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Sample records for au111 surfaces addressed

  1. Au(111) and Pt(111) surface phase behavior

    Sandy, A.R.; Mochrie, S.G.J.; Zehner, D.M.

    1993-01-01

    We describe our recent X-ray scattering studies of the structure and phases of the clean Au(111) and Pt(111) surfaces. Below 0.65 of their respective bulk melting temperatures, the Au(111) surface has a well-ordered chevron reconstruction and the Pt(111) surface is unreconstructed. Above these te......We describe our recent X-ray scattering studies of the structure and phases of the clean Au(111) and Pt(111) surfaces. Below 0.65 of their respective bulk melting temperatures, the Au(111) surface has a well-ordered chevron reconstruction and the Pt(111) surface is unreconstructed. Above...

  2. Carbon monoxide oxidation on bimetallic Ru/Au(111 surfaces

    ROLF-JÜRGEN BEHM

    2001-02-01

    Full Text Available The electrochemical deposition of Ru on Au(111 was performed in 0.5 M H2SO4+10-4 M RuCl3 . The obtained bimetallic Ru/Au(111 surfaces were character-ised by cyclic voltammetry and in situ STM in 0.5 MH2SO4. The Ru deposit consists of nanoscale islands, which merge with increasing coverage. Two different types of bimetallic Ru/Au(111 surfaces with respect to the distribution of Ru islands over the Au(111 substrate surface were obtained. When the deposition was performed at potentials more positive than the range of Au(111 reconstruction, homogeneous nucleation occured resulting in a random distribution of Ru islands. When the deposition was performed on reconstructed Au(111 at low overpotentials, selective nucleation occured resulting in the replication of the Au(111 reconstruction. Only at higher deposition overpotentials, can multilayer deposits be formed, which exhibit a very rough surface morphology. The electrocatalytic activity of such structurally well defined Ru/Au(111 bimetallic surfaces was studied towards CO oxidation with the Ru coverage ranging from submonolayer to several monolayer. COstripping commences at about 0.2 Vand occurs over a broad potential range. The observed influence of the Ru structure on the CO stripping voltammetry is explained by local variations in the COadsorption energy, caused by differences in the local Ru structure and by effects induced by the Au(111 substrate.

  3. Structure investigation of organic molecules on Au(111) surfaces; Strukturuntersuchung organischer Molekuele auf Au(111)-Oberflaechen

    Kazempoor, Michel

    2009-02-02

    The present work covers two topics namely the coadsorption of formic acid and water on Au(111) and the structure of biphenylalkanthiole SAMs on Au(111) surfaces. The coadsorption of formic acid and water on Au(111) surfaces has been investigated by means of vibrational and photoelectron spectroscopy (HREELS, XPS). Formic acid adsorbs at 90 K molecularly with vibrational modes characteristic for flat lying zig-zag chains in the mono- and multilayer regime, like in solid formic acid. The structure of the flat lying formic acid chains was determined by low energy electron diffraction (LEED) as a (2r3 x r19) unit cell. Annealing results in a complete desorption at 190 K. Sequential adsorption of formic acid and water at 90 K shows no significant chemical interaction. Upon annealing the coadsorbed layer to 140 K a hydrogenbonded cyclic complex of formic acid with one water molecule could be identified using isotopically labelled adsorbates. Upon further annealing this complex decomposes leaving molecularly adsorbed formic acid on the surface at 160 K, accompanied by a proton exchange between formic acid and water. The influence of the alkane spacer chain length on the structure of biphenylalkanethiols on Au(111) surfaces was investigated as well. A systematic study was done on BPn-SAMs deposited from the gas phase. For every chain length a structure was found by LEED. Furthermore the influence of temperature on the structure was investigated in the range from room temperature up to about 400 K. To obviate influences from different preparation methods BP3 and BP4 was deposited from gas phase and from solution. No LEED spots were observed on BP4 SAMs deposited from solution. For BP3 an influence of the preparation could be excluded. For all BPn-SAMs a good agreement between LEED and STM data's was found. Nevertheless different unit cells were determined by LEED and STM consistent structures could be suggested considering the unit cell size given by LEED and the

  4. Surface alloying in Sn/Au(111) at elevated temperature

    Sadhukhan, Pampa; Singh, Vipin Kumar; Rai, Abhishek; Bhattacharya, Kuntala; Barman, Sudipta Roy

    2018-04-01

    On the basis of x-ray photoelectron spectroscopy, we show that when Sn is deposited on Au(111) single crystal surface at a substrate temperature TS=373 K, surface alloying occurs with the formation of AuSn phase. The evolution of the surface structure and the surface morphology has been studied by low energy electron diffraction and scanning tunneling microscopy, respectively as a function of Sn coverage and substrate temperatures.

  5. Overlayer structure of subphthalocyanine derivative deposited on Au (111) surface by a spray-jet technique

    Suzuki, Hitoshi; Yamada, Toshiki; Miki, Hideki; Mashiko, Shinro

    2006-01-01

    A new spray-jet technique was used to deposit subphthalocyanine derivative (chloro[tri-tert-butyl subphthalocyaninato]boron (TBSubPc)) on Au (111) surface in an ultra-high vacuum (UHV) chamber. The deposited molecular overlayer was observed with UHV scanning tunneling microscopy (STM) at 77 K. The STM images showed that TBSubPc molecules formed a stripe pattern with regular spacing, indicating that they preferentially adsorbed along the herringbone structure of the Au (111) surface. This behavior was very similar to that of TBSubPc molecules deposited by thermal evaporation

  6. Surface x-ray scattering and scanning tunneling microscopy studies at the Au(111) electrode

    Ocko, B.M.; Magnussen, O.M.; Wang, J.X.; Adzic, R.R.

    1993-01-01

    This chapter reviews Surface X-ray Scattering and Scanning Tunneling Microscopy results carried out at the Au(111) surface under electrochemical conditions. Results are presented for the reconstructed surface, and for bromide and thallium monolayers. These examples are used to illustrate the complementary nature of the techniques

  7. Investigation of Streptococcus mutans biofilm growth on modified Au(111)-surfaces using AFM and electrochemistry

    Hu, Yifan; Zhang, Jingdong; Ulstrup, Jens

    2011-01-01

    Biofilms of the bacterium Streptococcus mutans constitute perhaps the most important direct cause of human dental caries formation. We have studied S. mutans biofilm formation and properties on Au(111)-surfaces modified by self-assembled molecular monolayers (SAMs) of different thiol-based molecu...

  8. Electrochemistry of Hemin on Single-Crystal Au(111)-electrode Surfaces

    Zhang, Ling; Ulstrup, Jens; Zhang, Jingdong

    adsorption on well-defined single-crystal Au(111)-electrode surfaces using electrochemistry combined with scanning tunnelling microscopy under electrochemical control. Hemin gives two voltammetric peaks assigned to adsorbed monomers and dimmers (Fig. 1B). In situ STM shows that hemin self...

  9. Carbon monoxide oxidation on a Au(111 surface modified by spontaneously deposited Ru

    ROLF-JÜRGEN BEHM

    2001-04-01

    Full Text Available The spontaneous deposition of Ru on Au(111 was performed in 10-3 M RuCl3 + 0.5 M H2SO4 solution. The obtained surface was characterized by STM under potential control in 0.5 M H2SO4 solution. The coverage of the Au(111 terraces by deposited Ru was estimated by STM to be 0.02 ML. Step decoration could be noticed in the STM images, which indicates that the steps, as lined defects, are active sites for the nucleation of Ru monolayer islands, while the random distribution of Ru nuclei, observed on the terraces indicates point defects as active sites. The electrocatalytic activity of Au(111 surface modified by spontaneously deposited Ru was studied towards CO oxidation. The significant enhancement in the reaction rate compared to CO oxidation on a pure Au(111 surface, indicated that the edges of the deposited Ru islands were the active sites for the reaction.

  10. Voltammetry and Electrocatalysis of Achrornobacter Xylosoxidans Copper Nitrite Reductase on Functionalized Au(111)-Electrode Surfaces

    Welinder, Anna C.; Zhang, Jingdong; Hansen, Allan G.

    2007-01-01

    A long-standing issue in protein film voltammetry (PFV), particularly electrocatalytic voltammetry of redox enzyme monolayers, is the variability of protein adsorption modes, reflected in distributions of catalytic activity of the adsorbed protein/enzyme molecules. Use of well-defined, atomically...... planar electrode surfaces is a step towards the resolution of this central issue. We report here the voltammetry of copper nitrite reductase (CNiR, Achromobacter xylosoxidons) on Au(111)-electrode surfaces modified by monolayers of a broad variety of thiol-based linker molecules. These represent......NiR thus shows highly efficient, close to ideal reversible electrocatalytic voltammetry on cysteamine-covered Au(111)-electrode surfaces, most likely due to two cysteamine orientations previously disclosed by in situ scanning tunnelling microscopy. Such a dual orientation exposes both a hydrophobic...

  11. Mapping the Diffusion Potential of a Reconstructed Au(111) Surface at Nanometer Scale with 2D Molecular Gas

    Yan Shi-Chao; Xie Nan; Gong Hui-Qi; Guo Yang; Shan Xin-Yan; Lu Xing-Hua; Sun Qian

    2012-01-01

    The adsorption and diffusion behaviors of benzene molecules on an Au(111) surface are investigated by low-temperature scanning tunneling microscopy. A herringbone surface reconstruction of the Au(111) surface is imaged with atomic resolution, and significantly different behaviors are observed for benzene molecules adsorbed on step edges and terraces. The electric field induced modification in the molecular diffusion potential is revealed with a 2D molecular gas model, and a new method is developed to map the diffusion potential over the reconstructed Au(111) surface at the nanometer scale. (condensed matter: structure, mechanical and thermal properties)

  12. Hydrogen adsorption on bimetallic PdAu(111) surface alloys

    Takehiro, Naoki; Liu, Ping; Bergbreiter, Andreas

    2014-01-01

    The adsorption of hydrogen on structurally well defined PdAu-Pd(111) monolayer surface alloys was investigated in a combined experimental and theoretical study, aiming at a quantitative understanding of the adsorption and desorption properties of individual PdAu nanostructures. Combining...... the structural information obtained by high resolution scanning tunneling microscopy (STM), in particular on the abundance of specific adsorption ensembles at different Pd surface concentrations, with information on the adsorption properties derived from temperature programmed desorption (TPD) spectroscopy...... and high resolution electron energy loss spectroscopy (HREELS) provides conclusions on the minimum ensemble size for dissociative adsorption of hydrogen and on the adsorption energies on different sites active for adsorption. Density functional theory (DFT) based calculations give detailed insight...

  13. Self-assembly of phosphorylated dihydroceramide at Au(111) electrode surface

    Pawłowski, Jan; Juhaniewicz, Joanna; Sęk, Sławomir, E-mail: slasek@chem.uw.edu.pl

    2017-01-15

    Although the adsorption of lipids on reconstructed Au(111) surface and formation of highly ordered stripe-like domains are well-known phenomena, the exact orientation of the molecules with respect to the substrate remains unclear. Therefore, in this study we have focused on the structure and arrangement of lipid molecules forming highly ordered stripe-like domains at gold electrode-electrolyte interface. N-palmitoyl-D-erythro-dihydroceramide-1-phosphate was selected as model compound since its ability to transform into hemimicellar structure is limited. This way it was possible to get very stable lipid film with characteristic stripe-like pattern. Application of complementary techniques such as atomic force microscopy and scanning tunneling microscopy enabled detailed characteristics of lipid adlayer adsorbed on Au(111) electrode. Based on careful analysis of the experimental results, we have proposed a model which describes the arrangement of the molecules within the film. In general, it assumes flat-lying orientation of the lipids but only one hydrocarbon chain of phosphorylated dihydroceramide is involved in direct interaction with gold. - Highlights: • STM and AFM methods were used to examine adsorption of model lipid on Au(111). • Self-assembly of model lipid leads to formation of highly organized molecular film. • The model is proposed which reproduces the STM contrast.

  14. Evolution of magnetism of Cr nanoclusters on a Au(111) surface

    Gotsis, Harry; Kioussis, Nicholas; Papaconstantopoulos, Dimitri

    2004-03-01

    Advances in low-temperature scanning tunneling microscopy under ultrahigh vacuum have provided new opportunities for investigating the magnetic structures of nanoclusters adsorbed on surfaces. Recent STM studies of Cr trimers on the Au(111) surface suggest a switching between two distinct electronic states. We have carried out ab initio electronic structure calculations to investigate the structural, electronic and magnetic properties of isolated Cr atoms, Cr dimers and trimers in different geometry. We will present results for the evolution of magnetic behavior including noncollinear magnetism and provide insight in the connection between magnetism and geometry.

  15. Vanadium and molybdenum oxide thin films on Au(111). Growth and surface characterization

    Guimond, Sebastien

    2009-06-04

    The growth and the surface structure of well-ordered V{sub 2}O{sub 3}, V{sub 2}O{sub 5} and MoO{sub 3} thin films have been investigated in this work. These films are seen as model systems for the study of elementary reaction steps occurring on vanadia and molybdena-based selective oxidation catalysts. It is shown that well-ordered V{sub 2}O{sub 3}(0001) thin films can be prepared on Au(111). The films are terminated by vanadyl groups which are not part of the V{sub 2}O{sub 3} bulk structure. Electron irradiation specifically removes the oxygen atoms of the vanadyl groups, resulting in a V-terminated surface. The fraction of removed vanadyl groups is controlled by the electron dose. Such surfaces constitute interesting models to probe the relative role of both the vanadyl groups and the undercoordinated V ions at the surface of vanadia catalysts. The growth of well-ordered V{sub 2}O{sub 5}(001) and MoO{sub 3}(010) thin films containing few point defects is reported here for the first time. These films were grown on Au(111) by oxidation under 50 mbar O{sub 2} in a dedicated high pressure cell. Contrary to some of the results found in the literature, the films are not easily reduced by annealing in UHV. This evidences the contribution of radiation and surface contamination in some of the reported thermal reduction experiments. The growth of ultrathin V{sub 2}O{sub 5} and MoO{sub 3} layers on Au(111) results in formation of interface-specific monolayer structures. These layers are coincidence lattices and they do not correspond to any known oxide bulk structure. They are assumed to be stabilized by electronic interaction with Au(111). Their formation illustrates the polymorphic character and the ease of coordination units rearrangement which are characteristic of both oxides. The formation of a second layer apparently precedes the growth of bulk-like crystallites for both oxides. This observation is at odds with a common assumption that crystals nucleate as soon as a

  16. Vanadium and molybdenum oxide thin films on Au(111). Growth and surface characterization

    Guimond, Sebastien

    2009-01-01

    The growth and the surface structure of well-ordered V 2 O 3 , V 2 O 5 and MoO 3 thin films have been investigated in this work. These films are seen as model systems for the study of elementary reaction steps occurring on vanadia and molybdena-based selective oxidation catalysts. It is shown that well-ordered V 2 O 3 (0001) thin films can be prepared on Au(111). The films are terminated by vanadyl groups which are not part of the V 2 O 3 bulk structure. Electron irradiation specifically removes the oxygen atoms of the vanadyl groups, resulting in a V-terminated surface. The fraction of removed vanadyl groups is controlled by the electron dose. Such surfaces constitute interesting models to probe the relative role of both the vanadyl groups and the undercoordinated V ions at the surface of vanadia catalysts. The growth of well-ordered V 2 O 5 (001) and MoO 3 (010) thin films containing few point defects is reported here for the first time. These films were grown on Au(111) by oxidation under 50 mbar O 2 in a dedicated high pressure cell. Contrary to some of the results found in the literature, the films are not easily reduced by annealing in UHV. This evidences the contribution of radiation and surface contamination in some of the reported thermal reduction experiments. The growth of ultrathin V 2 O 5 and MoO 3 layers on Au(111) results in formation of interface-specific monolayer structures. These layers are coincidence lattices and they do not correspond to any known oxide bulk structure. They are assumed to be stabilized by electronic interaction with Au(111). Their formation illustrates the polymorphic character and the ease of coordination units rearrangement which are characteristic of both oxides. The formation of a second layer apparently precedes the growth of bulk-like crystallites for both oxides. This observation is at odds with a common assumption that crystals nucleate as soon as a monolayer is formed dur-ing the preparation of supported vanadia

  17. Manipulation and control of a single molecular rotor on Au (111) surface

    Hai-Gang, Zhang; Jin-Hai, Mao; Qi, Liu; Nan, Jiang; Hai-Tao, Zhou; Hai-Ming, Guo; Dong-Xia, Shi; Hong-Jun, Gao

    2010-01-01

    Three different methods are used to manipulate and control phthalocyanine based single molecular rotors on Au (111) surface: (1) changing the molecular structure to alter the rotation potential; (2) using the tunnelling current of the scanning tunnelling microscope (STM) to change the thermal equilibrium of the molecular rotor; (3) artificial manipulation of the molecular rotor to switch the rotation on or off by an STM tip. Furthermore, a molecular 'gear wheel' is successfully achieved with two neighbouring molecules. (cross-disciplinary physics and related areas of science and technology)

  18. Potential-induced structural transitions of DL-homocysteine monolayers on Au(111) electrode surfaces

    Zhang, Jingdong; Demetriou, Anna; Welinder, Anne Christina

    2005-01-01

    Monolayers of homocysteine on Au(111)-surfaces have been investigated by voltammetry, in situ scanning tunnelling microscopy (STM) and subtractively normalised interfacial Fourier transform spectroscopy (SNIFTIRS). A pair of sharp voltammetric peaks build up in the potential range 0 to -0.1 V (vs...... potentials at pH 7.7. The molecules pack into highly ordered domains around the peak potential. High-resolution in situ STM reveals a (root 3 x 5) R30 degrees lattice with three homocysteine molecules in each unit cell. The adlayer changes into disordered structures on either side of the peak potential...

  19. Electron induced conformational changes of an imine-based molecular switch on a Au(111) surface

    Lotze, Christian; Henningsen, Nils; Franke, Katharina; Schulze, Gunnar; Pascual, Jose Ignacio [Inst. f. Experimentalphysik, Freie Universitaet Berlin (Germany); Luo, Ying; Haag, Rainer [Inst. f. Organische Chemie, Freie Universitaet Berlin (Germany)

    2009-07-01

    Azobenzene-based molecules exhibit a cis-trans configurational photoisomerisation in solution. Recently, the adsorption properties of azobenzene derivatives have been investigated on different metal surfaces in order to explore the possible changes in the film properties induced by external stimuli. In azobenzene, the diazo-bridge is a key group for the isomerization process. Its interaction with a metal surface is dominated through the N lone-pair electrons, which reduces the efficiency of the conformational change. In order to reduce the molecule-surface interaction, we explore an alternative molecular architecture by substituting the diazo-bridge (-N=N-) of azobenzene by an imine-group (-N=CH-). We have investigated the imine-based compound para-carboxyl-di-benzene-imine (PCI) adsorbed on a Au(111) surface. The carboxylic terminations mediates the formation of strongly bonded molecular dimers, which align in ordered rows preferentially following the fcc regions of the Au(111) herringbone reconstruction. Low temperature scanning tunneling microscopy was used to induce conformational changes between trans and cis state of individual molecules in a molecular monolayer.

  20. Surface Structures and Thermal Desorption Behaviors of Cyclopentanethiol Self-Assembled Monolayers on Au(111)

    Kang, Hun Gu; Kim, You Young; Park, Tae Sun; Noh, Jae Geun [Hanyang University, Seoul (Korea, Republic of); Park, Joon B. [Chonbuk National University, Jeonju (Korea, Republic of); Ito, Eisuke; Hara, Masahiko [RIKEN-HYU Collaboration Center, Saitama (Japan)

    2011-04-15

    The surface structures, adsorption conditions, and thermal desorption behaviors of cyclopentanethiol (CPT) self-assembled monolayers (SAMs) on Au(111) were investigated by scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and thermal desorption spectroscopy (TDS). STM imaging revealed that although the adsorption of CPT on Au(111) at room temperature generates disordered SAMs, CPT molecules at 50 .deg. C formed well-ordered SAMs with a (2√3 x √5)R41{sup .}deg. packing structure. XPS measurements showed that CPT SAMs at room temperature were formed via chemical reactions between the sulfur atoms and gold surfaces. TDS measurements showed two dominant TD peaks for the decomposed fragments (C{sub 5}H{sub 9} {sup +}, m/e = 69) generated via C-S bond cleavage and the parent molecular species (C{sub 5}H{sub 9}SH{sup +}, m/e = 102) derived from a recombination of the chemisorbed thiolates and hydrogen atoms near 440 K. Interestingly, dimerization of sulfur atoms in n-alkanethiol SAMs usually occurs during thermal desorption and the same reaction did not happen for CPT SAMs, which may be due to the steric hindrance of cyclic rings of the CPT molecules. In this study, we demonstrated that the alicyclic ring of organic thiols strongly affected the surface structure and thermal desorption behavior of SAMs, thus providing a good method for controlling chemical and physical properties of organic thiol SAMs.

  1. Surface Structures and Thermal Desorption Behaviors of Cyclopentanethiol Self-Assembled Monolayers on Au(111)

    Kang, Hun Gu; Kim, You Young; Park, Tae Sun; Noh, Jae Geun; Park, Joon B.; Ito, Eisuke; Hara, Masahiko

    2011-01-01

    The surface structures, adsorption conditions, and thermal desorption behaviors of cyclopentanethiol (CPT) self-assembled monolayers (SAMs) on Au(111) were investigated by scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and thermal desorption spectroscopy (TDS). STM imaging revealed that although the adsorption of CPT on Au(111) at room temperature generates disordered SAMs, CPT molecules at 50 .deg. C formed well-ordered SAMs with a (2√3 x √5)R41".deg. packing structure. XPS measurements showed that CPT SAMs at room temperature were formed via chemical reactions between the sulfur atoms and gold surfaces. TDS measurements showed two dominant TD peaks for the decomposed fragments (C_5H_9 "+, m/e = 69) generated via C-S bond cleavage and the parent molecular species (C_5H_9SH"+, m/e = 102) derived from a recombination of the chemisorbed thiolates and hydrogen atoms near 440 K. Interestingly, dimerization of sulfur atoms in n-alkanethiol SAMs usually occurs during thermal desorption and the same reaction did not happen for CPT SAMs, which may be due to the steric hindrance of cyclic rings of the CPT molecules. In this study, we demonstrated that the alicyclic ring of organic thiols strongly affected the surface structure and thermal desorption behavior of SAMs, thus providing a good method for controlling chemical and physical properties of organic thiol SAMs

  2. Effects of chlorine and oxygen coverage on the structure of the Au(111) surface

    Baker, Thomas A.; Friend, Cynthia M.; Kaxiras, Efthimios

    2009-01-01

    We investigate the effects of Cl and O coverage on the atomic structure of the Au(111) surface using density functional theory calculations. We find that the release and incorporation of gold atoms in the adsorbate layer becomes energetically favorable only at high coverages of either O or Cl (>0.66 ML (monolayer) for O and >0.33 ML for Cl), whereas adsorption without the incorporation of gold is favorable at lower coverages. The bonding between the adsorbate and gold substrate changes significantly with coverage, becoming more covalent (less ionic) at higher Cl and O coverage. This is based on the fact that at higher coverages there is less ionic charge transfer to the adsorbate, while the electron density in the region between the adsorbate and a surface gold atom is increased. Our results illustrate that the O and Cl coverage on Au(111) can dramatically affect its structure and bonding, which are important features in any application of gold involving these adsorbates.

  3. Tin-phthalocyanine adsorption and diffusion on Cu and Au (111) surfaces: A density functional theory study

    Qin, Dan; Ge, Xu-Jin; Lü, Jing-Tao

    2018-05-01

    Through density functional theory based calculations, we study the adsorption and diffusion of tin phthalocyanine (SnPc) molecule on Au(111) and Cu(111) surfaces. SnPc has two conformers with Sn pointing to the vacuum (Sn-up) and substrate (Sn-down), respectively. The binding energies of the two conformers with different adsorption sites on the two surfaces, including top, bridge, fcc, hcp, are calculated and compared. It is found that the SnPc molecule binds stronger on Cu(111) surface, with binding energy about 1 eV larger than that on Au(111). Only the bridge and top adsorption sites are stable on Cu(111), while all the four adsorption sites are stable on Au(111), with small diffusion barriers between them. Moreover, the flipping barrier from Sn-up to Sn-down conformer is of the same magnitude on the two metal surfaces. These results are consistent with a recent experiment [Zhang, et al., Angew. Chem., 56, 11769 (2017)], which shows that conformation change from Sn-up to Sn-down on Cu(111) surface can be induced by a C60-functionalized STM tip, while similar change is difficult to realize on Au(111), due to smaller diffusion barrier on Au(111).

  4. Self-organization of a self-assembled supramolecular rectangle, square, and three-dimensional cage on Au111 surfaces.

    Yuan, Qun-Hui; Wan, Li-Jun; Jude, Hershel; Stang, Peter J

    2005-11-23

    The structure and conformation of three self-assembled supramolecular species, a rectangle, a square, and a three-dimensional cage, on Au111 surfaces were investigated by scanning tunneling microscopy. These supramolecular assemblies adsorb on Au111 surfaces and self-organize to form highly ordered adlayers with distinct conformations that are consistent with their chemical structures. The faces of the supramolecular rectangle and square lie flat on the surface, preserving their rectangle and square conformations, respectively. The three-dimensional cage also forms well-ordered adlayers on the gold surface, forming regular molecular rows of assemblies. When the rectangle and cage were mixed together, the assemblies separated into individual domains, and no mixed adlayers were observed. These results provide direct evidence of the noncrystalline solid-state structures of these assemblies and information about how they self-organize on Au111 surfaces, which is of importance in the potential manufacturing of functional nanostructures and devices.

  5. Mesoscopic self-organization of a self-assembled supramolecular rectangle on highly oriented pyrolytic graphite and Au(111) surfaces.

    Gong, Jian-Ru; Wan, Li-Jun; Yuan, Qun-Hui; Bai, Chun-Li; Jude, Hershel; Stang, Peter J

    2005-01-25

    A self-assembled supramolecular metallacyclic rectangle was investigated with scanning tunneling microscopy on highly oriented pyrolytic graphite and Au(111) surfaces. The rectangles spontaneously adsorb on both surfaces and self-organize into well ordered adlayers. On highly oriented pyrolytic graphite, the long edge of the rectangle stands on the surface, forming a 2D molecular network. In contrast, the face of the rectangle lays flat on the Au(111) surface, forming linear chains. The structures and intramolecular features obtained through high-resolution scanning tunneling microscopy imaging are discussed.

  6. Adsorption and switching properties of a N-benzylideneaniline based molecular switch on a Au(111) surface

    Ovari, Laszlo; Luo, Ying; Haag, Rainer; Leyssner, Felix; Tegeder, Petra; Wolf, Martin

    2010-01-01

    High resolution electron energy loss spectroscopy has been employed to analyze the adsorption geometry and the photoisomerization ability of the molecular switch carboxy-benzylideneaniline (CBA) adsorbed on Au(111). CBA on Au(111) adopts a planar (trans) configuration in the first monolayer (ML) as well as for higher coverages (up to 6 ML), in contrast to the strongly nonplanar geometry of the molecule in solution. Illumination with UV light of CBA in direct contact with the Au(111) surface (≤1 ML) caused no changes in the vibrational structure, whereas at higher coverages (>1 ML) pronounced modifications of vibrational features were observed, which we assign to a trans→cis isomerization. Thermal activation induced the back reaction to trans-CBA. We propose that the photoisomerization is driven by a direct (intramolecular) electronic excitation of the adsorbed CBA molecules in the second ML (and above) analogous to CBA in the liquid phase.

  7. Formation of Surface and Quantum-Well States in Ultra Thin Pt Films on the Au(111 Surface

    Igor V. Silkin

    2017-12-01

    Full Text Available The electronic structure of the Pt/Au(111 heterostructures with a number of Pt monolayers n ranging from one to three is studied in the density-functional-theory framework. The calculations demonstrate that the deposition of the Pt atomic thin films on gold substrate results in strong modifications of the electronic structure at the surface. In particular, the Au(111 s-p-type Shockley surface state becomes completely unoccupied at deposition of any number of Pt monolayers. The Pt adlayer generates numerous quantum-well states in various energy gaps of Au(111 with strong spatial confinement at the surface. As a result, strong enhancement in the local density of state at the surface Pt atomic layer in comparison with clean Pt surface is obtained. The excess in the density of states has maximal magnitude in the case of one monolayer Pt adlayer and gradually reduces with increasing number of Pt atomic layers. The spin–orbit coupling produces strong modification of the energy dispersion of the electronic states generated by the Pt adlayer and gives rise to certain quantum states with a characteristic Dirac-cone shape.

  8. Surface characterization of sulfur and alkanethiol self-assembled monolayers on Au(111)

    Vericat, C; Vela, M E; Benitez, G A; Gago, J A Martin; Torrelles, X; Salvarezza, R C

    2006-01-01

    In the last two decades surface science techniques have decisively contributed to our present knowledge of alkanethiol self-assembled monolayers (SAMs) on solid surfaces. These organic layers have been a challenge for surface scientists, in particular because of the soft nature of the organic material (which can be easily damaged by irradiation), the large number of atoms present in the molecules, and the complex physical chemistry involved in the self-assembly process. This challenge has been motivated by the appealing technological applications of SAMs that cover many fields of the emerging area of nanotechnology. Sulfur (S) is closely related to alkanethiols and can be used to understand basic aspects of the surface structure of SAMs. In this review we focus on the atomic/molecular structures of S-containing SAMs on Au(111). Particular emphasis is given to the substrate, adsorption sites, chemical state of the S-metal bond and also to the experimental and theoretical tools used to study these structures at the atomic or molecular levels. (topical review)

  9. Surface characterization of sulfur and alkanethiol self-assembled monolayers on Au(111)

    Vericat, C [Instituto de Investigaciones FisicoquImicas Teoricas y Aplicadas (INIFTA), Universidad Nacional de La Plata-CONICET, Sucursal 4 Casilla de Correo 16 (1900) La Plata (Argentina); Vela, M E [Instituto de Investigaciones FisicoquImicas Teoricas y Aplicadas (INIFTA), Universidad Nacional de La Plata-CONICET, Sucursal 4 Casilla de Correo 16 (1900) La Plata (Argentina); Benitez, G A [Instituto de Investigaciones FisicoquImicas Teoricas y Aplicadas (INIFTA), Universidad Nacional de La Plata-CONICET, Sucursal 4 Casilla de Correo 16 (1900) La Plata (Argentina); Gago, J A Martin [Centro de AstrobiologIa (CSIC-INTA), 28850 Torrejon de Ardoz Madrid (Spain); Torrelles, X [Instituto de Ciencia de Materiales de Barcelona (ICMAB), Barcelona (Spain); Salvarezza, R C [Instituto de Investigaciones FisicoquImicas Teoricas y Aplicadas (INIFTA), Universidad Nacional de La Plata-CONICET, Sucursal 4 Casilla de Correo 16 (1900) La Plata (Argentina)

    2006-12-06

    In the last two decades surface science techniques have decisively contributed to our present knowledge of alkanethiol self-assembled monolayers (SAMs) on solid surfaces. These organic layers have been a challenge for surface scientists, in particular because of the soft nature of the organic material (which can be easily damaged by irradiation), the large number of atoms present in the molecules, and the complex physical chemistry involved in the self-assembly process. This challenge has been motivated by the appealing technological applications of SAMs that cover many fields of the emerging area of nanotechnology. Sulfur (S) is closely related to alkanethiols and can be used to understand basic aspects of the surface structure of SAMs. In this review we focus on the atomic/molecular structures of S-containing SAMs on Au(111). Particular emphasis is given to the substrate, adsorption sites, chemical state of the S-metal bond and also to the experimental and theoretical tools used to study these structures at the atomic or molecular levels. (topical review)

  10. Infrared spectroscopy of molecular submonolayers on surfaces by infrared scanning tunneling microscopy: tetramantane on Au111.

    Pechenezhskiy, Ivan V; Hong, Xiaoping; Nguyen, Giang D; Dahl, Jeremy E P; Carlson, Robert M K; Wang, Feng; Crommie, Michael F

    2013-09-20

    We have developed a new scanning-tunneling-microscopy-based spectroscopy technique to characterize infrared (IR) absorption of submonolayers of molecules on conducting crystals. The technique employs a scanning tunneling microscope as a precise detector to measure the expansion of a molecule-decorated crystal that is irradiated by IR light from a tunable laser source. Using this technique, we obtain the IR absorption spectra of [121]tetramantane and [123]tetramantane on Au(111). Significant differences between the IR spectra for these two isomers show the power of this new technique to differentiate chemical structures even when single-molecule-resolved scanning tunneling microscopy (STM) images look quite similar. Furthermore, the new technique was found to yield significantly better spectral resolution than STM-based inelastic electron tunneling spectroscopy, and to allow determination of optical absorption cross sections. Compared to IR spectroscopy of bulk tetramantane powders, infrared scanning tunneling microscopy (IRSTM) spectra reveal narrower and blueshifted vibrational peaks for an ordered tetramantane adlayer. Differences between bulk and surface tetramantane vibrational spectra are explained via molecule-molecule interactions.

  11. Well-ordered structure of methylene blue monolayers on Au(111) surface: electrochemical scanning tunneling microscopy studies.

    Song, Yonghai; Wang, Li

    2009-02-01

    Well-ordered structure of methylene blue (MB) monolayers on Au(111) surface has been successfully obtained by controlling the substrate potential. Electrochemical scanning tunneling microscopy (ECSTM) examined the monolayers of MB on Au(111) in 0.1 M HClO(4) and showed long-range ordered, interweaved arrays of MB with quadratic symmetry on the substrate in the potential range of double-layer charging. High-resolution ECSTM image further revealed the details of the MB monolayers structure of c(5 x 5 radical 3)rect and the flat-lying orientation of ad-molecules. The dependence of molecular organization on the substrate potential and the formation mechanism of well-ordered structure on Au(111) surface were investigated in detail. The obtained well-ordered structure at the interface between a metal and an aqueous electrolyte might possibly be used as high-density device for signal memory and templates for the advanced nanopatterning of surfaces. (c) 2008 Wiley-Liss, Inc.

  12. In situ STM imaging and direct electrochemistry of Pyrococcus furiosus ferredoxin assembled on thiolate-modified Au(111) surfaces

    Zhang, Jingdong; Christensen, Hans Erik Mølager; Ooi, Bee Lean

    2004-01-01

    We have addressed here electron transfer (ET) of Pyrococcus furiosus ferredoxin (PfFd, 7.5 kDa) in both homogeneous solution using edge plane graphite (EPG) electrodes and in the adsorbed state by electrochemistry on surface-modified single-crystal Au(111) electrodes, This has been supported...... by surface microscopic structures of PfFd monolayers, as revealed by scanning tunneling microscopy under potential control (in situ STM). Direct ET between PfFd in phosphate buffer solution, pH 7.9, and EPG electrodes is observed in the presence of promoters. Neomycin gives rise to a pair of redox peaks...... with a formal potential of ca -430 mV (vs SCE), corresponding to [3Fe-4S](1+/0). The presence of an additional promoter, which can be propionic acid, alanine, or cysteine, induces a second pair of redox peaks at similar to-900 mV (vs SCE) arising from [3Fe-4S](0/1-). A robust neomycin-PfFd complex was detected...

  13. Electronic and magnetic properties of Mn{sub 12} single-molecule magnets on the Au(111) surface

    Voss, Soenke; Burgert, Michael; Fonin, Mikhail; Groth, Ulrich; Ruediger, Ulrich [Universitaet Konstanz (Germany); Michaelis, Christian; Brihuega, Ivan; Kern, Klaus [Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany); Dedkov, Yury S. [Institut fuer Festkoerperphysik, Technische Universitaet Dresden (Germany)

    2008-07-01

    The paramount interest in single-molecule magnets (SMMs) like Mn{sub 12}-acetate and its derivatives was inspired by numerous experimental and theoretical insights indicating the feasibility of addressing quantum effects of magnetism on a molecular scale. Due to its relatively high blocking temperature ({proportional_to}3 K) combined with the ability to identify well-defined spin states, Mn{sub 12} still remains the most favoured SMM possibly allowing the detection of magnetic fingerprints in transport properties of a single molecule. In this work, the electronic properties of Mn{sub 12} molecules chemically grafted on Au(111) surfaces have been studied by means of low temperature as well as room temperature scanning tunneling microscopy and spectroscopy (STS), X-ray absorption spectroscopy and photoelectron spectroscopy. The results revealed signatures from most probably intact Mn{sub 12} molecules while STS measurements in magnetic fields indicate the possibility to identify magnetic fingerprints in scanning tunneling spectra. The results will be discussed with respect to previous attempts to perform transport measurements on Mn{sub 12} SMMs.

  14. Potential-induced structural transitions of DL-homocysteine monolayers on Au(111) electrode surfaces

    Zhang Jingdong; Demetriou, Anna; Welinder, Anne Christina; Albrecht, Tim; Nichols, Richard J.; Ulstrup, Jens

    2005-01-01

    Monolayers of homocysteine on Au(111)-surfaces have been investigated by voltammetry, in situ scanning tunnelling microscopy (STM) and subtractively normalised interfacial Fourier transform spectroscopy (SNIFTIRS). A pair of sharp voltammetric peaks build up in the potential range 0 to -0.1V (vs. SCE) in phosphate buffer pH 7.7. The peak half-widths are about 25mV at a scan rate of 10mVs -1 . This is much smaller than for a one-electron Faradaic process (90.6mV) under similar conditions. The coverage of homocysteine is 6.1 (+/-0.2)x10 -10 molcm -2 , or 5.9x10 -5 Ccm -2 , from Au-S reductive desorption at -0.8V (SCE) in 0.1M NaOH, while the charge is only about 8x10 -6 Ccm -2 (pH 7.7) for the 0 to -0.1V peak. This suggests a capacitive origin. The peak potential and shape depend on pH. At pH 7.7 both cathodic and anodic peak currents reach a maximum, but drop at both higher and lower pH. The midpoint potential shows biphasic behaviour, decreasing linearly with increasing pH until pH 10.4 towards a constant value at higher pH. The cathodic and anodic peak charges decay at pH both higher and lower than 7.7. The homocysteine monolayer was investigated by in situ STM at different potentials at pH 7.7. The molecules pack into highly ordered domains around the peak potential. High-resolution in situ STM reveals a (√3x5) R30 deg. lattice with three homocysteine molecules in each unit cell. The adlayer changes into disordered structures on either side of the peak potential. This process is reversible. We propose that the voltammetric peaks are capacitive. The ordered domains are formed only around the potential of zero charge (pzc) and dissipate at potentials on either side of the peak, inducing mirror charge flow in the metallic electrode as the charged -COO - and -NH 3 + groups approach the surface. No bands for carboxylate coordinated to the surface were observed in SNIFTIRS implying more subtle orientation changes of the charged groups on transcending the voltammetric

  15. Monolayers of a De Novo Designed 4-Alpha-Helix Bundle Carboprotein and Partial Structures on Au(111)-Surfaces

    Brask, Jesper; Wackerbarth, Hainer; Jensen, Knud Jørgen

    2002-01-01

    on a galactopyranoside derivative with a thiol anchor aglycon suitable for surface immobilization on gold. The galactopyranoside with thiol anchor and the thiol anchor alone were prepared for comparison. Voltammetry of the three molecules on Au(111) showed reductive desorption peaks caused by monolayer adsorption via...... thiolate-Au bonding. In situ STM of the thiol anchor disclosed an ordered adlayer with clear domains and molecular features. This holds promise, broadly for single-molecule voltammetry and the SPM and scanning tunnelling microscopy (STM) of natural and synthetic proteins....

  16. Spin-polarized scanning tunneling spectroscopy of self-organized nanoscale Co islands on Au(111) surfaces.

    Schouteden, K; Muzychenko, D A; Van Haesendonck, C

    2008-07-01

    Magnetic monolayer and bilayer Co islands of only a few nanometer in size were grown by atomic deposition on atomically flat Au(111) films. The islands were studied in situ by scanning tunneling microscopy (STM) and spectroscopy at low temperatures. Spin-resolved tunneling spectroscopy, using an STM tip with a magnetic coating, revealed that the Co islands exhibit a net magnetization perpendicular to the substrate surface due to the presence of spin-polarized d-states. A random distribution of islands with either upward or downward pointing magnetization was observed, without any specific correlation of magnetization orientation with island size or island height.

  17. A first principles study on the electronic origins of silver segregation at the Ag-Au (111) surface

    Hoppe, Sandra; Müller, Stefan

    2017-12-01

    The special electronic structure of gold gives rise to many interesting phenomena, such as its color. The surface segregation of the silver-gold system has been the subject of numerous experimental and theoretical studies, yielding conflicting results ranging from strong Ag surface enrichment to Au surface segregation. Via a combined approach of density functional theory (DFT) and statistical physics, we have analyzed the segregation at the Ag-Au (111) surface with different Ag bulk concentrations. Interestingly, we observe a moderate Au surface segregation, which is due to a charge transfer from the less electronegative Ag to Au. Canonical Monte Carlo simulations suggest that the calculated concentration profile with a Au-enriched surface layer remains stable up to higher temperatures. However, the presence of adsorbed oxygen reverses the segregation behavior and leads to strong Ag enrichment of the surface layer.

  18. Atomic structure of screw dislocations intersecting the Au(111) surface: A combined scanning tunneling microscopy and molecular dynamics study

    Engbæk, Jakob; Schiøtz, Jakob; Dahl-Madsen, Bjarke

    2006-01-01

    The atomic-scale structure of naturally occurring screw dislocations intersecting a Au(111) surface has been investigated both experimentally by scanning tunneling microscopy (STM) and theoretically using molecular dynamics (MD) simulations. The step profiles of 166 dislocations were measured using...... STM. Many of them exhibit noninteger step-height plateaus with different widths. Clear evidence was found for the existence of two different populations at the surface with distinct (narrowed or widened) partial-splitting widths. All findings are fully confirmed by the MD simulations. The MD...... simulations extend the STM-, i.e., surface-, investigation to the subsurface region. Due to this additional insight, we can explain the different partial-splitting widths as the result of the interaction between the partial dislocations and the surface....

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

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

    2015-11-14

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

  20. Voltammetry and In Situ Scanning Tunnelling Microscopy of De Novo Designed Heme Protein Monolayers on Au(111)-Electrode Surfaces

    Albrecht, Tim; Li, Wu; Haehnel, Wolfgang

    2006-01-01

    to the tunnelling current, apparently due to slow electron transfer kinetics. As a consequence, STM images of heme-containing and heme-free MOP-C did not reveal any notable differences in apparent height or physical extension. The apparent height of heme-containing MOP-C did not show any dependence on the substrate...... potential being varied around the redox potential of the protein. The mere presence of an accessible molecular energy level is not sufficient to result in detectable tunnelling current modulation. (c) 2006 Elsevier B.V. All rights reserved.......In the present work, we report the electrochemical characterization and in situ scanning tunnelling microscopy (STM) studies of monolayers of an artificial de novo designed heme protein MOP-C, covalently immobilized on modified Au(111) surfaces. The protein forms closely packed monolayers, which...

  1. In situ surface X-ray diffraction study of ultrathin epitaxial Co films on Au(111) in alkaline solution

    Reikowski, Finn; Maroun, Fouad; Di, Nan; Allongue, Philippe; Ruge, Martin; Stettner, Jochim; Magnussen, Olaf M.

    2016-01-01

    The oxidation behavior of ultrathin electrodeposited Co films on Au(111) in alkaline electrolyte was studied using in situ surface X-ray scattering techniques employing synchrotron radiation and complementary optical reflectivity and electrochemical measurements. The films are formed at pH 4 and consist of (001)-oriented hcp Co crystallites that are several nm high, a few ten nm in diameter, and remain largely unchanged after electrolyte exchange to pH 12 solution. In the pre-oxidation peak only minor changes were observed in the diffraction studies, excluding the formation of Co(OH)_2 layers. In the potential regime of Co hydroxide formation a rapid reduction of the amount of Co is observed, while the characteristic height of the islands decreases only slightly. On longer times scales, growth of 3D crystals of Co(OH)_2 occurs as well as irreversible Co dissolution into the electrolyte is found. On the basis of the structural observations oxidation of the Co film is proposed to proceed via fast formation of an ultrathin passivating layer, followed by nucleation and growth of 3D hydroxide crystals at the grain boundaries in the Co deposit.

  2. Theoretical study of PTCDA adsorbed on the coinage metal surfaces, Ag(111), Au(111) and Cu(111)

    Romaner, L; Nabok, D; Puschnig, P; Ambrosch-Draxl, C; Zojer, E

    2009-01-01

    A thorough understanding of the adsorption of molecules on metallic surfaces is a crucial prerequisite for the development and improvement of functionalized materials. A prominent representative within the class of π-conjugated molecules is 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) which, adsorbed on the Ag(111), Au(111) or Cu(111) surfaces, shows characteristic trends for work-function modification, alignment of molecular levels with the substrate Fermi energy and binding distances. We carried out density functional theory (DFT) calculations to investigate to what extent these trends can be rationalized on a theoretical basis. We used different density functionals (DF) including a fully non-local van der Waals (vdW) DF capable of describing dispersion interactions. We show that, rather independent of the DF, the calculations yield level alignments and work-function modifications consistent with ultra-violet photoelectron spectroscopy when the monolayer is placed onto the surfaces at the experimental distances (as determined from x-ray standing wave experiments). The lowest unoccupied molecular orbital is occupied on the Ag and Cu surfaces, whereas it remains unoccupied on the Au surface. Simultaneously, the work function increases for Ag but decreases for Cu and Au. Adsorption distances and energies, on the other hand, depend very sensitively on the choice of the DF. While calculations in the local density approximation bind the monolayer consistently with the experimental trends, the generalized gradient approximation in several flavors fails to reproduce realistic distances and energies. Calculations employing the vdW-DF reveal that substantial bonding contributions arise from dispersive interactions. They yield reasonable binding energies but larger binding distances than the experiments.

  3. Energy-resolved attosecond interferometric photoemission from Ag(111) and Au(111) surfaces

    Ambrosio, M. J.; Thumm, U.

    2018-04-01

    Photoelectron emission from solid surfaces induced by attosecond pulse trains into the electric field of delayed phase-coherent infrared (IR) pulses allows the surface-specific observation of energy-resolved electronic phase accumulations and photoemission delays. We quantum-mechanically modeled interferometric photoemission spectra from the (111) surfaces of Au and Ag, including background contributions from secondary electrons and direct emission by the IR pulse, and adjusted parameters of our model to energy-resolved photoelectron spectra recently measured at a synchrotron light source by Roth et al. [J. Electron Spectrosc. 224, 84 (2018), 10.1016/j.elspec.2017.05.008]. Our calculated spectra and photoelectron phase shifts are in fair agreement with the experimental data of Locher et al. [Optica 2, 405 (2015), 10.1364/OPTICA.2.000405]. Our model's not reproducing the measured energy-dependent oscillations of the Ag(111) photoemission phases may be interpreted as evidence for subtle band-structure effects on the final-state photoelectron-surface interaction not accounted for in our simulation.

  4. First principles study of pentacene on Au(111)

    Stokbro, Kurt; Smidstrup, Søren

    2013-01-01

    We investigate the atomic and electronic structure of a single layer of pentacene on the Au(111) surface using density functional theory. To find the candidate structures we strain match the pentacene crystal geometry with the Au(111) surface, in this way we find pentacene overlayer structures with a low strain. We show that the geometries obtained with this approach has lower energy than previous proposed surface geometries of pentacene on Au(111). We also show that the geometry and workfunc...

  5. Effect of dispersion on surface interactions of cobalt(II) octaethylporphyrin monolayer on Au(111) and HOPG(0001) substrates: a comparative first principles study.

    Chilukuri, Bhaskar; Mazur, Ursula; Hipps, K W

    2014-07-21

    A density functional theory study of a cobalt(II) octaethylporphyrin (CoOEP) monolayer on Au(111) and HOPG(0001) surfaces was performed under periodic boundary conditions. Calculations with and without dispersion corrections are performed and the effect of van der Waals forces on the interface properties is analyzed. Calculations have determined that the CoOEP molecule tends to bind at the 3-fold and the 6-fold center sites on Au(111) and HOPG(0001), respectively. Geometric optimizations at the center binding sites have indicated that the porphyrin molecules (in the monolayer) lie flat on both substrates. Calculations also reveal that the CoOEP monolayer binds slightly more strongly to Au(111) than to HOPG(0001). Charge density difference plots disclose that charge is redistributed mostly around the porphyrin plane and the first layer of the substrates. Dispersion interactions cause a larger substrate to molecule charge pushback on Au(111) than on HOPG. CoOEP adsorption tends to lower the work functions of either substrate, qualitatively agreeing with the experimental photoelectron spectroscopic data. Comparison of the density of states (DOS) of the isolated CoOEP molecule with that on gold and HOPG substrates showed significant band shifts around the Fermi energy due to intermolecular orbital hybridization. Simulated STM images were plotted with the Tersoff-Hamann approach using the local density of states, which also agree with the experimental results. This study elucidates the role of dispersion for better describing porphyrin-substrate interactions. A DFT based overview of geometric, adsorption and electronic properties of a porphyrin monolayer on conductive surfaces is presented.

  6. Electrochemistry and in situ scanning tunnelling microscopy of pure and redox-marked DNA- and UNA-based oligonucleotides on Au(111)-electrode surfaces

    Hansen, Allan Glargaard; Salvatore, Princia; Karlsen, K.

    2013-01-01

    the strongest and in accord with multiple site Ru-attachment. In situ STM disclosed molecular scale features in varying coverage on addition of the metal ions. The Ru-derivatives showed a bias voltage dependent broad maximum in the tunnelling current–overpotential correlation which could be correlated......We have studied adsorption and electrochemical electron transfer of several 13- and 15-base DNA and UNA (unlocked nucleic acids) oligonucleotides (ONs) linked to Au(111)-electrode surfaces via a 50-C6-SH group using cyclic voltammetry (CV) and scanning tunnelling microscopy in aqueous buffer under...

  7. Mechanical and charge transport properties of alkanethiol self-assembled monolayers on Au (111) surface: The Role of Molecular Tilt

    Mulleregan, Alice; Qi, Yabing; Ratera, Imma; Park, Jeong Y.; Ashby, Paul D.; Quek, Su Ying; Neaton, J. B.; Salmeron, Miquel

    2007-11-12

    The relationship between charge transport and mechanical properties of alkanethiol self-assembled monolayers (SAM) on Au(111) films has been investigated using an atomic force microscope with a conductive tip. Molecular tilts induced by the pressure applied by the tip cause stepwise increases in film conductivity. A decay constant {beta} = 0.57 {+-} 0.03 {angstrom}{sup -1} was found for the current passing through the film as a function of tip-substrate separation due to this molecular tilt. This is significantly smaller than the value of {approx} 1 {angstrom}{sup -1} found when the separation is changed by changing the length of the alkanethiol molecules. Calculations indicate that for isolated dithiol molecules S-bonded to hollow sites, the junction conductance does not vary significantly as a function of molecular tilt. The impact of S-Au bonding on SAM conductance is discussed.

  8. In-situ STM study of phosphate adsorption on Cu(111), Au(111) and Cu/Au(111) electrodes

    Schlaup, Christian; Horch, Sebastian

    2013-01-01

    The interaction of Cu(111), Au(111) and Cu-covered Au(111) electrodes with a neutral phosphate buffer solution has been studied by means of cyclic voltammetry (CV) and in situ electrochemical scanning tunneling microscopy (EC-STM). Under low potential conditions, both the Cu(111) and the Au(111......) surface appear apparently adsorbate free, indicated by the presence of a (4×4) structure and the herringbone surface reconstruction, respectively. Upon potential increase, phosphate anions adsorb on both surfaces and for Cu(111) the formation of a (√3×√3)R30° structure is found, whereas on Au(111) a "(√3......×√7)" structure is formed. For a Cu-submonolayer on Au(111), coadsorption of phosphate anions leads to the formation of a (2×2) vacancy structure within an assumed pseudomorphic structure of the Cu-submonolayer with the phosphate anions occupying the vacancies. When desorbing the phosphate anions at low...

  9. First principles-based adsorption comparison of group IV elements (C, Si, Ge, and Sn) on Au(111)/Ag(111) surface

    Chakraborty, Sudip; Rajesh, Ch.

    2012-01-01

    We have reported a first-principle investigation of the structural properties of monomer and dimer for group IV elements (C, Si, Ge, and Sn) adsorbed on the Au(111) and Ag(111) surfaces. The calculations were performed by means of a plane wave based pseudopotential method under the framework of density functional theory. The results reveal the preference of adatom to be adsorbed on the hexagonal closed packed site of the metal (111) surfaces with strong binding energy. The structures introduce interlayer forces in the adsorbate. The strong bonding with the surface atoms is a result of p–d hybridization. The adsorption energy follows a sequence as one goes down in the group IV elements which imply that the interaction of the group IV elements with Au/Ag is decreasing as the atomic number increases.

