnetic waves radiated with combination frequencies from a semi-bounded plasma due to nonlinear interaction of radiation with surface wave (both of P-polarization) has been investigated. Waves are radiated both into vacuum and plasma are found to be P-polarized. We take into consideration the continuity at the plasma boundary of the tangential components of the electric field of the waves. The case of normal incidence of radiation and rarefield plasma layer is also studied. (author). 7 refs

  5. Surface Chemistry Interactions of Cationorm with Films by Human Meibum and Tear Film Compounds

    Directory of Open Access Journals (Sweden)

    Georgi As. Georgiev

    2017-07-01

    Full Text Available Cationorm® (CN cationic nanoemulsion was demonstrated to enhance tear film (TF stability in vivo possibly via effects on tear film lipid layer (TFLL. Therefore the interactions of CN with human meibum (MGS and TFLL in vitro and in vivo deserve special study. MGS and CN were spread at the air/water interface of a Langmuir surface balance to ensure a range of MGS/CN oil phase ratios: 20/1, 10/1, 5/1, 3/1, 2/1 and 1/1. The films capability to reorganize during dynamic area changes was evaluated via the surface pressure-area compression isotherms and step/relaxation dilatational rheology studies. Films structure was monitored with Brewster angle microscopy. CN/TFLL interactions at the ocular surface were monitored with non-contact specular microscopy. The in vitro studies of MGS/CN layers showed that (i CN inclusion (at fixed MGS content increased film elasticity and thickness and that (ii CN can compensate for moderate meibum deficiency in MGS/CN films. In vivo CN mixed with TFLL in a manner similar to CN/MGS interactions in vitro, and resulted in enhanced thickness of TFLL. In vitro and in vivo data complement each other and facilitated the study of the composition-structure-function relationship that determines the impact of cationic nanoemulsions on TF.

  6. Cell-surface interactions involving immobilized magnetite nanoparticles on flat magnetic substrates.

    Science.gov (United States)

    Loichen, Juliane; Hartmann, Uwe

    2009-09-01

    A new method to affect cells by cell-surface interaction is introduced. Biocompatible magnetic nanobeads are deposited onto a biocompatible magnetic thin layer. The particles are composed of small magnetite crystals embedded in a matrix which can be functionalized by different molecules, proteins or growth factors. The magnetic interaction between surface and beads prevents endocytosis if the setup is utilized for cell culturing. The force acting between particles and magnetic layer is calculated by a magnetostatic approach. Biocompatibility is ensured by using garnet layers which turned out to be nontoxic and stable under culturing conditions. The garnet thin films exhibit spatially and temporally variable magnetic domain configurations in changing external magnetic fields and depending on their thermal pretreatment. Several patterns and bead deposition methods as well as the cell-surface interactions were analyzed. In some cases the cells show directed growth. Theoretical considerations explaining particular cell behavior on this magnetic material involve calculations of cell growth on elastic substrates and bending of cell membranes.

  7. Nanophotonic force microscopy: characterizing particle-surface interactions using near-field photonics.

    Science.gov (United States)

    Schein, Perry; Kang, Pilgyu; O'Dell, Dakota; Erickson, David

    2015-02-11

    Direct measurements of particle-surface interactions are important for characterizing the stability and behavior of colloidal and nanoparticle suspensions. Current techniques are limited in their ability to measure pico-Newton scale interaction forces on submicrometer particles due to signal detection limits and thermal noise. Here we present a new technique for making measurements in this regime, which we refer to as nanophotonic force microscopy. Using a photonic crystal resonator, we generate a strongly localized region of exponentially decaying, near-field light that allows us to confine small particles close to a surface. From the statistical distribution of the light intensity scattered by the particle we are able to map out the potential well of the trap and directly quantify the repulsive force between the nanoparticle and the surface. As shown in this Letter, our technique is not limited by thermal noise, and therefore, we are able to resolve interaction forces smaller than 1 pN on dielectric particles as small as 100 nm in diameter.

  8. Surface Interaction of Nanoscale Water Film with SDS from Computational Simulation and Film Thermodynamics

    Directory of Open Access Journals (Sweden)

    Tiefeng Peng

    2017-11-01

    Full Text Available Foam systems have been attracting extensive attention due to their importance in a variety of applications, e.g., in the cleaning industry, and in bubble flotation. In the context of flotation chemistry, flotation performance is strongly affected by bubble coalescence, which in turn relies significantly on the surface forces upon the liquid film between bubbles. Conventionally, unusual short-range strongly repulsive surface interactions for Newton black films (NBF between two interfaces with thickness of less than 5 nm were not able to be incorporated into the available classical Derjaguin, Landau, Verwey, and Overbeek (DLVO theory. The non-DLVO interaction would increase exponentially with the decrease of film thickness, as it plays a crucial role in determining liquid film stability. However, its mechanism and origin are still unclear. In the present work, we investigate the surface interaction of free-standing sodium dodecyl-sulfate (SDS nanoscale black films in terms of disjoining pressure using the molecular simulation method. The aqueous nanoscale film, consisting of a water coating with SDS surfactants, and with disjoining pressure and film tension of SDS-NBF as a function of film thickness, were quantitatively determined by a post-processing technique derived from film thermodynamics.

  9. Competing interactions of noble metals and fullerenes with the Si(111)7x7 surface

    International Nuclear Information System (INIS)

    O'Shea, J.N.; Phillips, M.A.; Taylor, M.D.R.; Beton, P.H.; Moriarty, P.; Kanai, M.; Dennis, T.S.J.; Dhanak, V.R.

    2004-01-01

    Full text: Synchrotron-based photoelectron spectroscopy (PES) has been used to investigate the interaction of atomic gold and silver with a covalently bound C 60 -monolayer adsorbed on Si(111)7x7. In contrast to the relatively benign interaction of silver with the C 60 /Si(111)7x7 surface, core-level photoemission data reveal a strong interaction of the gold with the underlying silicon despite the presence of a chemisorbed fullerene monolayer. The Si 2p PES data exhibit dramatic changes consistent with the formation of a gold silicide, which is also evident from the corresponding Au 4f spectra. Valence band photoemission also reveals the absence of appreciable density of states at the Fermi level following the adsorption of either metal, indicating a negligible transfer of electrons from the adsorbed metal to the C 60 cage

  10. Comparison between the classical interaction energy and periodic Hartree-Fock binding energies for the interaction between molecules and surfaces

    International Nuclear Information System (INIS)

    Chacon-Taylor, M.R.; McCarthy, M.I.

    1995-01-01

    The energetics of the H 2 O/MgO(001), HCl/MgO(001), and NH 3 /MgO(001) interface were investigated using the ab initio periodic Hartree-Fock LCAO method and a classical interaction energy model. The QM calculations treated a system that was periodic in two dimensions with the adsorbate approaching a three-layer slab of MgO(001). The authors used an approximation to the classical interaction energy, where the surface is represented by its potential, electric field, and electric field derivatives at the positions of the molecule center of mass, and the molecule is described by its charge, electric dipole, electric quadrupole and polarizability. The potential, electric field and electric field gradient are obtained for the clean three-layer slab using the ab initio periodic Hartree-Fock LCAO method (CRYSTAL) and an optimized split valence basis 8-61G on Mg and 8-51G on O. The charge, electric dipole, and electric quadrupole are calculated using ab initio Hartree-Fock theory (GAUSSIAN-92) with a 6-31G* basis set while the SCF polarizability is determined analytically using the same basis set

  11. Investigating the effect of surface water - groundwater interactions on stream temperature using Distributed temperature sensing and instream temperature model

    DEFF Research Database (Denmark)

    Karthikeyan, Matheswaran; Blemmer, Morten; Mortensen, Julie Flor

    2011-01-01

    Surface water–groundwater interactions at the stream interface influences, and at times controls the stream temperature, a critical water property driving biogeochemical processes. This study investigates the effects of these interactions on temperature of Stream Elverdamsåen in Denmark using...... the Distributed Temperature Sensing (DTS) system and instream temperature modelling. Locations of surface water–groundwater interactions were identified from the temperature data collected over a 2-km stream reach using a DTS system with 1-m spatial and 5-min temporal resolution. The stream under consideration...... surface water–groundwater interactions on heterogeneous behaviour of stream temperature....

  12. An Empirical Jet-Surface Interaction Noise Model with Temperature and Nozzle Aspect Ratio Effects

    Science.gov (United States)

    Brown, Cliff

    2015-01-01

    An empirical model for jet-surface interaction (JSI) noise produced by a round jet near a flat plate is described and the resulting model evaluated. The model covers unheated and hot jet conditions (1 less than or equal to jet total temperature ratio less than or equal to 2.7) in the subsonic range (0.5 less than or equal to M(sub a) less than or equal to 0.9), surface lengths 0.6 less than or equal to (axial distance from jet exit to surface trailing edge (inches)/nozzle exit diameter) less than or equal to 10, and surface standoff distances (0 less than or equal to (radial distance from jet lipline to surface (inches)/axial distance from jet exit to surface trailing edge (inches)) less than or equal to 1) using only second-order polynomials to provide predictable behavior. The JSI noise model is combined with an existing jet mixing noise model to produce exhaust noise predictions. Fit quality metrics and comparisons to between the predicted and experimental data indicate that the model is suitable for many system level studies. A first-order correction to the JSI source model that accounts for the effect of nozzle aspect ratio is also explored. This correction is based on changes to the potential core length and frequency scaling associated with rectangular nozzles up to 8:1 aspect ratio. However, more work is needed to refine these findings into a formal model.

  13. The Interaction of a Turbulent Ship-Hull Boundary Layer and a Free Surface

    Science.gov (United States)

    Masnadi, N.; Washuta, N.; Wang, A.; Duncan, J. H.

    2013-11-01

    The free-surface deformation pattern caused by subsurface turbulent velocity fluctuations in the boundary layer at the mid-length of a naval ship is studied with a novel laboratory scale experimental technique. In this technique, the boundary layer is created in a large tank (13.4 m long, 1.3 m tall, and 2.4 m wide) with a surface-piercing meter-wide stainless steel belt that travels in a horizontal loop around two vertically oriented rollers whose axes are separated by 7.5 m. The device is enclosed in a dry box except for one of the two lengths between the rollers where a straight 6-meter-long section is exposed to the water and represents one side of the ship hull. The belt operates at full-scale ship speeds (up to 15 m/s) in order to match the Reynolds, Froude, and Weber numbers to those of naval ships, thus faithfully modeling the interaction of the turbulence with the free surface at laboratory scale. The water surface profile history midway between the rollers is recorded cinematically in a vertical plane normal to the belt using a Laser Induced Fluorescence (LIF) technique. This surface profile data is used to study the near-wall and far-field frequency content and propagation behavior of the surface ripples. The support of the Office of Naval Research is gratefully acknowledged.

  14. Early interactions between leukocytes and three different potentially bioactive titanium surface modifications.

    Science.gov (United States)

    Arvidsson, Anna; Malmberg, Per; Kjellin, Per; Currie, Fredrik; Arvidsson, Martin; Franke Stenport, Victoria

    2011-05-01

    The aim of the present study was to compare the early interactions between leukocytes and three different surface modifications, suggested as bioactive. Blasted titanium discs were modified by alkali and heat treatment, sodium fluoride treatment, or hydroxyapatite coating. A number of these discs were also immersed in simulated body fluid (SBF) for a week, a treatment which yielded high levels of calcium and phosphate on each surface type. The specimens were exposed for human venous blood for 32 minutes and the respiratory burst response was measured in terms of reactive oxygen species with a luminometer, and coverage of viable cells with a fluorescence microscope after staining steps. The topography, morphology, and chemistry of the surfaces were evaluated with optical interferometry and scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX). A high respiratory burst response was found for HA coated titanium in comparison with the other surface groups (p burst response (p < 0.0005) and removed statistically significant differences between the surface groups. Thus, the results in the present study indicate that different titanium surface modifications influence the early inflammatory response differently, and that calcium phosphate compounds increase the inflammatory response. Copyright © 2011 Wiley Periodicals, Inc.

  15. Colloid transport with wetting fronts: interactive effects of solution surface tension and ionic strength.

    Science.gov (United States)

    Zhuang, Jie; Goeppert, Nadine; Tu, Ching; McCarthy, John; Perfect, Edmund; McKay, Larry

    2010-02-01

    Transport of colloids with transient wetting fronts represents an important mechanism of contaminant migration in the vadose zone. The work presented here used steady-state saturated and transient unsaturated flow columns to evaluate the transport of a fluorescent latex microsphere (980 nm in diameter) with capillary wetting fronts of different solution surface tensions and ionic strengths. The saturated transport experiments demonstrated that decreasing solution surface tension and ionic strength decreased colloid deposition at the solid-liquid interface and increased colloid recovery in the column effluent. The effect of solution surface tension on colloid transport and deposition was greater at lower ionic strength, suggesting an interaction between these two factors. Under transient unsaturated flow conditions, the number of colloids retained in sand decreased exponentially with travel distance through the porous media. However, lowering the solution surface tension and ionic strength resulted in a more even distribution of colloids along the column. The measured zeta potentials of colloids in different solutions suggest that both lowering surface tension and ionic strength would enhance the electrostatic repulsion between colloid and sand. The experimental results revealed that the effects are nonlinear, implying the possible existence of critical threshold values, beyond which the effects were not significant. In addition, colloid migration slowed down as solution surface tension decreased due to reduction of capillary forces that drove liquid movement. Copyright 2009 Elsevier Ltd. All rights reserved.

  16. Passive control of flow structure interaction between a sphere and free-surface

    Directory of Open Access Journals (Sweden)

    Akilli Huseyin

    2012-04-01

    Full Text Available Flow characteristics for both a smooth and a vented sphere such as velocity vectors, patterns of streamlines, vorticity contours, stream-wise fluctuations, cross-stream velocity fluctuations and Reynolds stress correlations between a sphere and free-surface for various submerged ratio at Re =5,000 are studied by using dye visualization and the particle image velocimetry technique. Passive control of flow structure interaction between sphere and free surface was examined by using a modified geometry which has a 15% sphere diameter hole passing through the sphere equator. Both of the spheres were separately placed beneath the free surface with different positions from touching to the free surface to two sphere diameters below the free surface. It is demonstrated that reattachment point of the separated flow to the free surface varies for both of the sphere cases as the sphere position alters vertically through the water flow while the flow structure for the vented sphere occurs considerably symmetrical due to forming of a pair of counter-rotating ring vortices.

  17. Effective Electrostatic Interactions Between Two Overall Neutral Surfaces with Quenched Charge Heterogeneity Over Atomic Length Scale

    Science.gov (United States)

    Zhou, S.

    2017-12-01

    the salt ion; whereas if the 1:1 type electrolyte and the symmetrical patterns are considered, then the opposite may be the case. All of these findings can be explained self-consistently from several perspectives: an excess adsorption of the salt ions (induced by the surface charge separation) serving to raise the osmotic pressure between the plates, configuration fine-tuning in the thinner ion adsorption layer driven by the energy decrease principle, direct Coulombic interactions operating between charged objects on the two face-to-face plates involved, and net charge strength in the ion adsorption layer responsible for the net electrostatic repulsion.

  18. Nonlinear response surface in the study of interaction analysis of three combination drugs.

    Science.gov (United States)

    Wan, Wen; Pei, Xin-Yan; Grant, Steven; Birch, Jeffrey B; Felthousen, Jessica; Dai, Yun; Fang, Hong-Bin; Tan, Ming; Sun, Shumei

    2017-01-01

    Few articles have been written on analyzing three-way interactions between drugs. It may seem to be quite straightforward to extend a statistical method from two-drugs to three-drugs. However, there may exist more complex nonlinear response surface of the interaction index (II) with more complex local synergy and/or local antagonism interspersed in different regions of drug combinations in a three-drug study, compared in a two-drug study. In addition, it is not possible to obtain a four-dimensional (4D) response surface plot for a three-drug study. We propose an analysis procedure to construct the dose combination regions of interest (say, the synergistic areas with II≤0.9). First, use the model robust regression method (MRR), a semiparametric method, to fit the entire response surface of the II, which allows to fit a complex response surface with local synergy/antagonism. Second, we run a modified genetic algorithm (MGA), a stochastic optimization method, many times with different random seeds, to allow to collect as many feasible points as possible that satisfy the estimated values of II≤0.9. Last, all these feasible points are used to construct the approximate dose regions of interest in a 3D. A case study with three anti-cancer drugs in an in vitro experiment is employed to illustrate how to find the dose regions of interest. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Time-Domain Modeling of RF Antennas and Plasma-Surface Interactions

    Directory of Open Access Journals (Sweden)

    Jenkins Thomas G.

    2017-01-01

    Full Text Available Recent advances in finite-difference time-domain (FDTD modeling techniques allow plasma-surface interactions such as sheath formation and sputtering to be modeled concurrently with the physics of antenna near- and far-field behavior and ICRF power flow. Although typical sheath length scales (micrometers are much smaller than the wavelengths of fast (tens of cm and slow (millimeter waves excited by the antenna, sheath behavior near plasma-facing antenna components can be represented by a sub-grid kinetic sheath boundary condition, from which RF-rectified sheath potential variation over the surface is computed as a function of current flow and local plasma parameters near the wall. These local time-varying sheath potentials can then be used, in tandem with particle-in-cell (PIC models of the edge plasma, to study sputtering effects. Particle strike energies at the wall can be computed more accurately, consistent with their passage through the known potential of the sheath, such that correspondingly increased accuracy of sputtering yields and heat/particle fluxes to antenna surfaces is obtained. The new simulation capabilities enable time-domain modeling of plasma-surface interactions and ICRF physics in realistic experimental configurations at unprecedented spatial resolution. We will present results/animations from high-performance (10k-100k core FDTD/PIC simulations of Alcator C-Mod antenna operation.

  20. Mathematical modelling of surface water-groundwater flow and salinity interactions in the coastal zone

    Science.gov (United States)

    Spanoudaki, Katerina; Kampanis, Nikolaos A.

    2014-05-01

    Coastal areas are the most densely-populated areas in the world. Consequently water demand is high, posing great pressure on fresh water resources. Climatic change and its direct impacts on meteorological variables (e.g. precipitation) and indirect impact on sea level rise, as well as anthropogenic pressures (e.g. groundwater abstraction), are strong drivers causing groundwater salinisation and subsequently affecting coastal wetlands salinity with adverse effects on the corresponding ecosystems. Coastal zones are a difficult hydrologic environment to represent with a mathematical model due to the large number of contributing hydrologic processes and variable-density flow conditions. Simulation of sea level rise and tidal effects on aquifer salinisation and accurate prediction of interactions between coastal waters, groundwater and neighbouring wetlands requires the use of integrated surface water-groundwater models. In the past few decades several computer codes have been developed to simulate coupled surface and groundwater flow. In these numerical models surface water flow is usually described by the 1-D Saint Venant equations (e.g. Swain and Wexler, 1996) or the 2D shallow water equations (e.g. Liang et al., 2007). Further simplified equations, such as the diffusion and kinematic wave approximations to the Saint Venant equations, are also employed for the description of 2D overland flow and 1D stream flow (e.g. Gunduz and Aral, 2005). However, for coastal bays, estuaries and wetlands it is often desirable to solve the 3D shallow water equations to simulate surface water flow. This is the case e.g. for wind-driven flows or density-stratified flows. Furthermore, most integrated models are based on the assumption of constant fluid density and therefore their applicability to coastal regions is questionable. Thus, most of the existing codes are not well-suited to represent surface water-groundwater interactions in coastal areas. To this end, the 3D integrated

  1. Compressible or incompressible blend of interacting monodisperse star and linear polymers near a surface.

    Science.gov (United States)

    Batman, Richard; Gujrati, P D

    2008-03-28

    We consider a lattice model of a mixture of repulsive, attractive, or neutral monodisperse star (species A) and linear (species B) polymers with a third monomeric species C, which may represent free volume. The mixture is next to a hard, infinite plate whose interactions with A and C can be attractive, repulsive, or neutral. These two interactions are the only parameters necessary to specify the effect of the surface on all three components. We numerically study monomer density profiles using the method of Gujrati and Chhajer that has already been previously applied to study polydisperse and monodisperse linear-linear blends next to surfaces. The resulting density profiles always show an enrichment of linear polymers in the immediate vicinity of the surface due to entropic repulsion of the star core. However, the integrated surface excess of star monomers is sometimes positive, indicating an overall enrichment of stars. This excess increases with the number of star arms only up to a certain critical number and decreases thereafter. The critical arm number increases with compressibility (bulk concentration of C). The method of Gujrati and Chhajer is computationally ultrafast and can be carried out on a personal computer (PC), even in the incompressible case, when simulations are unfeasible. Calculations of density profiles usually take less than 20 min on PCs.

  2. Magnetic Interaction between Surface-Engineered Rare-Earth Atomic Spins

    Directory of Open Access Journals (Sweden)

    Chiung-Yuan Lin

    2012-06-01

    Full Text Available We report the ab-initio study of rare-earth adatoms (Gd on an insulating surface. This surface is of interest because of previous studies by scanning tunneling microscopy showing spin excitations of transition-metal adatoms. The present work is the first study of rare-earth spin-coupled adatoms, as well as the geometry effect of spin coupling and the underlying mechanism of ferromagnetic coupling. The exchange coupling between Gd atoms on the surface is calculated to be antiferromagnetic in a linear geometry and ferromagnetic in a diagonal geometry. We also find that the Gd dimers in these two geometries are similar to the nearest-neighbor and the next-nearest-neighbor Gd atoms in GdN bulk. We analyze how much direct exchange, superexchange, and Ruderman-Kittel-Kasuya-Yosida interactions contribute to the exchange coupling for both geometries by additional first-principles calculations of related model systems.

  3. Analyses of Interactions Between Heparin and the Apical Surface Proteins of Plasmodium falciparum

    Science.gov (United States)

    Kobayashi, Kyousuke; Takano, Ryo; Takemae, Hitoshi; Sugi, Tatsuki; Ishiwa, Akiko; Gong, Haiyan; Recuenco, Frances C.; Iwanaga, Tatsuya; Horimoto, Taisuke; Akashi, Hiroomi; Kato, Kentaro

    2013-11-01

    Heparin, a sulfated glycoconjugate, reportedly inhibits the blood-stage growth of the malaria parasite Plasmodium falciparum. Elucidation of the inhibitory mechanism is valuable for developing novel invasion-blocking treatments based on heparin. Merozoite surface protein 1 has been reported as a candidate target of heparin; however, to better understand the molecular mechanisms involved, we characterized the molecules that bind to heparin during merozoite invasion. Here, we show that heparin binds only at the apical tip of the merozoite surface and that multiple heparin-binding proteins localize preferentially in the apical organelles. To identify heparin-binding proteins, parasite proteins were fractionated by means of heparin affinity chromatography and subjected to immunoblot analysis with ligand-specific antibodies. All tested members of the Duffy and reticulocyte binding-like families bound to heparin with diverse affinities. These findings suggest that heparin masks the apical surface of merozoites and blocks interaction with the erythrocyte membrane after initial attachment.

  4. Towards hot electron mediated charge exchange in hyperthermal energy ion-surface interactions

    DEFF Research Database (Denmark)

    Ray, M. P.; Lake, R. E.; Thomsen, Lasse Bjørchmar

    2010-01-01

    electrons useful for driving chemical reactions at surfaces. Using the binary collision approximation and a nonadiabatic model that takes into account the time-varying nature of the ion–surface interaction, the energy loss of the ions is reproduced. The energy loss for Na + ions incident on the devices......We have made Na + and He + ions incident on the surface of solid state tunnel junctions and measured the energy loss due to atomic displacement and electronic excitations. Each tunnel junction consists of an ultrathin film metal–oxide–semiconductor device which can be biased to create a band of hot...... shows that the primary energy loss mechanism is the atomic displacement of Au atoms in the thin film of the metal–oxide–semiconductor device. We propose that neutral particle detection of the scattered flux from a biased device could be a route to hot electron mediated charge exchange....

  5. Modelling free surface aquifers to analyze the interaction between groundwater and sinuous streams

    DEFF Research Database (Denmark)

    Balbarini, Nicola; Boon, W. M.; Bjerg, Poul Løgstrup

    and errors. In addition, when streams are sinuous, groundwater flow is truly 3-dimensional, with strong vertical flows and sharp changes in horizontal direction. Here 3 different approaches to simulating free surface aquifers are compared for simulating groundwater-stream interaction. The aim of the models......: a saturated-unsaturated flow model, moving mesh, and a new coordinate transformation. The saturated/unsaturated model couples the saturated groundwater flow equation with a solution of Richards equation. The moving mesh solves the saturated groundwater equation with a free surface and deformable numerical...... finite element mesh. Finally, the new coordinate transform method employs a coordinate transform so that the saturated groundwater flow equation is solved on a fixed finite element mesh with a stationary free surface. This paper describes in detail the new coordinate transform method. It employs...

  6. Surface water and groundwater interaction in selected areas of Indus basin

    International Nuclear Information System (INIS)

    Akram, W.; Ahmad, M.; Tariq, J.A.; Latif, Z.; Malik, M.R.

    2011-08-01

    Isotope hydrological investigations were carried out in Marala-Khanki Area of Punjab for elucidating various aspects of surface water and groundwater interaction. Groundwater samples were collected on seasonal basis (low and high river discharge periods) while surface water (Chenab River) samples were collected more frequently (weekly or monthly basis). Isotopic data suggested that there is no significant contribution of surface water to groundwater recharge in Marala-Khanki Area and rain is the prevailing source of groundwater recharge. The data further revealed that isotopic values of Tarbala lake are higher than those of main lake. Indus river meaning that there is significant contribution of base flow in this pocket. Isotopic data of Indus river showed an increase at Tunsa as compared to Chashma in flow period indicating the high contribution of base flow at this point in time. Stable isotopes were successfully used to quantify the base flow contribution. (author)

  7. Studying cell-surface interactions in vitro: a survey of experimental approaches and techniques.

    Science.gov (United States)

    Michaelis, Stefanie; Robelek, Rudolf; Wegener, Joachim

    2012-01-01

    A better understanding of the interactions of animal (or human) cells with in vitro surfaces is the key to the successful development, improvement and optimization of biomaterials for biomedical or biotechnological purposes. State-of-the-art experimental approaches and techniques are a prerequisite for further and deeper insights into the mechanisms and processes involved in cell-surface adhesion. This chapter provides a brief but not complete survey of optical, mechanical, electrochemical and acoustic devices that are currently used to study the structural and functional properties of the cell-surface junction. Each technique is introduced with respect to the underlying principles before example data are discussed. At the end of the chapter all techniques are compared in terms of their strengths, limitations and technical requirements.

  8. Dynamics of Plasma-Surface Interactions using In-situ Ion Beam Analysis

    International Nuclear Information System (INIS)

    Whyte, D.G.

    2009-01-01

    The overall goal of this proposal was to develop an innovative experimental facility that would allow for the measurement of real-time response of a material surface to plasma bombardment by employing in-situ high-energy ion beam analysis. This facility was successfully developed and deployed at U. Wisconsin-Madison and was named DIONISOS (Dynamics of IONic Implantation and Sputtering on Surfaces). There were several major highlights to the DIONISOS research which we will briefly highlight below. The full technical details of the DIONISOS development, deployment and research results are contained in the Appendices which contain several peer-reviewed publications and a PhD thesis devoted to DIONISOS. The DIONISOS results on deuterium retention in molybdenum were chosen as an invited talk at the 2008 International Conference on Plasma-Surface Interactions in Toledo, Spain.

  9. Interaction between carbon fibers and polymer sizing: Influence of fiber surface chemistry and sizing reactivity

    Science.gov (United States)

    Moosburger-Will, Judith; Bauer, Matthias; Laukmanis, Eva; Horny, Robert; Wetjen, Denise; Manske, Tamara; Schmidt-Stein, Felix; Töpker, Jochen; Horn, Siegfried

    2018-05-01

    Different aspects of the interaction of carbon fibers and epoxy-based polymer sizings are investigated, e.g. the wetting behavior, the strength of adhesion between fiber and sizing, and the thermal stability of the sizing layer. The influence of carbon fiber surface chemistry and sizing reactivity is investigated using fibers of different degree of anodic oxidation and sizings with different number of reactive epoxy groups per molecule. Wetting of the carbon fibers by the sizing dispersion is found to be specified by both, the degree of fiber activation and the sizing reactivity. In contrast, adhesion strength between fibers and sizing is dominated by the surface chemistry of the carbon fibers. Here, the number of surface oxygen groups seems to be the limiting factor. We also find that the sizing and the additional functionalities induced by anodic oxidation are removed by thermal treatment at 600 °C, leaving the carbon fiber in its original state after carbonization.

  10. Selectivity by Small-Molecule Inhibitors of Protein Interactions Can Be Driven by Protein Surface Fluctuations

    Science.gov (United States)

    Johnson, David K.; Karanicolas, John

    2015-01-01

    Small-molecules that inhibit interactions between specific pairs of proteins have long represented a promising avenue for therapeutic intervention in a variety of settings. Structural studies have shown that in many cases, the inhibitor-bound protein adopts a conformation that is distinct from its unbound and its protein-bound conformations. This plasticity of the protein surface presents a major challenge in predicting which members of a protein family will be inhibited by a given ligand. Here, we use biased simulations of Bcl-2-family proteins to generate ensembles of low-energy conformations that contain surface pockets suitable for small molecule binding. We find that the resulting conformational ensembles include surface pockets that mimic those observed in inhibitor-bound crystal structures. Next, we find that the ensembles generated using different members of this protein family are overlapping but distinct, and that the activity of a given compound against a particular family member (ligand selectivity) can be predicted from whether the corresponding ensemble samples a complementary surface pocket. Finally, we find that each ensemble includes certain surface pockets that are not shared by any other family member: while no inhibitors have yet been identified to take advantage of these pockets, we expect that chemical scaffolds complementing these “distinct” pockets will prove highly selective for their targets. The opportunity to achieve target selectivity within a protein family by exploiting differences in surface fluctuations represents a new paradigm that may facilitate design of family-selective small-molecule inhibitors of protein-protein interactions. PMID:25706586

  11. Modeling Groundwater-Surface Water Interaction and Contaminant Transport of Chlorinated Solvent Contaminated Site

    Science.gov (United States)

    Yimer Ebrahim, Girma; Jonoski, Andreja; van Griensven, Ann; Dujardin, Juliette; Baetelaan, Okke; Bronders, Jan

    2010-05-01

    Chlorinated-solvent form one of the largest groups of environmental chemicals. Their use and misuse in industry have lead to a large entry of these chemicals into the environment, resulting in widespread dissemination and oftentimes environmental contamination. Chlorinated solvent contamination of groundwater resources has been widely reported. For instance, there has been much interest in the assessment of these contaminant levels and their evolutions with time in the groundwater body below the Vilvoorde-Machelen industrial area (Belgium). The long industrial history of the area has lead to complex patterns of pollution from multiple sources and the site has been polluted to the extent that individual plumes are not definable any more. Understanding of groundwater/surface water interaction is a critical component for determining the fate of contaminant both in streams and ground water due to the fact that groundwater and surface water are in continuous dynamic interaction in the hydrologic cycle. The interaction has practical consequences in the quantity and quality of water in either system in the sense that depletion and/or contamination of one of the system will eventually affect the other one. The transition zone between a stream and its adjacent aquifer referred to as the hyporheic zone plays a critical role in governing contaminant exchange and transformation during water exchange between the two water bodies. The hyporheic zone of Zenne River ( the main receptor ) is further complicated due to the fact that the river banks are artificially trained with sheet piles along its reach extending some 12 m below the surface. This study demonstrates the use of MODFLOW, a widely used modular three-dimensional block-centred finite difference, saturated flow model for simulating the flow and direction of movement of groundwater through aquifer and stream-aquifer interaction and the use of transport model RT3D, a three-dimensional multi-species reactive transport model

  12. Seasonal Influences on Ground-Surface Water Interactions in an Arsenic-Affected Aquifer in Cambodia

    Science.gov (United States)

    Richards, L. A.; Magnone, D.; Van Dongen, B.; Bryant, C.; Boyce, A.; Ballentine, C. J.; Polya, D. A.

    2015-12-01

    Millions of people in South and Southeast Asia consume drinking water daily which contains dangerous levels of arsenic exceeding health-based recommendations [1]. A key control on arsenic mobilization in aquifers in these areas has been controversially identified as the interaction of 'labile' organic matter contained in surface waters with groundwaters and sediments at depth [2-4], which may trigger the release of arsenic from the solid- to aqueous-phase via reductive dissolution of iron-(hyr)oxide minerals [5]. In a field site in Kandal Province, Cambodia, which is an arsenic-affected area typical to others in the region, there are strong seasonal patterns in groundwater flow direction, which are closely related to monsoonal rains [6] and may contribute to arsenic release in this aquifer. The aim of this study is to explore the implications of the high susceptibility of this aquifer system to seasonal changes on potential ground-surface water interactions. The main objectives are to (i) identify key zones where there are likely ground-surface water interactions, (ii) assess the seasonal impact of such interactions and (iii) quantify the influence of interactions using geochemical parameters (such as As, Fe, NO3, NH4, 14C, 3T/3He, δ18O, δ2H). Identifying the zones, magnitude and seasonal influence of ground-surface water interactions elucidates new information regarding potential locations/pathways of arsenic mobilization and/or transport in affected aquifers and may be important for water management strategies in affected areas. This research is supported by NERC (NE/J023833/1) to DP, BvD and CJB and a NERC PhD studentship (NE/L501591/1) to DM. References: [1] World Health Organization, 2008. [2] Charlet & Polya (2006), Elements, 2, 91-96. [3] Harvey et al. (2002), Science, 298, 1602-1606. [4] Lawson et al. (2013), Env. Sci. Technol. 47, 7085 - 7094. [5] Islam et al. (2004), Nature, 430, 68-71. [6] Benner et al. (2008) Appl. Geochem. 23(11), 3072 - 3087.

  13. Observations of flow path interactions with surface structures during initial soil development stage using irrigation experiments

    Science.gov (United States)

    Bartl, Steffen; Biemelt, Detlef; Badorreck, Annika; Gerke, Horst H.