  10. Long-range interfacial electron transfer and electrocatalysis of molecular scale Prussian Blue nanoparticles linked to Au(111)-electrode surfaces by different chemical contacting groups

    Zhu, Nan; Ulstrup, Jens; Chi, Qijin

    2017-01-01

    We have explored interfacial electrochemical electron transfer (ET) and electrocatalysis of 5–6 nm Prussian Blue nanoparticles (PBNPs) immobilized on Au(111)-electrode surfaces via molecular wiring with variable-length, and differently functionalized thiol-based self-assembled molecular monolayers...... (SAMs). The SAMs contain positively (−NH3+) or negatively charged (–COO–) terminal group, as well an electrostatically neutral hydrophobic terminal group (–CH3). The surface microscopic structures of the immobilized PBNPs were characterized by high-resolution atomic force microscopy (AFM) directly...... in aqueous electrolyte solution under the same conditions as for electrochemical measurements. The PBNPs displayed fast and reversible interfacial ET on all the surfaces, notably in multi-ET steps as reflected in narrow voltammetric peaks. The ET kinetics can be controlled by adjusting the length of the SAM...

  11. Coexistence of multiple conformations in cysteamine monolayers on Au(111)

    Zhang, Jingdong; Bilic, A; Reimers, JR

    2005-01-01

    The structural organization, catalytic function, and electronic properties of cysteamine monolayers on Au(111) have been addressed comprehensively by voltammetry, in situ scanning tunneling microscopy (STM) in anaerobic environment, and a priori molecular dynamics (MD) simulation and STM image si...

  12. A periodic mixed gaussians-plane waves DFT study on simple thiols on Au(111): adsorbate species, surface reconstruction, and thiols functionalization.

    Rajaraman, Gopalan; Caneschi, Andrea; Gatteschi, Dante; Totti, Federico

    2011-03-07

    Here we present DFT calculations based on a periodic mixed gaussians/plane waves approach to study the energetics, structure, bonding of SAMs of simple thiols on Au(111). Several open issues such as structure, bonding and the nature of adsorbate are taken into account. We started with methyl thiols (MeSH) on Au(111) to establish the nature of the adsorbate. We have considered several structural models embracing the reconstructed surface scenario along with the MeS˙-Au(ad)-MeS˙ type motif put forward in recent years. Our calculations suggest a clear preference for the homolytic cleavage of the S-H bond leading to a stable MeS˙ on a gold surface. In agreement with the recent literature studies, the reconstructed models of the MeS˙ species are found to be energetically preferred over unreconstructed models. Besides, our calculations reveal that the model with 1:2 Au(ad)/thiols ratio, i.e. MeS˙-Au(ad)-MeS˙, is energetically preferred compared to the clean and 1:1 ratio models, in agreement with the experimental and theoretical evidences. We have also performed Molecular Orbital/Natural Bond Orbital, MO/NBO, analysis to understand the electronic structure and bonding in different structural motifs and many useful insights have been gained. Finally, the studies have then been extended to alkyl thiols of the RSR' (R, R' = Me, Et and Ph) type and here our calculations again reveal a preference for the RS˙ type species adsorption for clean as well as for reconstructed 1:2 Au(ad)/thiols ratio models.

  13. Physisorption of three amine terminated molecules (TMBDA, BDA, TFBDA) on the Au(111) Surface: The Role of van der Waals Interaction

    Aminpour, Maral; Le, Duy; Rahman, Talat S.

    2012-02-01

    Recently, the electronic properties and alignment of tetramethyl-1,4-benzenediamine (TMBDA), 1,4-benzenediamine (BDA) and tetrafluro-1,4-benzenediamine (TFBDA) molecules were studied experimentally. Discrepancies were found for both the binding energy and the molecule tilt angle with respect to the surface, when results were compared with density functional theory calculations [1]. We have included the effect of vdW interactions both between the molecules and the Au(111) surface and find binding energies which are in very good agreement with experiments. We also find that at low coverages each of these molecules would adsorb almost parallel to the surface. N-Au bond lengths and charge redistribution on adsorption of the molecules are also analyzed. Our calculations are based on DFT using vdW-DF exchange correlation functionals. For BDA (since we are aware of experimental data), we show that for higher coverage, inclusion of intermolecular van der Waals interaction leads to tilting of the molecules with respect to the surface and formation of line structures. Our results demonstrate the central role played by intermolecular interaction in pattern formation on this surface.[4pt] [1] M. Dell'Angela et al, Nano Lett. 2010, 10, 2470; M. Kamenetska et al, J. Phys. Chem. C, 2011, 115, 12625

  14. Self-assembled organic radicals on Au(111) surfaces: a combined ToF-SIMS, STM, and ESR study.

    Mannini, Matteo; Sorace, Lorenzo; Gorini, Lapo; Piras, Federica M; Caneschi, Andrea; Magnani, Agnese; Menichetti, Stefano; Gatteschi, Dante

    2007-02-27

    Electron spin resonance (ESR), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and scanning tunneling microscopy (STM) have been used in parallel to characterize the deposition on gold surface of a series of nitronyl nitroxide radicals. These compounds have been specifically synthesized with methyl-thio linking groups suitable to interact with the gold surface to form self-assembled monolayers (SAMs), which can be considered relevant in the research for molecular-based spintronics devices, as suggested in recent papers. The degree of the expected ordering on the surface of these SAMs has been tuned by varying the chemical structure of synthesized radicals. ToF-SIMS has been used to support the evidence of the occurrence of the deposition process. STM has shown the different qualities of the obtained SAMs, with the degree of local order increasing as the degree of freedom of the molecules on the surface is decreased. Finally, ESR has confirmed that the deposition process does not affect the paramagnetic characteristics of radicals and that it affords a complete single-layered coverage of the surface. Further, the absence of angular dependence in the spectra indicates that the small regions of local ordering do not give rise to a long-range order and suggests a quite large mobility of the radical on the surface, probably due to the weak interaction with gold provided by the methyl-thio linking group.

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

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

    2015-09-28

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

  16. Hydrogen evolution on Au(111) covered with submonolayers of Pd

    Björketun, Mårten; Karlberg, Gustav; Rossmeisl, Jan

    2011-01-01

    A theoretical investigation of electrochemical hydrogen evolution on Au(111) covered with submonolayers of Pd is presented. The size and shape of monoatomically high Pd islands formed on the Au(111) surface are determined using Monte Carlo simulations, for Pd coverages varying from 0.02 to 0.95 ML....... The energetics of adsorption and desorption of hydrogen on/from different types of sites on the Pd-Au(111) surface are assessed by means of density functional theory calculations combined with thermodynamic modeling. Based on the density functional and Monte Carlo data, the hydrogen evolution activity...... is evaluated with a micro-kinetic model. The analysis reproduces measured Pd-coverage-dependent activities for Pd submonolayers exceeding similar to 0.15 ML and enables the relative contributions from different types of electrocatalytically active sites to be determined. Finally, the implications of surface...

  17. Solvent effects on the adsorption and self-organization of Mn12 on Au(111).

    Pineider, Francesco; Mannini, Matteo; Sessoli, Roberta; Caneschi, Andrea; Barreca, Davide; Armelao, Lidia; Cornia, Andrea; Tondello, Eugenio; Gatteschi, Dante

    2007-11-06

    A sulfur-containing single molecule magnet, [Mn12O12(O2CC6H4SCH3)16(H2O)4], was assembled from solution on a Au(111) surface affording both submonolayer and monolayer coverages. The adsorbate morphology and the degree of coverage were inspected by scanning tunneling microscopy (STM), while X-ray photoelectron spectroscopy (XPS) allowed the determination of the chemical nature of the adsorbate on a qualitative and quantitative basis. The properties of the adsorbates were found to be strongly dependent on the solvent used to dissolve the magnetic complex. In particular, systems prepared from tetrahydrofuran solutions gave arrays of isolated and partially ordered clusters on the gold substrate, while samples prepared from dichloromethane exhibited a homogeneous monolayer coverage of the whole Au(111) surface. These findings are relevant to the optimization of magnetic addressing of single molecule magnets on surfaces.

  18. Substrate induced ordering of molecular adsorbates on Au(111)

    Schott, J.H.; White, H.S.; Arana, C.R.

    1992-01-01

    Using scanning tunneling microscopy in dimethylformate, [Ru(bpy) 2 (bpy-(CH 2 ) x -bpy) 2+ ] (x = 4 and 5) monolayers adsorbed on the unreconstructed and √3 x 22 reconstructed surfaces of Au(111) were imaged in this paper. The substrate had a highly ordered pattern on the reconstructed surface, but random spatial distribution on the unreconstructed surface. 17 refs., 3 figs

  19. Interfacial Electrochemical Electron Transfer Processes in Bacterial Biofilm Environments on Au(111)

    Hu, Yifan; Zhang, Jingdong; Ulstrup, Jens

    2010-01-01

    We have studied Streptococcus mutans (S. mutans) biolilm growth and growth inhibition on Au(111)-surfaces using atomic force microscopy (AFM) and interfacial electrochemistry of a number of redox probe molecules. AFM of the biofilm growth and growth inhibition on both mica and Au(111)-surfaces wa...

  20. In-situ quartz crystal microgravimetric studies of molecular adsorbates containing thiol and hydroquinone moieties bound to Au(111) surfaces in aqueous electrolytes

    Mo, Y.; Sukenik, C.; Sandifer, M. [Case Western Univ., Cleveland, OH (United States); Barriga, R.J.; Soriaga, M.P.; Scherson, D. [Texas A& M Univ., College Station, TX (United States)

    1995-12-01

    The microgravimetric properties of monolayers of 2, 5-dihydroxythiophenol, 2,5-dihydroxybenzyl mercaptan, and 2, 5-dihydroxy-4-methylbenzyl mercaptan adsorbed on Au(111) single crystal electrodes were examined by in situ quartz crystal microbalance techniques in aqueous perchloric acid electrolytes. The results obtained are consistent with the reversible loss of an average of about three waters per adsorbed molecule as the layers are oxidized and subsequently reduced. These observations provide evidence for discrete changes in the extent of bound water within the hydroquinone/quinone layer as the oxidation state of the monolayer is changed. 9 refs., 4 figs.

  1. Single-molecule conductivity of non-redox and redox molecules at pure and gold-mined Au(111)-electrode surfaces

    Zhang, Jingdong; Chi, Qijin; Ulstrup, Jens

    The structure, two-dimensional organization, and function of molecules immobilized on solid surfaces can be addressed in a degree of detail that has reached the level of the single-molecule. In this context redox molecules are “smart” molecules adding sophisticated electronic function. Redox meta...

  2. Molecular dynamics and energy landscape of decanethiolates in self-assembled monolayers on Au(111) by STM

    Sotthewes, Kai; Wu, Hairong; Kumar, Avijit; Vancso, Gyula J.; Schön, Peter Manfred; Zandvliet, Henricus J.W.

    2013-01-01

    The energetics and dynamics of the various phases of decanethiolate self-assembled monolayers on Au(111) surfaces were studied with scanning tunneling microscopy. We have observed five different phases of the decanethiolate monolayer on Au(111): four ordered phases (β, δ, χ*, and ) and one

  3. Coverage dependent molecular assembly of anthraquinone on Au(111)

    DeLoach, Andrew S.; Conrad, Brad R.; Einstein, T. L.; Dougherty, Daniel B.

    2017-11-01

    A scanning tunneling microscopy study of anthraquinone (AQ) on the Au(111) surface shows that the molecules self-assemble into several structures depending on the local surface coverage. At high coverages, a close-packed saturated monolayer is observed, while at low coverages, mobile surface molecules coexist with stable chiral hexamer clusters. At intermediate coverages, a disordered 2D porous network interlinking close-packed islands is observed in contrast to the giant honeycomb networks observed for the same molecule on Cu(111). This difference verifies the predicted extreme sensitivity [J. Wyrick et al., Nano Lett. 11, 2944 (2011)] of the pore network to small changes in the surface electronic structure. Quantitative analysis of the 2D pore network reveals that the areas of the vacancy islands are distributed log-normally. Log-normal distributions are typically associated with the product of random variables (multiplicative noise), and we propose that the distribution of pore sizes for AQ on Au(111) originates from random linear rate constants for molecules to either desorb from the surface or detach from the region of a nucleated pore.

  4. In situ STM imaging of the structures of pentacene molecules adsorbed on Au(111).

    Pong, Ifan; Yau, Shuehlin; Huang, Peng-Yi; Chen, Ming-Chou; Hu, Tarng-Shiang; Yang, Yawchia; Lee, Yuh-Lang

    2009-09-01

    In situ scanning tunneling microscope (STM) was used to examine the spatial structures of pentacene molecules adsorbed onto a Au(111) single-crystal electrode from a benzene dosing solution containing 16-400 microM pentacene. Molecular-resolution STM imaging conducted in 0.1 M HClO(4) revealed highly ordered pentacene structures of ( radical31 x radical31)R8.9 degrees , (3 x 10), ( radical31 x 10), and ( radical7 x 2 radical7)R19.1 degrees adsorbed on the reconstructed Au(111) electrode dosed with different pentacene solutions. These pentacene structures and the reconstructed Au(111) substrate were stable between 0.2 and 0.8 V [vs reversible hydrogen electrode, RHE]. Increasing the potential to E > 0.8 V lifted the reconstructed Au(111) surface and disrupted the ordered pentacene adlattices simultaneously. Ordered pentacene structures could be restored by applying potentials negative enough to reinforce the reconstructed Au(111). At potentials negative of 0.2 V, the adsorption of protons became increasingly important to displace adsorbed pentacene admolecules. Although the reconstructed Au(111) structure was not essential to produce ordered pentacene adlayers, it seemed to help the adsorption of pentacene molecules in a long-range ordered pattern. At room temperature (25 degrees C), approximately 100 pentacene molecules seen in STM images could rotate and align themselves to a neighboring domain in 10 s, suggesting that pentacene admolecules could be mobile on Au(111) under the STM imaging conditions of -150 mV in bias voltage and 1 nA in feedback current.

  5. The importance of accurate adiabatic interaction potentials for the correct description of electronically nonadiabatic vibrational energy transfer: A combined experimental and theoretical study of NO(v = 3) collisions with a Au(111) surface

    Golibrzuch, Kai; Shirhatti, Pranav R.; Kandratsenka, Alexander; Wodtke, Alec M.; Bartels, Christof [Institute for Physical Chemistry, Georg August University of Göttingen, Göttingen 37077 (Germany); Max Planck Institute for Biophysical Chemistry, Göttingen 37077 (Germany); Rahinov, Igor [Department of Natural Sciences, The Open University of Israel, Ra' anana 4353701 (Israel); Auerbach, Daniel J. [Institute for Physical Chemistry, Georg August University of Göttingen, Göttingen 37077 (Germany); Max Planck Institute for Biophysical Chemistry, Göttingen 37077 (Germany); Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106 (United States)

    2014-01-28

    We present a combined experimental and theoretical study of NO(v = 3 → 3, 2, 1) scattering from a Au(111) surface at incidence translational energies ranging from 0.1 to 1.2 eV. Experimentally, molecular beam–surface scattering is combined with vibrational overtone pumping and quantum-state selective detection of the recoiling molecules. Theoretically, we employ a recently developed first-principles approach, which employs an Independent Electron Surface Hopping (IESH) algorithm to model the nonadiabatic dynamics on a Newns-Anderson Hamiltonian derived from density functional theory. This approach has been successful when compared to previously reported NO/Au scattering data. The experiments presented here show that vibrational relaxation probabilities increase with incidence energy of translation. The theoretical simulations incorrectly predict high relaxation probabilities at low incidence translational energy. We show that this behavior originates from trajectories exhibiting multiple bounces at the surface, associated with deeper penetration and favored (N-down) molecular orientation, resulting in a higher average number of electronic hops and thus stronger vibrational relaxation. The experimentally observed narrow angular distributions suggest that mainly single-bounce collisions are important. Restricting the simulations by selecting only single-bounce trajectories improves agreement with experiment. The multiple bounce artifacts discovered in this work are also present in simulations employing electronic friction and even for electronically adiabatic simulations, meaning they are not a direct result of the IESH algorithm. This work demonstrates how even subtle errors in the adiabatic interaction potential, especially those that influence the interaction time of the molecule with the surface, can lead to an incorrect description of electronically nonadiabatic vibrational energy transfer in molecule-surface collisions.

  6. Oxygen-induced restructuring with release of gold atoms from Au(111)

    Min, B.K.; Deng, X.; Schalek, R.; Pinnaduwage, D.; Friend, C.M.

    2005-01-01

    Adsorption of oxygen atoms, achieved via electron-induced dissociation of nitrogen dioxide, induces restructuring of the 'herringbone' to a striped, soliton-wall structure accompanied by release of gold from the 'elbows' in the herringbone structure. The number density of 'elbows' (dislocations corresponding to a change in direction of the reconstruction) decreases as a function of increasing atomic oxygen coverage while the long range order observed in low energy electron diffraction (LEED) changes from (√(3)x22)-rec. to (1x22) in the limit of saturation coverage. Small islands and serrated step edges were formed due to the release of gold atoms from elbow sites of Au(111). The overall structural change of the Au(111) surface may result from the reduction of anisotropy related to the tensile stress relief of the Au(111) surface by oxygen atoms

  7. Surface structure and morphology of Cu-free and Cu-covered Au(100) and Au(111) electrodes in alkaline solution

    Schlaup, Christian [Technical University of Denmark, Department of Physics, Fysikvey, DK-2800 Kongens Lyngby (Denmark); Friebel, Daniel [Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Rd, Menlo Park, CA 94025 (United States); Wandelt, Klaus [University of Bonn, Institute for Physical und Theoretical Chemistry, Wegelerstr. 12, D-53115 Bonn (Germany)

    2011-07-01

    For both Cu-free Au-electrodes three different phases were observed as a function of the applied electrode potential. While at low potentials the onset of surface reconstruction points towards an apparently adsorbate free surface and, thus, a weak interaction with species from the electrolyte, a Au-hydroxide and a Au-oxide phase are formed subsequently during potential increase. A similar phase behavior was also found for Cu-covered Au-electrodes, while at low potentials an apparently adsorbate free Cu layer is observed, a Cu-hydroxide coadsorbate phase and a Cu-oxide phase are formed under increased potential conditions. In addition the apparently adsorbate free Cu-film tends to form a Cu-Au alloy phase while keeping the electrode for a sufficient long time at low potential conditions.

  8. Coverage Dependent Assembly of Anthraquinone on Au(111)

    Conrad, Brad; Deloach, Andrew; Einstein, Theodore; Dougherty, Daniel

    A study of adsorbate-adsorbate and surface state mediated interactions of anthraquinone (AnQ) on Au(111) is presented. We utilize scanning tunneling microscopy (STM) to characterize the coverage dependence of AnQ structure formation. Ordered structures are observed up to a single monolayer (ML) and are found to be strongly dependent on molecular surface density. While the complete ML forms a well-ordered close-packed layer, for a narrow range of sub-ML coverages irregular close-packed islands are observed to coexist with a disordered pore network linking neighboring islands. This network displays a characteristic pore size and at lower coverages, the soliton walls of the herringbone reconstruction are shown to promote formation of distinct pore nanostructures. We will discuss these nanostructure formations in the context of surface mediated and more direct adsorbate interactions.

  9. RPBE-vdW Description of Benzene Adsorption on Au(111)

    Pedersen, Jess Wellendorff; Kelkkanen, Kari André; Mortensen, Jens Jørgen

    2010-01-01

    Density functional theory has become a popular methodology for the analysis of molecular adsorption on surfaces. Despite this popularity, there exist adsorption systems for which commonly used exchange-correlation functionals fail miserably. Particularly those systems where binding is due to van...... der Waals interactions. The adsorption of benzene on Au(111) is an often mentioned such system where standard density functionals predict a very weak adsorption or even a repulsion, whereas a significant adsorption is observed experimentally. We show that a considerable improvement in the description...... of the adsorption of benzene on Au(111) is obtained when using the so-called RPBE-vdW functional....

  10. Dynamics of decanethiol self-assembled monolayers on Au(111) studied by Scanning tunnelling microscopy

    Wu, Hairong; Sotthewes, Kai; Kumar, Avijit; Vancso, Gyula J.; Schön, Peter Manfred; Zandvliet, Henricus J.W.

    2013-01-01

    We investigated the dynamics of decanethiol self-assembled monolayers on Au(111) surfaces using time-resolved scanning tunneling microscopy at room temperature. The expected ordered phases (β, δ, χ*, and ) and a disordered phase (ε) were observed. Current–time traces with the feedback loop disabled

  11. Triptycene-terminated thiolate and selenolate monolayers on Au(111

    Jinxuan Liu

    2017-04-01

    Full Text Available To study the implications of highly space-demanding organic moieties on the properties of self-assembled monolayers (SAMs, triptycyl thiolates and selenolates with and without methylene spacers on Au(111 surfaces were comprehensively studied using ultra-high vacuum infrared reflection absorption spectroscopy, X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy and thermal desorption spectroscopy. Due to packing effects, the molecules in all monolayers are substantially tilted. In the presence of a methylene spacer the tilt is slightly less pronounced. The selenolate monolayers exhibit smaller defect densities and therefore are more densely packed than their thiolate analogues. The Se–Au binding energy in the investigated SAMs was found to be higher than the S–Au binding energy.

  12. Adsorptive behavior of dimethylglyoxime on Au(111).

    Kim, Jandee; Kim, Sechul; Rhee, Choong Kyun

    2011-12-06

    Dimethylglyoxime (DMG) adsorbed on Au(111) was investigated using electrochemical scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). STM experiments revealed three different structures of adsorbed DMG at open circuit potential (~0.07 V versus Ag/AgCl): (2√3×2√3)R30°-α, (2√3×4√3)R30°-β, and (2√3×4√3)R30°-γ. The coverage of adsorbed DMG obtained using XPS was 0.33. A combination of structural and quantitative information identified the adsorbed DMG as an anionic tetramer, held together by intermolecular hydrogen bonding and arrayed in three ordered patterns. Domains of adsorbed DMG underwent phase transitions between the observed structures, most likely due to the influence of the STM tip. However, a significant correlation between the observed structures and the imaging conditions was not found. The ordered layers existed only at open circuit potential as evidenced by their disappearance when the potential was shifted to 0.2 or -0.15 V. The ordered layers were also removed by immersion in a solution of Ni(2+), implying that the adsorbed DMG was converted to a soluble dimer complex with the Ni(2+) ion. This particular observation is discussed in terms of the rigidity of the organic network. © 2011 American Chemical Society

  13. Bis(triisopropylsilylethynyl)pentacene/Au(111) interface: Coupling, molecular orientation, and thermal stability

    Gnoli, Andrea; Ü stü nel, Hande; Toffoli, Daniele; Yu, Liyang; Catone, D.; Turchini, Stefano; Lizzit, Silvano; Stingelin, Natalie; Larciprê te, Rosanna

    2014-01-01

    The assembly and the orientation of functionalized pentacene at the interface with inorganics strongly influence both the electric contact and the charge transport in organic electronic devices. In this study electronic spectroscopies and theoretical modeling are combined to investigate the properties of the bis(triisopropylsilylethynyl)pentacene (TIPS-Pc)/Au(111) interface as a function of the molecular coverage to compare the molecular state in the gas phase and in the adsorbed phase and to determine the thermal stability of TIPS-Pc in contact with gold. Our results show that in the free molecule only the acene atoms directly bonded to the ligands are affected by the functionalization. Adsorption on Au(111) leads to a weak coupling which causes only modest binding energy shifts in the TIPS-Pc and substrate core level spectra. In the first monolayer the acene plane form an angle of 33 ± 2° with the Au(111) surface at variance with the vertical geometry reported for thicker solution-processed or evaporated films, whereas the presence of configurational disorder was observed in the multilayer. The thermal annealing of the TIPS-Pc/Au(111) interface reveals the ligand desorption at ∼470 K, which leaves the backbone of the decomposed molecule flat-lying on the metal surface as in the case of the unmodified pentacene. The weak interaction with the metal substrate causes the molecular dissociation to occur 60 K below the thermal decomposition taking place in thick drop-cast films.

  14. Bis(triisopropylsilylethynyl)pentacene/Au(111) interface: Coupling, molecular orientation, and thermal stability

    Gnoli, Andrea

    2014-10-02

    The assembly and the orientation of functionalized pentacene at the interface with inorganics strongly influence both the electric contact and the charge transport in organic electronic devices. In this study electronic spectroscopies and theoretical modeling are combined to investigate the properties of the bis(triisopropylsilylethynyl)pentacene (TIPS-Pc)/Au(111) interface as a function of the molecular coverage to compare the molecular state in the gas phase and in the adsorbed phase and to determine the thermal stability of TIPS-Pc in contact with gold. Our results show that in the free molecule only the acene atoms directly bonded to the ligands are affected by the functionalization. Adsorption on Au(111) leads to a weak coupling which causes only modest binding energy shifts in the TIPS-Pc and substrate core level spectra. In the first monolayer the acene plane form an angle of 33 ± 2° with the Au(111) surface at variance with the vertical geometry reported for thicker solution-processed or evaporated films, whereas the presence of configurational disorder was observed in the multilayer. The thermal annealing of the TIPS-Pc/Au(111) interface reveals the ligand desorption at ∼470 K, which leaves the backbone of the decomposed molecule flat-lying on the metal surface as in the case of the unmodified pentacene. The weak interaction with the metal substrate causes the molecular dissociation to occur 60 K below the thermal decomposition taking place in thick drop-cast films.

  15. Extraordinary epitaxial alignment of graphene islands on Au(111)

    Wofford, Joseph M; Dubon, Oscar D; Starodub, Elena; Nie Shu; Bartelt, Norman C; Thürmer, Konrad; McCarty, Kevin F; Walter, Andrew L; Bostwick, Aaron; Rotenberg, Eli

    2012-01-01

    Pristine, single-crystalline graphene displays a unique collection of remarkable electronic properties that arise from its two-dimensional, honeycomb structure. Using in situ low-energy electron microscopy, we show that when deposited on the (111) surface of Au carbon forms such a structure. The resulting monolayer, epitaxial film is formed by the coalescence of dendritic graphene islands that nucleate at a high density. Over 95% of these islands can be identically aligned with respect to each other and to the Au substrate. Remarkably, the dominant island orientation is not the better lattice-matched 30° rotated orientation but instead one in which the graphene [01] and Au [011] in-plane directions are parallel. The epitaxial graphene film is only weakly coupled to the Au surface, which maintains its reconstruction under the slightly p-type doped graphene. The linear electronic dispersion characteristic of free-standing graphene is retained regardless of orientation. That a weakly interacting, non-lattice matched substrate is able to lock graphene into a particular orientation is surprising. This ability, however, makes Au(111) a promising substrate for the growth of single crystalline graphene films. (paper)

  16. Controlling the stereochemistry and regularity of butanethiol self-assembled monolayers on Au(111)

    Yan, Jiawei; Ouyang, Runhai; Jensen, Palle Skovhus

    2014-01-01

    The rich stereochemistry of the self-assembled monolayers (SAMs) of four butanethiols on Au(111) is described, the SAMs containing up to 12 individual C, S, or Au chiral centers per surface unit cell. This is facilitated by synthesis of enantiomerically pure 2-butanethiol (the smallest unsubstitu......The rich stereochemistry of the self-assembled monolayers (SAMs) of four butanethiols on Au(111) is described, the SAMs containing up to 12 individual C, S, or Au chiral centers per surface unit cell. This is facilitated by synthesis of enantiomerically pure 2-butanethiol (the smallest...... when R is achiral, while adatom binding leads to rectangular plane groups that suppress long-range expression of chirality. Binding as RS• also inhibits the pitting intrinsically associated with adatom binding, desirably producing more regularly structured SAMs....

  17. Monolayer Iron Carbide Films on Au(111) as a Fischer–Tropsch Model Catalyst

    Mannie, Gilbère; Lammich, Lutz; Li, Yong-Wang

    2014-01-01

    -temperature exposure of Fe islands gas to C2H4 deposited on the clean Au(111) surface results in partly converted Fe/FexCy islands. Multistep flash-heating treatment of the partly converted Fe/FexCy islands at 523 and 773 K results in pure highly crystalline FexCy islands with in-plane nearest-neighbor distances of 0...

  18. Ab initio molecular dynamics calculations on scattering of hyperthermal H atoms from Cu(111) and Au(111)

    Kroes, Geert-Jan, E-mail: g.j.kroes@chem.leidenuniv.nl; Pavanello, Michele [Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden (Netherlands); Blanco-Rey, María [Departamento de Física de Materiales, Facultad de Químicas UPV/EHU, Apartado 1072, 20080 Donostia-San Sebastián (Spain); Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián (Spain); Alducin, Maite [Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián (Spain); Centro de Física de Materiales, Centro Mixto CSIC-UPV/EHU, Paseo Manuel de Lardizabal 5, 20018 Donostia-San Sebastián (Spain); Auerbach, Daniel J. [Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden (Netherlands); Max Planck Institute for Biophysical Chemistry, Göttingen (Germany); Institute for Physical Chemistry, Georg-August University of Göttingen, Göttingen (Germany)

    2014-08-07

    Energy loss from the translational motion of an atom or molecule impinging on a metal surface to the surface may determine whether the incident particle can trap on the surface, and whether it has enough energy left to react with another molecule present at the surface. Although this is relevant to heterogeneous catalysis, the relative extent to which energy loss of hot atoms takes place to phonons or electron-hole pair (ehp) excitation, and its dependence on the system's parameters, remain largely unknown. We address these questions for two systems that present an extreme case of the mass ratio of the incident atom to the surface atom, i.e., H + Cu(111) and H + Au(111), by presenting adiabatic ab initio molecular dynamics (AIMD) predictions of the energy loss and angular distributions for an incidence energy of 5 eV. The results are compared to the results of AIMDEFp calculations modeling energy loss to ehp excitation using an electronic friction (“EF”) model applied to the AIMD trajectories, so that the energy loss to the electrons is calculated “post” (“p”) the computation of the AIMD trajectory. The AIMD calculations predict average energy losses of 0.38 eV for Cu(111) and 0.13-0.14 eV for Au(111) for H-atoms that scatter from these surfaces without penetrating the surface. These energies closely correspond with energy losses predicted with Baule models, which is suggestive of structure scattering. The predicted adiabatic integral energy loss spectra (integrated over all final scattering angles) all display a lowest energy peak at an energy corresponding to approximately 80% of the average adiabatic energy loss for non-penetrative scattering. In the adiabatic limit, this suggests a way of determining the approximate average energy loss of non-penetratively scattered H-atoms from the integral energy loss spectrum of all scattered H-atoms. The AIMDEFp calculations predict that in each case the lowest energy loss peak should show additional energy

  19. Ab initio molecular dynamics calculations on scattering of hyperthermal H atoms from Cu(111) and Au(111).

    Kroes, Geert-Jan; Pavanello, Michele; Blanco-Rey, María; Alducin, Maite; Auerbach, Daniel J

    2014-08-07

    Energy loss from the translational motion of an atom or molecule impinging on a metal surface to the surface may determine whether the incident particle can trap on the surface, and whether it has enough energy left to react with another molecule present at the surface. Although this is relevant to heterogeneous catalysis, the relative extent to which energy loss of hot atoms takes place to phonons or electron-hole pair (ehp) excitation, and its dependence on the system's parameters, remain largely unknown. We address these questions for two systems that present an extreme case of the mass ratio of the incident atom to the surface atom, i.e., H + Cu(111) and H + Au(111), by presenting adiabatic ab initio molecular dynamics (AIMD) predictions of the energy loss and angular distributions for an incidence energy of 5 eV. The results are compared to the results of AIMDEFp calculations modeling energy loss to ehp excitation using an electronic friction ("EF") model applied to the AIMD trajectories, so that the energy loss to the electrons is calculated "post" ("p") the computation of the AIMD trajectory. The AIMD calculations predict average energy losses of 0.38 eV for Cu(111) and 0.13-0.14 eV for Au(111) for H-atoms that scatter from these surfaces without penetrating the surface. These energies closely correspond with energy losses predicted with Baule models, which is suggestive of structure scattering. The predicted adiabatic integral energy loss spectra (integrated over all final scattering angles) all display a lowest energy peak at an energy corresponding to approximately 80% of the average adiabatic energy loss for non-penetrative scattering. In the adiabatic limit, this suggests a way of determining the approximate average energy loss of non-penetratively scattered H-atoms from the integral energy loss spectrum of all scattered H-atoms. The AIMDEFp calculations predict that in each case the lowest energy loss peak should show additional energy loss in the

  20. Self-organization of S adatoms on Au(111): √3R30° rows at low coverage.

    Walen, Holly; Liu, Da-Jiang; Oh, Junepyo; Lim, Hyunseob; Evans, J W; Kim, Yousoo; Thiel, P A

    2015-07-07

    Using scanning tunneling microscopy, we observe an adlayer structure that is dominated by short rows of S atoms, on unreconstructed regions of a Au(111) surface. This structure forms upon adsorption of low S coverage (less than 0.1 monolayer) on a fully reconstructed clean surface at 300 K, then cooling to 5 K for observation. The rows adopt one of three orientations that are rotated by 30° from the close-packed directions of the Au(111) substrate, and adjacent S atoms in the rows are separated by √3 times the surface lattice constant, a. Monte Carlo simulations are performed on lattice-gas models, derived using a limited cluster expansion based on density functional theory energetics. Models which include long-range pairwise interactions (extending to 5a), plus selected trio interactions, successfully reproduce the linear rows of S atoms at reasonable temperatures.

  1. Self-organization of S adatoms on Au(111): √3R30° rows at low coverage

    Walen, Holly, E-mail: hwalen@iastate.edu [Department of Chemistry, Iowa State University, Ames, Iowa 50011 (United States); Liu, Da-Jiang [Ames Laboratory of the USDOE, Ames, Iowa 50011 (United States); Oh, Junepyo; Lim, Hyunseob; Kim, Yousoo [RIKEN Surface and Interface Science Laboratory, Wako, Saitama 351-0198 (Japan); Evans, J. W. [Ames Laboratory of the USDOE, Ames, Iowa 50011 (United States); Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States); Thiel, P. A. [Department of Chemistry, Iowa State University, Ames, Iowa 50011 (United States); Ames Laboratory of the USDOE, Ames, Iowa 50011 (United States); Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011 (United States)

    2015-07-07

    Using scanning tunneling microscopy, we observe an adlayer structure that is dominated by short rows of S atoms, on unreconstructed regions of a Au(111) surface. This structure forms upon adsorption of low S coverage (less than 0.1 monolayer) on a fully reconstructed clean surface at 300 K, then cooling to 5 K for observation. The rows adopt one of three orientations that are rotated by 30° from the close-packed directions of the Au(111) substrate, and adjacent S atoms in the rows are separated by √3 times the surface lattice constant, a. Monte Carlo simulations are performed on lattice-gas models, derived using a limited cluster expansion based on density functional theory energetics. Models which include long-range pairwise interactions (extending to 5a), plus selected trio interactions, successfully reproduce the linear rows of S atoms at reasonable temperatures.

  2. Growth of Single- and Bilayer ZnO on Au(111) and Interaction with Copper

    Deng, Xingyi; Yao, Kun; Sun, Keju; Li, Wei-Xue; Lee, Junseok; Matranga, Christopher

    2013-05-02

    The stoichiometric single- and bi-layer ZnO(0001) have been prepared by reactive deposition of Zn on Au(111) and studied in detail with X-ray photoelectron spectroscopy, scanning tunneling microscopy, and density functional theory calculations. Both single- and bi-layer ZnO(0001) adopt a planar, graphite-like structure similar to freestanding ZnO(0001) due to the weak van der Waals interactions dominating their adhesion with the Au(111) substrate. At higher temperature, the single-layer ZnO(0001) converts gradually to bi-layer ZnO(0001) due to the twice stronger interaction between two ZnO layers than the interfacial adhesion of ZnO with Au substrate. It is found that Cu atoms on the surface of bi-layer ZnO(0001) are mobile with a diffusion barrier of 0.31 eV, and likely to agglomerate and form nanosized particles at low coverages; while Cu atoms tend to penetrate a single layer of ZnO(0001) with a barrier of 0.10 eV, resulting in a Cu free surface.

  3. Synthesis of Epitaxial Single-Layer MoS2 on Au(111).

    Grønborg, Signe S; Ulstrup, Søren; Bianchi, Marco; Dendzik, Maciej; Sanders, Charlotte E; Lauritsen, Jeppe V; Hofmann, Philip; Miwa, Jill A

    2015-09-08

    We present a method for synthesizing large area epitaxial single-layer MoS2 on the Au(111) surface in ultrahigh vacuum. Using scanning tunneling microscopy and low energy electron diffraction, the evolution of the growth is followed from nanoscale single-layer MoS2 islands to a continuous MoS2 layer. An exceptionally good control over the MoS2 coverage is maintained using an approach based on cycles of Mo evaporation and sulfurization to first nucleate the MoS2 nanoislands and then gradually increase their size. During this growth process the native herringbone reconstruction of Au(111) is lifted as shown by low energy electron diffraction measurements. Within the MoS2 islands, we identify domains rotated by 60° that lead to atomically sharp line defects at domain boundaries. As the MoS2 coverage approaches the limit of a complete single layer, the formation of bilayer MoS2 islands is initiated. Angle-resolved photoemission spectroscopy measurements of both single and bilayer MoS2 samples show a dramatic change in their band structure around the center of the Brillouin zone. Brief exposure to air after removing the MoS2 layer from vacuum is not found to affect its quality.

  4. STM study of C60F18 high dipole moment molecules on Au(111)

    Bairagi, K.; Bellec, A.; Chumakov, R. G.; Menshikov, K. A.; Lagoute, J.; Chacon, C.; Girard, Y.; Rousset, S.; Repain, V.; Lebedev, A. M.; Sukhanov, L. P.; Svechnikov, N. Yu.; Stankevich, V. G.

    2015-11-01

    Scanning tunneling microscopy and spectroscopy studies of C60F18 molecules deposited on Au(111) are reported and compared to C60 molecules both at liquid helium temperature and room temperature (RT). Whereas adsorption and electronic properties of C60F18 single molecules were studied at low temperature (LT), self-assemblies were investigated at RT. In both cases, the fluorine atoms of the C60F18 molecules are pointed towards the surface. Individual C60F18 molecules on Au(111) have a HOMO-LUMO gap of 2.9 eV. The self-assembled islands exhibit a close-packed hexagonal lattice with amorphous borders. The comparison with C60 molecules clearly demonstrates the influence of the C60F18 electric dipole moment (EDM) on the electronic properties of single molecules and on the thermodynamics of self-assembled islands. Besides, the apparent height value of a separate molecule increases in a self-assembly environment as a result of a depolarization phenomenon.

  5. In situ x-ray scattering studies of the Au(111)/electrolyte interface

    Wang, Jia; Ocko, B.M.; Davenport, A.J.; Isaacs, H.S.

    1991-01-01

    The adsorption of anions at the Au(111) electrode and the subsequent effect on the gold surface structure have been investigated using x-ray specular reflectivity and grazing incident angle diffraction techniques. The top layer of gold atoms undergoes a reversible phase transition between the (1x1) bulk termination and a (23x√ bar 3) reconstructed phase on changing the potential. The shifts of the phase transition potential in NaCland NaBr solutions from the one in NaF can be understood by the anion adsorption induced charge effect. The reconstruction formation rate increases in chloride and bromide solutions due to an increase in the surface mobility with anion adsorption. Adsorbed chloride and bromide monolayers can be monitored during a potential scan by the specular reflectivity

  6. Metal-organic extended 2D structures: Fe-PTCDA on Au(111)

    Alvarez, Lucia; Caillard, Renaud; MartIn-Gago, Jose A; Mendez, Javier; Pelaez, Samuel; Serena, Pedro A

    2010-01-01

    In this work we combine organic molecules of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) with iron atoms on an Au (111) substrate in ultra-high vacuum conditions at different temperatures. By means of scanning tunnelling microscopy (STM) we study the formation of stable 2D metal-organic structures. We show that at certain growth conditions (temperature, time and coverage) stable 'ladder-like' nanostructures are obtained. These are the result of connecting together two metal-organic chains through PTCDA molecules placed perpendicularly, as rungs of a ladder. These structures, stable up to 450 K, can be extended in a 2D layer covering the entire surface and presenting different rotation domains. STM images at both polarities show a contrast reversal between the two molecules at the unit cell. By means of density functional theory (DFT) calculations, we confirm the stability of these structures and that their molecular orbitals are placed separately at the different molecules.

  7. Organized monolayers of biological macromolecules on Au(111) surfaces

    Zhang, Jingdong; Chi, Qijin; Nielsen, Jens Ulrik

    2002-01-01

    Single-crystal electrochemistry and scanning tunneling microscopy directly in aqueous electrolyte solution (in situ STM) are established in physical electrochemistry but new in studies of adsorption and interfacial electrochemistry of biological macromolecules. These high-resolution techniques ha...

  8. An efficient Monte Carlo algorithm for the fast equilibration and atomistic simulation of alkanethiol self-assembled monolayers on a Au(111) substrate.

    Alexiadis, Orestis; Daoulas, Kostas Ch; Mavrantzas, Vlasis G

    2008-01-31

    A new Monte Carlo algorithm is presented for the simulation of atomistically detailed alkanethiol self-assembled monolayers (R-SH) on a Au(111) surface. Built on a set of simpler but also more complex (sometimes nonphysical) moves, the new algorithm is capable of efficiently driving all alkanethiol molecules to the Au(111) surface, thereby leading to full surface coverage, irrespective of the initial setup of the system. This circumvents a significant limitation of previous methods in which the simulations typically started from optimally packed structures on the substrate close to thermal equilibrium. Further, by considering an extended ensemble of configurations each one of which corresponds to a different value of the sulfur-sulfur repulsive core potential, sigmass, and by allowing for configurations to swap between systems characterized by different sigmass values, the new algorithm can adequately simulate model R-SH/Au(111) systems for values of sigmass ranging from 4.25 A corresponding to the Hautman-Klein molecular model (J. Chem. Phys. 1989, 91, 4994; 1990, 93, 7483) to 4.97 A corresponding to the Siepmann-McDonald model (Langmuir 1993, 9, 2351), and practically any chain length. Detailed results are presented quantifying the efficiency and robustness of the new method. Representative simulation data for the dependence of the structural and conformational properties of the formed monolayer on the details of the employed molecular model are reported and discussed; an investigation of the variation of molecular organization and ordering on the Au(111) substrate for three CH3-(CH2)n-SH/Au(111) systems with n=9, 15, and 21 is also included.

  9. Emergence of chirality in hexagonally packed monolayers of hexapentyloxytriphenylene on Au(111): a joint experimental and theoretical study.

    Sleczkowski, Piotr; Katsonis, Nathalie; Kapitanchuk, Oleksiy; Marchenko, Alexandr; Mathevet, Fabrice; Croset, Bernard; Lacaze, Emmanuelle

    2014-11-11

    We investigate the expression of chirality in a monolayer formed spontaneously by 2,3,6,7,10,11-pentyloxytriphenylene (H5T) on Au(111). We resolve its interface morphology by combining scanning tunneling microscopy (STM) with theoretical calculations of intermolecular and interfacial interaction potentials. We observe two commensurate structures. While both of them belong to a hexagonal space group, analogical to the triangular symmetry of the molecule and the hexagonal symmetry of the substrate surface, they surprisingly reveal a 2D chiral character. The corresponding breaking of symmetry arises for two reasons. First it is due to the establishment of a large molecular density on the substrate, which leads to a rotation of the molecules with respect to the molecular network crystallographic axes to avoid steric repulsion between neighboring alkoxy chains. Second it is due to the molecule-substrate interactions, leading to commensurable large crystallographic cells associated with the large size of the molecule. As a consequence, molecular networks disoriented with respect to the high symmetry directions of the substrate are induced. The high simplicity of the intermolecular and molecule-substrate van der Waals interactions leading to these observations suggests a generic character for this kind of symmetry breaking. We demonstrate that, for similar molecular densities, only two kinds of molecular networks are stabilized by the molecule-substrate interactions. The most stable network favors the interfacial interactions between terminal alkoxy tails and Au(111). The metastable one favors a specific orientation of the triphenylene core with its symmetry axes collinear to the Au⟨110⟩. This specific orientation of the triphenylene cores with respect to Au(111) appears associated with an energy advantage larger by at least 0.26 eV with respect to the disoriented core.

  10. A density functional theory study of the electronic properties of Os(II) and Os(III) complexes immobilized on Au(111)

    O'Boyle, N.M.; Albrecht, Tim; Murgida, D.H.

    2007-01-01

    We present a density functional theory (DFT) study of an osmium polypyridyl complex adsorbed on Au(111). The osmium polypyridyl complex [Os(bpy)(2)(P0P)Cl](n+) [bpy is 2,2'-bipyridine, P0P is 4,4'-bipyridine, n = 1 for osmium(II), and n = 2 for osmium(III)] is bound to the surface through the fre...

  11. Deformation of Ag clusters deposited on Au(111) - Experiment and molecular dynamics

    Miroslawski, Natalie; Groenhagen, Niklas; Hoevel, Heinz [TU Dortmund, Experimentelle Physik I (Germany); Issendorff, Bernd von [Universitaet Freiburg, Fakultaet Physik (Germany); Jaervi, Tommi [Fraunhofer Institut fuer Werkstoffmechanik, Freiburg (Germany); Moseler, Michael [Universitaet Freiburg, Fakultaet Physik (Germany); Fraunhofer Institut fuer Werkstoffmechanik, Freiburg (Germany); Freiburger Materialforschungszentrum (Germany)

    2011-07-01

    Mass selected clusters from Ag{sup +}{sub 55} to Ag{sup +}{sub 147{+-}}{sub 2} were deposited with different deposition energies at 77 K on Au(111) and imaged with STM at 77 K. We observed a deformation of the cluster shape due to the strong metallic interaction between the cluster and the substrate. The clusters became epitaxial and developed a structure composed of several Ag monolayers. The number of these monolayers depends on the number of atoms in the cluster and the deposition energy. The larger the cluster mass the more monolayers the cluster develops on Au(111) and the larger the deposition energy the fewer monolayers occur. These results were verified by molecular dynamic simulations. Additionally the behaviour of Ag{sub N} clusters on Au(111) after different annealing steps was investigated.

  12. Enhanced fullerene–Au(111 coupling in (2√3 × 2√3R30° superstructures with intermolecular interactions

    Michael Paßens

    2015-06-01

    Full Text Available Disordered and uniform (2√3 × 2√3R30° superstructures of fullerenes on the Au(111 surface have been studied using scanning tunneling microscopy and spectroscopy. It is shown that the deposition and growth process of a fullerene monolayer on the Au(111 surface determine the resulting superstructure. The supply of thermal energy is of importance for the activation of a Au vacancy forming process and thus, one criterion for the selection of the respective superstructure. However, here it is depicted that a vacancy–adatom pair can be formed even at room temperature. This latter process results in C60 molecules that appear slightly more bright in scanning tunnelling microscopy images and are identified in disordered (2√3 x 2√3R30° superstructures based on a detailed structure analysis. In addition, these slightly more bright C60 molecules form uniform (2√3 x 2√3R30° superstructures, which exhibit intermolecular interactions, likely mediated by Au adatoms. Thus, vacancy–adatom pairs forming at room temperature directly affect the resulting C60 superstructure. Differential conductivity spectra reveal a lifting of the degeneracy of the LUMO and LUMO+1 orbitals in the uniform (2√3 x 2√3R30° superstructure and in addition, hybrid fullerene–Au(111 surface states suggest partly covalent interactions.

  13. Hydrogen-bonded clusters of 1, 1'-ferrocenedicarboxylic acid on Au(111) are initially formed in solution

    Quardokus, Rebecca C.; Wasio, Natalie A.; Brown, Ryan D.; Christie, John A.; Henderson, Kenneth W.; Forrest, Ryan P.; Lent, Craig S.; Corcelli, Steven A.; Alex Kandel, S.

    2015-03-01

    Low-temperature scanning tunneling microscopy is used to observe self-assembled structures of ferrocenedicarboxylic acid (Fc(COOH)2) on the Au(111) surface. The surface is prepared by pulse-deposition of Fc(COOH)2 dissolved in methanol, and the solvent is evaporated before imaging. While the rows of hydrogen-bonded dimers that are common for carboxylic acid species are observed, the majority of adsorbed Fc(COOH)2 is instead found in six-molecule clusters with a well-defined and chiral geometry. The coverage and distribution of these clusters are consistent with a random sequential adsorption model, showing that solution-phase species are determinative of adsorbate distribution for this system under these reaction conditions.

  14. Binary molecular layers of C-60 and copper phthalocyanine on Au(111) : Self-organized nanostructuring

    Stöhr, Meike; Wagner, Thorsten; Gabriel, Markus; Weyers, Bastian; Möller, Rolf

    The binary molecular system of C-60 and copper phthalocyanine(CuPc) molecules has been investigated by scanning tunneling microscopy (STM) at room temperature and at 50 K. As substrate Au(111) was chosen. When C-60 and CuPc molecules are sequentially deposited, it is found that well-ordered domains

  15. Two-Dimensional Cysteine and Cystine Cluster Networks on Au(111) Disclosed by Voltammetry and in Situ Scanning Tunneling Microscopy

    Zhang, Jingdong; Chi, Qijin; Nielsen, Jens Ulrik

    2000-01-01

    Microscopic structures for molecular monolayers of L-cysteine and L-cystine assembled on Au(111) have been disclosed by employing electrochemistry and in situ scanning tunneling microscopy (STM). HighresolutionSTMimages show that the adlayers of both cyteine and cystine exhibit highly......-ordered networklike clusters with (3x3 6)R30° structure. By combining the surface coverage estimated from voltammetric data, each cluster is demonstrated to include six individual cysteine molecules or three cystine molecules. As a comparison, no cluster structure is observed for the 1-butanethiol adlayer prepared...... and examined under the same conditions as those for cysteine and cystine. This suggests that intermolecular and intramolecular hydrogen bonds among adsorbed cysteine or cystine molecules could be responsible for the origin of the cluster-network structures for the adlayers. Several models are proposed and used...

  16. Bonding and orientation of 1,4-benzenedimethanethiol on Au(111) prepared from solution and from gas phase

    Pasquali, L; Terzi, F; Zanardi, C; Seeber, R; Paolicelli, G; Mahne, N; Nannarone, S

    2007-01-01

    The orientation and bonding of 1,4-benzenedimethanethiol molecules on Au(111) is studied by means of x-ray and ultraviolet (UV) photoemission, x-ray absorption and metastable deexcitation spectroscopy. The organic films are prepared both from solution and by exposing the clean substrate to the vapours of the substance in an evacuated environment. This leads to two different growth modes: when self-assembled monolayers (SAMs) are prepared from solution, the molecules tend to form a bilayer film with the molecules standing upright and with the molecular axis forming an angle of about 30 0 with respect to the substrate normal; when growth is carried out from the gas phase, the molecules tend to assume at the earliest stages of exposure a flat-lying configuration, with both sulfur end-groups bonding to Au; at increasing exposure the surface coverage presents a saturation and the chemisorbed molecules tend to assume an upright arrangement

  17. Exchange interaction of strongly anisotropic tripodal erbium single-ion magnets with metallic surfaces

    Dreiser, Jan; Wäckerlin, Christian; Ali, Md. Ehesan

    2014-01-01

    We present a comprehensive study of Er(trensal) single-ion magnets deposited in ultrahigh vacuum onto metallic surfaces. X-ray photoelectron spectroscopy reveals that the molecular structure is preserved after sublimation, and that the molecules are physisorbed on Au(111) while they are chemisorbed...... on a Ni thin film on Cu(100) single-crystalline surfaces. X-ray magnetic circular dichroism (XMCD) measurements performed on Au(111) samples covered with molecular monolayers held at temperatures down to 4 K suggest that the easy axes of the strongly anisotropic molecules are randomly oriented...... pathways toward optical addressing of surface-deposited single-ion magnets....

  18. Organisation and Control of Nanoscale Structures on Au(111)

    Zhang, Jingdong; Chi, Qijin; Andersen, Jens Enevold Thaulov

    2001-01-01

    system is IDe arnino acid cystine in the adsorbed state. Af ter dissociation of its disulfide band cystine farms a highly ordered pattem controlled by adsorption via IDe liberated sulfur atoms and intermolecular hydrogen bonding. Further organisation at three different leveis by lateral interactions can...... constitutes a new case for the lise of in situ STM as a tool for manufacturing nanoscale pit structures on IDe Au(lll) surface at small bias voltage. Individually and in combination these data hold perspectives for preparation of atornically planar electrochernical surfaces willi controlled functionalisation...

  19. Monolayer Assemblies of a De Novo Designed 4-alpha-Helix Bundle Carboprotein and Its Sulfur Anchor Fragment on Au(111) Surfaces Addressed by Voltammetry and In Situ Scanning Tunneling Microscopy

    Brask, Jesper; Wackerbarth, Hainer; Jensen, Knud J.

    2003-01-01

    carboprotein without thiol anchor have been prepared and investigated for comparison. Cyclic and differential pulse voltammetry (DPV) of the proteins show desorption peaks around -750 mV (SCE), whereas the thiol anchor desorption peak is at -685 mV. The peaks are by far the highest for thiol monomeric 4-R...

  20. Molecular monolayers and interfacial electron transfer of pseudomonas aeruginosa azurin on Au(111)

    Chi, Qijin; Zhang, Jingdong; Nielsen, Jens Ulrik

    2000-01-01

    disulfide group to form a monolayer. The adsorption of this protein on Au(111) via a gold-sulfur binding mode is further supported by XPS measurements. In situ STM images with molecular resolution have been recorded and show a dense monolayer organization of adsorbed azurin molecules. Direct electron......We provide a comprehensive approach to the formation and characterization of molecular monolayers of the blue copper protein Pseudomonas aeruginosa azurin on Au(111) in aqueous ammonium acetate solution. Main issues are adsorption patterns, reductive desorption, properties of the double layer......, and long-range electrochemical electron transfer between the electrode and the copper center. Voltammetry, electrochemical impedance spectroscopy (EIS), in situ scanning tunneling microscopy (STM), and X-ray photoelectron spectroscopy (XPS) have been employed to disclose features of these issues. Zn...

  1. Ab initio simulations of scanning-tunneling-microscope images with embedding techniques and application to C58-dimers on Au(111).

    Wilhelm, Jan; Walz, Michael; Stendel, Melanie; Bagrets, Alexei; Evers, Ferdinand

    2013-05-14

    We present a modification of the standard electron transport methodology based on the (non-equilibrium) Green's function formalism to efficiently simulate STM-images. The novel feature of this method is that it employs an effective embedding technique that allows us to extrapolate properties of metal substrates with adsorbed molecules from quantum-chemical cluster calculations. To illustrate the potential of this approach, we present an application to STM-images of C58-dimers immobilized on Au(111)-surfaces that is motivated by recent experiments.

  2. Diffusion of 1,4-butanedithiol radicals on Au(111) and Au(100): A DFT-based comparison

    Franke, Andreas; Pehlke, Eckhard [Institut fuer Theoretische Physik und Astrophysik, Universitaet Kiel, 24098 Kiel (Germany)

    2010-07-01

    Organic molecules chemisorbed on surfaces hold the perspective of surface functionalization. The 1,4-butanedithiol radical chemisorbed at the Au(111) or Au(100) surface serves as a model system for the S-Au molecule-substrate bond. Density functional total-energy calculations have been carried out for the chemisorption of the radical on the unreconstructed Au surfaces, which are both known to be stabilized under electrochemical conditions. Local minima with close-by energies indicate multi-valley potential-energy surfaces, which originate from the interplay between the two S-Au adsorbate-substrate bonds and the internal degrees of freedom of the butanedithiol radical. Diffusion paths of the radical on both Au surfaces have been calculated within DFT using VASP. The diffusion barriers for translation and rotation of the radical differ. They can be fine-tuned by varying the applied potential in the electrochemical cell. This is considered theoretically by inspecting the variation of the dipole moment along the reaction paths. Consequences for the dynamics of succeeding diffusion hops are discussed.

  3. ATR-SEIRAS study of CO adsorption and oxidation on Rh modified Au(111-25 nm) film electrodes in 0.1 M H2SO4

    Xu, Qinqin; Berná, Antonio; Pobelov, Ilya V.; Rodes, Antonio; Feliu, Juan M.; Wandlowski, Thomas; Kuzume, Akiyoshi

    2015-01-01

    Rh modified Au(111-25 nm) electrodes, prepared by electron beam evaporation and galvanostatic deposition, were employed to study adsorption and electro-oxidation of CO on Rh in 0.1 M sulfuric acid solution by in situ attenuated total reflection surface enhanced infrared absorption spectroscopy (ATR-SEIRAS). The results of ATR-SEIRAS experiments were compared with those obtained by infrared reflection absorption spectroscopy on three low-index Rh single crystal surfaces. The Rh film deposited on Au(111-25 nm) electrode consists of 3D clusters forming a highly stepped [n(111) × (111)]-like surface with narrow (111) terraces. When CO was dosed at the hydrogen adsorption potential region, CO adsorbed in both atop (CO L ) and bridge (CO B ) configurations, as well as coadsorbed water species, were detected on the Rh film electrode. A partial interconversion of spectroscopic bands due to the CO displacement from bridge to atop sites was found during the anodic potential scan, revealing that there is a potential-dependent preference of CO adsorption sites on Rh surfaces. Our data indicate that CO oxidation on Rh electrode surface in acidic media involves coadsorbed water and follows the nucleation and growth model of a Langmuir-Hinshelwood type reaction

  4. Adsorption of the ionic liquid [BMP][TFSA] on Au(111 and Ag(111: substrate effects on the structure formation investigated by STM

    Benedikt Uhl

    2013-12-01

    Full Text Available In order to resolve substrate effects on the adlayer structure and structure formation and on the substrate–adsorbate and adsorbate–adsorbate interactions, we investigated the adsorption of thin films of the ionic liquid (IL 1-butyl-1-methylpyrrolidinium-bis(trifluoromethylsulfonylimide [BMP][TFSA] on the close-packed Ag(111 and Au(111 surfaces by scanning tunneling microscopy, under ultra high vacuum (UHV conditions in the temperature range between about 100 K and 293 K. At room temperature, highly mobile 2D liquid adsorbate phases were observed on both surfaces. At low temperatures, around 100 K, different adsorbed IL phases were found to coexist on these surfaces, both on silver and gold: a long-range ordered (‘2D crystalline’ phase and a short-range ordered (‘2D glass’ phase. Both phases exhibit different characteristics on the two surfaces. On Au(111, the surface reconstruction plays a major role in the structure formation of the 2D crystalline phase. In combination with recent density functional theory calculations, the sub-molecularly resolved STM images allow to clearly discriminate between the [BMP]+ cation and [TFSA]− anion.

  5. Azobenzene versus 3,3',5,5'-tetra-tert-butyl-azobenzene (TBA) at Au(111): characterizing the role of spacer groups.

    McNellis, Erik R; Bronner, Christopher; Meyer, Jörg; Weinelt, Martin; Tegeder, Petra; Reuter, Karsten

    2010-06-28

    We present large-scale density-functional theory (DFT) calculations and temperature programmed desorption measurements to characterize the structural, energetic and vibrational properties of the functionalized molecular switch 3,3',5,5'-tetra-tert-butyl-azobenzene (TBA) adsorbed at Au(111). Particular emphasis is placed on exploring the accuracy of the semi-empirical dispersion correction approach to semi-local DFT (DFT-D) in accounting for the substantial van der Waals component in the surface bonding. In line with previous findings for benzene and pure azobenzene at coinage metal surfaces, DFT-D significantly overbinds the molecule, but seems to yield an accurate adsorption geometry as far as can be judged from the experimental data. Comparing the trans adsorption geometry of TBA and azobenzene at Au(111) reveals a remarkable insensitivity of the structural and vibrational properties of the -N[double bond, length as m-dash]N- moiety. This questions the established view of the role of the bulky tert-butyl-spacer groups for the switching of TBA in terms of a mere geometric decoupling of the photochemically active diazo-bridge from the gold substrate.

  6. Sensitivity of photoelectron diffraction to conformational changes of adsorbed molecules: Tetra-tert-butyl-azobenzene/Au(111

    A. Schuler

    2017-01-01

    Full Text Available Electron diffraction is a standard tool to investigate the atomic structure of surfaces, interfaces, and adsorbate systems. In particular, photoelectron diffraction is a promising candidate for real-time studies of structural dynamics combining the ultimate time resolution of optical pulses and the high scattering cross-sections for electrons. In view of future time-resolved experiments from molecular layers, we studied the sensitivity of photoelectron diffraction to conformational changes of only a small fraction of molecules in a monolayer adsorbed on a metallic substrate. 3,3′,5,5′-tetra-tert-butyl-azobenzene served as test case. This molecule can be switched between two isomers, trans and cis, by absorption of ultraviolet light. X-ray photoelectron diffraction patterns were recorded from tetra-tert-butyl-azobenzene/Au(111 in thermal equilibrium at room temperature and compared to patterns taken in the photostationary state obtained by exposing the surface to radiation from a high-intensity helium discharge lamp. Difference patterns were simulated by means of multiple-scattering calculations, which allowed us to determine the fraction of molecules that underwent isomerization.

  7. Sulfur dimers adsorbed on Au(111) as building blocks for sulfur octomers formation: A density functional study

    Hernandez-Tamargo, Carlos E.; Montero-Alejo, Ana Lilian; Pujals, Daniel Codorniu; Mikosch, Hans; Hernández, Mayra P.

    2014-01-01

    Experimental scanning tunneling microscopy (STM) studies have shown for more than two decades rectangular formations when sulfur atoms are deposited on Au(111) surfaces. The precursors have ranged from simple molecules or ions, such as SO 2 gas or sulfide anions, to more complex organosulfur compounds. We investigated, within the framework of the Density Functional Theory, the structure of these rectangular patterns assuming them entirely composed of sulfur atoms as the experimental evidence suggests. The sulfur coverage at which the simulations were carried out (0.67 ML or higher) provoked that the sulfur-sulfur association had to be taken into account for achieving a good agreement between the sets of simulated and experimental STM images. A combination of four sulfur dimers per rectangular formation properly explained the trends obtained by the experimental STM analysis which were related with the rectangles' size and shape fluctuations together with sulfur-sulfur distances within these rectangles. Finally, a projected density of states analysis showed that the dimers were capable of altering the Au(5d) electronic states at the same level as atomic sulfur adsorbed at low coverage. Besides, sulfur dimers states were perfectly distinguished, whose presence near and above the Fermi level can explain both: sulfur-sulfur bond elongation and dimers stability when they stayed adsorbed on the surface at high coverage

  8. Sulfur dimers adsorbed on Au(111) as building blocks for sulfur octomers formation: A density functional study

    Hernandez-Tamargo, Carlos E.; Montero-Alejo, Ana Lilian [Laboratory of Computational and Theoretical Chemistry (LQCT), Faculty of Chemistry, Havana University, Havana 10400 (Cuba); Pujals, Daniel Codorniu [Higher Institute of Technologies and Applied Sciences (InSTEC), Havana 10400 (Cuba); Mikosch, Hans [Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9/E164-EC, 1060 Vienna (Austria); Hernández, Mayra P., E-mail: mayrap@imre.oc.uh.cu [Instituto de Ciencias y Tecnologías de Materiales (IMRE), Havana 10400 (Cuba)

    2014-07-28

    Experimental scanning tunneling microscopy (STM) studies have shown for more than two decades rectangular formations when sulfur atoms are deposited on Au(111) surfaces. The precursors have ranged from simple molecules or ions, such as SO{sub 2} gas or sulfide anions, to more complex organosulfur compounds. We investigated, within the framework of the Density Functional Theory, the structure of these rectangular patterns assuming them entirely composed of sulfur atoms as the experimental evidence suggests. The sulfur coverage at which the simulations were carried out (0.67 ML or higher) provoked that the sulfur-sulfur association had to be taken into account for achieving a good agreement between the sets of simulated and experimental STM images. A combination of four sulfur dimers per rectangular formation properly explained the trends obtained by the experimental STM analysis which were related with the rectangles' size and shape fluctuations together with sulfur-sulfur distances within these rectangles. Finally, a projected density of states analysis showed that the dimers were capable of altering the Au(5d) electronic states at the same level as atomic sulfur adsorbed at low coverage. Besides, sulfur dimers states were perfectly distinguished, whose presence near and above the Fermi level can explain both: sulfur-sulfur bond elongation and dimers stability when they stayed adsorbed on the surface at high coverage.

  9. The disclosure of mesoscale behaviour of a 3d-SMM monolayer on Au(111) through a multilevel approach.

    Fernandez Garcia, Guglielmo; Lunghi, Alessandro; Totti, Federico; Sessoli, Roberta

    2018-02-22

    Here we present a computational study of a full- and a half-monolayer of a Fe 4 single molecule magnet ([Fe 4 (L) 2 (dpm) 6 ], where H 3 L = 2-hydroxymethyl-2-phenylpropane-1,3-diol and Hdpm = dipivaloylmethane, Fe 4 Ph) on an unreconstructed surface of Au(111). This has been possible through the application of an integrated approach, which allows the explicit inclusion of the packing effects in the classical dynamics to be used in a second step in periodic and non-periodic high level DFT calculations. In this way we can obtain access to mesoscale geometrical data and verify how they can influence the magnetic properties of interest of the single Fe 4 molecule. The proposed approach allows to overcome the ab initio state-of-the-art approaches used to study Single Molecule Magnets (SMMs), which are based on the study of one single adsorbed molecule and cannot represent effects on the scale of a monolayer. Indeed, we show here that it is possible to go beyond the computational limitations inherent to the use, for such complex systems, of accurate calculation techniques (e.g. ab initio molecular dynamics) without losing the level of accuracy necessary to gain new detailed insights, hardly reachable at the experimental level. Indeed, long-range and edge effects on the Fe 4 structures and their easy axis of magnetization orientations have been evidenced as their different contributions to the overall macroscopic behavior.

  10. Switching and sensing spin states of co-porphyrin in bimolecular reactions on Au111 using scanning tunneling microscopy.

    Kim, Howon; Chang, Yun Hee; Lee, Soon-Hyeong; Kim, Yong-Hyun; Kahng, Se-Jong

    2013-10-22

    Controlling and sensing spin states of magnetic molecules at the single-molecule level is essential for spintronic molecular device applications. Here, we demonstrate that spin states of Co-porphyrin on Au(111) can be reversibly switched over by binding and unbinding of the NO molecule and can be sensed using scanning tunneling microscopy and spectroscopy (STM and STS). Before NO exposure, Co-porphryin showed a clear zero-bias peak, a signature of Kondo effect in STS, whereas after NO exposures, it formed a molecular complex, NO-Co-porphyrin, that did not show any zero-bias feature, implying that the Kondo effect was switched off by binding of NO. The Kondo effect could be switched back on by unbinding of NO through single-molecule manipulation or thermal desorption. Our density functional theory calculation results explain the observations with pairing of unpaired spins in dz(2) and ppπ* orbitals of Co-porphyrin and NO, respectively. Our study opens up ways to control molecular spin state and Kondo effect by means of enormous variety of bimolecular binding and unbinding reactions on metallic surfaces.

  11. Stick–slip behaviour on Au(111 with adsorption of copper and sulfate

    Nikolay Podgaynyy

    2015-03-01

    Full Text Available Several transitions in the friction coefficient with increasing load are found on Au(111 in sulfuric acid electrolyte containing Cu ions when a monolayer (or submonolayer of Cu is adsorbed. At the corresponding normal loads, a transition to double or multiple slips in stick–slip friction is observed. The stick length in this case corresponds to multiples of the lattice distance of the adsorbed sulfate, which is adsorbed in a √3 × √7 superstructure on the copper monolayer. Stick–slip behaviour for the copper monolayer as well as for 2/3 coverage can be observed at FN ≥ 15 nN. At this normal load, a change from a small to a large friction coefficient occurs. This leads to the interpretation that the tip penetrates the electrochemical double layer at this point. At the potential (or point of zero charge (pzc, stick–slip resolution persists at all normal forces investigated.

  12. Revisiting the adsorption of copper-phthalocyanine on Au(111) including van der Waals corrections

    Lüder, Johann; Eriksson, Olle; Sanyal, Biplab; Brena, Barbara

    2014-01-01

    We have studied the adsorption of copper-phthalocyanine on Au(111) by means of van der Waals corrected density functional theory using the Tkatchenko-Scheffler method. We have compared the element and site resolved adsorption distances to recent experimental normal-incident X-ray standing wave measurements. The measured adsorption distances could be reproduced within a deviation of 1% for the Cu atom, 1% for the C atoms, and 2% for the N atoms. The molecule was found to have a magnetic moment of 1 μ B distributed over the Cu and the N atoms of the pyrrole ring. Simulated scanning tunnel microscopy images based on the total and on the spin-resolved differential charge densities are provided for bias voltages of −1.45 and 1.45 eV

  13. State-to-state time-of-flight measurements of NO scattering from Au(111): direct observation of translation-to-vibration coupling in electronically nonadiabatic energy transfer.

    Golibrzuch, Kai; Shirhatti, Pranav R; Altschäffel, Jan; Rahinov, Igor; Auerbach, Daniel J; Wodtke, Alec M; Bartels, Christof

    2013-09-12

    Translational motion is believed to be a spectator degree of freedom in electronically nonadiabatic vibrational energy transfer between molecules and metal surfaces, but the experimental evidence available to support this view is limited. In this work, we have experimentally determined the translational inelasticity in collisions of NO molecules with a single-crystal Au(111) surface-a system with strong electronic nonadiabaticity. State-to-state molecular beam surface scattering was combined with an IR-UV double resonance scheme to obtain high-resolution time-of-flight data. The measurements include vibrationally elastic collisions (v = 3→3, 2→2) as well as collisions where one or two quanta of molecular vibration are excited (2→3, 2→4) or de-excited (2→1, 3→2, 3→1). In addition, we have carried out comprehensive measurements of the effects of rotational excitation on the translational energy of the scattered molecules. We find that under all conditions of this work, the NO molecules lose a large fraction (∼0.45) of their incidence translational energy to the surface. Those molecules that undergo vibrational excitation (relaxation) during the collision recoil slightly slower (faster) than vibrationally elastically scattered molecules. The amount of translational energy change depends on the surface temperature. The translation-to-rotation coupling, which is well-known for v = 0→0 collisions, is found to be significantly weaker for vibrationally inelastic than elastic channels. Our results clearly show that the spectator view of the translational motion in electronically nonadiabatic vibrational energy transfer between NO and Au(111) is only approximately correct.

  14. In situ observation of a deprotonation driven phase transformation-4,4'-Biphenyldicarboxylic acide on Au(111)

    Schwarz, Daniel; van Gastel, Raoul; Zandvliet, Henricus J.W.; Poelsema, Bene

    2013-01-01

    We have studied the growth of 4,4′-biphenyldicarboxylic acid (BDA) domains on Au(111) by means of low-energy electron microscopy (LEEM) and selective area low-energy electron diffraction (μLEED). Between 300 and 400 K, BDA forms three different 2-D crystalline phases, which are attributed to

  15. On the influence of the aliphatic linker on fabrication of highly ordered and orientated self-assembled monolayers of aromatic selenols on AU(111)

    Azzam, Waleed

    2014-03-06

    Self-assembled monolayers (SAMs) formed by adsorption of 1,2-dibenzyldiselenide (DPMSe) and 1,2-diphenyldiselenide (DBSe) on Au(111) substrates at room temperature have been characterized using scanning tunnelling microscopy, X-ray photoelectron spectroscopy, infrared reflection absorption spectroscopy, near-edge X-ray absorption fine structure spectroscopy, and low-energy electron diffraction. Upon adsorption, the Se-Se bonds in DPMSe and DBSe were cleaved on the gold surface to form phenylmethaneselenolate (PMSe) and benzeneselenolate (BSe) species, respectively. Although both PMSe and BSe molecular entities only differ in their structure (an additional methyl group in PMSe), the resulting monolayer films revealed noteworthy dissimilarities regarding their adlayer SAM structure and surface morphology. The molecular adlayer structure and orientation of PMSe and BSe species were found to vary significantly with the immersion time (IT). The resulting PMSe films were poorly organized, and the structure was described by a (4√3 × 2) rectangular unit cell for the SAMs prepared with 24 h of IT. Moreover, the PMSe-SAMs were found to be unstable upon exposure to air for a long time. Our results showed that exposure to air for 48 h results in the formation of small bright ad-islands, which have a height corresponding to that of a single atomic step on the Au(111). Contrary, BSe-SAMs exhibited densely packed and well-ordered monolayers, and two different structural phases were resolved at short and long ITs. The most densely packed structure was obtained for SAMs prepared with very short ITs (10 min). Upon increasing the IT, the SAMs exhibited structural changes to a lower density of molecular packing structure. The spectroscopic data also confirmed this structural transformation by suggesting an upright orientation for BSe-SAMs prepared after short ITs and strongly inclined adsorption geometry for SAMs prepared after long ITs. © 2014 American Chemical Society.

  16. Influence of the solution pH in the 6-mercaptopurine self-assembled monolayer (6MP-SAM) on a Au(111) single-crystal electrode.

    Madueño, Rafael; García-Raya, Daniel; Viudez, Alfonso J; Sevilla, José M; Pineda, Teresa; Blázquez, Manuel

    2007-10-23

    Self-assembled monolayers (SAMs) of 6-mercaptopurine (6MP) have been prepared on a Au(111) single-crystal electrode by immersion of the metal surface in a 100 microM 6MP and 0.01 M HClO4 solution. The 6MP-SAM Au(111) single-crystal electrodes were transferred to the cell and allowed to equilibrate with the different aqueous working solutions before the electrochemical experiments. The influence of the solution pH was studied by cyclic voltammetry, double layer capacitance curves, and electrochemical impedance spectroscopy. The electrochemical behavior of the 6MP-SAM in acetic acid at pH 4 presents important differences in comparison to that obtained in 0.1 M KOH solutions. Cyclic voltammograms for the reductive desorption process in acid medium are broad and show some features that can be explained by a phase transition between a chemisorbed and a physisorbed state of the 6MP molecules. The low solubility of these molecules in acid medium could explain this phenomenon and the readsorption of the complete monolayer when the potential is scanned in the positive direction. The variation of the double-layer capacitance values in the potential range of monolayer stability with the pH suggests that the acid-base chemistry of the 6MP molecules is playing a role. This fact has been studied by following the variations of the electron-transfer rate constant of the highly charged redox probes as are Fe(CN)(6)-3/-4 and Ru(NH3)(6)+3/+2 as a function of solution pH. The apparent surface pKa value for the 6MP-SAM (pKa approximately 8) is explained by the total conversion of the different 6MP tautomers that exist in solution to the thiol species in the adsorbed state.

  17. Electronic structure and electron dynamics at an organic molecule/metal interface: interface states of tetra-tert-butyl-imine/Au(111)

    Hagen, Sebastian; Wolf, Martin; Tegeder, Petra; Luo Ying; Haag, Rainer

    2010-01-01

    Time- and angle-resolved two-photon photoemission (2PPE) spectroscopies have been used to investigated the electronic structure, electron dynamics and localization at the interface between tetra-tert-butyl imine (TBI) and Au(111). At a TBI coverage of one monolayer (ML), the two highest occupied molecular orbitals, HOMO and HOMO-1, are observed at an energy of -1.9 and -2.6 eV below the Fermi level (E F ), respectively, and coincide with the d-band features of the Au substrate. In the unoccupied electronic structure, the lowest unoccupied molecular orbital (LUMO) has been observed at 1.6 eV with respect to E F . In addition, two delocalized states that arise from the modified image potential at the TBI/metal interface have been identified. Their binding energies depend strongly on the adsorption structure of the TBI adlayer, which is coverage dependent in the submonolayer (≤1 ML) regime. Thus the binding energy of the lower interface state (IS) shifts from 3.5 eV at 1.0 ML to 4.0 eV at 0.5 ML, which is accompanied by a pronounced decrease in its lifetime from 100 fs to below 10 fs. This is a result of differences in the wave function overlap with electronic states of the Au(111) substrate at different binding energies. This study shows that in order to fully understand the electronic structure of organic adsorbates at metal surfaces, not only adsorbate- and substrate-induced electronic states have to be considered but also ISs, which are the result of a potential formed by the interaction between the adsorbate and the substrate.

  18. Direct Adsorption and Molecular Self-Assembly of Octylthioacetates on Au(111) in the Vapor Phase

    Park, Tae Sung; Kang, Hun Gu; Kim, You Young; Lee, Seong Keun; Noh, Jae Geun

    2011-01-01

    We demonstrate that the direct adsorption of OTA on Au(111) in ethanol solution led to the formation of a disordered phase, whereas OTA SAMs grown from the vapor phase have an ordered 5 Χ √3 striped phase. Thus, vapor deposition was found to be a more effective technique, as compared to solution deposition, for improving the structural order of SAMs by direct adsorption of thioacetates on gold. Organic thiols are prone to easily oxidize to disulfides or other oxidized species that can affect the formation and structure of SAMs. The presence of disulfides or oxidized compounds in thiol samples often yields poorly ordered SAMs containing a high defect density and disordered phases. An approach that minimizes undesirable thiol oxidation is the use of a protected thiol that is deprotected in situ before or during SAM formation. The protection of thiol groups can be readily accomplished by acetylation. SAMs derived from acetyl protected thiols (thioacetates) on gold have usually been formed via an in situ deprotection process of the acetyl group in strong acidic or basic solutions. Other deprotection techniques have also been developed that use organic compounds such as triethylamine, tetrabutylammonium cyanide, and 1,8-diazabicyclo[5.4.0]undec-7-ene, and organic SAMs with a high degree of structural order have been successfully constructed in solutions containing these deprotection reagents

  19. Electrodéposition et la caractérisation de nanofilms palladium sur Au (111) pour le stockage d'hydrogène Electro-deposition and characterization of palladium nanofilms on Au (111) for hydrogen storage

    Wang , Liang

    2012-01-01

    This thesis focused on electro-deposition, characterization andhydrogen strorage of ultrathin palladium film over Au(111). Theelectrochemical characterization of the nanofilms in sulphuric mediumshows well-defined features evolving with the deposit thickness. Wecould assign each peak to a specific reaction, in agreement with thegrowth mechanisms revealed by in situ SXRD measurements. Thepseudomorphic growth of the 1st layer firstly undergoes an adsorptionstep, followed by nucleation and growt...

  20. Magnetism of coherent Co and Ni thin films on Cu(111) and Au(111) substrates: An ab initio study

    Zelený, Martin, E-mail: zeleny@fme.vutbr.cz; Dlouhý, Ivo

    2017-02-15

    We present an ab initio study of structural and magnetic properties of coherent Co and Ni thin films on Cu(111) and Au(111) substrates with thicknesses of up to 6 monolayers. All studied films on Cu(111) substrates prefer structures close their ground state (hcp for Co and fcc for Ni), whereas only the hcp stacking sequence has been found for both films on Au(111) substrates. All studied films exhibit instability of the first monolayer with respect to decomposition into 2-monolayer- or 3-monolayer-high islands, which is in agreement with experimental findings. All studied films are also ferromagnetic, nevertheless the Ni/Cu(111) films reduce their magnetic moments in the layer adjacent to the substrate due to a stronger Cu–Ni interaction at the interface. The magnetic anisotropy of a Co film does not depend on the film thickness: all the studied Co/Au(111) films exhibit a perpendicular magnetic anisotropy, whereas all the Co/Cu(111) films prefer in-plane magnetization. On the other hand, both Ni films change their preference for in-plane orientation of their easy axis to out-of-plane orientation at a critical thickness of 2 monolayers, however, the magnetic anisotropy energies for films thicker than 1 monolayer are smaller than 1 meV/Ni atom. These behaviors of magnetic anisotropy do not depend on the structure of the studied films. - Highlights: • All films exhibit instability of the first monolayer and prefer grow in islands. • The Cu–Ni interaction is responsible for reduced Ni magnetic moments in Ni/Cu(111) films. • The Co/Au(111) and Co/Cu(111) films show different orientations of magnetic anisotropy. • The Ni films exhibit in-plane magnetization only for single monolayer. • Behaviors of magnetic anisotropy do not depend on the structure of the studied films.

  1. Molecular Assembly of Hemin on Single-Crystal Au(111)-electrode Surfaces

    Zhang, Ling; Ulstrup, Jens; Zhang, Jingdong

    Iron porphyrin, hemin, is the active core in cytochromes, haemoglobin and myoglobin, andenzymes such as the peroxidases. These metalloproteins are engaged in respiratory electron transfer, oxygen transport and storage, and enzyme catalysis in the biosynthesis of a range of metabolites. Hemin itse...

  2. Electrochemistry of Single Metalloprotein and DNA‐Based Molecules at Au(111) Electrode Surfaces

    Salvatore, Princia; Zeng, Dongdong; Karlsen, Kasper Kannegård

    2013-01-01

    We have briefly overviewed recent efforts in the electrochemistry of single transition metal complex, redox metalloprotein, and redox‐marked oligonucleotide (ON) molecules. We have particularly studied self‐assembled molecular monolayers (SAMs) of several 5′‐C6‐SH single‐ (ss) and double‐strand (...

  3. An axis-specific rotational rainbow in the direct scatter of formaldehyde from Au(111) and its influence on trapping probability.

    Park, G Barratt; Krüger, Bastian C; Meyer, Sven; Kandratsenka, Alexander; Wodtke, Alec M; Schäfer, Tim

    2017-08-02

    The conversion of translational to rotational motion often plays a major role in the trapping of small molecules at surfaces, a crucial first step for a wide variety chemical processes that occur at gas-surface interfaces. However, to date most quantum-state resolved surface scattering experiments have been performed on diatomic molecules, and little detailed information is available about how the structure of nonlinear polyatomic molecules influences the mechanisms for energy exchange with surfaces. In the current work, we employ a new rotationally resolved 1 + 1' resonance-enhanced multiphoton ionization (REMPI) scheme to measure the rotational distribution in formaldehyde molecules directly scattered from the Au(111) surface at incidence kinetic energies in the range 0.3-1.2 eV. The results indicate a pronounced propensity to excite a-axis rotation (twirling) rather than b- or c-axis rotation (tumbling or cartwheeling), and are consistent with a rotational rainbow scattering model. Classical trajectory calculations suggest that the effect arises-to zeroth order-from the three-dimensional shape of the molecule (steric effects). Analysis suggests that the high degree of rotational excitation has a substantial influence on the trapping probability of formaldehyde at incidence translational energies above 0.5 eV.

  4. C6H6/Au(111): Interface dipoles, band alignment, charging energy, and van der Waals interaction

    Abad, E.; Martinez, J. I.; Flores, F.; Ortega, J.; Dappe, Y. J.

    2011-01-01

    We analyze the benzene/Au(111) interface taking into account charging energy effects to properly describe the electronic structure of the interface and van der Waals interactions to obtain the adsorption energy and geometry. We also analyze the interface dipoles and discuss the barrier formation as a function of the metal work-function. We interpret our DFT calculations within the induced density of interface states (IDIS) model. Our results compare well with experimental and other theoretical results, showing that the dipole formation of these interfaces is due to the charge transfer between the metal and benzene, as described in the IDIS model.

  5. Identification of Non-Faradaic Processes by Measurement of the Electrochemical Peltier Heat during the Silver Underpotential Deposition on Au(111).

    Frittmann, Stefan; Halka, Vadym; Schuster, Rolf

    2016-04-04

    We measured the heat which is reversibly exchanged during the course of an electrochemical surface reaction, i.e., the deposition/dissolution of the first two monolayers of Ag on a Au(111) surface in (bi)sulfate and perchlorate containing electrolytes. The reversibly exchanged heat corresponds to the Peltier heat of the reaction and is linearly related to its entropy change, including also non-Faradaic side processes. Hence, the measurement of the Peltier heat provides thermodynamic information on the electrochemical processes which is complementary to the current-potential relations usually obtained by conventional electrochemical methods. From the variation of the molar Peltier heat during the various stages of the deposition reaction we inferred that co-adsorption processes of anions and Ag do not play a prominent role, while we find strong indications for a charge neutral substitution reaction of adsorbed anions by hydroxide, which would not show up in cyclic voltammetry. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Molecular self assembly and chiral recognition of copper octacyanophthalocyanine on Au(111): Interplay of intermolecular and molecule-substrate interactions.

    Sk, Rejaul; Dhara, Barun; Miller, Joel; Deshpande, Aparna

    Submolecular resolution scanning tunneling microscopy (STM) of copper octacyanophthalocyanine, CuPc(CN)8, at 77 K demonstrates that these achiral molecules form a two dimensional (2D) tetramer-based self-assembly upon evaporation onto an atomically flat Au(111) substrate. They assemble in two different structurally chiral configurations upon adsorption on Au(111). Scanning tunneling spectroscopy (STS),acquired at 77 K, unveils the HOMO and LUMO energy levels of this self-assembly. Voltage dependent STM images show that each molecule in both the structurally chiral configurations individually becomes chiral by breaking the mirror symmetry due to the enhanced intermolecular dipolar coupling interaction at the LUMO energy while the individual molecules remain achiral at the HOMO energy and within the HOMO-LUMO gap. At the LUMO energy, the handedness of the each chiral molecule is decided by the direction of the dipolar coupling interaction in the tetramer unit cell. This preference for LUMO energy indicates that this chirality is purely electronic in nature and it manifests on top of the organizational chirality that is present in the self-assembly independent of the orbital energy. Supported by IISER Pune and DAE-BRNS, India (Project No. 2011/20/37C/17/BRNS).

  7. Study of Alkylthiolate Self-assembled Monolayers on Au(111) Using a Semilocal meta-GGA Density Functional

    Ferrighi, Lara; Pan, Yun-xiang; Grönbeck, Henrik

    2012-01-01

    We present a density functional theory study of the structure and stability of self-assembled monolayers (SAMs) of alkylthiolate on Au(111) as a function of the alkyl chain length. The most favorable structure of the SAMs involves an RS–Au–SR complex (S being sulfur, R being an alkyl chain) forme....... In particular, the use of M06-L yields an increased stability of the SAMs with increasing alkyl chain length and an increased attractive interaction between RS–Au–SR complexes at shorter distances....... through sandwiching one Au adatom by two alkylthiolates (RSs). Comparing a generalized gradient (GGA-PBE) and a meta-GGA (MGGA-M06-L) exchange-correlation functional we find that only the meta-GGA functional predicts the experimentally observed attractive intermolecular interactions within the SAMs...

  8. Gold Mining by Alkanethiol Radicals: Vacancies and Pits in the Self-Assembled Monolayers of 1-Propanethiol and 1-Butanethiol on Au(111)

    Wang, Yun; Chi, Qijin; Hush, Noel S.

    2011-01-01

    Scanning-tunneling microscopy (STM) under electrochemical control (in situ STM) in aqueous solution, combined with a priori density functional theory (DFT) image simulations at room temperature, reveals the atomic nature of the interface between Au(111) and self-assembled monolayers (SAMs) of 1-p...

  9. Scanning tunnelling microscopy of a foldamer prototype at the liquid/solid interface : water/Au(111) versus 1-octanol/graphite

    Klymchenko, Andrey S.; Schuurmans, Norbert; van der Auweraer, Mark; Feringa, Ben L.; van Esch, Jan; De Feyter, Steven

    2006-01-01

    We report the design and synthesis of a catechol based foldamer containing amide functionalized alkyl chains, and its monolayer formation at the liquid/solid interface. By scanning tunnelling microscopy, both at the 1-octanol/graphite interface as well as at the water/Au( 111) interface, the

  10. Dynamics of ordered-domain formation of DNA fragments on Au(111) with molecular resolution

    Wackerbarth, Hainer; Ulstrup, Jens

    2004-01-01

    KeyWords Plus: SCANNING-TUNNELING-MICROSCOPY; PSEUDOMONAS-AERUGINOSA AZURIN; INTERFACIAL ELECTRON-TRANSFER; SELF-ASSEMBLED MONOLAYERS; SINGLE-CRYSTAL; THIN-FILMS; SURFACES; ELECTROCHEMISTRY; VOLTAMMETRY; ADSORPTION......KeyWords Plus: SCANNING-TUNNELING-MICROSCOPY; PSEUDOMONAS-AERUGINOSA AZURIN; INTERFACIAL ELECTRON-TRANSFER; SELF-ASSEMBLED MONOLAYERS; SINGLE-CRYSTAL; THIN-FILMS; SURFACES; ELECTROCHEMISTRY; VOLTAMMETRY; ADSORPTION...

  11. Calculation of Quasi-Particle Energies of Aromatic Self-Assembled Monolayers on Au(111).

    Li, Yan; Lu, Deyu; Galli, Giulia

    2009-04-14

    We present many-body perturbation theory calculations of the electronic properties of phenylene diisocyanide self-assembled monolayers (SAMs) on a gold surface. Using structural models obtained within density functional theory (DFT), we have investigated how the SAM molecular energies are modified by self-energy corrections and how they are affected by the presence of the surface. We have employed a combination of GW (G = Green's function; W = screened Coulomb interaction) calculations of the SAM quasi-particle energies and a semiclassical image potential model to account for surface polarization effects. We find that it is essential to include both quasi-particle corrections and surface screening in order to provide a reasonable estimate of the energy level alignment at a SAM-metal interface. In particular, our results show that within the GW approximation the energy distance between phenylene diisocyanide SAM energy levels and the gold surface Fermi level is much larger than that found within DFT, e.g., more than double in the case of low packing densities of the SAM.

  12. Study of the helium cross-section of unsymmetric disulfide self-assembled monolayers on Au(111)

    Albayrak, Erol [Department of Materials and Metallurgical Engineering, Ahi Evran University, Kırşehir 40000 (Turkey); Karabuga, Semistan [Department of Chemistry, Kahramanmaraş Sütçü İmam University, Kahramanmaraş 46030 (Turkey); Bracco, Gianangelo [CNR-IMEM and Department of Physics, University of Genoa, Via Dodecaneso 33, Genoa 16146 (Italy); Danışman, M. Fatih, E-mail: danisman@metu.edu.tr [Department of Chemistry, Middle East Technical University, Ankara 06800 (Turkey)

    2016-12-30

    Highlights: • Unsymmetrtic disulfide (HDD and HOD) self assembled monolayers were grown on Au(111) by supersonic molecular beam deposition. • Helium scattering cross sections for these two different unsymmetric disulfides were determined. • A common low temperature film phase was observed for the studied disulfides. - Abstract: We have investigated the formation of self-assembled monolayers (SAMs) of 11-hydroxyundecyl decyl disulfide (CH{sub 3}-(CH{sub 2}){sub 9}-S-S-(CH{sub 2}){sub 11}-OH, HDD) and 11-hydroxyundecyl octadecyl disulfide (CH{sub 3}-(CH{sub 2}){sub 17}-S-S-(CH{sub 2}){sub 11}-OH, HOD) produced by supersonic molecular beam deposition (SMBD). The study has been carried out by means of helium diffraction at very low film coverage. In this regime helium single molecule cross sections have been estimated in a temperature range between 100 K and 450 K. The results show a different behavior above 300 K that has been interpreted as the starting of mobility with the formation of two thiolate moieties either linked by a gold adatom or distant enough to prevent cross section overlapping. Finally, helium diffraction patterns measured at 80 K for the SAMs grown at 200 K are discussed and the results support the proposed hypothesis of molecular dissociation based on the cross section data.

  13. Reversible switching in self-assembled monolayers of azobenzene thiolates on Au (111) probed by threshold photoemission

    Heinemann, Nils, E-mail: heinemann@physik.uni-kiel.de [Institut fuer Experimentelle und Angewandte Physik, Christian-Albrechts-Universitaet zu Kiel, Leibnizstr. 19, 24098 Kiel (Germany); Grunau, Jan; Leissner, Till; Andreyev, Oleksiy; Kuhn, Sonja; Jung, Ulrich [Institut fuer Experimentelle und Angewandte Physik, Christian-Albrechts-Universitaet zu Kiel, Leibnizstr. 19, 24098 Kiel (Germany); Zargarani, Dordaneh; Herges, Rainer [Otto-Diels-Institut fuer Organische Chemie, Christian-Albrechts-Universitaet zu Kiel, Otto-Hahn-Platz 4, 24098 Kiel (Germany); Magnussen, Olaf; Bauer, Michael [Institut fuer Experimentelle und Angewandte Physik, Christian-Albrechts-Universitaet zu Kiel, Leibnizstr. 19, 24098 Kiel (Germany)

    2012-06-19

    Highlights: Black-Right-Pointing-Pointer Photoelectron spectroscopy of liquid phase prepared SAMs of azobenzene derivative. Black-Right-Pointing-Pointer Photo-induced reversible switching in densely packed SAM is monitored. Black-Right-Pointing-Pointer Maximum density of switched molecules in SAM is derived from photoemission data. Black-Right-Pointing-Pointer Switching reaction only enabled at defects sites within the molecular layer. - Abstract: The reversible photo- and thermally activated isomerization of the molecular switch 3-(4-(4-Hexyl-phenylazo)-phenoxy)-propane-1-thiol (ABT, short for AzoBenzeneThiol) deposited by self-assembly from solution on Au (111) was studied using laser-based photoelectron spectroscopy. Differences in the molecular dipole moment characteristic for the trans and the cis isomer of ABT were monitored via changes in the sample work function, accessible by detection of the threshold energy for photoemission. A quantitative analysis of our data shows that the fraction of molecules within the densely packed monolayer that undergoes a switching process is of the order of 1%. This result indicates the relevance of substrate and film defects required to overcome the steric or electronic hindrance of the isomerization reaction in a densely packed monolayer.

  14. Chemically Transformable Configurations of Mercaptohexadecanoic Acid Self-Assembled Monolayers Adsorbed on Au(111)

    van Buuren, T; Bostedt, C; Nelson, A J; Terminello, L J; Vance, A L; Fadley, C S; Willey, T M

    2003-01-01

    Carboxyl terminated Self-Assembled Monolayers (SAMs) are commonly used in a variety of applications, with the assumption that the molecules form well ordered monolayers. In this work, NEXAFS verifies well ordered monolayers can be formed using acetic acid in the solvent. Disordered monolayers with unbound molecules present in the result using only ethanol. A stark reorientation occurs upon deprotonation of the endgroup by rinsing in a KOH solution. This reorientation of the endgroup is reversible with tilted over, hydrogen bound carboxyl groups while carboxylate-ion endgroups are upright. C1s photoemission shows that SAMs formed and rinsed with acetic acid in ethanol, the endgroups are protonated, while without, a large fraction of the molecules on the surface are carboxylate terminated

  15. Addresses

    Town of Chapel Hill, North Carolina — Point features representing locations of all street addresses in Orange County, NC including Chapel Hill, NC. Data maintained by Orange County, the Town of Chapel...

  16. Approach to Interfacial and Intramolecular Electron Transfer of the Diheme Protein Cytochrome c(4) Assembled on Au(111) Surfaces

    Chi, Qijin; Zhang, Jingdong; Taner, Arslan

    2010-01-01

    in homogeneous solution for which kinetic analysis clearly testifies to electrostatic cooperative effects but no intramolecular, interheme ET higher than 0.1-10 s(-1). This difference suggests a strong gating feature of the process. On the basis of the three-dimensional structure of P. stutzeri cyt c(4), gating...

  17. Surface polymerization of (3,4-ethylenedioxythiophene) probed by in situ scanning tunneling microscopy on Au(111) in ionic liquids.

    Ahmad, Shahzada; Carstens, Timo; Berger, Rüdiger; Butt, Hans-Jürgen; Endres, Frank

    2011-01-01

    The electropolymerization of 3,4-ethylenedioxythiophene (EDOT) to poly(3,4-ethylenedioxythiophene) (PEDOT) was investigated in the air and water-stable ionic liquids 1-hexyl-3-methylimidazolium tris(pentafluoroethyl) trifluorophosphate [HMIm]FAP and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) amide [EMIm]TFSA. In situ scanning tunnelling microscopy (STM) results show that the electropolymerization of EDOT in the ionic liquid can be probed on the nanoscale. In contrast to present understanding, it was observed that the EDOT can be oxidised in ionic liquids well below its oxidation potential and the under potential growth of polymer was visualized by in situ STM. These results serve as the first study to confirm the under potential growth of conducting polymers in ionic liquids. Furthermore, ex situ microscopy measurements were performed. Quite a high current of 670 nA was observed on the nanoscale by conductive scanning force microscopy (CSFM).

  18. Direct patterning of negative nanostructures on self-assembled monolayers of 16-mercaptohexadecanoic acid on Au(111) substrate via dip-pen nanolithography

    Zheng Zhikun; Yang Menglong; Liu Yaqing; Zhang Bailin

    2006-01-01

    Both bare and self-assembled monolayer (SAM) protected gold substrate could be etched by allyl bromide according to atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS) and inductively coupled plasma mass spectrometric (ICPMS) analysis results. With this allyl bromide ink material, negative nanopatterns could be fabricated directly by dip-pen nanolithography (DPN) on SAMs of 16-mercaptohexadecanoic acid (MHA) on Au(111) substrate. A tip-promoted etching mechanism was proposed where the gold-reactive ink could penetrate the MHA resist film through tip-induced defects resulting in local corrosive removal of the gold substrate. The fabrication mechanism was also confirmed by electrochemical characterization, energy dispersive spectroscopy (EDS) analysis and fabrication of positive nanopatterns via a used DPN tip

  19. Direct patterning of negative nanostructures on self-assembled monolayers of 16-mercaptohexadecanoic acid on Au(111) substrate via dip-pen nanolithography

    Zheng, Zhikun; Yang, Menglong; Liu, Yaqing; Zhang, Bailin

    2006-11-01

    Both bare and self-assembled monolayer (SAM) protected gold substrate could be etched by allyl bromide according to atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS) and inductively coupled plasma mass spectrometric (ICPMS) analysis results. With this allyl bromide ink material, negative nanopatterns could be fabricated directly by dip-pen nanolithography (DPN) on SAMs of 16-mercaptohexadecanoic acid (MHA) on Au(111) substrate. A tip-promoted etching mechanism was proposed where the gold-reactive ink could penetrate the MHA resist film through tip-induced defects resulting in local corrosive removal of the gold substrate. The fabrication mechanism was also confirmed by electrochemical characterization, energy dispersive spectroscopy (EDS) analysis and fabrication of positive nanopatterns via a used DPN tip.

  20. Thermovoltage in scanning tunnelling microscopy. Study of heterogeneous metal surfaces on atomic scale; Thermospannung in der Rastertunnelmikroskopie. Untersuchung heterogener Metalloberflaechen auf atomarer Skala

    Weyers, B.

    2005-07-01

    In this thesis the thermovoltage has been studied via a tunnel barrier under different aspects. Au(111) has been chosen as substrate. The mean free path of the electrons on the Au(111) surface was determined by a comparison of the standing waves on stage edges with the theoretical prediction. The measurements were performed at different temperatures. Detailed studies were performed on Au(111), Cu(111), and Cu(110) in order to examine the question whether the cause for strong signal on the stage edges lies in the surface state itself or in the band gap. The mani theme of this thesis is the study of a binary metal system, in this case silver on Au(111).

  1. Investigation of the deposition and thermal behavior of striped phases of unsymmetric disulfide self-assembled monolayers on Au(111): The case of 11-hydroxyundecyl decyl disulfide

    Albayrak, Erol [Department of Materials and Metallurgical Engineering, Ahi Evran University, Kırşehir 40000 (Turkey); Karabuga, Semistan [Department of Chemistry, Kahramanmaraş Sütçü İmam University, Kahramanmaraş 46030 (Turkey); Bracco, Gianangelo [CNR-IMEM and Department of Physics, University of Genoa, via Dodecaneso 33, Genoa 16146 (Italy); Danışman, M. Fatih, E-mail: danisman@metu.edu.tr [Department of Chemistry, Middle East Technical University, Ankara 06800 (Turkey)

    2015-01-07

    Self-assembled monolayers (SAMs) of unsymmetric disulfides on Au(111) are used to form mixed SAMs that can be utilized in many applications. Here, we have studied 11-hydroxyundecyl decyl disulfide (CH{sub 3}–(CH{sub 2}){sub 9}–S–S–(CH{sub 2}){sub 11}–OH, HDD) SAMs produced by supersonic molecular beam deposition and characterized by He diffraction. The film growth was monitored at different temperatures up to a coverage which corresponds to a full lying down phase and the diffraction analysis shows that below 250 K the phase is different from the phase measured above 300 K. During the annealing of the film, two phase transitions were observed, at 250 K and 350 K. The overall data suggest that the former is related to an irreversible phase separation of HDD above 250 K to decanethiolate (–S–(CH{sub 2}){sub 9}–CH{sub 3}, DTT) and hydroxyundecylthiolate (–S–(CH{sub 2}){sub 11}–OH, MUDT), while the latter to a reversible melting of the film. Above 450 K, the specular intensity shows an increase related to film desorption and different chemisorbed states were observed with energies in the same range as observed for decanethiol (H–S–(CH{sub 2}){sub 9}–CH{sub 3}, DT) and mercaptoundecanol (H–S–(CH{sub 2}){sub 11}–OH, MUD) SAMs.

  2. Catalytic monolayer voltammetry and in situ scanning tunneling microscopy of copper nitrite reductase on cysteamine-modified Au(111) electrodes

    Zhang, Jingdong; Welinder, A.C.; Hansen, Allan Glargaard

    2003-01-01

    electrochemical scanning tunneling microscopy (in situ STM) directly in aqueous acetate buffer, pH 6.0 has been used. High-resolution in situ STM shows that cysteamine packs into ordered domains with strip features of a periodic distance of 11.7 +/- 0.3 Angstrom. No voltammetric signals of the nitrite substrate...... on this surface could be detected. A strong cathodic catalytic wave appears in the presence of nitrite. The catalytic current follows a Michaelis-Menten pattern with a Michaelis constant of K-m approximate to 44 muM, which is close to the value for AxCuNiR in homogeneous solution. The apparent catalytic rate...

  3. Comparing Ullmann Coupling on Noble Metal Surfaces: On-Surface Polymerization of 1,3,6,8-Tetrabromopyrene on Cu(111) and Au(111)

    Pham, Tuan Anh; Song, Fei; Nguyen, Manh-Thuong

    2016-01-01

    to a dissociation of the C−Br bonds and the formation of disordered metal-coordinated molecular networks. Further annealing at 573 K resulted in the formation of covalently linked disordered networks. Importantly, we found that the chosen substrate not only plays an important role as catalyst for the Ullmann...

  4. Cysteine adsorption on the Au(111) surface and the electron transfer in configuration of a scanning tunneling microscope: A quantum-chemical approach

    Nazmutdinov, R.R.; Manyurov, I.R.; Zinkicheva, T.T.

    2007-01-01

    Adsorption of two forms, molecule and radical, of amino acid L-cysteine (Cys) on the Au-12 cluster that simulates the (111) face of single-crystal gold is studied in the framework of the density functional theory. Effects of solvation of adsorbed Cys particles and lateral interaction in a monolay...

  5. Voltammetry and Molecular Assembly of G-quadruplex DNAzyme on Single-crystal Au(111)-electrode Surfaces – Hemin as an Electrochemical Intercalator

    Zhang, Ling; Ulstrup, Jens; Zhang, Jingdong

    2016-01-01

    DNA quadruplexes (qs’s) are a class of “non-canonical” oligonucleotides (OGNs) composed of stacked guanine (G) quartets generally stabilized by monovalent cations. Metal porphyrins selectively bind to G-qs complexes to form DNAzyme, which can exhibit peroxidase and other catalytic activity simila...

  6. Surface chemistry of 2-butanol and furfural on Cu, Au and Cu/Au single crystals

    Megginson, Rory

    2016-01-01

    In this study, the adsorption of 2-butanol and furfural was investigated on Au (111), Cu (111) and Cu/Au (111) surfaces. It was hoped that by studying how these species adsorbed on these surfaces , insight would be provided into the roles of Cu and Au in the “hydrogen free” hydrogenation of furfural to furfuryl alcohol. This is a valuable process as currently furfuryl alcohol is derived from crude oil but it is possible to derive furfural from corn husk making it a greener process...

  7. Symposium Supramolecular Assemblies on Surface: Nanopatterning, Functionality and Reactivity

    2016-05-19

    formed and we relate these observations to recent reports of de- wetting of C60 on alkali halide surfaces. The hBN flakes, which are prepared by... annealing will be discussed while for dicarbonitrile polyphenyl derivatives the adsorption behavior on Au(111) will be compared to the one on graphene

  8. Adsorption of human insulin on single-crystal gold surfaces investigated by in situ scanning tunnelling microscopy and electrochemistry

    Welinder, Anna Christina; Zhang, Jingdong; Steensgaard, D.B.

    2010-01-01

    sweep, LSV, cyclic, CV, and square wave (SQWV) voltammetry. Multifarious electrochemical patterns were observed. Most attention was given to reductive desorption caused by insulin binding to the Au-surfaces via up to three disulfide groups per insulin monomer, presumably converted to single Au-S links....... SQWV suggested the Au-S bond strength order Au(111) > Au(110) > Au(100) based on the reductive desorption potentials. The voltammetric diversity was paralleled by different in situ STM insulin adsorption modes on the three surfaces. Single-molecule resolution was achieved in all cases. The coverage...... followed the order Au(110) > Au(100) > Au(111) and differs from the reductive desorption order that records the Au-S bonding element. Evenly distributed single molecules were scattered over large Au(111)-terraces, with intriguing molecular arrays disclosed near the terrace edges. In comparison, high...

  9. Planetary Atmosphere and Surfaces Chamber (PASC: A Platform to Address Various Challenges in Astrobiology

    Eva Mateo-Marti

    2014-08-01

    . Furthermore, the stability and presence of certain minerals on planetary surfaces and the potential habitability of microorganisms under various planetary environmental conditions can be studied using our apparatus. Therefore, these simulation chambers can address multiple different challenging and multidisciplinary astrobiological studies.

  10. Chemisorbed and physisorbed structures for 1,10-phenanthroline and dipyrido[3,2-a : 2 ',3 '-c]phenazine on au(111)

    Cafe, P.F.; Larsen, Allan G.; Yang, W.R.

    2007-01-01

    physisorbed structures are not pitted and fluctuate dynamically, involving aligned (4 x 4) surface domains with shortrange (ca. 20 molecules) order for PHEN but unaligned chains with medium-range (ca. 100 molecules) order for DPPZ. In contrast, the chemisorbed PHEN monolayers remain stable for days...... structures are optimized using plane-wave density-functional theory (DFT) calculations for the surface structure. Realistic binding energies are then obtained adding dispersive corrections determined using complete-active-space self-consistent field calculations using second-order perturbation theory (CASPT2......) applied to cluster-interaction models. A fine balance between the large adsorbate -adsorbate dispersive forces, adsorbate-surface dispersive forces, gold ligation energy, and surface mining energy is shown to dictate the observed phenomena, leading to high surface mobility and substrate/surface lattice...