    2010-05-01

    Structures and processes are dynamically linked especially during initial stages of soil and ecosystem development. Here we assume that soil pore structures and micro topography determine the flow paths and water fluxes as well as further structure changes. Reports about flow path developments at the soil surface are still limited because of an insufficient knowledge of the changing micro topography at the surface. The objective of this presentation is to evaluate methods for parameterisation of surface micro topography for analysing interactions between infiltration and surface runoff. Complex irrigation experiments were carried out at an experimental site in the neighbourhood of the artificially created water catchment "Chicken Creek". The irrigation rates between 160 mm/h and 250 mm/h were held constant over a time period of 20 minutes. The incoming intensities were measured as well as the raindrop-velocity and -size distributions. The surface runoff was continuously registered, soil samples were taken, and soil water potential heads were monitored using tensiometers. Surface and subsurface flow paths were identified using different tracers. The soil surface structures were recorded using a high resolution digital camera before, during, and after irrigation. Micro topography was surveyed using close-range photogrammetry. With this experimental design both, flow paths on the surface and in the soil as well as structure and texture changes could be observed simultaneously. In 2D vertical cross-sections, the effect of initial sediment deposition structure on infiltration and runoff was observed. Image analysis of surface pictures allowed identifying structural and soil textural changes during the runoff process. Similar structural changes related to surface flow paths were found with the photogrammetric surface analysis. We found evidence for the importance of the initial structures on the flow paths as well as a significant influence of the system development

  14. Fabrication Localized Surface Plasmon Resonance sensor chip of gold nanoparticles and detection lipase–osmolytes interaction

    Energy Technology Data Exchange (ETDEWEB)

    Ghodselahi, T., E-mail: t_ghodselahi@yahoo.com [Nano Mabna Iranian Inc., PO Box 1676664116, Tehran (Iran, Islamic Republic of); School of Physics, Institute for Research in Fundamental Sciences, PO Box 19395-5531, Tehran (Iran, Islamic Republic of); Hoornam, S. [Nano Mabna Iranian Inc., PO Box 1676664116, Tehran (Iran, Islamic Republic of); School of Physics, Institute for Research in Fundamental Sciences, PO Box 19395-5531, Tehran (Iran, Islamic Republic of); Department of Science, Central Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Vesaghi, M.A. [Department of Physics, Sharif University of Technology, PO Box 11365-9161, Tehran (Iran, Islamic Republic of); Ranjbar, B.; Azizi, A. [Department of Biophysics, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Mobasheri, H. [Laboratory of Membrane Biophysics, Institute of Biochemistry and Biophysics, University of Tehran, PO Box 13145-1384, Tehran (Iran, Islamic Republic of); Biomaterials Research Institute (BRC), University of Tehran, Tehran (Iran, Islamic Republic of)

    2014-09-30

    Highlights: • We synthesized localized surface plasmon resonance sensor of gold nanoparticles by RF-sputtering and RF-PECVD. • LSPR sensor was characterized by TEM, XPS, AFM. • LSPR sensor was utilized to detect interaction between sorbitol and trehalose, with Pesudomonace Cepacia Lipase (PCL). • Unlike to trehalose, sorbitol interacts with the PCL. • Refractive index of PCL was obtained by Mie theory modeling. - Abstract: Co-deposition of RF-sputtering and RF-PECVD from acetylene gas and Au target were used to prepare sensor chip of gold nanoparticles (Au NPs). Deposition conditions were optimized to reach a Localized Surface Plasmon Resonance (LSPR) sensor chip of Au NPs with particle size less than 10 nm. The RF power was set at 180 W and the initial gas pressure was set at 0.035 mbar. Transmission Electron Microscopy (TEM) images and Atomic Force Microscopy (AFM) data were used to investigate particles size and surface morphology of LSPR sensor chip. The Au and C content of the LSPR sensor chip of Au NPs was obtained from X-ray photoelectron spectroscopy (XPS). The hydrogenated amorphous carbon (a-C:H) thin film was used as intermediate material to immobilize Au NPs on the SiO{sub 2} substrate. The interaction between two types of osmolytes, i.e. sorbitol and trehalose, with Pseudomonas cepacia lipase (PCL) were detected by the prepared LSPR biosensor chip. The detection mechanism is based on LSPR spectroscopy in which the wavelength of absorption peak is sensitive to the refractive index of the environment of the Au NPs. This mechanism eliminates the use of a probe or immobilization of PCL on the Au NPs of LSPR sensor chip. The interaction between PCL and osmolytes can change refractive index of the mixture or solution. We found that unlike to trehalose, sorbitol interacts with the PCL. This interaction increases refractive index of the PCL and sorbitol mixture. Refractive index of PCL in the presence of different concentration of sorbitol was

  15. Theory of synergistic effects: Hill-type response surfaces as 'null-interaction' models for mixtures.

    Science.gov (United States)

    Schindler, Michael

    2017-08-02

    The classification of effects caused by mixtures of agents as synergistic, antagonistic or additive depends critically on the reference model of 'null interaction'. Two main approaches are currently in use, the Additive Dose (ADM) or concentration addition (CA) and the Multiplicative Survival (MSM) or independent action (IA) models. We compare several response surface models to a newly developed Hill response surface, obtained by solving a logistic partial differential equation (PDE). Assuming that a mixture of chemicals with individual Hill-type dose-response curves can be described by an n-dimensional logistic function, Hill's differential equation for pure agents is replaced by a PDE for mixtures whose solution provides Hill surfaces as 'null-interaction' models and relies neither on Bliss independence or Loewe additivity nor uses Chou's unified general theory. An n-dimensional logistic PDE decribing the Hill-type response of n-component mixtures is solved. Appropriate boundary conditions ensure the correct asymptotic behaviour. Mathematica 11 (Wolfram, Mathematica Version 11.0, 2016) is used for the mathematics and graphics presented in this article. The Hill response surface ansatz can be applied to mixtures of compounds with arbitrary Hill parameters. Restrictions which are required when deriving analytical expressions for response surfaces from other principles, are unnecessary. Many approaches based on Loewe additivity turn out be special cases of the Hill approach whose increased flexibility permits a better description of 'null-effect' responses. Missing sham-compliance of Bliss IA, known as Colby's model in agrochemistry, leads to incompatibility with the Hill surface ansatz. Examples of binary and ternary mixtures illustrate the differences between the approaches. For Hill-slopes close to one and doses below the half-maximum effect doses MSM (Colby, Bliss, Finney, Abbott) predicts synergistic effects where the Hill model indicates 'null-interaction

  16. Modeling multivalent ligand-receptor interactions with steric constraints on configurations of cell surface receptor aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Monine, Michael [Los Alamos National Laboratory; Posner, Richard [TRANSLATION GENOMICS RESAEARCH INSTITUTE; Savage, Paul [BYU; Faeder, James [UNIV OF PITTSBURGH; Hlavacek, William S [UNM

    2008-01-01

    Signal transduction generally involves multivalent protein-protein interactions, which can produce various protein complexes and post-translational modifications. The reaction networks that characterize these interactions tend to be so large as to challenge conventional simulation procedures. To address this challenge, a kinetic Monte Carlo (KMC) method has been developed that can take advantage of a model specification in terms of reaction rules for molecular interactions. A set of rules implicitly defines the reactions that can occur as a result of the interactions represented by the rules. With the rule-based KMC method, explicit generation of the underlying chemical reaction network implied by rules is avoided. Here, we apply and extend this method to characterize the interactions of a trivalent ligand with a bivalent cell-surface receptor. This system is also studied experimentally. We consider the following kinetic models: an equivalent-site model, an extension of this model, which takes into account steric constraints on the configurations of receptor aggregates, and finally, a model that accounts for cyclic receptor aggregates. Simulation results for the equivalent-site model are consistent with an equilibrium continuum model. Using these models, we investigate the effects of steric constraints and the formation of cyclic aggregates on the kinetics and equilibria of small and large aggregate formation and the percolation phase transition that occurs in this system.

  17. Modeling of peptide adsorption interactions with a poly(lactic acid) surface.

    Science.gov (United States)

    O'Brien, C P; Stuart, S J; Bruce, D A; Latour, R A

    2008-12-16

    The biocompatibility of implanted materials and devices is governed by the conformation, orientation, and composition of the layer of proteins that adsorb to the surface of the material immediately upon implantation, so an understanding of this adsorbed protein layer is essential to the rigorous and methodical design of implant materials. In this study, novel molecular dynamics techniques were employed in order to determine the change in free energy for the adsorption of a solvated nine-residue peptide (GGGG-K-GGGG) to a crystalline polylactide surface in an effort to elucidate the fundamental mechanisms that govern protein adsorption. This system, like many others, involves two distinct types of sampling problems: a spatial sampling problem, which arises due to entropic effects creating barriers in the free energy profile, and a conformational sampling problem, which occurs due to barriers in the potential energy landscape. In a two-step process that addresses each sampling problem in turn, the technique of biased replica exchange molecular dynamics was refined and applied in order to overcome these sampling problems and, using the information available at the atomic level of detail afforded by molecular simulation, both quantify and characterize the interactions between the peptide and a relevant biomaterial surface. The results from these simulations predict a fairly strong adsorption response with an adsorption free energy of -2.5 +/- 0.6 kcal/mol (mean +/- 95% confidence interval), with adsorption primarily due to hydrophobic interactions between the nonpolar groups of the peptide and the PLA surface. As part of a larger and ongoing effort involving both simulation and experimental investigations, this work contributes to the goal of transforming the engineering of biomaterials from one dominated by trial-and-error to one which is guided by an atomic-level understanding of the interactions that occur at the tissue-biomaterial interface.

  18. Interactions on External MOF Surfaces: Desorption of Water and Ethanol from CuBDC Nanosheets.

    Science.gov (United States)

    Elder, Alexander C; Aleksandrov, Alexandr B; Nair, Sankar; Orlando, Thomas M

    2017-10-03

    The external surfaces of metal-organic framework (MOF) materials are difficult to experimentally isolate due to the high porosities of these materials. MOF surface surrogates in the form of copper benzenedicarboxylate (CuBDC) nanosheets were synthesized using a bottom-up approach, and the surface interactions of water and ethanol were investigated by temperature-programmed desorption (TPD). A method of analysis of diffusion-influenced TPD was developed to measure the desorption properties of these porous materials. This approach also allows the extraction of diffusion coefficients from TPD data. The transmission Fourier transform infrared spectra, powder X-ray diffraction patterns, and TPD data indicate that water desorbs from CuBDC nanosheets with activation energies of 44 ± 2 kJ/mol at edge sites and 58 ± 1 kJ/mol at external surface and internal and pore sites. Ethanol desorbs with activation energies of 58 ± 1 kJ/mol at internal pore sites and 66 ± 0.4 kJ/mol at external surface sites. Co-adsorption of water and ethanol was also investigated. The presence of ethanol was found to inhibit the desorption of water, resulting in a water desorption process with an activation energy of 68 ± 0.7 kJ/mol.

  19. Study of plasma-surface interaction at the GOL-3 facility

    International Nuclear Information System (INIS)

    Shoshin, A.A.; Arakcheev, A.S.; Arzhannikov, A.V.; Burdakov, A.V.; Ivanov, I.A.; Kasatov, A.A.; Kuklin, K.N.; Polosatkin, S.V.; Postupaev, V.V.; Sinitsky, S.L.

    2017-01-01

    The review presents experimental studies of plasma-surface interaction and materials behavior under plasma loads done in the multiple-mirror trap of the GOL-3 facility. In the experiments for the PSI, the energy density in the extracted plasma stream varies from 0.5 to 30 MJ/m 2 . Parameters of near-surface plasma measured by a set of diagnostics are reviewed. Surface patterns of targets exposed to the plasma are analyzed. The erosion depth depends on the energy loads—it rises from 0 to 600 μm at 0.5 and 30 MJ/m 2 , correspondingly. Cracking and evolution of graphite and tungsten surface morphology are discussed. The enthalpy of brittle destruction of graphite (10 kJ/g), which determines the threshold of bulk damage of targets irradiated with a charged-particle flux with large penetration depth, was determined. Comparison of different facilities for PSI studies are presented. Heat flux play a key role to the target surface erosion.

  20. Remote control of tissue interactions via engineered photo-switchable cell surfaces.

    Science.gov (United States)

    Luo, Wei; Pulsipher, Abigail; Dutta, Debjit; Lamb, Brian M; Yousaf, Muhammad N

    2014-09-10

    We report a general cell surface molecular engineering strategy via liposome fusion delivery to create a dual photo-active and bio-orthogonal cell surface for remote controlled spatial and temporal manipulation of microtissue assembly and disassembly. Cell surface tailoring of chemoselective functional groups was achieved by a liposome fusion delivery method and quantified by flow cytometry and characterized by a new cell surface lipid pull down mass spectrometry strategy. Dynamic co-culture spheroid tissue assembly in solution and co-culture tissue multilayer assembly on materials was demonstrated by an intercellular photo-oxime ligation that could be remotely cleaved and disassembled on demand. Spatial and temporal control of microtissue structures containing multiple cell types was demonstrated by the generation of patterned multilayers for controlling stem cell differentiation. Remote control of cell interactions via cell surface engineering that allows for real-time manipulation of tissue dynamics may provide tools with the scope to answer fundamental questions of cell communication and initiate new biotechnologies ranging from imaging probes to drug delivery vehicles to regenerative medicine, inexpensive bioreactor technology and tissue engineering therapies.

  1. Remote Control of Tissue Interactions via Engineered Photo-switchable Cell Surfaces

    Science.gov (United States)

    Luo, Wei; Pulsipher, Abigail; Dutta, Debjit; Lamb, Brian M.; Yousaf, Muhammad N.

    2014-01-01

    We report a general cell surface molecular engineering strategy via liposome fusion delivery to create a dual photo-active and bio-orthogonal cell surface for remote controlled spatial and temporal manipulation of microtissue assembly and disassembly. Cell surface tailoring of chemoselective functional groups was achieved by a liposome fusion delivery method and quantified by flow cytometry and characterized by a new cell surface lipid pull down mass spectrometry strategy. Dynamic co-culture spheroid tissue assembly in solution and co-culture tissue multilayer assembly on materials was demonstrated by an intercellular photo-oxime ligation that could be remotely cleaved and disassembled on demand. Spatial and temporal control of microtissue structures containing multiple cell types was demonstrated by the generation of patterned multilayers for controlling stem cell differentiation. Remote control of cell interactions via cell surface engineering that allows for real-time manipulation of tissue dynamics may provide tools with the scope to answer fundamental questions of cell communication and initiate new biotechnologies ranging from imaging probes to drug delivery vehicles to regenerative medicine, inexpensive bioreactor technology and tissue engineering therapies. PMID:25204325

  2. FLUID-STRUCTURE INTERACTION IN A U-TUBE WITH SURFACE ROUGHNESS AND PRESSURE DROP

    Directory of Open Access Journals (Sweden)

    GYUN-HO GIM

    2014-10-01

    Full Text Available In this research, the surface roughness affecting the pressure drop in a pipe used as the steam generator of a PWR was studied. Based on the CFD (Computational Fluid Dynamics technique using a commercial code named ANSYS-FLUENT, a straight pipe was modeled to obtain the Darcy frictional coefficient, changed with a range of various surface roughness ratios as well as Reynolds numbers. The result is validated by the comparison with a Moody chart to set the appropriate size of grids at the wall for the correct consideration of surface roughness. The pressure drop in a full-scale U-shaped pipe is measured with the same code, correlated with the surface roughness ratio. In the next stage, we studied a reduced scale model of a U-shaped heat pipe with experiment and analysis of the investigation into fluid-structure interaction (FSI. The material of the pipe was cut from the real heat pipe of a material named Inconel 690 alloy, now used in steam generators. The accelerations at the fixed stations on the outer surface of the pipe model are measured in the series of time history, and Fourier transformed to the frequency domain. The natural frequency of three leading modes were traced from the FFT data, and compared with the result of a numerical analysis for unsteady, incompressible flow. The corresponding mode shapes and maximum displacement are obtained numerically from the FSI simulation with the coupling of the commercial codes, ANSYS-FLUENT and TRANSIENT_STRUCTURAL. The primary frequencies for the model system consist of three parts: structural vibration, BPF(blade pass frequency of pump, and fluid-structure interaction.

  3. Adsorption interaction of carrier-free thallium species with gold and quartz surfaces

    International Nuclear Information System (INIS)

    Serov, A.; Eichler, R.; Tuerler, A.; Wittwer, D.; Gaeggeler, H.W.; Bern Univ.; Dressler, R.; Piquet, D.; Voegele, A.

    2013-01-01

    The adsorption interactions of thallium and its compounds with gold and quartz surfaces were investigated. Carrier-free amounts of thallium were produced in nuclear fusion reactions of alpha particles with thick gold targets. The method chosen for the studies was gas thermochromatography and varying the redox potential of the carrier gases. It was observed that thallium is extremely sensitive to trace amounts of oxygen and water, and can even be oxidized by the hydroxyl groups located on the quartz surface. The experiments on a quartz surface with O 2 , He, H 2 gas in addition with water revealed the formation and deposition of only one thallium species - TlOH. The adsorption enthalpy was determined to be Δ H ads SiO 2 (TlOH) = -134 ± 5 kJ mol -1 . A series of experiments using gold as stationary surface and different carrier gases resulted in the detection of two thallium species - metallic Tl (H 2 as carrier gas) and TlOH (O 2 , O 2 + H 2 O and H 2 + H 2 O as pure carrier gas or carrier gas mixture) with Δ H Au ads (Tl) = -270 ± 10 kJ mol -1 and Δ H Au ads (TlOH) = -146 ± 3 kJ mol -1 . These data demonstrate a weak interaction of TlOH with both quartz and gold surfaces. The data represent important information for the design of future experiments with the heavier homologue of Tl in group 13 of the periodic table - element 113 (E113). (orig.)

  4. Dynamics of intramolecular spin exchange interaction of a nitronyl nitroxide diradical in solution and on surfaces

    Science.gov (United States)

    Lloveras, V.; Badetti, E.; Veciana, J.; Vidal-Gancedo, J.

    2016-02-01

    In this paper we report the study of the dynamics of a thermally modulated intramolecular spin exchange interaction of a novel diradical nitronyl nitroxide-substituted disulfide in solution and when it is grafted on a gold surface. The structure of this diradical was designed to have flexible chains leading to intramolecular collisions and hence spin exchange interaction, and with an appropriate binding group to be grafted on the gold surface to study its behavior on the surface. In solution, this diradical shows a strong spin exchange interaction between both radicals which is modulated by temperature, but also gold nanoparticles (AuNPs) functionalized with this diradical permit investigation of such a phenomenon in surface-grafted radicals. The spin-labelled AuNP synthesis was optimized to obtain high coverage of spin labels to lead to high spin exchange interaction. The obtained AuNPs were studied by Electron Paramagnetic Resonance (EPR), UV-Vis, and IR spectroscopies, HR-TEM microscopy, Cyclic Voltammetry (CV), Energy Dispersive X-ray analysis (EDX) and Thermogravimetric Analysis (TGA). This inorganic-organic hybrid material also showed dipolar interactions between its radicals which were confirmed by the appearance in the EPR spectra of an |Δms| = 2 transition at half-field. This signal gives direct evidence of the presence of a high-spin state and permitted us to study the nature of the magnetic coupling between the spins which was found to be antiferromagnetic. Self-Assembled Monolayers (SAMs) of these radicals on the Au (111) substrate were also prepared and studied by contact angle, X-Ray Photoelectron Spectroscopy (XPS), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), Cyclic Voltammetry and EPR. The magnetic as well as the electrochemical properties of the hybrid surfaces were studied and compared with the properties of this diradical in solution. Analogies between the properties of AuNPs with high coverage of radicals and those of SAM were

  5. Chemical Interaction between U(VI) and Eu(III) ions on a Silica Surface

    International Nuclear Information System (INIS)

    Park, K. K.; Cha, W. S.; Cho, H. R.; Im, H. J.; Jung, E. C.

    2010-01-01

    Understanding the chemical behavior of actinide in groundwater flow is important for assessing the possibility of its migration with water flow in the radioactive waste disposal site. Precipitation/ dissolution in groundwater and adsorption/desorption onto a geological solid surface would determine its migration. The sorption in a geochemical system was expected to be a reaction on a naturally equilibrated surface. However, the construction of a waste disposal facility could disturb this equilibrium state, induce a new reaction environment and affect a nanoscopic surface reaction of actinide. Uranium is ubiquitous in the natural environment and a representative element in a nuclear fuel cycle and in a high level radioactive waste. In oxic environments, it is typically present as uranyl oxocation (UO 2 2+ ), which is easily adsorbed and thereby removed from a solution in the near neutral pH range. This adsorption would form a new surface condition to give an unexpected adsorption behavior for other actinide ions. Eu(III) frequently is used as a chemical analogue of Am(III) and Cm(III) in migration chemistry. The adsorption phenomena has been interpreted with the help of a SCM(surface complexation model). Some spectroscopic techniques such as EPR (Electron Paramagnetic Resonance), IR (InfraRed), EXAFS (Extended X-ray Absorption Fine Structure) and TRLFS (Time Resolved Laser Fluorescence Spectroscopy) have been used for the identification of a modeled adsorbing species. In the case of fluorescence elements, TRLFS has advantages over other techniques for its high sensitivity being proportional to laser source intensity and good selectivity depending on specific transition and lifetime. This technique can be applied to a species on a solid surface not absorbing light such as silica. U(VI) and Eu(III) have fluorescente properties reflecting their coordination structure. In this study, the interaction between U(VI) and Eu(III) on a silica surface was studied by a

  6. Synthesis of water soluble glycine capped silver nanoparticles and their surface selective interaction

    International Nuclear Information System (INIS)

    Agasti, Nityananda; Singh, Vinay K.; Kaushik, N.K.

    2015-01-01

    Highlights: • Synthesis of water soluble silver nanoparticles at ambient reaction conditions. • Glycine as stabilizing agent for silver nanoparticles. • Surface selective interaction of glycine with silver nanoparticles. • Glycine concentration influences crystalinity and optical property of silver nanoparticles. - Abstract: Synthesis of biocompatible metal nanoparticles has been an area of significant interest because of their wide range of applications. In the present study, we have successfully synthesized water soluble silver nanoparticles assisted by small amino acid glycine. The method is primarily based on reduction of AgNO 3 with NaBH 4 in aqueous solution under atmospheric air in the presence of glycine. UV–vis spectroscopy, transmission electron microscopy (TEM), X–ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetry (TG) and differential thermal analysis (DTA) techniques used for characterization of resulting silver nanoparticles demonstrated that, glycine is an effective capping agent to stabilize silver nanoparticles. Surface selective interaction of glycine on (1 1 1) face of silver nanoparticles has been investigated. The optical property and crystalline behavior of silver nanoparticles were found to be sensitive to concentration of glycine. X–ray diffraction studies ascertained the phase specific interaction of glycine on silver nanoparticles. Silver nanoparticles synthesized were of diameter 60 nm. We thus demonstrated an efficient synthetic method for synthesis of water soluble silver nanoparticles capped by amino acid under mild reaction conditions with excellent reproducibility

  7. Interaction of Solid Lipid Nanoparticles and Specific Proteins of the Corona Studied by Surface Plasmon Resonance

    Directory of Open Access Journals (Sweden)

    Mauricio E. Di Ianni

    2017-01-01

    Full Text Available The applications of pharmaceutical and medical nanosystems are among the most intensively investigated fields in nanotechnology. A relevant point to be considered in the design and development of nanovehicles intended for medical use is the formation of the “protein corona” around the nanoparticle, that is, a complex biomolecular layer formed when the nanovehicle is exposed to biological fluids. The chemical nature of the protein corona determines the biological identity of the nanoparticle and influences, among others, the recognition of the nanocarrier by the mononuclear phagocytic system and, thus, its clearance from the blood. Recent works suggest that Surface Plasmon Resonance (SPR, extensively employed for the analysis of biomolecular interactions, can shed light on the formation of the protein corona and its interaction with the surroundings. The synthesis and characterization of solid lipid nanoparticles (SLN coated with polymers of different chemical nature (e.g., polyvinyl alcohol, chitosans are reported. The proof-of-concept for the use of SPR technique in characterizing protein-nanoparticle interactions of surface-immobilized proteins (immunoglobulin G and bovine serum albumin, both involved in the formation of the corona subjected to flowing SLN is demonstrated for non-chitosan-coated nanoparticles. All assayed nanosystems show more preference for IgG than for BSA, such preference being more pronounced in the case of polyvinyl-alcohol-coated SLN.

  8. Molecular dynamics simulations of the DNA interaction with metallic nanoparticles and TiO2 surfaces

    International Nuclear Information System (INIS)

    Kholmurodov, Kh.T.; Krasavin, E.A.; Dushanov, E.B.; Hassan, H.K.; Galal, A.; ElHabashy, H.A.; Sweilam, N.H.; Yasuoka, K.

    2013-01-01

    The understanding of the mechanism of DNA interactions and binding with metallic nanoparticles (NPs) and surfaces represents a great interest in today's medicine applications due to diagnostic and treatment of oncology diseases. Recent experimental and simulation studies involve the DNA interaction with highly localized proton beams or metallic NPs (such as Ag, Au, etc.), aimed at targeted cancer therapy through the injection of metal micro- or nanoparticles into the tumor tissue with consequent local microwave or laser heating. The effects of mutational structure changes in DNA and protein structures could result in destroying of native chemical (hydrogen) bonds or, on the contrary, creating of new bonds that do not normally exist there. The cause of such changes might be the alteration of one or several nucleotides (in DNA) or the substitution of specific amino acid residues (in proteins) that can lead to the essential structural destabilization or unfolding. At the atomic or molecular level, the replacement of one nucleotide by another (in DNA double helices) or replacement of one amino acid residue by another (in proteins) cause essential modifications of the molecular force fields of the environment that break locally important hydrogen bonds underlying the structural stability of the biological molecules. In this work, the molecular dynamics(MD) simulations were performed for four DNA models and the flexibilities of the purine and pyrimidine nucleotides during the interaction process with the metallic NPs and TiO 2 surface were clarified

  9. Use of surface area computations to describe atom-atom interactions.

    Science.gov (United States)

    de La Cruz, X; Calvo, M

    2001-06-01

    Accessible surface (ASA) and atomic contact (ACA) areas are powerful tools for protein structure analysis. However, their use for analysis purposes could be extended if a relationship between them and protein stability could be found. At present, this is the case only for ASAs, which have been used to assess the contribution of the hydrophobic effect to protein stability. In the present work we study whether there is a relationship between atomic contact areas and the free energy associated to atom-atom interactions. We utilise a model in which the contribution of atomic interactions to protein stability is expressed as a linear function of the accessible surface area buried between atom pairs. We assess the validity of this hypothesis, using a set of 124 lysozyme mutants (Matthews, 1995, Adv Protein Chem, 249-278) for which both the X-ray structure and the experimental stability are known. We tested this assumption for residue representations with increasing numbers of atom types. Our results indicate that for simple residue representations, with only 4 to 5 atom types, there is not a clear linear relationship between stability and buried accessible area. However, this relationship is observed for representations with 6 to 9 atom types, where gross heterogeneities in the atom type definition are eliminated. Finally, we also study a version of the linear model in which the atom- atom interactions are represented utilising a simple function for the buried accessible area, which may be useful for protein structure prediction studies.

  10. Surface charge-specific interactions between polymer nanoparticles and ABC transporters in Caco-2 cells

    Science.gov (United States)

    Bhattacharjee, Sourav; van Opstal, Edward J.; Alink, Gerrit M.; Marcelis, Antonius T. M.; Zuilhof, Han; Rietjens, Ivonne M. C. M.

    2013-06-01

    The surface charge-dependent transport of polymeric nanoparticles (PNPs) across Caco-2 monolayers grown on transwell culture systems as an in vitro model for intestinal transport was tested. The transport of well-characterized, monodisperse, and fluorescent tri-block copolymer nanoparticles (TCNPs/size 45 nm) and polystyrene nanoparticles (PSNPs/size 50 nm), with different surface charges (positive and negative), was quantified. The positive PNPs showed a higher intracellular uptake and flux across the Caco-2 monolayers than the negative PNPs. Multidrug resistance/P-glycoprotein (MDR1/P-gp), a specific ATP-binding cassette (ABC) transporter, was found to play a major role in the cellular efflux of positive PNPs, whereas the multidrug resistance protein 1 took part in the efflux of negative PNPs from Caco-2 cells. The positive PNPs also caused an increased cellular uptake and apical to basolateral transport of the carcinogen PhIP across the Caco-2 monolayer. The flavonoid quercetin, which is known to interact with ABC transporters, promoted the intracellular uptake of different PNPs and interfered with the normal distribution patterns of PNPs in the transwell system. These results indicate that PNPs display surface charge-specific interactions with ABC transporters and can even affect the bioavailability of toxic food-borne compounds (like pro-carcinogens).

  11. Surface charge-specific interactions between polymer nanoparticles and ABC transporters in Caco-2 cells

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharjee, Sourav, E-mail: sourav.bhattacharjee@wur.nl [Wageningen University, Laboratory of Organic Chemistry (Netherlands); Opstal, Edward J. van; Alink, Gerrit M. [Wageningen University, Division of Toxicology (Netherlands); Marcelis, Antonius T. M.; Zuilhof, Han [Wageningen University, Laboratory of Organic Chemistry (Netherlands); Rietjens, Ivonne M. C. M. [Wageningen University, Division of Toxicology (Netherlands)

    2013-06-15

    The surface charge-dependent transport of polymeric nanoparticles (PNPs) across Caco-2 monolayers grown on transwell culture systems as an in vitro model for intestinal transport was tested. The transport of well-characterized, monodisperse, and fluorescent tri-block copolymer nanoparticles (TCNPs/size {approx}45 nm) and polystyrene nanoparticles (PSNPs/size {approx}50 nm), with different surface charges (positive and negative), was quantified. The positive PNPs showed a higher intracellular uptake and flux across the Caco-2 monolayers than the negative PNPs. Multidrug resistance/P-glycoprotein (MDR1/P-gp), a specific ATP-binding cassette (ABC) transporter, was found to play a major role in the cellular efflux of positive PNPs, whereas the multidrug resistance protein 1 took part in the efflux of negative PNPs from Caco-2 cells. The positive PNPs also caused an increased cellular uptake and apical to basolateral transport of the carcinogen PhIP across the Caco-2 monolayer. The flavonoid quercetin, which is known to interact with ABC transporters, promoted the intracellular uptake of different PNPs and interfered with the normal distribution patterns of PNPs in the transwell system. These results indicate that PNPs display surface charge-specific interactions with ABC transporters and can even affect the bioavailability of toxic food-borne compounds (like pro-carcinogens).

  12. Interaction-induced singular Fermi surface in a high-temperature oxypnictide superconductor.

    Science.gov (United States)

    Charnukha, A; Thirupathaiah, S; Zabolotnyy, V B; Büchner, B; Zhigadlo, N D; Batlogg, B; Yaresko, A N; Borisenko, S V

    2015-05-21

    In the family of iron-based superconductors, LaFeAsO-type materials possess the simplest electronic structure due to their pronounced two-dimensionality. And yet they host superconductivity with the highest transition temperature Tc ≈ 55K. Early theoretical predictions of their electronic structure revealed multiple large circular portions of the Fermi surface with a very good geometrical overlap (nesting), believed to enhance the pairing interaction and thus superconductivity. The prevalence of such large circular features in the Fermi surface has since been associated with many other iron-based compounds and has grown to be generally accepted in the field. In this work we show that a prototypical compound of the 1111-type, SmFe(0.92)Co(0.08)AsO , is at odds with this description and possesses a distinctly different Fermi surface, which consists of two singular constructs formed by the edges of several bands, pulled to the Fermi level from the depths of the theoretically predicted band structure by strong electronic interactions. Such singularities dramatically affect the low-energy electronic properties of the material, including superconductivity. We further argue that occurrence of these singularities correlates with the maximum superconducting transition temperature attainable in each material class over the entire family of iron-based superconductors.

  13. Surface charge-specific interactions between polymer nanoparticles and ABC transporters in Caco-2 cells

    International Nuclear Information System (INIS)

    Bhattacharjee, Sourav; Opstal, Edward J. van; Alink, Gerrit M.; Marcelis, Antonius T. M.; Zuilhof, Han; Rietjens, Ivonne M. C. M.

    2013-01-01

    The surface charge-dependent transport of polymeric nanoparticles (PNPs) across Caco-2 monolayers grown on transwell culture systems as an in vitro model for intestinal transport was tested. The transport of well-characterized, monodisperse, and fluorescent tri-block copolymer nanoparticles (TCNPs/size ∼45 nm) and polystyrene nanoparticles (PSNPs/size ∼50 nm), with different surface charges (positive and negative), was quantified. The positive PNPs showed a higher intracellular uptake and flux across the Caco-2 monolayers than the negative PNPs. Multidrug resistance/P-glycoprotein (MDR1/P-gp), a specific ATP-binding cassette (ABC) transporter, was found to play a major role in the cellular efflux of positive PNPs, whereas the multidrug resistance protein 1 took part in the efflux of negative PNPs from Caco-2 cells. The positive PNPs also caused an increased cellular uptake and apical to basolateral transport of the carcinogen PhIP across the Caco-2 monolayer. The flavonoid quercetin, which is known to interact with ABC transporters, promoted the intracellular uptake of different PNPs and interfered with the normal distribution patterns of PNPs in the transwell system. These results indicate that PNPs display surface charge-specific interactions with ABC transporters and can even affect the bioavailability of toxic food-borne compounds (like pro-carcinogens).

  14. π-Donors microstructuring on surface of polymer film by their noncovalent interactions with iodine

    Energy Technology Data Exchange (ETDEWEB)

    Traven, Valerii F., E-mail: valerii.traven@gmail.com [Mendeleev University of Chemical Technology, Moscow 125047, Miusskaya sq., 9 (Russian Federation); Ivanov, Ivan V.; Dolotov, Sergei M. [Mendeleev University of Chemical Technology, Moscow 125047, Miusskaya sq., 9 (Russian Federation); Veciana, Jaume Miro; Lebedev, Victor S. [Institut de Ciencia de Materials de Barcelona–CSIC, Campus de la UAB, 08193, Bellaterra (Spain); Shulga, Yurii M.; Khasanov, Salavat S. [Institute of Problems of Chemical Physics, Russian Academy of Sciences, Acad. N.N. Semenov Prosp., 1, Chernogolovka, 142432 (Russian Federation); Medvedev, Michael G. [A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow 119991, Vavilova str., 28 (Russian Federation); Laukhina, Elena E. [The Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine, ICMAB-CSIC, Bellaterra, 08193 (Spain)

    2015-06-15

    Noncovalent (charge transfer) interaction between perylene and iodine in polycarbonate film provides formation of microstructured perylene layer on the polymer surface upon exposure of polymer film which contains dissolved perylene to solvent + iodine vapors. The prepared bilayer film possesses a sensing effect to iodine vapors which can be observed by both fluorescence and electrical conductivity changes. Similar bilayer films have been prepared also with anthracene and phenothiazine as π-donors with use of different polymer matrixes. Interaction of iodine with polycyclic aromatic hydrocarbons (PAH) has also been studied by the M06-2x DFT calculations for better understanding of phenomenon of π-donors microstructuring on surface of polymer film. - Highlights: • Preparation of bilayer polymer films with π-donors on surface for the first time. • π-Donor phase purity is confirmed by XRD, IR spectroscopy, SEM. • Perylene bilayer polymer films possess fluorescence. • Perylene bilayer polymer films loss fluorescence under iodine vapors. • Perylene bilayer polymer films possess electrical conductivity when treated by iodine vapors.

  15. Spontaneous surface self-assembly in protein-surfactant mixtures: interactions between hydrophobin and ethoxylated polysorbate surfactants.

    Science.gov (United States)

    Tucker, Ian M; Petkov, Jordan T; Penfold, Jeffrey; Thomas, Robert K; Li, Peixun; Cox, Andrew R; Hedges, Nick; Webster, John R P

    2014-05-08

    The synergistic interactions between certain ethoxylated polysorbate nonionic surfactants and the protein hydrophobin result in spontaneous self-assembly at the air-water interface to form layered surface structures. The surface structures are characterized using neutron reflectivity. The formation of the layered surface structures is promoted by the hydrophobic interaction between the polysorbate alkyl chain and the hydrophobic patch on the surface of the globular hydrophobin and the interaction between the ethoxylated sorbitan headgroup and hydrophilic regions of the protein. The range of the ethoxylated polysorbate concentrations over which the surface ordering occurs is a maximum for the more hydrophobic surfactant polyoxyethylene(8) sorbitan monostearate. The structures at the air-water interface are accompanied by a profound change in the wetting properties of the solution on hydrophobic substrates. In the absence of the polysorbate surfactant, hydrophobin wets a hydrophobic surface, whereas the hydrophobin/ethoxylated polysorbate mixtures where multilayer formation occurs result in a significant dewetting of hydrophobic surfaces. The spontaneous surface self-assembly for hydrophobin/ethoxylated polysorbate surfactant mixtures and the changes in surface wetting properties provide a different insight into protein-surfactant interactions and potential for manipulating surface and interfacial properties and protein surface behavior.

  16. Surfactant-assisted growth of anodic nanoporous niobium oxide with a grained surface

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Jeong Eun [Department of Chemical Engineering, Inha University, 253 Yonghyun Dong, Nam-Gu, Incheon 402-751 (Korea, Republic of); Choi, Jinsub, E-mail: jinsub@inha.ac.k [Department of Chemical Engineering, Inha University, 253 Yonghyun Dong, Nam-Gu, Incheon 402-751 (Korea, Republic of)

    2010-07-15

    Nanoporous niobium oxide film with a maximum thickness of 520 nm was prepared by anodizing niobium in a mixture of 1 wt% HF, 1 M H{sub 3}PO{sub 4}, and a small amount of Sodium Dodecyl Sulfate (SDS) surfactant. The porosity of the anodic niobium oxide prepared without SDS is irregular with the surface of the oxide suggesting a grained surface pattern rather than an ordered porous structure. A proper amount of SDS addition can prepare a pore arrangement with stripe patterns. The pore depth and surface pattern were strongly affected by the concentration of SDS and bath temperature. We found that the addition of SDS surfactant facilitated improvement in the chemical resistance of niobium oxide, leading to the formation of pores with a longer length compared to those prepared without a SDS surfactant. This can be in part ascribed to the protection of the surface by the physical adsorption of SDS on the surface due to a charge-charge interaction and be in part attributed to the formation of Nb=O bonding on the outermost oxide layer by SDS. When anodization was carried out for 4 h, the surface dissolution of niobium oxide was observed, which means that the maximum tolerance time against chemical dissolution was less than 4 h.

  17. Computational model of the interaction of a helium atmospheric-pressure jet with a dielectric surface

    Science.gov (United States)

    Hasan, M. I.; Bradley, J. W.

    2015-11-01

    Using a time-dependent two-dimensional axisymmetric fluid model the interaction of a plasma jet with a dielectric surface has been studied. The model is solved for two consecutive periods of a positive unipolar pulsed waveform. The study concentrates on determining the fluxes of the main oxygen ion species, \\text{O}2+ , \\text{O}2- and the total accumulated charge on the surface. Approaching the dielectric surface, the streamer head is seen to divert its direction of propagation, spreading out radially approximately 0.2 mm above the dielectric surface. For \\text{O}2+ generated near the streamer head, this leads to a maximum in their flux to the surface which moves radially outwards with the streamer propagation, driven by the applied electric field in pulse on-time. In the off-time, the flux of \\text{O}2+ drops by at least two orders of magnitude. As a result, the total number of \\text{O}2+ ions arriving at the surface over one entire pulse period (fluence) has an annular shape limited by the effective contact area of the streamer on the surface. In contrast \\text{O}2- ions generated in the pulse on-time do not reach the surface due to the direction of the applied electric field. In the off-time, \\text{O}2- ions generated at the edges of the deformed streamer are pushed by the accumulated surface charge outwards. As a result, the \\text{O}2- fluence has an annular structure with its maximum being outside the area of the dielectric surface covered by the plasma channel. Solving for the second pulse period shows small changes in the predicted fluences, with largest difference seen with \\text{O}2- . We see that increasing the flow rate (by a factor of three) shifts the position of the maximum fluence of \\text{O}2+ outwards, and decreasing the \\text{O}2- fluence in the second pulse period.

  18. The surface interactions of a near-neutral carbon nanoparticle tracer with calcite

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yan Vivian, E-mail: yan.li@colostate.edu [Colorado State University, Department of Design and Merchandising (United States); Cathles, Lawrence M., E-mail: lmc19@cornell.edu [Cornell University, Earth and Atmospheric Sciences (United States)

    2016-03-15

    A new class of nearly charge-neutral carbon-cored nanoparticle tracers are remarkably non-interactive with solid surfaces and could provide a valuable baseline for diverse hydrological and environmental studies of subsurface flow and particle transport. We investigate the causes of inertness by studying the interactions with calcite of a nanoparticle of this class synthesized from malic acid and ethanolamine (M-dots) dispersed in brine (NaCl, CaCl{sub 2}, and MgCl{sub 2}) solutions. None of the M-dots are retained in calcite sand-packed columns when dispersed in DI water. Dispersed in the NaCl and mixed brine solutions, 5.6 % of and 7.3 % of the M-dots are initially retained, but 65 and 13 % of these retained particles are subsequently released when the column is flushed with DI water. When dispersed in the CaCl{sub 2} and MgCl{sub 2} solutions, 65 and 54 % of the M-dots are initially retained, and 28 and 26 % subsequently released in the DI water flush. The M-dots have a small negative zeta potential in all solutions, but the calcite zeta potential changes from strongly negative to strongly positive across the solution series, and the particle retention tracks this change. Derjaguin–Landau–Verwey–Overbeek (DLVO) modeling of the force between a calcite probe and an M-dot coated surface shows that hydration forces repel the particles in the DI water, NaCl, and mixed solutions, but not in the CaCl{sub 2} and MgCl{sub 2} solutions. These results show that near-zero charge and strongly hydrophilic decoration are the causes of the remarkable inertness of carbon-cored nanoparticles, and also suggest that nanoparticles could be useful in solute-surface interaction studies.Graphical Abstract.