  11. High-Resolution Scanning Tunneling Microscopy Studies of Molecular Nanostructures on Surfaces

    Song, Xin

    . First, to study the role of hydrogen bonding in self-assembly, we investigate the monomolecular self-assembled system of pyrene-4,5,9,10-tetrone and phenanthrene- 9,10-dione molecules on Au(111) and HOPG surface respectively and the binary molecular self-assembled system of stearic acid and guanine...

  12. On the influence of the aliphatic linker on fabrication of highly ordered and orientated self-assembled monolayers of aromatic selenols on AU(111)

    Azzam, Waleed; Al-Rawashdeh, Nathir A F; Al-Refaie, Najd; Shekhah, Osama; Bashir, Asif

    2014-01-01

    their adlayer SAM structure and surface morphology. The molecular adlayer structure and orientation of PMSe and BSe species were found to vary significantly with the immersion time (IT). The resulting PMSe films were poorly organized, and the structure

  13. Metalloprotein Adsorption on Au(111) and Polycrystalline Platinum Investigated by In Situ Scanning Tunnelling Microscopy with Molecular and Sub-Molecular Resolution

    Friis, Esben P.; Andersen, Jens Enevold Thaulov; Madsen, Lars Lithen

    1998-01-01

    Redox metalloproteins exhibit interesting features such as long-range electron transfer (ET), cooperative e€ects etc. of importance in relation to fundamental ET theory, and mapped in considerable detail. Adsorption and interfacial electrochemical ET of metalloproteins at metallic surfaces is also...... linking, facile ET routes through the protein, and tunnel enhancement by the low-lying redox level of the copper atom. The particular electronic-vibrational three-level con®guration in in situ STM of metalloproteins, ®nally, o€ers a new way of distinction between superexchange, coherent, and sequential ET...

  14. Electrochemical characterization of a 1,8-octanedithiol self-assembled monolayer (ODT-SAM) on a Au(111) single crystal electrode

    Garcia-Raya, Daniel; Madueno, Rafael; Sevilla, Jose Manuel; Blazquez, Manuel; Pineda, Teresa [Departamento de Quimica Fisica y Termodinamica Aplicada, Universidad de Cordoba, Campus de Rabanales, Cordoba (Spain)

    2008-11-15

    Recently, it has becoming increasingly important to control the organization of self-assembled monolayers (SAMs) of {omega}-functionalized thiols for its potential applications in the construction of more complex molecular architectures. In this paper, we report on the spontaneous formation of a SAM of octanedithiol (ODT) as a function of the modification time. Electrochemical techniques such as cyclic voltammetry, double layer capacitance and electrochemical impedance spectroscopy are used for the characterization of this monolayer. The increase in modification time brings about changes in the octanedithiol self-assembled monolayer (ODT-SAM) reductive desorption voltammograms that indicate an evolution toward a more ordered and compact monolayer. This trend has also been found by following the changes in the electron transfer processes of the redox probe K{sub 3}Fe(CN){sub 6}. In fact, the ODT-SAM formed at low-modification time does not significantly perturb the electrochemical response as it is typical of either a low coverage or of the presence of large defects in the layer. Upon increasing the modification time, the voltammograms of the redox probe adopt a sigmoidal shape indicating the existence of pinholes in the monolayer distributed as an array of microelectrodes. The surface coverage as well as the size and distribution of these pinholes have been determined by the impedance technique that gives a more reliable evaluation of these monolayer structural parameters. (author)

  15. Surface acidity scales: Experimental measurements of Brønsted acidities on anatase TiO2 and comparison with coinage metal surfaces

    Silbaugh, Trent L.; Boaventura, Jaime S.; Barteau, Mark A.

    2016-08-01

    The first quantitative surface acidity scale for Brønsted acids on a solid surface is presented through the use of titration-displacement and equilibrium experiments on anatase TiO2. Surface acidities of species on TiO2 correlated with gas phase acidities, as was previously observed in qualitative studies of Brønsted acid displacement on Ag(110), Cu(110) and Au(111). A 90% compression of the surface acidity scale relative to the gas phase was observed due to compensation from the covalent component of the conjugate base - surface bond. Adsorbed conjugate bases need not be completely anionic for correlations with gas phase acidities to hold. Positive and negative substituent effects, such as substituted fluorine and hydrocarbon sidechain dispersion interactions with the surface, may modify the surface acidity scale, in agreement with previous experimental and theoretical work on Au(111).

  16. Selection of conformational states in surface self-assembly for a molecule with eight possible pairs of surface enantiomers

    Nuermaimaiti, Ajiguli; Schultz-Falk, Vickie; Lind Cramer, Jacob

    2016-01-01

    Self-assembly of a molecule with many distinct conformational states, resulting in eight possible pairs of surface enantiomers, is investigated on a Au(111) surface under UHV conditions. The complex molecule is equipped with alkyl and carboxyl moieties to promote controlled self-assembly of lamel......Self-assembly of a molecule with many distinct conformational states, resulting in eight possible pairs of surface enantiomers, is investigated on a Au(111) surface under UHV conditions. The complex molecule is equipped with alkyl and carboxyl moieties to promote controlled self......-assembly of lamellae structures. From statistical analysis of Scanning Tunnelling Microscopy (STM) data we observe a clear selection of specific conformational states after self-assembly. Using Density Functional Theory (DFT) calculations we rationalise how this selection is correlated to the orientation of the alkyl...

  17. High-temperature morphology of stepped gold surfaces

    Bilalbegovic, G.; Tosatti, E.; Ercolessi, F.

    1992-04-01

    Molecular dynamics simulations with a classical many-body potential are used to study the high-temperature stability of stepped non-melting metal surfaces. We have studied in particular the Au(111) vicinal surfaces in the (M+1, M-1, M) family and the Au(100) vicinals in the (M, 1, 1) family. Some vicinal orientations close to the non-melting Au(111) surface become unstable close to the bulk melting temperature and facet into a mixture of crystalline (111) regions and localized surface-melted regions. On the contrary, we do not find high-temperature faceting for vicinals close to Au(100), also a non-melting surface. These (100) vicinal surfaces gradually disorder with disappearance of individual steps well below the bulk melting temperature. We have also studied the high-temperature stability of ledges formed by pairs of monoatomic steps of opposite sign on the Au(111) surface. It is found that these ledges attract each other, so that several of them merge into one larger ledge, whose edge steps then act as a nucleation site for surface melting. (author). 43 refs, 8 figs

  18. Observation of the adsorption and desorption of vibrationally excited molecules on a metal surface

    Shirhatti, Pranav R.; Rahinov, Igor; Golibrzuch, Kai; Werdecker, Jörn; Geweke, Jan; Altschäffel, Jan; Kumar, Sumit; Auerbach, Daniel J.; Bartels, Christof; Wodtke, Alec M.

    2018-06-01

    The most common mechanism of catalytic surface chemistry is that of Langmuir and Hinshelwood (LH). In the LH mechanism, reactants adsorb, become thermalized with the surface, and subsequently react. The measured vibrational (relaxation) lifetimes of molecules adsorbed at metal surfaces are in the range of a few picoseconds. As a consequence, vibrational promotion of LH chemistry is rarely observed, with the exception of LH reactions occurring via a molecular physisorbed intermediate. Here, we directly detect adsorption and subsequent desorption of vibrationally excited CO molecules from a Au(111) surface. Our results show that CO (v = 1) survives on a Au(111) surface for 1 × 10-10 s. Such long vibrational lifetimes for adsorbates on metal surfaces are unexpected and pose an interesting challenge to the current understanding of vibrational energy dissipation on metal surfaces. They also suggest that vibrational promotion of surface chemistry might be more common than is generally believed.

  19. Electrochemical Properties of Alkanethiol Monolayers Adsorbed on Nanoporous Au Surfaces

    Chu, Yeon Yi; Seo, Bora; Kim, Jong Won

    2010-01-01

    We investigated the electrochemical properties of alkanethiol monolayers adsorbed on NPG surfaces by cyclic voltammetry and electrochemical impedance spectroscopy, and the results are compared to those on flat Au surfaces. The reductive desorption of alkanethiols on NPG surfaces is observed in more negative potential regions than that on flat Au surfaces due the stronger S-Au interaction on NPG surfaces. While the electron transfer through alkanethiol monolayers on flat Au surfaces occurs via a tunneling process through the monolayer films, the redox species can permeate through the monolayers on NPG surfaces to transfer the electrons to the Au surfaces. The results presented here will help to elucidate the intrinsic electrochemical properties of alkanethiol monolayers adsorbed on curved Au surfaces, particularly on the surface of AuNPs. Self-assembled monolayers (SAMs) of thiolate molecules on Au surfaces have been the subject of intensive research for the last few decades due to their unique physical and chemical properties. The well-organized surface structures of thiolate SAMs with various end-group functionalities can be further utilized for many applications in biology and nanotechnology. In addition to the practical applications, SAMs of thiolate molecules on Au surfaces also provide unique opportunities to address fundamental issues in surface chemistry such as self-organized surface structures, electron transfer behaviors, and moleculesubstrate interactions. Although there have been numerous reports on the fundamental physical and chemical properties of thiolate SAMs on Au surfaces, most of them were investigated on flat Au surfaces, typically on well-defined Au(111) surfaces

  20. Adsorption of 5-halouracils on Au(111)

    Plekan, O.; Feyer, V.; Tsud, N.; Vondráček, Martin; Cháb, Vladimír; Matolín, V.; Prince, K. C.

    2012-01-01

    Roč. 606, 3-4 (2012), s. 435-443 ISSN 0039-6028 R&D Projects: GA MŠk(CZ) LC06058 Institutional support: RVO:68378271 Keywords : 5-halouracils * gold * chemisorption * XPS * NEXAFS Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.838, year: 2012

  1. Surface plasmon resonance spectroscopic study of UV-addressable phenylalanine sensing based on a self-assembled spirooxazine derivative monolayer

    Suk, Shinae; Suh, Hee-Jung; Gun An, Won; Kim, Jae-Ho; Jin, Sung-Ho; Kim, Sung-Hoon; Gal, Yeong-Soon; Koh, Kwangnak

    2004-01-01

    Light-addressable compounds are very interesting due to the possibilities of their practical use such as optical switches and memories or variable transmission materials. For example, transportation of phenylalanine across liposomal bilayers mediated by a photoresponsive carrier like spirooxazine through electrostatic interaction between phenylalanine and spirooxazine derivative. Thus, the spirooxazine is expected to form a UV-addressable phenylalanine sensing interface. In this study, we prepared phenylalanine sensing interface of a spirooxazine derivative by self-assembly technique and evaluated interaction between a spirooxazine moiety and phenylalanine with a surface plasmon resonance (SPR). The refractive index change of monolayer caused by interaction between a spirooxazine derivative and phenylalanine led to the SPR angle shifts upon UV irradiation. The SPR angle shift increased with increasing the concentration of phenylalanine solution. These results indicated that the spirooxazine derivative self-assembled monolayer (SAM) has an application potential for UV-addressable phenylalanine sensing

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

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

    2017-01-01

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

  3. Dynamics of Pseudomonas aeruginosa azurin and its Cys3Ser mutant at single crystal gold surfaces investigated by cyclic voltammetry and atomic force microscopy

    Friis, Esben P.; Andersen, Jens Enevold Thaulov; Madsen, Lars Lithen

    1997-01-01

    Cyclic voltammetry of Pseudomonas aeruginosa azurin on polycrystalline gold is reversible (E0=360mV vs she;50mM ammonium acetate) but the voltammetric signals decay with time constants of about 3x10-3 s-1. No signal is observed for monocrystalline Au(111). Cys3Ser azurin is electrochemically inac...... into the solution, recovering the free Au(111) surface. The cyclic voltammetry and AFM data are consistent with time dependent adsorption of the azurins on gold via the disulphide bridge (wild-type) or free thiol group (Cys3Ser mutant).......Cyclic voltammetry of Pseudomonas aeruginosa azurin on polycrystalline gold is reversible (E0=360mV vs she;50mM ammonium acetate) but the voltammetric signals decay with time constants of about 3x10-3 s-1. No signal is observed for monocrystalline Au(111). Cys3Ser azurin is electrochemically...... inactive on either type of gold electrode but shows a reversible although decaying peak (362mV, 50mM ammonium acetate; decay time constant ~ 2x10-3 s-1) on edge-plane pyrolytic graphite.Ex situ and in situ atomic force microscopy (AFM) of the azurins on Au(111) show initially arrays of protein structures...

  4. Potential dependent adhesion forces on bare and underpotential deposition modified electrode surfaces

    Serafin, J.M.; Hsieh, S.J.; Monahan, J.; Gewirth, A.A. [Univ. of Illinois, Urbana, IL (United States)

    1998-12-03

    Adhesion force measurements are used to determine the potential dependence of the force of adhesion between a Si{sub 3}N{sub 4} cantilever and a Au(111) surface modified by the underpotential deposition (upd) of Bi or Cu in acid solution or by oxide formation. The measured work of adhesion is near zero for most of the potential region examined in Bi upd but rises after the formation of a full Bi monolayer. The work of adhesion is high at positive potentials for Cu upd but then decreases as the Cu partial and full monolayers are formed. The work of adhesion is low in the oxide region on Au(111) but rises following the sulfate disordering transition at 1.1 V vs NHE. These results are interpreted in terms of the degree of solvent order on the electrode surface.

  5. High-resolution He beam scattering as a tool for the investigation of the structural and dynamical properties of surface soliton dislocations

    El-Batanouny, M.; Martini, K.M.

    1986-01-01

    We discuss the applicability of high-resolution-He-beam/surface scattering to the investigation of the structural and dynamic properties of soliton-like surface misfit dislocations and associated phase transitions. We present evidence, based on recent He diffraction measurements, for the existence of double-sine-Gordon soliton-like dislocations on the reconstructed Au(111) surface. 18 refs., 3 figs., 1 tab

  6. N-Heterocyclic carbenes on close-packed coinage metal surfaces: bis-carbene metal adatom bonding scheme of monolayer films on Au, Ag and Cu.

    Jiang, Li; Zhang, Bodong; Médard, Guillaume; Seitsonen, Ari Paavo; Haag, Felix; Allegretti, Francesco; Reichert, Joachim; Kuster, Bernhard; Barth, Johannes V; Papageorgiou, Anthoula C

    2017-12-01

    By means of scanning tunnelling microscopy (STM), complementary density functional theory (DFT) and X-ray photoelectron spectroscopy (XPS) we investigate the binding and self-assembly of a saturated molecular layer of model N -heterocyclic carbene (NHC) on Cu(111), Ag(111) and Au(111) surfaces under ultra-high vacuum (UHV) conditions. XPS reveals that at room temperature, coverages up to a monolayer exist, with the molecules engaged in metal carbene bonds. On all three surfaces, we resolve similar arrangements, which can be interpreted only in terms of mononuclear M(NHC) 2 (M = Cu, Ag, Au) complexes, reminiscent of the paired bonding of thiols to surface gold adatoms. Theoretical investigations for the case of Au unravel the charge distribution of a Au(111) surface covered by Au(NHC) 2 and reveal that this is the energetically preferential adsorption configuration.

  7. Surface assisted oxidation of flat lying organic molecules - a real-time STM study

    Waldmann, Thomas; Roos, Michael; Breitruck, Achim; Hoster, Harry E.; Behm, R. Juergen [Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm (Germany); Kuenzel, Daniela; Gross, Axel [Institute of Theoretical Chemistry, Ulm University, D-89069 Ulm (Germany)

    2010-07-01

    Using time resolved scanning tunneling microscopy (STM), we tested the interaction of O{sub 2} from gas-phase with ordered adlayers of the Bis(terpyridine) derivative 2,4'-BTP on Au(111), Ag(111) and graphite (HOPG) surfaces at T = 300 K. At an O{sub 2} pressure of 10{sup -5} mbar, the adlayers on Ag(111) undergo chemical and structural changes. These include modifications of the 2-pyridyl rings of individual 2,4'-BTP adsorbates and rearrangements of the hydrogen bonded adlayer. Since we do not observe similar changes on HOPG and Au(111), we assume that Ag(111) acts as catalyst for the underlying processes. Based on our STM data in combination with DFT calculations, we conclude that the observed reaction is pyridyl-N-oxide formation. Furthermore, we derive reaction yields, enantiomeric excess, reaction rates and reaction orders from the time-resolved STM data.

  8. Predicting supramolecular self-assembly on reconstructed metal surfaces

    Roussel, Thomas J.; Barrena, Esther; Ocal, Carmen; Faraudo, Jordi

    2014-06-01

    The prediction of supramolecular self-assembly onto solid surfaces is still challenging in many situations of interest for nanoscience. In particular, no previous simulation approach has been capable to simulate large self-assembly patterns of organic molecules over reconstructed surfaces (which have periodicities over large distances) due to the large number of surface atoms and adsorbing molecules involved. Using a novel simulation technique, we report here large scale simulations of the self-assembly patterns of an organic molecule (DIP) over different reconstructions of the Au(111) surface. We show that on particular reconstructions, the molecule-molecule interactions are enhanced in a way that long-range order is promoted. Also, the presence of a distortion in a reconstructed surface pattern not only induces the presence of long-range order but also is able to drive the organization of DIP into two coexisting homochiral domains, in quantitative agreement with STM experiments. On the other hand, only short range order is obtained in other reconstructions of the Au(111) surface. The simulation strategy opens interesting perspectives to tune the supramolecular structure by simulation design and surface engineering if choosing the right molecular building blocks and stabilising the chosen reconstruction pattern.The prediction of supramolecular self-assembly onto solid surfaces is still challenging in many situations of interest for nanoscience. In particular, no previous simulation approach has been capable to simulate large self-assembly patterns of organic molecules over reconstructed surfaces (which have periodicities over large distances) due to the large number of surface atoms and adsorbing molecules involved. Using a novel simulation technique, we report here large scale simulations of the self-assembly patterns of an organic molecule (DIP) over different reconstructions of the Au(111) surface. We show that on particular reconstructions, the molecule

  9. Reach Address Database (RAD)

    U.S. Environmental Protection Agency — The Reach Address Database (RAD) stores the reach address of each Water Program feature that has been linked to the underlying surface water features (streams,...

  10. One-pot reaction for the preparation of biofunctionalized self-assembled monolayers on gold surfaces

    Raigoza, Annette F.; Fies, Whitney; Lim, Amber; Onyirioha, Kristeen; Webb, Lauren J., E-mail: lwebb@cm.utexas.edu

    2017-02-01

    Highlights: • One-pot synthesis of α-helical-terminated self-assembled monolayers on Au(111). • Synthesis of high density, structured, and covalently bound α-helices on Au(111). • Characterization by surface-averaged and single molecule techniques. • Peptide-terminated surfaces for fabrication of biomaterials and sensors. - Abstract: The Huisgen cycloaddition reaction (“click” chemistry) has been used extensively to functionalize surfaces with macromolecules in a straightforward manner. We have previously developed a procedure using the copper(I)-catalyzed click reaction to tether synthetic α-helical peptides carrying two alkyne groups to a well-ordered azide-terminated alkanethiol self-assembled monolayer (SAM) on a Au(111) surface. While convenient, click-based strategies potentially pose significant problems from reagents, solvents, and reaction temperatures that may irreversibly damage some molecules or substrates. Tuning click chemistry conditions would allow individual optimization of reaction conditions for a wide variety of biomolecules and substrate materials. Here, we explore the utility of simultaneous SAM formation and peptide-attachment chemistry in a one-pot reaction. We demonstrate that a formerly multistep reaction can be successfully carried out concurrently by mixing azide-terminated alkanethiols, CuCl, and a propargylglycine-containing peptide over a bare gold surface in ethanol and reacting at 70 °C. X-ray photoelectron spectroscopy (XPS), surface infrared spectroscopy, surface circular dichroic (CD) spectroscopy, and scanning tunneling microscopy (STM) were used to determine that this one-pot reaction strategy resulted in a high density of surface-bound α-helices without aggregation. This work demonstrates the simplicity and versatility of a SAM-plus-click chemistry strategy for functionalizing Au surfaces with structured biomolecules.

  11. Voltammetry and in situ scanning tunnelling spectroscopy of osmium, iron, and ruthenium complexes of 2,2′:6′,2′′-terpyridine covalently linked to Au(111)-electrodes

    Salvatore, Princia; Hansen, Allan Glargaard; Moth-Poulsen, Kasper

    2011-01-01

    prepared in situ by first linking the terpy ligand to the surface via the S-atom, followed by addition of suitable metal compounds. The metal-terpy SAMs were studied by cyclic voltammetry (CV), and in situ scanning tunnelling microscopy with full electrochemical potential control of substrate and tip (in...

  12. Surface adhesion and confinement variation of Staphylococcus aurius on SAM surfaces

    Amroski, Alicia; Olsen, Morgan; Calabrese, Joseph; Senevirathne, Reshani; Senevirathne, Indrajith

    2012-02-01

    Controlled surface adhesion of non - pathogenic gram positive strain, Staphylococcus aureus is interesting as a model system due to possible development of respective biosensors for prevention and detection of the pathogenic strain methicillin resistant Staphylococcus aureus (MRSA) and further as a study for bio-machine interfacing. Self Assembled Monolayers (SAM) with engineered surfaces of linear thiols on Au(111) were used as the substrate. Sub cultured S. aureus were used for the analysis. The SAM layered surfaces were dipped in 2 -- 4 Log/ml S. aureus solution. Subsequent surface adhesion at different bacterial dilutions on surfaces will be discussed, and correlated with quantitative and qualitative adhesion properties of bacteria on the engineered SAM surfaces. The bacteria adhered SAM surfaces were investigated using intermittent contact, noncontact, lateral force and contact modes of Atomic Force Microscopy (AFM).

  13. The Use of Numerical Modeling to Address Surface and Subsurface Water Contamination due to Fracwater Spills in Larry's Creek, Pennsylvania

    Simon, C. A.; Arjmand, S.; Abad, J. D.

    2012-12-01

    Because of its relatively low carbon dioxide emissions, natural gas is considered to be more efficient and environmentally friendly than other non-renewable fuels. As a result of this, among other factors, in recent years natural gas has become one of the world's primary energy sources. In the United States, drilling to extract natural gas has substantially increased over the past few years. In the Marcellus Shale, unconventional gas is currently extracted by using two new techniques: horizontal drilling and hydraulic fracturing. Today, fracking fluids which have been applied as part of the hydraulic fracturing process to fracture the shale rock and release the gas, pose a major environmental concern. These fluids are highly contaminated with radionuclides and toxic metals and any exposure of this highly polluted water to surface water or soil could heavily contaminate the media. The area selected for the current study is the Larry's Creek, located in Lycoming County in Pennsylvania. Larry's Creek Watershed was adversely affected by coal and iron mines activities in the 19th century. Though, the water quality in this creek was considered to be good as of 2006. Recently, oil and gas drilling activities have raised concerns about the creek's water quality again. A major environmental hazard is the freshwater contamination by frac/flowback water. Drilling companies are using impoundments on site to keep fracwater, and to store and evaporate flowback water. However, these ponds may fail or leak due to construction problems and/or accidents. Close to Saladasburg, Larry's Creek's stream was observed running rich with clay in October 19, 2011. Historical measurements show very high turbidity during this period which has raised questions about water contamination by the gas industry activities in the upper stream of the watershed. An interstate watershed agency has reported spills in Wolf Run in different drilling sites in the Larry's Creek basin. The focus of this study

  14. Electronic properties and assambly of DNA-based molecules on gold surfaces

    Salvatore, Princia

    , highly base specific voltammetric peak in the presence of spermidine ions. A capacitive origin was attributed to this peak, and a novel route to detection of hybridization and base pair mismatches proposed on the basis of the high sensitivity to base pair mismatches showed by such ON-based monolayers...... as widely employed as Au(111) surfaces). In particular, SERS offered a valuable and rapid way ofcharacterising interactions between the DNA-based molecules and the NP surface, with no need for complex sample preparation....

  15. Unraveling surface enabled magnetic phenomena in low dimensional systems

    Baljozovic, Milos; Girovsky, Jan; Nowakowski, Jan; Ali, Md Ehesan; Rossmann, Harald; Nijs, Thomas; Aeby, Elise; Nowakowska, Sylwia; Siewert, Dorota; Srivastava, Gitika; WäCkerlin, Christian; Dreiser, Jan; Decurtins, Silvio; Liu, Shi-Xia; Oppeneer, Peter M.; Jung, Thomas A.; Ballav, Nirmalya

    Molecular spin systems with controllable interactions are of both fundamental and applied importance. These systems help us to better understand the fundamental origins of the interactions involved in low dimensional magnetic systems and to put them in the framework of existing models towards their further development. Following our first observation of exchange induced magnetic ordering in paramagnetic porphyrins adsorbed on ferromagnetic Co surface we showed that magnetic properties of such molecules can be controllably altered upon exposure to chemical and physical stimuli. In our most recent work it was shown that a synthetically programmed co-assembly of Fe and Mn phthalocyanines can also be realized on diamagnetic Au(111) surfaces where it induces long-range 2D ferrimagnetic order, at first glance in conflict with the Mermin-Wagner theory. Here we provide evidence for the first direct observation of such ordering from STM/STS and XMCD data and from DFT +U calculations demonstrating key role of the Au(111) surface states in mediating AFM RKKY coupling of the Kondo underscreened magnetic moments.

  16. Convocation address.

    Swaminathan, M S

    1998-07-01

    This address delivered to the 40th convocation of the International Institute for Population Sciences in India in 1998 opens by noting that a shortage of jobs for youth is India's most urgent problem but that the problems that attend the increasing numbers of elderly also require serious attention. The address then notes that the Earth's population is growing at an unsustainable rate while economic inequities among countries are increasing, so that, while intellectual property is becoming the most important asset in developed countries, nutritional anemia among pregnant women causes their offspring to be unable to achieve their full intellectual potential from birth. Next, the address uses a discussion of the 18th-century work on population of the Marquis de Condorcet and of Thomas Malthus to lead into a consideration of estimated increased needs of countries like India and China to import food grains in the near future. Next, the progress of demographic transition in Indian states is covered and applied to Mahbub ul Haq's measure of human deprivation developed for and applied to the region of the South Asian Association for Regional Cooperation (India, Pakistan, Bangladesh, Nepal, Sri Lanka, Bhutan, and the Maldives). The address continues by reiterating some of the major recommendations forwarded by a government of India committee charged in 1995 with drafting a national population policy. Finally, the address suggests specific actions that could be important components of the Hunger-Free India Programme and concludes that all success rests on the successful implementation of appropriate population policies.

  17. inaugral address

    While political reorientation and economic redress were of immediate concern, ... South African context, where widespread changes have been proposed for education at all ... education at school and other levels and needs to be addressed so as to ..... the major national curriculum intervention in environmental education.

  18. Convergent fabrication of a nanoporous two-dimensional carbon network from an aldol condensation on metal surfaces

    Landers, John; De Santis, Maurizio; Bendiab, Nedjma; Magaud, Laurence; Coraux, Johann; Chérioux, Frédéric; Lamare, Simon

    2014-01-01

    We report a convergent surface polymerization reaction scheme on Au(111), based on a triple aldol condensation, yielding a carbon-rich, covalent nanoporous two-dimensional network. The reaction is not self-poisoning and proceeds up to a full surface coverage. The deposited precursor molecules 1, 3, 5-tri(4’-acetylphenyl) first form supramolecular assemblies that are converted to the porous covalent network upon heating. The formation and structure of the network and of the intermediate steps are studied with scanning tunneling microscopy, Raman spectroscopy and density functional theory. (paper)

  19. Opening address

    Ianko, L.

    1993-01-01

    This short talk was the opening remarks to the attendees at this conference, presented by the Scientific Secretary, IWG-LMNPP, of the IAEA. This meeting is an effort to aid research on problems related to the general area of nuclear plant aging and life management. In particular it addresses fracture properties of reactor materials and components, both as installed, and at end of service condition. A major concern is relating measurements made on laboratory samples to properties displayed by actual reactor components

  20. Convocation address.

    Zakaria, R

    1996-07-01

    By means of this graduation address at the International Institute for Population Sciences (IIPS) in Bombay, the Chancellor of Urdu University voiced his concerns about overpopulation in India. During the speaker's tenure as Health Minister of Maharashtra, he implemented a sterilization incentive program that resulted in the state's having the best family planning (FP) statistics in India for almost 10 years. The incentive program, however, was misused by overenthusiastic officials in other states, with the result that the FP program was renamed the Family Welfare Programme. Population is growing in India because of improvements in health care, but the population education necessary to change fertility will require more time than the seriousness of the population problem allows. In the longterm, poverty and illiteracy must be addressed to control population. In the meanwhile, the graduate program at the IIPS should be expanded to include an undergraduate program, marriage age laws should be enforced, and misconceptions about religious objections to FP must be addressed. India can not afford to use the measures forwarded by developed countries to control population growth. India must integrate population control efforts with the provision of health care because if population continues to grow in the face of reduced infant mortality and longer life expectancy, future generations will be forced to live in a state of poverty and economic degradation.

  1. Tight control of light trapping in surface addressable photonic crystal membranes: application to spectrally and spatially selective optical devices (Conference Presentation)

    Letartre, Xavier; Blanchard, Cédric; Grillet, Christian; Jamois, Cécile; Leclercq, Jean-Louis; Viktorovitch, Pierre

    2016-04-01

    Surface addressable Photonic Crystal Membranes (PCM) are 1D or 2D photonic crystals formed in a slab waveguides where Bloch modes located above the light line are exploited. These modes are responsible for resonances in the reflection spectrum whose bandwidth can be adjusted at will. These resonances result from the coupling between a guided mode of the membrane and a free-space mode through the pattern of the photonic crystal. If broadband, these structures represent an ideal mirror to form compact vertical microcavity with 3D confinement of photons and polarization selectivity. Among numerous devices, low threshold VCSELs with remarkable and tunable modal properties have been demonstrated. Narrow band PCMs (or high Q resonators) have also been extensively used for surface addressable optoelectronic devices where an active material is embedded into the membrane, leading to the demonstration of low threshold surface emitting lasers, nonlinear bistables, optical traps... In this presentation, we will describe the main physical rules which govern the lifetime of photons in these resonant modes. More specifically, it will be emphasized that the Q factor of the PCM is determined, to the first order, by the integral overlap between the electromagnetic field distributions of the guided and free space modes and of the dielectric periodic perturbation which is applied to the homogeneous membrane to get the photonic crystal. It turns out that the symmetries of these distributions are of prime importance for the strength of the resonance. It will be shown that, by molding in-plane or vertical symmetries of Bloch modes, spectrally and spatially selective light absorbers or emitters can be designed. First proof of concept devices will be also presented.

  2. Keynote address

    Herzog, R.

    1985-01-01

    This paper addresses various aspects of the bases underlying the nuclear third party liability regime, and also analyses the distinction between danger and risk and the manner in which damage caused by flood, mass unemployment (economic damage mainly) and certain diseases is dealt with in the absence of liability provisions similar to those applicable to nuclear incidents. It also is suggested that the State because of its duty under the Basic Law to ensure adequate energy supplies, should be co-responsible for liability questions along with the nuclear operator. (NEA) [fr

  3. Electrolysis of water on (oxidized) metal surfaces

    Rossmeisl, Jan; Logadottir, Ashildur; Nørskov, Jens Kehlet

    2005-01-01

    Density functional theory calculations are used as the basis for an analysis of the electrochemical process, where by water is split to form molecular oxygen and hydrogen. We develop a method for obtaining the thermochemistry of the electrochemical water splitting process as a function of the bias...... directly from the electronic structure calculations. We consider electrodes of Pt(111) and Au(111) in detail and then discuss trends for a series of different metals. We show that the difficult step in the water splitting process is the formation of superoxy-type (OOH) species on the surface...... by the splitting of a water molecule on top an adsorbed oxygen atom. One conclusion is that this is only possible on metal surfaces that are (partly) oxidized. We show that the binding energies of the different intermediates are linearly correlated for a number of metals. In a simple analysis, where the linear...

  4. Keynote address

    Farlinger, W.

    1997-01-01

    In this second keynote address of the conference Mr. Farlinger, Chairman of Ontario Hydro, attempted to respond to some of the criticisms levelled at the Corporation in the course of the Macdonald Committee process. He appeared to be particularly vexed by the criticism of IPPSO, saying that in effect, they are' beating up on their only customer', at a time when Hydro is being pulled in several different directions, and was facing pressure from jurisdictional dispute with municipal utilities, (MEUs). Nevertheless, he agreed with the need for restructuring. He defended Hydro by saying that the Macdonald Report in fact represented a vindication of the position Ontario Hydro had taken, particularly on such issues as open competition, customer choice, rationalization of the distribution system, and termination of Hydro's monopoly position. At the same time, he objected to the Report's assertion that dismantling the generation system into smaller units would be in the best interest of the people of Ontario. He suggested that there would be several large US utility companies willing and able to fill the vacuum if there was no large company with its head office in Ontario to stake its claim to the provincial market

  5. Opening address

    Boening, K.

    2003-01-01

    The program of this 9th Meeting of the International Group on Research Reactors IGORR includes are quite a number of fascinating new research reactor projects in France, Germany, Russia, Canada, China, Thailand, and in Australia. In addition to the session about New Facilities there are interesting sessions on the Upgrades and on the Optimization of Operation and Utilization of existing research reactors, on Secondary Neutron Sources, on Neutron Scattering applications, and on the aspects of Safety, Licensing and Decommissioning. Two particular projects of new research reactors are mentioned specially: the TRR-II project in Taiwan, has unfortunately been terminated last year because of a change to anti-nuclear of the ruling parties in the government - and the new FRM-II in Munich, Germany, which will hopefully survive such a political change and receive its green light for nuclear start up in the very near future. The charter of IGORR and its objectives are part of this address: The International Group on Research Reactors IGORR was formed to facilitate the sharing of knowledge and experience among those institutions and individuals who are actively working to design, build, and promote new research reactors or to make significant upgrades to existing facilities. The main IGORR objectives are to promote contacts between its members, to identify and discuss problems of common interest, to distribute newsletters about once or twice every year and to organize meetings about once every one-and-a-half years

  6. Opening Address

    Yamada, T.

    2014-12-01

    Ladies and Gentlemen, it is my great honor and pleasure to present an opening address of the 3rd International Workshop on "State of the Art in Nuclear Cluster Physics"(SOTANCP3). On the behalf of the organizing committee, I certainly welcome all your visits to KGU Kannai Media Center belonging to Kanto Gakuin University, and stay in Yokohama. In particular, to whom come from abroad more than 17 countries, I would appreciate your participations after long long trips from your homeland to Yokohama. The first international workshop on "State of the Art in Nuclear Cluster Physics", called SOTANCP, was held in Strasbourg, France, in 2008, and the second one was held in Brussels, Belgium, in 2010. Then the third workshop is now held in Yokohama. In this period, we had the traditional 10th cluster conference in Debrecen, Hungary, in 2012. Thus we have the traditional cluster conference and SOTANCP, one after another, every two years. This obviously shows our field of nuclear cluster physics is very active and flourishing. It is for the first time in about 10 years to hold the international workshop on nuclear cluster physics in Japan, because the last cluster conference held in Japan was in Nara in 2003, about 10 years ago. The president in Nara conference was Prof. K. Ikeda, and the chairpersons were Prof. H. Horiuchi and Prof. I. Tanihata. I think, quite a lot of persons in this room had participated at the Nara conference. Since then, about ten years passed. So, this workshop has profound significance for our Japanese colleagues. The subjects of this workshop are to discuss "the state of the art in nuclear cluster physics" and also discuss the prospect of this field. In a couple of years, we saw significant progresses of this field both in theory and in experiment, which have brought better and new understandings on the clustering aspects in stable and unstable nuclei. I think, the concept of clustering has been more important than ever. This is true also in the

  7. Keynote address

    Davis, J.M.

    1991-01-01

    DOE biomass R ampersand D programs have the potential to provide America with both plentiful, clean-burning domestic transportation fuels and cost-competitive industrial and utility fuels, benefiting energy security in the United States. Biofuels developed under our programs will also help improve air quality, reduce greenhouse gases, reduce the large daily quantities of waste we produce, and revitalize rural America. These research motivations have been documented in the National Energy Strategy. DOE looks forward to expanding its biofuels research program and to forging a partnership with private sector for cost-shared commercialization of new fuels and vehicle technologies. Many alternative fuels (e.g., ethanol, methanol, compressed natural gas, propane, or electricity) are candidates for gaining market share. Indeed, there may be significant regional variation in the future fuel mix. Alcohol fuels from biomass, particularly ethanol, have the potential to make a major contribution. Currently, ethanol in the United States is almost entirely made from corn; and the limitations of that process are well known (e.g., costly feedstock, end product requiring subsidy to be competitive, use of fossil fuels in renewable feedstock production and processing, and potential adverse impact of corn ethanol production on the price of food). To address these concerns, the DOE biofuels program is pursuing an ambitious research program to develop the technologies needed to convert these crops into alternative transportation fuels, primarily cellulose-based ethanol and methanol. Program R ampersand D has reduced the estimated cost per gallon of cellulose-based ethanol from $3.60 in 1980 to the current $1.35, with a program goal of $0.60 by the year 2000. DOE is also investigating the thermochemical conversion of biomass to methanol. The program goal is to achieve commercial production of methanol (like ethanol) at the gasoline equivalent of $0.90 per gallon by the year 2000. 4 figs

  8. Dynamical simulation of electron transfer processes in self-assembled monolayers at metal surfaces using a density matrix approach

    Prucker, V.; Bockstedte, M.; Thoss, M.; Coto, P. B.

    2018-03-01

    A single-particle density matrix approach is introduced to simulate the dynamics of heterogeneous electron transfer (ET) processes at interfaces. The characterization of the systems is based on a model Hamiltonian parametrized by electronic structure calculations and a partitioning method. The method is applied to investigate ET in a series of nitrile-substituted (poly)(p-phenylene)thiolate self-assembled monolayers adsorbed at the Au(111) surface. The results show a significant dependence of the ET on the orbital symmetry of the donor state and on the molecular and electronic structure of the spacer.

  9. Dynamical simulation of electron transfer processes in self-assembled monolayers at metal surfaces using a density matrix approach.

    Prucker, V; Bockstedte, M; Thoss, M; Coto, P B

    2018-03-28

    A single-particle density matrix approach is introduced to simulate the dynamics of heterogeneous electron transfer (ET) processes at interfaces. The characterization of the systems is based on a model Hamiltonian parametrized by electronic structure calculations and a partitioning method. The method is applied to investigate ET in a series of nitrile-substituted (poly)(p-phenylene)thiolate self-assembled monolayers adsorbed at the Au(111) surface. The results show a significant dependence of the ET on the orbital symmetry of the donor state and on the molecular and electronic structure of the spacer.

  10. Welcome Address

    Kiku, H.

    2014-12-01

    Ladies and Gentlemen, It is an honor for me to present my welcome address in the 3rd International Workshop on "State of the Art in Nuclear Cluster Physics"(SOTANCP3), as the president of Kanto Gakuin University. Particularly to those from abroad more than 17 countries, I am very grateful for your participation after long long trips from your home to Yokohama. On the behalf of the Kanto Gakuin University, we certainly welcome your visit to our university and stay in Yokohama. First I would like to introduce Kanto Gakuin University briefly. Kanto Gakuin University, which is called KGU, traces its roots back to the Yokohama Baptist Seminary founded in 1884 in Yamate, Yokohama. The seminary's founder was Albert Arnold Bennett, alumnus of Brown University, who came to Japan from the United States to establish a theological seminary for cultivating and training Japanese missionaries. Now KGU is a major member of the Kanto Gakuin School Corporation, which is composed of two kindergartens, two primary schools, two junior high schools, two senior high schools as well as KGU. In this university, we have eight faculties with graduate school including Humanities, Economics, Law, Sciences and Engineering, Architecture and Environmental Design, Human and Environmental Studies, Nursing, and Law School. Over eleven thousands students are currently learning in our university. By the way, my major is the geotechnical engineering, and I belong to the faculty of Sciences and Engineering in my university. Prof. T. Yamada, here, is my colleague in the same faculty. I know that the nuclear physics is one of the most active academic fields in the world. In fact, about half of the participants, namely, more than 50 scientists, come from abroad in this conference. Moreover, I know that the nuclear physics is related to not only the other fundamental physics such as the elementary particle physics and astrophysics but also chemistry, medical sciences, medical cares, and radiation metrology

  11. Density functional study of a typical thiol tethered on a gold surface: ruptures under normal or parallel stretch

    Wang, Guan M; Sandberg, William C; Kenny, Steven D

    2006-01-01

    The mechanical and dynamical properties of a model Au(111)/thiol surface system were investigated by using localized atomic-type orbital density functional theory in the local density approximation. Relaxing the system gives a configuration where the sulfur atom forms covalent bonds to two adjacent gold atoms as the lowest energy structure. Investigations based on ab initio molecular dynamics simulations at 300, 350 and 370 K show that this tethering system is stable. The rupture behaviour between the thiol and the surface was studied by displacing the free end of the thiol. Calculated energy profiles show a process of multiple successive ruptures that account for experimental observations. The process features successive ruptures of the two Au-S bonds followed by the extraction of one S-bonded Au atom from the surface. The force required to rupture the thiol from the surface was found to be dependent on the direction in which the thiol was displaced, with values comparable with AFM measurements. These results aid the understanding of failure dynamics of Au(111)-thiol-tethered biosurfaces in microfluidic devices where fluidic shear and normal forces are of concern

  12. Ab Initio Calculations of the Electronic Properties of Polypyridine Transition Metal Complexes and Their Adsorption on Metal Surfaces in the Presence of Solvent and Counterions

    Jónsson, E. Ö.; Thygesen, Kristian Sommer; Ulstrup, Jens

    2011-01-01

    Os(II)/(III) and Co(II)/(III) polypyridine complexes in aqueous solution are robust molecular entities both in freely solute state and adsorbed on Au(111)- and Pt(111)-electrode surfaces. This class of robust coordination chemical compounds have recently been characterized by electrochemical...... of the complexes in the presence of the solvent, are conserved upon adsorption, whereas the structural features of the different oxidation states are completely lost upon adsorption under vacuum conditions. Detailed microscopic insight such as offered by the present study will be important in molecular...

  13. He atom surface scattering: Surface dynamics of insulators, overlayers and crystal growth

    1992-01-01

    Investigations have focused primarily on surface structure and dynamics of ionic insulators, epitaxial growth onto alkali halide crystals and multiphoton studies. The surface dynamics of RbCl has been re-examined. We have developed a simple force constant model which provides insight into the dynamics of KBr overlayers on NaCl(001), a system with a large lattice mismatch. The KBr/NaCl(001) results are compared to Na/Cu(001) and NaCl/Ge(001). We have completed epitaxial growth experiments for KBr onto RbCl(001). Slab dynamics calculations using a shell model for this system with very small lattice mismatch are being carried out in collaboration with Professor Manson of Clemson University and with Professor Schroeder in Regensburg, Germany. Extensive experiments on multiphoton scattering of helium atoms onto NaCl and, particularly, LiF have been carried out and the theory has been developed to a rather advanced stage by Professor Manson. This work will permit the extraction of more information from time-of-flight spectra. It is shown that the theoretical model provides a very good description of the multiphoton scattering from organic films. Work has started on self-assembling organic films on gold (alkyl thiols/Au(111)). We have begun to prepare and characterize the gold crystal; one of the group members has spent two weeks at the Oak Ridge National Laboratory learning the proper Au(111) preparation techniques. One of our students has carried out neutron scattering experiments on NiO, measuring both bulk phonon and magnon dispersion curves

  14. Electronic coupling effects and charge transfer between organic molecules and metal surfaces

    Forker, Roman

    2010-07-01

    We employ a variant of optical absorption spectroscopy, namely in situ differential reflectance spectroscopy (DRS), for an analysis of the structure-properties relations of thin epitaxial organic films. Clear correlations between the spectra and the differently intense coupling to the respective substrates are found. While rather broad and almost structureless spectra are obtained for a quaterrylene (QT) monolayer on Au(111), the spectral shape resembles that of isolated molecules when QT is grown on graphite. We even achieve an efficient electronic decoupling from the subjacent Au(111) by inserting an atomically thin organic spacer layer consisting of hexa-peri-hexabenzocoronene (HBC) with a noticeably dissimilar electronic behavior. These observations are further consolidated by a systematic variation of the metal substrate (Au, Ag, and Al), ranging from inert to rather reactive. For this purpose, 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) is chosen to ensure comparability of the molecular film structures on the different metals, and also because its electronic alignment on various metal surfaces has previously been studied with great intensity. We present evidence for ionized PTCDA at several interfaces and propose the charge transfer to be related to the electronic level alignment governed by interface dipole formation on the respective metals. (orig.)

  15. Growth dynamics of L-cysteine SAMs on single-crystal gold surfaces: a metastable deexcitation spectroscopy study

    Canepa, M.; Lavagnino, L.; Pasquali, L.; Moroni, R.; Bisio, F.; DeRenzi, V.; Terreni, S.; Mattera, L.

    2009-07-01

    We report on a metastable deexcitation spectroscopy investigation of the growth of L-cysteine layers deposited under UHV conditions on well-defined Au(110)- (1 × 2) and Au(111) surfaces. The interaction of He* with molecular orbitals gave rise to well-defined UPS-like Penning spectra which provided information on the SAM assembly dynamics and adsorption configurations. Penning spectra have been interpreted through comparison with molecular orbital DFT calculations of the free molecule and have been compared with XPS results of previous works. Regarding adsorption of first-layer molecules at room temperature (RT), two different growth regimes were observed. On Au(110), the absence of spectral features related to orbitals associated with SH groups indicated the formation of a compact SAM of thiolate molecules. On Au(111), the data demonstrated the simultaneous presence, since the early stages of growth, of strongly and weakly bound molecules, the latter showing intact SH groups. The different growth mode was tentatively assigned to the added rows of the reconstructed Au(110) surface which behave as extended defects effectively promoting the formation of the S-Au bond. The growth of the second molecular layer was instead observed to proceed similarly for both substrates. Second-layer molecules preferably adopt an adsorption configuration in which the SH group protrudes into the vacuum side.

  16. Growth dynamics of L-cysteine SAMs on single-crystal gold surfaces: a metastable deexcitation spectroscopy study

    Canepa, M; Lavagnino, L; Moroni, R; Bisio, F; Terreni, S; Mattera, L; Pasquali, L; De Renzi, V

    2009-01-01

    We report on a metastable deexcitation spectroscopy investigation of the growth of L-cysteine layers deposited under UHV conditions on well-defined Au(110)- (1 x 2) and Au(111) surfaces. The interaction of He* with molecular orbitals gave rise to well-defined UPS-like Penning spectra which provided information on the SAM assembly dynamics and adsorption configurations. Penning spectra have been interpreted through comparison with molecular orbital DFT calculations of the free molecule and have been compared with XPS results of previous works. Regarding adsorption of first-layer molecules at room temperature (RT), two different growth regimes were observed. On Au(110), the absence of spectral features related to orbitals associated with SH groups indicated the formation of a compact SAM of thiolate molecules. On Au(111), the data demonstrated the simultaneous presence, since the early stages of growth, of strongly and weakly bound molecules, the latter showing intact SH groups. The different growth mode was tentatively assigned to the added rows of the reconstructed Au(110) surface which behave as extended defects effectively promoting the formation of the S-Au bond. The growth of the second molecular layer was instead observed to proceed similarly for both substrates. Second-layer molecules preferably adopt an adsorption configuration in which the SH group protrudes into the vacuum side.

  17. Growth of pentacene on clean and modified gold surfaces

    Kaefer, Daniel; Ruppel, Lars; Witte, Gregor

    2007-01-01

    The growth and evolution of pentacene films on gold substrates have been studied. By combining complementary techniques including scanning tunneling microscopy, atomic force microscopy, scanning electron microscopy, near-edge x-ray-absorption fine structure, and x-ray diffraction, the molecular orientation, crystalline structure, and morphology of the organic films were characterized as a function of film thickness and growth parameters (temperature and rate) for different gold substrates ranging from Au(111) single crystals to polycrystalline gold. Moreover, the influence of precoating the various gold substrates with self-assembled monolayers (SAM's) of organothiols with different chemical terminations has been studied. On bare gold the growth of pentacene films is characterized by a pronounced dewetting while the molecular orientation within the resulting crystalline three-dimensional islands depends distinctly on the roughness and cleanliness of the substrate surface. After completion of the first wetting layer where molecules adopt a planar orientation parallel to the surface the molecules continue to grow in a tilted fashion: on Au(111) the long molecular axis is oriented parallel to the surface while on polycrystalline gold it is upstanding oriented and thus parallels the crystalline orientation of pentacene films grown on SiO 2 . On SAM pretreated gold substrates the formation of a wetting layer is effectively suppressed and pentacene grows in a quasi-layer-by-layer fashion with an upstanding orientation leading to rather smooth films. The latter growth mode is observed independently of the chemical termination of the SAM's and the roughness of the gold substrate. Possible reasons for the different growth mechanism as well as consequences for the assignment of spectroscopic data of thin pentacene film are discussed

  18. Electron transfer and redox metalloenzyme catalysis at the single-molecule level

    Hansen, Allan Glargaard; Zhang, Jingdong; Christensen, Hans Erik Mølager

    2004-01-01

    transfer (ET). Image interpretation requires, however, theoretical support, as STM represents both electronic and topographic features. Molecules with accessible redox levels offer other insight into electron tunneling mechanisms, addressed in detail for ET metalloproteins. We present here in situ STM...... of the blue redox metalloenzyme copper nitrite reductase (Achromobacter xylosoxidans, AxCuNiR) on Au(111) electrode surfaces modified by a self-assembled cysteamine monolayer. AxCuNiR displays strong nitrite reduction waves in this environment. AxCuNiR/cysteamine/ Au(111) surfaces were imaged at KNO2...

  19. Effect of Gold on the Corrosion Behavior of an Electroless Nickel/Immersion Gold Surface Finish

    Bui, Q. V.; Nam, N. D.; Yoon, J. W.; Choi, D. H.; Kar, A.; Kim, J. G.; Jung, S. B.

    2011-09-01

    The performance of surface finishes as a function of the pH of the utilized plating solution was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests in 3.5 wt.% NaCl solution. In addition, the surface finishes were examined by x-ray diffraction (XRD), and the contact angle of the liquid/solid interface was recorded. NiP films on copper substrates with gold coatings exhibited their highest coating performance at pH 5. This was attributed to the films having the highest protective efficiency and charge transfer resistance, lowest porosity value, and highest contact angle among those examined as a result of the strongly preferred Au(111) orientation and the improved surface wettability.

  20. Characterization of Functionalized Self-Assembled Monolayers and Surface-Attached Interlocking Molecules Using Near-Edge X-ray Absorption Fine Structure Spectroscopy

    Willey, T; Willey, T

    2004-01-01

    Quantitative knowledge of the fundamental structure and substrate binding, as well as the direct measurement of conformational changes, are essential to the development of self-assembled monolayers (SAMs) and surface-attached interlocking molecules, catenanes and rotaxanes. These monolayers are vital to development of nano-mechanical, molecular electronic, and biological/chemical sensor applications. This dissertation investigates properties of functionalized SAMs in sulfur-gold based adsorbed molecular monolayers using quantitative spectroscopic techniques including near-edge x-ray absorption fine structure spectroscopy (NEXAFS) and x-ray photoelectron spectroscopy (XPS). The stability of the gold-thiolate interface is addressed. A simple model SAM consisting of dodecanethiol adsorbed on Au(111) degrades significantly in less than 24 hours under ambient laboratory air. S 2p and O 1s XPS show the gold-bound thiolates oxidize to sulfinates and sulfonates. A reduction of organic material on the surface and a decrease in order are observed as the layer degrades. The effect of the carboxyl vs. carboxylate functionalization on SAM structure is investigated. Carboxyl-terminated layers consisting of long alkyl-chain thiols vs. thioctic acid with short, sterically separated, alkyl groups are compared and contrasted. NEXAFS shows a conformational change, or chemical switchability, with carboxyl groups tilted over and carboxylate endgroups more upright. Surface-attached loops and simple surface-attached rotaxanes are quantitatively characterized, and preparation conditions that lead to desired films are outlined. A dithiol is often insufficient to form a molecular species bound at each end to the substrate, while a structurally related disulfide-containing polymer yields surface-attached loops. Similarly, spectroscopic techniques show the successful production of a simple, surface-attached rotaxane that requires a ''molecular riveting'' step to hold the mechanically attached

  1. Nucleation and Early Stages of Layer-by-Layer Growth of Metal Organic Frameworks on Surfaces

    2015-01-01

    High resolution atomic force microscopy (AFM) is used to resolve the evolution of crystallites of a metal organic framework (HKUST-1) grown on Au(111) using a liquid-phase layer-by-layer methodology. The nucleation and faceting of individual crystallites is followed by repeatedly imaging the same submicron region after each cycle of growth and we find that the growing surface is terminated by {111} facets leading to the formation of pyramidal nanostructures for [100] oriented crystallites, and triangular [111] islands with typical lateral dimensions of tens of nanometres. AFM images reveal that crystallites can grow by 5–10 layers in each cycle. The growth rate depends on crystallographic orientation and the morphology of the gold substrate, and we demonstrate that under these conditions the growth is nanocrystalline with a morphology determined by the minimum energy surface. PMID:26709359

  2. Monitoring the on-surface synthesis of graphene nanoribbons by mass spectrometry

    Zhang, Wen

    2017-06-14

    We present a mass spectrometric approach to monitor and characterize the intermediates of graphene nanoribbon (GNR) formation by chemical vapor deposition (CVD) on top of Au(111) surfaces. Information regarding the repeating units, lengths, and termini can be obtained directly from the surface sample by a modified matrix assisted laser desorption/ionization (MALDI) method. The mass spectrometric results reveal ample oxidative side reactions under CVD conditions which can, however, be diminished drastically by introduction of protective H2 gas at ambient pressure. Simultaneously, addition of hydrogen extends the lengths of the oligophenylenes and thus the final GNRs. Moreover, the prematurely formed cyclodehydrogenation products during the oligomer growth can be assigned by the mass spectrometric method. The obtained mechanistic insights provide valuable information for optimizing and upscaling the bottom-up fabrication of GNRs. Given the important role of GNRs as semiconductors, the mass spectrometric characterization provides a readily available tool to improve and characterize their structural perfection.

  3. Understanding the adsorption of CuPc and ZnPc on noble metal surfaces by combining quantum-mechanical modelling and photoelectron spectroscopy.

    Huang, Yu Li; Wruss, Elisabeth; Egger, David A; Kera, Satoshi; Ueno, Nobuo; Saidi, Wissam A; Bucko, Tomas; Wee, Andrew T S; Zojer, Egbert

    2014-03-07

    Phthalocyanines are an important class of organic semiconductors and, thus, their interfaces with metals are both of fundamental and practical relevance. In the present contribution we provide a combined theoretical and experimental study, in which we show that state-of-the-art quantum-mechanical simulations are nowadays capable of treating most properties of such interfaces in a quantitatively reliable manner. This is shown for Cu-phthalocyanine (CuPc) and Zn-phthalocyanine (ZnPc) on Au(111) and Ag(111) surfaces. Using a recently developed approach for efficiently treating van der Waals (vdW) interactions at metal/organic interfaces, we calculate adsorption geometries in excellent agreement with experiments. With these geometries available, we are then able to accurately describe the interfacial electronic structure arising from molecular adsorption. We find that bonding is dominated by vdW forces for all studied interfaces. Concomitantly, charge rearrangements on Au(111) are exclusively due to Pauli pushback. On Ag(111), we additionally observe charge transfer from the metal to one of the spin-channels associated with the lowest unoccupied π-states of the molecules. Comparing the interfacial density of states with our ultraviolet photoelectron spectroscopy (UPS) experiments, we find that the use of a hybrid functionals is necessary to obtain the correct order of the electronic states.

  4. Understanding the Adsorption of CuPc and ZnPc on Noble Metal Surfaces by Combining Quantum-Mechanical Modelling and Photoelectron Spectroscopy

    Yu Li Huang

    2014-03-01

    Full Text Available Phthalocyanines are an important class of organic semiconductors and, thus, their interfaces with metals are both of fundamental and practical relevance. In the present contribution we provide a combined theoretical and experimental study, in which we show that state-of-the-art quantum-mechanical simulations are nowadays capable of treating most properties of such interfaces in a quantitatively reliable manner. This is shown for Cu-phthalocyanine (CuPc and Zn-phthalocyanine (ZnPc on Au(111 and Ag(111 surfaces. Using a recently developed approach for efficiently treating van der Waals (vdW interactions at metal/organic interfaces, we calculate adsorption geometries in excellent agreement with experiments. With these geometries available, we are then able to accurately describe the interfacial electronic structure arising from molecular adsorption. We find that bonding is dominated by vdW forces for all studied interfaces. Concomitantly, charge rearrangements on Au(111 are exclusively due to Pauli pushback. On Ag(111, we additionally observe charge transfer from the metal to one of the spin-channels associated with the lowest unoccupied π-states of the molecules. Comparing the interfacial density of states with our ultraviolet photoelectron spectroscopy (UPS experiments, we find that the use of a hybrid functionals is necessary to obtain the correct order of the electronic states.

  5. Allegheny County Addressing Landmarks

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset contains address points which represent physical address locations assigned by the Allegheny County addressing authority. Data is updated by County...

  6. Allegheny County Address Points

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset contains address points which represent physical address locations assigned by the Allegheny County addressing authority. Data is updated by County...

  7. Improved Re-Configurable Sliding Mode Controller for Reusable Launch Vehicle of Second Generation Addressing Aerodynamic Surface Failures and Thrust Deficiencies

    Shtessel, Yuri B.

    2002-01-01

    In this report we present a time-varying sliding mode control (TV-SMC) technique for reusable launch vehicle (RLV) attitude control in ascent and entry flight phases. In ascent flight the guidance commands Euler roll, pitch and yaw angles, and in entry flight it commands the aerodynamic angles of bank, attack and sideslip. The controller employs a body rate inner loop and the attitude outer loop, which are separated in time-scale by the singular perturbation principle. The novelty of the TVSMC is that both the sliding surface and the boundary layer dynamics can be varied in real time using the PD-eigenvalue assignment technique. This salient feature is used to cope with control command saturation and integrator windup in the presence of severe disturbance or control effector failure, which enhances the robustness and fault tolerance of the controller. The TV-SMC is developed and tuned up for the X-33 sub-orbital technology demonstration vehicle in launch and re-entry modes. A variety of nominal, dispersion and failure scenarios have tested via high fidelity 6DOF simulations using MAVERIC/SLIM simulation software.

  8. Quantum tunneling in real space: Tautomerization of single porphycene molecules on the (111) surface of Cu, Ag, and Au

    Kumagai, Takashi; Ladenthin, Janina N.; Litman, Yair; Rossi, Mariana; Grill, Leonhard; Gawinkowski, Sylwester; Waluk, Jacek; Persson, Mats

    2018-03-01

    Tautomerization in single porphycene molecules is investigated on Cu(111), Ag(111), and Au(111) surfaces by a combination of low-temperature scanning tunneling microscopy (STM) experiments and density functional theory (DFT) calculations. It is revealed that the trans configuration is the thermodynamically stable form of porphycene on Cu(111) and Ag(111), whereas the cis configuration occurs as a meta-stable form. The trans → cis or cis → trans conversion on Cu(111) can be induced in an unidirectional fashion by injecting tunneling electrons from the STM tip or heating the surface, respectively. We find that the cis ↔ cis tautomerization on Cu(111) occurs spontaneously via tunneling, verified by the negligible temperature dependence of the tautomerization rate below ˜23 K. Van der Waals corrected DFT calculations are used to characterize the adsorption structures of porphycene and to map the potential energy surface of the tautomerization on Cu(111). The calculated barriers are too high to be thermally overcome at cryogenic temperatures used in the experiment and zero-point energy corrections do not change this picture, leaving tunneling as the most likely mechanism. On Ag(111), the reversible trans ↔ cis conversion occurs spontaneously at 5 K and the cis ↔ cis tautomerization rate is much higher than on Cu(111), indicating a significantly smaller tautomerization barrier on Ag(111) due to the weaker interaction between porphycene and the surface compared to Cu(111). Additionally, the STM experiments and DFT calculations reveal that tautomerization on Cu(111) and Ag(111) occurs with migration of porphycene along the surface; thus, the translational motion couples with the tautomerization coordinate. On the other hand, the trans and cis configurations are not discernible in the STM image and no tautomerization is observed for porphycene on Au(111). The weak interaction of porphycene with Au(111) is closest to the gas-phase limit and therefore the absence

  9. PREFACE: Vibrations at surfaces Vibrations at surfaces

    Rahman, Talat S.

    2011-12-01

    Central Florida, Orlando, in March 2010. Several speakers at this meeting were invited to contribute to the special section in this issue. As is clear from the articles in this special section, the phenomenon of vibrations at surfaces continues to be a dynamic field of investigation. In fact, there is a resurgence of effort because the insights provided by surface dynamics are still fundamental to the development of an understanding of the microscopic factors that control surface structure formation, diffusion, reaction and structural stability. Examination of dynamics at surfaces thus complements and supplements the wealth of information that is obtained from real-space techniques such as scanning tunneling microscopy. Vibrational dynamics is, of course, not limited to surfaces. Surfaces are important since they provide immediate deviation from the bulk. They display how lack of symmetry can lead to new structures, new local atomic environments and new types of dynamical modes. Nanoparticles, large molecules and nanostructures of all types, in all kinds of local environments, provide further examples of regions of reduced symmetry and coordination, and hence display characteristic vibrational modes. Given the tremendous advance in the synthesis of a variety of nanostructures whose functionalization would pave the way for nanotechnology, there is even greater need to engage in experimental and theoretical techniques that help extract their vibrational dynamics. Such knowledge would enable a more complete understanding and characterization of these nanoscale systems than would otherwise be the case. The papers presented here provide excellent examples of the kind of information that is revealed by vibrations at surfaces. Vibrations at surface contents Poisoning and non-poisoning oxygen on Cu(410)L Vattuone, V Venugopal, T Kravchuk, M Smerieri, L Savio and M Rocca Modifying protein adsorption by layers of glutathione pre-adsorbed on Au(111)Anne Vallée, Vincent Humblot

  10. He atom-surface scattering: Surface dynamics of insulators, overlayers and crystal growth

    Safron, S.A.; Skofronick, J.G.

    1994-01-01

    This progress report describes work carried out in the study of surface structure and dynamics of ionic insulators, the microscopic interactions controlling epitaxial growth and the formation of overlayers, and energy exchange in multiphonon surface scattering. The approach used is to employ high resolution helium atom scattering to study the geometry and structural features of the surfaces. Experiments have been carried out on the surface dynamics of RbCl and preliminary studies done on CoO and NiO. Epitaxial growth and overlayer dynamics experiments on the systems NaCl/NaCl(001), KBr/NaCl(001), NaCl/KBr(001) and KBr/RbCl(001) have been performed. They have collaborated with two theoretical groups to explore models of overlayer dynamics with which to compare and to interpret their experimental results. They have carried out extensive experiments on the multiphonon scattering of helium atoms from NaCl and, particularly, LiF. Work has begun on self-assembling organic films on gold and silver surfaces (alkyl thiols/Au(111) and Ag(111))

  11. Surface single-molecule dynamics controlled by entropy at low temperatures

    Gehrig, J. C.; Penedo, M.; Parschau, M.; Schwenk, J.; Marioni, M. A.; Hudson, E. W.; Hug, H. J.

    2017-02-01

    Configuration transitions of individual molecules and atoms on surfaces are traditionally described using an Arrhenius equation with energy barrier and pre-exponential factor (attempt rate) parameters. Characteristic parameters can vary even for identical systems, and pre-exponential factors sometimes differ by orders of magnitude. Using low-temperature scanning tunnelling microscopy (STM) to measure an individual dibutyl sulfide molecule on Au(111), we show that the differences arise when the relative position of tip apex and molecule changes by a fraction of the molecule size. Altering the tip position on that scale modifies the transition's barrier and attempt rate in a highly correlated fashion, which results in a single-molecular enthalpy-entropy compensation. Conversely, appropriately positioning the STM tip allows selecting the operating point on the compensation line and modifying the transition rates. The results highlight the need to consider entropy in transition rates of single molecules, even at low temperatures.

  12. License Address List

    National Oceanic and Atmospheric Administration, Department of Commerce — Address list generated from National Saltwater Angler Registry. Used in conjunction with an address-based sample as per survey design.

  13. Addressing Ozone Layer Depletion

    Access information on EPA's efforts to address ozone layer depletion through regulations, collaborations with stakeholders, international treaties, partnerships with the private sector, and enforcement actions under Title VI of the Clean Air Act.

  14. Addressing the nuclear misconception

    Taylor, J.J.

    1998-01-01

    There is a perception, fostered and encouraged by the anti-nuclear groups, that the nuclear industry generates large quantities of waste with no idea how to deal with it, that it is unsafe, uneconomic, and environmentally damaging. The task is to change these perceptions, by demonstrating that the industry is not a problem in itself, but in fact provides solutions to problems. This paper, while primarily concerned with waste, addresses all of these issues as each has a bearing on the perception of the industry and therefore must be considered when addressing the issue of waste. The paper concludes that evidence exists to support the industry view, but that the mission of the industry should be to change the perception of the industry, by influencing and working together with its stake holders to address their concerns, rather than merely presenting more and more facts. (author)

  15. Addressing Sexual Harassment

    Young, Ellie L.; Ashbaker, Betty Y.

    2008-01-01

    This article discusses ways on how to address the problem of sexual harassment in schools. Sexual harassment--simply defined as any unwanted and unwelcome sexual behavior--is a sensitive topic. Merely providing students, parents, and staff members with information about the school's sexual harassment policy is insufficient; schools must take…

  16. Clean Os(0001) electronic surface states: A first-principle fully relativistic investigation

    Urru, Andrea; Dal Corso, Andrea

    2018-05-01

    We analyze the electronic structure of the Os(0001) surface by means of first-principle calculations based on Fully Relativistic (FR) Density Functional Theory (DFT) and a Projector Augmented-Wave (PAW) approach. We investigate surface states and resonances analyzing their spin-orbit induced energy splitting and their spin polarization. The results are compared with previously studied surfaces Ir(111), Pt(111), and Au(111). We do not find any surface state in the gap similar to the L-gap of the (111) fcc surfaces, but find Rashba split resonances that cross the Fermi level and, as in the recently studied Ir(111) surface, have a characteristic downward dispersion. Moreover, for some selected surface states we study the spin polarization with respect to k∥, the wave-vector parallel to the surface. In some cases, such as the Rashba split resonances, the spin polarization shows a smooth behavior with slow rotations, in others the rotation is faster, due to mixing and anti-crossing of the states.

  17. Voltammetry and In Situ Scanning Tunneling Microscopy of Cytochrome c Nitrite Reductase on Au(111)-Electrodes

    Gwyer, James; Zhang, Jingdong; Butt, Julea

    2006-01-01

    of the density and orientational distribution of NrfA molecules are disclosed. The submonolayer coverage resolved by in situ STM is readily reconciled with the failure to detect nonturnover signals in cyclic voltammetry of the NrfA films. The molecular structures show a range of lateral dimensions...... a direct approach to correlate electrocatalytic and molecular properties of the protein layer, a long-standing issue in protein film voltammetry....

  18. Rectifying behaviour of self assembled porphyrin/fullerene dyads on Au(111)

    Matino, F; Arima, V; Maruccio, G; Phaneuf, R J; Sole, R Del; Mele, G; Vasapollo, G; Cingolani, R; Rinaldi, R

    2007-01-01

    Here we present an Ultra High Vacuum Scanning Tunnelling Microscopy (UHVSTM) and Scanning Tunnelling Spectroscopy (STS) study of self assembled donor-acceptor conjugate dyads, consisting of fulleropyrrolidines and metallo-porphyrins immobilized on gold. The coverage in the fulleropyrrolidine layers was optimized up to obtain isolated protrusions which we identify with isolated dyads since their lateral dimensions are consistent with the fullerene size. The STS study reveals a diode-like asymmetric behaviour of the dyads, different from the surrounding areas. We investigate also the influence of the tunneling conditions on the rectifying ratio which is found to be dependent on the initial set point conditions and to increase by increasing the tip-sample distance

  19. Rectifying behaviour of self assembled porphyrin/fullerene dyads on Au(111)

    Matino, F [National Nanotechnology Laboratory (CNR-INFM)- Distretto Tecnologico ISUFI-Universita degli studi di Lecce - via Arnesano, 73100 Lecce (Italy); Arima, V [National Nanotechnology Laboratory (CNR-INFM)- Distretto Tecnologico ISUFI-Universita degli studi di Lecce - via Arnesano, 73100 Lecce (Italy); Maruccio, G [National Nanotechnology Laboratory (CNR-INFM)- Distretto Tecnologico ISUFI-Universita degli studi di Lecce - via Arnesano, 73100 Lecce (Italy); Phaneuf, R J [National Nanotechnology Laboratory (CNR-INFM)- Distretto Tecnologico ISUFI-Universita degli studi di Lecce - via Arnesano, 73100 Lecce (Italy); Sole, R Del [Dipartimento di Ingegneria dell' Innovazione - Universita degli Studi di Lecce- via Arnesano, 73100 Lecce (Italy); Mele, G [Dipartimento di Ingegneria dell' Innovazione - Universita degli Studi di Lecce- via Arnesano, 73100 Lecce (Italy); Vasapollo, G [Dipartimento di Ingegneria dell' Innovazione - Universita degli Studi di Lecce- via Arnesano, 73100 Lecce (Italy); Cingolani, R [National Nanotechnology Laboratory (CNR-INFM)- Distretto Tecnologico ISUFI-Universita degli studi di Lecce - via Arnesano, 73100 Lecce (Italy); Rinaldi, R [National Nanotechnology Laboratory (CNR-INFM)- Distretto Tecnologico ISUFI-Universita degli studi di Lecce - via Arnesano, 73100 Lecce (Italy)

    2007-04-15

    Here we present an Ultra High Vacuum Scanning Tunnelling Microscopy (UHVSTM) and Scanning Tunnelling Spectroscopy (STS) study of self assembled donor-acceptor conjugate dyads, consisting of fulleropyrrolidines and metallo-porphyrins immobilized on gold. The coverage in the fulleropyrrolidine layers was optimized up to obtain isolated protrusions which we identify with isolated dyads since their lateral dimensions are consistent with the fullerene size. The STS study reveals a diode-like asymmetric behaviour of the dyads, different from the surrounding areas. We investigate also the influence of the tunneling conditions on the rectifying ratio which is found to be dependent on the initial set point conditions and to increase by increasing the tip-sample distance.

  20. Diffusion mechanisms taking place at the early stages of cobalt deposition on Au(111)

    Oviedo, O A; Leiva, E P M; Mariscal, M M

    2008-01-01

    In the present work a detailed atomic-level analysis of some of the main diffusion mechanisms which take place during cobalt adatom deposition are studied within atom dynamics (AD) and the nudged elastic band (NEB) method. Our computer simulations reveal a very fast exchange between Co and Au atoms when the deposit is a single cobalt adatom. However, when the nucleus size increases, a decrease in the exchange probability is observed. Activation energies for different transitions are obtained using AD in combination with the NEB method

  1. Photoelectron spectroscopy of self-assembled monolayers of molecular switches on noble metal surfaces; Photoelektronenspektroskopie selbstorganisierter Adsorbatschichten aus molekularen Schaltern auf Edelmetalloberflaechen

    Heinemann, Nils

    2012-09-12

    Self-assembled monolayers (SAMs) of butanethiolate (C4) on single crystalline Au(111) surfaces were prepared by adsorption from solution. The thermally activated desorption behaviour of the C4 molecules from the gold substrate was examined by qualitative thermal desorption measurements (TDM), through this a desorption temperature T{sub Des}=473 K could be determined. With this knowledge, it was possible to produce samples of very good surface quality, by thermal treatment T{sub Sample}Au(111). The ex situ preparation scheme produced samples in p x {radical}(3) and p(4 x 4) phases, the high coverage ({radical}(3) x {radical}(3))R30 phase was not observed. The focus of the spectroscopy of C4/Au was on the samples of the p x {radical}(3) phase using two-photon photoemission spectroscopy (2PPE). The spectra revealed clear signatures of two unoccupied resonance states at energies E-E{sub F}=3.7 eV and 3.9 eV. The low-energy state was assigned to the characteristic {sigma}*-resonance associated with the Au-S bond of the thiolate. The energy of the other resonance state agreed well with an interface state reported before for SAMs of an other alkanethiol on Au(111) in a densely packed phase. Furthermore the 2PPE data indicated that the high quality of the ex situ prepared SAMs supported the formation of image potential states. The reversible photo- and thermally activated isomerization of the molecular switch 3-(4-(4-Hexyl-phenylazo)-phenoxy)-propane-1-thiol (ABT), deposited by self-assembly from solution on Au(111), was examined using laser-based photoelectron spectroscopy. Differences in the molecular dipole moment characteristic for the trans and the cis isomer of ABT were observed via changes in the sample work function, accessible by detection of the threshold energy for photoemission. A quantitative

  2. Addressing Software Security

    Bailey, Brandon

    2015-01-01

    Historically security within organizations was thought of as an IT function (web sites/servers, email, workstation patching, etc.) Threat landscape has evolved (Script Kiddies, Hackers, Advanced Persistent Threat (APT), Nation States, etc.) Attack surface has expanded -Networks interconnected!! Some security posture factors Network Layer (Routers, Firewalls, etc.) Computer Network Defense (IPS/IDS, Sensors, Continuous Monitoring, etc.) Industrial Control Systems (ICS) Software Security (COTS, FOSS, Custom, etc.)

  3. Counting addressing method: Command addressable element and extinguishing module

    Ristić Jovan D.

    2009-01-01

    Full Text Available The specific requirements that appear in addressable fire detection and alarm systems and the shortcomings of the existing addressing methods were discussed. A new method of addressing of detectors was proposed. The basic principles of addressing and responding of a called element are stated. Extinguishing module is specific subsystem in classic fire detection and alarm systems. Appearing of addressable fire detection and alarm systems didn't caused essential change in the concept of extinguishing module because of long calling period of such systems. Addressable fire security system based on counting addressing method reaches high calling rates and enables integrating of the extinguishing module in addressable system. Solutions for command addressable element and integrated extinguishing module are given in this paper. The counting addressing method was developed for specific requirements in fire detection and alarm systems, yet its speed and reliability justifies its use in the acquisition of data on slowly variable parameters under industrial conditions. .

  4. Light addressable gold electrodes

    Khalid, Waqas

    2011-07-01

    The main objective carried out in this dissertation was to fabricate Light Amplified Potentiometric sensors (LAPS) based upon the semiconductor nanoparticles (quantum dots) instead of its bulk form. Quantum dots (QDs) were opted for this device fabrication because of their superior fluorescent, electric and catalytic properties. Also in comparison to their bulk counterparts they will make device small, light weighted and power consumption is much lower. QDs were immobilized on a Au substrate via 1,4 benzene dithiol (BDT) molecule. Initially a self-assembled monolayer (SAM) of BDT was established on Au substrate. Because of SAM, the conductivity of Au substrate decreased dramatically. Furthermore QDs were anchored with the help of BDT molecule on Au substrate. When QDs immobilized on Au substrate (QD/Au) via BDT molecule were irradiated with UV-visible light, electron-hole pairs were generated in QDs. The surface defect states in QDs trapped the excited electrons and long lived electron-hole pairs were formed. By the application of an appropriate bias potential on Au substrate the electrons could be supplied or extracted from the QDs via tunneling through BDT. Thus a cathodic or anodic current could be observed depending upon bias potential under illumination. However without light illumination the QD/Au electrode remained an insulator. To improve the device different modifications were made, including different substrates (Au evaporated on glass, Au evaporated on mica sheets and Au sputtered on SiO{sub 2}/Si) and different dithiol molecules (capped and uncapped biphenyl 4,4' dithiol and capped and uncapped 4,4' dimercaptostilbenes) were tried. Also different QD immobilization techniques (normal incubation, spin coating, layer by layer assembly (LbL) of polyelectrolytes and heat immobilization) were employed. This device was able to detect electrochemically different analytes depending upon the QDs incorporated. For example CdS QDs were able to detect 4

  5. State-to-state inelastic and reactive molecular beam scattering from surfaces

    Lykke, K.R.; Kay, B.D.

    1990-01-01

    Resonantly enhanced multiphoton ionization (REMPI) laser spectroscopic and molecular beam-surface scattering techniques are coupled to study inelastic and reactive gas-surface scattering with state-to-state specificity. Rotational, vibrational, translational and angular distributions have been measured for the inelastic scattering of HCI and N 2 from Au(111). In both cases the scattering is direct-inelastic in nature and exhibits interesting dynamical features such as rotational rainbow scattering. In an effort to elucidate the dynamics of chemical reactions occurring on surfaces we have extended our quantum-resolved scattering studies to include the reactive scattering of a beam of gas phase H-atoms from a chlorinated metal surface M-CI. The nascent rotational and vibrational distributions of the HCI product are determined using REMPI. The thermochemistry for this reaction on Au indicates that the product formation proceeding through chemisorbed H-atoms is slightly endothermic while direct reaction of a has phase H-atom with M-CI is highly exothermic (ca. 50 kcal/mole). Details of the experimental techniques, results and implications regarding the scattering dynamics are discussed. 55 ref., 8 fig

  6. Forms of address in Isizulu

    2014-01-01

    M.A. (African Studies) The study deals with forms of address in isiZulu. Therefore, the various aspects of speech that play roles when addressing a person, the factors affecting forms of address in isiZulu and the effect of languages such as English, Afrikaans and other African languages on the forms of address in isiZulu are of interest. Research was conducted on forms of address in isiZulu in parts of Soweto and it was discovered that form of address are determined by different factors i...

  7. STM, SECPM, AFM and Electrochemistry on Single Crystalline Surfaces

    Ulrich Stimming

    2010-08-01

    Full Text Available Scanning probe microscopy (SPM techniques have had a great impact on research fields of surface science and nanotechnology during the last decades. They are used to investigate surfaces with scanning ranges between several 100 mm down to atomic resolution. Depending on experimental conditions, and the interaction forces between probe and sample, different SPM techniques allow mapping of different surface properties. In this work, scanning tunneling microscopy (STM in air and under electrochemical conditions (EC-STM, atomic force microscopy (AFM in air and scanning electrochemical potential microscopy (SECPM under electrochemical conditions, were used to study different single crystalline surfaces in electrochemistry. Especially SECPM offers potentially new insights into the solid-liquid interface by providing the possibility to image the potential distribution of the surface, with a resolution that is comparable to STM. In electrocatalysis, nanostructured catalysts supported on different electrode materials often show behavior different from their bulk electrodes. This was experimentally and theoretically shown for several combinations and recently on Pt on Au(111 towards fuel cell relevant reactions. For these investigations single crystals often provide accurate and well defined reference and support systems. We will show heteroepitaxially grown Ru, Ir and Rh single crystalline surface films and bulk Au single crystals with different orientations under electrochemical conditions. Image studies from all three different SPM methods will be presented and compared to electrochemical data obtained by cyclic voltammetry in acidic media. The quality of the single crystalline supports will be verified by the SPM images and the cyclic voltammograms. Furthermore, an outlook will be presented on how such supports can be used in electrocatalytic studies.

  8. Reclaiming unused IPv4 addresses

    IT Department

    2016-01-01

    As many people might know, the number of IPv4 addresses is limited and almost all have been allocated (see here and here for more information).   Although CERN has been allocated some 340,000 addresses, the way these are allocated across the site is not as efficient as we would like. As we face an increasing demand for IPv4 addresses with the growth in virtual machines, the IT Department’s Communication Systems Group will be reorganising address allocation during 2016 to make more efficient use of the IPv4 address ranges that have been allocated to CERN. We aim, wherever possible, to avoid giving out fixed IP addresses, and have all devices connected to the campus network obtain an address dynamically each time they connect. As a first stage, starting in February, IP addresses that have not been used for more than 9 months will be reclaimed. No information about the devices concerned will be deleted from LANDB, but a new IP address will have to be requested if they are ever reconnected to t...

  9. Port virtual addressing for PC

    Bolanos, L.; Arista, E.; Osorio Deliz, J.F.

    1997-01-01

    Instruments for nuclear signal measurements based on add-on card for a personal computer (PC) are designed often. Then one faces the problem of the addressing of data input/output devices which show an integration level or intelligence that makes the use of several port address indispensable, and these are limited in the PC. The virtual addressing offers the advantage of the occupation of few addresses to accede to many of these devices. The principles of this technique and the appliances of a solution in radiometric in a radiometric card based on programmed logic are discussed in this paper

  10. Transformed composite sequences for improved qubit addressing

    Merrill, J. True; Doret, S. Charles; Vittorini, Grahame; Addison, J. P.; Brown, Kenneth R.

    2014-10-01

    Selective laser addressing of a single atom or atomic ion qubit can be improved using narrow-band composite pulse sequences. We describe a Lie-algebraic technique to generalize known narrow-band sequences and introduce sequences related by dilation and rotation of sequence generators. Our method improves known narrow-band sequences by decreasing both the pulse time and the residual error. Finally, we experimentally demonstrate these composite sequences using 40Ca+ ions trapped in a surface-electrode ion trap.

  11. Investigation of Supramolecular Coordination Self-Assembly and Polymerization Confined on Metal Surfaces Using Scanning Tunneling Microscopy

    Lin, Tao

    Organic molecules are envisioned as the building blocks for design and fabrication of functional devices in future, owing to their versatility, low cost and flexibility. Although some devices such as organic light-emitting diode (OLED) have been already applied in our daily lives, the field is still in its infancy and numerous challenges still remain. In particular, fundamental understanding of the process of organic material fabrication at a molecular level is highly desirable. This thesis focuses on the design and fabrication of supramolecular and macromolecular nanostructures on a Au(111) surface through self-assembly, polymerization and a combination of two. We used scanning tunneling microscopy (STM) as an experimental tool and Monte Carlo (MC) and kinetic Monte Carlo (KMC) simulations as theoretical tools to characterize the structures of these systems and to investigate the mechanisms of the self-assembly and polymerization processes at a single-molecular level. The results of this thesis consist of four parts as below: Part I addresses the mechanisms of two-dimensional multicomponent supramolecular self-assembly via pyridyl-Fe-terpyridyl coordination. Firstly, we studied four types of self-assembled metal-organic systems exhibiting different dimensionalities using specifically-designed molecular building blocks. We found that the two-dimensional system is under thermodynamic controls while the systems of lower dimension are under kinetic controls. Secondly, we studied the self-assembly of a series of cyclic supramolecular polygons. Our results indicate that the yield of on-surface cyclic polygon structures is very low independent of temperature and concentration and this phenomenon can be attributed to a subtle competition between kinetic and thermodynamic controls. These results shed light on thermodynamic and kinetic controls in on-surface coordination self-assembly. Part II addresses the two-dimensional supramolecular self-assembly of porphyrin

  12. Long-Range Interfacial Electrochemical Electron Transfer of Pseudomonas aeruginosa Azurin-Gold Nanoparticle Hybrid Systems

    Jensen, Palle Skovhus; Chi, Qijin; Zhang, Jingdong

    2009-01-01

    We have prepared a "hybrid" of the blue copper protein azurin (Pseudomonas aeruginosa) and a 3 nm gold nanoparticle (AuNP). The AuNP/azurin hybrid was assembled on a Au(111)-electrode surface in a two-step process. The AuNP was first attached to the Au(111) electrode via Au-S chemisorption of a 4...

  13. Excitation mechanism in the photoisomerization of a surface-bound azobenzene derivative: Role of the metallic substrate

    Hagen, Sebastian; Kate, Peter; Leyssner, Felix; Nandi, Dhananjay; Wolf, Martin; Tegeder, Petra

    2008-10-01

    Two-photon photoemission spectroscopy is employed to elucidate the electronic structure and the excitation mechanism in the photoinduced isomerization of the molecular switch tetra-tert-butyl-azobenzene (TBA) adsorbed on Au(111). Our results demonstrate that the optical excitation and the mechanism of molecular switching at a metal surface is completely different compared to the corresponding process for the free molecule. In contrast to direct (intramolecular) excitation operative in the isomerization in the liquid phase, the conformational change in the surface-bound TBA is driven by a substrate-mediated charge transfer process. We find that photoexcitation above a threshold hν ≈2.2 eV leads to hole formation in the Au d-band followed by a hole transfer to the highest occupied molecular orbital of TBA. This transiently formed positive ion resonance subsequently results in a conformational change. The photon energy dependent photoisomerization cross section exhibit an unusual shape for a photochemical reaction of an adsorbate on a metal surface. It shows a thresholdlike behavior below hν ≈2.2 eV and above hν ≈4.4 eV. These thresholds correspond to the minimum energy required to create single or multiple hot holes in the Au d-bands, respectively. This study provides important new insights into the use of light to control the structure and function of molecular switches in direct contact with metal electrodes.

  14. Excitation mechanism in the photoisomerization of a surface-bound azobenzene derivative: Role of the metallic substrate

    Hagen, Sebastian; Kate, Peter; Leyssner, Felix; Nandi, Dhananjay; Wolf, Martin; Tegeder, Petra

    2008-01-01

    Two-photon photoemission spectroscopy is employed to elucidate the electronic structure and the excitation mechanism in the photoinduced isomerization of the molecular switch tetra-tert-butyl-azobenzene (TBA) adsorbed on Au(111). Our results demonstrate that the optical excitation and the mechanism of molecular switching at a metal surface is completely different compared to the corresponding process for the free molecule. In contrast to direct (intramolecular) excitation operative in the isomerization in the liquid phase, the conformational change in the surface-bound TBA is driven by a substrate-mediated charge transfer process. We find that photoexcitation above a threshold hν≅2.2 eV leads to hole formation in the Au d-band followed by a hole transfer to the highest occupied molecular orbital of TBA. This transiently formed positive ion resonance subsequently results in a conformational change. The photon energy dependent photoisomerization cross section exhibit an unusual shape for a photochemical reaction of an adsorbate on a metal surface. It shows a thresholdlike behavior below hν≅2.2 eV and above hν≅4.4 eV. These thresholds correspond to the minimum energy required to create single or multiple hot holes in the Au d-bands, respectively. This study provides important new insights into the use of light to control the structure and function of molecular switches in direct contact with metal electrodes.

  15. In situ fabrication of quasi-free-standing epitaxial graphene nanoflakes on gold.

    Leicht, Philipp; Zielke, Lukas; Bouvron, Samuel; Moroni, Riko; Voloshina, Elena; Hammerschmidt, Lukas; Dedkov, Yuriy S; Fonin, Mikhail

    2014-04-22

    Addressing the multitude of electronic phenomena theoretically predicted for confined graphene structures requires appropriate in situ fabrication procedures yielding graphene nanoflakes (GNFs) with well-defined geometries and accessible electronic properties. Here, we present a simple strategy to fabricate quasi-free-standing GNFs of variable sizes, performing temperature programmed growth of graphene flakes on the Ir(111) surface and subsequent intercalation of gold. Using scanning tunneling microscopy (STM), we show that epitaxial GNFs on a perfectly ordered Au(111) surface are formed while maintaining an unreconstructed, singly hydrogen-terminated edge structure, as confirmed by the accompanying density functional theory (DFT) calculations. Using tip-induced lateral displacement of GNFs, we demonstrate that GNFs on Au(111) are to a large extent decoupled from the Au(111) substrate. The direct accessibility of the electronic states of a single GNF is demonstrated upon analysis of the quasiparticle interference patterns obtained by low-temperature STM. These findings open up an interesting playground for diverse investigations of graphene nanostructures with possible implications for device fabrication.

  16. Addressing problems of employee performance.

    McConnell, Charles R

    2011-01-01

    Employee performance problems are essentially of 2 kinds: those that are motivational in origin and those resulting from skill deficiencies. Both kinds of problems are the province of the department manager. Performance problems differ from problems of conduct in that traditional disciplinary processes ordinarily do not apply. Rather, performance problems are addressed through educational and remedial processes. The manager has a basic responsibility in ensuring that everything reasonable is done to help each employee succeed. There are a number of steps the manager can take to address employee performance problems.

  17. New pathway to prepare gold nanoparticles and their applications in catalysis and surface-enhanced Raman scattering.

    Chang, Chun-Chao; Yang, Kuang-Hsuan; Liu, Yu-Chuan; Hsu, Ting-Chu

    2012-05-01

    As shown in the literature, additional energies are necessary for the reduction of positively charged noble metal ions to prepare metal nanoparticles (NPs). In this work, we report a new green pathway to prepare Au NPs in neutral 0.1M NaCl aqueous solutions from bulk Au substrates without addition of any stabilizer and reductant just via aid of natural chitosan (Ch) at room temperature. Au- and Ch-containing complexes in aqueous solution were electrochemically prepared. The role of Ch is just an intermediate to perform electron transfer with Au NPs. The stability of these prepared Au NPs is well maintained by Au NPs themselves with slightly positively charged Au remained on the surface of Au NPs. The particle size of prepared spherical Au (111) NPs is ca. 15 nm in diameter. Moreover, increasing the pH of preparation solutions can be contributive to preparing concentrated Au NPs in solutions. The prepared Au NPs are surface-enhanced Raman scattering (SERS)-active for probe molecules of Rhodamine 6G. They also demonstrate significantly catalytic activity for decomposition of acetaldehyde in rice wine. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. Zone memories and pseudorandom addressing

    Marino, D.; Mirizzi, N.; Stella, R.; Visaggio, G.

    1975-01-01

    A quantitative comparison between zone memories, pseudorandom addressed memories and an alternative special purpose memory (spread zone memory) in which the distance between any two transformed descriptors, at first adjacent, is independent of the descriptors pair and results the maximum one is presented. This memory has not been particularly considered at present in spite of its efficiency and its simple implementation

  19. Introduction to IP address management

    Rooney, Tim

    2010-01-01

    "The book begins with a basic overview of IP networking, followed by chapters describing each of the three core IPAM technologies: IPv4 and IPv6 addressing, DHCP, and DNS. The next three chapters describe IPAM management techniques and practice, followed by chapters on IPv4-IPv6 co-existence, security and the IPAM business case"--

  20. Excited-state potential-energy surfaces of metal-adsorbed organic molecules from linear expansion Δ-self-consistent field density-functional theory (ΔSCF-DFT).

    Maurer, Reinhard J; Reuter, Karsten

    2013-07-07

    Accurate and efficient simulation of excited state properties is an important and much aspired cornerstone in the study of adsorbate dynamics on metal surfaces. To this end, the recently proposed linear expansion Δ-self-consistent field method by Gavnholt et al. [Phys. Rev. B 78, 075441 (2008)] presents an efficient alternative to time consuming quasi-particle calculations. In this method, the standard Kohn-Sham equations of density-functional theory are solved with the constraint of a non-equilibrium occupation in a region of Hilbert-space resembling gas-phase orbitals of the adsorbate. In this work, we discuss the applicability of this method for the excited-state dynamics of metal-surface mounted organic adsorbates, specifically in the context of molecular switching. We present necessary advancements to allow for a consistent quality description of excited-state potential-energy surfaces (PESs), and illustrate the concept with the application to Azobenzene adsorbed on Ag(111) and Au(111) surfaces. We find that the explicit inclusion of substrate electronic states modifies the topologies of intra-molecular excited-state PESs of the molecule due to image charge and hybridization effects. While the molecule in gas phase shows a clear energetic separation of resonances that induce isomerization and backreaction, the surface-adsorbed molecule does not. The concomitant possibly simultaneous induction of both processes would lead to a significantly reduced switching efficiency of such a mechanism.

  1. Addressing the workforce pipeline challenge

    Leonard Bond; Kevin Kostelnik; Richard Holman

    2006-11-01

    A secure and affordable energy supply is essential for achieving U.S. national security, in continuing U.S. prosperity and in laying the foundations to enable future economic growth. To meet this goal the next generation energy workforce in the U.S., in particular those needed to support instrumentation, controls and advanced operations and maintenance, is a critical element. The workforce is aging and a new workforce pipeline, to support both current generation and new build has yet to be established. The paper reviews the challenges and some actions being taken to address this need.

  2. A Life’s Addresses

    Balle, Søren Hattesen

    According to Jonathan Culler’s essay ”Apostrophe”, ”…post-enlightenment poetry seeks to overcome the alienation of subject from object”, and “apostrophe takes the crucial step of constituting the object as another subject with whom the poetic subject might hope to strike up a harmonious relations......According to Jonathan Culler’s essay ”Apostrophe”, ”…post-enlightenment poetry seeks to overcome the alienation of subject from object”, and “apostrophe takes the crucial step of constituting the object as another subject with whom the poetic subject might hope to strike up a harmonious...... to a number of different aspects of Koch’s own life such as marijuana, the Italian language, World War Two, etc. In this way, the book quite conventionally inscribes itself in the tradition of post-enlightenment apostrophic poetry as characterized by Culler, just as all its poems belong to the favourite......, are literally troped as and addressed in the manner of so many acquaintances, personal connections, relatives, friends, lovers, and family members in Koch’s life. My main claim is that Koch’s poetics in New Addresses is one that slightly dislocates the romantic dichotomy between the world of things...

  3. Organizing and addressing magnetic molecules.

    Gatteschi, Dante; Cornia, Andrea; Mannini, Matteo; Sessoli, Roberta

    2009-04-20

    Magnetic molecules ranging from simple organic radicals to single-molecule magnets (SMMs) are intensively investigated for their potential applications in molecule-based information storage and processing. The goal of this Article is to review recent achievements in the organization of magnetic molecules on surfaces and in their individual probing and manipulation. We stress that the inherent fragility and redox sensitivity of most SMM complexes, combined with the noninnocent role played by the substrate, ask for a careful evaluation of the structural and electronic properties of deposited molecules going beyond routine methods for surface analysis. Detailed magnetic information can be directly obtained using X-ray magnetic circular dichroism or newly emerging scanning probe techniques with magnetic detection capabilities.

  4. Line-on-line organic-organic heteroepitaxy of quaterrylene on hexa-peri-hexabenzocoronene on Au(111).

    Kasemann, Daniel; Wagner, Christian; Forker, Roman; Dienel, Thomas; Müllen, Klaus; Fritz, Torsten

    2009-11-03

    In a recent paper, we discussed the optical properties of a heterostructure consisting of a highly ordered monolayer of quaterrylene (QT), electronically decoupled from the gold substrate by a predeposited epitaxial monolayer of hexa-peri-hexabenzocoronene (HBC). Here we now present the detailed structural investigation of this organic double-layer system. We show that the structure of the heterosystem can be identified as line-on-line coincidence (lol), a new type of epitaxy discovered by us previously for the system 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) on HBC on highly oriented pyrolytic graphite (HOPG). Additionally, we provide evidence on the basis of advanced potential energy calculations that indeed energetic gain drives this lol growth mode.

  5. Analysis of functional organic molecules at noble metal surfaces by means of vibrational spectroscopies

    Leyssner, Felix

    2011-10-24

    The goal of this work is to optimize the efficiency of photoinduced molecular switching processes on surfaces via controlled variations of the adsorption and electronic properties of the switch. We investigated the influence of external stimuli, i.e. photons and thermal activation, on surface bound molecular switches undergoing trans/cis-isomerizations and ring-opening/closing-reactions, respectively. High resolution electron energy loss spectroscopy (HREELS) and sum-frequency generation (SFG) spectroscopy have been used as the main tools to investigate the adsorption behavior and the molecular switching properties. Two basic concepts of coupling the molecular switch to the surface have been studied: (i) physisorbed or weakly chemisorbed systems deposited on noble metal surfaces under UHV conditions and (ii) molecular switches bound covalently via anchor groups. In the HREELS study following concept (i), we investigated the adsorption geometry and isomerization behavior of various molecular switches on metal substrates which are able to undergo a photoinduced trans/cis-isomerization in solution. We investigated three isoelectronic molecules on Au where we systematically changed the photochemically active group from the diazo-group in an azobenzene-derivative (on Cu(111)) to the imine-group, and the vinylene-group, respectively. Finding the photoisomerization quenched for all systems we observed considerable differences in their thermal isomerization behavior. Comparable we find the photoinduced ring-opening/closing-reaction of spiropyran quenched on Au(111) but a thermally induced ring-opening reaction resulting in the open form being strongly stabilized by the metal. SFG spectroscopy is employed to investigate the reversible, photoinduced trans/cis-isomerization of an azobenzene-functionalized self-assembled monolayer (SAM) on gold using a tripodal linker system. In consequence of the decoupling provided by the tripodal linker, the switching behavior of the

  6. First keynote address - biological monitoring

    Turner, J.E.

    1984-01-01

    The author describes the interplay of physical research and the practice of radiation protection. There are both analogies in and differences between the problems of health protection from radiation and chemical pollutants. In formulating research objectives for synfuel technologies, it is important to take what lessons there are to be learned from the radiation experience. The regulation of the exposure of persons to radiation probably rests on a firmer scientific basis than does the regulation of exposure to many toxic chemicals. Some things in radiation protection - in both applied work and in research - should help to guide in approaching chemicals. The second section of this paper gives a brief description of the practice of radiation protection. The next section mentions some fundamental deficiencies that exist in radiation protection. Some physical research avenues illustrate how such deficiencies are being addressed as part of an integrated radiation research program. In the fourth section the author focuses on chemical pollutants, drawing some lessons from the radiation experience

  7. A region addresses patient safety.

    Feinstein, Karen Wolk; Grunden, Naida; Harrison, Edward I

    2002-06-01

    The Pittsburgh Regional Healthcare Initiative (PRHI) is a coalition of 35 hospitals, 4 major insurers, more than 30 major and small-business health care purchasers, dozens of corporate and civic leaders, organized labor, and partnerships with state and federal government all working together to deliver perfect patient care throughout Southwestern Pennsylvania. PRHI believes that in pursuing perfection, many of the challenges facing today's health care delivery system (eg, waste and error in the delivery of care, rising costs, frustration and shortage among clinicians and workers, financial distress, overcapacity, and lack of access to care) will be addressed. PRHI has identified patient safety (nosocomial infections and medication errors) and 5 clinical areas (obstetrics, orthopedic surgery, cardiac surgery, depression, and diabetes) as ideal starting points. In each of these areas of work, PRHI partners have assembled multifacility/multidisciplinary groups charged with defining perfection, establishing region-wide reporting systems, and devising and implementing recommended improvement strategies and interventions. Many design and conceptual elements of the PRHI strategy are adapted from the Toyota Production System and its Pittsburgh derivative, the Alcoa Business System. PRHI is in the proof-of-concept phase of development.

  8. Spin crossover in Fe(phen)2(NCS)2 complexes on metallic surfaces

    Gruber, Manuel; Miyamachi, Toshio; Davesne, Vincent; Bowen, Martin; Boukari, Samy; Wulfhekel, Wulf; Alouani, Mebarek; Beaurepaire, Eric

    2017-03-01

    In this review, we give an overview on the spin crossover of Fe(phen)2(NCS)2 complexes adsorbed on Cu(100), Cu2N/Cu(100), Cu(111), Co/Cu(111), Co(100), Au(100), and Au(111) surfaces. Depending on the strength of the interaction of the molecules with the substrates, the spin crossover behavior can be drastically changed. Molecules in direct contact with non-magnetic metallic surfaces coexist in both the high- and low-spin states but cannot be switched between the two. Our analysis shows that this is due to a strong interaction with the substrate in the form of a chemisorption that dictates the spin state of the molecules through its adsorption geometry. Upon reducing the interaction to the surface either by adding a second molecular layer or inserting an insulating thin film of Cu2N, the spin crossover behavior is restored and molecules can be switched between the two states with the help of scanning tunneling microscopy. Especially on Cu2N, the two states of single molecules are stable at low temperature and thus allow the realization of a molecular memory. Similarly, the molecules decoupled from metallic substrates in the second or higher layers display thermally driven spin crossover as has been revealed by X-ray absorption spectroscopy. Finally, we discuss the situation when the complex is brought into contact with a ferromagnetic substrate. This leads to a strong exchange coupling between the Fe spin in the high-spin state and the magnetization of the substrate as deduced from spin-polarized scanning tunneling spectroscopy and ab initio calculation.

  9. Addressing uncertainty in atomistic machine learning

    Peterson, Andrew A.; Christensen, Rune; Khorshidi, Alireza

    2017-01-01

    Machine-learning regression has been demonstrated to precisely emulate the potential energy and forces that are output from more expensive electronic-structure calculations. However, to predict new regions of the potential energy surface, an assessment must be made of the credibility of the predi......Machine-learning regression has been demonstrated to precisely emulate the potential energy and forces that are output from more expensive electronic-structure calculations. However, to predict new regions of the potential energy surface, an assessment must be made of the credibility...... of the predictions. In this perspective, we address the types of errors that might arise in atomistic machine learning, the unique aspects of atomistic simulations that make machine-learning challenging, and highlight how uncertainty analysis can be used to assess the validity of machine-learning predictions. We...... suggest this will allow researchers to more fully use machine learning for the routine acceleration of large, high-accuracy, or extended-time simulations. In our demonstrations, we use a bootstrap ensemble of neural network-based calculators, and show that the width of the ensemble can provide an estimate...

  10. Realization and Addressing Analysis In Blockchain Bitcoin

    Sakti Arief Daulay, Raja; Michrandi Nasution, Surya; Paryasto, Marisa W.

    2017-11-01

    The implementation research and analyze address blockchain on this bitcoin will have the results that refers to making address bitcoin a safe and boost security of address the bitcoin. The working mechanism of blockchain in making address bitcoin which is already in the blockchain system.

  11. EDITORIAL: Molecular switches at surfaces Molecular switches at surfaces

    Weinelt, Martin; von Oppen, Felix

    2012-10-01

    electron-vibration coupling in transport through single moleculesKatharina J Franke and Jose Ignacio Pascual Vibrational heating in single-molecule switches: an energy-dependent density-of-states approachT Brumme, R Gutierrez and G Cuniberti Reversible switching of single tin phthalocyanine molecules on the InAs(111)A surfaceC Nacci, K Kanisawa and S Fölsch Tuning the interaction between carbon nanotubes and dipole switches: the influence of the change of the nanotube-spiropyran distanceP Bluemmel, A Setaro, C Maity, S Hecht and S Reich Carbon nanotubes as substrates for molecular spiropyran-based switchesE Malic, A Setaro, P Bluemmel, Carlos F Sanz-Navarro, Pablo Ordejón, S Reich and A Knorr Ultrafast dynamics of dithienylethenes differently linked to the surface of TiO2 nanoparticlesLars Dworak, Marc Zastrow, Gehad Zeyat, Karola Rück-Braun and Josef Wachtveitl Switching the electronic properties of Co-octaethylporphyrin molecules on oxygen-covered Ni films by NO adsorptionC F Hermanns, M Bernien, A Krüger, J Miguel and W Kuch STM-switching of organic molecules on semiconductor surfaces: an above threshold density matrix model for 1,5 cyclooctadiene on Si(100)K Zenichowski, Ch Nacci, S Fölsch, J Dokić, T Klamroth and P Saalfrank A switch based on self-assembled thymineFatih Kalkan, Michael Mehlhorn and Karina Morgenstern The growth and electronic structure of azobenzene-based functional molecules on layered crystalsJ Iwicki, E Ludwig, J Buck, M Kalläne, F Köhler, R Herges, L Kipp and K Rossnagel Voltage-dependent conductance states of a single-molecule junctionY F Wang, N Néel, J Kröger, H Vázquez, M Brandbyge, B Wang and R Berndt Molecules with multiple switching units on a Au(111) surface: self-organization and single-molecule manipulationJohannes Mielke, Sofia Selvanathan, Maike Peters, Jutta Schwarz, Stefan Hecht and Leonhard Grill Preparing and regulating a bi-stable molecular switch by atomic manipulationS Sakulsermsuk, R E Palmer and P A Sloan Mixed self

  12. Addressing submarine geohazards through scientific drilling

    Camerlenghi, A.

    2009-04-01

    Natural submarine geohazards (earthquakes, volcanic eruptions, landslides, volcanic island flank collapses) are geological phenomena originating at or below the seafloor leading to a situation of risk for off-shore and on-shore structures and the coastal population. Addressing submarine geohazards means understanding their spatial and temporal variability, the pre-conditioning factors, their triggers, and the physical processes that control their evolution. Such scientific endeavour is nowadays considered by a large sector of the international scientific community as an obligation in order to contribute to the mitigation of the potentially destructive societal effects of submarine geohazards. The study of submarine geohazards requires a multi-disciplinary scientific approach: geohazards must be studied through their geological record; active processes must be monitored; geohazard evolution must be modelled. Ultimately, the information must be used for the assessment of vulnerability, risk analysis, and development of mitigation strategies. In contrast with the terrestrial environment, the oceanic environment is rather hostile to widespread and fast application of high-resolution remote sensing techniques, accessibility for visual inspection, sampling and installation of monitoring stations. Scientific Drilling through the IODP (including the related pre site-survey investigations, sampling, logging and in situ measurements capability, and as a platform for deployment of long term observatories at the surface and down-hole) can be viewed as the centre of gravity of an international, coordinated, multi-disciplinary scientific approach to address submarine geohazards. The IODP Initial Science Plan expiring in 2013 does not address openly geohazards among the program scientific objectives. Hazards are referred to mainly in relation to earthquakes and initiatives towards the understanding of seismogenesis. Notably, the only drilling initiative presently under way is the

  13. Chemically Addressable Perovskite Nanocrystals for Light-Emitting Applications

    Sun, Haizhu

    2017-07-10

    Whereas organic–inorganic hybrid perovskite nanocrystals (PNCs) have remarkable potential in the development of optoelectronic materials, their relatively poor chemical and colloidal stability undermines their performance in optoelectronic devices. Herein, this issue is addressed by passivating PNCs with a class of chemically addressable ligands. The robust ligands effectively protect the PNC surfaces, enhance PNC solution processability, and can be chemically addressed by thermally induced crosslinking or radical-induced polymerization. This thin polymer shield further enhances the photoluminescence quantum yields by removing surface trap states. Crosslinked methylammonium lead bromide (MAPbBr3) PNCs are applied as active materials to build light-emitting diodes that have low turn-on voltages and achieve a record luminance of over 7000 cd m−2, around threefold better than previous reported MA-based PNC devices. These results indicate the great potential of this ligand passivation approach for long lifespan, highly efficient PNC light emitters.