  19. The surface interactions of a near-neutral carbon nanoparticle tracer with calcite

    International Nuclear Information System (INIS)

    Li, Yan Vivian; Cathles, Lawrence M.

    2016-01-01

    A new class of nearly charge-neutral carbon-cored nanoparticle tracers are remarkably non-interactive with solid surfaces and could provide a valuable baseline for diverse hydrological and environmental studies of subsurface flow and particle transport. We investigate the causes of inertness by studying the interactions with calcite of a nanoparticle of this class synthesized from malic acid and ethanolamine (M-dots) dispersed in brine (NaCl, CaCl 2 , and MgCl 2 ) solutions. None of the M-dots are retained in calcite sand-packed columns when dispersed in DI water. Dispersed in the NaCl and mixed brine solutions, 5.6 % of and 7.3 % of the M-dots are initially retained, but 65 and 13 % of these retained particles are subsequently released when the column is flushed with DI water. When dispersed in the CaCl 2 and MgCl 2 solutions, 65 and 54 % of the M-dots are initially retained, and 28 and 26 % subsequently released in the DI water flush. The M-dots have a small negative zeta potential in all solutions, but the calcite zeta potential changes from strongly negative to strongly positive across the solution series, and the particle retention tracks this change. Derjaguin–Landau–Verwey–Overbeek (DLVO) modeling of the force between a calcite probe and an M-dot coated surface shows that hydration forces repel the particles in the DI water, NaCl, and mixed solutions, but not in the CaCl 2 and MgCl 2 solutions. These results show that near-zero charge and strongly hydrophilic decoration are the causes of the remarkable inertness of carbon-cored nanoparticles, and also suggest that nanoparticles could be useful in solute-surface interaction studies.Graphical Abstract

  20. The surface interactions of a near-neutral carbon nanoparticle tracer with calcite

    KAUST Repository

    Li, Yan Vivian

    2016-03-02

    A new class of nearly charge-neutral carbon-cored nanoparticle tracers are remarkably non-interactive with solid surfaces and could provide a valuable baseline for diverse hydrological and environmental studies of subsurface flow and particle transport. We investigate the causes of inertness by studying the interactions with calcite of a nanoparticle of this class synthesized from malic acid and ethanolamine (M-dots) dispersed in brine (NaCl, CaCl2, and MgCl2) solutions. None of the M-dots are retained in calcite sand-packed columns when dispersed in DI water. Dispersed in the NaCl and mixed brine solutions, 5.6 % of and 7.3 % of the M-dots are initially retained, but 65 and 13 % of these retained particles are subsequently released when the column is flushed with DI water. When dispersed in the CaCl2 and MgCl2 solutions, 65 and 54 % of the M-dots are initially retained, and 28 and 26 % subsequently released in the DI water flush. The M-dots have a small negative zeta potential in all solutions, but the calcite zeta potential changes from strongly negative to strongly positive across the solution series, and the particle retention tracks this change. Derjaguin–Landau–Verwey–Overbeek (DLVO) modeling of the force between a calcite probe and an M-dot coated surface shows that hydration forces repel the particles in the DI water, NaCl, and mixed solutions, but not in the CaCl2 and MgCl2 solutions. These results show that near-zero charge and strongly hydrophilic decoration are the causes of the remarkable inertness of carbon-cored nanoparticles, and also suggest that nanoparticles could be useful in solute-surface interaction studies.

  1. Interaction of cw CO2 laser radiation with plasma near-metallic substrate surface

    Science.gov (United States)

    Azharonok, V. V.; Astapchik, S. A.; Zabelin, Alexandre M.; Golubev, Vladimir S.; Golubev, V. S.; Grezev, A. N.; Filatov, Igor V.; Chubrik, N. I.; Shimanovich, V. D.

    2000-07-01

    Optical and spectroscopic methods were used in studying near-surface plasma that is formed under the effect CW CO2 laser of (2- 5)x106W/cm2 power density upon stainless steel in He and Ar shielding gases. The variation of plume spatial structure with time has been studied, the outflow of gas-vapor jets from the interaction area has been characterized. The spectra of plasma plume pulsations have been obtained for the frequency range Δf = 0-1 MHz. The temperature and electron concentration of plasma plume have been found under radiation effect upon the target of stainless steel. Consideration has been given to the most probable mechanisms of CW laser radiation-metal non-stationary interaction.

  2. On the mechanical interaction between a fluid-filled fracture and the earth's surface

    Science.gov (United States)

    Pollard, D.D.; Holzhausen, G.

    1979-01-01

    The mechanical interaction between a fluid-filled fracture (e.g., hydraulic fracture joint, or igneous dike) and the earth's surface is analyzed using a two-dimensional elastic solution for a slit of arbitrary inclination buried beneath a horizontal free surface and subjected to an arbitrary pressure distribution. The solution is obtained by iteratively superimposing two fundamental sets of analytical solutions. For uniform internal pressure the slit behaves essentially as if it were in an infinite region if the depth-to-center is three times greater than the half-length. For shallower slits interaction with the free surface is pronounced: stresses and displacements near the slit differ by more than 10% from values for the deeply buried slit. The following changes are noted as the depth-to-center decreases: 1. (1) the mode I stress intensity factor increases for both ends of the slit, but more rapidly at the upper end; 2. (2) the mode II stress-intensity factor is significantly different from zero (except for vertical slits) suggesting propagation out of the original plane of the slit; 3. (3) displacements of the slit wall are asymmetric such that the slit gaps open more widely near the upper end. Similar changes are noted if fluid density creates a linear pressure gradient that is smaller than the lithostatic gradient. Under such conditions natural fractures should propagate preferentially upward toward the earth's surface requiring less pressure as they grow in length. If deformation near the surface is of interest, the model should account explicitly for the free surface. Stresses and displacements at the free surface are not approximated very well by values calculated along a line in an infinite region, even when the slit is far from the line. As depth-to-center of a shallow pressurized slit decreases, the following changes are noted: 1. (1) displacements of the free surface increase to the same order of magnitude as the displacements of the slit walls, 2. (2

  3. Negatively charged ions on Mg(0001) surfaces: appearance and origin of attractive adsorbate-adsorbate interactions.

    Science.gov (United States)

    Cheng, Su-Ting; Todorova, Mira; Freysoldt, Christoph; Neugebauer, Jörg

    2014-09-26

    Adsorption of electronegative elements on a metal surface usually leads to an increase in the work function and decrease in the binding energy as the adsorbate coverage rises. Using density-functional theory calculations, we show that Cl adsorbed on a Mg(0001) surface complies with these expectations, but adsorption of {N,O,F} causes a decrease in the work function and an increase in the binding energy. Analyzing the electronic structure, we show that the presence of a highly polarizable electron spill-out in front of Mg(0001) causes this unusual adsorption behavior and is responsible for the appearance of a hitherto unknown net-attractive lateral electrostatic interaction between same charged adsorbates.

  4. Interactions of Lysozyme and Azobenzene Derivatives in the Solution and on a Surface

    Science.gov (United States)

    Wei, Tao; Shing, Katherine

    2015-03-01

    The reversible isomerization of the azobenzene and its derivatives can control protein structure in an aqueous environment with the alternation of visible and UV lights for very promising applications in drug delivery. However, an atomistic description of Azo-molecules and protein amino acid residues is still lacking. In this study we performed atomistic molecular dynamics simulation to study the interactions between a lysozyme molecule and the Azobenzene derivative (in the bulk solution and grafted on the Silica surfaces). Protein structural arrangements (i.e., the shape and secondary structures) and its mobility, as a function of tran/cis ratio in the bulk solution and on the self-assembling monolayer surface's density and morphology, are systematically investigated.

  5. Interaction of water with faceted NiO(1 1 1) surface tuned by films thickness

    Science.gov (United States)

    Liu, Lixia; Wang, Shuai; Liu, Shuming; Guo, Qinlin; Guo, Jiandong

    2018-01-01

    The interaction of water with the polar surface of NiO(1 1 1) films has been investigated using various in situ surface analytical techniques, as well as ex situ scanning electron microscopy and atomic force microscopy. The {1 0 0} facets are formed on NiO(1 1 1) films upon annealing. The boundary between {1 0 0} facet and bare (1 1 1) face and the corner on the facet can facilitate dissociation of water. The total boundary length and the number of corner sites vary with film thickness. The dissociated hydroxyls are thermally stable up to 700 K on the thinner films. Consequently the activity of water dissociation can be tuned by adjusting the film thickness.

  6. Controlling Nanocrystal Superlattice Symmetry and Shape-Anisotropic Interactions through Variable Ligand Surface Coverage

    KAUST Repository

    Choi, Joshua J.

    2011-03-09

    The assembly of colloidal nanocrystals (NCs) into superstructures with long-range translational and orientational order is sensitive to the molecular interactions between ligands bound to the NC surface. We illustrate how ligand coverage on colloidal PbS NCs can be exploited as a tunable parameter to direct the self-assembly of superlattices with predefined symmetry. We show that PbS NCs with dense ligand coverage assemble into face-centered cubic (fcc) superlattices whereas NCs with sparse ligand coverage assemble into body-centered cubic (bcc) superlattices which also exhibit orientational ordering of NCs in their lattice sites. Surface chemistry characterization combined with density functional theory calculations suggest that the loss of ligands occurs preferentially on {100} than on reconstructed {111} NC facets. The resulting anisotropic ligand distribution amplifies the role of NC shape in the assembly and leads to the formation of superlattices with translational and orientational order. © 2011 American Chemical Society.

  7. Natural convection - radiation interaction in boundary layer flow over horizontal surfaces

    International Nuclear Information System (INIS)

    Ali, M.M.; Chen, T.S.; Armaly, B.F.

    1982-01-01

    A numerical model is developed for natural convection-radiation interaction in the boundary layer over a semi-infinite horizontal flat plate with one hot and one cold surface. The fluid is assumed to be gray, to emit, absorb, be nonscattering, and constant with a density variation in the vertical direction, which induces a buoyancy force. Two-dimensional, boundary-layer equations are defined, and the radiative heat flux is simplified using a Rosseland approximation. Conservation equations are transformed into a system of nonlinear ordinary differential equations which can be solved simultaneously with a Runge-Kutta integration scheme, along with the Newton-Raphson shooting technique. The thermal radiation is found to enhance the wall shear stress and the surface heat transfer rate on both the hot and cold sides

  8. Second generation diffusion model of interacting gravity waves on the surface of deep fluid

    Directory of Open Access Journals (Sweden)

    A. Pushkarev

    2004-01-01

    Full Text Available We propose a second generation phenomenological model for nonlinear interaction of gravity waves on the surface of deep water. This model takes into account the effects of non-locality of the original Hasselmann diffusion equation still preserving important properties of the first generation model: physically consistent scaling, adherence to conservation laws and the existence of Kolmogorov-Zakharov solutions. Numerical comparison of both models with the original Hasselmann equation shows that the second generation models improves the angular distribution in the evolving wave energy spectrum.

  9. Magnetic moments in calcium isotopes via a surface-interaction experiment

    International Nuclear Information System (INIS)

    Niv, Y.; Hass, M.; Zemel, A.; Goldring, G.

    1979-01-01

    A rotation of the angular correlation of de-excitation γ-rays from 40 Ca and 44 Ca was observed in a tilted foil geometry. The signs and magnitudes of the magnetic moments of the 2 1 + of 44 Ca and of the 3 1 - level of 40 Ca were determined to be g = -0.28+-0.11 and g = +0.52+-0.18, respectively. This experiment provides further information regarding the polarization of deeply bound electronic configurations produced by a surface-interaction mechanism and demonstrates the feasibility of the present technique for measuring signs and magnitudes of magnetic moments of picosecond nuclear levels. (author)

  10. Proceedings of the joint meeting on Plasma Surface Interaction (PSI) and Plasma Facing Components (PFC)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-03-01

    The joint meeting on Plasma Surface Interaction (PSI) and Plasma Facing Components (PFC) was held in Naka Fusion Establishment on December 1, 2000. This meeting has been held to enhance information exchange between PSI and PFC researchers. In the present meeting, there were 11 presentations which covered current status of PSI and PFC studies for large fusion devices such as ITER, JT-60 and LHD, and basic studies on Hydrogen isotope behavior in the fusion material. This report includes abstracts and view graphs of these presentations. (author)

  11. Weakly Hydrated Surfaces and the Binding Interactions of Small Biological Solutes

    Energy Technology Data Exchange (ETDEWEB)

    Brady, J. W.; Tavagnacco, L.; Ehrlich, L.; Chen, M.; Schnupf, U.; Himmel, M. E.; Saboungi, M. L.; Cesaro, A.

    2012-04-01

    Extended planar hydrophobic surfaces, such as are found in the side chains of the amino acids histidine, phenylalanine, tyrosine, and tryptophan, exhibit an affinity for the weakly hydrated faces of glucopyranose. In addition, molecular species such as these, including indole, caffeine, and imidazole, exhibit a weak tendency to pair together by hydrophobic stacking in aqueous solution. These interactions can be partially understood in terms of recent models for the hydration of extended hydrophobic faces and should provide insight into the architecture of sugar-binding sites in proteins.

  12. Improving Acousto-Optical Interaction by Mechanical Resonators on a Surface

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard; Laude, Vincent; Khelif, Abdelkrim

    The finite element method is employed to model surface acoustic waves generated by high aspect ratio electrodes and their interaction with an optical wave in a waveguide. With a periodic model it is first shown that these electrodes act as a mechanical resonator, which introduces several confined...... modes with slow phase velocities because of mechanical energy storage. The periodic model is extended to a finite model by using perfectly matched layers at the boundaries and the periodic and the finite model are in fine agreement. The finite model is then employed to study the acousto...

  13. Quantum corrected Langevin dynamics for adsorbates on metal surfaces interacting with hot electrons

    DEFF Research Database (Denmark)

    Olsen, Thomas; Schiøtz, Jakob

    2010-01-01

    We investigate the importance of including quantized initial conditions in Langevin dynamics for adsorbates interacting with a thermal reservoir of electrons. For quadratic potentials the time evolution is exactly described by a classical Langevin equation and it is shown how to rigorously obtain...... mechanical master equation approach. With CO on Cu(100) as an example, we demonstrate the effect for a system with ab initio frictional tensor and potential energy surfaces and show that quantizing the initial conditions can have a large impact on both the desorption probability and the distribution...

  14. Role of plasma membrane surface charges in dictating the feasibility of membrane-nanoparticle interactions

    Science.gov (United States)

    Sinha, Shayandev; Jing, Haoyuan; Sachar, Harnoor Singh; Das, Siddhartha

    2017-12-01

    Receptor-ligand (R-L) binding mediated interactions between the plasma membrane (PM) and a nanoparticle (NP) require the ligand-functionalized NPs to come to a distance of separation (DOS) of at least dRL (length of the R-L complex) from the receptor-bearing membranes. In this letter, we establish that the membrane surface charges and the surrounding ionic environment dictate whether or not the attainment of such a critical DOS is possible. The negatively charged membrane invariably induces a negative electrostatic potential at the NP surface, repelling the NP from the membrane. This is countered by the attractive influences of the thermal fluctuations and van der Waals (vdw) interactions that drive the NP close to the membrane. For a NP approaching the membrane from a distance, the ratio of the repulsive (electrostatic) and attractive (thermal and vdW) effects balances at a critical NP-membrane DOS of dg,c. For a given set of parameters, there can be two possible values of dg,c, namely, dg,c,1 and dg,c,2 with dg,c,1 ≫ dg,c,2. We establish that any R-L mediated NP-membrane interaction is possible only if dRL > dg,c,1. Therefore, our study proposes a design criterion for engineering ligands for a NP that will ensure the appropriate length of the R-L complex in order to ensure the successful membrane-NP interaction in the presence of a given electrostatic environment. Finally, we discuss the manner in which our theory can help designing ligand-grafted NPs for targeted drug delivery, design biomimetics NPs, and also explain various experimental results.

  15. Interaction between mouse adenovirus type 1 and cell surface heparan sulfate proteoglycans.

    Science.gov (United States)

    Lenaerts, Liesbeth; van Dam, Wim; Persoons, Leentje; Naesens, Lieve

    2012-01-01

    Application of human adenovirus type 5 (Ad5) derived vectors for cancer gene therapy has been limited by the poor cell surface expression, on some tumor cell types, of the primary Ad5 receptor, the coxsackie-adenovirus-receptor (CAR), as well as the accumulation of Ad5 in the liver following interaction with blood coagulation factor X (FX) and subsequent tethering of the FX-Ad5 complex to heparan sulfate proteoglycan (HSPG) on liver cells. As an alternative vector, mouse adenovirus type 1 (MAV-1) is particularly attractive, since this non-human adenovirus displays pronounced endothelial cell tropism and does not use CAR as a cellular attachment receptor. We here demonstrate that MAV-1 uses cell surface heparan sulfate proteoglycans (HSPGs) as primary cellular attachment receptor. Direct binding of MAV-1 to heparan sulfate-coated plates proved to be markedly more efficient compared to that of Ad5. Experiments with modified heparins revealed that the interaction of MAV-1 to HSPGs depends on their N-sulfation and, to a lesser extent, 6-O-sulfation rate. Whereas the interaction between Ad5 and HSPGs was enhanced by FX, this was not the case for MAV-1. A slot blot assay demonstrated the ability of MAV-1 to directly interact with FX, although the amount of FX complexed to MAV-1 was much lower than observed for Ad5. Analysis of the binding of MAV-1 and Ad5 to the NCI-60 panel of different human tumor cell lines revealed the preference of MAV-1 for ovarian carcinoma cells. Together, the data presented here enlarge our insight into the HSPG receptor usage of MAV-1 and support the development of an MAV-1-derived gene vector for human cancer therapy.

  16. Interaction between mouse adenovirus type 1 and cell surface heparan sulfate proteoglycans.

    Directory of Open Access Journals (Sweden)

    Liesbeth Lenaerts

    Full Text Available Application of human adenovirus type 5 (Ad5 derived vectors for cancer gene therapy has been limited by the poor cell surface expression, on some tumor cell types, of the primary Ad5 receptor, the coxsackie-adenovirus-receptor (CAR, as well as the accumulation of Ad5 in the liver following interaction with blood coagulation factor X (FX and subsequent tethering of the FX-Ad5 complex to heparan sulfate proteoglycan (HSPG on liver cells. As an alternative vector, mouse adenovirus type 1 (MAV-1 is particularly attractive, since this non-human adenovirus displays pronounced endothelial cell tropism and does not use CAR as a cellular attachment receptor. We here demonstrate that MAV-1 uses cell surface heparan sulfate proteoglycans (HSPGs as primary cellular attachment receptor. Direct binding of MAV-1 to heparan sulfate-coated plates proved to be markedly more efficient compared to that of Ad5. Experiments with modified heparins revealed that the interaction of MAV-1 to HSPGs depends on their N-sulfation and, to a lesser extent, 6-O-sulfation rate. Whereas the interaction between Ad5 and HSPGs was enhanced by FX, this was not the case for MAV-1. A slot blot assay demonstrated the ability of MAV-1 to directly interact with FX, although the amount of FX complexed to MAV-1 was much lower than observed for Ad5. Analysis of the binding of MAV-1 and Ad5 to the NCI-60 panel of different human tumor cell lines revealed the preference of MAV-1 for ovarian carcinoma cells. Together, the data presented here enlarge our insight into the HSPG receptor usage of MAV-1 and support the development of an MAV-1-derived gene vector for human cancer therapy.

  17. Extensional terrain formation on Europa and Ganymede: Implications for ocean-surface interaction

    Science.gov (United States)

    Howell, S. M.; Pappalardo, R. T.

    2017-12-01

    Europa and Ganymede, Galilean satellites of Jupiter, exhibit geologic activity in their outer H2O ice shells that might convey material from water oceans within the satellites to their surfaces. Imagery from the Voyager and Galileo spacecraft reveal surfaces rich with tectonic deformation, including dilational bands on Europa and groove lanes on Ganymede. These features are generally attributed to the extension of a brittle ice lithosphere overlaying a possibly convecting ice asthenosphere. To explore band formation and interaction with interior oceans, we employ fully visco-elasto-plastic 2-D models of faulting and convection with complex, realistic pure ice rheologies. In these models, material entering from below is tracked and considered to be "fossilized ocean," ocean material that has frozen into the ice shell and evolves through geologic time. We track the volume fraction of fossil ocean material in the ice shell as a function of depth, and the exposure of both fresh ice and fossil ocean material at the ice shell surface. We vary ice shell thickness, fault localization, melting-temperature ice viscosity, and the presence of pre-existing weaknesses. Mechanisms which act to weaken the ice shell and thin the lithosphere (e.g. vigorous convection, thinner shells, pre-existing weaknesses) tend to plastically yield to form smooth bands at high strains, and are more likely to incorporate fossil ocean material in the ice shell and expose it at the surface. In contrast, lithosphere strengthened by rapid fault annealing or increased viscosity, for example, exhibits large-scale tectonic rifting at low strains superimposed over pre-existing terrains, and inhibits the incorporation and delivery of fossil ocean material to the surface. Thus, our results identify a spectrum of extensional terrain formation mechanisms as linked to lithospheric strength, rather than any specific mechanism being unique to each type of band, and where in this spectrum ocean material

  18. Does soccer cleat design influence the rotational interaction with the playing surface?

    Science.gov (United States)

    Galbusera, Fabio; Tornese, Davide Zai; Anasetti, Federica; Bersini, Simone; Volpi, Piero; La Barbera, Luigi; Villa, Tomaso

    2013-09-01

    Non-contact injuries in soccer players may be related to the interplay between cleat type and playing surface, and bladed shoes were often blamed for non-contact injuries with no research support. The aim of this study was to compare the rotational resistance (stiffness and peak sustainable torque) among three types of soccer cleats (metal studs, molded rubber studs, and bladed) in a controlled laboratory environment. The shoes were tested on both natural and artificial turfs under a compressive preload of 1000 N and with internal and external rotations. The three shoe models showed comparable performances with a good repeatability for each individual test on both playing surfaces. A less stiff behavior was observed for the natural turf. A tendency toward highest peak torque was observed in the studded model on natural surface. The bladed cleats provided peak torque and rotational stiffness comparable to the other models. Studded and bladed cleats did not significantly differ in their interaction with the playing surface. Therefore, soccer shoes with bladed cleats should not be banned in the context of presumed higher risk for non-contact injuries.

  19. In situ nanoscale observations of metatorbernite surfaces interacted with aqueous solutions.

    Science.gov (United States)

    Astilleros, José Manuel; Pinto, André Jorge; Gonçalves, Mário A; Sánchez-Pastor, Nuria; Fernández-Díaz, Lurdes

    2013-03-19

    Metatorbernite (Cu(UO(2))(2)(PO(4))(2)·8H(2)O) has been identified in contaminated sediments as a phase controlling the fate of U. Here, we applied atomic force microscopy (AFM) to observe in situ the interaction between metatorbernite cleavage surfaces and flowing aqueous solutions (residence time = 1 min) with different pHs. In contact with deionized water the features of (001) surfaces barely modify. However, changes are remarkable both under acidic and basic conditions. In acidic solutions (pH = 2.5) metatorbernite surface develops a rough altered layer and large pits nucleate on it. The altered layer shows a low adhesion and is removed by the AFM tip during the scanning. The large pits spread rapidly, at few tens of nm/s, indicating a collapse of the structure. The combination of dissolution and the presence of defects in the metatorbernite structure can explain both the collapse process and the alteration of the surfaces under acidic conditions. Other mechanisms such as ion exchange reactions remain speculative. In NaOH solutions (pH = 11.5) metatorbernite dissolves by formation of etch pits bounded by steps parallel to [100], the direction of the most straight periodic bond chains (PBCs) in metatorbernite structure. These steps retreat at ∼0.15 nm/s. Under these conditions dissolution is promoted by the formation of stable uranyl carbonate complexes in solution.

  20. Numerical investigation of interactions of multiple spherical shock waves between themselves and with the underlying surface

    Science.gov (United States)

    Andrushchenko, V. A.; Murashkin, I. V.; Shevelev, Yu. D.

    2016-06-01

    Within the investigation of various aspects of asteroid and comet danger and, in particular, the explosion of several fragments of meteoroids in the atmosphere above the Earth surface, the toy problem about four point explosions in the case of their special arrangement above the underlying surface is numerically solved. Complex interactions of primary and secondary shock waves between themselves, with the hard surface, and with tangential discontinuities are examined. The structure of flow inside gas regions disturbed by the explosions—the occurrence of eddy structures in them and the influence of reflected shocks waves on them—are investigated. The tendency of the external wave fronts of each explosion to form a unified front and the tendency of their internal hot domains to merge into a joined configuration (where the second process proceeds a little later than the first one) is revealed. This unified front and joined configuration are qualitatively identical to the external internal structure for the solitary explosion. The specially arranged explosions are chosen because the effects of multiple diffraction, interference, and, the main thing, cumulation of spherical waves are manifested more clearly in this caseTwo variants with different altitude of the explosions above the surface are calculated.

  1. Groundwater-surface water interactions in a large semi-arid floodplain: implications for salinity management

    Science.gov (United States)

    Lamontagne, Sébastien; Leaney, Fred W.; Herczeg, Andrew L.

    2005-10-01

    Flow regulation and water diversion for irrigation have considerably impacted the exchange of surface water between the Murray River and its floodplains. However, the way in which river regulation has impacted groundwater-surface water interactions is not completely understood, especially in regards to the salinization and accompanying vegetation dieback currently occurring in many of the floodplains. Groundwater-surface water interactions were studied over a 2 year period in the riparian area of a large floodplain (Hattah-Kulkyne, Victoria) using a combination of piezometric surface monitoring and environmental tracers (Cl-, 2H, and 18O). Despite being located in a local and regional groundwater discharge zone, the Murray River is a losing stream under low flow conditions at Hattah-Kulkyne. The discharge zone for local groundwater, regional groundwater and bank recharge is in the floodplain within 1 km of the river and is probably driven by high rates of transpiration by the riparian Eucalyptus camaldulensis woodland. Environmental tracers data suggest that the origin of groundwater is principally bank recharge in the riparian zone and a combination of diffuse rainfall recharge and localized floodwater recharge elsewhere in the floodplain. Although the Murray River was losing under low flows, bank discharge occurred during some flood recession periods. The way in which the water table responded to changes in river level was a function of the type of stream bank present, with point bars providing a better connection to the alluvial aquifer than the more common clay-lined banks. Understanding the spatial variability in the hydraulic connection with the river channel and in vertical recharge following inundations will be critical to design effective salinity remediation strategies for large semi-arid floodplains.

  2. Biomaterial design for specific cellular interactions: Role of surface functionalization and geometric features

    Science.gov (United States)

    Kolhar, Poornima

    The areas of drug delivery and tissue engineering have experienced extraordinary growth in recent years with the application of engineering principles and their potential to support and improve the field of medicine. The tremendous progress in nanotechnology and biotechnology has lead to this explosion of research and development in biomedical applications. Biomaterials can now be engineered at a nanoscale and their specific interactions with the biological tissues can be modulated. Various design parameters are being established and researched for design of drug-delivery carriers and scaffolds to be implanted into humans. Nanoparticles made from versatile biomaterial can deliver both small-molecule drugs and various classes of bio-macromolecules, such as proteins and oligonucleotides. Similarly in the field of tissue engineering, current approaches emphasize nanoscale control of cell behavior by mimicking the natural extracellular matrix (ECM) unlike, traditional scaffolds. Drug delivery and tissue engineering are closely connected fields and both of these applications require materials with exceptional physical, chemical, biological, and biomechanical properties to provide superior therapy. In the current study the surface functionalization and the geometric features of the biomaterials has been explored. In particular, a synthetic surface for culture of human embryonic stem cells has been developed, demonstrating the importance of surface functionalization in maintaining the pluripotency of hESCs. In the second study, the geometric features of the drug delivery carriers are investigated and the polymeric nanoneedles mediated cellular permeabilization and direct cytoplasmic delivery is reported. In the third study, the combined effect of surface functionalization and geometric modification of carriers for vascular targeting is enunciated. These studies illustrate how the biomaterials can be designed to achieve various cellular behaviors and control the

  3. Overview of the plasma-surface interaction on limiter surfaces in the startup campaign of Wendelstein 7-X

    Science.gov (United States)

    Winters, V. R.; Brezinsek, S.; Effenberg, F.; Rasinski, M.; Schmitz, O.; Stephey, L.; Biedermann, C.; Dhard, C. P.; Frerichs, H.; Harris, J.; Krychowiak, M.; König, R.; Pedersen, T. Sunn; Wurden, G. A.; the W7-X Team

    2017-12-01

    The first operational campaign of Wendelstein 7-X (W7-X) provided an excellent environment for the study of plasma-surface interaction (PSI) in a stellarator. In situ spectroscopic analysis via a combined visible/infrared camera system and a filterscope system revealed that the primary erosion zone was correlated with the high heat flux regions on the limiter. This analysis matched to where the erosion zone was found in the post-mortem analysis, which was done with scanning electron microscopy/focused ion beam/electron dispersive x-ray spectroscopy imaging. Additionally, a region of prompt deposition was found to the inside of these high heat flux zones. A region of far scrape-off layer (SOL) deposition was found at the edges of the limiter tiles. All deposition regions were identified by their homogeneous, increased oxygen content compared to the pure carbon makeup of the limiters. Poloidal variation of the impinging heat flux follow the imprint of the 3D SOL flux tubes. In how far this reflects in the PSI will require further analysis and modeling.

  4. Experimental and numerical modelling of surface water-groundwater flow and pollution interactions under tidal forcing

    Science.gov (United States)

    Spanoudaki, Katerina; Bockelmann-Evans, Bettina; Schaefer, Florian; Kampanis, Nikolaos; Nanou-Giannarou, Aikaterini; Stamou, Anastasios; Falconer, Roger

    2015-04-01

    Surface water and groundwater are integral components of the hydrologic continuum and the interaction between them affects both their quantity and quality. However, surface water and groundwater are often considered as two separate systems and are analysed independently. This separation is partly due to the different time scales, which apply in surface water and groundwater flows and partly due to the difficulties in measuring and modelling their interactions (Winter et al., 1998). Coastal areas in particular are a difficult hydrologic environment to represent with a mathematical model due to the large number of contributing hydrologic processes. Accurate prediction of interactions between coastal waters, groundwater and neighbouring wetlands, for example, requires the use of integrated surface water-groundwater models. In the past few decades a large number of mathematical models and field methods have been developed in order to quantify the interaction between groundwater and hydraulically connected surface water bodies. Field studies may provide the best data (Hughes, 1995) but are usually expensive and involve too many parameters. In addition, the interpretation of field measurements and linking with modelling tools often proves to be difficult. In contrast, experimental studies are less expensive and provide controlled data. However, experimental studies of surface water-groundwater interaction are less frequently encountered in the literature than filed studies (e.g. Ebrahimi et al., 2007; Kuan et al., 2012; Sparks et al., 2013). To this end, an experimental model has been constructed at the Hyder Hydraulics Laboratory at Cardiff University to enable measurements to be made of groundwater transport through a sand embankment between a tidal water body such as an estuary and a non-tidal water body such as a wetland. The transport behaviour of a conservative tracer was studied for a constant water level on the wetland side of the embankment, while running a

  5. Ozone-surface interactions: Investigations of mechanisms, kinetics, mass transport, and implications for indoor air quality

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, Glenn Charles [Univ. of California, Berkeley, CA (United States)

    1999-12-01

    In this dissertation, results are presented of laboratory investigations and mathematical modeling efforts designed to better understand the interactions of ozone with surfaces. In the laboratory, carpet and duct materials were exposed to ozone and measured ozone uptake kinetics and the ozone induced emissions of volatile organic compounds. To understand the results of the experiments, mathematical methods were developed to describe dynamic indoor aldehyde concentrations, mass transport of reactive species to smooth surfaces, the equivalent reaction probability of whole carpet due to the surface reactivity of fibers and carpet backing, and ozone aging of surfaces. Carpets, separated carpet fibers, and separated carpet backing all tended to release aldehydes when exposed to ozone. Secondary emissions were mostly n-nonanal and several other smaller aldehydes. The pattern of emissions suggested that vegetable oils may be precursors for these oxidized emissions. Several possible precursors and experiments in which linseed and tung oils were tested for their secondary emission potential were discussed. Dynamic emission rates of 2-nonenal from a residential carpet may indicate that intermediate species in the oxidation of conjugated olefins can significantly delay aldehyde emissions and act as reservoir for these compounds. The ozone induced emission rate of 2-nonenal, a very odorous compound, can result in odorous indoor concentrations for several years. Surface ozone reactivity is a key parameter in determining the flux of ozone to a surface, is parameterized by the reaction probability, which is simply the probability that an ozone molecule will be irreversibly consumed when it strikes a surface. In laboratory studies of two residential and two commercial carpets, the ozone reaction probability for carpet fibers, carpet backing and the equivalent reaction probability for whole carpet were determined. Typically reaction probability values for these materials were 10

  6. Workplace Charging. Charging Up University Campuses

    Energy Technology Data Exchange (ETDEWEB)

    Giles, Carrie [ICF International, Fairfax, VA (United States); Ryder, Carrie [ICF International, Fairfax, VA (United States); Lommele, Stephen [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-03-01

    This case study features the experiences of university partners in the U.S. Department of Energy's (DOE) Workplace Charging Challenge with the installation and management of plug-in electric vehicle (PEV) charging stations.

  7. Interactions between whey protein isolate and gum Arabic.

    Science.gov (United States)

    Klein, Miri; Aserin, Abraham; Ben Ishai, Paul; Garti, Nissim

    2010-09-01

    In this study we have attempted to understand the nature of "charge interactions" between two negatively charged biopolymers (whey protein isolate, WPI and gum Arabic, GA) and, consequently, why their mixture exhibits better interfacial activity. Surface tension (gamma(0)) measurements indicated that at ca. 1 wt.% of the biopolymer mixture (3:1 wt. ratio) the air/water surface is saturated. At 5 wt.% the gamma(0) of the mixture is lower than the calculated co-operative value. The zeta-potential measurements revealed that the isoelectric point of the WPI:GA 3:1 wt. ratio mixture is 3.8. The zeta-potential values up to pH 6 are below those calculated. Similarly, the electrical conductivities of the mixture are lower than those calculated. All these measurements indicate: (1) partial charge neutralization in spite of the fact that both biopolymers are negative or (2) partial charge-charge interactions between the two biopolymers. The thermal heating behavior of the frozen water in the aqueous mixture studied by DSC (heating cycle of the frozen sample) clearly indicates that the two biopolymers are interacting. We calculated the enthalpy, the free energy and the chemical potential of the interactions. We found that the interactions of the biopolymers are rather weak. They are likely derived from some local positively charged domains (pH 7) on the protein that neutralize some of the negatively charged GA. These interactions form weak charge adducts. These charge adducts are sufficient to improve its adsorption into the oil-water interface and enhance the emulsion stability. Copyright 2010 Elsevier B.V. All rights reserved.

  8. Interaction of Model Inhibitor Compounds with Minimalist Cluster Representations of Hydroxyl Terminated Metal Oxide Surfaces

    Directory of Open Access Journals (Sweden)

    Christopher D. Taylor

    2018-01-01

    Full Text Available The computational modeling of corrosion inhibitors at the level of molecular interactions has been pursued for decades, and recent developments are allowing increasingly realistic models to be developed for inhibitor–inhibitor, inhibitor–solvent and inhibitor–metal interactions. At the same time, there remains a need for simplistic models to be used for the purpose of screening molecules for proposed inhibitor performance. Herein, we apply a reductionist model for metal surfaces consisting of a metal cation with hydroxide ligands and use quantum chemical modeling to approximate the free energy of adsorption for several imidazoline class candidate corrosion inhibitors. The approximation is made using the binding energy and the partition coefficient. As in some previous work, we consider different methods for incorporating solvent and reference systems for the partition coefficient. We compare the findings from this short study with some previous theoretical work on similar systems. The binding energies for the inhibitors to the metal hydroxide clusters are found to be intermediate to the binding energies calculated in other work for bare metal vs. metal oxide surfaces. The method is applied to copper, iron, aluminum and nickel metal systems.