  14. 33 CFR 135.9 - Fund address.

    2010-07-01

    ... FINANCIAL RESPONSIBILITY AND COMPENSATION OFFSHORE OIL POLLUTION COMPENSATION FUND General § 135.9 Fund address. The address to which correspondence relating to the Coast Guard's administration of the Fund... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Fund address. 135.9 Section 135.9...

  15. Reading handprinted addresses on IRS tax forms

    Ramanaprasad, Vemulapati; Shin, Yong-Chul; Srihari, Sargur N.

    1996-03-01

    The hand-printed address recognition system described in this paper is a part of the Name and Address Block Reader (NABR) system developed by the Center of Excellence for Document Analysis and Recognition (CEDAR). NABR is currently being used by the IRS to read address blocks (hand-print as well as machine-print) on fifteen different tax forms. Although machine- print address reading was relatively straightforward, hand-print address recognition has posed some special challenges due to demands on processing speed (with an expected throughput of 8450 forms/hour) and recognition accuracy. We discuss various subsystems involved in hand- printed address recognition, including word segmentation, word recognition, digit segmentation, and digit recognition. We also describe control strategies used to make effective use of these subsystems to maximize recognition accuracy. We present system performance on 931 address blocks in recognizing various fields, such as city, state, ZIP Code, street number and name, and personal names.

  16. Surface confined metallosupramolecular architectures: formation and scanning tunneling microscopy characterization.

    Li, Shan-Shan; Northrop, Brian H; Yuan, Qun-Hui; Wan, Li-Jun; Stang, Peter J

    2009-02-17

    Metallosupramolecular compounds have attracted a great deal of attention over the past two decades largely because of their unique, highly complex structural characteristics and their potential electronic, magnetic, optical, and catalytic properties. These molecules can be prepared with relative ease using coordination-driven self-assembly techniques. In particular, the use of electron-poor square-planar Pt(II) transition metals in conjunction with rigid, electron-rich pyridyl donors has enabled the spontaneous self-assembly of a rich library of 2D metallacyclic and 3D metallacage assemblies via the directional-bonding approach. With this progress in the preparation and characterization of metallosupramolecules, researchers have now turned their attention toward fully exploring and developing their materials properties. Assembling metallosupramolecular compounds on solid supports represents a vitally important step toward developing their materials properties. Surfaces provide a means of uniformly aligning and orienting these highly symmetric metallacycles and metallacages. This uniformity increases the level of coherence between molecules above that which can be achieved in the solution phase and provides a way to integrate adsorbed layers, or adlayers, into a solid-state materials setting. The dynamic nature of kinetically labile Pt(II)-N coordination bonds requires us to adjust deposition and imaging conditions to retain the assemblies' stability. Toward these aims, we have used scanning tunneling microscopy (STM) to image these adlayers and to understand the factors that govern surface self-assembly and the interactions that influence their structure and stability. This Account describes our efforts to deposit 2D rectangular and square metallacycles and 3D trigonal bipyramidal and chiral trigonal prism metallacages on highly oriented pyrolytic graphite (HOPG) and Au(111) substrates to give intact assemblies and ordered adlayers. We have investigated the effects

  17. Organization of Control Units with Operational Addressing

    Alexander A. Barkalov; Roman M. Babakov; Larysa A. Titarenko

    2012-01-01

    The using of operational addressing unit as the block of control unit is proposed. The new structure model of Moore finite-state machine with reduced hardware amount is developed. The generalized structure of operational addressing unit is suggested. An example of synthesis process for Moore finite-state machine with operational addressing unit is given. The analytical researches of proposed structure of control unit are executed.

  18. IP Address Management Principles and Practice

    Rooney, Timothy

    2010-01-01

    This book will be the first covering the subject of IP address management (IPAM). The practice of IPAM includes the application of network management disciplines to IP address space and associated network services, namely DHCP (Dynamic Host Configuration Protocol) and DNS (Domain Name System). The consequence of inaccurately configuring DHCP is that end users may not be able to obtain IP addresses to access the network. Without proper DNS configuration, usability of the network will greatly suffer as the name-to-address lookup process may fail. Imagine having to navigate to a website or send a

  19. The effect of the adsorbate layer on the work function reduction of gold substrates under external electric fields

    He, Xiang; Cheng, Feng; Chen, Zhao-Xu

    2017-12-01

    The interface interaction between the dimethyl sulfide (DMS) molecule and the gold substrate under external electric fields is investigated by density functional theory method. The polarized DMS adsorbate reduces the work function of the gold substrate while the induced substrate dipole upon the adsorption slightly increases the work function. The DMS layer partially shields the Au(111) substrate from the electric fields and the vacuum level of DMS/Au(111) shifts less than of Au(111) in consequence. Under electric fields pointing outward from the Au(111) surface, both the reduction of work function and the adsorption of DMS molecule are enhanced on the surface. We also suggest the possible application of the field-effect transistor (FET) sensor with gold gate for detecting DMS molecule by utilizing the reduction of substrate work function upon adsorption. The effects of coverage and electric field on the theoretical sensitivity of the sensor are also discussed.

  20. Model non-equilibrium molecular dynamics simulations of heat transfer from a hot gold surface to an alkylthiolate self-assembled monolayer.

    Zhang, Yue; Barnes, George L; Yan, Tianying; Hase, William L

    2010-05-07

    Model non-equilibrium molecular dynamics (MD) simulations are presented of heat transfer from a hot Au {111} substrate to an alkylthiolate self-assembled monolayer (H-SAM) to assist in obtaining an atomic-level understanding of experiments by Wang et al. (Z. Wang, J. A. Carter, A. Lagutchev, Y. K. Koh, N.-H. Seong, D. G. Cahill, and D. D. Dlott, Science, 2007, 317, 787). Different models are considered to determine how they affect the heat transfer dynamics. They include temperature equilibrated (TE) and temperature gradient (TG) thermostat models for the Au(s) surface, and soft and stiff S/Au(s) models for bonding of the S-atoms to the Au(s) surface. A detailed analysis of the non-equilibrium heat transfer at the heterogeneous interface is presented. There is a short time temperature gradient within the top layers of the Au(s) surface. The S-atoms heat rapidly, much faster than do the C-atoms in the alkylthiolate chains. A high thermal conductivity in the H-SAM, perpendicular to the interface, results in nearly identical temperatures for the CH(2) and CH(3) groups versus time. Thermal-induced disorder is analyzed for the Au(s) substrate, the S/Au(s) interface and the H-SAM. Before heat transfer occurs from the hot Au(s) substrate to the H-SAM, there is disorder at the S/Au(s) interface and within the alkylthiolate chains arising from heat-induced disorder near the surface of hot Au(s). The short-time rapid heating of the S-atoms enhances this disorder. The increasing disorder of H-SAM chains with time results from both disorder at the Au/S interface and heat transfer to the H-SAM chains.

  1. A New Method of Chinese Address Extraction Based on Address Tree Model

    KANG Mengjun

    2015-01-01

    Full Text Available Address is a spatial location encoding method of individual geographical area. In China, address planning is relatively backward due to the rapid development of the city, resulting in the presence of large number of non-standard address. The space constrain relationship of standard address model is analyzed in this paper and a new method of standard address extraction based on the tree model is proposed, which regards topological relationship as consistent criteria of space constraints. With this method, standard address can be extracted and errors can be excluded from non-standard address. Results indicate that higher math rate can be obtained with this method.

  2. Generative Street Addresses from Satellite Imagery

    İlke Demir

    2018-03-01

    Full Text Available We describe our automatic generative algorithm to create street addresses from satellite images by learning and labeling roads, regions, and address cells. Currently, 75% of the world’s roads lack adequate street addressing systems. Recent geocoding initiatives tend to convert pure latitude and longitude information into a memorable form for unknown areas. However, settlements are identified by streets, and such addressing schemes are not coherent with the road topology. Instead, we propose a generative address design that maps the globe in accordance with streets. Our algorithm starts with extracting roads from satellite imagery by utilizing deep learning. Then, it uniquely labels the regions, roads, and structures using some graph- and proximity-based algorithms. We also extend our addressing scheme to (i cover inaccessible areas following similar design principles; (ii be inclusive and flexible for changes on the ground; and (iii lead as a pioneer for a unified street-based global geodatabase. We present our results on an example of a developed city and multiple undeveloped cities. We also compare productivity on the basis of current ad hoc and new complete addresses. We conclude by contrasting our generative addresses to current industrial and open solutions.

  3. Forms of Address in Chilean Spanish

    Bishop, Kelley; Michnowicz, Jim

    2010-01-01

    The present investigation examines possible social and linguistic factors that influence forms of address used in Chilean Spanish with various interlocutors. A characteristic of the Spanish of Chile is the use of a variety of forms of address for the second person singular, "tu", "vos", and "usted", with corresponding…

  4. 29 CFR 4245.7 - PBGC address.

    2010-07-01

    ... 29 Labor 9 2010-07-01 2010-07-01 false PBGC address. 4245.7 Section 4245.7 Labor Regulations Relating to Labor (Continued) PENSION BENEFIT GUARANTY CORPORATION INSOLVENCY, REORGANIZATION, TERMINATION, AND OTHER RULES APPLICABLE TO MULTIEMPLOYER PLANS NOTICE OF INSOLVENCY § 4245.7 PBGC address. See...

  5. Characterization and methanol electrooxidation studies of Pt(111)/Os surfaces prepared by spontaneous deposition.

    Johnston, Christina M; Strbac, Svetlana; Lewera, Adam; Sibert, Eric; Wieckowski, Andrzej

    2006-09-12

    Catalytic activity of the Pt(111)/Os surface toward methanol electrooxidation was optimized by exploring a wide range of Os coverage. Various methods of surface analyses were used, including electroanalytical, STM, and XPS methods. The Pt(111) surface was decorated with nanosized Os islands by spontaneous deposition, and the Os coverage was controlled by changing the exposure time to the Os-containing electrolyte. The structure of Os deposits on Pt(111) was characterized and quantified by in situ STM and stripping voltammetry. We found that the optimal Os surface coverage of Pt(111) for methanol electrooxidation was 0.7 +/- 0.1 ML, close to 1.0 +/- 0.1 Os packing density. Apparently, the high osmium coverage Pt(111)/Os surface provides more of the necessary oxygen-containing species (e.g., Os-OH) for effective methanol electrooxidation than the Pt(111)/Os surfaces with lower Os coverage (vs e.g., Ru-OH). Supporting evidence for this conjecture comes from the CO electrooxidation data, which show that the onset potential for CO stripping is lowered from 0.53 to 0.45 V when the Os coverage is increased from 0.2 to 0.7 ML. However, the activity of Pt(111)/Os for methanol electrooxidation decreases when the Os coverage is higher than 0.7 +/- 0.1 ML, indicating that Pt sites uncovered by Os are necessary for sustaining significant methanol oxidation rates. Furthermore, osmium is inactive for methanol electrooxidation when the platinum substrate is absent: Os deposits on Au(111), a bulk Os ingot, and thick films of electrodeposited Os on Pt(111), all compare poorly to Pt(111)/Os. We conclude that a bifunctional mechanism applies to the methanol electrooxidation similarly to Pt(111)/Ru, although with fewer available Pt sites. Finally, the potential window for methanol electrooxidation on Pt(111)/Os was observed to shift positively versus Pt(111)/Ru. Because of the difference in the Os and Ru oxophilicity under electrochemical conditions, the Os deposit provides fewer

  6. Moving to world's best uranium address

    Noakes, Frank

    2006-01-01

    Most exploration dollars spent in South Australia are focused on exploiting uranium. This is for good reason as South Australia is the world's best address for uranium. Pressure to cut CO 2 emissions and the ballistic growth of the Chinese and Indian economies has heightened expectations that the worldwide use of uranium for power generation will mushroom beyond its current 17% market share. The recent Australia-China deal only seems to confirm this; hence uranium's growing popularity among miners and explorers. Such is the attractiveness of uranium-related floats, when Toro Energy sought $18m in March it was swamped with more than three times share application volume. In the north west, Southern Gold and Hindmarsh Resources are expectantly drilling for commercial uranium deposits all around the acreage that hosts the Challenger gold mine in the Gawler Craton. The first exploration drilling for uranium in quaternary-age river channels will take place in South Australia's far north in May. Red Metal says while older and deeper tertiary river channels in the area that host the Beverley uranium mine were explored for uranium, the younger near-surface channel has not had a single hole drilled for uranium. This is despite the area being one of the 'hottest radiogenic terrains in South Australia'. The company will target calcrete-style uranium mineralisation similar to the Yerrlirrie deposit in Western Australia (52,000t U308). Tasman Resources will start drilling to test seven uranium targets within 30km of Olympic Dam, the world's largest known uranium deposit, later this year. Tasman also holds tenements adjoining the Warrior uranium deposit near Tarcoola that contains known radiometric anomalies within the 40km-long Wynbring paleochannels. They are the fourth largest uranium explorer in South Australia. Alliance Resources and its JV partner Quasar Resources are exploring the Beverley 4 Mile uranium prospect at Arkaroola. Quasar is an affiliate of Heathgate Resources

  7. Local address and emergency contact details

    2013-01-01

    The HR Department would like to remind members of the personnel that they are responsible for ensuring that their personal data concerning local address and preferred emergency contact details remains valid and up-to-date.   Both are easily accessible via the links below: Local address: https://edh.cern.ch/Document/Personnel/LocalAddressChange   Emergency contacts: https://edh.cern.ch/Document/Personnel/EC   Please take a few minutes to check your details and modify if necessary. Thank you in advance. HR Department Head Office

  8. Radiation and occupational health: opening address

    Mohammad Taib Osman

    1995-01-01

    The part of address discusses the following issue: benefits of radiological protection in Malaysia, traceability and accountability as assurance of the validity of radiation measurement, Laboratory Accreditation Scheme, Atomic Energy Licensing Act

  9. VT E911 ESITE geocoder - address points

    Vermont Center for Geographic Information — VT E911 ESITE geocoder - address points. VCGI, in collaboration with the VT E911 Board, has created a suite of geocoding services that can be used to batch geocode...

  10. What is an address in South Africa?

    Coetzee, S

    2007-11-01

    Full Text Available Puccini Street, Constantia Park 546 Puccini Street, Glenstantia, 0181 A recent study in Denmark analysed the qualitative and quantitative impact of address ambiguities. The qualitative analysis confirmed that the ambiguities affect people every day... description consists of a land parcel number together with a registered name and registration division, and is recorded at a Surveyor-General’s office. An address complements a land parcel description with information such as the street name and the street...

  11. Research Note Consumer Addressability and Customized Pricing

    Yuxin Chen; Ganesh Iyer

    2002-01-01

    The increasing availability of customer information is giving many firms the ability to reach and customize price and other marketing efforts to the tastes of the individual consumer. This ability is labeled as consumer addressability. Consumer addressability through sophisticated databases is particularly important for direct-marketing firms, catalog retailers such as L.L Bean and Land's End, credit card-issuing banks, and firms in the long-distance telephone market. We examine the strategic...

  12. South African address standard and initiatives towards an international address standard

    Cooper, Antony K

    2008-10-01

    Full Text Available ; visiting friends; and providing a reference context for presenting other information. The benefits of an international address standards include: enabling address interoperability across boundaries; reducing service delivery costs; enabling development...

  13. Enter your email-address: how German internet users manage their email addresses

    Utz, S.

    2004-01-01

    Writing E-mail is the most popular Internet activity. Meanwhile, many people have more than one E-mail address. The question how people manage their E-mail addresses, more specifically, whether they use them deliberately for different purposes, is the central question of this paper. E-mail addresses

  14. EDITORIAL: From reciprocal space to real space in surface science From reciprocal space to real space in surface science

    Bartels, Ludwig; Ernst, Karl-Heinz

    2012-09-01

    Triest.let's finish—aus basta Some move atoms around to hear how they sound.Karl-Heinz Rieder, Erice, 6 April 1998 From reciprocal space to real space in surface science contents From reciprocal space to real space in surface scienceLudwig Bartels and Karl-Heinz Ernst Karl-Heinz Reider: the quiet pioneerGiorgio Benedek Scattering of CO and N2 molecules by a graphite surfaceJunepyo Oh, Takahiro Kondo, Keitaro Arakawa, Yoshihiko Saito, Junji Nakamura, W W Hayes and J R Manson Helium, neon and argon diffraction from Ru(0001)M Minniti, C Díaz, J L Fernández Cuñado, A Politano, D Maccariello, F Martín, D Farías and R Miranda Enhanced charge transfer in a monolayer of the organic charge transfer complex TTF-TNAP on Au(111)T R Umbach, I Fernandez-Torrente, J N Ladenthin, J I Pascual and K J Franke Extended pattern recognition scheme for self-learning kinetic Monte Carlo simulationsSyed Islamuddin Shah, Giridhar Nandipati, Abdelkader Kara and Talat S Rahman Acetylene on Cu(111): imaging a molecular surface arrangement with a constantly rearranging tipYeming Zhu, Jonathan Wyrick, Kamelia D Cohen, Katie Marie Magnone, Connor Holzke, Daniel Salib, Quan Ma, Dezheng Sun and Ludwig Bartels Coulomb attraction during the carpet growth mode of NaClFriederike Matthaei, Sarah Heidorn, Konrad Boom, Cord Bertram, Ali Safiei, Jörg Henzl and Karina Morgenstern Molecular self-assembly on an insulating surface: interplay between substrate templating and intermolecular interactionsMarkus Kittelmann, Philipp Rahe and Angelika Kühnle Vertical manipulation of native adatoms on the InAs(111)A surfaceJ Yang, C Nacci, J Martínez-Blanco, K Kanisawa and S Fölsch Charge transfer between isomer domains on n+-doped Si(111)-2 × 1: energetic stabilizationR M Feenstra, G Bussetti, B Bonanni, A Violante, C Goletti, P Chiaradia, M G Betti and C Mariani Probing the properties of metal-oxide interfaces: silica films on Mo and Ru supportsLeonid Lichtenstein, Markus Heyde, Stefan Ulrich, Niklas Nilius

  15. Addressing the Issue: Bullying and LGBTQ Youth

    Kimberly Allen

    2014-09-01

    Full Text Available Each day, thousands of youth experience bullying and as many of 70% of all youth report having experienced bullying, either directly or indirectly (Cantor, 2005. For Gay, Lesbian, Bi-sexual, Transgender and Questioning (LGBTQ youth, the chances of experiencing bullying are much higher than for youth in the general population (Russell, Horn, Kosciw, & Saewyc, 2010. Although many youth serving organizations have begun to address the issue of bullying with bullying prevention programs, there is a deficit of information and a lack of inclusion of prevention efforts that specifically address LGBTQ youth. This article address the role of youth organizations in creating safe and inclusive environments for all youth, with specific attention paid to resources and strategies for inclusive environments for LGBTQ youth.

  16. Centrally managed unified shared virtual address space

    Wilkes, John

    2018-02-13

    Systems, apparatuses, and methods for managing a unified shared virtual address space. A host may execute system software and manage a plurality of nodes coupled to the host. The host may send work tasks to the nodes, and for each node, the host may externally manage the node's view of the system's virtual address space. Each node may have a central processing unit (CPU) style memory management unit (MMU) with an internal translation lookaside buffer (TLB). In one embodiment, the host may be coupled to a given node via an input/output memory management unit (IOMMU) interface, where the IOMMU frontend interface shares the TLB with the given node's MMU. In another embodiment, the host may control the given node's view of virtual address space via memory-mapped control registers.

  17. Address rituals as heuristics of social structure

    E.F. Kotze

    2013-02-01

    Full Text Available The address form as linguistic variable has more realisation possibilities than any other, because semantic variation is involved and it reflects all the different interpersonal relations in the societal structure. Factors such as religious status, sex, kinship and age differences play a key role in the choice of the address form. It is hypothesised that the way in which address forms vary in a speech community is a linguistic reflection of the social norms determining the hierarchical structure of the community. Die aanspreekvorm as linguistiese veranderlike het meer verwesenlikingsmoontlikhede as enige ander vorm, want semantiese verskeidenheid is betrokke en dit reflekteer die verskillende interpersoonlike verhoudings in die gemeenskapstruktuur. Faktore soos religieuse status, geslag, verwantskap en ouderdomsverskille speel 'n sleutelrol in die aanspreekvorm. Daar word gehipotetiseer dat die wyse waarop aanspreekvorms in 'n spraakgemeenskap wissel, 'n linguistiese refleksie is van die sosiale norme wat die hierargiese struktuur van die gemeenskap bepaal.

  18. Centrally managed unified shared virtual address space

    Wilkes, John

    2018-02-13

    Systems, apparatuses, and methods for managing a unified shared virtual address space. A host may execute system software and manage a plurality of nodes coupled to the host. The host may send work tasks to the nodes, and for each node, the host may externally manage the node's view of the system's virtual address space. Each node may have a central processing unit (CPU) style memory management unit (MMU) with an internal translation lookaside buffer (TLB). In one embodiment, the host may be coupled to a given node via an input/output memory management unit (IOMMU) interface, where the IOMMU frontend interface shares the TLB with the given node's MMU. In another embodiment, the host may control the given node's view of virtual address space via memory-mapped control registers.

  19. What Type of Knowledge Provides Valid Housing Standards Addressing Accessibility?

    Helle, Tina; Brandt, Åse; Iwarsson, Susanne

    evaluations of task-surface heights in elderly people’s homes. Applied Ergonomics, 31, 109-119. Kohlbacher, F. (2006). The use of qualitative content analysis in case study research. Forum: Qualitative social research sozialforschung (FQS), Open Journal Systems, vol 7, No1. Kozey, J.W. & Das, B. (2004...... accessibility aspects such as either reach, seat height or space requirements • Targeted primarily industrial workstation design and only wheelchair/scooter users • Addressed positions (standing/seated) and sex difference with respect to reach • Was generated in lab-like environments, using methods...... of the validity of housing standards. Therefore, it is reasonable to question what type of knowledge that provides the most valid standards addressing accessibility and explore the consequences of using an alternative approach. The idea was thus to examine the validity of a set of housing standards using a so...

  20. Content addressable memories in scientific instruments

    Lotto, I. de; Golinelli, S.

    1975-01-01

    The content-addressable-memory feature of a new system designed in these laboratories for non-destructive testing of nuclear reactor pressure vessels based on acoustic emission analysis is presented. The content addressable memory is divided into two parts: the first selects the most frequent events among incoming ones (FES: Frequent Event Selection memory), the second stores the frequent events singled out (FEM: Frequent Event Memory). The statistical behaviour of FES is analyzed, and experimental results are compared with theoretical ones; the model presented proved to be a useful tool in dimensioning the instrument store capacity. (Auth.)

  1. ADDRESS SEQUENCES FOR MULTI RUN RAM TESTING

    V. N. Yarmolik

    2014-01-01

    Full Text Available A universal approach for generation of address sequences with specified properties is proposed and analyzed. A modified version of the Antonov and Saleev algorithm for Sobol sequences genera-tion is chosen as a mathematical description of the proposed method. Within the framework of the proposed universal approach, the Sobol sequences form a subset of the address sequences. Other sub-sets are also formed, which are Gray sequences, anti-Gray sequences, counter sequences and sequenc-es with specified properties.

  2. World Federation of Vascular Societies: presidential address

    Sillesen, Henrik Hegaard

    2010-01-01

    The presidential address describes briefly the history of the World Federation for Vascular Societies (WFVS) and its objectives. Vascular Surgery today includes interventional procedures (open surgical and endovascular) in addition to risk factor reduction and medical treatment. It is equally imp...... throughout the world. In addition, for introduction of new treatments, training issues and dissemination of science a global organisation like the WFVS is needed.......The presidential address describes briefly the history of the World Federation for Vascular Societies (WFVS) and its objectives. Vascular Surgery today includes interventional procedures (open surgical and endovascular) in addition to risk factor reduction and medical treatment. It is equally...

  3. Addressing techniques of liquid crystal displays

    Ruckmongathan, Temkar N

    2014-01-01

    Unique reference source that can be used from the beginning to end of a design project to aid choosing an appropriate LCD addressing technique for a given application This book will be aimed at design engineers who are likely to embed LCD drivers and controllers in many systems including systems on chip. Such designers face the challenge of making the right choice of an addressing technique that will serve them with best performance at minimal cost and complexity. Readers will be able to learn about various methods available for driving matrix LCDs and the comparisons at the end of each chap

  4. Surface Water & Surface Drainage

    Earth Data Analysis Center, University of New Mexico — This data set contains boundaries for all surface water and surface drainage for the state of New Mexico. It is in a vector digital data structure digitized from a...

  5. ADDRESSING THE RISKS OF GLOBAL PRODUCT DEVELOPMENT

    Hansen, Zaza Nadja Lee; Ahmed-Kristensen, Saeema

    2011-01-01

    to rework, misunderstandings, miscommunication and lower quality. This paper investigates how the organisation can reduce the negative aspects of offshoring by presenting two possible approaches; one which lessens the exposure to situations in which these negative impacts happen and another which addresses...

  6. Addressing Diversity: A Call for Action.

    Henderson, Ingeborg

    1991-01-01

    Suggests a series of steps that individuals in the foreign language profession can take to effectively address the issue of demographic changes in the U.S. college student populations and keeping foreign language learning a feasible discipline in the future. (26 references) (GLR)

  7. Road Map to Address Cognitive Health

    2014-06-09

    In this podcast, CDC’s Dr. Lynda Anderson highlights the important roles that states and communities can play in addressing cognitive health as part of overall health.  Created: 6/9/2014 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 6/9/2014.

  8. Addressing food waste reduction in Denmark

    Halloran, Afton Marina Szasz; Clement, Jesper; Kornum, Niels

    2014-01-01

    , improvements in technology have made it more efficient to utilize food waste for biogas and compost, which improves nutrient cycling through the food system. Major efforts to address food waste in Denmark have mainly been promoted through civil society groups with governmental support, as well as by industry...

  9. 40 CFR 65.14 - Addresses.

    2010-07-01

    ... 75202. Region VII (Iowa, Kansas, Missouri, Nebraska), Director, Air and Toxics Division, U.S. Environmental Protection Agency, 726 Minnesota Avenue, Kansas City, Kansas 66101. Region VIII (Colorado, Montana... authority has been delegated under section 112(l) of the Act. The mailing addresses for State agencies are...

  10. Addressing the Global Burden of Breast Cancer

    The US National Cancer Institute’s Center for Global Health (CGH) has been a key partner in a multi-institutional expert team that has developed a set of publications to address foundational concerns in breast cancer care across the cancer care continuum and within limited resource settings.

  11. Addressing production stops in the food industry

    Hansen, Zaza Nadja Lee; Herbert, Luke Thomas; Jacobsen, Peter

    2014-01-01

    This paper investigates the challenges in the food industry which causes the production lines to stop, illustrated by a case study of an SME size company in the baked goods sector in Denmark. The paper proposes key elements this sector needs to be aware of to effectively address production stops......, and gives examples of the unique challenges faced by the SME food industry....

  12. Rational Rhymes for Addressing Common Childhood Issues

    Warren, Jeffrey M.

    2011-01-01

    Music-based interventions are valuable tools counselors can use when working with children. Specific types of music-based interventions, such as songs or rhymes, can be especially pertinent in addressing the thoughts, feelings, and behaviors of children. Rational-emotive behavior therapy (REBT) provides a therapeutic framework that encourages…

  13. 76 FR 80903 - Mandatory Declassification Review Addresses

    2011-12-27

    ... John J. Kingman Road, Fort Belvoir, VA 22060-6201. (13) Missile Defense Agency. Missile Defense Agency... DEPARTMENT OF DEFENSE Office of the Secretary Mandatory Declassification Review Addresses AGENCY: Department of Defense. ACTION: Notice. SUMMARY: Pursuant to the Information Security Oversight Office's...

  14. Addressing Student Debt in the Classroom

    Perkins, David; Johnston, Tim; Lytle, Rick

    2016-01-01

    Student debt is a national concern. The authors address debt in the classroom to enhance students' understanding of the consequences of debt and the need for caution when financing their education. However, student feedback indicates this understanding has a delayed effect on borrowing behavior and underscores the importance of making difficult…

  15. 37 CFR 301.2 - Official addresses.

    2010-07-01

    ..., Room LM-401 in the James Madison Memorial Building, Monday through Friday, between 8:30 a.m. and 5 p.m., and be addressed as follows: Copyright Royalty Board, Library of Congress, James Madison Memorial... Royalty Board, Library of Congress, James Madison Memorial Building, 101 Independence Avenue, SE...

  16. Registering Names and Addresses for Information Technology.

    Knapp, Arthur A.

    The identification of administrative authorities and the development of associated procedures for registering and accessing names and addresses of communications data systems are considered in this paper. It is noted that, for data communications systems using standards based on the Open Systems Interconnection (OSI) Reference Model specified by…

  17. Addressing Measurement Issues Related to Bullying Involvement

    Casper, Deborah M.; Meter, Diana J.; Card, Noel A.

    2015-01-01

    In this article, we address measurement issues related to select aspects of bullying involvement with the goal of moving psychometrically sound measurement practices toward applied bullying research. We first provide a nontechnical introduction to psychometric considerations in measuring bullying involvement, highlighting the importance of…

  18. Volume 1: president's address, CNA committee reports

    The president's address summarizes the 1974-75 activities of the CNA and reports are given by CNA subcommittees on codes, standards and practices, economic development, education and manpower, international affairs, nuclear insurance, nuclear safety and environment, public relations, and technology. (E.C.B.)

  19. How Sociology Texts Address Gun Control

    Tonso, William R.

    2004-01-01

    William R. Tonso has chosen an issue that he knows something about to examine how sociology textbooks address controversy. Appealing for gun control is fashionable, but it is at odds with a fondness that ordinary Americans have for their firearms--one that is supported by a growing body of research on deterrence to crime. There are two sides to…

  20. Transition through Teamwork: Professionals Address Student Access

    Bube, Sue Ann; Carrothers, Carol; Johnson, Cinda

    2016-01-01

    Prior to 2013, there was no collaboration around the transition services for deaf and hard of hearing students in Washington State. Washington had numerous agencies providing excellent support, but those agencies were not working together. It was not until January 29, 2013, when pepnet 2 hosted the Building State Capacity to Address Critical…

  1. Addressing Sexual Violence as Student Affairs Work

    Landreman, Lisa M.; Williamsen, Kaaren M.

    2018-01-01

    In this chapter, we outline the challenges campuses face in addressing sexual violence and Title IX compliance. We argue that there are critical roles for student affairs professionals in Title IX work in developing effective campus sexual violence prevention and response strategies.

  2. Programming chemistry in DNA-addressable bioreactors

    Fellermann, H.; Cardelli, L.

    2014-01-01

    . These markers serve as compartment addresses and allow for their targeted transport and fusion, thereby enabling reactions of previously separated chemicals. The overall system organization allows for the set-up of programmable chemistry in microfluidic or other automated environments. We introduce a simple...

  3. THE ROLE OF NUTRITIONAL INFORMATION IN ADDRESSING ...

    The paper discusses the role of nutritional information for addressing under-five child malnutrition in Tanzania. The paper is based on a master's dissertation whose objective was to determine the sources of nutritional information used to provide nutritional information to mothers in Maternal and Child Health (MCH) clinics, ...

  4. Robust Decision Making: Addressing Uncertainties in Distributions

    Uryasev, Stanislav

    2004-01-01

    .... The model considered aircraft trajectory in three-dimensional space. Several threats were studied, including risk of aircraft detection by radars, sensors, and the risk of being killed by surface to air missiles...

  5. Image Coding Based on Address Vector Quantization.

    Feng, Yushu

    Image coding is finding increased application in teleconferencing, archiving, and remote sensing. This thesis investigates the potential of Vector Quantization (VQ), a relatively new source coding technique, for compression of monochromatic and color images. Extensions of the Vector Quantization technique to the Address Vector Quantization method have been investigated. In Vector Quantization, the image data to be encoded are first processed to yield a set of vectors. A codeword from the codebook which best matches the input image vector is then selected. Compression is achieved by replacing the image vector with the index of the code-word which produced the best match, the index is sent to the channel. Reconstruction of the image is done by using a table lookup technique, where the label is simply used as an address for a table containing the representative vectors. A code-book of representative vectors (codewords) is generated using an iterative clustering algorithm such as K-means, or the generalized Lloyd algorithm. A review of different Vector Quantization techniques are given in chapter 1. Chapter 2 gives an overview of codebook design methods including the Kohonen neural network to design codebook. During the encoding process, the correlation of the address is considered and Address Vector Quantization is developed for color image and monochrome image coding. Address VQ which includes static and dynamic processes is introduced in chapter 3. In order to overcome the problems in Hierarchical VQ, Multi-layer Address Vector Quantization is proposed in chapter 4. This approach gives the same performance as that of the normal VQ scheme but the bit rate is about 1/2 to 1/3 as that of the normal VQ method. In chapter 5, a Dynamic Finite State VQ based on a probability transition matrix to select the best subcodebook to encode the image is developed. In chapter 6, a new adaptive vector quantization scheme, suitable for color video coding, called "A Self -Organizing

  6. Forms of Address as Discrete Modal Operators

    Wojciech Paweł Sosnowski

    2016-12-01

    Full Text Available Forms of Address as Discrete Modal Operators The category of expressions of politeness includes, among others, forms of address. Forms of address express honorification. Honorification can be defined as a special type of meaning that consists of information about the social and interpersonal relations between the speaker and the addressee, the speaker and the hearer, and the speaker and the protagonist of the predication. As far as their place in the syntactic structure is concerned, forms of address can either be integrated with the other elements of a predication or not. However, they are always part of a predication’s semantic structure. Moreover, forms of address convey the speaker’s attitude to the meaning of the predicate that they want to convey, which consequently means that forms of address also carry a modal element. Modality can be defined as a situation in which an individual is in a particular mental state, i.e. exhibits some kind of attitude to a situation or a type of situations. Forms of address can be categorised as modal operators conveying imperatives, requests, suppositions, etc. The term "operator" can be used for a unit of language when it changes the semantic structure of the predication. My research on honorification is mainly based on contemporary corpora, both monolingual and multilingual. In the present study, I analyse forms of address which carry imperative and optative meanings.   Formy adresatywne jako dyskretne operatory modalne W obrębie wyrażeń realizujących funkcje grzecznościowe znajduje się grupa form adresatywnych. Są one częścią kategorii honoryfikatywności rozumianej jako szczególny rodzaj znaczenia zawartego w treści wypowiedzi, informację o towarzysko-społecznej relacji między nadawcą a odbiorcą, nadawcą a słuchaczem oraz nadawcą a bohaterem wypowiedzi. Gramatycznie formy adresatywne mogą być zarówno zintegrowane, jak i niezintegrowane syntaktycznie z resztą wypowiedzi, ale

  7. Addressing mixed waste in plutonium processing

    Christensen, D.C.; Sohn, C.L.; Reid, R.A.

    1991-01-01

    The overall goal is the minimization of all waste generated in actinide processing facilities. Current emphasis is directed toward reducing and managing mixed waste in plutonium processing facilities. More specifically, the focus is on prioritizing plutonium processing technologies for development that will address major problems in mixed waste management. A five step methodological approach to identify, analyze, solve, and initiate corrective action for mixed waste problems in plutonium processing facilities has been developed

  8. Do pediatric gastroenterology doctors address pediatric obesity?

    Batra, Suruchi; Yee, Caitlin; Diez, Bernadette; Nguyen, Nicholas; Sheridan, Michael J; Tufano, Mark; Sikka, Natalie; Townsend, Stacie; Hourigan, Suchitra

    2017-01-01

    Objectives: To assess how often obesity is acknowledged at pediatric gastroenterology outpatient visits. Methods: A retrospective chart review was performed to identify obese children seen at a gastroenterology subspecialty clinic over a 1-year period of time; 132 children were identified. Demographics, obesity comorbidities, reasons for referral, diagnosis of obesity, and a plan to address obesity were abstracted. Chi-square or Fisher?s exact tests were used to examine statistical associatio...

  9. Forest Policies Addressing Climate Change in China

    2010-01-01

    As a developing country with a large population and a fragile ecological environment, China is particularly vulnerable to the adverse effects of climate change. Beginning with the Rio Conference of 1992 China has played a progressively enhanced role in combating climate change. A series of policies and measures to address climate change have been taken in the overall context of national sustainable development strategy, making positive contributions to the mitigation and adaptation to climate change, among ...

  10. Opening address; Allocution d`ouverture

    Carle, R

    1996-12-31

    In this opening address the president of WANO underlines the relative isolation of the Kozloduy NPP from the international nuclear community due to the lack of information and contacts. The need for eliminating the isolation is stressed and the following measures are proposed: to make the Kozloduy NPP an active member of the international community; to improve and maintain the safety level; to contribute to the electricity exchange system of Southeastern Europe.

  11. Addressing consumerization of IT risks with nudging

    Iryna Yevseyeva; James Turland; Charles Morisset; Lynne Coventry; Thomas Groß

    2015-01-01

    In this work we address the main issues of Information Technology (IT) consumerisation that are related to security risks, and vulnerabilities of devices used within Bring Your Own Device (BYOD) strategy in particular. We propose a ‘soft’ mitigation strategy for user actions based on nudging, widely applied to health and social behaviour influence. In particular, we propose a complementary, less strict, more flexible Information Security policies, based on risk assessment of device vulnerabil...

  12. Activities to Address Challenges in Digital Innovation

    Lund , Jesper

    2014-01-01

    Part 3: Structures and Networks; International audience; Based on a literature review, this paper identifies four socio-technical challenges relating to innovation actor’s interactions in digital innovation. Furthermore, the paper explores how these challenges can be addressed. The challenges are investigated in a case study of digital innovation. The study is based on a two year long research and development project where an e-newspaper concept and a demonstrator based on e-paper technology ...

  13. Overview of an address and purpose of the workshop [ISO Workshop on address standards: Considering the issues related to an international address standard

    Cooper, Antony K

    2008-05-01

    Full Text Available ) (ISO 19112) Precision Redirectable Standards Postal address Street delivery address Y N N Y N Y Fine Y UPU S42 PO Box or Private Bag Y N N Y Fine to Coarse Y UPU S42 Post Restante Y N N Y N Y Coarse Y UPU S42 Delivery address... (for goods, etc) Street address Y N N Y N Y Fine N Intersection address Y N N Y N Y Fine N Landmark address Y N N Y N Y Fine to Moderate N Building address Y N N Y N Y Fine N Site address Y N N Y N Y Fine to Coarse N Farm...

  14. MATCHING ALTERNATIVE ADDRESSES: A SEMANTIC WEB APPROACH

    S. Ariannamazi

    2015-12-01

    Full Text Available Rapid development of crowd-sourcing or volunteered geographic information (VGI provides opportunities for authoritatives that deal with geospatial information. Heterogeneity of multiple data sources and inconsistency of data types is a key characteristics of VGI datasets. The expansion of cities resulted in the growing number of POIs in the OpenStreetMap, a well-known VGI source, which causes the datasets to outdate in short periods of time. These changes made to spatial and aspatial attributes of features such as names and addresses might cause confusion or ambiguity in the processes that require feature’s literal information like addressing and geocoding. VGI sources neither will conform specific vocabularies nor will remain in a specific schema for a long period of time. As a result, the integration of VGI sources is crucial and inevitable in order to avoid duplication and the waste of resources. Information integration can be used to match features and qualify different annotation alternatives for disambiguation. This study enhances the search capabilities of geospatial tools with applications able to understand user terminology to pursuit an efficient way for finding desired results. Semantic web is a capable tool for developing technologies that deal with lexical and numerical calculations and estimations. There are a vast amount of literal-spatial data representing the capability of linguistic information in knowledge modeling, but these resources need to be harmonized based on Semantic Web standards. The process of making addresses homogenous generates a helpful tool based on spatial data integration and lexical annotation matching and disambiguating.

  15. Best Practices in Hiring: Addressing Unconscious Bias

    Simpson, Caroline E.

    2012-01-01

    Research has shown that implementing certain hiring practices will increase diversity in the workplace while enhancing academic quality. All of these practices rely on addressing the issue of 'unconscious bias.' A brief overview of unconscious bias--what it is, how it works, and simple measures to counter it--will be presented. Successful strategies, actions, and recommendations for implementing best recruiting and hiring practices, which have been proven to enhance academic excellence by ensuring a deep and diverse applicant pool, will also be presented.

  16. Building technology services that address student needs.

    Le Ber, Jeanne M; Lombardo, Nancy T; Wimmer, Erin

    2015-01-01

    A 16-question technology use survey was conducted to assess incoming health sciences students' knowledge of and interest in current technologies, and to identify student device and tool preferences. Survey questions were developed by colleagues at a peer institution and then edited to match this library's student population. Two years of student responses have been compiled, compared, and reviewed as a means for informing library decisions related to technology and resource purchases. Instruction and event programming have been revised to meet student preferences. Based on the number of students using Apple products, librarians are addressing the need to become more proficient with this platform.

  17. HEP technologies to address medical imaging challenges

    CERN. Geneva

    2016-01-01

    Developments in detector technologies aimed at solving challenges in present and future CERN experiments, particularly at the LHC, have triggered exceptional advances in the performance of medical imaging devices, allowing for a spectacular progress in in-vivo molecular imaging procedures, which are opening the way for tailored therapies of major diseases. This talk will briefly review the recent history of this prime example of technology transfer from HEP experiments to society, will describe the technical challenges being addressed by some ongoing projects, and will present a few new ideas for further developments and their foreseeable impact.

  18. Addressing Circuitous Currents MVDC Power Systems Protection

    2017-12-31

    Addressing Circuitous Currents MVDC Power Systems Protection 5b. GRANT NUMBER N00014-16-1-3113 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR($) Sd. PROJECT NUMBER...efficiency. A challenge with DC distribution is electrical protection . Z-source DC breakers alt! an pti n b&i g cvr.sidcrcd and this w rk ~xplores...zonal distribution, electric ship 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF a. REPORT b. ABSTRACT c. THIS PAGE ABSTRACT u u u uu 18. NUMBER

  19. Validation of Housing Standards Addressing Accessibility

    Helle, Tina

    2013-01-01

    The aim was to explore the use of an activity-based approach to determine the validity of a set of housing standards addressing accessibility. This included examination of the frequency and the extent of accessibility problems among older people with physical functional limitations who used...... participant groups were examined. Performing well-known kitchen activities was associated with accessibility problems for all three participant groups, in particular those using a wheelchair. The overall validity of the housing standards examined was poor. Observing older people interacting with realistic...... environments while performing real everyday activities seems to be an appropriate method for assessing accessibility problems....

  20. Addressing Longevity’ Heterogeneity in Pension Scheme Design

    Ayuso, Mercedes; Bravo, Jorge Miguel; Holzmann, Robert

    2017-01-01

    Ayuso, M., Bravo, J. M., & Holzmann, R. (2017). Addressing Longevity’ Heterogeneity in Pension Scheme Design. Journal of Finance and Economics, 6(1), 1-21. DOI: 10.12735/jfe.v6n1p1 This paper demonstrates that the link between heterogeneity in longevity and lifetime income across countries is mostly high and often increasing; that it translates into an implicit tax/subsidy, with rates reaching 20 percent and higher in some countries; that such rates risk perverting redistributive objective...

  1. Addressing firefighter safety around solar PV systems

    Harris, B. [Sustainable Energy Technologies, Calgary, AB (Canada)

    2010-11-15

    The article discussed new considerations for installing photovoltaic (PV) systems that address the needs of fire service personnel. The presence of a PV system presents a multitude of dangers for firefighters, including electrical shock, the inhalation of toxic gases from being unable to cut a hole through the roof, falling debris and flying glass, and dead loading on a compromised structure and tripping on conduits. Mapping systems should be modified so that buildings with PV systems are identified for first responders, including firefighters who should learn that solar modules present an electrical hazard during the day but not at night; covering PV modules with foam or salvage covers may not shut the system down to a safe level; it takes a few moments for the power in PV modules to reduce to zero; and PV modules or conduit should never be cut, broke, chopped, or walked upon. The California Department of Forestry and Fire Protection recommends creating pathways and allowing easier access to the roof by setting the modules back from roof edges, creating a structurally sound pathway for firefighters to walk on and space to cut ventilation holes. However, the setback rule makes the economics of solar installation less viable for residential applications. The technological innovations aimed at addressing system safety all focus on limiting firefighter contact with live electrical components to within the extra-low-voltage (ELV) band. Some of the inverters on the market that support ELV system architecture were described. 1 fig.

  2. Event generators for address event representation transmitters

    Serrano-Gotarredona, Rafael; Serrano-Gotarredona, Teresa; Linares Barranco, Bernabe

    2005-06-01

    Address Event Representation (AER) is an emergent neuromorphic interchip communication protocol that allows for real-time virtual massive connectivity between huge number neurons located on different chips. By exploiting high speed digital communication circuits (with nano-seconds timings), synaptic neural connections can be time multiplexed, while neural activity signals (with mili-seconds timings) are sampled at low frequencies. Also, neurons generate 'events' according to their activity levels. More active neurons generate more events per unit time, and access the interchip communication channel more frequently, while neurons with low activity consume less communication bandwidth. In a typical AER transmitter chip, there is an array of neurons that generate events. They send events to a peripheral circuitry (let's call it "AER Generator") that transforms those events to neurons coordinates (addresses) which are put sequentially on an interchip high speed digital bus. This bus includes a parallel multi-bit address word plus a Rqst (request) and Ack (acknowledge) handshaking signals for asynchronous data exchange. There have been two main approaches published in the literature for implementing such "AER Generator" circuits. They differ on the way of handling event collisions coming from the array of neurons. One approach is based on detecting and discarding collisions, while the other incorporates arbitration for sequencing colliding events . The first approach is supposed to be simpler and faster, while the second is able to handle much higher event traffic. In this article we will concentrate on the second arbiter-based approach. Boahen has been publishing several techniques for implementing and improving the arbiter based approach. Originally, he proposed an arbitration squeme by rows, followed by a column arbitration. In this scheme, while one neuron was selected by the arbiters to transmit his event out of the chip, the rest of neurons in the array were

  3. Addressing health literacy in patient decision aids

    2013-01-01

    Background Effective use of a patient decision aid (PtDA) can be affected by the user’s health literacy and the PtDA’s characteristics. Systematic reviews of the relevant literature can guide PtDA developers to attend to the health literacy needs of patients. The reviews reported here aimed to assess: 1. a) the effects of health literacy / numeracy on selected decision-making outcomes, and b) the effects of interventions designed to mitigate the influence of lower health literacy on decision-making outcomes, and 2. the extent to which existing PtDAs a) account for health literacy, and b) are tested in lower health literacy populations. Methods We reviewed literature for evidence relevant to these two aims. When high-quality systematic reviews existed, we summarized their evidence. When reviews were unavailable, we conducted our own systematic reviews. Results Aim 1: In an existing systematic review of PtDA trials, lower health literacy was associated with lower patient health knowledge (14 of 16 eligible studies). Fourteen studies reported practical design strategies to improve knowledge for lower health literacy patients. In our own systematic review, no studies reported on values clarity per se, but in 2 lower health literacy was related to higher decisional uncertainty and regret. Lower health literacy was associated with less desire for involvement in 3 studies, less question-asking in 2, and less patient-centered communication in 4 studies; its effects on other measures of patient involvement were mixed. Only one study assessed the effects of a health literacy intervention on outcomes; it showed that using video to improve the salience of health states reduced decisional uncertainty. Aim 2: In our review of 97 trials, only 3 PtDAs overtly addressed the needs of lower health literacy users. In 90% of trials, user health literacy and readability of the PtDA were not reported. However, increases in knowledge and informed choice were reported in those studies

  4. Adresse inconnue / Address unknown / Suchwiin Bulmyeong

    Serge Gruzinski

    2005-03-01

    Full Text Available Tous les films asiatiques parlent de métissage, même ceux qui se présentent comme de vastes fresques historiques perdues dans le temps. Les emprunts aux traditions hollywoodiennes et européennes n'ont cessé d'enrichir une cinématographie aussi ancienne que celle du monde occidental. Dans Adresse inconnue (Address unknown le cinéaste coréen Kim Ki-duk explore l'expérience du métissage et le corps du métis à la frontière entre Corée du Nord et Corée du sud. Fils d'un GI américain et noir et d...

  5. Adresse inconnue / Address unknown / Suchwiin Bulmyeong

    Serge Gruzinski

    2005-01-01

    Tous les films asiatiques parlent de métissage, même ceux qui se présentent comme de vastes fresques historiques perdues dans le temps. Les emprunts aux traditions hollywoodiennes et européennes n'ont cessé d'enrichir une cinématographie aussi ancienne que celle du monde occidental. Dans Adresse inconnue (Address unknown) le cinéaste coréen Kim Ki-duk explore l'expérience du métissage et le corps du métis à la frontière entre Corée du Nord et Corée du sud. Fils d'un GI américain et noir et d'...

  6. How is environmental conflict addressed by SIA?

    Barrow, C.J.

    2010-01-01

    The fields of Environmental Conflict Management (ECM), Environmental Conflict Resolution (ECR), and Peace and Conflict Impact Assessment (PCIA) have become well established; however, as yet there has not been much use of Social Impact Assessment (SIA) to manage environmental conflicts. ECM, ECR and PCIA are mainly undertaken when problems are advanced or, more likely, have run their course (post-conflict). This paper examines how conflict is addressed by SIA and whether there is potential to develop it for more proactive assessment of conflicts (pre-conflict or while things develop). SIA has the potential to identify and clarify the cause(s) of environmental and natural resources conflicts, and could possibly enable some avoidance or early mitigation. A promising approach may be for 'conflict-aware' SIA to watch for critical conflict stages or thresholds and to monitor stakeholders. Effective conflict-aware SIA might also significantly contribute to efforts to achieve sustainable development.

  7. Applying evolutionary biology to address global challenges

    Carroll, Scott P.; Jørgensen, Peter Søgaard; Kinnison, Michael T.; Bergstrom, Carl T.; Denison, R. Ford; Gluckman, Peter; Smith, Thomas B.; Strauss, Sharon Y.; Tabashnik, Bruce E.

    2014-01-01

    Two categories of evolutionary challenges result from escalating human impacts on the planet. The first arises from cancers, pathogens and pests that evolve too quickly, and the second from the inability of many valued species to adapt quickly enough. Applied evolutionary biology provides a suite of strategies to address these global challenges that threaten human health, food security, and biodiversity. This review highlights both progress and gaps in genetic, developmental and environmental manipulations across the life sciences that either target the rate and direction of evolution, or reduce the mismatch between organisms and human-altered environments. Increased development and application of these underused tools will be vital in meeting current and future targets for sustainable development. PMID:25213376

  8. Addressing Safeguards Challenges for the Future

    Majali, Raed; Yim, Man-Sung [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2015-10-15

    IAEA safeguard system is considered the corner stone of the international nuclear nonproliferation regime. Effective implementation of this legal instrument enables the IAEA to draw a conclusion with a high degree of confidence on the peaceful use of nuclear material and activities in the state. This paper aims to provide an opportunity to address various challenges encountered by IAEA. Strengthening safeguards system for verification is one of the most urgent challenges facing the IAEA. The IAEA should be able to provide credible assurance not only about declared use of nuclear material and facilities but also about the absence of undeclared material and activities. Implementation of IAEA safeguards continue to play a vital role within the nuclear non-proliferation regime. IAEA must move towards more enhanced safeguards system that is driven by the full use of all the safeguards available relevant information. Safeguards system must be responsive to evolving challenges and continue innovation through efficient implementations of more effective safeguards.

  9. Addressing Complexity in Environmental Management and Governance

    Sabrina Kirschke

    2017-06-01

    Full Text Available Governance for complex problem solving has been increasingly discussed in environmental sustainability research. Above all, researchers continuously observe that sustainability problems are complex or “wicked”, and suggest participatory models to address these problems in practice. In order to add to this debate, this study suggests a more differentiated theoretical approach to define governance for complex environmental problem solving than in previous studies. The approach consists of two vital steps: First, we operationalize complexity and define management strategies for solving environmental sustainability problems based on findings from psychology research. Second, we identify governance strategies that facilitate these management strategies. Linking those strategies suggests that the role of diverse institutions, actors, and interactions differs for five key dimensions of complexity: goals, variables, dynamics, interconnections, and informational uncertainty. The results strengthen systematic analyses of environmental sustainability problems in both theory and practice.

  10. Selected international efforts to address climate change

    Seki, M.; Christ, R. [Atmosphere Unit, United Nations Environment Programme UNEP, Nairobi (Kenya)

    1995-12-31

    Over the past two decades, concern about human-induced climate change has become an increasingly important item on the environmental and political agenda. The signing of the United Nations Framework Convention on Climate Change and the adoption of Agenda 21 at the United Nations Conference on Environment and Development in Rio de Janeiro in 1992 provided international organizations and the nations of the world with a new focus for climate-related activities. Although there remains considerable scientific uncertainty about the extent, magnitude, and rate of climate change and the impacts of such change, actions to address climate change have been initiated both internationally and nationally. Major international activities include the World Climate Programme, the Intergovernmental Panel on Climate Change, the United Nations Framework Convention on Climate Change. and the United Nations Environment Program me. 16 refs.

  11. Battling with breast cancer - addressing the issues

    Amin, S; Wahid, N; Wasim, B; Tabassum, S [Patel Hospital Gulshan-e-Iqbal, Karachi (Pakistan)

    2011-06-15

    In the background of the current situation of breast cancer in Pakistan, with its rising incidence and mortality, non afford ability and inaccessibility to screening, diagnosis and treatment, Patel Hospital took up the task of addressing these issues at a local level, by initiating an annual free breast camp in the year 2006. In 2008 an inclusion criteria was defined to focus on high risk women for breast cancer. A comparative analysis over a period of three years was done. In the focused camps, in which 28% patients were found to have a positive family history. Most women were symptomatic. Total 11 patients were diagnosed to have cancer after evaluation. Six patients underwent definitive treatment. A problem with lack of awareness, regarding screening and treatment protocols was identified. Family history seems to be an important risk factor in our set up signifying the need to introduce extensive screening programmes. (author)

  12. Battling with breast cancer - addressing the issues

    Amin, S.; Wahid, N.; Wasim, B.; Tabassum, S.

    2011-01-01

    In the background of the current situation of breast cancer in Pakistan, with its rising incidence and mortality, non afford ability and inaccessibility to screening, diagnosis and treatment, Patel Hospital took up the task of addressing these issues at a local level, by initiating an annual free breast camp in the year 2006. In 2008 an inclusion criteria was defined to focus on high risk women for breast cancer. A comparative analysis over a period of three years was done. In the focused camps, in which 28% patients were found to have a positive family history. Most women were symptomatic. Total 11 patients were diagnosed to have cancer after evaluation. Six patients underwent definitive treatment. A problem with lack of awareness, regarding screening and treatment protocols was identified. Family history seems to be an important risk factor in our set up signifying the need to introduce extensive screening programmes. (author)

  13. Hybrid content addressable memory MSD arithmetic

    Li, Yao; Kim, Dai Hyun; Kostrzewski, Andrew A.; Eichmann, George

    1990-07-01

    The modified signed-digit (MSD) number system, because of its inherent weak interdigit dependance, has been suggested as a useful means for a fast and parallel digital arithmetic. To maintain a fast processing speed, a single-stage holographic optical content-addressable memory (CAM) based MSD algorithm was suggested. In this paper, a novel non-holographic opto-electronic CAM based fast MSD addition processing architecture is proposed. The proposed concept has been verified with our first-order proof-of-principle experiments. A figure of merit comparison of this and other existing approaches is also presented. Based on this key opto-electronic CAM element, implementation of more sophisticated I'VISD arithmetic, such as optical MSD subtraction and multiplication operations, are proposed.

  14. Addressing consumerization of IT risks with nudging

    Iryna Yevseyeva

    2015-01-01

    Full Text Available In this work we address the main issues of Information Technology (IT consumerization that are related to security risks, and vulnerabilities of devices used within Bring Your Own Device (BYOD strategy in particular. We propose a ‘soft’ mitigation strategy for user actions based on nudging, widely applied to health and social behavior influence. In particular, we propose a complementary, less strict, more flexible Information Security policies, based on risk assessment of device vulnerabilities and threats to corporate data and devices, combined with a strategy of influencing security behavior by nudging. We argue that nudging, by taking into account the context of the decision-making environment, and the fact that the employee may be in better position to make a more appropriate decision, may be more suitable than strict policies in situations of uncertainty of security-related decisions. Several examples of nudging are considered for different tested and potential scenarios in security context.

  15. Voltammetry and single-molecule in situ scanning tunneling microscopy of laccases and bilirubin oxidase in electrocatalytic dioxygen reduction on Au(111) single-crystal electrodes

    Climent, Victor; Zhang, Jingdong; Friis, Esben Peter

    2012-01-01

    Laccases (E.C. 1.10.3.2) are multicopper oxidases catalytically active in the oxidation of diphenolics and related compounds by molecular dioxygen. The laccases contain a single-copper type I center and a trinuclear cluster of a single-copper type II and a dinuclear type III center. The oxidation...

  16. Alkylation of gold surface by treatment with C18H37HgOTs and anodic Hg stripping

    Mucha, Malgorzata; Kaletová, Eva; Kohutová, Anna; Scholz, F.; Stensrud, Elizabeth; Stibor, Ivan; Pospíšil, Lubomír; Wrochem von, F.; Michl, Josef

    2013-01-01

    Roč. 135, č. 15 (2013), s. 5669-5677 ISSN 0002-7863 R&D Projects: GA ČR GA203/07/1619; GA ČR GA203/09/0705 EU Projects: European Commission(XE) 213382 - FUNMOL; European Commission(XE) 227756 - DIPOLAR ROTOR ARRAY Institutional support: RVO:61388963 ; RVO:61388955 Keywords : self-assembled monolayers * altitudinal molecular rotors * AU(111) * mercury Subject RIV: CC - Organic Chemistry Impact factor: 11.444, year: 2013

  17. Addressing the Sustainability of Groundwater Extraction in California Using Hydrochronology

    Moran, J. E.; Visser, A.; Singleton, M. J.; Esser, B. K.

    2017-12-01

    In urban and agricultural settings in California, intense pressure on water supplies has led to extensive managed aquifer recharge and extensive overdraft in these areas, respectively. The California Sustainable Groundwater Management Act (SGMA) includes criteria for pumping that maintains groundwater levels and basin storage, and avoids stream depletion and degradation of water quality. Most sustainability plans will likely use water level monitoring and water budget balancing based on integrated flow models as evidence of compliance. However, hydrochronology data are applicable to several of the criteria, and provide an independent method of addressing questions related to basin turnover time, recharge rate, surface water-groundwater interaction, and the age distribution at pumping wells. We have applied hydrochronology (mainly tritium-helium groundwater age dating and extrinsic tracers) in urban areas to delineate flowpaths of artificially recharged water, to identify stagnant zones bypassed by the engineered flow system, and to predict vulnerability of drinking water sources to contamination. In agricultural areas, we have applied multi-tracer hydrochronology to delineate groundwater stratigraphy, to identify paleowater, and to project future nitrate concentrations in long-screened wells. This presentation will describe examples in which groundwater dating and other tracer methods can be applied to directly address the SGMA criteria for sustainable groundwater pumping.

  18. Addressing data heterogeneity: Lessons learned from a multimedia risk assessment

    Oezkaynak, H.; Xue, Jianping; Butler, D.A.; Haroun, L.A.; MacDonell, M.M.; Fingleton, D.J.

    1991-01-01

    Cleanup activities are currently being conducted by the US Department of Energy (DOE) at a former chemical plant site that has been inactive for more than 20 years. The Army produced nitroaromatic explosives at the 220-acre site during the 1940s, and radioactive materials of the uranium and thorium series were processed there by DOE's predecessor agency during the 1950s and 1960s. Chemical and radioactive contaminants are present in soil, surface water, sediment, and groundwater at the site as a result of both past releases and disposal activities and subsequent contaminant migration. Samples have been collected from these media over a number of years under both DOE's environmental monitoring program and the site characterization program of the Superfund process. Results of samples analyses have been compiled in a computerized data base. These data are being evaluated in the context of potential exposure pathways that are currently present at the site or that may be present in the future, in order to estimate possible adverse impacts to human health and the environment in the absence of cleanup. This paper discusses the methodology used to address associated tasks and the lessons learned during the assessment process. Statistical issues and recommended future directions for dealing with technical aspects of this project and with similar multimedia risk assessment projects are addressed in the final discussion. 10 refs., 9 figs., 1 tab

  19. Implementation of a Network Address Translation Mechanism Over IPv6

    Baumgartner, Trevor

    2004-01-01

    ...; however, NAT provides several other benefits. NAT can be used to mask the internal IP addresses of an Intranet - IPv6, the emerging standard for Internet addressing, provides three times the number of bits for IP addressing...

  20. Littoral Combat Ship: Need to Address Fundamental Weaknesses in LCS and Frigate Acquisition Strategies

    2016-06-01

    LITTORAL COMBAT SHIP Need to Address Fundamental Weaknesses in LCS and Frigate Acquisition Strategies Report to...Office Highlights of GAO-16-356, a report to congressional committees June 2016 LITTORAL COMBAT SHIP Need to Address Fundamental Weaknesses in...capabilities of the LCS—a small surface combatant (SSC) consisting of a ship and reconfigurable mission packages built by two shipyards as different

  1. 75 FR 41790 - Address Management Services-Elimination of the Manual Card Option for Address Sequencing Services

    2010-07-19

    .... The authority citation for 39 CFR Part 111 continues to read as follows: Authority: 5 U.S.C. 552(a... addresses (including rural address conversions to city-style addressing). For each 5-digit ZIP Code grouping... customer includes a rural-style address (RR/box number) in an address file submitted for sequencing, and a...

  2. Global Governance Mechanisms to Address Antimicrobial Resistance.

    Padiyara, Ponnu; Inoue, Hajime; Sprenger, Marc

    2018-01-01

    Since their discovery, antibiotics, and more broadly, antimicrobials, have been a cornerstone of modern medicine. But the overuse and misuse of these drugs have led to rising rates of antimicrobial resistance, which occurs when bacteria adapt in ways that render antibiotics ineffective. A world without effective antibiotics can have drastic impacts on population health, global development, and the global economy. As a global common good, antibiotic effectiveness is vulnerable to the tragedy of the commons, where a shared limited resource is overused by a community when each individual exploits the finite resource for their own benefit. A borderless threat like antimicrobial resistance requires global governance mechanisms to mitigate its emergence and spread, and it is the responsibility of all countries and relevant multilateral organizations. These mechanisms can be in the form of legally binding global governance mechanisms such as treaties and regulatory standards or nonbinding mechanisms such as political declarations, resolutions, or guidelines. In this article, we argue that while both are effective methods, the strong, swift, and coordinated action needed to address rising rates of antimicrobial resistance will be better served through legally binding governance mechanisms.

  3. Addressing terrain masking in orbital reconnaissance

    Mehta, Sharad; Cico, Luke

    2012-06-01

    During aerial orbital reconnaissance, a sensor system is mounted on an airborne platform for imaging a region on the ground. The latency between the image acquisition and delivery of information to the end-user is critical and must be minimized. Due to fine ground pixel resolution and a large field-of-view for wide-area surveillance applications, a massive volume of data is gathered and imagery products are formed using a real-time multi-processor system. The images are taken at oblique angles, stabilized and ortho-rectified. The line-of-sight of the sensor to the ground is often interrupted by terrain features such as mountains or tall structures as depicted in Figure1. The ortho-rectification process renders the areas hidden from the line-of sight of the sensor with spurious information. This paper discusses an approach for addressing terrain masking in size, weight, and power (SWaP) and memory-restricted onboard processing systems.

  4. Addressing Underrepresentation: Physics Teaching for All

    Rifkin, Moses

    2016-02-01

    Every physics teacher wants to give his or her students the opportunity to learn physics well. Despite these intentions, certain groups of students—including women and underrepresented minorities (URMs)—are not taking and not remaining in physics. In many cases, these disturbing trends are more significant in physics than in any other science. This is a missed opportunity for our discipline because demographic diversity strengthens science. The question is what we can do about these trends in our classrooms, as very few physics teachers have been explicitly prepared to address them. In this article, I will share some steps that I've taken in my classroom that have moved my class in the right direction. In the words of Nobel Prize-winning physicist Carl Wieman and psychologists Lauren Aguilar and Gregory Walton: "By investing a small amount of class time in carefully designed and implemented interventions, physics teachers can promote greater success among students from diverse backgrounds. Ultimately, we hope such efforts will indeed improve the diversity and health of the physics profession."

  5. Understanding and addressing the Schoolies phenomenon.

    Pettigrew, Simone; Biagioni, Nicole; Daube, Mike; Jones, Sandra C; Chikritzhs, Tanya; Kirby, Gary

    2015-04-01

    This study qualitatively explored Western Australian school leavers' alcohol-related experiences during the Schoolies period to generate insights for the purpose of intervention design. This is in the context of an impending change in the age of Western Australian students completing secondary school which, for the first time, will see around half being of legal age to purchase alcohol. Fifty-four 18-21-year-olds provided reflections via an emailed introspection on their experiences in the immediate post-school period. This provided access to the views of those who chose to attend events and consume large amounts of alcohol, those who attended events but refrained from excessive alcohol consumption, and those who elected to either avoid Schoolies events or engage in alternative celebrations. The data were coded and analysed using NVivo10. Three primary themes were identified that related to the perceived role of alcohol during Schoolies, the range of associated rite-of-passage rituals, and the strategies used by some Leavers to avoid alcohol and its consequences during the Schoolies period. Students and parents constitute important target groups for interventions designed to address alcohol-related harms during Schoolies. In the WA context, legislation on secondary supply and controlled purchase, as recommended by health and police authorities, could reduce harms that are likely to result from the change in the age of school leavers. Suggestions for alternative pastimes to promote to school leavers are provided. © 2015 Public Health Association of Australia.

  6. Quantitative tools for addressing hospital readmissions

    Lagoe Ronald J

    2012-11-01

    Full Text Available Abstract Background Increased interest in health care cost containment is focusing attention on reduction of hospital readmissions. Major payors have already developed financial penalties for providers that generate excess readmissions. This subject has benefitted from the development of resources such as the Potentially Preventable Readmissions software. This process has encouraged hospitals to renew efforts to improve these outcomes. The aim of this study was to describe quantitative tools such as definitions, risk estimation, and tracking of patients for reducing hospital readmissions. Findings This study employed the Potentially Preventable Readmissions software to develop quantitative tools for addressing hospital readmissions. These tools included two definitions of readmissions that support identification and management of patients. They also included analytical approaches for estimation of the risk of readmission for individual patients by age, discharge status of the initial admission, and severity of illness. They also included patient specific spreadsheets for tracking of target populations and for evaluation of the impact of interventions. Conclusions The study demonstrated that quantitative tools including the development of definitions of readmissions, estimation of the risk of readmission, and patient specific spreadsheets could contribute to the improvement of patient outcomes in hospitals.

  7. Assessing what to address in science communication.

    Bruine de Bruin, Wändi; Bostrom, Ann

    2013-08-20

    As members of a democratic society, individuals face complex decisions about whether to support climate change mitigation, vaccinations, genetically modified food, nanotechnology, geoengineering, and so on. To inform people's decisions and public debate, scientific experts at government agencies, nongovernmental organizations, and other organizations aim to provide understandable and scientifically accurate communication materials. Such communications aim to improve people's understanding of the decision-relevant issues, and if needed, promote behavior change. Unfortunately, existing communications sometimes fail when scientific experts lack information about what people need to know to make more informed decisions or what wording people use to describe relevant concepts. We provide an introduction for scientific experts about how to use mental models research with intended audience members to inform their communication efforts. Specifically, we describe how to conduct interviews to characterize people's decision-relevant beliefs or mental models of the topic under consideration, identify gaps and misconceptions in their knowledge, and reveal their preferred wording. We also describe methods for designing follow-up surveys with larger samples to examine the prevalence of beliefs as well as the relationships of beliefs with behaviors. Finally, we discuss how findings from these interviews and surveys can be used to design communications that effectively address gaps and misconceptions in people's mental models in wording that they understand. We present applications to different scientific domains, showing that this approach leads to communications that improve recipients' understanding and ability to make informed decisions.

  8. Addressing Issues for Land Change Science

    Braimoh, Ademola; Huang, He Qing

    2009-09-01

    Workshop on Vulnerability and Resilience of Land Systems in Asia; Beijing, China, 15-17 June 2009; There is a growing international community of scholars who work within the interdisciplinary field of land change science, a scientific domain that seeks to understand the dynamics of the land system as a coupled human-environment system. A coupled human-environment system is one in which the social and biophysical subsystems are intertwined so that the system's condition and responses to external forcing are based on the synergy of the two subsystems. Research on land system vulnerability, defined as a function of exposure and sensitivity to natural and anthropogenic perturbations, such as climate variability and sudden changes in macroeconomic conditions and the ability to cope with the impacts of those perturbations, is a fundamental component of land change science. To address issues related to land system vulnerability, the Global Land Project (GLP; http://www.glp-beijing.org.cn/index.php and http://www.glp.hokudai.ac.jp) brought together an interdisciplinary group of researchers with backgrounds ranging from environmental to social sciences. Participants came from both developed and developing countries. The workshop sought to (1) improve knowledge of the causal processes that affect a system's vulnerability and capacity to cope with different perturbations and (2) identify factors that hinder the integration of vulnerability assessment into policies and decision making.

  9. Convolving optically addressed VLSI liquid crystal SLM

    Jared, David A.; Stirk, Charles W.

    1994-03-01

    We designed, fabricated, and tested an optically addressed spatial light modulator (SLM) that performs a 3 X 3 kernel image convolution using ferroelectric liquid crystal on VLSI technology. The chip contains a 16 X 16 array of current-mirror-based convolvers with a fixed kernel for finding edges. The pixels are located on 75 micron centers, and the modulators are 20 microns on a side. The array successfully enhanced edges in illumination patterns. We developed a high-level simulation tool (CON) for analyzing the performance of convolving SLM designs. CON has a graphical interface and simulates SLM functions using SPICE-like device models. The user specifies the pixel function along with the device parameters and nonuniformities. We discovered through analysis, simulation and experiment that the operation of current-mirror-based convolver pixels is degraded at low light levels by the variation of transistor threshold voltages inherent to CMOS chips. To function acceptable, the test SLM required the input image to have an minimum irradiance of 10 (mu) W/cm2. The minimum required irradiance can be further reduced by adding a photodarlington near the photodetector or by increasing the size of the transistors used to calculate the convolution.

  10. Structure formation and surface chemistry of ionic liquids on model electrode surfaces—Model studies for the electrode | electrolyte interface in Li-ion batteries

    Buchner, Florian; Uhl, Benedikt; Forster-Tonigold, Katrin; Bansmann, Joachim; Groß, Axel; Behm, R. Jürgen

    2018-05-01

    Ionic liquids (ILs) are considered as attractive electrolyte solvents in modern battery concepts such as Li-ion batteries. Here we present a comprehensive review of the results of previous model studies on the interaction of the battery relevant IL 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([BMP]+[TFSI]-) with a series of structurally and chemically well-defined model electrode surfaces, which are increasingly complex and relevant for battery applications [Ag(111), Au(111), Cu(111), pristine and lithiated highly oriented pyrolytic graphite (HOPG), and rutile TiO2(110)]. Combining surface science techniques such as high resolution scanning tunneling microscopy and X-ray photoelectron spectroscopy for characterizing surface structure and chemical composition in deposited (sub-)monolayer adlayers with dispersion corrected density functional theory based calculations, this work aims at a molecular scale understanding of the fundamental processes at the electrode | electrolyte interface, which are crucial for the development of the so-called solid electrolyte interphase (SEI) layer in batteries. Performed under idealized conditions, in an ultrahigh vacuum environment, these model studies provide detailed insights on the structure formation in the adlayer, the substrate-adsorbate and adsorbate-adsorbate interactions responsible for this, and the tendency for chemically induced decomposition of the IL. To mimic the situation in an electrolyte, we also investigated the interaction of adsorbed IL (sub-)monolayers with coadsorbed lithium. Even at 80 K, postdeposited Li is found to react with the IL, leading to decomposition products such as LiF, Li3N, Li2S, LixSOy, and Li2O. In the absence of a [BMP]+[TFSI]- adlayer, it tends to adsorb, dissolve, or intercalate into the substrate (metals, HOPG) or to react with the substrate (TiO2) above a critical temperature, forming LiOx and Ti3+ species in the latter case. Finally, the formation of stable

  11. Address Points - COUNTY_ADDRESS_POINTS_IDHS_IN: Address Points Maintained by County Agencies in Indiana (Indiana Department of Homeland Security, Point feature class)

    NSGIC State | GIS Inventory — COUNTY_ADDRESS_POINTS_IDHS_IN is an ESRI Geodatabase point feature class that contains address points maintained by county agencies in Indiana, provided by personnel...

  12. ALI (Autonomous Lunar Investigator): Revolutionary Approach to Exploring the Moon with Addressable Reconfigurable Technology

    Clark, P. E.; Curtis, S. A.; Rilee, M. L.; Floyd, S. R.

    2005-01-01

    Addressable Reconfigurable Technology (ART) based structures: Mission Concepts based on Addressable Reconfigurable Technology (ART), originally studied for future ANTS (Autonomous Nanotechnology Swarm) Space Architectures, are now being developed as rovers for nearer term use in lunar and planetary surface exploration. The architecture is based on the reconfigurable tetrahedron as a building block. Tetrahedra are combined to form space-filling networks, shaped for the required function. Basic structural components are highly modular, addressable arrays of robust nodes (tetrahedral apices) from which highly reconfigurable struts (tetrahedral edges), acting as supports or tethers, are efficiently reversibly deployed/stowed, transforming and reshaping the structures as required.

  13. Final Report on Internet Addressable Lightswitch; TOPICAL

    Rubinstein, Francis; Pettler, Peter

    2001-01-01

    This report describes the work performed to develop and test a new switching system and communications network that is useful for economically switching lighting circuits in existing commercial buildings. The first section of the report provides the general background of the IBECS (Integrated Building Environmental Communications System) research and development work as well as the context for the development of the new switching system. The research and development effort that went into producing the first proof-of-concept (the IBECS Addressable Power Switch or APS) and the physical prototype of that concept is detailed in the second section. In the third section of the report, we detail the refined Powerline Carrier Based IBECS Title 24 Wall Switch system that evolved from the APS prototype. The refined system provided a path for installing IBECS switching technology in existing buildings that may not be already wired for light level switching control. The final section of the report describes the performance of the IBECS Title 24 Switch system as applied to a small demonstration in two offices at LBNL's Building 90. We learned that the new Powerline Carrier control systems (A-10 technology) that have evolved from the early X-10 systems have solved most of the noise problems that dogged the successful application of X-10 technologies in commercial buildings. We found that the new A-10 powerline carrier control technology can be reliable and effective for switching lighting circuits even in electrically noisy office environments like LBNL. Thus we successfully completed the task objectives by designing, building and demonstrating a new switching system that can provide multiple levels of light which can be triggered either from specially designed wall switches or from a digital communications network. By applying commercially available powerline carrier based technologies that communicate over the in-place lighting wiring system, this type of control can be

  14. DDT and Malaria Prevention: Addressing the Paradox

    Bouwman, Hindrik; van den Berg, Henk; Kylin, Henrik

    2011-01-01

    Background The debate regarding dichlorodiphenyltrichloroethane (DDT) in malaria prevention and human health is polarized and can be classified into three positions: anti-DDT, centrist-DDT, pro-DDT. Objective We attempted to arrive at a synthesis by matching a series of questions on the use of DDT for indoor residual spraying (IRS) with literature and insights, and to identify options and opportunities. Discussion Overall, community health is significantly improved through all available malaria control measures, which include IRS with DDT. Is DDT “good”? Yes, because it has saved many lives. Is DDT safe as used in IRS? Recent publications have increasingly raised concerns about the health implications of DDT. Therefore, an unqualified statement that DDT used in IRS is safe is untenable. Are inhabitants and applicators exposed? Yes, and to high levels. Should DDT be used? The fact that DDT is “good” because it saves lives, and “not safe” because it has health and environmental consequences, raises ethical issues. The evidence of adverse human health effects due to DDT is mounting. However, under certain circumstances, malaria control using DDT cannot yet be halted. Therefore, the continued use of DDT poses a paradox recognized by a centrist-DDT position. At the very least, it is now time to invoke precaution. Precautionary actions could include use and exposure reduction. Conclusions There are situations where DDT will provide the best achievable health benefit, but maintaining that DDT is safe ignores the cumulative indications of many studies. In such situations, addressing the paradox from a centrist-DDT position and invoking precaution will help design choices for healthier lives. PMID:21245017

  15. Nuclear techniques to address HAB concerns

    Vu Nhu Ngoc; Phan Son; Nguyen Ngoc Lam and Chu Van Thuoc

    2004-01-01

    In December, 1998, The Project Formulation meeting on application of Nuclear Techniques to address red tide (Harmful Algal Bloom concerns) was held in Manila Philippines. This is an IAEA/RCA project with the participation of Australia, China, Indonesia, Malaysia, Pakistan, The Philippines, Thailand and Vietnam. The main objectives of this project (RAS/8/076) included: - Conduct of segmentation studies to gain information on the natural histories of sediments and to correlated these with Red Tide occurrences. - Development of descriptive and predictive of the behaviour of Algal Bloom as affected by the interplay of the causative organism with the environment parameters in the water column and sediments. - Development and field testing of a rapid assay technique based on tritium - labeled saxitoxin for toxin determination. The first phase has been completed in 2002 and the second phase will be completed in 2004. In the two years of 2001 - 2002 Ted Tide occurred in very larger area in Vietnam, for example, in the coast of Binh Thuan Province with the density of 39.10 9 cells/litre. The Ministry of science - technology environment of Vietnam has support 5.000 USD each years for sediment and algal sampling in Cam Ranh Bay (Nha Trang, 11 o 45N and 10 o 15E) and Ha Long Bay in the North - East of Vietnam (21 o 15 and 107 o 3E) and in 2003 in Tuy Phong Bay (Binh Thuan province) (10 o 15N, 108 o 45E). Three sediment core has been taken from Cam Ranh Bay, Ha Long Bay and Tuy Phong Bay. The volume of sediment core is Φ = 8 cm and h = 60 cm. The algal samples have been collected by Bongo nets in Cam Ranh, Ha Long Bay and Tuy Phong Bay. (author)

  16. Building partnerships to address the HIV epidemic.

    Chua, A C; Leo, Y S; Lee, C C

    2008-05-01

    Batam is one of the islands comprising the Riau Province in Indonesia, and is closest to Singapore. It is a popular destination of many Singaporeans. Surveillance reports among commercial sex workers conducted in Batam showed the prevalence rate of human immunodeficiency virus (HIV) is 16.2 percent. At the end of 2006, the total number of HIV-infected Singaporeans was 3,060, the majority being infected via heterosexual transmission. The aim of the Indonesian government is to rapidly scale up HIV treatment to those needing it. One of the factors critical to the rapid scale-up is healthcare worker training. An intersectoral collaboration addressing the issue of HIV care and treatment with a hospital in Batam was created. The first activity of the collaboration was a two-day HIV training course conducted in February 2007. The aim of the course was to provide a basic understanding of HIV, as well as knowledge on common opportunistic infections that may present to a general hospital or clinical setting. 34 doctors from 23 institutions in Batam and three doctors from two hospitals in the Riau Islands attended the two-day HIV training course. The participants found the training very useful and highly relevant. This first HIV training provided a foundation to build on further HIV education. It is our belief that through the HIV training programme, there will be more awareness of HIV among the various medical institutions in Batam. As the HIV epidemic knows no borders, working with neighbouring countries is one strategy that deserves attention.

  17. State of the Union Address, 1997. Remarks by the President in State of the Union Address.

    Executive Office of the President, Washington, DC.

    This document contains the text of President Clinton's State of the Union Address, delivered on February 4, 1997. The President issues a call to action to work together to prepare America for the twenty-first century. The United States must attend to the unfinished business of balancing the budget, enacting bipartisan campaign-finance reform, and…

  18. Emerging trends in surface metrology

    Lonardo, P.M.; Lucca, D.A.; De Chiffre, Leonardo

    2002-01-01

    Recent advancements and some emerging trends in the methods and instruments used for surface and near surface characterisation are presented, considering the measurement of both topography and physical properties. In particular, surfaces that present difficulties in measurement or require new...... procedures are considered, with emphasis on measurements approaching the nanometre scale. Examples of new instruments and promising innovations for roughness measurement and surface integrity characterisation are presented. The new needs for tolerancing, traceability and calibration are also addressed....

  19. Addressing contrasting cognitive models in scientific collaboration

    Diviacco, P.

    2012-04-01

    If the social aspects of scientific communities and their internal dynamics is starting to be recognized and acknowledged in the everyday lives of scientists, it is rather difficult for them to find tools that could support their activities consistently with this perspective. Issues span from gathering researchers to mutual awareness, from information sharing to building meaning, with the last one being particularly critical in research fields as the geo-sciences, that deal with the reconstruction of unique, often non-reproducible, and contingent processes. Reasoning here is, in fact, mainly abductive, allowing multiple and concurrent explanations for the same phenomenon to coexist. Scientists bias one hypothesis over another not only on strictly logical but also on sociological motivations. Following a vision, scientists tend to evolve and isolate themselves from other scientists creating communities characterized by different cognitive models, so that after some time these become incompatible and scientists stop understanding each other. We address these problems as a communication issue so that the classic distinction into three levels (syntactic, semantic and pragmatic) can be used. At the syntactic level, we highlight non-technical obstacles that condition interoperability and data availability and transparency. At the semantic level, possible incompatibilities of cognitive models are particularly evident, so that using ontologies, cross-domain reconciliation should be applied. This is a very difficult task to perform since the projection of knowledge by scientists, in the designated community, is political and thus can create a lot of tension. The strategy we propose to overcome these issues pertains to pragmatics, in the sense that it is intended to acknowledge the cultural and personal factors each partner brings into the collaboration and is based on the idea that meaning should remain a flexible and contingent representation of possibly divergent views

  20. Evaluating Judicial Performance and Addressing Gender Bias

    Angela Melville

    2014-12-01

    Full Text Available Elek and Rottman argue that judicial evaluation is often biased against women and minority judges. The need to address bias is important, however often the desire for diversity seems so self-evident as to belie deeper analysis. This paper examines the two main rationales for gender equality on the bench. First, female judges are often considered necessary in order to bring a gendered perspective to judging, however it is argued that this rationale is flawed. Second, an alternative rationale based on equality and legitimacy is offered which avoids gender essentialism. While debates typically focus on these two rationales, a third rationale embraces both difference and equality/legitimacy. The presence of female judges has an important symbolic value which destabilises existing fraternal legal norms. Finally, increasing the number of female judges may not necessarily change judging, and this paper also analyses how the transformative potential offered by judicial diversity can work in practice. Elek y Rottman defienden que la evaluación judicial suele estar sesgada en contra de las mujeres y los jueces pertenecientes a minorías. La necesidad de abordar el sesgo es importante, sin embargo a menudo el deseo de diversidad parece tan evidente como para contradecir un análisis más profundo. Este artículo examina los dos motivos principales para la igualdad de género en el banquillo. En primer lugar, las mujeres jueces a menudo se consideran necesarias para aportar una perspectiva de género al hecho de juzgar, sin embargo, se defiende que este razonamiento es erróneo. En segundo lugar, se ofrece una alternativa lógica basada en la igualdad y la legitimidad que evita el esencialismo de género. Mientras que los debates suelen centrarse en estas dos razones, una tercera justificación abarca tanto la diferencia como la igualdad/legitimidad. La presencia de mujeres en la judicatura tiene un importante valor simbólico que desestabiliza las normas

  1. The 2016 Ferno Award Address: Three Things.

    Baker, Timothy B

    2017-08-01

    Researchers may optimize smoking treatment by addressing three research topics that have been relatively neglected. First, researchers have neglected to intensively explore how counseling contents affect smoking cessation success. Worldwide, millions of smokers are exposed to different smoking cessation contents and messages, yet existing research evidence does not permit strong inference about the value of particular counseling contents or strategies. Research in this area could enhance smoking outcomes and yield new insights into smoking motivation. Second, researchers have focused great attention on inducing smokers to make quit attempts when they contact healthcare systems; the success of such efforts may have plateaued. Also, the vast majority of quit attempts are self-quit attempts, largely unsuccessful, that occur outside such contacts. Researchers should explore strategies for using healthcare systems as conduits for digital- and other population-based interventions independent of healthcare visits. Such resources should be used to graft timely access to evidence-based intervention onto self-quitting, yielding evidence-based, patient-managed quit attempts. Third, most smoking treatments are assembled via selection of components based on informal synthesis of empirical and impressionistic evidence and are evaluated as a package. However, recent factorial experiments show that components of smoking treatments often interact meaningfully; for example, some components may interfere with the effectiveness of other components. Many extant treatments likely comprise suboptimal sets of components; future treatment development should routinely use factorial experiments to permit the assembly of components that yield additive or synergistic effects.Research in the above three areas should significantly advance our understanding of tobacco use and its treatment. A lack of relevant research, and the likely prospect of significant clinical and public health benefit

  2. Multi Sensor Approach to Address Sustainable Development

    Habib, Shahid

    2007-01-01

    The main objectives of Earth Science research are many folds: to understand how does this planet operates, can we model her operation and eventually develop the capability to predict such changes. However, the underlying goals of this work are to eventually serve the humanity in providing societal benefits. This requires continuous, and detailed observations from many sources in situ, airborne and space. By and large, the space observations are the way to comprehend the global phenomena across continental boundaries and provide credible boundary conditions for the mesoscale studies. This requires a multiple sensors, look angles and measurements over the same spot in accurately solving many problems that may be related to air quality, multi hazard disasters, public health, hydrology and more. Therefore, there are many ways to address these issues and develop joint implementation, data sharing and operating strategies for the benefit of the world community. This is because for large geographical areas or regions and a diverse population, some sound observations, scientific facts and analytical models must support the decision making. This is crucial for the sustainability of vital resources of the world and at the same time to protect the inhabitants, endangered species and the ecology. Needless to say, there is no single sensor, which can answer all such questions effectively. Due to multi sensor approach, it puts a tremendous burden on any single implementing entity in terms of information, knowledge, budget, technology readiness and computational power. And, more importantly, the health of planet Earth and its ability to sustain life is not governed by a single country, but in reality, is everyone's business on this planet. Therefore, with this notion, it is becoming an impractical problem by any single organization/country to bear this colossal responsibility. So far, each developed country within their means has proceeded along satisfactorily in implementing

  3. 21 CFR 1321.01 - DEA mailing addresses.

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false DEA mailing addresses. 1321.01 Section 1321.01 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE DEA MAILING ADDRESSES § 1321.01 DEA mailing addresses. The following table provides information regarding mailing addresses to be used...

  4. Addressing barriers to low carbon energy

    Berry, Fiona; Dunstan, Chris

    2012-01-01

    Full text: Two energy solutions gaining attention are cogeneration and trigeneration, mostly fuelled by natural gas, although other renewable sources can be used, such as sewage, agricultural waste and municipal waste. Trigeneration has become increasingly popular in Australia's urban centres as a relatively cost-effective means to cut the carbon-intensity of energy supply by more than half compared to traditional coal- fired electricity. Some examples of trigeneration projects include the City of Sydney's planned 360 megawatt trigeneration networks by 2030, the University of Technology Sydney's campus master plan and the six star Green Star Commonwealth Bank Place building in Sydney. Trigeneration and cogeneration can present opportunities such as addressing the issue of rising peak demand, which is a major driver for the current $9 billion per annum of network infrastructure spending. They can also face barriers. For example, depending on the current state of the network, additional network costs can be required to accommodate trigeneration. Furthermore, under the current National Electricity Market regulations and conventions, challenges do exist to timely and financially viable connection to the grid. Here we present two examples of barriers to trigeneration and cogeneration and solutions being considered and implemented. The University of Technology Sydney campus master plan is underway, with approximately 100,000sq.m of floor area being built by 2019 and includes plans for trigeneration. During the master planning phase of development, the university considered small trigeneration units in individual buildings in order to reduce the carbon intensity of electricity supply and deliver high ratings under Green Star ratings. When considering connecting trigeneration with the grid at multiple buildings on an individual basis, a number of barriers were encountered by UTS. The largest barrier was appropriate charging for connecting to and using the grid. However

  5. Interfacial and Surface Science | Materials Science | NREL

    Science group within the Material Science Center. He oversees research studies of surfaces and interfaces Interfacial and Surface Science Interfacial and Surface Science Image of irregular-outlined, light address a broad range of fundamental and applied issues in surface and interfacial science that are

  6. Chain-Branching Control of the Atomic Structure of Alkanethiol-Based Gold–Sulfur Interfaces

    Wang, Yun; Chi, Qijin; Zhang, Jingdong

    2011-01-01

    Density functional theory structure calculations at 0 K and simulations at 300 K of observed high-resolution in situ scanning tunneling microscopy (STM) images reveal three different atomic-interface structures for the self-assembled monolayers (SAMs) of three isomeric butanethiols on Au(111......): direct binding to the Au(111) surface without pitting, binding to adatoms above a regular surface with extensive pitting, and binding to adatoms with local surface vacancies and some pitting. Thermal motions are shown to produce some observed STM features, with a very tight energy balance controlling...

  7. Is prophetic discourse adequate to address global economic justice?

    Test

    2011-02-15

    Feb 15, 2011 ... of moral discourse adequately addresses issues of economic injustice. ... plays an indispensable role in addressing issues of global economic justice, but ...... governance in their business practices, to provide a tool for a.

  8. Using ICTs to Address Water Challenges in Uganda | IDRC ...

    Using ICTs to Address Water Challenges in Uganda ... the adaptive capacity of communities to address the issue of climate-induced water stress. ... It will do so by testing the electronic dissemination of seasonal forecasts, early warning ...

  9. Using ICTs to Address Water Challenges in Uganda | CRDI - Centre ...

    15 janv. 2012 ... Using ICTs to Address Water Challenges in Uganda ... adaptive capacity of communities to address the issue of climate-induced water stress. ... It will do so by testing the electronic dissemination of seasonal forecasts, early ...

  10. Vaal Triangle air pollution health study. Addressing South African problems

    Terblanche, P; Nel, R [CSIR Environmental Services, Pretoria (South Africa); Surridge, T [Dept. of Mineral and Energy Affairs (South Africa); Annegarn, H [Annegarn Environmental Research, Johannesburg (South Africa); Tosen, G [Eskom, Johannesburg (South Africa); Pols, A [CSIR Informationtek, Pretoria (South Africa)

    1996-12-31

    Situated in the central region of South Africa, the Vaal Triangle is an area which plays a vital role in driving the economic dynamo of South Africa. Also, because of the concentration of heavy industry, it is an area which provides a challenge in effective air pollution control. The Vaal Triangle lies within the Vaal River Basin, at an altitude of 1 500 m above sea level. Meteorological conditions in the area are highly conducive to the formation of surface temperature inversions, resulting in a poor dispersion potential. Because of multiple sources of air pollution in the area, poor dispersion conditions increase the risk pollution build-up and subsequent adverse impacts. The situation is further exacerbated by the continued combustion of coal in households, even after the electrification of residences. This is particularly chronic in the developing communities and during winter. Vaal Triangle Air Pollution Health Study (VAPS) was initiated in 1990 by the Department of Health, the Medical Research Council and major industries in the area to determine effects of air pollution on the health of the community. The final results of that study summarised in this article, and options to ameliorate problems are addressed. (author)

  11. Vaal Triangle air pollution health study. Addressing South African problems

    Terblanche, P.; Nel, R. [CSIR Environmental Services, Pretoria (South Africa); Surridge, T. [Dept. of Mineral and Energy Affairs (South Africa); Annegarn, H. [Annegarn Environmental Research, Johannesburg (South Africa); Tosen, G. [Eskom, Johannesburg (South Africa); Pols, A. [CSIR Informationtek, Pretoria (South Africa)

    1995-12-31

    Situated in the central region of South Africa, the Vaal Triangle is an area which plays a vital role in driving the economic dynamo of South Africa. Also, because of the concentration of heavy industry, it is an area which provides a challenge in effective air pollution control. The Vaal Triangle lies within the Vaal River Basin, at an altitude of 1 500 m above sea level. Meteorological conditions in the area are highly conducive to the formation of surface temperature inversions, resulting in a poor dispersion potential. Because of multiple sources of air pollution in the area, poor dispersion conditions increase the risk pollution build-up and subsequent adverse impacts. The situation is further exacerbated by the continued combustion of coal in households, even after the electrification of residences. This is particularly chronic in the developing communities and during winter. Vaal Triangle Air Pollution Health Study (VAPS) was initiated in 1990 by the Department of Health, the Medical Research Council and major industries in the area to determine effects of air pollution on the health of the community. The final results of that study summarised in this article, and options to ameliorate problems are addressed. (author)

  12. Vocatives and Other Direct Address Forms: A Contrastive Study

    Lilli Parrott

    2010-01-01

    In this paper I analyze Russian direct address forms, both the distinct truncated vocative and nominative-case direct address forms. I contrast the formal and functional restrictions on the truncated vocative with vocatives in other languages (e.g. Czech and Polish), and I compare the interpolation of Russian direct address forms in an utterance to the situation in English. While similarities are found both in the form and the usage of Russian direct address forms with those in other language...

  13. Analyzing the Messages of the State of the Union Address

    Kissling, Mark T.; Martell, Christopher C.

    2014-01-01

    In the era of smartphones and 24-hour news networks, the State of the Union address is a major event. All national media outlets--in print, on television, on the Internet--report on the address, some almost exclusively in the days leading up to and after the speech. In this article, considering their experiences teaching about the address, and…

  14. Research of future network with multi-layer IP address

    Li, Guoling; Long, Zhaohua; Wei, Ziqiang

    2018-04-01

    The shortage of IP addresses and the scalability of routing systems [1] are challenges for the Internet. The idea of dividing existing IP addresses between identities and locations is one of the important research directions. This paper proposed a new decimal network architecture based on IPv9 [11], and decimal network IP address from E.164 principle of traditional telecommunication network, the IP address level, which helps to achieve separation and identification and location of IP address, IP address form a multilayer network structure, routing scalability problem in remission at the same time, to solve the problem of IPv4 address depletion. On the basis of IPv9, a new decimal network architecture is proposed, and the IP address of the decimal network draws on the E.164 principle of the traditional telecommunication network, and the IP addresses are hierarchically divided, which helps to realize the identification and location separation of IP addresses, the formation of multi-layer IP address network structure, while easing the scalability of the routing system to find a way out of IPv4 address exhausted. In addition to modifying DNS [10] simply and adding the function of digital domain, a DDNS [12] is formed. At the same time, a gateway device is added, that is, IPV9 gateway. The original backbone network and user network are unchanged.

  15. Addressing Spatial Variability of Surface-Layer Wind with Long-Range WindScanners

    Berg, Jacob; Vasiljevic, Nikola; Kelly, Mark C.

    2015-01-01

    of the WindScanner data is high, although the fidelity of the estimated vertical velocity component is significantly limited by the elevation angles of the scanner heads. The system of long-range WindScanners presented in this paper is close to being fully operational, with the pilot study herein serving...

  16. PREFACE: Nanostructured surfaces

    Palmer, Richard E.

    2003-10-01

    We can define nanostructured surfaces as well-defined surfaces which contain lateral features of size 1-100 nm. This length range lies well below the micron regime but equally above the Ångstrom regime, which corresponds to the interatomic distances on single-crystal surfaces. This special issue of Journal of Physics: Condensed Matter presents a collection of twelve papers which together address the fabrication, characterization, properties and applications of such nanostructured surfaces. Taken together they represent, in effect, a status report on the rapid progress taking place in this burgeoning area. The first four papers in this special issue have been contributed by members of the European Research Training Network ‘NanoCluster’, which is concerned with the deposition, growth and characterization of nanometre-scale clusters on solid surfaces—prototypical examples of nanoscale surface features. The paper by Vandamme is concerned with the fundamentals of the cluster-surface interaction; the papers by Gonzalo and Moisala address, respectively, the optical and catalytic properties of deposited clusters; and the paper by van Tendeloo reports the application of transmission electron microscopy (TEM) to elucidate the surface structure of spherical particles in a catalyst support. The fifth paper, by Mendes, is also the fruit of a European Research Training Network (‘Micro-Nano’) and is jointly contributed by three research groups; it reviews the creation of nanostructured surface architectures from chemically-synthesized nanoparticles. The next five papers in this special issue are all concerned with the characterization of nanostructured surfaces with scanning tunnelling microscopy (STM) and atomic force microscopy (AFM). The papers by Bolotov, Hamilton and Dunstan demonstrate that the STM can be employed for local electrical measurements as well as imaging, as illustrated by the examples of deposited clusters, model semiconductor structures and real

  17. Highly sensitive covalently functionalized light-addressable potentiometric sensor for determination of biomarker

    Liang, Jintao [School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Guangxi Experiment Center of Information Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Guan, Mingyuan; Huang, Guoyin; Qiu, Hengming; Chen, Zhengcheng [School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Li, Guiyin, E-mail: liguiyin01@163.com [School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Guangxi Experiment Center of Information Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Huang, Yong, E-mail: huangyong503@126.com [School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Guangxi Experiment Center of Information Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China)

    2016-06-01

    A biomarker is related to the biological status of a living organism and shows great promise for the early prediction of a related disease. Herein we presented a novel structured light-addressable potentiometric sensor (LAPS) for the determination of a model biomarker, human immunoglobulin G (hIgG). In this system, the goat anti-human immunoglobulin G antibody was used as recognition element and covalently immobilized on the surface of light-addressable potentiometric sensor chip to capture human immunoglobulin G. Due to the light addressable capability of light-addressable potentiometric sensor, human immunoglobulin G dissolved in the supporting electrolyte solution can be detected by monitoring the potential shifts of the sensor. In order to produce a stable photocurrent, the laser diode controlled by field-programmable gate array was used as the light emitter to drive the light-addressable potentiometric sensor. A linear correlation between the potential shift response and the concentration of human immunoglobulin G was achieved and the corresponding regression equation was ΔV (V) = 0.00714C{sub hIgG} (μg/mL)–0.0147 with a correlation coefficient of 0.9968 over a range 0–150 μg/mL. Moreover, the light-addressable potentiometric sensor system also showed acceptable stability and reproducibility. All the results demonstrated that the system was more applicable to detection of disease biomarkers with simple operation, multiple-sample format and might hold great promise in various environmental, food, and clinical applications. - Highlights: • A novel structured light-addressable potentiometric sensor (LAPS) based on covalently functionalized membrane was designed. • The composition of the surface of LAPS chip was investigated by X-ray photoelectron spectroscopy (XPS). • hIgG dissolved in the supporting electrolyte solution can be detected by monitoring the potential shifts of LAPS.

  18. Minimal surfaces

    Dierkes, Ulrich; Sauvigny, Friedrich; Jakob, Ruben; Kuster, Albrecht

    2010-01-01

    Minimal Surfaces is the first volume of a three volume treatise on minimal surfaces (Grundlehren Nr. 339-341). Each volume can be read and studied independently of the others. The central theme is boundary value problems for minimal surfaces. The treatise is a substantially revised and extended version of the monograph Minimal Surfaces I, II (Grundlehren Nr. 295 & 296). The first volume begins with an exposition of basic ideas of the theory of surfaces in three-dimensional Euclidean space, followed by an introduction of minimal surfaces as stationary points of area, or equivalently

  19. Name-Based Address Mapping for Virtual Private Networks

    Surányi, Péter; Shinjo, Yasushi; Kato, Kazuhiko

    IPv4 private addresses are commonly used in local area networks (LANs). With the increasing popularity of virtual private networks (VPNs), it has become common that a user connects to multiple LANs at the same time. However, private address ranges for LANs frequently overlap. In such cases, existing systems do not allow the user to access the resources on all LANs at the same time. In this paper, we propose name-based address mapping for VPNs, a novel method that allows connecting to hosts through multiple VPNs at the same time, even when the address ranges of the VPNs overlap. In name-based address mapping, rather than using the IP addresses used on the LANs (the real addresses), we assign a unique virtual address to each remote host based on its domain name. The local host uses the virtual addresses to communicate with remote hosts. We have implemented name-based address mapping for layer 3 OpenVPN connections on Linux and measured its performance. The communication overhead of our system is less than 1.5% for throughput and less than 0.2ms for each name resolution.

  20. Rumble surfaces

    National Institute for Transport and Road

    1977-01-01

    Full Text Available Rumble surfaces are intermittent short lengths of coarse-textured road surfacings on which vehicle tyres produce a rumbling sound. used in conjunction with appropriate roadsigns and markings, they can reduce accidents on rural roads by alerting...

  1. Surface thermodynamics

    Garcia-Moliner, F.

    1975-01-01

    Basic thermodynamics of a system consisting of two bulk phases with an interface. Solid surfaces: general. Discussion of experimental data on surface tension and related concepts. Adsorption thermodynamics in the Gibbsian scheme. Adsorption on inert solid adsorbents. Systems with electrical charges: chemistry and thermodynamics of imperfect crystals. Thermodynamics of charged surfaces. Simple models of charge transfer chemisorption. Adsorption heat and related concepts. Surface phase transitions

  2. Discovery of IPV6 Router Interface Addresses via Heuristic Methods

    2015-09-01

    NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS DISCOVERY OF IPV6 ROUTER INTERFACE ADDRESSES VIA HEURISTIC METHODS by Matthew D. Gray September...AND SUBTITLE DISCOVERY OF IPV6 ROUTER INTERFACE ADDRESSES VIA HEURISTIC METHODS 5. FUNDING NUMBERS CNS-1111445 6. AUTHOR(S) Matthew D. Gray 7...Internet Assigned Numbers Authority, there is continued pressure for widespread IPv6 adoption. Because the IPv6 address space is orders of magnitude

  3. Navigating Institutions and Institutional Leadership to Address Sexual Violence

    Sisneros, Kathy; Rivera, Monica

    2018-01-01

    Using an institutional example, this chapter offers strategies to effectively navigate institutional culture, processes, and structures to engage the entire campus community in addressing sexual violence.

  4. Advanced 3-D Ultrasound Imaging: 3-D Synthetic Aperture Imaging using Fully Addressed and Row-Column Addressed 2-D Transducer Arrays

    Bouzari, Hamed

    the important diagnostic information in a noninvasive manner. Diagnostic and therapeutic decisions often require accurate estimates of e.g., organ, cyst, or tumor volumes. 3-D ultrasound imaging can provide these measurements without relying on the geometrical assumptions and operator-dependent skills involved...... is one of the factors for the widespread use of ultrasound imaging. The high price tag on the high quality 3-D scanners is limiting their market share. Row-column addressing of 2-D transducer arrays is a low cost alternative to fully addressed 2-D arrays, for 3-D ultrasound imaging. Using row....... Based on a set of acoustical measurements the center frequency, bandwidth, surface pressure, sensitivity, and acoustical cross-talks were evaluated and discussed. The imaging quality assessments were carried out based on Field II simulations as well as phantom measurements. Moreover, an analysis...

  5. Addressing of LnCaP Cell Using Magnetic Particles Assisted Impedimetric Microelectrode.

    Nguyen, Dung Thi Xuan; Tran, Trong Binh; Nguyen, Phuong-Diem; Min, Junhong

    2016-03-01

    In this study, we provide a facile, effective technique for a simple isolation and enrichment of low metastatic prostate tumor cell LNCaP using biocompatible, magnetic particles asissted impedimetric sensing system. Hydrophobic cell membrane anchors (BAM) were generated onto magnetic particles which diameters vary from 50 nm to 5 μm and were used to capture LNCaP cells from the suspension. Finally, magnetic particle-LNCaP complex were addressed onto the surface of the interdigitated microelectrode (IDM). Cell viability was monitored by our laboratory developed-technique Electrical Cell Substrate Impedance Sensing (ECIS). The results reavealed that 50 nm-magnetic particles showed best performance in terms of cell separation and cell viability. This technique provides a simple and efficient method for the direct addressing of LNCaP cell on the surface and enhances better understanding of cell behavior for cancer management in the near future.

  6. President's Inaugural Address: We Call It School Nursing

    Mattey, Beth

    2015-01-01

    The incoming President of the National Association of School Nurses (NASN) traditionally outlines the theme for their presidency during their inaugural address. This address is given by incoming President of the NASN, Beth Mattey, who discusses previous themes that supported the mission of NASN, but changed every two years with each new president.…

  7. Terms of Address in the Chinese Business Enterprise

    Huang, Xiaoyan; Sultan, Robert

    2014-01-01

    This study examines terms of address currently used by employees of Chinese business enterprises. The authors find that a speaker's address selections are related significantly to the gender of the speaker, the location of the enterprise in Eastern or Western China, and the ownership type of the enterprise; that is, whether the enterprise is…

  8. CIRM Alpha Stem Cell Clinics: Collaboratively Addressing Regenerative Medicine Challenges.

    Jamieson, Catriona H M; Millan, Maria T; Creasey, Abla A; Lomax, Geoff; Donohoe, Mary E; Walters, Mark C; Abedi, Mehrdad; Bota, Daniela A; Zaia, John A; Adams, John S

    2018-06-01

    The California Institute for Regenerative Medicine (CIRM) Alpha Stem Cell Clinic (ASCC) Network was launched in 2015 to address a compelling unmet medical need for rigorous, FDA-regulated, stem cell-related clinical trials for patients with challenging, incurable diseases. Here, we describe our multi-center experiences addressing current and future challenges. Copyright © 2018 Elsevier Inc. All rights reserved.

  9. The 2012 NCTE Presidential Address: Literacy, Rhetoric, Education, Democracy

    Gilyard, Keith

    2013-01-01

    This article presents the text of Keith Gilyard's presidential address, delivered at the National Council of Teachers of English (NCTE) Annual Convention in Las Vegas, Nevada, on November 18, 2012. In his address he proposes several core elements that he believes will instrumentally improve the education system in the United States: a rich…

  10. 75 FR 11610 - Notice Announcing Addresses for Service of Process

    2010-03-11

    ... SOCIAL SECURITY ADMINISTRATION [Docket No. SSA-2009-0076] Notice Announcing Addresses for Service of Process AGENCY: Social Security Administration. ACTION: Notice announcing addresses for summonses and complaints. SUMMARY: The Office of the General Counsel (OGC) is responsible for processing and...