  9. Proper construction of ab initio global potential surfaces with accurate long-range interactions

    International Nuclear Information System (INIS)

    Ho, Tak-San; Rabitz, Herschel

    2000-01-01

    An efficient procedure based on the reproducing kernel Hilbert space interpolation method is presented for constructing intermolecular potential energy surfaces (PES) using not only calculated ab initio data but also a priori information on long-range interactions. Explicitly, use of the reciprocal power reproducing kernel on the semiinfinite interval [0,∞) yields a set of exact linear relations between dispersion (multipolar) coefficients and PES data points at finite internuclear separations. Consequently, given a combined set of ab initio data and the values of dispersion (multipolar) coefficients, the potential interpolation problem subject to long-range interaction constraints can be solved to render globally smooth, asymptotically accurate ab initio potential energy surfaces. Very good results have been obtained for the one-dimensional He-He potential curve and the two-dimensional Ne-CO PES. The construction of the Ne-CO PES was facilitated by invoking a new reproducing kernel for the angular coordinate based on the optimally stable and shape-preserving Bernstein basis functions. (c) 2000 American Institute of Physics

  10. c-Met and Other Cell Surface Molecules: Interaction, Activation and Functional Consequences

    Directory of Open Access Journals (Sweden)

    Giuditta Viticchiè

    2015-01-01

    Full Text Available The c-Met receptor, also known as the HGF receptor, is one of the most studied tyrosine kinase receptors, yet its biological functions and activation mechanisms are still not fully understood. c-Met has been implicated in embryonic development and organogenesis, in tissue remodelling homeostasis and repair and in cancer metastasis. These functions are indicative of the many cellular processes in which the receptor plays a role, including cell motility, scattering, survival and proliferation. In the context of malignancy, sustained activation of c-Met leads to a signalling cascade involving a multitude of kinases that initiate an invasive and metastatic program. Many proteins can affect the activation of c-Met, including a variety of other cell surface and membrane-spanning molecules or receptors. Some cell surface molecules share structural homology with the c-Met extracellular domain and can activate c-Met via clustering through this domain (e.g., plexins, whereas other receptor tyrosine kinases can enhance c-Met activation and signalling through intracellular signalling cascades (e.g., EGFR. In this review, we provide an overview of c-Met interactions and crosstalk with partner molecules and the functional consequences of these interactions on c-Met activation and downstream signalling, c-Met intracellular localization/recycling and c-Met degradation.

  11. Surface and micellar properties of Chloroquine Diphosphate and its interactions with surfactants and Human Serum Albumin

    International Nuclear Information System (INIS)

    Usman, Muhammad; Siddiq, Mohammad

    2013-01-01

    Highlights: ► Free energy of adsorption is more negative than free energy of micellization. ► Shifts in UV/Visible spectra in presence of SDS indicated interaction of CLQ with SDS. ► The decrease in fluorescence intensity of HSA by CLQ shows its binding with HSA. -- Abstract: This manuscript addresses the physicochemical behavior of an antimalarial drug Chloroquine Diphosphate (CLQ) as well as its interaction with anionic surfactants and Human Serum Albumin (HSA). Surface tension and specific conductivity were employed to detect the critical micelle concentration (CMC) and thus its surface and thermodynamic parameters were calculated. Solubilization of this drug within micelles of anionic surfactant sodium dodecyl sulfate (SDS) has also been studied. UV/Visible spectroscopy was used to calculate partition coefficient (K x ), free energy of partition and number of drug molecules per micelle. The complexation of drug with HSA at physiological conditions (pH 7.4) has also been analyzed by using UV/Visible and fluorescence spectroscopy. The values of drug-protein binding constant, number of binding sites and free energy of binding were calculated

  12. Interaction of multi-walled carbon nanotubes with perfluorinated sulfonic acid ionomers and surface treatment studies

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma; Dhiman, Rajnish; Borghei, Maryam

    2014-01-01

    The interaction between high surface area nano-carbon catalyst supports for proton exchange membrane fuel cells (PEMFCs) and perfluorinated sulfonic acid (Nafion®) ionomer was studied 19 fluorine nuclear magnetic resonance spectroscopy (19F-NMR). The method was developed and improved for more eff....... The results will contribute to optimize electrode preparation with novel nano-carbon catalyst supports and durable catalyst for low temperature (LT) PEMFCs.......The interaction between high surface area nano-carbon catalyst supports for proton exchange membrane fuel cells (PEMFCs) and perfluorinated sulfonic acid (Nafion®) ionomer was studied 19 fluorine nuclear magnetic resonance spectroscopy (19F-NMR). The method was developed and improved for more...... efficient, user-friendly and systematic studies based on our earlier experience. In this work, multi-walled carbon nanotubes (MWCNTs) from Showa Denko® and the corresponding acid modified products were explored. The adsorption at low concentration was found to follow a Langmuir isotherm. Adsorption...

  13. Effect of surface functionalisation on the interaction of iron oxide nanoparticles with polymerase chain reaction.

    Science.gov (United States)

    Aysan, Ayse Beyza; Knejzlík, Zdeněk; Ulbrich, Pavel; Šoltys, Marek; Zadražil, Aleš; Štěpánek, František

    2017-05-01

    The combination of nanoparticles with the polymerase chain reaction (PCR) can have benefits such as easier sample handling or higher sensitivity, but also drawbacks such as loss of colloidal stability or inhibition of the PCR. The present work systematically investigates the interaction of magnetic iron oxide nanoparticles (MIONs) with the PCR in terms of colloidal stability and potential PCR inhibition due to interaction between the PCR components and the nanoparticle surface. Several types of MIONs with and without surface functionalisation by sodium citrate, dextran and 3-aminopropyl-triethoxysilane (APTES) were prepared and characterised by Transmission Electron Microscopy (TEM), dynamic light scattering (DLS) and Fourier Transform Infrared (FT-IR) spectroscopy. Colloidal stability in the presence of the PCR components was investigated both at room temperature and under PCR thermo-cycling. Dextran-stabilized MIONs show the best colloidal stability in the PCR mix at both room and elevated temperatures. Citrate- and APTES-stabilised as well as uncoated MIONs show a comparable PCR inhibition near the concentration 0.1mgml -1 while the inhibition of dextran stabilized MIONs became apparent near 0.5mgml -1 . It was demonstrated that the PCR could be effectively carried out even in the presence of elevated concentration of MIONs up to 2mgml -1 by choosing the right coating approach and supplementing the reaction mix by critical components, Taq DNA polymerase and Mg 2+ ions. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Prediction of protein retention times in hydrophobic interaction chromatography by robust statistical characterization of their atomic-level surface properties.

    NARCIS (Netherlands)

    Hanke, A.T.; Klijn, M.E.; Verhaert, P.D.; Wielen, van der L.; Ottens, M.; Eppink, M.H.M.; Sandt, van de E.J.A.X.

    2016-01-01

    The correlation between the dimensionless retention times (DRT) of proteins in hydrophobic interaction chromatography (HIC) and their surface properties were investigated. A ternary atomic-level hydrophobicity scale was used to calculate the distribution of local average hydrophobicity across the

  15. Studies on the interaction between nanodiamond and human hemoglobin by surface tension measurement and spectroscopy methods.

    Science.gov (United States)

    Pishkar, Leila; Taheri, Saba; Makarem, Somayeh; Alizadeh Zeinabad, Hojjat; Rahimi, Arash; Saboury, Ali Akbar; Falahati, Mojtaba

    2017-02-01

    In this study, a novel method to probe molecular interactions and binding of human hemoglobin (Hb) with nanodiamond (ND) was introduced based on the surface tension measurement. This method complements conventional techniques, which are basically done by zeta potential and dynamic light scattering (DLS) measurements, near and far circular dichroism (CD) spectroscopy, intrinsic and extrinsic fluorescence spectroscopy. Addition of ND to Hb solution increased the surface tension value of Hb-ND complex relative to those of Hb and ND molecules. The zeta potential values reveled that Hb and ND provide identical charge distribution at pH 7.5. DLS measurements demonstrated that Hb, ND, and ND-Hb complex have hydrodynamic radiuses of 98.37 ± 4.57, 122.07 ± 7.88 nm and 62.27 ± 3.70 at pH of 7.5 respectively. Far and near UV-CD results indicated the loss of α-helix structure and conformational changes of Hb, respectively. Intrinsic fluorescence data demonstrated that the fluorescence quenching of Hb by ND was the result of the static quenching. The hydrophobic interaction plays a pivotal role in the interaction of ND with Hb. Fluorescence intensity changes over time revealed conformational change of Hb continues after the mixing of the components (Hb-ND) till 15 min, which is indicative of the denaturation of the Hb relative to the protein control. Extrinsic fluorescence data showed a considerable enhancement of the ANS fluorescence intensity of Hb-ND system relative to the Hb till 60 nM of ND, likely persuaded by greater exposure of nonpolar residues of Hb hydrophobic pocket. The remarkable decrease in T m value of Hb in Hb-ND complex exhibits interaction of Hb with ND conducts to conformational changes of Hb. This study offers consequential discrimination into the interaction of ND with proteins, which may be of significance for further appeal of these nanoparticles in biotechnology prosecution.

  16. Characterizing groundwater/surface-water interactions in the interior of Jianghan Plain, central China

    Science.gov (United States)

    Du, Yao; Ma, Teng; Deng, Yamin; Shen, Shuai; Lu, Zongjie

    2018-01-01

    Quantifying groundwater/surface-water interactions is essential for managing water resources and revealing contaminant fate. There has been little concern on the exchange between streams and aquifers through an extensive aquitard thus far. In this study, hydrogeologic calculation and tritium modeling were jointly applied to characterize such interactions through an extensive aquitard in the interior of Jianghan Plain, an alluvial plain of Yangtze River, China. One groundwater simulation suggested that the lateral distance of influence from the river was about 1,000 m; vertical flow in the aquitard followed by lateral flow in the aquifer contributed significantly more ( 90%) to the aquifer head change near the river than lateral bank storage in the aquitard followed by infiltration. The hydrogeologic calculation produced vertical fluxes of the order 0.01 m/day both near and farther from the river, suggesting that similar shorter-lived (half-monthly) vertical fluxes occur between the river and aquitard near the river, and between the surface end members and aquitard farther from the river. Tritium simulation based on the OTIS model produced an average groundwater residence time of about 15 years near the river and a resulting vertical flux of the order 0.001 m/day. Another tritium simulation based on a dispersion model produced a vertical flux of the order 0.0001 m/day away from the river, coupled with an average residence time of around 90 years. These results suggest an order of magnitude difference for the longer-lived (decadal) vertical fluxes between surface waters and the aquifer near and away from the river.

  17. Probing Water and CO2 Interactions at the Surface of Collapsed Titania Nanotubes Using IR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Kaustava Bhattacharyya

    2015-08-01

    Full Text Available Collapsed titania nanotubes (cTiNT were synthesized by the calcination of titania nanotubes (TiNT at 650 °C, which leads to a collapse of their tubular morphology, a substantial reduction in surface area, and a partial transformation of anatase to the rutile phase. There are no significant changes in the position of the XPS responses for Ti and O on oxidation or reduction of the cTiNTs, but the responses are more symmetric than those observed for TiNTs, indicating fewer surface defects and no change in the oxidation state of titanium on oxidative and/or reductive pretreatment. The interaction of H2O and CO2 with the cTiNT surface was studied. The region corresponding to OH stretching absorptions extends below 3000 cm−1, and thus is broader than is typically observed for absorptions of the OH stretches of water. The exchange of protons for deuterons on exposure to D2O leads to a depletion of this extended absorption and the appearance of new absorptions, which are compatible with deuterium exchange. We discuss the source of this extended low frequency OH stretching region and conclude that it is likely due to the hydrogen-bonded OH stretches. Interaction of the reduced cTiNTs with CO2 leads to a similar but smaller set of adsorbed carbonates and bicarbonates as reported for reduced TiNTs before collapse. Implications of these observations and the presence of proton sources leading to hydrogen bonding are discussed relative to potential chemical and photochemical activity of the TiNTs. These results point to the critical influence of defect structure on CO2 photoconversion.

  18. Interacting with the biomolecular solvent accessible surface via a haptic feedback device

    Directory of Open Access Journals (Sweden)

    Hayward Steven

    2009-10-01

    Full Text Available Abstract Background From the 1950s computer based renderings of molecules have been produced to aid researchers in their understanding of biomolecular structure and function. A major consideration for any molecular graphics software is the ability to visualise the three dimensional structure of the molecule. Traditionally, this was accomplished via stereoscopic pairs of images and later realised with three dimensional display technologies. Using a haptic feedback device in combination with molecular graphics has the potential to enhance three dimensional visualisation. Although haptic feedback devices have been used to feel the interaction forces during molecular docking they have not been used explicitly as an aid to visualisation. Results A haptic rendering application for biomolecular visualisation has been developed that allows the user to gain three-dimensional awareness of the shape of a biomolecule. By using a water molecule as the probe, modelled as an oxygen atom having hard-sphere interactions with the biomolecule, the process of exploration has the further benefit of being able to determine regions on the molecular surface that are accessible to the solvent. This gives insight into how awkward it is for a water molecule to gain access to or escape from channels and cavities, indicating possible entropic bottlenecks. In the case of liver alcohol dehydrogenase bound to the inhibitor SAD, it was found that there is a channel just wide enough for a single water molecule to pass through. Placing the probe coincident with crystallographic water molecules suggests that they are sometimes located within small pockets that provide a sterically stable environment irrespective of hydrogen bonding considerations. Conclusion By using the software, named HaptiMol ISAS (available from http://www.haptimol.co.uk, one can explore the accessible surface of biomolecules using a three-dimensional input device to gain insights into the shape and water

  19. Characterization of the Interactions between Titanium Dioxide Nanoparticles and Polymethoxyflavones Using Surface-Enhanced Raman Spectroscopy.

    Science.gov (United States)

    Cao, Xiaoqiong; Ma, Changchu; Gao, Zili; Zheng, Jinkai; He, Lili; McClements, David Julian; Xiao, Hang

    2016-12-14

    Nanosized titanium dioxide (TiO 2 ) particles are commonly present in TiO 2 food additives (E171) and have been associated with potential adverse effects on health. However, little knowledge is available regarding the interactions between TiO 2 nanoparticles (NPs) and other food components, such as flavonoids. In this study, we aim to study the molecular interactions between TiO 2 anatase NPs and three structurally closely related polymethoxyflavones (PMFs, flavonoids found in citrus fruits), namely, 3',4'-didemethylnobiletin (DDN), 5-demethylnobiletin (5DN), and 5,3',4'-tridemethylnobiletin (TDN), using ultraviolet-visible (UV-vis) spectrometry and surface-enhanced Raman spectroscopy (SERS). In the UV-vis absorption spectra, bathochromic effects were observed after DDN and TDN conjugated with TiO 2 NPs. The results from SERS analysis clearly demonstrated that DDN and TDN could bind TiO 2 NPs with the functional groups 3'-OH and 4'-OH on ring B and formed charge-transfer complexes. However, 5DN with functional groups C═O on ring C and 5-OH on ring A could not bind TiO 2 NPs. Knowledge on the molecular interactions between TiO 2 NPs and food components, such as flavonoids, will facilitate the understanding of the fate of TiO 2 NPs during food processing and in the gastrointestinal tract after oral consumption.

  20. Interactions between nitrogen molecules and barium atoms on Ru (0001) surface

    International Nuclear Information System (INIS)

    Zhao Xinxin; Mi Yiming; Xu Hongxia; Wang Lili; Ren Li; Tao Xiangming; Tan Mingqiu

    2011-01-01

    We had performed first principles calculations on interactions between nitrogen molecules and barium atoms on Ru (0001) surface using density function theory methods. It was shown that effects of barium atoms weakened the bond strength of nitrogen molecules. The bond length of nitrogen molecule increases from 0.113 nm on Ru (001)-N 2 to 0.120 nm on Ru (001)-N 2 /Ba surface. While stretch vibrational frequency of nitrogen molecule decreased from 2222 cm -1 and charge transfer toward nitrogen molecule increased from 0.3 e to 1.1 e. Charge was mainly translated from 6 s orbitals of barium atoms to 4 d orbitals of substrate, which enhanced the hybridization between 4 d and 2 π orbitals and increased the dipole moment of 5 σ and d π orbitals of nitrogen molecule. The molecular dipole moment of nitrogen molecule was increased by -0.136 e Anstrom. It was suggested that barium had some characters to be an electronic promoter on the process of activating nitrogen molecules on Ru (0001) surface. (authors)

  1. SIPSON--simulation of interaction between pipe flow and surface overland flow in networks.

    Science.gov (United States)

    Djordjević, S; Prodanović, D; Maksimović, C; Ivetić, M; Savić, D

    2005-01-01

    The new simulation model, named SIPSON, based on the Preissmann finite difference method and the conjugate gradient method, is presented in the paper. This model simulates conditions when the hydraulic capacity of a sewer system is exceeded, pipe flow is pressurized, the water flows out from the piped system to the streets, and the inlets cannot capture all the runoff. In the mathematical model, buried structures and pipelines, together with surface channels, make a horizontally and vertically looped network involving a complex interaction of flows. In this paper, special internal boundary conditions related to equivalent inlets are discussed. Procedures are described for the simulation of manhole cover loss, basement flooding, the representation of street geometry, and the distribution of runoff hydrographs between surface and underground networks. All these procedures are built into the simulation model. Relevant issues are illustrated on a set of examples, focusing on specific parameters and comparison with field measurements of flooding of the Motilal ki Chal catchment (Indore, India). Satisfactory agreement of observed and simulated hydrographs and maximum surface flooding levels is obtained. It is concluded that the presented approach is an improvement compared to the standard "virtual reservoir" approach commonly applied in most of the models.

  2. The interaction between fluid flow and ultra-hydrophobic surface in mini channel

    Directory of Open Access Journals (Sweden)

    Jasikova Darina

    2017-01-01

    Full Text Available Interaction of liquid with ultra-hydrophobic surface is accompanied by creation of layer of air. The effect of the air film has a potential of use in industry in many applications. The quality of the surface is influenced by matrix roughness, the character of physical or chemical cover. There was developed a method for analysis of the liquid flow and the air film using the lighting in volume, visualization with CCD camera and long distance microscope, and optical filters. There were prepared four stainless steel samples of inner channel of dimensions (80 × 8 × 8 mm and initial surface roughness Ra 0.33, Ra 1.0, Ra 2.0, and Ra 2.2. The inner channel was treated with plasma and commercial hydrophobic coating Greblon (WEILBURGER Coatings GmbH. There was realized study focused on the liquid flow velocity profile close to the air film. There are present results for laminar, transient and turbulent flows. The study also estimated the air film thickness depending on the Re number. The knowledge of the air film behaviour helps applied suitable degree of processing and cover for the target application.

  3. Nonperturbative effects and indirect exchange interaction between quantum impurities on metallic (111) surfaces

    Science.gov (United States)

    Allerdt, A.; Žitko, R.; Feiguin, A. E.

    2017-06-01

    The (111) surface of noble metals is usually treated as an isolated two-dimensional (2D) triangular lattice completely decoupled from the bulk. However, unlike in topological insulators, bulk bands also cross the Fermi level. We here introduce an effective tight-binding model that accurately reproduces results from first-principles calculations, accounting for both surface and bulk states. We numerically solve the many-body problem of two quantum impurities sitting on the surface by means of the density matrix renormalization group. By performing simulations in a star geometry, we are able to study the nonperturbative problem in the thermodynamic limit with machine precision accuracy. We find that there is a nontrivial competition between Kondo and RKKY physics and as a consequence, ferromagnetism is never developed, except at short distances. The bulk introduces a variation in the period of the RKKY interactions, and therefore the problem departs considerably from the simpler 2D case. In addition, screening and the magnitude of the effective indirect exchange are enhanced by the contributions from the bulk states.

  4. Acidic Microenvironments in Waste Rock Characterized by Neutral Drainage: Bacteria–Mineral Interactions at Sulfide Surfaces

    Directory of Open Access Journals (Sweden)

    John W. Dockrey

    2014-03-01

    Full Text Available Microbial populations and microbe-mineral interactions were examined in waste rock characterized by neutral rock drainage (NRD. Samples of three primary sulfide-bearing waste rock types (i.e., marble-hornfels, intrusive, exoskarn were collected from field-scale experiments at the Antamina Cu–Zn–Mo mine, Peru. Microbial communities within all samples were dominated by neutrophilic thiosulfate oxidizing bacteria. However, acidophilic iron and sulfur oxidizers were present within intrusive waste rock characterized by bulk circumneutral pH drainage. The extensive development of microbially colonized porous Fe(III (oxyhydroxide and Fe(III (oxyhydroxysulfate precipitates was observed at sulfide-mineral surfaces during examination by field emission-scanning electron microscopy-energy dispersive X-ray spectroscopy (FE-SEM-EDS. Linear combination fitting of bulk extended X-ray absorption fine structure (EXAFS spectra for these precipitates indicated they were composed of schwertmannite [Fe8O8(OH6–4.5(SO41–1.75], lepidocrocite [γ-FeO(OH] and K-jarosite [KFe3(OH6(SO42]. The presence of schwertmannite and K-jarosite is indicative of the development of localized acidic microenvironments at sulfide-mineral surfaces. Extensive bacterial colonization of this porous layer and pitting of underlying sulfide-mineral surfaces suggests that acidic microenvironments can play an important role in sulfide-mineral oxidation under bulk circumneutral pH conditions. These findings have important implications for water quality management in NRD settings.

  5. 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.

  6. Thermodynamic Stability of Actinide-Dioxide Solid Solutions and Surface Interactions with Water

    Science.gov (United States)

    Asta, Mark

    2012-02-01

    Fluorite-structured actinide dioxides are the most common forms of fuel used in nuclear energy production worldwide. This talk will provide an overview of insights into the energetics of these compounds derived through the combination of density-functional-theory-based computational studies (including Hubbard-U corrections) and calorimetric measurements. The talk will focus on two main topics: the mixing energetics of cation solid solutions, and the energetics of water adsorption on the surfaces of these compounds. For the first topic, we present results for ThO2 and UO2 based solid solutions, highlighting the roles of elastic energy arising from cation size mismatch, electrostatic interactions, and charge-transfer reactions, in governing the sign and magnitude of the mixing energetics. For water adsorption, we contrast results for surface and adsorption energies on two fluorite-structured compounds, ThO2 and CeO2, that are relevant for understanding the behavior of water on actinide oxide surfaces more generally. Through a comparison between calorimetric measurements and computational results we assess the level of accuracy achieved in the computational modeling, and suggest areas where further experimental studies would be particularly useful.

  7. Modeling the interaction of nanoparticles with mineral surfaces: adsorbed C60 on pyrophyllite.

    Science.gov (United States)

    Zhu, Runliang; Molinari, Marco; Shapley, Thomas V; Parker, Stephen C

    2013-08-01

    We have applied DFT and molecular modeling to investigate the interaction between carbon-based nanoparticles (CNPs) and geosorbents using the adsorption of buckminsterfullerene (C60) on pyrophyllite and comparing it to the aggregation of C60 molecules. The approach is transferable and can be readily applied to more complex CNP-clay systems. We predict that C60 molecules adsorb preferably on the mineral surface and that the most stable adsorption site is the ditrigonal cavity of the surface. The free energy of adsorption on pyrophyllite was calculated to be more favorable than aggregation both in a vacuum (-0.47 vs -0.41 eV) and in water (-0.25 vs -0.19 eV). In aqueous environments, there are energy barriers as the C60 molecule approaches either a surface or another C60 molecule, and these occur upon disruption of the hydration layers that surround each component. There are also free energy minima that correspond to outer-sphere and more favorable inner-sphere complexes. We expect this adsorptive behavior to be a general feature of CNP-clay systems, and as clays are ubiquitous in the environment, it will offer an inexpensive remediative method to prevent the widespread impact of molecular C60 and CNPs.

  8. Influence of irradiation conditions on plasma evolution in laser-surface interaction

    Science.gov (United States)

    Hermann, J.; Boulmer-Leborgne, C.; Dubreuil, B.; Mihailescu, I. N.

    1993-09-01

    The plasma plume induced by pulsed CO2 laser irradiation of a Ti target at power densities up to 4×108 W cm-2 was studied by emission spectroscopy. Time- and space-resolved measurements were performed by varying laser intensity, laser temporal pulse shape, ambient gas pressure, and the nature of the ambient gas. Experimental results are discussed by comparison with usual models. We show that shock wave and plasma propagation depend critically on the ratio Ivap/Ii, Ivap being the intensity threshold for surface vaporization and Ii the plasma ignition threshold of the ambient gas. Spectroscopic diagnostics of the helium breakdown plasma show maximum values of electron temperature and electron density in the order of kTe˜10 eV and ne=1018 cm-3, respectively. The plasma cannot be described by local thermodynamic equilibrium modeling. Nevertheless, excited metal atoms appear to be in equilibrium with electrons, hence, they can be used like a probe to measure the electron temperature. In order to get information on the role of the plasma in the laser-surface interaction, Ti surfaces were investigated by microscopy after irradiation. Thus an enhanced momentum transfer from the plasma to the target due to the recoil pressure of the breakdown plasma could be evidenced.

  9. The Structure of a Hypersonic Air Flow near a Plane Surface at Various Intensities of Magnetogasdynamic Interaction

    Science.gov (United States)

    Fomichev, V. P.; Yadrenkin, M. A.

    2017-12-01

    This Letter presents a systematization of the effects observed in experiments on the magnetogasdynamic interaction near the surface of a plate in a high-speed gas flow. Ranges of the hydromagnetic-interaction parameter determining various levels of influence on the shock-wave structure of the flow are established.

  10. Mechanisms and regulation of surface interactions and biofilm formation in Agrobacterium

    Science.gov (United States)

    Heindl, Jason E.; Wang, Yi; Heckel, Brynn C.; Mohari, Bitan; Feirer, Nathan; Fuqua, Clay

    2014-01-01

    For many pathogenic bacteria surface attachment is a required first step during host interactions. Attachment can proceed to invasion of host tissue or cells or to establishment of a multicellular bacterial community known as a biofilm. The transition from a unicellular, often motile, state to a sessile, multicellular, biofilm-associated state is one of the most important developmental decisions for bacteria. Agrobacterium tumefaciens genetically transforms plant cells by transfer and integration of a segment of plasmid-encoded transferred DNA (T-DNA) into the host genome, and has also been a valuable tool for plant geneticists. A. tumefaciens attaches to and forms a complex biofilm on a variety of biotic and abiotic substrates in vitro. Although rarely studied in situ, it is hypothesized that the biofilm state plays an important functional role in the ecology of this organism. Surface attachment, motility, and cell division are coordinated through a complex regulatory network that imparts an unexpected asymmetry to the A. tumefaciens life cycle. In this review, we describe the mechanisms by which A. tumefaciens associates with surfaces, and regulation of this process. We focus on the transition between flagellar-based motility and surface attachment, and on the composition, production, and secretion of multiple extracellular components that contribute to the biofilm matrix. Biofilm formation by A. tumefaciens is linked with virulence both mechanistically and through shared regulatory molecules. We detail our current understanding of these and other regulatory schemes, as well as the internal and external (environmental) cues mediating development of the biofilm state, including the second messenger cyclic-di-GMP, nutrient levels, and the role of the plant host in influencing attachment and biofilm formation. A. tumefaciens is an important model system contributing to our understanding of developmental transitions, bacterial cell biology, and biofilm formation

  11. Mechanisms and Regulation of Surface Interactions and Biofilm Formation in Agrobacterium

    Directory of Open Access Journals (Sweden)

    Jason E. Heindl

    2014-05-01

    Full Text Available For many pathogenic bacteria surface attachment is a required first step during host interactions. Attachment can proceed to invasion of host tissue or cells or to establishment of a multicellular bacterial community known as a biofilm. The transition from a unicellular, often motile, state to a sessile, multicellular, biofilm-associated state is one of the most important developmental decisions for bacteria. Agrobacterium tumefaciens genetically transforms plant cells by transfer and integration of a segment of plasmid-encoded transferred DNA (T-DNA into the host genome, and has also been a valuable tool for plant geneticists. A. tumefaciens attaches to and forms a complex biofilm on a variety of biotic and abiotic substrates in vitro. Although rarely studied in situ, it is hypothesized that the biofilm state plays an important functional role in the ecology of this organism. Surface attachment, motility, and cell division are coordinated through a complex regulatory network that imparts an unexpected asymmetry to the A. tumefaciens life cycle. In this review we describe the mechanisms by which A. tumefaciens associates with surfaces, and regulation of this process. We focus on the transition between flagellar-based motility and surface attachment, and on the composition, production, and secretion of multiple extracellular components that contribute to the biofilm matrix. Biofilm formation by A. tumefaciens is linked with virulence both mechanistically and through shared regulatory molecules. We detail our current understanding of these and other regulatory schemes, as well as the internal and external (environmental cues mediating development of the biofilm state, including the second messenger cyclic-di-GMP, nutrient levels, and the role of the plant host in influencing attachment and biofilm formation. A. tumefaciens is an important model system contributing to our understanding of developmental transitions, bacterial cell biology, and

  12. Protein-protein interactions in paralogues: Electrostatics modulates specificity on a conserved steric scaffold.

    Science.gov (United States)

    Ivanov, Stefan M; Cawley, Andrew; Huber, Roland G; Bond, Peter J; Warwicker, Jim

    2017-01-01

    An improved knowledge of protein-protein interactions is essential for better understanding of metabolic and signaling networks, and cellular function. Progress tends to be based on structure determination and predictions using known structures, along with computational methods based on evolutionary information or detailed atomistic descriptions. We hypothesized that for the case of interactions across a common interface, between proteins from a pair of paralogue families or within a family of paralogues, a relatively simple interface description could distinguish between binding and non-binding pairs. Using binding data for several systems, and large-scale comparative modeling based on known template complex structures, it is found that charge-charge interactions (for groups bearing net charge) are generally a better discriminant than buried non-polar surface. This is particularly the case for paralogue families that are less divergent, with more reliable comparative modeling. We suggest that electrostatic interactions are major determinants of specificity in such systems, an observation that could be used to predict binding partners.

  13. Protein-protein interactions in paralogues: Electrostatics modulates specificity on a conserved steric scaffold.

    Directory of Open Access Journals (Sweden)

    Stefan M Ivanov

    Full Text Available An improved knowledge of protein-protein interactions is essential for better understanding of metabolic and signaling networks, and cellular function. Progress tends to be based on structure determination and predictions using known structures, along with computational methods based on evolutionary information or detailed atomistic descriptions. We hypothesized that for the case of interactions across a common interface, between proteins from a pair of paralogue families or within a family of paralogues, a relatively simple interface description could distinguish between binding and non-binding pairs. Using binding data for several systems, and large-scale comparative modeling based on known template complex structures, it is found that charge-charge interactions (for groups bearing net charge are generally a better discriminant than buried non-polar surface. This is particularly the case for paralogue families that are less divergent, with more reliable comparative modeling. We suggest that electrostatic interactions are major determinants of specificity in such systems, an observation that could be used to predict binding partners.

  14. Theoretical study of the amphoteric oxide nanoparticle surface charge during multi-particle interactions in aqueous solutions

    Science.gov (United States)

    Alfimov, A. V.; Aryslanova, E. M.; Chivilikhin, S. A.

    2015-11-01

    Nanoparticle surface charge plays an important role in many biological applications. In this study, an analytical surface charging model for the amphoteric oxide nanoparticles has been presented. The model accounts for the particle's electric double layer self-action on the charging process and the charge regulation during multi-particle interactions in aqueous solutions. The employment of the model allows to explicitly describe the nanoparticle agglomeration process and the accompanying agglomerate surface charge variation.

  15. Urban Transit System Microbial Communities Differ by Surface Type and Interaction with Humans and the Environment.

    Science.gov (United States)

    Hsu, Tiffany; Joice, Regina; Vallarino, Jose; Abu-Ali, Galeb; Hartmann, Erica M; Shafquat, Afrah; DuLong, Casey; Baranowski, Catherine; Gevers, Dirk; Green, Jessica L; Morgan, Xochitl C; Spengler, John D; Huttenhower, Curtis

    2016-01-01

    Public transit systems are ideal for studying the urban microbiome and interindividual community transfer. In this study, we used 16S amplicon and shotgun metagenomic sequencing to profile microbial communities on multiple transit surfaces across train lines and stations in the Boston metropolitan transit system. The greatest determinant of microbial community structure was the transit surface type. In contrast, little variation was observed between geographically distinct train lines and stations serving different demographics. All surfaces were dominated by human skin and oral commensals such as Propionibacterium , Corynebacterium , Staphylococcus , and Streptococcus . The detected taxa not associated with humans included generalists from alphaproteobacteria, which were especially abundant on outdoor touchscreens. Shotgun metagenomics further identified viral and eukaryotic microbes, including Propionibacterium phage and Malassezia globosa . Functional profiling showed that Propionibacterium acnes pathways such as propionate production and porphyrin synthesis were enriched on train holding surfaces (holds), while electron transport chain components for aerobic respiration were enriched on touchscreens and seats. Lastly, the transit environment was not found to be a reservoir of antimicrobial resistance and virulence genes. Our results suggest that microbial communities on transit surfaces are maintained from a metapopulation of human skin commensals and environmental generalists, with enrichments corresponding to local interactions with the human body and environmental exposures. IMPORTANCE Mass transit environments, specifically, urban subways, are distinct microbial environments with high occupant densities, diversities, and turnovers, and they are thus especially relevant to public health. Despite this, only three culture-independent subway studies have been performed, all since 2013 and all with widely differing designs and conclusions. In this study, we

  16. Modeling Plant-Atmosphere Interactions and Ramifications on the Surface Energy Balance in Arctic Ecosystems

    Science.gov (United States)

    Linn, R.; Cunningham, P.; Wilson, C. J.

    2011-12-01

    There is broad recognition that the melting of the permafrost in arctic landscapes could have pronounced global climatological impacts. The evolution of the permafrost and its impacts on the carbon and water balances is directly related to balances in the surface energy budget. There are a number of factors that are expected to impact the net heat flux at the surface of the soil including regional atmospheric conditions. However, ultimately this surface energy balance is controlled by local processes including evaporation from the surface, transpiration from vegetation as well as radiative and convective heat transfer. These four processes are directly impacted by coupling between the vegetation and atmosphere, and thus depend heavily upon the horizontal and vertical vegetation structure. If shrubs replace grasses in the arctic ecosystem there will be net shifts in the heat transfer to the ground. For example, the solar radiation that is absorbed by shrubs is separated from the soil by a stem space through which winds blow. In order for the energy to reach the soil it must warm the air and then warm the soil, however some of the warm air is mixed into the atmosphere and diffused. This structural feature can act in a fashion similar to a closed canopy forest, which frequently have cooler temperatures below the canopy than nearby grasslands An atmospheric hydrodynamics model, HIGRAD, has been enhanced to simulate complex, three-dimensional plant-atmosphere interactions at extremely high resolution (~0.1 m in all three directions). The model represents the transport of momentum, heat, moisture, and CO2 and their exchange between the vegetation and surrounding air. HIGRAD was used to simulate coupled atmosphere/vegetation systems representative of heterogeneous shrub and tussock grass surrounding a thermokarst. In these simulations shrubs, uneven grasses, and a thermokarst depression are explicitly resolved, and atmospheric conditions are similar to those of summer

  17. Contact studies of weak adhesive interactions in water with membrane enhanced surface acoustic wave analysis

    Science.gov (United States)

    Brass, David Alan

    The measurement of weak adhesive energies has previously been difficult to obtain. To measure these energies, I designed a technique that uses the combined sensitivities of both a quartz crystal resonator and the inflation of an elastomeric polymer membrane. The surfaces of the quartz crystal and/or the membrane are modified with water swollen polymer brushes, which are used to eliminate nonspecific adhesion. These brushes are then end-modified with adhesive functional groups. An analysis is developed for the frequency response of a quartz crystal resonator as the membrane layer is placed in contact with the surface of these swollen brushes. The shear wave generated at the resonator surface couples into the membrane layer with an efficiency that is strongly dependent on the thickness of the swollen brush layer. The calculated shift decreases substantially for increases in the brush thickness of ten to twenty nanometers, giving a net frequency response that is extremely sensitive to the degree of swelling of the brush. An optimum capping layer thickness is determined by balancing the resonant frequency shift against dissipative effects that weaken the crystal resonance. Detailed calculations are presented for the specific case of poly(ethylene glycol) (PEG) brushes swollen by water and capped by a poly(styrene-ethylene/butene-styrene) (SEBS) elastomeric, water-permeable membrane. These calculations show that the method is sensitive to the properties of the brush layer. This surface acoustic wave technique was coupled with an inflation method that enabled quantification of the adhesion between the membrane and the brush coated surface. This adhesive interaction is obtained from the contact angle made between the quartz and membrane surfaces and the tension on the membrane. An analysis of the membrane profile based on the numerical solution of the axisymmetric Laplace equation is developed and used to investigate both adhesive and non-adhesive situations with both an

  18. Investigation of plasma-surface interaction effects on pulsed electrostatic manipulation for reentry blackout alleviation

    Science.gov (United States)

    Krishnamoorthy, S.; Close, S.

    2017-03-01

    The reentry blackout phenomenon affects most spacecraft entering a dense planetary atmosphere from space, due to the presence of a plasma layer that surrounds the spacecraft. This plasma layer is created by ionization of ambient air due to shock and frictional heating, and in some cases is further enhanced due to contamination by ablation products. This layer causes a strong attenuation of incoming and outgoing electromagnetic waves including those used for command and control, communication and telemetry over a period referred to as the ‘blackout period’. The blackout period may last up to several minutes and is a major contributor to the landing error ellipse at best, and a serious safety hazard in the worst case, especially in the context of human spaceflight. In this work, we present a possible method for alleviation of reentry blackout using electronegative DC pulses applied from insulated electrodes on the reentry vehicle’s surface. We study the reentry plasma’s interaction with a DC pulse using a particle-in-cell (PIC) model. Detailed models of plasma-insulator interaction are included in our simulations. The absorption and scattering of ions and electrons at the plasma-dielectric interface are taken into account. Secondary emission from the insulating surface is also considered, and its implications on various design issues is studied. Furthermore, we explore the effect of changing the applied voltage and the impact of surface physics on the creation and stabilization of communication windows. The primary aim of this analysis is to examine the possibility of restoring L- and S-band communication from the spacecraft to a ground station. Our results provide insight into the effect of key design variables on the response of the plasma to the applied voltage pulse. Simulations show the creation of pockets where electron density in the plasma layer is reduced three orders of magnitude or more in the vicinity of the electrodes. These pockets extend to

  19. Interaction of C2H with molecular hydrogen: Ab initio potential energy surface and scattering calculations

    Science.gov (United States)

    Dagdigian, Paul J.

    2018-01-01

    The potential energy surface (PES) describing the interaction of the ethynyl (C2H) radical in its ground X˜ 2Σ+ electronic state with molecular hydrogen has been computed through restricted coupled cluster calculations including single, double, and (perturbative) triple excitations [RCCSD(T)], with the assumption of fixed molecular geometries. The computed points were fit to an analytical form suitable for time-independent quantum scattering calculations of rotationally inelastic cross sections and rate constants. A representative set of energy dependent state-to-state cross sections is presented and discussed. The PES and cross sections for collisions of H2(j = 0) are compared with a previous study [F. Najar et al., Chem. Phys. Lett. 614, 251 (2014)] of collisions of C2H with H2 treated as a spherical collision partner. Good agreement is found between the two sets of calculations when the H2 molecule in the present calculation is spherically averaged.

  20. How to optimize ultrashort pulse laser interaction with glass surfaces in cutting regimes?

    Energy Technology Data Exchange (ETDEWEB)

    Bulgakova, Nadezhda M., E-mail: bulgakova@fzu.cz [HiLASE Centre, Institute of Physics ASCR, Za Radnicí 828, 25241 Dolní Břežany (Czech Republic); Institute of Thermophysics SB RAS, 1 Lavrentyev Ave., Novosibirsk 630090 (Russian Federation); Zhukov, Vladimir P. [Institute of Computational Technologies SB RAS, 6 Lavrentyev Ave., 630090 Novosibirsk (Russian Federation); Novosibirsk State Technical University, 20 Karl Marx Ave., 630073 Novosibirsk (Russian Federation); Collins, Adam R. [NCLA, NUI Galway, Galway (Ireland); Rostohar, Danijela; Derrien, Thibault J.-Y.; Mocek, Tomáš [HiLASE Centre, Institute of Physics ASCR, Za Radnicí 828, 25241 Dolní Břežany (Czech Republic)

    2015-05-01

    Highlights: • The factors influencing laser micromachining of transparent materials are analyzed. • Important role of ambient gas in laser processing is shown by numerical simulations. • The large potential of bi-wavelength laser processing is demonstrated. - Abstract: The interaction of short and ultrashort pulse laser radiation with glass materials is addressed. Particular attention is paid to regimes which are important in industrial applications such as laser cutting, drilling, functionalization of material surfaces, etc. Different factors influencing the ablation efficiency and quality are summarized and their importance is illustrated experimentally. The effects of ambient gas ionization in front of the irradiated target are also analyzed. A possibility to enhance laser coupling with transparent solids by bi-wavelength irradiation is discussed.

  1. Water quality responses to the interaction between surface water and groundwater along the Songhua River, NE China

    Science.gov (United States)

    Teng, Yanguo; Hu, Bin; Zheng, Jieqiong; Wang, Jinsheng; Zhai, Yuanzheng; Zhu, Chen

    2018-03-01

    Investigation of surface water and groundwater interaction (SW-GW interaction) provides basic information for regional water-resource protection, management, and development. In this survey of a 10-km-wide area along both sides of the Songhua River, northeast China, the hydrogeochemical responses to different SW-GW interactions were studied. Three types of SW-GW interactions were identified—"recharge", "discharge", and "flow-through"—according to the hydraulic connection between the surface water and groundwater. The single factor index, principal component analysis, and hierarchical cluster analysis of the hydrogeochemistry and pollutant data illuminated the hydrogeochemical response to the various SW-GW interactions. Clear SW-GW interactions along the Songhua River were revealed: (1) upstream in the study area, groundwater usually discharges into the surface water, (2) groundwater is recharged by surface water downstream, and (3) discharge and flow-through coexist in between. Statistical analysis indicated that the degree of hydrogeochemical response in different types of hydraulic connection varied, being clear in recharge and flow-through modes, and less obvious in discharge mode. During the interaction process, dilution, adsorption, redox reactions, nitrification, denitrification, and biodegradation contributed to the pollutant concentration and affected hydrogeochemical response in the hyporheic zone.

  2. First-principles study of the interactions of hydrogen with low-index surfaces of PdCu ordered alloy

    Directory of Open Access Journals (Sweden)

    Min Tang

    2017-12-01

    Full Text Available PdCu catalysts play a key role in several hydrogen-involved processes. Among these reactions, the interaction of hydrogen with PdCu essentially determines the catalytic performance. However, the response of PdCu to surrounding hydrogen has been poorly investigated, especially for specific facets of PdCu at different environment. In this work, taking temperature and hydrogen pressure into account, we studied the hydrogen-surface interactions for four low-index surfaces of PdCu through first-principles calculations. It was found that H-PdCu adsorption strong relies on the facets, hydrogen coverage, and reaction environment (temperature and H-pressure. Our work highlights the importance of the environment on the nature of catalyst surfaces and reactions and offers a plausible way to investigate the interactions between gas and the surfaces of nanocatalysts in real reactions.

  3. New Module to Simulate Groundwater-Surface Water Interactions in Small-Scale Alluvial Aquifer System.

    Science.gov (United States)

    Flores, L.

    2017-12-01

    Streamflow depletion can occur when groundwater pumping wells lower water table elevations adjacent to a nearby stream. Being able to accurately model the severity of this process is of critical importance in semi-arid regions where groundwater-surface water interactions affect water rights and the sustainability of water resource practices. The finite-difference flow model MODFLOW is currently the standard for estimating groundwater-surface water interactions in many regions in the western United States. However, certain limitations of the model persist when highly-resolved spatial scales are used to represent the stream-aquifer system, e.g. when the size of computational grid cells is much less than the river width. In this study, an external module is developed and linked with MODFLOW that (1) allows for multiple computational grid cells over the width of the river; (2) computes streamflow and stream stage along the length of the river using the one-dimensional (1D) steady (over a stress period) shallow water equations, which allows for more accurate stream stages when normal flow cannot be assumed or a rating curve is not available; and (3) incorporates a process for computing streamflow loss when an unsaturated zone develops under the streambed. Use of the module not only provides highly-resolved estimates of streamflow depletion, but also of streambed hydraulic conductivity. The new module is applied to the stream-aquifer alluvial system along the South Platte River south of Denver, Colorado, with results tested against field-measured groundwater levels, streamflow, and streamflow depletion.

  4. Quantification of the Pharmacodynamic Interaction of Morphine and Gabapentin Using a Response Surface Approach.

    Science.gov (United States)

    Papathanasiou, Theodoros; Juul, Rasmus Vestergaard; Gabel-Jensen, Charlotte; Kreilgaard, Mads; Heegaard, Anne-Marie; Lund, Trine Meldgaard

    2017-11-01

    The combination of morphine and gabapentin has shown to be promising for managing postoperative pain but finding the right dose for the combination has proven to be a challenge. The purpose of this study was to quantitatively characterize the pharmacodynamic interaction between the two drugs and to identify the optimal concentration-effect relationship of the combination. Information regarding plasma concentrations and von Frey withdrawal thresholds following incisional surgery on Sprague Dawley rats, after administration of morphine, gabapentin, or their combination was available from published studies. The combined pharmacodynamic effect of morphine and gabapentin was analyzed and linked to drug plasma concentrations via a response surface approach using non-linear mixed-effect modeling. Full reversal of withdrawal thresholds for the pain stimulation to presurgery values was estimated at morphine plasma concentration of 435.1 ng/mL. Co-administration of up to 40 μg/mL of gabapentin led to a reduction of the needed morphine concentration down to 307.5 ng/mL (~ 29% reduction). Combination of concentration ranges of gabapentin between 20 and 40 μg/mL with any morphine concentrations between 100 and 600 ng/mL were found to lead up to 50% increased effect relatively to the effect attained by morphine alone. This study highlights the importance of finding the right combination in multimodal analgesia and demonstrates the usefulness of the response surface approach for the study of pharmacodynamic interactions. The proposed pharmacokinetic-pharmacodynamic model may provide the basis for a rational clinical trial design with the aim to identify the optimal dose combination ratios in humans.

  5. Natural gas conversion to higher hydrocarbons using plasma interactions with surfaces. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Sackinger, W.M.; Kamath, V.A.; Morgan, B.L.; Airey, R.W.

    1993-12-01

    Experiments are reported in which a methane plasma is created, and the methyl ions and hydrogen ions are accelerated within a microchannel array so that they interact with neutral methane molecules on the inside surfaces of the microchannels. No catalysts are used, and the device operates at room temperature. Impact energies of the ions are in the range of 10 eV to greater than 100 eV, and the energy delivered in the interaction at the surfaces causes the production of larger hydrocarbon molecules, such as C{sub 2}H{sub 2}, C{sub 2}H{sub 4}, and C{sub 2}H{sub 6}, along with C{sub 3}, C{sub 4}, C{sub 5}m C{sub 6}, C{sub 7}m and C{sub 8} molecules. There is a decreasing percentage of larger molecules produced, in comparison with the C{sub 2} and C{sub 3} types. Conversion effectiveness is greater at higher pressure, due to the increased ionic activity. The yield of the higher hydrocarbons depends upon the external voltage used, and voltage can be used as a control parameter to adjust the output mixture proportions. A conversion energy of 2.59 kilowatt hours/killogram of output has been demonstrated, and a reduction of this by a factor of 10 is possible using known techniques. In batch experiments, the selectivity for C{sub 2} has varied from 47% to 88%, and selectivity for C{sub 6} has ranged from 0% to 12.8%. Other hydrocarbon selectivities also span a wide and useful range. The estimated costs for hydrocarbons produced with this technology are in the range of $200 per tonne, in production quantities, depending upon natural gas costs. Pilot production experiments are recommended to make these estimates more precise, and to address strategies for scaling the technology up to production levels. Applications are discussed.

  6. Conserved cysteine residues provide a protein-protein interaction surface in dual oxidase (DUOX) proteins.

    Science.gov (United States)

    Meitzler, Jennifer L; Hinde, Sara; Bánfi, Botond; Nauseef, William M; Ortiz de Montellano, Paul R

    2013-03-08

    Intramolecular disulfide bond formation is promoted in oxidizing extracellular and endoplasmic reticulum compartments and often contributes to protein stability and function. DUOX1 and DUOX2 are distinguished from other members of the NOX protein family by the presence of a unique extracellular N-terminal region. These peroxidase-like domains lack the conserved cysteines that confer structural stability to mammalian peroxidases. Sequence-based structure predictions suggest that the thiol groups present are solvent-exposed on a single protein surface and are too distant to support intramolecular disulfide bond formation. To investigate the role of these thiol residues, we introduced four individual cysteine to glycine mutations in the peroxidase-like domains of both human DUOXs and purified the recombinant proteins. The mutations caused little change in the stabilities of the monomeric proteins, supporting the hypothesis that the thiol residues are solvent-exposed and not involved in disulfide bonds that are critical for structural integrity. However, the ability of the isolated hDUOX1 peroxidase-like domain to dimerize was altered, suggesting a role for these cysteines in protein-protein interactions that could facilitate homodimerization of the peroxidase-like domain or, in the full-length protein, heterodimeric interactions with a maturation protein. When full-length hDUOX1 was expressed in HEK293 cells, the mutations resulted in decreased H2O2 production that correlated with a decreased amount of the enzyme localized to the membrane surface rather than with a loss of activity or with a failure to synthesize the mutant proteins. These results support a role for the cysteine residues in intermolecular disulfide bond formation with the DUOX maturation factor DUOXA1.

  7. Surface and interfacial interactions of multilayer graphitic structures with local environment

    Energy Technology Data Exchange (ETDEWEB)

    Mazzocco, R. [Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom); Robinson, B.J., E-mail: b.j.robinson@lancaster.ac.uk [Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom); Rabot, C. [CEA-LETI-Minatec Campus, 17 rue des Martyrs, 38054 Grenoble Cedex 09 (France); Delamoreanu, A. [Microelectronics Technology Laboratory (LTM), Joseph Fourier University, French National Research Center (CNRS), 17 Avenue des Martyrs, 38054 Grenoble Cedex 9 (France); Zenasni, A. [CEA-LETI-Minatec Campus, 17 rue des Martyrs, 38054 Grenoble Cedex 09 (France); Dickinson, J.W.; Boxall, C. [Department of Engineering, Lancaster University, Lancaster LA1 4YR (United Kingdom); Kolosov, O.V. [Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom)

    2015-06-30

    In order to exploit the potential of graphene in next-generation devices, such as supercapacitors, rechargeable batteries, displays and ultrathin sensors, it is crucial to understand the solvent interactions with the graphene surface and interlayers, especially where the latter may be in competition with the former, in the medium of application deployment. In this report, we combine quartz crystal microbalance (QCM) and ultrasonic force microscopy methods to investigate the changes in the film–substrate and film–environment interfaces of graphene and graphene oxide films, produced by diverse scalable routes, in both polar (deionised water) and non-polar (dodecane) liquid and vapour environments. In polar liquid environments, we observe nanobubble adsorption/desorption on the graphene film corresponding to a surface coverage of up to 20%. As no comparable behaviour is observed for non-polar environment, we conclude that nanobubble formation is directly due to the hydrophobic nature of graphene with direct consequences for electrode structures immersed in electrolyte solutions. The amount of water adsorbed by the graphene films was found to vary considerably from 0.012 monolayers of water per monolayer of reduced graphene oxide to 0.231 monolayers of water per monolayer of carbon diffusion growth graphene. This is supported by direct nanomechanical mapping of the films immersed in water where an increased variation of local stiffness suggests water propagation within the film and/or between the film and substrate. Transferred film thickness calculations performed for QCM, atomic force microscopy topography and optical transmission measurements, returns results an order of magnitude larger (46 ± 1 layers) than Raman spectroscopy (1 - 2 graphene layers) on pristine pre-transferred films due to contamination during transfer and possible turbostratic structures of large areas. - Highlights: • Exploring interaction of graphene films with polar and nonpolar liquids

  8. Specific interactions of functionalised gold surfaces with ammonium perchlorate or starch; towards a chemical cartography of their mixture

    Energy Technology Data Exchange (ETDEWEB)

    Mercier, D. [CNRS, UMR CNRS 7609, Laboratoire de Reactivite de Surface, Paris (France); Universite Pierre et Marie Curie - UPMC Paris VI, Laboratoire de Reactivite de Surface, 4 place Jussieu, 75252 Paris Cedex 05 (France); Laboratoire de recherche conventionne CEA/UPMC n Degree-Sign 1, Paris (France); Mercader, C.; Quere, S.; Hairault, L. [CEA, DAM, Le Ripault, F-37260 Monts (France); Laboratoire de recherche conventionne CEA/UPMC n Degree-Sign 1, Paris (France); Methivier, C. [CNRS, UMR CNRS 7609, Laboratoire de Reactivite de Surface, Paris (France); Universite Pierre et Marie Curie - UPMC Paris VI, Laboratoire de Reactivite de Surface, 4 place Jussieu, 75252 Paris Cedex 05 (France); Laboratoire de recherche conventionne CEA/UPMC n Degree-Sign 1, Paris (France); Pradier, C.M., E-mail: claire-Marie.pradier@upmc.fr [CNRS, UMR CNRS 7609, Laboratoire de Reactivite de Surface, Paris (France); Universite Pierre et Marie Curie - UPMC Paris VI, Laboratoire de Reactivite de Surface, 4 place Jussieu, 75252 Paris Cedex 05 (France); Laboratoire de recherche conventionne CEA/UPMC n Degree-Sign 1, Paris (France)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer Measurements of interactions by Quartz Crystal Microbalance. Black-Right-Pointing-Pointer AFM and CFM measurements, tip functionalisation. Black-Right-Pointing-Pointer Surface nano-imaging. - Abstract: By functionalising gold samples, planar wafers or AFM tips, with an acid- or an amino acid-terminated thiols, mercaptoundecanoic acid (MUA) and homocystein (H-Cyst) respectively, we were able to differentiate the interactions with ammonium perchlorate (AP) and starch (S), two components of a nanocomposition mixture. To do so, the interaction between gold functionalized surfaces and the two targeted compounds have been characterized and quantified by several complementary techniques. Polarisation modulation-infrared spectroscopy (PM-IRRAS), and X-ray photoelectron spectroscopy (XPS), providing chemical analyses of gold surfaces after contacting S or AP, proved that both compounds were retained on MUA or H-Cyst-modified surfaces, but to various extents. Quartz crystal microbalance on-line measurements enabled to monitor the kinetics of interaction and showed distinct differences in the behaviour of MUA and H-Cyst-surfaces towards the two compounds. Having observed that only H-Cyst-modified surfaces enables to get a contrast on the chemical force microscopy (CFM) images, this new result could be well explained by examining the data obtained by combining the above-mentioned surface characterisation techniques.

  9. Efficient Capture of Cancer Cells by Their Replicated Surfaces Reveals Multiscale Topographic Interactions Coupled with Molecular Recognition.

    Science.gov (United States)

    Wang, Wenshuo; Cui, Haijun; Zhang, Pengchao; Meng, Jingxin; Zhang, Feilong; Wang, Shutao

    2017-03-29

    Cell-surface topographic interactions can direct the design of biointerfaces, which have been widely used in isolation of circulating tumor cells or fundamental cell biological research. By using three kinds of cancer cell-replicated surfaces with differentiated structures, we uncover that multiscale-cooperative topographic interactions (at both nanoscale and microscale) coupled with molecular recognition enable efficient and specific isolation of cancer cells. The cell replicas precisely inherit the structural features from the original cancer cells, providing not only preferable structures for matching with cancer cells but also a unique platform to interrogate whether certain cancer cells can optimally match with their own replicated surfaces. The results reveal that cancer cells do not show preferential recognitions to their respective replicas, while the capture agent-modified surfaces with hierarchical structures exhibit improved cancer cell capture efficiencies. Two levels of topographic interactions between cancer cells and cell replica surfaces exist. Nanoscale filopodia on cancer cells can topographically interact with different nanostructures on replica surfaces. In addition, microscale concave/convex on surfaces provide suitable sites for trapping cancer cells. This study may promote smart design of multiscale biofunctional materials that can specifically recognize cancer cells.

  10. Interaction of the wood surface with metal ions. Part 3: The effects of light on chromium impregnated wood surface

    International Nuclear Information System (INIS)

    Stipta, J.; Németh, K.; Molnárné Hamvas, L.

    2004-01-01

    UV-light changes of untreated and chromium impregnated wood surface were investigated by absorption spectrophotometric methods. The properties of indifferent silicagel and celulose layers were to the behaviour of poplar and black locust surface. Chromic-ion-impregnation had no significant effect on the absorption spectra of these layers. On the other hand, hexavalent chromium was reduced and UV-light caused irreversible wood degradation. Surface treatment caused considerable modification in black locust

  11. Charge carrier dynamics and surface plasmon interaction in gold nanorod-blended organic solar cell

    Science.gov (United States)

    Rana, Aniket; Gupta, Neeraj; Lochan, Abhiram; Sharma, G. D.; Chand, Suresh; Kumar, Mahesh; Singh, Rajiv K.

    2016-08-01

    The inclusion of plasmonic nanoparticles into organic solar cell enhances the light harvesting properties that lead to higher power conversion efficiency without altering the device configuration. This work defines the consequences of the nanoparticle overloading amount and energy transfer process between gold nanorod and polymer (active matrix) in organic solar cells. We have studied the hole population decay dynamics coupled with gold nanorods loading amount which provides better understanding about device performance limiting factors. The exciton and plasmon together act as an interacting dipole; however, the energy exchange between these two has been elucidated via plasmon resonance energy transfer (PRET) mechanism. Further, the charge species have been identified specifically with respect to their energy levels appearing in ultrafast time domain. The specific interaction of these charge species with respective surface plasmon resonance mode, i.e., exciton to transverse mode of oscillation and polaron pair to longitudinal mode of oscillations, has been explained. Thus, our analysis reveals that PRET enhances the carrier population density in polymer via non-radiative process beyond the concurrence of a particular plasmon resonance oscillation mode and polymer absorption range. These findings give new insight and reveal specifically the factors that enhance and control the performance of gold nanorods blended organic solar cells. This work would lead in the emergence of future plasmon based efficient organic electronic devices.

  12. Charge carrier dynamics and surface plasmon interaction in gold nanorod-blended organic solar cell

    International Nuclear Information System (INIS)

    Rana, Aniket; Lochan, Abhiram; Chand, Suresh; Kumar, Mahesh; Singh, Rajiv K.; Gupta, Neeraj; Sharma, G. D.

    2016-01-01

    The inclusion of plasmonic nanoparticles into organic solar cell enhances the light harvesting properties that lead to higher power conversion efficiency without altering the device configuration. This work defines the consequences of the nanoparticle overloading amount and energy transfer process between gold nanorod and polymer (active matrix) in organic solar cells. We have studied the hole population decay dynamics coupled with gold nanorods loading amount which provides better understanding about device performance limiting factors. The exciton and plasmon together act as an interacting dipole; however, the energy exchange between these two has been elucidated via plasmon resonance energy transfer (PRET) mechanism. Further, the charge species have been identified specifically with respect to their energy levels appearing in ultrafast time domain. The specific interaction of these charge species with respective surface plasmon resonance mode, i.e., exciton to transverse mode of oscillation and polaron pair to longitudinal mode of oscillations, has been explained. Thus, our analysis reveals that PRET enhances the carrier population density in polymer via non-radiative process beyond the concurrence of a particular plasmon resonance oscillation mode and polymer absorption range. These findings give new insight and reveal specifically the factors that enhance and control the performance of gold nanorods blended organic solar cells. This work would lead in the emergence of future plasmon based efficient organic electronic devices.

  13. Interaction force measurement between E. coli cells and nanoparticles immobilized surfaces by using AFM.

    Science.gov (United States)

    Zhang, Wen; Stack, Andrew G; Chen, Yongsheng

    2011-02-01

    To better understand environmental behaviors of nanoparticles (NPs), we used the atomic force microscopy (AFM) to measure interaction forces between E. coli cells and NPs immobilized on surfaces in an aqueous environment. The results showed that adhesion force strength was significantly influenced by particle size for both hematite (α-Fe(2)O(3)) and corundum (α-Al(2)O(3)) NPs whereas the effect on the repulsive force was not observed. The adhesion force decreased from 6.3±0.7nN to 0.8±0.4nN as hematite NPs increased from 26nm to 98nm in diameter. Corundum NPs exhibited a similar dependence of adhesion force on particle size. The Johnson-Kendall-Roberts (JKR) model was employed to estimate the contact area between E. coli cells and NPs, and based on the JKR model a new model that considers local effective contact area was developed. The prediction of the new model matched the size dependence of adhesion force in experimental results. Size effects on adhesion forces may originate from the difference in local effective contact areas as supported by our model. These findings provide fundamental information for interpreting the environmental behaviors and biological interactions of NPs, which barely have been addressed. Copyright © 2010 Elsevier B.V. All rights reserved.

  14. Interaction of arginine, lysine, and guanidine with surface residues of lysozyme: implication to protein stability.

    Science.gov (United States)

    Shah, Dhawal; Shaikh, Abdul Rajjak

    2016-01-01

    Additives are widely used to suppress aggregation of therapeutic proteins. However, the molecular mechanisms of effect of additives to stabilize proteins are still unclear. To understand this, we herein perform molecular dynamics simulations of lysozyme in the presence of three commonly used additives: arginine, lysine, and guanidine. These additives have different effects on stability of proteins and have different structures with some similarities; arginine and lysine have aliphatic side chain, while arginine has a guanidinium group. We analyze atomic contact frequencies to study the interactions of the additives with individual residues of lysozyme. Contact coefficient, quantified from contact frequencies, is helpful in analyzing the interactions with the guanidine groups as well as aliphatic side chains of arginine and lysine. Strong preference for contacts to the additives (over water) is seen for the acidic followed by polar and the aromatic residues. Further analysis suggests that the hydration layer around the protein surface is depleted more in the presence of arginine, followed by lysine and guanidine. Molecular dynamics simulations also reveal that the internal dynamics of protein, as indicated by the lifetimes of the hydrogen bonds within the protein, changes depending on the additives. Particularly, we note that the side-chain hydrogen-bonding patterns within the protein differ with the additives, with several side-chain hydrogen bonds missing in the presence of guanidine. These results collectively indicate that the aliphatic chain of arginine and lysine plays a critical role in the stabilization of the protein.

  15. Nanoscale cellulose films with different crystallinities and mesostructures--their surface properties and interaction with water.

    Science.gov (United States)

    Aulin, Christian; Ahola, Susanna; Josefsson, Peter; Nishino, Takashi; Hirose, Yasuo; Osterberg, Monika; Wågberg, Lars

    2009-07-07

    A systematic study of the degree of molecular ordering and swelling of different nanocellulose model films has been conducted. Crystalline cellulose II surfaces were prepared by spin-coating of the precursor cellulose solutions onto oxidized silicon wafers before regeneration in water or by using the Langmuir-Schaefer (LS) technique. Amorphous cellulose films were also prepared by spin-coating of a precursor cellulose solution onto oxidized silicon wafers. Crystalline cellulose I surfaces were prepared by spin-coating wafers with aqueous suspensions of sulfate-stabilized cellulose I nanocrystals and low-charged microfibrillated cellulose (LC-MFC). In addition, a dispersion of high-charged MFC was used for the buildup of polyelectrolyte multilayers with polyetheyleneimine on silica with the aid of the layer-by-layer (LbL) technique. These preparation methods produced smooth thin films on the nanometer scale suitable for X-ray diffraction and swelling measurements. The surface morphology and thickness of the cellulose films were characterized in detail by atomic force microscopy (AFM) and ellipsometry measurements, respectively. To determine the surface energy of the cellulose surfaces, that is, their ability to engage in different interactions with different materials, they were characterized through contact angle measurements against water, glycerol, and methylene iodide. Small incidence angle X-ray diffraction revealed that the nanocrystal and MFC films exhibited a cellulose I crystal structure and that the films prepared from N-methylmorpholine-N-oxide (NMMO), LiCl/DMAc solutions, using the LS technique, possessed a cellulose II structure. The degree of crystalline ordering was highest in the nanocrystal films (approximately 87%), whereas the MFC, NMMO, and LS films exhibited a degree of crystallinity of about 60%. The N,N-dimethylacetamide (DMAc)/LiCl film possessed very low crystalline ordering (cellulose, and electrostatic charge of the MFC. The swelling of

  16. Interaction of Convective Organization and Monsoon Precipitation, Atmosphere, Surface and Sea (INCOMPASS)

    Science.gov (United States)

    Turner, A. G.; Bhat, G. S.; Evans, J. G.; Madan, R.; Marsham, J. H.; Martin, G.; Mitra, A. K.; Mrudula, G.; Parker, D. J.; Pattnaik, S.; Rajagopal, E. N.; Taylor, C.; Tripathi, S. N.

    2016-12-01

    INCOMPASS will build on a field and aircraft measurement campaign from the 2016 monsoon onset to better understand and predict monsoon rainfall. The monsoon supplies the majority of water in South Asia, however modelling and forecasting the monsoon from days to the season ahead is limited by large model errors that develop quickly. Likely problems lie in physical parametrizations such as convection, the boundary layer and land surface. At the same time, lack of detailed observations prevents more thorough understanding of monsoon circulation and its interaction with the land surface; a process governed by boundary layer and convective cloud dynamics. From May to July 2016, INCOMPASS used a modified BAe-146 jet aircraft operated by the UK Facility for Airborne Atmospheric Measurements (FAAM), for the first project of this scale in India. The India and UK team flew around 100 hours of science sorties from bases in northern and southern India. Flights from Lucknow in the northern plains took measurements to the west and southeast to allow sampling of the complete contrast from dry desert air to the humid environment over the north Bay of Bengal. These routes were repeated in the pre-monsoon and monsoon phases, measuring contrasting surface and boundary layer structures. In addition, flights from the southern base in Bengaluru measured contrasts from the Arabian Sea, across the intense rains of the Western Ghats mountains, over the rain shadow in southeast India and over the southern Bay of Bengal. Flight planning was performed with the aid of forecasts from a new UK Met Office 4km limited area model. INCOMPASS also installed a network of surface flux towers, as well as operating a cloud-base ceilometer and performing intensive radiosonde launches from a supersite in Kanpur. This presentation will outline preliminary results from the field campaign including new observations of the surface, boundary layer structure and atmospheric profiles together with detailed

  17. Multi-purpose mid-plane manipulator for plasma surface interaction research in KSTAR

    Energy Technology Data Exchange (ETDEWEB)

    Son, S.H., E-mail: ssh0609@nfri.re.kr [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Hong, S.-H. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Department of Electrical Engineering, HanYang University, Seoul 133-791 (Korea, Republic of); Department of Accelerator and Nuclear Fusion Physics and Engineering, Korea University of Science and Technology, Daejeon 305-333 (Korea, Republic of); Kim, Junghee [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Kim, Jun Young [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Department of Accelerator and Nuclear Fusion Physics and Engineering, Korea University of Science and Technology, Daejeon 305-333 (Korea, Republic of); Kim, H.S. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Ding, F.; Luo, G.-N. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 1126 (China); Németh, J.; Zoletnik, S. [Institute for Particle and Nuclear Physics (RMI), Wigner RCP, Hungarian Academy of Sciences, Budapest (Hungary); Fenyvesi, A. [Institute for Nuclear Physis (MTA Atomki), Hungarian Academy of Sciences, Devrecent (Hungary); Pitts, R. [ITER Organization, Route de Vinon-surVerdon, 13115 Saint Paul-lez-Durance (France)

    2016-11-01

    Highlights: • A multi-purpose mid-plane manipulator system has been developed and installed at the mid-plane of the KSTAR vacuum vessel. • It presents mechanial structure and function for multi-purpose manipulator system. • The changeable head part allows change the samples and probe during inter-shot/day without breaking vacuum system in KSTAR which gives flexibility for various PSI studies in a campaign. - Abstract: A multi-purpose mid-plane manipulator system has been developed and installed at the mid-plane of the KSTAR vacuum vessel. The system serves as user facility which allows to cover various topics of researches in plasma-surface interaction (PSI) including material sample test and PSI diagnostic. The multi-purpose mid-plane manipulator system has a 4 m long cantilever structure with a 3 m long moving shaft. The system is equipped with a differential pumping system for the independent installation and removal of samples and diagnostic without vacuum break of KSTAR. The sample mounting head at the end of the shaft can reach the position of the outer boundary of ∼10 cm away from the last closed flux surface (LCFS). In this paper, selected PSI related experiments by using the manipulator are introduced.

  18. Surface and Microstructural Failures of PET-Coated ECCS Plates by Salmon-Polymer Interaction

    Directory of Open Access Journals (Sweden)

    Ernesto Zumelzu

    2016-03-01

    Full Text Available The new types of knowledge-intensive, multilayer containers consist of steel plates protected against corrosion by nanometric electrolytic chromium (Cr0 and chromium oxide (Cr2O3 layers chemically bonded to polyethylene terephthalate (PET polymer coating to preserve food. It was observed that after emptying the cans, the salmon adhered to the polymer coating, changing its color, and that this adhesion increased with longer storage times. This work was aimed at determining the product-container interactions and their characterization by X-ray diffraction (XRD, confocal Raman and micro-Raman imaging and scanning electron microscopy (SEM analysis. The zones of adhesion showed surface changes, variations in crystallinity and microstructural degradation of the PET coating. In addition, localized damages altering the functional properties of the multilayer system were observed as microcracking in the chromium layers that protect the steel. The degradation undergone was evaluated and characterized at a surface and microstructural level to establish the failure mechanisms, which were mainly associated with the activity of the adhered muscle and its biochemical components. Finally, a recommendation is done to preserve the useful life and functionality of cans for the preservation and efficient use of resources with an impact on recycling and environmental conservancy.

  19. Interaction of KSHV with Host Cell Surface Receptors and Cell Entry

    Directory of Open Access Journals (Sweden)

    Mohanan Valiya Veettil

    2014-10-01

    Full Text Available Virus entry is a complex process characterized by a sequence of events. Since the discovery of KSHV in 1994, tremendous progress has been made in our understanding of KSHV entry into its in vitro target cells. KSHV entry is a complex multistep process involving viral envelope glycoproteins and several cell surface molecules that is utilized by KSHV for its attachment and entry. KSHV has a broad cell tropism and the attachment and receptor engagement on target cells have an important role in determining the cell type-specific mode of entry. KSHV utilizes heparan sulfate, integrins and EphrinA2 molecules as receptors which results in the activation of host cell pre-existing signal pathways that facilitate the subsequent cascade of events resulting in the rapid entry of virus particles, trafficking towards the nucleus followed by viral and host gene expression. KSHV enters human fibroblast cells by dynamin dependant clathrin mediated endocytosis and by dynamin independent macropinocytosis in dermal endothelial cells. Once internalized into endosomes, fusion of the viral envelope with the endosomal membranes in an acidification dependent manner results in the release of capsids which subsequently reaches the nuclear pore vicinity leading to the delivery of viral DNA into the nucleus. In this review, we discuss the principal mechanisms that enable KSHV to interact with the host cell surface receptors as well as the mechanisms that are required to modulate cell signaling machinery for a successful entry.

  20. Atomistic interactions of clusters on surfaces using molecular dynamics and hyper molecular dynamics

    International Nuclear Information System (INIS)

    Sanz-Navarro, Carlos F.

    2002-01-01

    The work presented in this thesis describes the results of Molecular Dynamics (MD) simulations applied to the interaction of silver clusters with graphite surfaces and some numerical and theoretical methods concerning the extension of MD simulations to longer time scales (hyper-MD). The first part of this thesis studies the implantation of clusters at normal incidence onto a graphite surface in order to determine the scaling of the penetration depth (PD) against the impact energy. A comparison with experimental results is made with good agreement. The main physical observations of the impact process are described and analysed. It is shown that there is a threshold impact velocity above which the linear dependence on PD on impact energy changes to a linear dependence on velocity. Implantation of silver clusters at oblique incidence is also considered. The second part of this work analyses the validity and feasibility of the three minimisation methods for the hyper-MD simulation method whereby time scales of an MD simulation can be extended. A correct mathematical basis for the iterative method is derived. It is found that one of the iterative methods, upon which hyper-lD is based, is very likely to fail in high-dimensional situations because it requires a too expensive convergence. Two new approximations to the hyper-MD approach are proposed, which reduce the computational effort considerably. Both approaches, although not exact, can help to search for some of the most likely transitions in the system. Some examples are given to illustrate this. (author)

  1. Transient analysis of electromagnetic wave interactions on plasmonic nanostructures using a surface integral equation solver

    KAUST Repository

    Uysal, Ismail Enes

    2016-08-09

    Transient electromagnetic interactions on plasmonic nanostructures are analyzed by solving the Poggio-Miller-Chan-Harrington-Wu-Tsai (PMCHWT) surface integral equation (SIE). Equivalent (unknown) electric and magnetic current densities, which are introduced on the surfaces of the nanostructures, are expanded using Rao-Wilton-Glisson and polynomial basis functions in space and time, respectively. Inserting this expansion into the PMCHWT-SIE and Galerkin testing the resulting equation at discrete times yield a system of equations that is solved for the current expansion coefficients by a marching on-in-time (MOT) scheme. The resulting MOT-PMCHWT-SIE solver calls for computation of additional convolutions between the temporal basis function and the plasmonic medium\\'s permittivity and Green function. This computation is carried out with almost no additional cost and without changing the computational complexity of the solver. Time-domain samples of the permittivity and the Green function required by these convolutions are obtained from their frequency-domain samples using a fast relaxed vector fitting algorithm. Numerical results demonstrate the accuracy and applicability of the proposed MOT-PMCHWT solver. © 2016 Optical Society of America.

  2. Multi-purpose mid-plane manipulator for plasma surface interaction research in KSTAR

    International Nuclear Information System (INIS)

    Son, S.H.; Hong, S.-H.; Kim, Junghee; Kim, Jun Young; Kim, H.S.; Ding, F.; Luo, G.-N.; Németh, J.; Zoletnik, S.; Fenyvesi, A.; Pitts, R.

    2016-01-01

    Highlights: • A multi-purpose mid-plane manipulator system has been developed and installed at the mid-plane of the KSTAR vacuum vessel. • It presents mechanial structure and function for multi-purpose manipulator system. • The changeable head part allows change the samples and probe during inter-shot/day without breaking vacuum system in KSTAR which gives flexibility for various PSI studies in a campaign. - Abstract: A multi-purpose mid-plane manipulator system has been developed and installed at the mid-plane of the KSTAR vacuum vessel. The system serves as user facility which allows to cover various topics of researches in plasma-surface interaction (PSI) including material sample test and PSI diagnostic. The multi-purpose mid-plane manipulator system has a 4 m long cantilever structure with a 3 m long moving shaft. The system is equipped with a differential pumping system for the independent installation and removal of samples and diagnostic without vacuum break of KSTAR. The sample mounting head at the end of the shaft can reach the position of the outer boundary of ∼10 cm away from the last closed flux surface (LCFS). In this paper, selected PSI related experiments by using the manipulator are introduced.

  3. Interactions of small platinum clusters with the TiC(001) surface

    International Nuclear Information System (INIS)

    Mao, Jianjun; Li, Shasha; Chu, Xingli; Yang, Zongxian

    2015-01-01

    Density functional theory calculations are used to elucidate the interactions of small platinum clusters (Pt n , n = 1–5) with the TiC(001) surface. The results are analyzed in terms of geometric, energetic, and electronic properties. It is found that a single Pt atom prefers to be adsorbed at the C-top site, while a Pt 2 cluster prefers dimerization and a Pt 3 cluster forms a linear structure on the TiC(001). As for the Pt 4 cluster, the three-dimensional distorted tetrahedral structure and the two-dimensional square structure almost have equal stability. In contrast with the two-dimensional isolated Pt 5 cluster, the adsorbed Pt 5 cluster prefers a three-dimensional structure on TiC(001). Substantial charge transfer takes place from TiC(001) surface to the adsorbed Pt n clusters, resulting in the negatively charged Pt n clusters. At last, the d-band centers of the absorbed Pt atoms and their implications in the catalytic activity are discussed

  4. Kinetics of interaction from low-energy-ion bombardment of surfaces

    International Nuclear Information System (INIS)

    Horton, C.C.

    1988-01-01

    The kinetics of interaction from low energy oxygen ion bombardment of carbon and Teflon surfaces have been investigated. The surfaces were bombarded with 4.5 to 93 eV oxygen ions and emitted species were observed with a mass spectrometer. To obtain the kinetic information, the ion beam was square pulse modulated and reaction products were observed as a function of time. The kinetic information is contained in the response of the emitted species to the pulsed ion beam. Oxygen bombardment of carbon produced CO in three parallel branches with each following an adsorption-desorption process. The fast branch, with a rate constants of 12,000/sec, appeared to be sputter induced an was absent below about 19 eV. The medium and slow branches, with rate constants of 850/sec and 45/sec respectively, has little energy dependence and appeared to be due to chemical sputtering from two sites. The ratio of the fraction of the medium branch to that of the slow was constant at 1:3. The bombardment of Teflon produced CF in two parallel branches, with one following a series process and the other an adsorb-desorb process. The rate constant of the other branch were 22,000/sec and 7,000/sec and the rate constant of the other branch was 90/sec. The total signal fell monotonically with decreasing ion energy with the fraction for each branch holding constant at 71% for the series and 29% for the adsorb-desorb

  5. Predicting Ligand Binding Sites on Protein Surfaces by 3-Dimensional Probability Density Distributions of Interacting Atoms

    Science.gov (United States)

    Jian, Jhih-Wei; Elumalai, Pavadai; Pitti, Thejkiran; Wu, Chih Yuan; Tsai, Keng-Chang; Chang, Jeng-Yih; Peng, Hung-Pin; Yang, An-Suei

    2016-01-01

    Predicting ligand binding sites (LBSs) on protein structures, which are obtained either from experimental or computational methods, is a useful first step in functional annotation or structure-based drug design for the protein structures. In this work, the structure-based machine learning algorithm ISMBLab-LIG was developed to predict LBSs on protein surfaces with input attributes derived from the three-dimensional probability density maps of interacting atoms, which were reconstructed on the query protein surfaces and were relatively insensitive to local conformational variations of the tentative ligand binding sites. The prediction accuracy of the ISMBLab-LIG predictors is comparable to that of the best LBS predictors benchmarked on several well-established testing datasets. More importantly, the ISMBLab-LIG algorithm has substantial tolerance to the prediction uncertainties of computationally derived protein structure models. As such, the method is particularly useful for predicting LBSs not only on experimental protein structures without known LBS templates in the database but also on computationally predicted model protein structures with structural uncertainties in the tentative ligand binding sites. PMID:27513851

  6. Interaction of KSHV with Host Cell Surface Receptors and Cell Entry

    Science.gov (United States)

    Veettil, Mohanan Valiya; Bandyopadhyay, Chirosree; Dutta, Dipanjan; Chandran, Bala

    2014-01-01

    Virus entry is a complex process characterized by a sequence of events. Since the discovery of KSHV in 1994, tremendous progress has been made in our understanding of KSHV entry into its in vitro target cells. KSHV entry is a complex multistep process involving viral envelope glycoproteins and several cell surface molecules that is utilized by KSHV for its attachment and entry. KSHV has a broad cell tropism and the attachment and receptor engagement on target cells have an important role in determining the cell type-specific mode of entry. KSHV utilizes heparan sulfate, integrins and EphrinA2 molecules as receptors which results in the activation of host cell pre-existing signal pathways that facilitate the subsequent cascade of events resulting in the rapid entry of virus particles, trafficking towards the nucleus followed by viral and host gene expression. KSHV enters human fibroblast cells by dynamin dependant clathrin mediated endocytosis and by dynamin independent macropinocytosis in dermal endothelial cells. Once internalized into endosomes, fusion of the viral envelope with the endosomal membranes in an acidification dependent manner results in the release of capsids which subsequently reaches the nuclear pore vicinity leading to the delivery of viral DNA into the nucleus. In this review, we discuss the principal mechanisms that enable KSHV to interact with the host cell surface receptors as well as the mechanisms that are required to modulate cell signaling machinery for a successful entry. PMID:25341665

  7. Effect of glucosamine sulfate on surface interactions and lubrication by hydrogenated soy phosphatidylcholine (HSPC) liposomes.

    Science.gov (United States)

    Gaisinskaya-Kipnis, Anastasia; Jahn, Sabrina; Goldberg, Ronit; Klein, Jacob

    2014-11-10

    Glucosamine sulfate (GAS) is a charged monosaccharide molecule that is widely used as a treatment for osteoarthritis, a joint disease related to friction and lubrication of articular cartilage. Using a surface force balance, we examine the effect of GAS on normal and, particularly, on shear (frictional) interactions between surfaces in an aqueous environment coated with small unilamellar vesicles (SUVs), or liposomes, of hydrogenated soy phosphatidylcholine (HSPC). We examine the effect of GAS solution, pure water, and salt solution (0.15 M NaNO3) both inside and outside the vesicles. Cryoscanning electron microscopy shows a closely packed layer of liposomes whose morphology is affected only slightly by GAS. HSPC-SUVs with encapsulated GAS are stable upon shear at high compressions (>100 atm) and provide very good lubrication when immersed both in pure water and physiological-level salt solutions (in the latter case, the liposomes are exceptionally stable and lubricious up to >400 atm). The low friction is attributed to several parameters based on the hydration lubrication mechanism.

  8. Study of plasma-material surface interaction using Langmuir probe technique during plasma treatment

    International Nuclear Information System (INIS)

    Saloum, S.; Akel, M.

    2009-06-01

    In this study, we tried to understand the plasma-surface interactions by using Langmuir probes. Two different types of plasmas were studied, the first is the electropositive plasma in Argon and the second is the electronegative plasma in Sulfur Hexafluoride. In the first type, the effects of Argon gas pressure, the injection of Helium in the remote zone and the substrate bias on the measurements of the Electron Energy Probability Function (EEPF) and on the plasma parameters (electron density (n e ), effective electron temperature (T e ff), plasma potential (V p ) and floating potential (V f )) have been investigated. The obtained EEPFs and plasma parameters have been used to control two remote plasma processes. The first is the remote Plasma Enhanced Chemical Vapor Deposition (PE-CVD) of thin films, on silicon wafers, from Hexamethyldisoloxane (HMDSO) precursor diluted in the remote Ar-He plasma. The second is the pure Argon remote plasma treatment of polymethylmethacrylate (PMMA) polymer surface. In the second type, the plasma diagnostics were performed in the remote zone as a function of SF 6 flow rate, where relative concentrations of fluorine atoms were measured using actinometry optical emission spectroscopy; electron density, electron temperature and plasma potential were determined using single cylindrical Langmuir probe, positive ion flux and negative ion fraction were determined using an planar probe. The silicon etching process in SF 6 plasma was studied. (author)

  9. Interaction of Human Tumor Viruses with Host Cell Surface Receptors and Cell Entry

    Directory of Open Access Journals (Sweden)

    Georgia Schäfer

    2015-05-01

    Full Text Available Currently, seven viruses, namely Epstein-Barr virus (EBV, Kaposi’s sarcoma-associated herpes virus (KSHV, high-risk human papillomaviruses (HPVs, Merkel cell polyomavirus (MCPyV, hepatitis B virus (HBV, hepatitis C virus (HCV and human T cell lymphotropic virus type 1 (HTLV-1, have been described to be consistently associated with different types of human cancer. These oncogenic viruses belong to distinct viral families, display diverse cell tropism and cause different malignancies. A key to their pathogenicity is attachment to the host cell and entry in order to replicate and complete their life cycle. Interaction with the host cell during viral entry is characterized by a sequence of events, involving viral envelope and/or capsid molecules as well as cellular entry factors that are critical in target cell recognition, thereby determining cell tropism. Most oncogenic viruses initially attach to cell surface heparan sulfate proteoglycans, followed by conformational change and transfer of the viral particle to secondary high-affinity cell- and virus-specific receptors. This review summarizes the current knowledge of the host cell surface factors and molecular mechanisms underlying oncogenic virus binding and uptake by their cognate host cell(s with the aim to provide a concise overview of potential target molecules for prevention and/or treatment of oncogenic virus infection.

  10. Investigating the effect of surface water - groundwater interactions on stream temperature using Distributed temperature sensing and instream temperature model

    DEFF Research Database (Denmark)

    Karthikeyan, Matheswaran; Blemmer, Morten; Mortensen, Julie Flor

    2011-01-01

    Surface water–groundwater interactions at the stream interface influences, and at times controls the stream temperature, a critical water property driving biogeochemical processes. This study investigates the effects of these interactions on temperature of Stream Elverdamsåen in Denmark using...... the Distributed Temperature Sensing (DTS) system and instream temperature modelling. Locations of surface water–groundwater interactions were identified from the temperature data collected over a 2-km stream reach using a DTS system with 1-m spatial and 5-min temporal resolution. The stream under consideration...... exhibits three distinct thermal regimes within a 2 km reach length due to two major interactions. An energy balance model is used to simulate the instream temperature and to quantify the effect of these interactions on the stream temperature. This research demonstrates the effect of reach level small scale...

  11. Groundwater sustainability and groundwater/surface-water interaction in arid Dunhuang Basin, northwest China

    Science.gov (United States)

    Lin, Jingjing; Ma, Rui; Hu, Yalu; Sun, Ziyong; Wang, Yanxin; McCarter, Colin P. R.

    2018-03-01

    The Dunhuang Basin, a typical inland basin in northwestern China, suffers a net loss of groundwater and the occasional disappearance of the Crescent Lake. Within this region, the groundwater/surface-water interactions are important for the sustainability of the groundwater resources. A three-dimensional transient groundwater flow model was established and calibrated using MODFLOW 2000, which was used to predict changes to these interactions once a water diversion project is completed. The simulated results indicate that introducing water from outside of the basin into the Shule and Danghe rivers could reverse the negative groundwater balance in the Basin. River-water/groundwater interactions control the groundwater hydrology, where river leakage to the groundwater in the Basin will increase from 3,114 × 104 m3/year in 2017 to 11,875 × 104 m3/year in 2021, and to 17,039 × 104 m3/year in 2036. In comparison, groundwater discharge to the rivers will decrease from 3277 × 104 m3/year in 2017 to 1857 × 104 m3/year in 2021, and to 510 × 104 m3/year by 2036; thus, the hydrology will switch from groundwater discharge to groundwater recharge after implementing the water diversion project. The simulation indicates that the increased net river infiltration due to the water diversion project will raise the water table and then effectively increasing the water level of the Crescent Lake, as the lake level is contiguous with the water table. However, the regional phreatic evaporation will be enhanced, which may intensify soil salinization in the Dunhuang Basin. These results can guide the water allocation scheme for the water diversion project to alleviate groundwater depletion and mitigate geo-environmental problem.

  12. A field comparison of multiple techniques to quantify groundwater - surface-water interactions

    Science.gov (United States)

    González-Pinzón, Ricardo; Ward, Adam S; Hatch, Christine E; Wlostowski, Adam N; Singha, Kamini; Gooseff, Michael N.; Haggerty, Roy; Harvey, Judson; Cirpka, Olaf A; Brock, James T

    2015-01-01

    Groundwater–surface-water (GW-SW) interactions in streams are difficult to quantify because of heterogeneity in hydraulic and reactive processes across a range of spatial and temporal scales. The challenge of quantifying these interactions has led to the development of several techniques, from centimeter-scale probes to whole-system tracers, including chemical, thermal, and electrical methods. We co-applied conservative and smart reactive solute-tracer tests, measurement of hydraulic heads, distributed temperature sensing, vertical profiles of solute tracer and temperature in the stream bed, and electrical resistivity imaging in a 450-m reach of a 3rd-order stream. GW-SW interactions were not spatially expansive, but were high in flux through a shallow hyporheic zone surrounding the reach. NaCl and resazurin tracers suggested different surface–subsurface exchange patterns in the upper ⅔ and lower ⅓ of the reach. Subsurface sampling of tracers and vertical thermal profiles quantified relatively high fluxes through a 10- to 20-cm deep hyporheic zone with chemical reactivity of the resazurin tracer indicated at 3-, 6-, and 9-cm sampling depths. Monitoring of hydraulic gradients along transects with MINIPOINT streambed samplers starting ∼40 m from the stream indicated that groundwater discharge prevented development of a larger hyporheic zone, which progressively decreased from the stream thalweg toward the banks. Distributed temperature sensing did not detect extensive inflow of ground water to the stream, and electrical resistivity imaging showed limited large-scale hyporheic exchange. We recommend choosing technique(s) based on: 1) clear definition of the questions to be addressed (physical, biological, or chemical processes), 2) explicit identification of the spatial and temporal scales to be covered and those required to provide an appropriate context for interpretation, and 3) maximizing generation of mechanistic understanding and reducing costs of

  13. Interaction of phosphorylcholine with fibronectin coatings: Surface characterization and biological performances

    Energy Technology Data Exchange (ETDEWEB)

    Montaño-Machado, Vanessa, E-mail: vanessa.montano-machado.1@ulaval.ca [Laboratory for Biomaterials and Bioengineering, Dept. of Min-Met-Materials Eng., & University Hospital Research Center, Laval University, University Campus, PLT-1745G, Québec, Québec, G1 V 0A6 (Canada); ERRMECe, University of Cergy-Pontoise, Site Saint-Martin, 2 Avenue Adolphe Chauvin, 95302 Cergy-Pontoise Cedex (France); Noël, Céline, E-mail: celine.noel@unamur.be [Research Centre in Physics of Matter and Radiation (PMR), Université de Namur, 61 rue de Bruxelles, B-5000 Namur (Belgium); Chevallier, Pascale, E-mail: pascale.chevallier@crchudequebec.ulaval.ca [Laboratory for Biomaterials and Bioengineering, Dept. of Min-Met-Materials Eng., & University Hospital Research Center, Laval University, University Campus, PLT-1745G, Québec, Québec, G1 V 0A6 (Canada); Turgeon, Stéphane, E-mail: stephane.turgeon@crchudequebec.ulaval.ca [Laboratory for Biomaterials and Bioengineering, Dept. of Min-Met-Materials Eng., & University Hospital Research Center, Laval University, University Campus, PLT-1745G, Québec, Québec, G1 V 0A6 (Canada); Houssiau, Laurent, E-mail: laurent.houssiau@unamur.be [Research Centre in Physics of Matter and Radiation (PMR), Université de Namur, 61 rue de Bruxelles, B-5000 Namur (Belgium); Pauthe, Emmanuel, E-mail: emmanuel.pauthe@u-cergy.fr [ERRMECe, University of Cergy-Pontoise, Site Saint-Martin, 2 Avenue Adolphe Chauvin, 95302 Cergy-Pontoise Cedex (France); and others

    2017-02-28

    Highlights: • Fibronectin/phosphorylcholine coatings on plasma deposited fluorocarbon films were created. • The effect of several coating techniques on the surface biological performances was evaluated. • XPS, DWCA, immunostaining and ToF-SIMS (imaging and depth profiling) techniques were applied. • Potential for cardiovascular applications was showed by endothelial cell and blood interactions. - Abstract: Coating medical devices with several bioactive molecules is an interesting approach to achieve specific biological targets upon the interaction of the biomaterial with the living environment. In this work, a fluorocarbon polymer (CF{sub x}) was first deposited by plasma treatment on stainless steel (SS) substrate and thereafter, coatings containing fibronectin (FN) and phosphorylcholine (PRC) were created for cardiovascular applications. These two biomolecules were chosen to promote endothelialization and to avoid thrombus formation, respectively. Adsorption and grafting techniques were applied – and combined – to accomplish 4 different coatings containing both molecules. However, big challenge was found to characterize a small molecule (PRC: 184 g/mol) interacting with a protein (FN: 450 kD). For the first time XPS, dynamic water contact angle, immunostaining and ToF-SIMS (imaging and depth profiling) analyses were combined to accomplish the characterization of such a coating. The most encouraging biological performances were obtained for samples where FN was grafted to the CF{sub x} film followed by the adsorption of PRC: proliferation of endothelial cells and hemocompatibility properties were observed. Promising coatings for cardiovascular applications were developed. The relevance of characterizing the coatings with high sensitive techniques and the further correlation with their biological performances were evidenced.

  14. GPU-based interactive cut-surface extraction from high-order finite element fields.

    Science.gov (United States)

    Nelson, Blake; Haimes, Robert; Kirby, Robert M

    2011-12-01

    We present a GPU-based ray-tracing system for the accurate and interactive visualization of cut-surfaces through 3D simulations of physical processes created from spectral/hp high-order finite element methods. When used by the numerical analyst to debug the solver, the ability for the imagery to precisely reflect the data is critical. In practice, the investigator interactively selects from a palette of visualization tools to construct a scene that can answer a query of the data. This is effective as long as the implicit contract of image quality between the individual and the visualization system is upheld. OpenGL rendering of scientific visualizations has worked remarkably well for exploratory visualization for most solver results. This is due to the consistency between the use of first-order representations in the simulation and the linear assumptions inherent in OpenGL (planar fragments and color-space interpolation). Unfortunately, the contract is broken when the solver discretization is of higher-order. There have been attempts to mitigate this through the use of spatial adaptation and/or texture mapping. These methods do a better job of approximating what the imagery should be but are not exact and tend to be view-dependent. This paper introduces new rendering mechanisms that specifically deal with the kinds of native data generated by high-order finite element solvers. The exploratory visualization tools are reassessed and cast in this system with the focus on image accuracy. This is accomplished in a GPU setting to ensure interactivity. © 2011 IEEE

  15. Groundwater/surface-water interaction in central Sevier County, Tennessee, October 2015–2016

    Science.gov (United States)

    Carmichael, John K.; Johnson, Gregory C.

    2017-12-14

    The U.S. Geological Survey evaluated the interaction of groundwater and surface water in the central part of Sevier County, Tennessee, from October 2015 through October 2016. Stream base flow was surveyed in December 2015 and in July and October 2016 to evaluate losing and gaining stream reaches along three streams in the area. During a July 2016 synoptic survey, groundwater levels were measured in wells screened in the Cambrian-Ordovician aquifer to define the potentiometric surface in the area. The middle and lower reaches of the Little Pigeon River and the middle reaches of Middle Creek and the West Prong Little Pigeon River were gaining streams at base-flow conditions. The lower segments of the West Prong Little Pigeon River and Middle Creek were losing reaches under base-flow conditions, with substantial flow losses in the West Prong Little Pigeon River and complete subsurface diversion of flow in Middle Creek through a series of sinkholes that developed in the streambed and adjacent flood plain beginning in 2010. The potentiometric surface of the Cambrian-Ordovician aquifer showed depressed water levels in the area where loss of flow occurred in the lower reaches of West Prong Little Pigeon River and Middle Creek. Continuous dewatering activities at a rock quarry located in this area appear to have lowered groundwater levels by as much as 180 feet, which likely is the cause of flow losses observed in the two streams, and a contributing factor to the development of sinkholes at Middle Creek near Collier Drive.

  16. Surface Energy Determined by Inverse Gas Chromatography as a Tool to Investigate Particulate Interactions in Dry Powder Inhalers.

    Science.gov (United States)

    Das, Shyamal C; Tucker, Ian G; Stewart, Peter J

    2015-01-01

    Dry powder inhalers (DPIs) usually contain drug particles powder particles used in DPI to characterize materials and to understand aerosolization behaviour. Early studies used an infinite dilution technique to determine nonpolar surface energy and free energy of adsorption for polar interactions separately. Although some correlations were observed with the change in nonpolar surface energy before and after micronization, milling and storage, a lack of consistency in the change of free energy of adsorption was common. Moreover, a consistent relationship between complex de-agglomeration behaviour and surface energy has not been established and there are even some examples of negative correlation. In fact, nonpolar surface energy at infinite dilution is an incomplete representation of powder surface characteristics. The techniques for measuring polar surface energy, total surface energy and surface energy distribution have provided more revealing information about surface energetics of powders. Surface energy distributions determined by IGC or surface energy analyser have been successfully used to understand energetic heterogeneity of surfaces, characterize different polymorphs and understand changes due to micronization, structural relaxation, dry coating and storage. Efforts have been made to utilize surface energy distribution data to calculate powder strength distribution and to explain complex de-agglomeration behaviour of DPI formulations.

  17. Interaction between surface wind and ocean circulation in the Carolina Capes in a coupled low-order model

    Energy Technology Data Exchange (ETDEWEB)

    Xie, L.; Pietrafesa, L.J.; Raman, S.

    1997-03-18

    Interactions between surface winds and ocean currents over an east-coast continental shelf are studied using a simple mathematical model. The model physics include cross-shelf advection of sea surface temperature (SST) by Ekman drift, upwelling due to Ekman transport divergence, differential heating of the low-level atmosphere by a cross-shelf SST gradient, and the Coriolis effect. Additionally, the effects of diabatic cooling of surface waters due to air-sea heat exchange and of the vertical density stratification on the thickness of the upper ocean Ekman layer are considered. The model results are qualitatively consistent with observed wind-driven coastal ocean circulation and surface wind signatures induced by SST. This simple model also demonstrates that two-way air-sea interaction plays a significant role in the subtidal frequency variability of coastal ocean circulation and mesoscale variability of surface wind fields over coastal waters.

  18. MSATT Workshop on Innovative Instrumentation for the In Situ Study of Atmosphere-Surface Interactions on Mars

    Science.gov (United States)

    Fegley, Bruce, Jr. (Editor); Waenke, Heinrich (Editor)

    1992-01-01

    Papers accepted for the Mars Surface and Atmosphere Through Time (MSATT) Workshop on Innovative Instruments for the In Situ Study of Atmosphere-Surface Interaction of Mars, 8-9 Oct. 1992 in Mainz, Germany are included. Topics covered include: a backscatter Moessbauer spectrometer (BaMS) for use on Mars; database of proposed payloads and instruments for SEI missions; determination of martian soil mineralogy and water content using the Thermal Analyzer for Planetary Soils (TAPS); in situ identification of the martian surface material and its interaction with the martian atmosphere using DTA/GC; mass spectrometer-pyrolysis experiment for atmospheric and soil sample analysis on the surface of Mars; and optical luminescence spectroscopy as a probe of the surface mineralogy of Mars.

  19. Hydrogeologic framework and groundwater/surface-water interactions of the Chehalis River basin, Washington

    Science.gov (United States)

    Gendaszek, Andrew S.

    2011-01-01

    The Chehalis River has the largest drainage basin of any river entirely contained within the State of Washington with a watershed of approximately 2,700 mi2 and has correspondingly diverse geology and land use. Demands for water resources have prompted the local citizens and governments of the Chehalis River basin to coordinate with Federal, State and Tribal agencies through the Chehalis Basin Partnership to develop a long-term watershed management plan. The recognition of the interdependence of groundwater and surface-water resources of the Chehalis River basin became the impetus for this study, the purpose of which is to describe the hydrogeologic framework and groundwater/surface-water interactions of the Chehalis River basin. Surficial geologic maps and 372 drillers' lithostratigraphic logs were used to generalize the basin-wide hydrogeologic framework. Five hydrogeologic units that include aquifers within unconsolidated glacial and alluvial sediments separated by discontinuous confining units were identified. These five units are bounded by a low permeability unit comprised of Tertiary bedrock. A water table map, and generalized groundwater-flow directions in the surficial aquifers, were delineated from water levels measured in wells between July and September 2009. Groundwater generally follows landsurface-topography from the uplands to the alluvial valley of the Chehalis River. Groundwater gradients are highest in tributary valleys such as the Newaukum River valley (approximately 23 cubic feet per mile), relatively flat in the central Chehalis River valley (approximately 6 cubic feet per mile), and become tidally influenced near the outlet of the Chehalis River to Grays Harbor. The dynamic interaction between groundwater and surface-water was observed through the synoptic streamflow measurements, termed a seepage run, made during August 2010, and monitoring of water levels in wells during the 2010 Water Year. The seepage run revealed an overall gain of 56

  20. Groundwater/Surface-Water Interaction in the Context of South African Water Policy

    Science.gov (United States)

    Levy, J.; Xu, Y.

    2010-12-01

    Groundwater/surface-water interaction is receiving increasing focus in Africa due to its importance to ecologic systems and sustainability. South Africa’s 1998 National Water Act (NWA) recognized water as a basic human right and its importance for ecological sustainability. Ecological integrity of water resources was considered an important component in redressing past social inequities, eliminating poverty, and encouraging economic development. Under the NWA, groundwater-use licenses are granted only after setting aside the groundwater Reserve, the amount of water needed to supply basic human needs and preserve a minimum degree of ecological integrity. One challenge to successful implementation of the NWA, therefore, is the accurate quantification of groundwater contributions to aquatic ecosystems. This is especially true considering that so many of South Africa’s aquifers are in highly heterogeneous and anisotropic fractured-rock settings. The most common approach taken in South Africa is estimation of average annual flux rates at the regional scale of quaternary catchments with baseflow separation techniques and then applying a water-budget approach, subtracting the groundwater discharge rate from the recharge rate. The water-balance approach might be a good first step, but it ignores spatial and temporal variability, potentially missing the local impacts associated with placement of production boreholes. Identification of discrete areas of groundwater discharge could be achieved with stable-isotopic and geochemical analyses and vegetative mapping. Groundwater-flow modeling should be used where possible as it holistically incorporates available data and can predict impacts of groundwater extraction and development based on the relative positions of boreholes and surface-water bodies. Sustainable development entails recognition of the trade-offs between preservation and development. There will always be scientific uncertainty associated with estimation and

  1. Land-atmosphere interactions due to anthropogenic and natural changes in the land surface: A numerical modeling study

    Science.gov (United States)

    Yang, Zhao

    Alterations to the land surface can be attributed to both human activity and natural variability. Human activities, such as urbanization and irrigation, can change the conditions of the land surface by altering albedo, soil moisture, aerodynamic roughness length, the partitioning of net radiation into sensible and latent heat, and other surface characteristics. On the other hand, natural variability, manifested through changes in atmospheric circulation, can also induce land surface changes. These regional scale land surface changes, induced either by humans or natural variability, can effectively modify atmospheric conditions through land-atmosphere interactions. However, only in recent decades have numerical models begun to include representations of the critical processes driving changes at the land surface, and their associated effects on the overlying atmosphere. In this work we explore three mechanisms by which changes to the land surface - both anthropogenic and naturally induced - impact the overlying atmosphere and affect regional hydroclimate. (Abstract shortened by ProQuest.).

  2. On the interaction of a submerged turbulent jet with a clean or contaminated free surface

    Science.gov (United States)

    Anthony, Douglas G.; Hirsa, Amir; Willmarth, William W.

    1991-02-01

    The effect of a free surface on the structure of a submerged turbulent jet is investigated experimentally. Three-component LDV measurements beneath a clean free surface show that the mean flow spreads laterally outward in a shallow surface layer much wider than the mean flow well below the surface. As the free surface is approached, velocity fluctuations normal to the surface are diminished while those parallel to the surface are enhanced. Laser-induced fluorescence is used to show that the surface layer contains fluid ejected from the jet. With the addition of surface-active agents, the surface layer is suppressed.

  3. Molecular dynamics study of the interactions of incident N or Ti atoms with the TiN(001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhenhai [National Key Laboratory for Precision Hot Processing of Metals & School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Centre for Precision Manufacturing, Department of Design, Manufacture and Engineering Management, The University of Strathclyde, Glasgow G1 1XJ (United Kingdom); Zeng, Quanren [Centre for Precision Manufacturing, Department of Design, Manufacture and Engineering Management, The University of Strathclyde, Glasgow G1 1XJ (United Kingdom); Yuan, Lin [National Key Laboratory for Precision Hot Processing of Metals & School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Qin, Yi [Centre for Precision Manufacturing, Department of Design, Manufacture and Engineering Management, The University of Strathclyde, Glasgow G1 1XJ (United Kingdom); Chen, Mingjun [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Shan, Debin, E-mail: d.b.shan@gmail.com [National Key Laboratory for Precision Hot Processing of Metals & School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2016-01-01

    Graphical abstract: - Highlights: • Interactions of incident N or Ti atoms with TiN(001) surface are studied by CMD. • The impact position of incident N on the surface determines the interaction modes. • Adsorption could occur due to the atomic exchange process. • Resputtering and reflection may simultaneously occur. • The initial sticking coefficient of N on TiN(001) is much smaller than that of Ti. - Abstract: The interaction processes between incident N or Ti atoms and the TiN(001) surface are simulated by classical molecular dynamics based on the second nearest-neighbor modified embedded-atom method potentials. The simulations are carried out for substrate temperatures between 300 and 700 K and kinetic energies of the incident atoms within the range of 0.5–10 eV. When N atoms impact against the surface, adsorption, resputtering and reflection of particles are observed; several unique atomic mechanisms are identified to account for these interactions, in which the adsorption could occur due to the atomic exchange process while the resputtering and reflection may simultaneously occur. The impact position of incident N atoms on the surface plays an important role in determining the interaction modes. Their occurrence probabilities are dependent on the kinetic energy of incident N atoms but independent on the substrate temperature. When Ti atoms are the incident particles, adsorption is the predominant interaction mode between particles and the surface. This results in the much smaller initial sticking coefficient of N atoms on the TiN(001) surface compared with that of Ti atoms. Stoichiometric TiN is promoted by N/Ti flux ratios larger than one.

  4. Simultaneous characterization of protein-material and cell-protein interactions using dynamic QCM-D analysis on SAM surfaces.

    Science.gov (United States)

    Kushiro, Keiichiro; Lee, Chih-Hao; Takai, Madoka

    2016-05-24

    Understanding the interactions among materials, proteins and cells is critical for the development of novel biomaterials, and establishing a highly sensitive and quantitative method to standardize these interactions is desired. In this study, quartz crystal microbalance with dissipation (QCM-D) combined with microscopy was utilized to quantitatively monitor the entirety of the cell adhesion processes, starting from the protein adsorption, on various self-assembled monolayer (SAM) surfaces. Although the resulting cell adhesion morphologies were similar on most of the surfaces, the dynamic QCM-D signal patterns were unique on each surface, suggesting different forms of material-protein-cell interactions. The viscoelasticity and the density of the surface-adsorbed fibronectin (FN), as well as the relative exposure of the cell adhesive arginine-glycine-aspartic acid (RGD) motifs, were correlated to the different cell adhesion dynamics and mechanics. Some surfaces exhibited complicated behaviors alluding to the detachment/rearrangement of surface proteins or highly sparse but bioactive proteins that promote a slow adhesion process. This study underscores the potential use of the QCM-D signal pattern as a rule of thumb for delineating different protein-material and cell-protein interactions, and offers a rapid in vitro platform for the dynamic evaluation of protein and cell behaviors on novel biomaterials.

  5. Influence of surface chemistry of carbon materials on their interactions with inorganic nitrogen contaminants in soil and water.

    Science.gov (United States)

    Sumaraj; Padhye, Lokesh P

    2017-10-01

    Inorganic nitrogen contaminants (INC) (NH 4 + , NO 3 - , NO 2 - , NH 3 , NO, NO 2 , and N 2 O) pose a growing risk to the environment, and their remediation methods are highly sought after. Application of carbon materials (CM), such as biochar and activated carbon, to remediate INC from agricultural fields and wastewater treatment plants has gained a significant interest since past few years. Understanding the role of surface chemistry of CM in adsorption of various INC is highly critical to increase adsorption efficiency as well as to assess the long term impact of using these highly recalcitrant CM for remediation of INC. Critical reviews of adsorption studies related to INC have revealed that carbon surface chemistry (surface functional groups, pH, Eh, elemental composition, and mineral content) has significant influence on adsorption of INC. Compared to basic functional groups, oxygen containing surface functional groups have been found to be more influential for adsorption of INC. However, basic sites on carbon materials still play an important role in chemisorption of anionic INC. Apart from surface functional groups, pH, Eh and pH zpc of CM and elemental and mineral composition of its surface are important properties capable of altering INC interactions with CM. This review summarizes our current understanding of INC interactions with CM's surface through the known chemisorption mechanisms: electrostatic interaction, hydrogen bonding, electron donor-acceptor mechanism, hydrophobic and hydrophilic interaction, chemisorption aided by minerals, and interactions influenced by pH and elemental composition. Change in surface chemistry of CM in soil during aging is also discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Groundwater and surface-water interactions near White Bear Lake, Minnesota, through 2011

    Science.gov (United States)

    Jones, Perry M.; Trost, Jared J.; Rosenberry, Donald O.; Jackson, P. Ryan; Bode, Jenifer A.; O'Grady, Ryan M.

    2013-01-01

    The U.S. Geological Survey, in cooperation with the White Bear Lake Conservation District, the Minnesota Pollution Control Agency, the Minnesota Department of Natural Resources, and other State, county, municipal, and regional planning agencies, watershed organizations, and private organizations, conducted a study to characterize groundwater and surface-water interactions near White Bear Lake through 2011. During 2010 and 2011, White Bear Lake and other lakes in the northeastern part of the Twin Cities Metropolitan Area were at historically low levels. Previous periods of lower water levels in White Bear Lake correlate with periods of lower precipitation; however, recent urban expansion and increased pumping from the Prairie du Chien-Jordan aquifer have raised the question of whether a decline in precipitation is the primary cause for the recent water-level decline in White Bear Lake. Understanding and quantifying the amount of groundwater inflow to a lake and water discharge from a lake to aquifers is commonly difficult but is important in the management of lake levels. Three methods were used in the study to assess groundwater and surface-water interactions on White Bear Lake: (1) a historical assessment (1978-2011) of levels in White Bear Lake, local groundwater levels, and their relation to historical precipitation and groundwater withdrawals in the White Bear Lake area; (2) recent (2010-11) hydrologic and water-quality data collected from White Bear Lake, other lakes, and wells; and (3) water-balance assessments for White Bear Lake in March and August 2011. An analysis of covariance between average annual lake-level change and annual precipitation indicated the relation between the two variables was significantly different from 2003 through 2011 compared with 1978 through 2002, requiring an average of 4 more inches of precipitation per year to maintain the lake level. This shift in the linear relation between annual lake-level change and annual precipitation

  7. Groundwater and surface-water interaction within the upper Smith River Watershed, Montana 2006-2010

    Science.gov (United States)

    Caldwell, Rodney R.; Eddy-Miller, Cheryl A.

    2013-01-01

    The 125-mile long Smith River, a tributary of the Missouri River, is highly valued as an agricultural resource and for its many recreational uses. During a drought starting in about 1999, streamflow was insufficient to meet all of the irrigation demands, much less maintain streamflow needed for boating and viable fish habitat. In 2006, the U.S. Geological Survey, in cooperation with the Meagher County Conservation District, initiated a multi-year hydrologic investigation of the Smith River watershed. This investigation was designed to increase understanding of the water resources of the upper Smith River watershed and develop a detailed description of groundwater and surface-water interactions. A combination of methods, including miscellaneous and continuous groundwater-level, stream-stage, water-temperature, and streamflow monitoring was used to assess the hydrologic system and the spatial and temporal variability of groundwater and surface-water interactions. Collectively, data are in agreement and show: (1) the hydraulic connectedness of groundwater and surface water, (2) the presence of both losing and gaining stream reaches, (3) dynamic changes in direction and magnitude of water flow between the stream and groundwater with time, (4) the effects of local flood irrigation on groundwater levels and gradients in the watershed, and (5) evidence and timing of irrigation return flows to area streams. Groundwater flow within the alluvium and older (Tertiary) basin-fill sediments generally followed land-surface topography from the uplands to the axis of alluvial valleys of the Smith River and its tributaries. Groundwater levels were typically highest in the monitoring wells located within and adjacent to streams in late spring or early summer, likely affected by recharge from snowmelt and local precipitation, leakage from losing streams and canals, and recharge from local flood irrigation. The effects of flood irrigation resulted in increased hydraulic gradients

  8. Conformational study of protein interactions with hydrogen-passivated amorphous silicon surfaces: Effect of pH

    Science.gov (United States)

    Brahmi, Yamina; Filali, Larbi; Sib, Jamal Dine; Bouhekka, Ahmed; Benlakehal, Djamel; Bouizem, Yahya; Kebab, Aissa; Chahed, Larbi

    2017-11-01

    The adsorption of Bovine Serum Albumin (BSA) proteins on amorphous silicon (a-Si) surfaces was studied with respect to solution pH. Thin films of a-Si were deposited using radio-frequency magnetron sputtering at room temperature and then treated in a hydrogen ambient to form a hydrogenated a-Si surface layer (a-Si:H). The interactions of the as-deposited and hydrogenated surfaces with the proteins at neutral, acidic, and basic environments was probed by means of Fourier transform infrared attenuated total reflection (FTIR-ATR) spectroscopy, Spectroscopic Ellipsometry (SE), and Atomic Force Microscopy (AFM), to study the influence of the charge of proteins on their adsorption and conformation on the a-Si:H surface, compared with the a-Si surface. The results show that the charge of the proteins has a significant effect on their interactions with these two substrates but in dissimilar ways. For the as-deposited substrate, these interactions are predictably coulombic since the surface is charged. For the hydrogenated substrate, the adsorption of the proteins depends on their conformation which is heavily affected by pH, and the size of their footprint (adsorption mode) on the surface.

  9. Atomic interactions at the (100) diamond surface and the impact of surface and interface changes on the electronic transport properties

    Science.gov (United States)

    Deferme, Wim

    Centuries and centuries already, diamond is a material that speaks to ones imagination. Till the 18th century it was only mined in India, after it was also found in Brazil and South-Africa. But along the fascinating properties of diamond, it is also a very interesting material for industry. After the discovery at the end of the 18th century that diamond consists of carbon, it took until the 50's of the previous century before research groups from Russia, Japan and the USA were able to reproduce the growth process of diamond. In 1989 it was discovered that the surface of intrinsic, insulation diamond can be made conductive by hydrogenating the surface. It was clear that not only hydrogen at the surface but also the so called "adsorbates" were responsible for this conductivity. It was still not completely clear what was the influence of other species (like oxygen) on the mechanism of surface conductivity and therefore in this thesis the influence of oxygen on the electronic transport properties of atomically flat diamond are researched. Besides the growth of atomically flat diamond with the use of CVD (chemical vapour deposition) en the study of the grown surfaces with characterising techniques such as AFM (atomic force microscopy) and STM (scanning tunnelling microscopy), the study of the surface treatment with plasma techniques is the main topic of this thesis. The influence of oxygen on the surface conductivity is studied and with the ToF (Time-of-Flight) technique the transport properties of the freestanding diamond are examined. With a short laserflash, electrons and holes are created at the diamond/aluminium interface and due to an electric field (up to 500V) the charge carriers are translated to the back contact. In this way the influence of the surface and the changes at the aluminum contacts is studied leading to very interesting results.

  10. Fundamental properties of molecules on surfaces. Molecular switching and interaction of magnetic molecules with superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Hatter, Nino

    2016-12-14

    In this thesis, we investigate individual molecular switches and metal-organic complexes on surfaces with scanning tunneling microscopy (STM) and spectroscopy (STS) at low temperatures. One focus addresses the switching ability and mechanism of diarylethene on Ag(111). The other focus lies on resolving and tuning magnetic interactions of individual molecules with superconductors. 4,4'-(4,4'-(perfluorocyclopent-1-ene-1,2-diyl)bis (5-methylthiophene-4,2-diyl)dip yridine (PDTE) is a prototypical photochromic switch. We can induce a structural change of individual PDTE molecules on Ag(111) with the STM tip. This change is accompanied by a reduction of the energy gap between the occupied and unoccupied molecular orbitals. Density functional theory (DFT) calculations reveal that the induced switching corresponds to a ring-closing reaction from an open isomer in a flat adsorption configuration to a ring-closed isomer with its methyl groups in a cis configuration. The final product is thermodynamically stabilized by strong dispersion interactions with the surface. A linear dependence of the switching threshold with the tip-sample distance with a minimal threshold of 1.4 V is found, which we assign to a combination of an electric-field induced process and a tunneling-electron contribution. DFT calculations suggest a large activation barrier for a ring-closing reaction from the open flat configuration into the closed cis configuration. The interaction of magnetic molecules with superconductors is studied on manganese phthalocyanine (MnPc) adsorbed on Pb(111). We find triplets of Shiba states inside the superconducting gap. Different adsorption sites of MnPc provide a large variety of exchange coupling strengths, which lead to a collective energy shift of the Shiba triplets. We can assign the splitting of the Shiba states to be an effect of magnetic anisotropy in the system. A quantum phase transition from a ''Kondo screened'' to a &apos

  11. Soy-based Polymers for Surface Modification and Interactions with Lignocellulosic Materials

    Science.gov (United States)

    Salas Araujo, Carlos Luis

    Recent environmental concerns about the use of synthetic materials that are often used to maintain our quality of life has triggered a significant amount of research to develop new technologies and to adopt sustainable, bio-based materials. Cellulose, lignin and other plant-derived macromolecules including proteins from soybeans have witnessed recent, renewed interest by the industrial and scientific communities. For example, soybean proteins have been proposed for a variety of applications, including wood adhesives, bio-plastics, composites and functional materials that may include synthetic polymers. Despite its importance in such systems or materials, very little is known about the fundamental nature of the interactions between soy proteins and other polymers. Therefore, this work addresses this issue by a systematic investigation of the interactions between soy proteins with the two most abundant macromolecules in the biosphere, namely, cellulose and lignin and with the most widely used synthetic polymer, polypropylene (PP). The adsorption of the main soy protein globulins, glycinin (11S) and beta-conglycinin (7S), was studied by using ultrathin films of cellulose, lignin and PP (as well as reference silica and organic self-assembled monolayers (SAMs) surfaces) that were used as substrates. The extent and dynamics of adsorption was monitored by using quartz crystal microgravimetry with dissipation (QCM-D), surface plasmon resonance (SPR) as well as complementary techniques including circular dichroism (CD) and atomic force microscopy (AFM). QCM-D experiments indicated that soy protein adsorption was strongly affected by changes in the physicochemical environment. An increased adsorption of glycinin on silica (by 13%) and cellulose (by 89%) was observed with the increased ionic strength of the aqueous solution, from 0 to 0.1 M NaCl. This highlights the relevance of electrostatic interactions in the adsorption process. In contrast, the adsorption of beta

  12. Greenhouse Gases and Gas-Water-Rock Interactions at the Surface of Early Mars

    Science.gov (United States)

    Murphy, W. M.; Bass, D. S.

    1998-09-01

    Consideration of multiphase equilibria is required to make realistic speculations of conditions on early Mars and can provide indications of modern exploration targets to aid characterization of that remote environment. Greenhouse gases are proposed to sustain elevated surface temperatures compatible with geomorphologic evidence for the stability of liquid water on early Mars. CO2 is commonly invoked as a greenhouse gas at pressures up to 5 bars or more, e.g., [1]. However, solid-gas equilibria show that CO2 pressure is limited by formation of CO2 ice in the upper atmosphere for surface pressure of 2 bars [2]. Recently, SO2 at 10-7 bar in a 2 bar CO2 atmosphere (0.1 ppmv SO2) has been postulated to augment warming in the upper atmosphere on early Mars [3], which could inhibit CO2 precipitation. However, oxidation of SO2 would produce sulfuric acid which dissolves in liquid water and attacks rock components, producing metal sulfate solutions and precipitating gypsum (CaSO4-2H2O). Occurrence of gypsum in SNC meteorites demonstrates conditions permitting oxidation of SO2 on Mars [4]. Equilibrium aqueous speciation calculations show that at low O2 pressure, 10-11 bar of SO2 (i.e., 4 orders of magnitude less than proposed) at equilibrium with water generates sulfuric acid of pH 0.5. Reaction path calculations indicate that silicate minerals would dissolve rapidly in this solution with precipitation of a silica phase, clay minerals, and gypsum. Precipitation of gypsum would deplete atmospheric SO2. These multiphase interactions demonstrate that greenhouse stabilization of liquid water due to an SO2 pressure of 10-7 bar is incompatible with a realistic water-rock system. In the absence of elevated concentrations of atmospheric SO2, at elevated CO2 pressure, and at near neutral pH, geochemical equilibrium models predict that the mineral nahcolite (NaHCO3) may precipitate as a consequence of gas-water-rock interactions. If observed, this mineral could be used together with

  13. Role of bacterial surface structures on the interaction of Klebsiella pneumoniae with phagocytes.

    Directory of Open Access Journals (Sweden)

    Catalina March

    Full Text Available Phagocytosis is a key process of the immune system. The human pathogen Klebsiella pneumoniae is a well known example of a pathogen highly resistant to phagocytosis. A wealth of evidence demonstrates that the capsule polysaccharide (CPS plays a crucial role in resistance to phagocytosis. The amoeba Dictyostelium discoideum shares with mammalian macrophages the ability to phagocytose and kill bacteria. The fact that K. pneumoniae is ubiquitous in nature and, therefore, should avoid predation by amoebae, poses the question whether K. pneumoniae employs similar means to counteract amoebae and mammalian phagocytes. Here we developed an assay to evaluate K. pneumoniae-D. discoideum interaction. The richness of the growth medium affected the threshold at which the cps mutant was permissive for Dictyostelium and only at lower nutrient concentrations the cps mutant was susceptible to predation by amoebae. Given the critical role of bacterial surface elements on host-pathogen interactions, we explored the possible contribution of the lipopolysaccharide (LPS and outer membrane proteins (OMPs to combat phagoyctosis by D. discoideum. We uncover that, in addition to the CPS, the LPS O-polysaccharide and the first core sugar participate in Klebsiella resistance to predation by D. discoideum. K. pneumoniae LPS lipid A decorations are also necessary to avoid predation by amoebae although PagP-dependent palmitoylation plays a more important role than the lipid A modification with aminoarabinose. Mutants lacking OMPs OmpA or OmpK36 were also permissive for D. discoideium growth. Except the LPS O-polysaccharide mutants, all mutants were more susceptible to phagocytosis by mouse alveolar macrophages. Finally, we found a correlation between virulence, using the pneumonia mouse model, and resistance to phagocytosis. Altogether, this work reveals novel K. pneumoniae determinants involved in resistance to phagocytosis and supports the notion that Dictyostelium amoebae

  14. The mechanical interactions between an American football cleat and playing surfaces in-situ at loads and rates generated by elite athletes: a comparison of playing surfaces.

    Science.gov (United States)

    Kent, Richard; Forman, Jason L; Crandall, Jeff; Lessley, David

    2015-03-01

    This study quantified the mechanical interactions between an American football cleat and eight surfaces used by professional American football teams. Loading conditions were applied with a custom-built testing apparatus designed to represent play-relevant maneuvers of elite athletes. Two natural grass and six infill artificial surfaces were tested with the cleated portion of a shoe intended for use on either surface type. In translation tests with a 2. 8-kN vertical load, the grass surfaces limited the horizontal force on the cleats by tearing. This tearing was not observed with the artificial surfaces, which allowed less motion and generated greater horizontal force (3.2 kN vs. 4.5 kN, p force on the natural surfaces than on the artificial surfaces (2.4 kN vs. 3.0 kN, p force-limiting mechanism inherent to natural grass surfaces. Future work should consider implications of these findings for performance and injury risk and should evaluate the findings' sensitivity to cleat pattern and playing conditions.

  15. The effect of surface treatment on the surface texture and contact angle of electrochemically deposited hydroxyapatite coating and on its interaction with bone-forming cells.

    Science.gov (United States)

    Eliaz, Noam; Shmueli, Sharon; Shur, Irena; Benayahu, Dafna; Aronov, Daniel; Rosenman, Gil

    2009-10-01

    This work demonstrates the effects of both surface preparation and surface post-treatment by exposure to electron beam on the surface texture, contact angle and the interaction with bone-forming cells of electrochemically deposited hydroxyapatite (HAp) coating. Both the surface texture and the contact angle of the ground titanium substrate changed as a result of either heat treatment following soaking in NaOH solution or soaking in H(2)O(2) solution. Consequently, the shape of the current transients during potentiostatic deposition of HAp changed, and the resulting coatings exhibited different surface textures and contact angles. The developed interfacial area ratio Sdr and the core fluid retention index Sci were found more reliable than the mean roughness R(a) and the root-mean-square roughness Z(rms) in correlating the adhesion of the coating to the metal substrate and the cellular response with surface texture. The NaOH pretreatment provided the highest surface area and induced the highest cell attachment, even though the H(2)O(2) treatment provided the highest hydrophilicity to the metal substrate. Electrodeposition at pH 6 was found preferable compared to electrodeposition at pH 4.2. The ability to modify the cellular response by exposure to unique electron-beam surface treatment was demonstrated. The very high hydrophilicity of the as-deposited HAp coating enhanced its bioactivity.

  16. Jet-Surface Interaction: High Aspect Ratio Nozzle Test, Nozzle Design and Preliminary Data

    Science.gov (United States)

    Brown, Clifford; Dippold, Vance

    2015-01-01

    The Jet-Surface Interaction High Aspect Ratio (JSI-HAR) nozzle test is part of an ongoing effort to measure and predict the noise created when an aircraft engine exhausts close to an airframe surface. The JSI-HAR test is focused on parameters derived from the Turbo-electric Distributed Propulsion (TeDP) concept aircraft which include a high-aspect ratio mailslot exhaust nozzle, internal septa, and an aft deck. The size and mass flow rate limits of the test rig also limited the test nozzle to a 16:1 aspect ratio, half the approximately 32:1 on the TeDP concept. Also, unlike the aircraft, the test nozzle must transition from a single round duct on the High Flow Jet Exit Rig, located in the AeroAcoustic Propulsion Laboratory at the NASA Glenn Research Center, to the rectangular shape at the nozzle exit. A parametric nozzle design method was developed to design three low noise round-to-rectangular transitions, with 8:1, 12:1, and 16: aspect ratios, that minimizes flow separations and shocks while providing a flat flow profile at the nozzle exit. These designs validated using the WIND-US CFD code. A preliminary analysis of the test data shows that the actual flow profile is close to that predicted and that the noise results appear consistent with data from previous, smaller scale, tests. The JSI-HAR test is ongoing through October 2015. The results shown in the presentation are intended to provide an overview of the test and a first look at the preliminary results.

  17. Role of Surface Interactions in the Synergizing Polymer/Clay Flame Retardant Properties

    Energy Technology Data Exchange (ETDEWEB)

    Pack, S.; Kashiwagi, T; Cao, C; Korach, C; Lewin, M; Rafailovich, M

    2010-01-01

    The absorption of resorcinol di(phenyl phosphate) (RDP) oligomers on clay surfaces has been studied in detail and is being proposed as an alternative method for producing functionalized clays for nanocomposite polymers. The ability of these clays to be exfoliated or intercalated in different homopolymers was investigated using both transmission electron microscopy and small-angle X-ray scattering results, compared with contact angle measurements on Langmuir-Blodgett clay monolayers, where the interfacial energies were used as predictors of the polymer/clay interactions. We found that the contact angle between PS/RDP clay monolayer substrates was {approx}2.5{sup o}, whereas the angle for polystyrene (PS)/Cloisite 20A clays substrates was {approx}32{sup o}, consistent with the large degree of exfoliation observed in PS for the RDP-coated clays. The interfacial activity of these clays was also measured, and we found that the RDP-coated clays segregated to the interfaces of PC/poly(styrene-co-acrylonitrile) blends, while they segregated into the poly(methyl methacrylate) (PMMA) domain of PS/PMMA blends. This morphology was explained in terms of the relative energy advantage in placing the RDP versus the Cloisite clays at the interfaces. Finally, we demonstrated the effects of the relative surface energies of the clays in segregating to the blend air interface when heated to high temperatures. The segregation was shown to affect the composition and mechanical properties of the resulting chars, which in turn could determine their flame retardant response.

  18. Nanoscale control of energy and matter in plasma-surface interactions: towards energy-efficient nanotech

    Science.gov (United States)

    Ostrikov, Kostya

    2010-11-01

    This presentation focuses on the plasma issues related to the solution of the grand challenge of directing energy and matter at nanoscales. This ability is critical for the renewable energy and energy-efficient technologies for sustainable future development. It will be discussed how to use environmentally and human health benign non-equilibrium plasma-solid systems and control the elementary processes of plasma-surface interactions to direct the fluxes of energy and matter at multiple temporal and spatial scales. In turn, this makes it possible to achieve the deterministic synthesis of self- organised arrays of metastable nanostructures in the size range beyond the reach of the present-day nanofabrication. Such structures have tantalising prospects to enhance performance of nanomaterials in virtually any area of human activity yet remain almost inaccessible because the Nature's energy minimisation rules allow only a small number of stable equilibrium states. By using precisely controlled and kinetically fast nanoscale transfer of energy and matter under non-equilibrium conditions and harnessing numerous plasma- specific controls of species creation, delivery to the surface, nucleation and large-scale self-organisation of nuclei and nanostructures, the arrays of metastable nanostructures can be created, arranged, stabilised, and further processed to meet the specific requirements of the envisaged applications. These approaches will eventually lead to faster, unprecedentedly- clean, human-health-friendly, and energy-efficient nanoscale synthesis and processing technologies for the next-generation renewable energy and light sources, biomedical devices, information and communication systems, as well as advanced functional materials for applications ranging from basic food, water, health and clean environment needs to national security and space missions.

  19. Defining an Abrasion Index for Lunar Surface Systems as a Function of Dust Interaction Modes and Variable Concentration Zones

    Science.gov (United States)

    Kobrick, Ryan L.; Klaus, David M.; Street, Kenneth W., Jr.

    2010-01-01

    Unexpected issues were encountered during the Apollo era of lunar exploration due to detrimental abrasion of materials upon exposure to the fine-grained, irregular shaped dust on the surface of the Moon. For critical design features involving contact with the lunar surface and for astronaut safety concerns, operational concepts and dust tolerance must be considered in the early phases of mission planning. To systematically define material selection criteria, dust interaction can be characterized by two-body or three-body abrasion testing, and subcategorically by physical interactions of compression, rolling, sliding and bending representing specific applications within the system. Two-body abrasion occurs when a single particle or asperity slides across a given surface removing or displacing material. Three-body abrasion occurs when multiple particles interact with a solid surface, or in between two surfaces, allowing the abrasives to freely rotate and interact with the material(s), leading to removal or displacement of mass. Different modes of interaction are described in this paper along with corresponding types of tests that can be utilized to evaluate each configuration. In addition to differential modes of abrasion, variable concentrations of dust in different zones can also be considered for a given system design and operational protocol. These zones include: (1) outside the habitat where extensive dust exposure occurs, (2) in a transitional zone such as an airlock or suitport, and (3) inside the habitat or spacesuit with a low particle count. These zones can be used to help define dust interaction frequencies, and corresponding risks to the systems and/or crew can be addressed by appropriate mitigation strategies. An abrasion index is introduced that includes the level of risk, R, the hardness of the mineralogy, H, the severity of the abrasion mode, S, and the frequency of particle interactions, F.

  20. Oblique interaction of a laminar vortex ring with a non-deformable free surface: Vortex reconnection and breakdown

    International Nuclear Information System (INIS)

    Balakrishnan, S K; Thomas, T G; Coleman, G N

    2011-01-01

    Direct Numerical Simulation (DNS) is used to study the interaction of a laminar vortex ring with a non-deformable, free-slip surface at an oblique angle of incidence. The interaction leads to the well-known phenomenon of vortex reconnection. It was found that the reconnection process leads to rapid production of small-scale vortical structures. This phenomenon was found to be related to the kinematics of the reconection process.

  1. Dynamic Morphological Changes Induced By GM1 and Protein Interactions on the Surface of Cell-Sized Liposomes

    Directory of Open Access Journals (Sweden)

    Masahiro Takagi

    2013-06-01

    Full Text Available It is important to understand the physicochemical mechanisms that are responsible for the morphological changes in the cell membrane in the presence of various stimuli such as osmotic pressure. Lipid rafts are believed to play a crucial role in various cellular processes. It is well established that Ctb (Cholera toxin B subunit recognizes and binds to GM1 (monosialotetrahexosylganglioside on the cell surface with high specificity and affinity. Taking advantage of Ctb-GM1 interaction, we examined how Ctb and GM1 molecules affect the dynamic movement of liposomes. GM1 a natural ligand for cholera toxin, was incorporated into liposome and the interaction between fluorescent Ctb and the liposome was analyzed. The interaction plays an important role in determining the various surface interaction phenomena. Incorporation of GM1 into membrane leads to an increase of the line tension leading to either rupture of liposome membrane or change in the morphology of the membrane. This change in morphology was found to be GM1 concentration specific. The interaction between Ctb-GM1 leads to fast and easy rupture or to morphological changes of the liposome. The interactions of Ctb and the glycosyl chain are believed to affect the surface and the curvature of the membrane. Thus, the results are highly beneficial in the study of signal transduction processes.

  2. Groundwater Surface Water Interactions in a Gold-Mined Dredged Floodplain of the Merced River

    Science.gov (United States)

    Sullivan, L.; Conklin, M. H.; Ghezzehei, T. A.

    2012-12-01

    The Merced River, originating in the Sierra Nevada, California, drains a watershed with an area of ~3,305 km2. Merced River has been highly altered due to diversions, mechanically dredged mining, and damming. A year of groundwater-surface water interactions were studied to elucidate the hydrological connection between the Main Canal, an unlined canal that contains Merced River water flows parallel to the river with an average elevation of 89m, the highly conductive previously dredged floodplain, and the Merced River with an average elevation of 84m. Upstream of the study reach, located in an undredged portion, of the floodplain are two fish farms that have been operating for approximately 40 years. This study reach has been historically important for salmon spawning and rearing, where more than 50% of the Chinook salmon of the Merced River spawn. Currently salmon restoration is focusing gravel augmentation and adding side channel and ignoring groundwater influences. Exchanges between the hyporheic and surrounding surface, groundwater, riparian, and alluvial floodplain habitats occur over a wide range of spatial and temporal scales. Pressure transducers were installed in seven wells and four ponds located in the dredged floodplain. All wells were drilled to the Mehrten Formation, a confining layer, and screened for last 3m. These groundwater well water levels as well as the surface water elevations of the Main Canal and the Merced River were used to determine the direction of sublateral surface flows using Groundwater Vistas as a user interface for MODFLOW. The well and pond waters and seepage from the river banks were sampled for anion/cation, dissolved organic carbon, total nitrogen, total iron, and total dissolved iron concentrations to determine water sources and the possibility of suboxic water. Field analysis indicated that water in all wells and ponds exhibit low dissolved oxygen, high conductivity rates, and oxidation/reduction potentials that switched from

  3. Fluorescence and confocal microscopy studies of the ice surface - antifreeze protein interactions.

    Science.gov (United States)

    Pertaya, N.; Thomson, E.; Davies, P. L.; Braslavsky, I.

    2005-03-01

    Biomineralization is a phenomenon in which biological material influences mineral growth on the molecular level. A compelling example involves antifreeze proteins (AFPs) known to prevent fish and insects from freezing. AFPs have many potential applications in agriculture, biomedical science, and can be used as a model platform to understand biomineralization processes for future nanotechnology applications. Here we describe a new approach to study the interaction between AFPs and ice using fluorescence and confocal microscopy combined with a unique ice growth cell. After conjugating green fluorescent protein (GFP) to Type III AFP, we imaged the fluorescence signal around and inside of the ice crystals that emerged from the cooled AFP-GFP solution, and have observed an enhanced fluorescence signal at the edge of the ice crystal. In a second cell we observed a dramatic change in the ice growth morphology when AFPs were introduced into an initially pure system. Further developments of these methods will permit the direct imaging of the location and concentration of the AFPs on ice surfaces and enable a better understanding of their operation. Supported by CIHR, the Bosack and Kruger Foundation, Ohio and Yale Universities.

  4. Groundwater/surface-water interactions in the Bad River Watershed, Wisconsin

    Science.gov (United States)

    Leaf, Andrew T.; Fienen, Michael N.; Hunt, Randall J.; Buchwald, Cheryl A.

    2015-11-23

    A groundwater-flow model was developed for the Bad River Watershed and surrounding area by using the U.S. Geological Survey (USGS) finite-difference code MODFLOW-NWT. The model simulates steady-state groundwater-flow and base flow in streams by using the streamflow routing (SFR) package. The objectives of this study were to: (1) develop an improved understanding of the groundwater-flow system in the Bad River Watershed at the regional scale, including the sources of water to the Bad River Band of Lake Superior Chippewa Reservation (Reservation) and groundwater/surface-water interactions; (2) provide a quantitative platform for evaluating future impacts to the watershed, which can be used as a starting point for more detailed investigations at the local scale; and (3) identify areas where more data are needed. This report describes the construction and calibration of the groundwater-flow model that was subsequently used for analyzing potential locations for the collection of additional field data, including new observations of water-table elevation for refining the conceptualization and corresponding numerical model of the hydrogeologic system.

  5. Features of protein-protein interactions that translate into potent inhibitors: topology, surface area and affinity.

    Science.gov (United States)

    Smith, Matthew C; Gestwicki, Jason E

    2012-07-26

    Protein-protein interactions (PPIs) control the assembly of multi-protein complexes and, thus, these contacts have enormous potential as drug targets. However, the field has produced a mix of both exciting success stories and frustrating challenges. Here, we review known examples and explore how the physical features of a PPI, such as its affinity, hotspots, off-rates, buried surface area and topology, might influence the chances of success in finding inhibitors. This analysis suggests that concise, tight binding PPIs are most amenable to inhibition. However, it is also clear that emerging technical methods are expanding the repertoire of 'druggable' protein contacts and increasing the odds against difficult targets. In particular, natural product-like compound libraries, high throughput screens specifically designed for PPIs and approaches that favour discovery of allosteric inhibitors appear to be attractive routes. The first group of PPI inhibitors has entered clinical trials, further motivating the need to understand the challenges and opportunities in pursuing these types of targets.

  6. MDM2-MDM4 molecular interaction investigated by atomic force spectroscopy and surface plasmon resonance.

    Science.gov (United States)

    Moscetti, Ilaria; Teveroni, Emanuela; Moretti, Fabiola; Bizzarri, Anna Rita; Cannistraro, Salvatore

    Murine double minute 2 (MDM2) and 4 (MDM4) are known as the main negative regulators of p53, a tumor suppressor. They are able to form heterodimers that are much more effective in the downregulation of p53. Therefore, the MDM2-MDM4 complex could be a target for promising therapeutic restoration of p53 function. To this aim, a deeper understanding of the molecular mechanisms underlining the heterodimerization is needed. The kinetic and thermodynamic characterization of the MDM2-MDM4 complex was performed with two complementary approaches: atomic force spectroscopy and surface plasmon resonance. Both techniques revealed an equilibrium dissociation constant (KD ) in the micromolar range for the MDM2-MDM4 heterodimer, similar to related complexes involved in the p53 network. Furthermore, the MDM2-MDM4 complex is characterized by a relatively high free energy, through a single energy barrier, and by a lifetime in the order of tens of seconds. New insights into the MDM2-MDM4 interaction could be highly important for developing innovative anticancer drugs focused on p53 reactivation.

  7. Artificial Intelligence Mechanisms on Interactive Modified Simplex Method with Desirability Function for Optimising Surface Lapping Process

    Directory of Open Access Journals (Sweden)

    Pongchanun Luangpaiboon

    2014-01-01

    Full Text Available A study has been made to optimise the influential parameters of surface lapping process. Lapping time, lapping speed, downward pressure, and charging pressure were chosen from the preliminary studies as parameters to determine process performances in terms of material removal, lap width, and clamp force. The desirability functions of the-nominal-the-best were used to compromise multiple responses into the overall desirability function level or D response. The conventional modified simplex or Nelder-Mead simplex method and the interactive desirability function are performed to optimise online the parameter levels in order to maximise the D response. In order to determine the lapping process parameters effectively, this research then applies two powerful artificial intelligence optimisation mechanisms from harmony search and firefly algorithms. The recommended condition of (lapping time, lapping speed, downward pressure, and charging pressure at (33, 35, 6.0, and 5.0 has been verified by performing confirmation experiments. It showed that the D response level increased to 0.96. When compared with the current operating condition, there is a decrease of the material removal and lap width with the improved process performance indices of 2.01 and 1.14, respectively. Similarly, there is an increase of the clamp force with the improved process performance index of 1.58.

  8. A heat transfer correlation based on a surface renewal model for molten core concrete interaction study

    International Nuclear Information System (INIS)

    Tourniaire, B. . E-mail bruno.tourniaire@cea.fr

    2006-01-01

    The prediction of heat transfer between corium pool and concrete basemat is of particular significance in the framework of the study of PWR's severe accident. Heat transfer directly governs the ablation velocity of concrete in case of molten core concrete interaction (MCCI) and, consequently, the time delay when the reactor cavity may fail. From a restricted hydrodynamic point of view, this issue is related to heat transfer between a heated bubbling pool and a porous wall with gas injection. Several experimental studies have been performed with simulant materials and many correlations have been provided to address this issue. The comparisons of the results of these correlations with the measurements and their extrapolation to reactor materials show that strong discrepancies between the results of these models are obtained which probably means that some phenomena are not well taken into account. The main purpose of this paper is to present an alternative heat transfer model which was originally developed for chemical engineering applications (bubble columns) by Deckwer. A part of this work is devoted to the presentation of this model, which is based on a surface renewal assumption. Comparison of the results of this model with available experimental data in different systems are presented and discussed. These comparisons clearly show that this model can be used to deal with the particular problem of MCCI. The analyses also lead to enrich the original model by taking into account the thermal resistance of the wall: a new formulation of the Deckwer's correlation is finally proposed

  9. Charge transfer dynamics from adsorbates to surfaces with single active electron and configuration interaction based approaches

    Energy Technology Data Exchange (ETDEWEB)

    Ramakrishnan, Raghunathan, E-mail: r.ramakrishnan@unibas.ch [Institute of Physical Chemistry, National Center for Computational Design and Discovery of Novel Materials (MARVEL), Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel (Switzerland); Nest, Mathias [Theoretische Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching (Germany)

    2015-01-13

    Highlights: • We model electron dynamics across cyano alkanethiolates attached to gold cluster. • We present electron transfer time scales from TD-DFT and TD-CI based simulations. • Both DFT and CI methods qualitatively predict the trend in time scales. • TD-CI predicts the experimental relative time scale very accurately. - Abstract: We employ wavepacket simulations based on many-body time-dependent configuration interaction (TD-CI), and single active electron theories, to predict the ultrafast molecule/metal electron transfer time scales, in cyano alkanethiolates bonded to model gold clusters. The initial states represent two excited states where a valence electron is promoted to one of the two virtual π{sup ∗} molecular orbitals localized on the cyanide fragment. The ratio of the two time scales indicate the efficiency of one charge transfer channel over the other. In both our one-and many-electron simulations, this ratio agree qualitatively with each other as well as with the previously reported experimental time scales (Blobner et al., 2012), measured for a macroscopic metal surface. We study the effect of cluster size and the description of electron correlation on the charge transfer process.

  10. Wave-current interaction near the Gulf Stream during the surface wave dynamics experiment

    Science.gov (United States)

    Wang, David W.; Liu, Antony K.; Peng, Chih Y.; Meindl, Eric A.

    1994-01-01

    This paper presents a case study on the wave-current interaction near the local curvature of a Gulf Stream meander. The wave data were obtained from in situ measurements by a pitch-roll discus buoy during the Surface Wave Dynamics Experiment (SWADE) conducted off Wallops Island, Virginia, from October 1990 to March 1991. Owing to the advection of the Gulf Stream by the semidiurnal tide, the discus buoy was alternately located outside and inside the Gulf Stream. The directional wave measurements from the buoy show the changes in wave direction, wave energy, and directional spreading when waves encountered the current in the Gulf Stream meanders. A wave refraction model, using the ray-tracing method with an estimated Gulf Stream velocity field and meandering condition, was used to simulate wave refraction patterns and to estimate wave parameters at relative locations corresponding to buoy measurements. The numerical simulation shows that a focusing zone of wave rays was formed near the boundary and behind the crest of a simulated Gulf Stream meander. The focusing of wave rays causes changes in wave direction, increases in wave energy, and decreases in wave directional spreading, which are in good agreement with the results from the buoy measurements.

  11. Specific interactions of functionalised gold surfaces with ammonium perchlorate or starch; towards a chemical cartography of their mixture

    Science.gov (United States)

    Mercier, D.; Mercader, C.; Quere, S.; Hairault, L.; Méthivier, C.; Pradier, C. M.

    2012-10-01

    By functionalising gold samples, planar wafers or AFM tips, with an acid- or an amino acid-terminated thiols, mercaptoundecanoic acid (MUA) and homocystein (H-Cyst) respectively, we were able to differentiate the interactions with ammonium perchlorate (AP) and starch (S), two components of a nanocomposition mixture. To do so, the interaction between gold functionalized surfaces and the two targeted compounds have been characterized and quantified by several complementary techniques. Polarisation modulation-infrared spectroscopy (PM-IRRAS), and X-ray photoelectron spectroscopy (XPS), providing chemical analyses of gold surfaces after contacting S or AP, proved that both compounds were retained on MUA or H-Cyst-modified surfaces, but to various extents. Quartz crystal microbalance on-line measurements enabled to monitor the kinetics of interaction and showed distinct differences in the behaviour of MUA and H-Cyst-surfaces towards the two compounds. Having observed that only H-Cyst-modified surfaces enables to get a contrast on the chemical force microscopy (CFM) images, this new result could be well explained by examining the data obtained by combining the above-mentioned surface characterisation techniques.

  12. Effect of energy source, salt concentration and loading force on colloidal interactions between Acidithiobacillus ferrooxidans cells and mineral surfaces.

    Science.gov (United States)

    Diao, Mengxue; Nguyen, Tuan A H; Taran, Elena; Mahler, Stephen M; Nguyen, Anh V

    2015-08-01

    The surface appendages and extracellular polymeric substances of cells play an important role in the bacterial adhesion process. In this work, colloidal forces and nanomechanical properties of Acidithiobacillus ferrooxidans (A. f) interacted with silicon wafer and pyrite (FeS2) surfaces in solutions of varying salt concentrations were quantitatively examined using the bacterial probe technique with atomic force microscopy. A. f cells were cultured with either ferrous sulfate or elemental sulfur as key energy sources. Our results show that A. f cells grown with ferrous ion and elemental sulfur exhibit distinctive retraction force vs separation distance curves with stair-step and saw tooth shapes, respectively. During the approach of bacterial probes to the substrate surfaces, surface appendages and biopolymers of cells are sequentially compressed. The conformations of surface appendages and biopolymers are significantly influenced by the salt concentrations. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Interactions between metal ions and biogeo-surfaces in soil and water : basis for quantitative risk assessment

    NARCIS (Netherlands)

    Weng, L.P.

    2002-01-01

    To provide the basis for an improved quantitative risk assessment of heavy metals in the environment, the interactions between the metal ions and the biogeo-surfaces in soil and water were studied using both experimental and modelling approaches.

    The

  14. Binding Interactions Between alpha-glucans from Lactobacillus reuteri and Milk Proteins Characterised by Surface Plasmon Resonance

    NARCIS (Netherlands)

    Diemer, Silja K.; Svensson, Birte; Babol, Linnea N.; Cockburn, Darrell; Grijpstra, Pieter; Dijkhuizen, Lubbert; Folkenberg, Ditte M.; Garrigues, Christel; Ipsen, Richard H.

    Interactions between milk proteins and alpha-glucans at pH 4.0-5.5 were investigated by use of surface plasmon resonance. The alpha-glucans were synthesised with glucansucrase enzymes from Lactobacillus reuteri strains ATCC-55730, 180, ML1 and 121. Variations in the molecular characteristics of the

  15. Binding Interactions Between α-glucans from Lactobacillus reuteri and Milk Proteins Characterised by Surface Plasmon Resonance

    DEFF Research Database (Denmark)

    Diemer, Silja Kej; Svensson, Birte; Babol, Linnéa N.

    2012-01-01

    Interactions between milk proteins and α-glucans at pH 4.0–5.5 were investigated by use of surface plasmon resonance. The α-glucans were synthesised with glucansucrase enzymes from Lactobacillus reuteri strains ATCC-55730, 180, ML1 and 121. Variations in the molecular characteristics of the α...

  16. Surfaces of solids and their interactions with gaseous ambients. An introduction to the theory and experimental methods, with some examples

    International Nuclear Information System (INIS)

    Morgen, P.

    1977-10-01

    The physics and chemistry of ambient gases interacting with solid surfaces are discussed. The necessary theory and experimental techniques and apparatus used are described in detail. Results are presented for two semiconductor materials, silicon and zinc oxide. (W.D.L.)

  17. Aquatic flower-inspired cell culture platform with simplified medium exchange process for facilitating cell-surface interaction studies.

    Science.gov (United States)

    Hong, Hyeonjun; Park, Sung Jea; Han, Seon Jin; Lim, Jiwon; Kim, Dong Sung

    2016-02-01

    Establishing fundamentals for regulating cell behavior with engineered physical environments, such as topography and stiffness, requires a large number of cell culture experiments. However, cell culture experiments in cell-surface interaction studies are generally labor-intensive and time-consuming due to many experimental tasks, such as multiple fabrication processes in sample preparation and repetitive medium exchange in cell culture. In this work, a novel aquatic flower-inspired cell culture platform (AFIP) is presented. AFIP aims to facilitate the experiments on the cell-surface interaction studies, especially the medium exchange process. AFIP was devised to capture and dispense cell culture medium based on interactions between an elastic polymer substrate and a liquid medium. Thus, the medium exchange can be performed easily and without the need of other instruments, such as a vacuum suction and pipette. An appropriate design window of AFIP, based on scaling analysis, was identified to provide a criterion for achieving stability in medium exchange as well as various surface characteristics of the petal substrates. The developed AFIP, with physically engineered petal substrates, was also verified to exchange medium reliably and repeatedly. A closed structure capturing the medium was sustained stably during cell culture experiments. NIH3T3 proliferation results also demonstrated that AFIP can be applied to the cell-surface interaction studies as an alternative to the conventional method.

  18. Interactions between Vegetation and Land Surface Evolution in Arid and Semiarid Systems

    Science.gov (United States)

    Saco, P. M.; Willgoose, G.; Hancock, G.

    2004-12-01

    Ecological, hydrological and geomorphological processes are tightly coupled and the understanding of their complex interactions represents a research challenge that is at the heart of the emerging fields of ecohydrology and ecogeomorphology. The coupling between ecology and hydrology is particularly strong in drylands, in which water limited conditions are the main constraint for vegetation growth and survival. Arid and semiarid ecosystems comprise about 30% of the Earth's surface. Various forms of environmental perturbations like climate change and anthropogenic activities can lead to desertification or degradation of these ecosystems. The vegetation of water-limited ecosystems is commonly patterned, that is, arranged in a two phase mosaic composed of patches with high biomass cover interspersed within a low-cover or bare soil component. These patterns play an important role in controlling erosion. Human impacts or climate change may alter these systems, disrupting vegetation and triggering erosion. The resulting geomorphic changes are likely to have feedbacks including runaway desertification. Models that couple erosion and vegetation evolution can be used as a tool to understand the dynamics of arid and semi arid systems and the impact of climate change and human disturbance. However, the few existing models that explore the interactions between vegetation and sediment movement do not account for the feedbacks between ecohydrologic and geomorphic processes as is the objective of our research. A new modeling framework that couples the SIBERIA landform evolution model with a dynamic vegetation model for water limited ecosystems will be presented. The model explicitly accounts for the dynamics of runon-runoff areas that controls the evolution of the spatial distribution of vegetation in water limited ecosystems. The model reproduces the dynamics of banded vegetation patterns (tiger bush) characteristic of areas with mild slopes as well as more complex two

  19. Quantifying the regional groundwater/surface water interaction based on 18O and Deuterium

    Science.gov (United States)

    Merz, Christoph; Lischeid, Gunnar; Nitzsche, Kai; Kayler, Zachary Eric

    2017-04-01

    time. First results clearly show distinct patterns of the temporal dynamics of the groundwater/surface water interaction reflecting the regional system behavior. They provide the basis for anticipating future development of the hydraulic system under climate change, and - regarding system changes - for adapted water resources management decisions.

  20. Direct measurement of colloidal interactions between polyaniline surfaces in a UV-curable coating formulation: the effect of surface hydrophilicity/hydrophobicity and resin composition.

    Science.gov (United States)

    Jafarzadeh, Shadi; Claesson, Per M; Pan, Jinshan; Thormann, Esben

    2014-02-04

    The interactions between polyaniline particles and polyaniline surfaces in polyester acrylate resin mixed with 1,6-hexanediol diacrylate monomer have been investigated using contact angle measurements and the atomic force microscopy colloidal probe technique. Polyaniline with different characteristics (hydrophilic and hydrophobic) were synthesized directly on spherical polystyrene particles of 10 μm in diameter. Surface forces were measured between core/shell structured polystyrene/polyaniline particles (and a pure polystyrene particle as reference) mounted on an atomic force microscope cantilever and a pressed pellet of either hydrophilic or hydrophobic polyaniline powders, in resins of various polymer:monomer ratios. A short-range purely repulsive interaction was observed between hydrophilic polyaniline (doped with phosphoric acid) surfaces in polyester acrylate resin. In contrast, interactions between hydrophobic polyaniline (doped with n-decyl phosphonic acid) were dominated by attractive forces, suggesting less compatibility and higher tendency for aggregation of these particles in liquid polyester acrylate compared to hydrophilic polyaniline. Both observations are in agreement with the conclusions from the interfacial energy studies performed by contact angle measurements.

  1. Coastal Zone Hazards Related to Groundwater-Surface Water Interactions and Groundwater Flooding

    Science.gov (United States)

    Kontar, Y. A.; Ozorovich, Y. R.; Salokhiddinov, A. T.

    2009-12-01

    Worldwide, as many as half a million people have died in natural and man-made disasters since the turn of the 21st century (Wirtz, 2008). Further, natural and man-made hazards can lead to extreme financial losses (Elsner et al, 2009). Hazards, hydrological and geophysical risk analysis related to groundwater-surface water interactions and groundwater flooding have been to a large extent under-emphasized for coastal zone applications either due to economical limitations or underestimation of its significance. This is particularly true for tsunamis creating salt water intrusion to coastal aquifers, even though most tsunami hazard assessments have in the past relied on scenario or deterministic type models (Geist and Parsons, 2006), and to increasing mineralization of potable water because of intensive water diversions and also the abundance of highly toxic pollutants (mainly pesticides) in water, air and food, which contribute to the deterioration of the coastal population's health (Glantz, 2007). In the wake of pressing environmental and economic issues, it is of prime importance for the scientific community to shed light onto the great efforts by hydrologists and geophysicists to quantify conceptual uncertainties and to provide quality assurances of potential coastal zone hazard evaluation and prediction. This paper proposes consideration of two case studies which are important and significant for future development and essential for feasibility studies of hazards in the coastal zone. The territory of the Aral Sea Region in Central Asia is known as an ecological disaster coastal zone (Zavialov, 2005). It is now obvious that, in order to provide reasonable living conditions to the coastal zone population, it is first of all necessary to drastically improve the quality of the water dedicated to human needs. Due to their intensive pollution by industrial wastes and by drainage waters from irrigated fields, the Syr Darya and Amu Darya rivers can no longer be considered

  2. Interactions between multiple filaments and bacterial biofilms on the surface of an apple

    Science.gov (United States)

    He, CHENG; Maoyuan, XU; Shuhui, PAN; Xinpei, LU; Dawei, LIU

    2018-04-01

    In this paper, the interactions between two dielectric barrier discharge (DBD) filaments and three bacterial biofilms are simulated. The modeling of a DBD streamer is studied by means of 2D finite element calculation. The model is described by the proper governing equations of air DBD at atmospheric pressure and room temperature. The electric field in the computing domain and the self-consistent transportation of reactive species between a cathode and biofilms on the surface of an apple are realized by solving a Poisson equation and continuity equations. The electron temperature is solved by the electron energy conservation equation. The conductivity and permittivity of bacterial biofilms are considered, and the shapes of the bacterial biofilms are irregular in the uncertainty and randomness of colony growth. The distribution of the electrons suggests that two plasma channels divide into three plasma channels when the streamer are 1 mm from the biofilms. The toe-shapes of the biofilms and the simultaneous effect of two streamer heads result in a high electric field around the biofilms, therefore the stronger ionization facilitates the major part of two streamers combined into one streamer and three streamers arise. The distribution of the reactive oxygen species and the reactive nitrogen species captured by time fluences are non-uniform due to the toe-shaped bacterial biofilms. However, the plasma can intrude into the cavities in the adjacent biofilms due to the μm-scale mean free path. The two streamers case has a larger treatment area and realizes the simultaneous treatment of three biofilms compared with one streamer case.

  3. Ion-nanostructure interaction. Comparing simulation and experiment towards surface structuring using nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Holland-Moritz, Henry

    2016-10-18

    Nanotechnology is a buzzword in context of the proceeding miniaturization of devices and their components. Nanoparticles (NPs) can nowadays easily be synthesized from different material compositions by different chemical and physical processes. However, most of these techniques work close to or at the thermal equilibrium. One subsequent approach to tune materials beyond equilibrium conditions is ion beam irradiation. An important effect of this approach is sputtering. Sputtering is enhanced in NPs compared to their bulk counterparts due to their large surface-to-volume ratio, especially when the ion range matches the NP size. In this work, the sputtering effects of Ar{sup +} and Ga{sup +} ion irradiated Au nanoparticles are investigated in detail by Monte Carlo (MC) and molecular dynamics (MD) simulations and a variety of experiments. The sputtering of Ar{sup +} and Ga{sup +} irradiated Au NPs was investigated as a function of ion energy, NP size and impact parameter by the MC code iradina and MD code parcas. The simulation results are directly compared to experiments using high resolution scanning electron microscopy (SEM) of Au NPs on top of Si, whereat the sputter yields are significantly enhanced compared to the MC simulations. Additionally, the interaction of NPs and substrate were investigated by Rutherford backscatter spectrometry (RBS), atomic force microscopy (AFM) and scanning transmission electron microscopy (STEM). A new MC code was developed to study the redeposition of sputtered atoms of Ga{sup +} irradiated Au NP arrays on neighboring NPs. The redeposition can lead to growth of NPs with diameters of 1 nm in vicinity of ∝50 nm NP. These simulations are directly compared to an in situ experiment. Nanostructures, spherical NPs as well as nanowires (NWs) are used as irradiation masks to structure lithium niobate (LNO) using the ion beam enhanced etching (IBEE) technique. The aspect ratio of the obtained structures can be enhanced by a second IBEE step

  4. Probing Sub-GeV Mass Strongly Interacting Dark Matter with a Low-Threshold Surface Experiment.

    Science.gov (United States)

    Davis, Jonathan H

    2017-11-24

    Using data from the ν-cleus detector, based on the surface of Earth, we place constraints on dark matter in the form of strongly interacting massive particles (SIMPs) which interact with nucleons via nuclear-scale cross sections. For large SIMP-nucleon cross sections, the sensitivity of traditional direct dark matter searches using underground experiments is limited by the energy loss experienced by SIMPs, due to scattering with the rock overburden and experimental shielding on their way to the detector apparatus. Hence, a surface-based experiment is ideal for a SIMP search, despite the much larger background resulting from the lack of shielding. We show using data from a recent surface run of a low-threshold cryogenic detector that values of the SIMP-nucleon cross section up to approximately 10^{-27}  cm^{2} can be excluded for SIMPs with masses above 100 MeV.

  5. The interaction of oxygen and carbon monoxide with a carbided Ni(111) surface

    NARCIS (Netherlands)

    Geus, John W.; Vink, T.J.; Zandvoort, M.M.J. van; Gijzeman, O.L.J.

    1984-01-01

    The thermal decomposition of ethylene on Ni(111) at 250°C is shown to lead to carbon deposition on and - in a later stage - below the surface. Independent of the amount of carbon below the surface, CO is adsorbed with an isosteric heat of adsorption of 105 kJ/mol. The surface carbon reacts with

  6. Atomic forces between noble gas atoms, alkali ions, and halogen ions for surface interactions

    Science.gov (United States)

    Wilson, J. W.; Outlaw, R. A.; Heinbockel, J. H.

    1988-01-01

    The components of the physical forces between noble gas atoms, alkali ions, and halogen ions are analyzed and a data base developed from analysis of the two-body potential data, the alkali-halide molecular data, and the noble gas crystal and salt crystal data. A satisfactory global fit to this molecular and crystal data is then reproduced by the model to within several percent. Surface potentials are evaluated for noble gas atoms on noble gas surfaces and salt crystal surfaces with surface tension neglected. Within this context, the noble gas surface potentials on noble gas and salt crystals are considered to be accurate to within several percent.

  7. Interactions of satellite-speed helium atoms with satellite-surfaces. 1. Spatial distributions of reflected helium atoms

    International Nuclear Information System (INIS)

    Liu, S.M.; Rodgers, W.E.; Knuth, E.L.

    1975-06-01

    Interactions of satellite-speed helium atoms with practical satellite surfaces were investigated experimentally, and spatial distributions of satellite-speed helium beams scattered from four different engineering surfaces were measured. The 7000-m/s helium beams were produced using an arc-heated supersonic molecular beam source. The test surfaces included cleaned 6061-T6 aluminum plate, anodized aluminum foil, white paint, and quartz surfaces. Both in-plane (in the plane containing the incident beam and the surface normal) and out-of-plane spatial distributions of reflected helium atoms were measured for six different incidence angles (0, 15, 30, 45, 60, and 75 deg from the surface normal). It was found that a large fraction of the incident helium atoms were scattered back in the vicinity of the incoming beam, particularly in the case of glancing incidence angles. This unexpected scattering feature results perhaps from the gross roughness of these test surfaces. This prominent backscattering could yield drag coefficients which are higher than for surfaces with either forward-lobed or diffusive (cosine) scattering patterns

  8. Surface-supported Ag islands stabilized by a quantum size effect: Their interaction with small molecules relevant to ethylene epoxidation

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Dahai [Iowa State Univ., Ames, IA (United States)

    2013-05-15

    This dissertation focuses on how QSE-stabilized, surface-supported Ag nanoclusters will interact with ethylene or oxygen. Experiments are performed to determine whether the QSE-mediated Ag islands react differently toward adsorption of ethylene or oxygen, or whether the adsorption of these small molecules will affect the QSE-mediated stability of Ag islands. Studies of the interaction of oxygen with Ag/Si(111)-7×7 were previously reported, but these studies were performed at a low Ag coverage where 3D Ag islands were not formed. So the study of such a system at a higher Ag coverage will be a subject of this work. The interaction of ethylene with Ag/Si(111)-7×7, as well as the interaction of oxygen with Ag/NiAl(110) are also important parts of this study.

  9. Positive Charges on the Surface of Thaumatin Are Crucial for the Multi-Point Interaction with the Sweet Receptor.

    Science.gov (United States)

    Masuda, Tetsuya; Kigo, Satomi; Mitsumoto, Mayuko; Ohta, Keisuke; Suzuki, Mamoru; Mikami, Bunzo; Kitabatake, Naofumi; Tani, Fumito

    2018-01-01

    Thaumatin, an intensely sweet-tasting protein, elicits sweet taste with a threshold of only 50 nM. Previous studies from our laboratory suggested that the complex model between the T1R2-T1R3 sweet receptor and thaumatin depends critically on the complementarity of electrostatic potentials. In order to further validate this model, we focused on three lysine residues (Lys78, Lys106, and Lys137), which were expected to be part of the interaction sites. Three thaumatin mutants (K78A, K106A, and K137A) were prepared and their threshold values of sweetness were examined. The results showed that the sweetness of K106A was reduced by about three times and those of K78A and K137A were reduced by about five times when compared to wild-type thaumatin. The three-dimensional structures of these mutants were also determined by X-ray crystallographic analyses at atomic resolutions. The overall structures of mutant proteins were similar to that of wild-type but the electrostatic potentials around the mutated sites became more negative. Since the three lysine residues are located in 20-40 Å apart each other on the surface of thaumatin molecule, these results suggest the positive charges on the surface of thaumatin play a crucial role in the interaction with the sweet receptor, and are consistent with a large surface is required for interaction with the sweet receptor, as proposed by the multipoint interaction model named wedge model.

  10. A new insight into the interaction of ZnO with calf thymus DNA through surface defects.

    Science.gov (United States)

    Das, Sumita; Chatterjee, Sabyasachi; Pramanik, Srikrishna; Devi, Parukuttyamma Sujatha; Kumar, Gopinatha Suresh

    2018-01-01

    Experimental evidences on the binding interaction of ZnO and Calf Thymus (CT) DNA using several biophysical techniques are the centre of interest of the present study. The interaction of ZnO with CT DNA has been investigated in detail by absorption spectral study, fluorescence titration, Raman analysis, zeta potential measurement, viscometric experiment along with thermal melting study and microscopic analysis. Steady-state fluorescence study revealed the quenching (48%) of the surface defect related peak intensity of ZnO on interaction with DNA. The optimized concentration of ZnO and DNA to obtain this level of quenching has been found to be 0.049mM and 1.027μM, respectively. Additional fluorescence study with 8-hydroxy-5-quinoline (HQ) as a fluorescence probe for Zn 2+ ruled out the dissolution effect of ZnO under the experimental conditions. DNA conjugation on the surface of ZnO was also supported by Raman study. The quantitative variation in conductivity as well as electrophoretic mobility indicated significant interaction of ZnO with the DNA molecule. Circular dichroism (CD) and viscometry titrations provided clear evidence in support of the conformational retention of the DNA on interaction with ZnO. The binding interaction was found to be predominantly entropy driven in nature. The bio-physical studies presented in this paper exploring ZnO-CT DNA interaction could add a new horizon to understand the interaction between metal oxide and DNA. Copyright © 2017. Published by Elsevier B.V.

  11. Interaction of the human body and surfaces of different stiffness during drop jumps.

    Science.gov (United States)

    Arampatzis, Adamantios; Stafilidis, Savvas; Morey-Klapsing, Gaspar; Brüggemann, Gert-peter

    2004-03-01

    The purpose of this study was to examine two hypotheses: (a) the stiffness of the surface influences the leg stiffness of the subjects during drop jumps, and (b) drop jumping performance (jumping height and energy rates of the subject's center of mass during the contact phase) increases when decreasing surface stiffness due to a greater energy storage capacity of the surface for a given acting force. Ten female subjects performed a series of drop jumps from 40-cm height onto two sprung surfaces with different stiffness. Those trials of each subject displaying the maximal mechanical power during the upward phase were analyzed. The ground reaction forces were measured using a force plate. Sagittal kinematics of the subject's body positions and the deformation of the surface were recorded using two high-speed video cameras. On the soft surface, the jumping height and the energy rates of the subjects during the contact phase were greater than on the hard one. The energy delivered by the subjects during the upward phase, the leg and joint stiffness, as well as the range of motion of the subjects remained unchanged for both surfaces. The absolute energy loss is lower for the hard surface, but the jumping performance is greater for the soft one. The reason is a higher ratio of positive to negative mechanical work done by the subjects during the contact phase. The adjustment of the subjects to different surfaces is not only dependent on the stiffness of the surface but also on the intensity of the movement.

  12. Study of the interaction of liquid with the surface of mass standards of high accuracy stainless steel

    International Nuclear Information System (INIS)

    Ramirez Varas, Lautaro; Castro, Claudio S.C.; Cacais, Fabio L.; Pires, Manoel J. M.; Loayza Mendoza, Victor M.

    2011-01-01

    The long term stability of mass standards depends on the interaction between the surface and environment molecules. From this point of view, a study was investigated of the effect on stainless steel surfaces by liquids frequently used in hydrostatic weighing (FC40) and in cleaning procedures of mass standards (isopropyl alcohol). Firstly, mass weighing difference was measured as function of time with a gravimetric method. Additionally, stainless steel samples were analyzed by X-ray Photoelectron Spectroscopy (XPS). The standard used for the gravimetric mass difference determination was immersed in FC40. The samples analyzed by XPS were previously immersed in both FC40 and isopropyl alcohol. Mass differences were obtained with an uncertainty of 1 μg when FC40 was used. Preliminary results have suggested that FC40 is not chemically bound to stainless steel surfaces and the mass gain was due to physisorbed molecules on the surface. (author) [es

  13. Modeling the Surface Water-Groundwater Interaction in Arid and Semi-Arid Regions Impacted by Agricultural Activities

    Science.gov (United States)

    Tian, Y.; Wu, B.; Zheng, Y.

    2013-12-01

    In many semi-arid and arid regions, interaction between surface water and groundwater plays an important role in the eco-hydrological system. The interaction is often complicated by agricultural activities such as surface water diversion, groundwater pumping, and irrigation. In existing surface water-groundwater integrated models, simulation of the interaction is often simplified, which could introduce significant simulation uncertainty under certain circumstance. In this study, GSFLOW, a USGS model coupling PRMS and MODFLOW, was improved to better characterize the surface water-groundwater interaction. The practices of water diversion from rivers, groundwater pumping and irrigation are explicitly simulated. In addition, the original kinematic wave routing method was replaced by a dynamic wave routing method. The improved model was then applied in Zhangye Basin (the midstream part of Heihe River Baisn), China, where the famous 'Silk Road' came through. It is a typical semi-arid region of the western China, with extensive agriculture in its oasis. The model was established and calibrated using the data in 2000-2008. A series of numerical experiments were conducted to evaluate the effect of those improvements. It has been demonstrated that with the improvements, the observed streamflow and groundwater level were better reproduced by the model. The improvements have a significant impact on the simulation of multiple fluxes associated with the interaction, such as groundwater discharge, riverbed seepage, infiltration, etc. Human activities were proved to be key elements of the water cycle in the study area. The study results have important implications to the water resources modeling and management in semi-arid and arid basins.

  14. Single NdPc2 molecules on surfaces. Adsorption, interaction, and molecular magnetism

    International Nuclear Information System (INIS)

    Fahrendorf, Sarah

    2013-01-01

    They have huge potential for application in molecular-spin-transistors, molecular-spinvalves, and molecular quantum computing. SMMs are characterized by high spin ground states with zero-field splitting leading to high relaxation barriers and long relaxation times. A relevant class of molecules are the lanthanide double-decker phthalocyanines (LaPc 2 ) with only one metal atom sandwiched between two organic phthalocyanine (Pc) ligands. For envisaged spintronic applications it is important to understand the interaction between the molecules and the substrate and its influence on the electronic and magnetic properties. The subject of this thesis is the investigation of the adsorbed neodymium double-decker phthalocyanine (NdPc 2 ) by means of low temperature scanning tunneling microscopy and spectroscopy (STM and STS). The molecules are deposited by sublimation onto different substrates. It is observed that a large fraction of the double-decker molecules decomposes during deposition. The decomposition probability strongly depends on the chosen substrate. Therefore it is concluded that the substrate modifies the electronic structure of the molecule leading to a stabilization or destabilization of the molecular entity. Charge transfer from the surface to the molecule is identified as a potential stabilizing mechanism. The electronic and magnetic properties are investigated in detail for adsorbed NdPc 2 molecules on Cu(100). The results of the experimental study are compared to state-of-the-art density functional theory calculations performed by our colleagues from the Peter Gruenberg Institute (PGI-1) at the Forschungszentrum Juelich. Interestingly, the lower Pc ring of the molecule hybridizes intensely with the substrate leading to strong chemisorption of the molecule, while the upper Pc ring keeps its molecular type electronic states, which can be energetically shifted by an external electric field. Importantly, it is possible to get direct access to the spin

  15. Single NdPc{sub 2} molecules on surfaces. Adsorption, interaction, and molecular magnetism

    Energy Technology Data Exchange (ETDEWEB)

    Fahrendorf, Sarah

    2013-01-24

    They have huge potential for application in molecular-spin-transistors, molecular-spinvalves, and molecular quantum computing. SMMs are characterized by high spin ground states with zero-field splitting leading to high relaxation barriers and long relaxation times. A relevant class of molecules are the lanthanide double-decker phthalocyanines (LaPc{sub 2}) with only one metal atom sandwiched between two organic phthalocyanine (Pc) ligands. For envisaged spintronic applications it is important to understand the interaction between the molecules and the substrate and its influence on the electronic and magnetic properties. The subject of this thesis is the investigation of the adsorbed neodymium double-decker phthalocyanine (NdPc{sub 2}) by means of low temperature scanning tunneling microscopy and spectroscopy (STM and STS). The molecules are deposited by sublimation onto different substrates. It is observed that a large fraction of the double-decker molecules decomposes during deposition. The decomposition probability strongly depends on the chosen substrate. Therefore it is concluded that the substrate modifies the electronic structure of the molecule leading to a stabilization or destabilization of the molecular entity. Charge transfer from the surface to the molecule is identified as a potential stabilizing mechanism. The electronic and magnetic properties are investigated in detail for adsorbed NdPc{sub 2} molecules on Cu(100). The results of the experimental study are compared to state-of-the-art density functional theory calculations performed by our colleagues from the Peter Gruenberg Institute (PGI-1) at the Forschungszentrum Juelich. Interestingly, the lower Pc ring of the molecule hybridizes intensely with the substrate leading to strong chemisorption of the molecule, while the upper Pc ring keeps its molecular type electronic states, which can be energetically shifted by an external electric field. Importantly, it is possible to get direct access to the

  16. Surface-atmosphere interactions with coupled within-canopy aerodynamic resistance and canopy reflection.

    Science.gov (United States)

    Timmermans, J.; van der Tol, C.; Verhoef, W.; Su, Z.

    2009-04-01

    Models that describe the exchange of CO2 and H2O between the surface and atmosphere use bulk-parametrization of the within-canopy aerodynamic resistance and leaf area density (eq. LAI). This bulk parametrization is based on the Monin-Obukhov Similarity (MOS) theory. The MOS theory however breaks down for sparse canopies and it cannot couple profiles in the leaf density to profiles in the within-canopy aerodynamic resistance. The objective of this research is to create a simple model that is able to couple the within-canopy aerodynamic resistance and canopy reflection for different levels in the canopy. This model should be able to represent the canopy using as fewer parameters as possible, in order to facilitate inversion of remote sensing imagery. A virtual canopy was simulated using an L-systems approach, Lindenmayer 1968. The L-system approach was chosen because it describes the canopy with fractals. It therefore needs very little inputs to simulate a virtual canopy. A vertical profile of leaf density was calculated for 60 levels from this virtual canopy. The within-canopy aerodynamic resistance was modeled from the vertical leaf density profile using foliage drag coefficient, Massman 1997. A modified version of the SCOPE (Soil Canopy Observations and Photosynthesis) model was used to calculate the H2O and CO2 fluxes using the vertical profiles of leaf density and within-canopy aerodynamic resistance. The simulated fluxes are compared with field measurements over a vineyard and a forested area. The field measurements in both areas are acquired using the same setup: a basic flux tower in addition with an eddy-covariance setup. We present in this article the methodology and the results, as a proof of concept. references Massman, W.J., An Analytical One-Dimensional Model of Momentum Transfer by vegetation of arbitrary structure, Boundary-Layer Meteorology, 1997, 83, 407-421 Lindenmayer, A., Mathematical Models for Cellular Interactions in Development, Journal of

  17. Interaction of progenitor bone cells with different surface modifications of titanium implant

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wen-Cheng, E-mail: wencchen@fcu.edu.tw [Advanced Medical Devices and Composites Laboratory, Department of Fiber and Composite Materials, College of Engineering, Feng Chia University, Taichung 40724, Taiwan (China); Chen, Ya-Shun [Advanced Medical Devices and Composites Laboratory, Department of Fiber and Composite Materials, College of Engineering, Feng Chia University, Taichung 40724, Taiwan (China); Ko, Chia-Ling [Advanced Medical Devices and Composites Laboratory, Department of Fiber and Composite Materials, College of Engineering, Feng Chia University, Taichung 40724, Taiwan (China); Dental Medical Devices and Materials Research Center, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China); Lin, Yi; Kuo, Tzu-Huang; Kuo, Hsien-Nan [Medical Device Development Division, Metal Industries Research and Development Centre, Kaohsiung 82151, Taiwan (China)

    2014-04-01

    Changes in the physical and chemical properties of Ti surfaces can be attributed to cell performance, which improves surface biocompatibility. The cell proliferation, mineralization ability, and gene expression of progenitor bone cells (D1 cell) were compared on five different Ti surfaces, namely, mechanical grinding (M), electrochemical modification through potentiostatic anodization (ECH), sandblasting and acid etching (SLA), sandblasting, hydrogen peroxide treatment, and heating (SAOH), and sandblasting, alkali heating, and etching (SMART). SAOH treatment produced the most hydrophilic surface, whereas SLA produced the most hydrophobic surface. Cell activity indicated that SLA and SMART produced significantly rougher surfaces and promoted D1 cell attachment within 1 day of culturing, whereas SAOH treatment produced moderate roughness (Ra = 1.26 μm) and accelerated the D1 cell proliferation up to 7 days after culturing. The ECH surface significantly promoted alkaline phosphatase (ALP) expression and osteocalcin (OCN) secretion in the D1 cells compared with the other surface groups. The ECH and SMART-treated Ti surfaces resulted in maximum ALP and OCN expressions during the D1 cell culture. SLA, SAOH, and SMART substrate surfaces were rougher and exhibited better cell metabolic responses during the early stage of cell attachment, proliferation, and morphologic expressions within 1 day of D1 cell culture. The D1 cells cultured on the ECH and SMART substrates exhibited higher differentiation, and higher ALP and OCN expressions after 10 days of culture. Thus, the ECH and SMART treatments promote better ability of cell mineralization in vitro, which demonstrate their great potential for clinical use. - Highlights: • Progenitor bone cells onto Ti with different modifications are characterized. • Surface roughness and hydrophilicity encourage early stage cell attachment. • Composition and surface treatments are more vital in bone cell mineralization.

  18. Interaction of dense nitrogen plasma with SS304 surface using APF plasma focus device

    Science.gov (United States)

    Afrashteh, M.; Habibi, M.; Heydari, E.

    2012-04-01

    The nitridation of SS304 surfaces is obtained by irradiating nitrogen ions from Amirkabir plasma focus device, which use multiple focus deposition shots at optimum distance 10 cm from the anode. The Vickers Micro-Hardness values are improved more than twice for the nitrided samples comparing to the nonnitrided ones. The X-ray diffraction (XRD) analysis is carried out in order to explore the phase changes in the near surface structure of the metals. The results of Scanning Electron Microscopy (SEM) indicate changes in surface morphology which are the emergence of smooth and uniform film on the surface of the nitrided metals.

  19. Target surface area effects on hot electron dynamics from high intensity laser-plasma interactions

    Science.gov (United States)

    Zulick, C.; Raymond, A.; McKelvey, A.; Chvykov, V.; Maksimchuk, A.; Thomas, A. G. R.; Willingale, L.; Yanovsky, V.; Krushelnick, K.

    2016-06-01

    Reduced surface area targets were studied using an ultra-high intensity femtosecond laser in order to determine the effect of electron sheath field confinement on electron dynamics. X-ray emission due to energetic electrons was imaged using a {K}α imaging crystal. Electrons were observed to travel along the surface of wire targets, and were slowed mainly by the induced fields. Targets with reduced surface areas were correlated with increased hot electron densities and proton energies. Hybrid Vlasov-Fokker-Planck simulations demonstrated increased electric sheath field strength in reduced surface area targets.

  20. Atmosphere-surface interactions on Venus and implications for atmospheric evolution

    International Nuclear Information System (INIS)

    Khodakovsky, I.L.

    1982-01-01

    The physico-chemical processes controlling the Venusian tropospheric chemical composition surface rock mineral assemblages and volatile element distribution in the atmosphere and planetary crust is considered. (author)

  1. Interaction of H2 with simple metal surfaces - A model based on the anisotropic effective medium theory

    Science.gov (United States)

    Karimi, M.; Ila, D.; Dalins, I.; Vidali, G.

    1990-01-01

    Calculations are presented for the interaction of H2 with surfaces of Cu, Ag, Au and Al. The repulsive part of the potential is evaluated using the results of anisotropic effective medium theory (AEMT) while the attractive part is calculated from anisotropic damped dipole-dipole and damped dipole-quadrupole interactions. The model does not have any fitting parameters and its predictions are in excellent agreement with the available experimental data. The anisotropy of H2 is included in the model but our results show that this effect is very small.

  2. Multifunctional ultra-high vacuum apparatus for studies of the interactions of chemical warfare agents on complex surfaces.

    Science.gov (United States)

    Wilmsmeyer, Amanda R; Gordon, Wesley O; Davis, Erin Durke; Mantooth, Brent A; Lalain, Teri A; Morris, John R

    2014-01-01

    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.

  3. First-principles surface interaction studies of aluminum-copper and aluminum-copper-magnesium secondary phases in aluminum alloys

    Science.gov (United States)

    da Silva, Thiago H.; Nelson, Eric B.; Williamson, Izaak; Efaw, Corey M.; Sapper, Erik; Hurley, Michael F.; Li, Lan

    2018-05-01

    First-principles density functional theory-based calculations were performed to study θ-phase Al2Cu, S-phase Al2CuMg surface stability, as well as their interactions with water molecules and chloride (Cl-) ions. These secondary phases are commonly found in aluminum-based alloys and are initiation points for localized corrosion. Density functional theory (DFT)-based simulations provide insight into the origins of localized (pitting) corrosion processes of aluminum-based alloys. For both phases studied, Cl- ions cause atomic distortions on the surface layers. The nature of the distortions could be a factor to weaken the interlayer bonds in the Al2Cu and Al2CuMg secondary phases, facilitating the corrosion process. Electronic structure calculations revealed not only electron charge transfer from Cl- ions to alloy surface but also electron sharing, suggesting ionic and covalent bonding features, respectively. The S-phase Al2CuMg structure has a more active surface than the θ-phase Al2Cu. We also found a higher tendency of formation of new species, such as Al3+, Al(OH)2+, HCl, AlCl2+, Al(OH)Cl+, and Cl2 on the S-phase Al2CuMg surface. Surface chemical reactions and resultant species present contribute to establishment of local surface chemistry that influences the corrosion behavior of aluminum alloys.

  4. H2 INTERACTION WITH BIMETALLIC DIMERS SUPPORTED ON THE MgO(100) SURFACE: A DFT CLUSTER MODEL STUDY

    OpenAIRE

    PIOTR MATCZAK

    2012-01-01

    The interaction between the H2 molecule and the PdAg, PdAu, PtAg and PtAu bimetallic dimers deposited on the MgO(100) surface is investigated using density functional theory (DFT). The bimetallic dimers, whose molecular axes are considered to be perpendicular to the support surface, are adsorbed on top of an oxygen atom. Within this adsorption mode, the dimers prefer the orientation in which their Pd or Pt end is closer to the oxygen atom. The Ag and Au ends of the MgO-supported dimers captur...

  5. Nonexponential decay of velocity correlations in surface diffusion: The role of interactions and ordering

    DEFF Research Database (Denmark)

    Vattulainen, Ilpo Tapio; Hjelt, T.; Ala-Nissila, T.

    2000-01-01

    We study the diffusive dynamics of adparticles in two model systems with strong interactions by considering the decay of the single-particle velocity correlation function phi (t). In accordance with previous studies, we find phi (t) to decay nonexponentially and follow a power-law phi (t)similar ......We study the diffusive dynamics of adparticles in two model systems with strong interactions by considering the decay of the single-particle velocity correlation function phi (t). In accordance with previous studies, we find phi (t) to decay nonexponentially and follow a power-law phi (t...... be rationalized in terms of interaction effects. Namely, x is typically larger than two in cases where repulsive adparticle-adparticle interactions dominate, while attractive interactions lead to x...

  6. Experimental studies of O2-SnO2 surface interaction using powder, thick films and monocrystalline thin films

    International Nuclear Information System (INIS)

    Saukko, S.; Lassi, Ulla; Lantto, V.; Kroneld, M.; Novikov, S.; Kuivalainen, P.; Rantala, T.T.; Mizsei, J.

    2005-01-01

    Surface properties of solids and the interactions between molecules and solid surfaces are important for many technical applications. They also involve a range of physical and chemical phenomena of fundamental scientific interest. The importance of oxygen chemistry at SnO 2 surfaces follows from the fact that SnO 2 is used as an active material in gas sensor applications. The operation principle of these sensors is usually based on measurable conductance response of the material, which is understood in terms of reactions of gas molecules with different oxygen species adsorbed onto the surface. The role of the lattice oxygen, but in particular, the bridging oxygen atoms on SnO 2 surfaces, is also active. Detailed understanding of the reaction mechanisms of various oxygen species at SnO 2 surfaces is important, as it offers a way to improve the sensitivity and selectivity of the sensors. Oxygen adsorption-desorption kinetics at the SnO 2 surface is studied experimentally using O 2 -temperature-programmed desorption (TPD) method together with conductance measurements in the case of SnO 2 powder and polycrystalline thick films made from the powder. In addition, CO-TPD is studied and the transient behaviour of various oxygen species is considered. Molecular beam epitaxy (MBE) was also used to fabricate polycrystalline and monocrystalline thin films with the SnO 2 (101) face on single crystal sapphire substrate. Simultaneous surface potential and conductance measurements during heating and cooling in different ambient atmospheres were used to characterize the monocrystalline SnO 2 (101) surface after various surface treatments

  7. Selective interaction of heparin with the variable region 3 within surface glycoprotein of laboratory-adapted feline immunodeficiency virus.

    Science.gov (United States)

    Hu, Qiong-Ying; Fink, Elizabeth; Grant, Chris K; Elder, John H

    2014-01-01

    Heparan sulfate proteoglycans (HSPG) can act as binding receptors for certain laboratory-adapted (TCA) strains of feline immunodeficiency virus (FIV) and human immunodeficiency virus (HIV). Heparin, a soluble heparin sulfate (HS), can inhibit TCA HIV and FIV entry mediated by HSPG interaction in vitro. In the present study, we further determined the selective interaction of heparin with the V3 loop of TCA of FIV. Our current results indicate that heparin selectively inhibits infection by TCA strains, but not for field isolates (FS). Heparin also specifically interferes with TCA surface glycoprotein (SU) binding to CXCR4, by interactions with HSPG binding sites on the V3 loop of the FIV envelope protein. Peptides representing either the N- or C-terminal side of the V3 loop and containing HSPG binding sites were able to compete away the heparin block of TCA SU binding to CXCR4. Heparin does not interfere with the interaction of SU with anti-V3 antibodies that target the CXCR4 binding region or with the interaction between FS FIV and anti-V3 antibodies since FS SU has no HSPG binding sites within the HSPG binding region. Our data show that heparin blocks TCA FIV infection or entry not only through its competition of HSPG on the cell surface interaction with SU, but also by its interference with CXCR4 binding to SU. These studies aid in the design and development of heparin derivatives or analogues that can inhibit steps in virus infection and are informative regarding the HSPG/SU interaction.

  8. Selective interaction of heparin with the variable region 3 within surface glycoprotein of laboratory-adapted feline immunodeficiency virus.

    Directory of Open Access Journals (Sweden)

    Qiong-Ying Hu

    Full Text Available Heparan sulfate proteoglycans (HSPG can act as binding receptors for certain laboratory-adapted (TCA strains of feline immunodeficiency virus (FIV and human immunodeficiency virus (HIV. Heparin, a soluble heparin sulfate (HS, can inhibit TCA HIV and FIV entry mediated by HSPG interaction in vitro. In the present study, we further determined the selective interaction of heparin with the V3 loop of TCA of FIV. Our current results indicate that heparin selectively inhibits infection by TCA strains, but not for field isolates (FS. Heparin also specifically interferes with TCA surface glycoprotein (SU binding to CXCR4, by interactions with HSPG binding sites on the V3 loop of the FIV envelope protein. Peptides representing either the N- or C-terminal side of the V3 loop and containing HSPG binding sites were able to compete away the heparin block of TCA SU binding to CXCR4. Heparin does not interfere with the interaction of SU with anti-V3 antibodies that target the CXCR4 binding region or with the interaction between FS FIV and anti-V3 antibodies since FS SU has no HSPG binding sites within the HSPG binding region. Our data show that heparin blocks TCA FIV infection or entry not only through its competition of HSPG on the cell surface interaction with SU, but also by its interference with CXCR4 binding to SU. These studies aid in the design and development of heparin derivatives or analogues that can inhibit steps in virus infection and are informative regarding the HSPG/SU interaction.

  9. Interaction of small hydrocarbon ions and Ar(+) with carbon-fibre-composite surfaces at room temperature