  11. Design and Implementation of High Performance Content-Addressable Memories.

    1985-12-01

    content addressability and two basic implementations of content addressing. The need and application of hardware CAM is presented to motivate the " topic...3r Pass 4th Ps4 Pass Figure 2.15 Maximum SearchUsing All-Parallel CAM - left-most position (the most significant bit) and the other IF bits are zeros

  12. 15 CFR 748.2 - Obtaining forms; mailing addresses.

    2010-01-01

    ... 15 Commerce and Foreign Trade 2 2010-01-01 2010-01-01 false Obtaining forms; mailing addresses... APPLICATIONS (CLASSIFICATION, ADVISORY, AND LICENSE) AND DOCUMENTATION § 748.2 Obtaining forms; mailing addresses. (a) You may obtain the forms required by the EAR from any U.S. Department of Commerce District...

  13. Chair's Address: Voices of the Company We Keep

    Anokye, Akua Duku

    2007-01-01

    This article presents a written version of the address Akua Duku Anokye, chairwoman of the Conference on College Composition and Communication (CCCC), gave at the CCCC meeting in New York on March 24, 2007. In her address, Anokye talked about the importance of how an entity or an individual is known by the company they keep. To learn with whom has…

  14. The "Depreciation" and "Appreciation" of Some Address Terms in China.

    Zhucheng, Ju

    1991-01-01

    Examines how the cultural revolution in China has changed, to some extent, the rules governing the use of address terms, discussing the close interrelation between the use of address terms and cultural values and how the change in mental outlook has led to the depreciation or appreciation of certain terms. (Author/CB)

  15. Student Perceptions of Peer Credibility Based on Email Addresses

    Livermore, Jeffrey A.; Scafe, Marla G.; Wiechowski, Linda S.; Maier, David J.

    2013-01-01

    The purpose of this study was to evaluate students' perceptions of their peer's credibility based on email addresses. The survey was conducted at a community college in Michigan where all students were registered and actively taking at least one course. The survey results show that a student's selection of an email address does influence other…

  16. Faculty Perceptions of Student Credibility Based on Email Addresses

    Livermore, Jeffrey A.; Wiechowski, Linda S.; Scafe, Marla G.

    2011-01-01

    The purpose of this study was to evaluate faculty perceptions of student credibility based on email addresses. The survey was conducted at an upper division business school in Michigan where all students have completed at least two years of college courses. The survey results show that a student's selection of an email address does influence the…

  17. Student Perceptions of Faculty Credibility Based on Email Addresses

    Livermore, Jeffrey A.; Scafe, Marla G.; Wiechowski, Linda S.

    2010-01-01

    The purpose of this study was to evaluate students' perceptions of faculty credibility based on email addresses. The survey was conducted at an upper division business school in Michigan where all students have completed at least two years of college courses. The survey results show that a faculty member's selection of an email address does…

  18. 27 CFR 4.35 - Name and address.

    2010-04-01

    ... named winery: (A) Fermented not less than 75% of such wine at the stated address, or (B) Changed the.... (iv) Blended means that the named winery mixed the wine with other wines of the same class and type at the stated address. (v) Cellared, Vinted or Prepared means that the named winery, at the stated...

  19. 75 FR 3977 - Addressing Tax Delinquency by Government Contractors

    2010-01-25

    ... Part II The President Memorandum of January 20, 2010--Addressing Tax Delinquency by Government... of January 20, 2010 Addressing Tax Delinquency by Government Contractors Memorandum for the Heads of... contracts are awarded to tens of thousands of companies with serious tax delinquencies. The total amount in...

  20. 17 CFR 12.3 - Business address; hours.

    2010-04-01

    ... REPARATIONS General Information and Preliminary Consideration of Pleadings § 12.3 Business address; hours. The... 17 Commodity and Securities Exchanges 1 2010-04-01 2010-04-01 false Business address; hours. 12.3..., DC 20581. It is open each day, except Saturdays, Sundays, and legal public holidays, from 8:15 a.m...

  1. JEREMIAD FRAMES IN REAGAN’S INAUGURAL ADDRESSES

    Mister Gidion Maru

    2013-04-01

    Full Text Available This research attempts to examine the existence of frames from jeremiad tradition as part of American values in an American president’s inaugural address. The function and context of the frames are also investigated. These aims are achieved by applying Goffman’s Frame Analysis on the text of Reagan’s inaugural addresses. This inaugural addresses is chosen because Reagan’s presidency is regarded to set the tone for the following presidencies; his presidency faced crises which other presidents following him have also faced; and he is viewed as one of the best orators among American presidents. The results show that Ronald Reagan’s inaugural addresses use the jeremiad frames which are categorized into three forms, namely, the lamentation of the present, the evocation of the past and the calling for renewal. By using these frames in combination with the context of the inaugural address, Reagan presents American perspective and hopes for their situation and future.

  2. Memory Compression Techniques for Network Address Management in MPI

    Guo, Yanfei; Archer, Charles J.; Blocksome, Michael; Parker, Scott; Bland, Wesley; Raffenetti, Ken; Balaji, Pavan

    2017-05-29

    MPI allows applications to treat processes as a logical collection of integer ranks for each MPI communicator, while internally translating these logical ranks into actual network addresses. In current MPI implementations the management and lookup of such network addresses use memory sizes that are proportional to the number of processes in each communicator. In this paper, we propose a new mechanism, called AV-Rankmap, for managing such translation. AV-Rankmap takes advantage of logical patterns in rank-address mapping that most applications naturally tend to have, and it exploits the fact that some parts of network address structures are naturally more performance critical than others. It uses this information to compress the memory used for network address management. We demonstrate that AV-Rankmap can achieve performance similar to or better than that of other MPI implementations while using significantly less memory.

  3. Single-molecule Mapping of Long-range Electron Transfer for a Cytochrome b562 Variant

    Della Pia, Eduardo Antonio; Chi, Qijin; Jones, D. Dafydd

    2011-01-01

    Cytochrome b562 was engineered to introduce a cysteine residue at a surface-exposed position to facilitate direct self-assembly on a Au(111) surface. The confined protein exhibited reversible and fast electron exchange with a gold substrate over a distance of 20 Å between the heme redox center an...

  4. Duplicate Address Detection Table in IPv6 Mobile Networks

    Alisherov, Farkhod; Kim, Taihoon

    In IP networks, each computer or communication equipment needs an IP address. To supply enough IP addresses, the new Internet protocol IPv6 is used in next generatoion mobile communication. Although IPv6 improves the existing IPv4 Internet protocol, Duplicate Address Detection (DAD) mechanism may consume resources and suffer from long delay. DAD is used to ensure whether the IP address is unique or not. When a mobile node performs an inter-domain handoff, it will first generate a new IP and perform a DAD procedure. The DAD procedure not only wastes time but also increases the signaling load on Internet. In this paper, the author proposes a new DAD mechanism to speed up the DAD procedure. A DAD table is created in access or mobility routers in IP networks and record all IP addresses of the area. When a new IP address needs to perform DAD, it can just search in the DAD table to confirm the uniqueness of the address.

  5. A Quantum Annealing Computer Team Addresses Climate Change Predictability

    Halem, M. (Principal Investigator); LeMoigne, J.; Dorband, J.; Lomonaco, S.; Yesha, Ya.; Simpson, D.; Clune, T.; Pelissier, C.; Nearing, G.; Gentine, P.; hide

    2016-01-01

    The near confluence of the successful launch of the Orbiting Carbon Observatory2 on July 2, 2014 and the acceptance on August 20, 2015 by Google, NASA Ames Research Center and USRA of a 1152 qubit D-Wave 2X Quantum Annealing Computer (QAC), offered an exceptional opportunity to explore the potential of this technology to address the scientific prediction of global annual carbon uptake by land surface processes. At UMBC,we have collected and processed 20 months of global Level 2 light CO2 data as well as fluorescence data. In addition we have collected ARM data at 2sites in the US and Ameriflux data at more than 20 stations. J. Dorband has developed and implemented a multi-hidden layer Boltzmann Machine (BM) algorithm on the QAC. Employing the BM, we are calculating CO2 fluxes by training collocated OCO-2 level 2 CO2 data with ARM ground station tower data to infer to infer measured CO2 flux data. We generate CO2 fluxes with a regression analysis using these BM derived weights on the level 2 CO2 data for three Ameriflux sites distinct from the ARM stations. P. Gentine has negotiated for the access of K34 Ameriflux data in the Amazon and is applying a neural net to infer the CO2 fluxes. N. Talik validated the accuracy of the BM performance on the QAC against a restricted BM implementation on the IBM Softlayer Cloud with the Nvidia co-processors utilizing the same data sets. G. Nearing and K. Harrison have extended the GSFC LIS model with the NCAR Noah photosynthetic parameterization and have run a 10 year global prediction of the net ecosystem exchange. C. Pellisier is preparing a BM implementation of the Kalman filter data assimilation of CO2 fluxes. At UMBC, R. Prouty is conducting OSSE experiments with the LISNoah model on the IBM iDataPlex to simulate the impact of CO2 fluxes to improve the prediction of global annual carbon uptake. J. LeMoigne and D. Simpson have developed a neural net image registration system that will be used for MODIS ENVI and will be

  6. Universality in Oxygen Reduction Electrocatalysis on Metal Surfaces

    Viswanathan, Venkatasubramanian; Hansen, Heine Anton; Rossmeisl, Jan

    2012-01-01

    In this work, we extend the activity volcano for oxygen reduction from the face-centered cubic (fcc) metal (111) facet to the (100) facet. Using density functional theory calculations, we show that the recent findings of constant scaling between OOH* and OH* holds on the fcc metal (100) facet......, as well. Using this fact, we show the existence of a universal activity volcano to describe oxygen reduction electrocatalysis with a minimum overpotential, ηmin = 0.37 ± 0.1 V. Specifically, we find that the (100) facet of Pt is found to bind oxygen intermediates too strongly and is not active for oxygen...... reduction reaction (ORR). In contrast, Au(100) is predicted to be more active than Au(111) and comparable in activity to Pt alloys. Using this activity volcano, we further predict that Au alloys that bind OH more strongly could display improved ORR activity on the (100) facet. We carry out a computational...

  7. IPv6 Addressing Proxy: Mapping Native Addressing from Legacy Technologies and Devices to the Internet of Things (IPv6

    Peter Kirstein

    2013-05-01

    Full Text Available Sensors utilize a large number of heterogeneous technologies for a varied set of application environments. The sheer number of devices involved requires that this Internet be the Future Internet, with a core network based on IPv6 and a higher scalability in order to be able to address all the devices, sensors and things located around us. This capability to connect through IPv6 devices, sensors and things is what is defining the so-called Internet of Things (IoT. IPv6 provides addressing space to reach this ubiquitous set of sensors, but legacy technologies, such as X10, European Installation Bus (EIB, Controller Area Network (CAN and radio frequency ID (RFID from the industrial, home automation and logistic application areas, do not support the IPv6 protocol. For that reason, a technique must be devised to map the sensor and identification technologies to IPv6, thus allowing homogeneous access via IPv6 features in the context of the IoT. This paper proposes a mapping between the native addressing of each technology and an IPv6 address following a set of rules that are discussed and proposed in this work. Specifically, the paper presents a technology-dependent IPv6 addressing proxy, which maps each device to the different subnetworks built under the IPv6 prefix addresses provided by the internet service provider for each home, building or user. The IPv6 addressing proxy offers a common addressing environment based on IPv6 for all the devices, regardless of the device technology. Thereby, this offers a scalable and homogeneous solution to interact with devices that do not support IPv6 addressing. The IPv6 addressing proxy has been implemented in a multi-protocol Sensors 2013, 13 6688 card and evaluated successfully its performance, scalability and interoperability through a protocol built over IPv6.

  8. IPv6 Addressing Proxy: Mapping Native Addressing from Legacy Technologies and Devices to the Internet of Things (IPv6)

    Jara, Antonio J.; Moreno-Sanchez, Pedro; Skarmeta, Antonio F.; Varakliotis, Socrates; Kirstein, Peter

    2013-01-01

    Sensors utilize a large number of heterogeneous technologies for a varied set of application environments. The sheer number of devices involved requires that this Internet be the Future Internet, with a core network based on IPv6 and a higher scalability in order to be able to address all the devices, sensors and things located around us. This capability to connect through IPv6 devices, sensors and things is what is defining the so-called Internet of Things (IoT). IPv6 provides addressing space to reach this ubiquitous set of sensors, but legacy technologies, such as X10, European Installation Bus (EIB), Controller Area Network (CAN) and radio frequency ID (RFID) from the industrial, home automation and logistic application areas, do not support the IPv6 protocol. For that reason, a technique must be devised to map the sensor and identification technologies to IPv6, thus allowing homogeneous access via IPv6 features in the context of the IoT. This paper proposes a mapping between the native addressing of each technology and an IPv6 address following a set of rules that are discussed and proposed in this work. Specifically, the paper presents a technology-dependent IPv6 addressing proxy, which maps each device to the different subnetworks built under the IPv6 prefix addresses provided by the internet service provider for each home, building or user. The IPv6 addressing proxy offers a common addressing environment based on IPv6 for all the devices, regardless of the device technology. Thereby, this offers a scalable and homogeneous solution to interact with devices that do not support IPv6 addressing. The IPv6 addressing proxy has been implemented in a multi-protocol card and evaluated successfully its performance, scalability and interoperability through a protocol built over IPv6. PMID:23686145

  9. IPv6 addressing proxy: mapping native addressing from legacy technologies and devices to the Internet of Things (IPv6).

    Jara, Antonio J; Moreno-Sanchez, Pedro; Skarmeta, Antonio F; Varakliotis, Socrates; Kirstein, Peter

    2013-05-17

    Sensors utilize a large number of heterogeneous technologies for a varied set of application environments. The sheer number of devices involved requires that this Internet be the Future Internet, with a core network based on IPv6 and a higher scalability in order to be able to address all the devices, sensors and things located around us. This capability to connect through IPv6 devices, sensors and things is what is defining the so-called Internet of Things (IoT). IPv6 provides addressing space to reach this ubiquitous set of sensors, but legacy technologies, such as X10, European Installation Bus (EIB), Controller Area Network (CAN) and radio frequency ID (RFID) from the industrial, home automation and logistic application areas, do not support the IPv6 protocol. For that reason, a technique must be devised to map the sensor and identification technologies to IPv6, thus allowing homogeneous access via IPv6 features in the context of the IoT. This paper proposes a mapping between the native addressing of each technology and an IPv6 address following a set of rules that are discussed and proposed in this work. Specifically, the paper presents a technology-dependent IPv6 addressing proxy, which maps each device to the different subnetworks built under the IPv6 prefix addresses provided by the internet service provider for each home, building or user. The IPv6 addressing proxy offers a common addressing environment based on IPv6 for all the devices, regardless of the device technology. Thereby, this offers a scalable and homogeneous solution to interact with devices that do not support IPv6 addressing. The IPv6 addressing proxy has been implemented in a multi-protocol Sensors 2013, 13 6688 card and evaluated successfully its performance, scalability and interoperability through a protocol built over IPv6.

  10. Address Points, The Address Point layer contains an address point for almost every structure over 200 square feet and for some vacant properties. Attributes include addresses, sub-units, address use, LAT/LONG, 10-digit SDAT taxpins, political areas and more., Published in 2013, 1:2400 (1in=200ft) scale, Baltimore County Government.

    NSGIC Local Govt | GIS Inventory — Address Points dataset current as of 2013. The Address Point layer contains an address point for almost every structure over 200 square feet and for some vacant...

  11. Surface mining

    Robert Leopold; Bruce Rowland; Reed Stalder

    1979-01-01

    The surface mining process consists of four phases: (1) exploration; (2) development; (3) production; and (4) reclamation. A variety of surface mining methods has been developed, including strip mining, auger, area strip, open pit, dredging, and hydraulic. Sound planning and design techniques are essential to implement alternatives to meet the myriad of laws,...

  12. Superhydrophobic surfaces

    Wang, Evelyn N; McCarthy, Matthew; Enright, Ryan; Culver, James N; Gerasopoulos, Konstantinos; Ghodssi, Reza

    2015-03-24

    Surfaces having a hierarchical structure--having features of both microscale and nanoscale dimensions--can exhibit superhydrophobic properties and advantageous condensation and heat transfer properties. The hierarchical surfaces can be fabricated using biological nanostructures, such as viruses as a self-assembled nanoscale template.

  13. Surface characterization

    Mandla A. Tshabalala

    2005-01-01

    Surface properties of wood play an important role when wood is used or processed into different commodities such as siding, joinery, textiles, paper, sorption media or wood composites. Thus, for example, the quality and durability of a wood coating are determined by the surface properties of the wood and the coating. The same is true for wood composites, as the...

  14. 27 CFR 7.25 - Name and address.

    2010-04-01

    ... false or misleading impression as to the geographic origin of the beer. (2) If malt beverages are... address in connection with the particular malt beverage. (Approved by the Office of Management and Budget...

  15. Addressing obesity in South Africa through taxation | IDRC ...

    2016-11-17

    Nov 17, 2016 ... The same tax can reduce diabetes prevalence in adults by 4%, and incident ... are only one component of a multi-pronged strategy to address obesity. ... and regulating food labelling, advertising, and marketing to reduce ...

  16. Police and Community-partnered Delivery System to Address ...

    ... Delivery System to Address Violence Against Women in the Punjab (India) ... Education, Scheduled Castes and Other Back Classes, and Land Rural Development. ... IWRA/IDRC webinar on climate change and adaptive water management.

  17. Son Preference in China and India : Policy Interventions to address ...

    ... form, at its most extreme shifting from female infanticide to sex-selective abortion. Both countries have enacted laws to combat gender-based discrimination in ... in China and India that have attempted to address discrimination against girls.

  18. Addressing Software Engineering Issues in Real-Time Software ...

    Addressing Software Engineering Issues in Real-Time Software ... systems, manufacturing process, process control, military, space exploration, and ... but also physical properties such as timeliness, Quality of Service and reliability.

  19. Toward Addressing Skills Development and Employment Crisis in ...

    Toward Addressing Skills Development and Employment Crisis in Uganda: ... women and youth - both educated and uneducated - and key informants, ... skills development are explored from countries like, Singapore, Malaysia, and Mauritius.

  20. The potential of capstone learning experiences in addressing ...

    The potential of capstone learning experiences in addressing perceived shortcomings in LLB training in South Africa. ... A literature review on capstone courses and learning experiences (collectively referred to ... AJOL African Journals Online.

  1. BCB polymer based row-column addressed CMUT

    Havreland, Andreas Spandet; Ommen, Martin Lind; Silvestre, Chantal

    2017-01-01

    This paper presents an inexpensive, low temperature and rapid fabrication method for capacitive micromachined ultrasonic transducers (CMUT). The fabrication utilizes the bonding and dielectric properties of the photosensitive polymer Benzocyclobutene (BCB). A BCB based row-column addressed CMUT w...

  2. Find Shortage Areas: HPSA & MUA/P by Address

    U.S. Department of Health & Human Services — The Find Shortage Areas: Health Professional Shortage Area (HPSA) and Medically Underserved Area/Population (MUA/P) by Address tool helps you determine if a specific...

  3. Framework for supporting countries to address the food crisis and ...

    Framework for supporting countries to address the food crisis and malnutrition in the African region. ... African Journal of Food, Agriculture, Nutrition and Development ... Protection of vulnerable groups; and Evidence- based interventions.

  4. Addressable droplet microarrays for single cell protein analysis.

    Salehi-Reyhani, Ali; Burgin, Edward; Ces, Oscar; Willison, Keith R; Klug, David R

    2014-11-07

    Addressable droplet microarrays are potentially attractive as a way to achieve miniaturised, reduced volume, high sensitivity analyses without the need to fabricate microfluidic devices or small volume chambers. We report a practical method for producing oil-encapsulated addressable droplet microarrays which can be used for such analyses. To demonstrate their utility, we undertake a series of single cell analyses, to determine the variation in copy number of p53 proteins in cells of a human cancer cell line.

  5. Positional error in automated geocoding of residential addresses

    Talbot Thomas O

    2003-12-01

    Full Text Available Abstract Background Public health applications using geographic information system (GIS technology are steadily increasing. Many of these rely on the ability to locate where people live with respect to areas of exposure from environmental contaminants. Automated geocoding is a method used to assign geographic coordinates to an individual based on their street address. This method often relies on street centerline files as a geographic reference. Such a process introduces positional error in the geocoded point. Our study evaluated the positional error caused during automated geocoding of residential addresses and how this error varies between population densities. We also evaluated an alternative method of geocoding using residential property parcel data. Results Positional error was determined for 3,000 residential addresses using the distance between each geocoded point and its true location as determined with aerial imagery. Error was found to increase as population density decreased. In rural areas of an upstate New York study area, 95 percent of the addresses geocoded to within 2,872 m of their true location. Suburban areas revealed less error where 95 percent of the addresses geocoded to within 421 m. Urban areas demonstrated the least error where 95 percent of the addresses geocoded to within 152 m of their true location. As an alternative to using street centerline files for geocoding, we used residential property parcel points to locate the addresses. In the rural areas, 95 percent of the parcel points were within 195 m of the true location. In suburban areas, this distance was 39 m while in urban areas 95 percent of the parcel points were within 21 m of the true location. Conclusion Researchers need to determine if the level of error caused by a chosen method of geocoding may affect the results of their project. As an alternative method, property data can be used for geocoding addresses if the error caused by traditional methods is

  6. Addressable-Matrix Integrated-Circuit Test Structure

    Sayah, Hoshyar R.; Buehler, Martin G.

    1991-01-01

    Method of quality control based on use of row- and column-addressable test structure speeds collection of data on widths of resistor lines and coverage of steps in integrated circuits. By use of straightforward mathematical model, line widths and step coverages deduced from measurements of electrical resistances in each of various combinations of lines, steps, and bridges addressable in test structure. Intended for use in evaluating processes and equipment used in manufacture of application-specific integrated circuits.

  7. 27 CFR 46.126 - Change in name or address.

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 2 2010-04-01 2010-04-01 false Change in name or address... (occupational) Tax Stamps § 46.126 Change in name or address. (a) Change in name. If there is a change in the corporate or firm name, or in the trade name, as shown on TTB Form 5630.5t, the taxpayer must file an...

  8. THE PRAGMATIC MEANINGS OF ADDRESS TERMS SAMPEYAN AND ANDA

    Djoko Susanto

    2014-07-01

    Full Text Available Abstract: This research investigates the use of sampeyan and anda by the students from Pasuruan and Probolinggo. Address terms is one of important tools in communication in Javanese society as it is used, for example, to designate the person they are talking to or to show the possession of formal and informal manners. However, the use of this address terms may have different interpretation across regions. This research is undertaken to find out (1 factors that influence the choice of address terms sampeyan and anda in Pasuruan and Probolinggo and (2 situations in which the interlocutors use the address terms sampeyan and anda. Several theories are used to help analyze the data, which include address terms (Wardhaugh, 2002, sampeyan and anda (Wolf & Poedjosoedarmo, 1982, Politeness theory (Brown & Levinson, 1987, and Power and Solidarity (Brown & Gilman, 1960. The data were obtained from the results of observations, questionnaires and interviews with the participants. The results of the study show that both sampeyan and anda were found to be commonly used by the participants to address their lecturer, instead of using Bapak. This is, of course, uncommon from either the perspective of standard usage of Javanese or Indonesian language. This study also indicates that the participants used sampeyan to lecturer/teacher, kyai, parent, and older sibling because they wanted to express (1 express politeness and (2 to indicate informality. Concerning to the use of anda, this study reveals that the participants use this address term because of (1 more formal and appropriate manners in environmental education, (2 respecting person of higher social status and older person, (3 more polite and more appropriate than sampeyan, and (4 the use of Indonesian as a formal language. In some respect, however, the participants use anda to lecturer/teacher, which is not appropriate because they were not socially equal to the lecturer/teacher.  This study provide

  9. Surface layer temperature inversion in the Bay of Bengal

    Pankajakshan, T.; Gopalakrishna, V.V.; Muraleedharan, P.M.; Reddy, G.V.; Araligidad, N.; Shenoy, Shrikant

    Surface layer temperature inversion occurring in the Bay of Bengal has been addressed. Hydrographic data archived in the Indian Oceanographic Data Center are used to understand various aspects of the temperature inversion of surface layer in the Bay...

  10. Automated Hybrid Microwave Heating for Lunar Surface Solidification, Phase I

    National Aeronautics and Space Administration — This SBIR project addresses the need for a system that will provide automated lunar surface stabilization via hybrid microwave heating. Surface stabilization is...

  11. Surface Habitat Systems

    Kennedy, Kriss J.

    2009-01-01

    The Surface Habitat Systems (SHS) Focused Investment Group (FIG) is part of the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC) effort to provide a focused direction and funding to the various projects that are working on human surface habitat designs and technologies for the planetary exploration missions. The overall SHS-FIG effort focuses on directing and guiding those projects that: 1) develop and demonstrate new surface habitat system concepts, innovations, and technologies to support human exploration missions, 2) improve environmental systems that interact with human habitats, 3) handle and emplace human surface habitats, and 4) focus on supporting humans living and working in habitats on planetary surfaces. The activity areas of the SHS FIG described herein are focused on the surface habitat project near-term objectives as described in this document. The SHS-FIG effort focuses on mitigating surface habitat risks (as identified by the Lunar Surface Systems Project Office (LSSPO) Surface Habitat Element Team; and concentrates on developing surface habitat technologies as identified in the FY08 gap analysis. The surface habitat gap assessment will be updated annually as the surface architecture and surface habitat definition continues to mature. These technologies are mapped to the SHS-FIG Strategic Development Roadmap. The Roadmap will bring to light the areas where additional innovative efforts are needed to support the development of habitat concepts and designs and the development of new technologies to support of the LSSPO Habitation Element development plan. Three specific areas of development that address Lunar Architecture Team (LAT)-2 and Constellation Architecture Team (CxAT) Lunar habitat design issues or risks will be focused on by the SHS-FIG. The SHS-FIG will establish four areas of development that will help the projects prepare in their planning for surface habitat systems development. Those development areas are

  12. Convex surfaces

    Busemann, Herbert

    2008-01-01

    This exploration of convex surfaces focuses on extrinsic geometry and applications of the Brunn-Minkowski theory. It also examines intrinsic geometry and the realization of intrinsic metrics. 1958 edition.

  13. Surface boxplots

    Genton, Marc G.

    2014-01-22

    In this paper, we introduce a surface boxplot as a tool for visualization and exploratory analysis of samples of images. First, we use the notion of volume depth to order the images viewed as surfaces. In particular, we define the median image. We use an exact and fast algorithm for the ranking of the images. This allows us to detect potential outlying images that often contain interesting features not present in most of the images. Second, we build a graphical tool to visualize the surface boxplot and its various characteristics. A graph and histogram of the volume depth values allow us to identify images of interest. The code is available in the supporting information of this paper. We apply our surface boxplot to a sample of brain images and to a sample of climate model outputs.

  14. Surface boxplots

    Genton, Marc G.; Johnson, Christopher; Potter, Kristin; Stenchikov, Georgiy L.; Sun, Ying

    2014-01-01

    In this paper, we introduce a surface boxplot as a tool for visualization and exploratory analysis of samples of images. First, we use the notion of volume depth to order the images viewed as surfaces. In particular, we define the median image. We use an exact and fast algorithm for the ranking of the images. This allows us to detect potential outlying images that often contain interesting features not present in most of the images. Second, we build a graphical tool to visualize the surface boxplot and its various characteristics. A graph and histogram of the volume depth values allow us to identify images of interest. The code is available in the supporting information of this paper. We apply our surface boxplot to a sample of brain images and to a sample of climate model outputs.

  15. Surface channeling

    Sizmann, R.; Varelas, C.

    1976-01-01

    There is experimental evidence that swift light ions incident at small angles towards single crystalline surfaces can lose an appreciable fraction of their kinetic energy during reflection. It is shown that these projectiles penetrate into the bulk surface region of the crystal. They can travel as channeled particles along long paths through the solid (surface channeling). The angular distribution and the depth history of the re-emerged projectiles are investigated by computer simulations. A considerable fraction of the penetrating projectiles re-emerges from the crystal with constant transverse energy if the angle of incidence is smaller than the critical angle for axial channeling. Analytical formulae are derived based on a diffusion model for surface channeling. A comparison with experimental data exhibits the relevance of the analytical solutions. (Auth.)

  16. Martian surface

    Carr, M.H.

    1987-01-01

    The surface of Mars is characterized on the basis of reformatted Viking remote-sensing data, summarizing results published during the period 1983-1986. Topics examined include impact craters, ridges and faults, volcanic studies (modeling of surface effects on volcanic activity, description and interpretation of volcanic features, and calculations on lava-ice interactions), the role of liquid water on Mars, evidence for abundant ground ice at high latitudes, water-cycle modeling, and the composition and dynamics of Martian dust

  17. Surface decontamination

    Silva, S. da; Teixeira, M.V.

    1986-06-01

    The general methods of surface decontamination used in laboratory and others nuclear installations areas, as well as the procedures for handling radioactive materials and surfaces of work are presented. Some methods for decontamination of body external parts are mentioned. The medical supervision and assistance are required for internal or external contamination involving or not lesion in persons. From this medical radiation protection decontamination procedures are determined. (M.C.K.) [pt

  18. Surface phonons

    Wette, Frederik

    1991-01-01

    In recent years substantial progress has been made in the detection of surface phonons owing to considerable improvements in inelastic rare gas scattering tech­ niques and electron energy loss spectroscopy. With these methods it has become possible to measure surface vibrations in a wide energy range for all wave vectors in the two-dimensional Brillouin zone and thus to deduce the complete surface phonon dispersion curves. Inelastic atomic beam scattering and electron energy loss spectroscopy have started to play a role in the study of surface phonons similar to the one played by inelastic neutron scattering in the investigation of bulk phonons in the last thirty years. Detailed comparison between experimen­ tal results and theoretical studies of inelastic surface scattering and of surface phonons has now become feasible. It is therefore possible to test and to improve the details of interaction models which have been worked out theoretically in the last few decades. At this point we felt that a concise, co...

  19. A diagonal address generator for a Josephson memory circuit

    Suzuki, H.; Hasuo, S.

    1987-01-01

    The authors propose that a diagonal D address generator, which is useful for a single flux quantum (SFQ) memory cell in the triple coincidence scheme, can be performed by a full adder circuit. For the purpose of evaluating the D address generator for a 16-kbit memory circuit, a 6-bit full adder circuit, using a current-steering flip-flop circuit, has been designed and fabricated with the lead-alloy process. Operating times for the address latch, carry generator, and sum generator were 150 ps, 250 ps/stage, and 1.4 ns, respectively. From these results, they estimate that the time necessary for the diagonal signal generation is 2.8 ns

  20. Wind versus Biofuels for Addressing Climate, Health, and Energy

    Jacobson, Mark Z.

    2007-01-01

    The favored approach today for addressing global warming is to promote a variety of options: biofuels, wind, solar thermal, solar photovoltaic, geothermal, hydroelectric, and nuclear energy and to improve efficiency. However, by far, most emphasis has been on biofuels. It is shown here, though, that current-technology biofuels cannot address global warming and may slightly increase death and illness due to ozone-related air pollution. Future biofuels may theoretically slow global warming, but only temporarily and with the cost of increased air pollution mortality. In both cases, the land required renders biofuels an impractical solution. Recent measurements and statistical analyses of U.S. and world wind power carried out at Stanford University suggest that wind combined with other options can substantially address global warming, air pollution mortality, and energy needs simultaneously.

  1. Firewall for Dynamic IP Address in Mobile IPv6

    Qiu, Ying; Bao, Feng; Zhou, Jianying

    Mobile communication is becoming the mainstream with the rapid growth of mobile devices penetrating our daily life. More and more mobile devices such as mobile phones, personal digital assistants, notebooks etc, are capable of Internet access. Mobile devices frequently change their communication IP addresses in mobile IPv6 network following its current attached domain. This raises a big challenge for building firewall for mobile devices. The conventional firewalls are primarily based on IPv4 networks where the security criteria are specified only to the fixed IP addresses or subnets, which apparently do not apply to mobile IPv6. In this paper we propose three solutions for mobile IPv6 firewall. Our approaches make the firewall adaptive to dynamic IP addresses in mobile IPv6 network. They have different expense and weight corresponding to different degree of universality. The paper focuses the study more from practical aspect.

  2. Big data, little security: Addressing security issues in your platform

    Macklin, Thomas; Mathews, Joseph

    2017-05-01

    This paper describes some patterns for information security problems that consistently emerge among traditional enterprise networks and applications, both with respect to cyber threats and data sensitivity. We draw upon cases from qualitative studies and interviews of system developers, network operators, and certifiers of military applications. Specifically, the problems discussed involve sensitivity of data aggregates, training efficacy, and security decision support in the human machine interface. While proven techniques can address many enterprise security challenges, we provide additional recommendations on how to further improve overall security posture, and suggest additional research thrusts to address areas where known gaps remain.

  3. Addressing resistance to antibiotics in systematic reviews of antibiotic interventions

    Leibovici, Leonard; Paul, Mical; Garner, Paul

    2016-01-01

    Antibiotics are among the most important interventions in healthcare. Resistance of bacteria to antibiotics threatens the effectiveness of treatment. Systematic reviews of antibiotic treatments often do not address resistance to antibiotics even when data are available in the original studies....... This omission creates a skewed view, which emphasizes short-term efficacy and ignores the long-term consequences to the patient and other people. We offer a framework for addressing antibiotic resistance in systematic reviews. We suggest that the data on background resistance in the original trials should...... controlled trials or systematic reviews....

  4. Addressing chronic operational issues at the W. M. Keck Observatory

    Nordin, Tom; Matsuda, Richard

    2016-07-01

    The W. M. Keck Observatory (WMKO) has a good track record at addressing large critical faults which impact observing. Our performance tracking and correcting chronic minor faults has been mixed, yet this class of problems has a significant negative impact on scientific productivity and staff effectiveness. We have taken steps to address this shortcoming. This paper outlines the creation of a program to identify, categorize and rank these chronic operational issues, track them over time, and develop management options for their resolution. The success of the program at identifying these chronic operational issues and the advantages of dedicating observatory resources to this endeavor are presented.

  5. A Novel Smart Meter Controlling System with Dynamic IP Addresses

    Manembu, Pinrolinvic; Welang, Brammy; Kalua Lapu, Aditya

    2017-01-01

    Smart meters are the electronic devices for measuring energy consumption in real time. Usually, static public IP addresses are allocated to realize the point-to-point (P2P) communication and remote controlling for smart metering systems. This, however, restricts the wide deployment of smart meters......, due to the deficiency of public IP resources. This paper proposes a novel subscription-based communication architecture for the support of dynamic IP addresses and group controlling of smart meters. The paper evaluates the proposed architecture by comparing the traditional P2P architecture...

  6. Mapping of MAC Address with Moving WiFi Scanner

    Arief Hidayat

    2017-10-01

    Full Text Available Recently, Wifi is one of the most useful technologies that can be used for detecting and counting MAC Address. This paper described using of WiFi scanner which carried out seven times circulated the bus. The method used WiFi and GPS are to counting MAC address as raw data from the pedestrian smartphone, bus passenger or WiFi devices near from the bus as long as the bus going around the route. There are seven processes to make map WiFi data.

  7. Residualization is not the answer: Rethinking how to address multicollinearity.

    York, Richard

    2012-11-01

    Here I show that a commonly used procedure to address problems stemming from collinearity and multicollinearity among independent variables in regression analysis, "residualization", leads to biased coefficient and standard error estimates and does not address the fundamental problem of collinearity, which is a lack of information. I demonstrate this using visual representations of collinearity, hypothetical experimental designs, and analyses of both artificial and real world data. I conclude by noting the importance of examining methodological practices to ensure that their validity can be established based on rational criteria. Copyright © 2012 Elsevier Inc. All rights reserved.

  8. Addressing Climate Change and the Role of Technological Solutions

    Stephen Axon

    2010-05-01

    Full Text Available As far as sustainability is concerned, the role of technology has always been contested. With regard to environmental degradation, technology is either perceived to be part of the problem or part of the solution. To combat the complex issues of the present time, technological solutions are expected to play a key role towards mitigating and adapting to the negative impacts of climate change. The paper also discusses the role of the 2009 Copenhagen Conference towards addressing climate change. Although the Copenhagen Accord is not a legally binding agreement, it is seen as a necessary first step towards a protocol that will effectively address the issue of climate change.

  9. Hindered rotation of a copper phthalocyanine molecule on C60 : Experiments and molecular mechanics calculations

    Fendrich, M.; Wagner, Th.; Stöhr, M.; Möller, R.

    2006-01-01

    If copper phthalocyanine (CuPc) molecules are deposited on a Au(111) surface covered with a monolayer of C60, the molecules are found to adsorb individually onto the close-packed layer of C60. As the adsorption site of the CuPc is not symmetric with respect to the underlying C60 layer, the CuPc

  10. Shot noise as a probe of spin-polarized transport through single atoms

    Burtzlaff, Andreas; Weismann, Alexander; Brandbyge, Mads

    2015-01-01

    Single atoms on Au(111) surfaces have been contacted with the Au tip of a low temperature scanning tunneling microscope. The shot noise of the current through these contacts has been measured up to frequencies of 120 kHz and Fano factors have been determined to characterize the transport channels...

  11. Synthesis, molecular structure, spectroscopic investigations and ...

    MS received 29 December 2015; revised 9 April 2016; accepted 25 May 2016 ... B, open form blue. Scheme 1. Structures and Photochromic reaction of the title compound. 2. Experimental. 2.1 Materials and measurements. The mid-IR spectra were obtained in the ... segment is put between two parallel Au(111) surfaces,.

  12. Combination of Scanning Probe Microscopy and Coordination Chemistry: Structural and Electronic Study of Bis(methylbenzimidazolyl)ketone and Its Iron Complex

    Folkertsma, Emma; Van Der Lit, Joost; Di Cicco, Francesca; Lutz, Martin; Klein Gebbink, Robertus J. M.; Swart, Ingmar; Moret, Marc-etienne

    2017-01-01

    Here, we report the bulk synthesis of [FeII(BMBIK)Cl2] bearing the redox noninnocent bis(methylbenzimidazolyl)ketone (BMBIK) ligand and the synthesis of the similar complex [FeI(BMBIK)]+ on a Au(111) surface using lateral manipulation at the atomic level. Cyclic voltammetry and scanning tunneling

  13. Making gold less noble

    Mavrikakis, Manos; Stoltze, Per; Nørskov, Jens Kehlet

    2000-01-01

    Self-consistent density functional calculations for the adsorption of O and CO on flat and stepped Au(111) surfaces are used to investigate effects which may increase the reactivity of Au. We find that the adsorption energy does not depend on the number of Au layers if there are more than two lay...

  14. Hydrogen evolution on nano-particulate transition metal sulfides

    Bonde, Jacob Lindner; Moses, Poul Georg; Jaramillo, Thomas F.

    2008-01-01

    The hydrogen evolution reaction (HER) on carbon supported MoS2 nanoparticles is investigated and compared to findings with previously published work on Au(111) supported MoS2. An investigation into MoS2 oxidation is presented and used to quantify the surface concentration of MoS2. Other metal sul...

  15. Modern techniques of surface science

    Woodruff, D Phil

    2016-01-01

    This fully revised, updated and reorganised third edition provides a thorough introduction to the characterisation techniques used in surface science and nanoscience today. Each chapter brings together and compares the different techniques used to address a particular research question, including how to determine the surface composition, surface structure, surface electronic structure, surface microstructure at different length scales (down to sub-molecular), and the molecular character of adsorbates and their adsorption or reaction properties. Readers will easily understand the relative strengths and limitations of the techniques available to them and, ultimately, will be able to select the most suitable techniques for their own particular research purposes. This is an essential resource for researchers and practitioners performing materials analysis, and for senior undergraduate students looking to gain a clear understanding of the underlying principles and applications of the different characterisation tec...

  16. Predictive Surface Complexation Modeling

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

    2016-11-29

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

  17. Mostly surfaces

    Schwartz, Richard Evan

    2011-01-01

    This book presents a number of topics related to surfaces, such as Euclidean, spherical and hyperbolic geometry, the fundamental group, universal covering surfaces, Riemannian manifolds, the Gauss-Bonnet Theorem, and the Riemann mapping theorem. The main idea is to get to some interesting mathematics without too much formality. The book also includes some material only tangentially related to surfaces, such as the Cauchy Rigidity Theorem, the Dehn Dissection Theorem, and the Banach-Tarski Theorem. The goal of the book is to present a tapestry of ideas from various areas of mathematics in a clear and rigorous yet informal and friendly way. Prerequisites include undergraduate courses in real analysis and in linear algebra, and some knowledge of complex analysis.

  18. Surface rights

    Regina Célia Corrêa Landim

    2009-06-01

    Full Text Available In many cities of Brazil, social inequality is illustrated by violence, poverty, and unemployment located next to luxurious residential towers and armored passenger cars. In the face of this situation, the National Movement of Urban Reform encouraged the inclusion of the social function of property in Brazil's new constitution of 1988. Surface rights represent an urbanistic instrument in the city statute that is best aligned to the constitutional principles and urban policies. The current article compares two laws that govern the principle of surface rights and provides a brief history of the evolution of the state based on illuminism and the consequent change in paradigm affecting individual rights, including property and civil rights, and their interpretation under the Constitution. The article concludes by suggesting the use of land surface rights in a joint operation, matching the ownership of the property with urban planning policies and social interest.

  19. Identifying and Addressing Themes of Job Dissatisfaction for Secondary Principals

    De Jong, David; Grundmeyer, Trent; Yankey, Julie

    2017-01-01

    Secondary principals serve in important roles that are complex, high-stress, and include demanding job responsibilities. Key stakeholders such as superintendents, school board members, and legislators must understand the challenges facing secondary principals in order to address the current themes of job dissatisfaction. Using new survey data…

  20. Addressing sampling bias in counting forest birds: a West African ...

    Addressing sampling bias in counting forest birds: a West African case study. ... result may occur because of the noise they may introduce into the analysis. ... used at all; and for all transects to reach their mid-point at the same time each day, ...

  1. The role of health education in addressing the health divide

    Simovska, Venka

    2013-01-01

    The aim of this chapter is to argue that an approach to health education, consistent with critical education theory echoing Freire’s ideas, has the potential to play a significant role in addressing determinants of health by, first and foremost, providing children and young people with opportunit...

  2. 76 FR 22681 - Defense Logistics Agency (DLA) Address Directory

    2011-04-22

    ... DEPARTMENT OF DEFENSE Office of the Secretary Defense Logistics Agency (DLA) Address Directory AGENCY: Department of Defense. ACTION: Notice. SUMMARY: The Defense Logistics Agency (DLA) is updating... Directory: Defense Logistics Agency Headquarters, Andrew T. McNamara Building, 8725 John J. Kingman Road...

  3. Addressing resistance to antibiotics in systematic reviews of antibiotic interventions

    Leibovici, Leonard; Paul, Mical; Garner, Paul; Sinclair, David J; Afshari, Arash; Pace, Nathan Leon; Cullum, Nicky; Williams, Hywel C; Smyth, Alan; Skoetz, Nicole; Del Mar, Chris; Schilder, Anne G M; Yahav, Dafna; Tovey, David

    Antibiotics are among the most important interventions in healthcare. Resistance of bacteria to antibiotics threatens the effectiveness of treatment. Systematic reviews of antibiotic treatments often do not address resistance to antibiotics even when data are available in the original studies. This

  4. Addressing Anger Using Sensorimotor Psychotherapy and Cognitive Behaviour Therapy

    Flynn, Sarah M.

    2010-01-01

    A young woman initiated counselling services at a community agency to address her explosive anger that was a remnant of childhood physical and emotional abuse. Sensorimotor psychotherapy was used to help this client learn how to monitor and regulate her sensorimotor processes. In conjunction with this approach, Cognitive behavioural therapy was…

  5. Are Teacher and Principal Candidates Prepared to Address Student Cyberbullying?

    Styron, Ronald A., Jr.; Bonner, Jessica L.; Styron, Jennifer L.; Bridgeforth, James; Martin, Cecelia

    2016-01-01

    The purpose of this study was to examine the preparation of teacher and principal candidates to address problems created in K-12 settings as a result of cyberbullying. Participants included teacher and principal preparation students. Findings indicated that respondents were familiar with the most common forms of cyberbullying and its impact on…

  6. Addressing Nature Deficit Disorder through Primitive Camping Experiences

    Allen, Kevin; Varner, Keegan; Sallee, Jeff

    2011-01-01

    Today's youth suffer from Nature Deficit Disorder, a condition that has been connected to ADHD, shortage of creativity, and general lack of knowledge about the outdoors. A team of educators and specialists are addressing this issue with primitive camping. County educators were trained using experiential learning and train-the-trainer techniques.…

  7. Understanding and Addressing Homophobia in Schools: A View from Teachers

    Bhana, Deevia

    2012-01-01

    South African schools have been found to be homophobic. Teachers can play an important role in offering a critique of homophobia grounded in South Africa's legal claim to equality on the basis of sexual orientation. Currently there is a dearth of educational research about how teachers understand and address homophobia. By drawing upon focus-group…

  8. Organizing for Flexibility: Addressing Dynamic Capabilities and Organization Design

    van der Weerdt, Niels; Volberda, Henk; Verwaal, Ernst; Stienstra, Marten

    2014-01-01

    The increasingly dynamic nature of organizational environments has led the research community to study organizational flexibility. Although the research literature stresses the complexity of the organizational flexibility construct, it lacks a comprehensive empirical study addressing the relationships among various dimensions of organizational flexibility. This chapter develops a theoretical framework specifying the linkages between types of flexibility and organization design characteristics...

  9. Addressing the "Epidemic" of Overweight Children by Using the Internet

    Coleman, Mick; Wallinga, Charlotte; Bales, Diane

    2009-01-01

    The Internet can be of great assistance to early childhood teachers in planning educational activities for the classroom and with families. This article explores how early childhood teachers can use resources online to address what has been called an "epidemic" of overweight children. Guidelines for using online resources are presented. (Contains…

  10. Secondary Data Analysis: An Important Tool for Addressing Developmental Questions

    Greenhoot, Andrea Follmer; Dowsett, Chantelle J.

    2012-01-01

    Existing data sets can be an efficient, powerful, and readily available resource for addressing questions about developmental science. Many of the available databases contain hundreds of variables of interest to developmental psychologists, track participants longitudinally, and have representative samples. In this article, the authors discuss the…

  11. Communicating one's local address and emergency contact details

    Information Technology Department, AIS (Administrative Information Services) Group; Human Resources Department, SPS (Services, Procedures and Social) Group

    2007-01-01

    As part of the ongoing simplification of procedures and rationalisation of administrative processes, the IT, PH (Users Office) and HR Departments have developed two new EDH forms for communicating or updating one's local address and emergency contact details. This is the first time that the forms relating to an official HR procedure can be accessed on a self-service basis and directly updated by the members of personnel themselves. The information recorded remains confidential and may only be accessed by the authorised administrative services and the emergency services. Local address: Members of the personnel must declare any change in their local address (Art. R V 1.38 of the Staff Regulations). This declaration is henceforth made by directly filling out the EDH document indicated below, and without requiring any other spontaneous formality vis-à-vis the department secretariat or the Users Office. It is also possible for any member of the personnel to check whether the local address in the Organizati...

  12. Balancing Act: Addressing Culture and Gender in ESL Classrooms

    Johnson, Michelle A.; Chang, Debbie

    2012-01-01

    ESL educators find themselves teaching a diverse group of students in today's classroom. This study investigated how ESL instructors address diversity in their teaching. The literature review revealed research on the experiences of teachers using culturally responsive teaching strategies. Using qualitative research methods, this study explores the…

  13. Reframing "The Italian": Questions of Audience Address in Early Cinema.

    Keil, Charlie

    1990-01-01

    Analyzes "The Italian" (1915), an early "immigrant" film, examining its problematic relation to questions of working-class and middle-class audience composition. Shows how this film reveals that the creation of narratives suitable for diverse audiences requires continuous readjustment of an adequate mode of address. (MM)

  14. Actions States and Communities Can Take to Address Cognitive Health

    2014-06-09

    In this podcast, CDC’s Dr. Lynda Anderson highlights the important roles that states and communities can play in addressing cognitive health as part of overall health.  Created: 6/9/2014 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 6/9/2014.

  15. Responsibility for radical change in addressing climate change

    Bouvrie, des N.; Karlsson-Vinkhuyzen, S.I.S.E.; Jollands, N.

    2015-01-01

    To radically address the problem of climate change, it is not enough to modify specific attitudes and behaviors while upholding the present paradigms. This article aims to show why modifications will never bring about radical carbon emission reductions. We discuss what it implies to desire radical

  16. Catholic Social Teaching: Addressing Globalization in Catholic Business Education

    Ball, James B.; Martinez, Zaida; Toyne, Brian

    2009-01-01

    Although business schools are increasingly aware of the importance of globalization in educating future business leaders, their business programs have addressed globalization from a limited perspective that fails to provide students with a broader understanding of its impact on societies and its moral consequences. The conventional approach to the…

  17. Maryland's Model Policy to Address Bullying, Harassment, or Intimidation

    Maryland State Department of Education, 2016

    2016-01-01

    In accordance with the provisions of Section 7-424.1 of the Education Article of the Annotated Code of Maryland, the Maryland State Board of Education has developed and adopted a Model Policy to address bullying, harassment, or intimidation. This report presents the Model Policy, which is organized into the following eight points: (1) Prohibition…

  18. Bulimia: Issues a University Counseling Center Needs To Address.

    Whitner, Phillip A.; Shetterly, Arminta

    The eating disorder known as bulimia is a relatively new and baffling phenomenon. This paper raises questions that college and university counseling center professionals need to address regarding this phenomenon. The first section focuses on defining the term "bulimia" and its evolution. The second section identifies numerous symptoms that need to…

  19. The non addressed mail; Le courrier non adresse

    NONE

    2001-07-01

    In 1999, the non addressed mail aggregated i million tons. Today there is no selective collection of these wastes. The ADEME (french agency for the environment and the energy mastership) drove a study to propose and evaluate the cost of a selective collection. This document presents the results of the study. (A.L.B.)

  20. A Breath of Fresh Air: Addressing Indoor Air Quality

    Palliser, Janna

    2011-01-01

    Indoor air pollution refers to "chemical, biological, and physical contamination of indoor air," which may result in adverse health effects (OECD 2003). The causes, sources, and types of indoor air pollutants will be addressed in this article, as well as health effects and how to reduce exposure. Learning more about potential pollutants in home…

  1. How Teacher Educators Can Address Our Nation's Financial Crisis

    Dowdell, John; McElfresh, Dwight; Sikula, John

    2009-01-01

    This article from Ashland University reports on what one university, well known for its Teacher Education programs, is doing in an economically depressed state to address our country's financial crisis. Ohio has mandated that financial literacy be taught in high schools by 2010. Reported herein is what is being done to prepare teachers for this…

  2. Some diagnostic and therapeutic controversies in glaucoma addressed

    Müskens, Rogier Peter Hendrik Maria

    2008-01-01

    In the five studies contained in this thesis, several controversies on the diagnosis of and therapy for glaucoma have been addressed. The first part of this thesis consisted of three studies that aimed tot improve existing technologies for diagnosing glaucoma. The latter part consisted of two

  3. Addressing Physical and Emotional Issues in Children's Literature

    Johnson, Jonathon

    2010-01-01

    The purpose of this paper is to examine how physical and mental disabilities are addressed in children's literature. Many authors are able to integrate the issues into their work in a way that enhances the story and benefits the reader. As young readers learn about the issues and struggles faced by children with mental and physical disabilities,…

  4. State Legislation to Address Childhood Obesity. Program Results Brief

    Fiester, Leila

    2012-01-01

    An estimated 12.5 million American children and teens are obese. Over time, the diseases and disabilities associated with obesity may undermine this population's health and result in substantial social and economic costs. Policies that address children's nutrition and physical activity are an important tool in reversing the obesity epidemic. More…

  5. 32 CFR Appendix B to Part 286 - Addressing FOIA Requests

    2010-07-01

    ... Ballistic Missile Defense Organization Defense Systems Management College National Defense University Armed... 32 National Defense 2 2010-07-01 2010-07-01 false Addressing FOIA Requests B Appendix B to Part 286 National Defense Department of Defense (Continued) OFFICE OF THE SECRETARY OF DEFENSE (CONTINUED...

  6. Second-Person Address Forms in Contemporary Uruguayan Children's Literature

    Rosales Lagos, María José; Moyna, María Irene

    2016-01-01

    In this study, we analyze the representations of singular address ("voseo," "tuteo," and "ustedeo") in contemporary Uruguayan children's literature from 1997 to 2011 as part of a broader analysis of variation and change in Uruguayan Spanish (Behares 1981; Bertolotti 2011; Bertolotti and Coll 2003; Elizaincín and Díaz…

  7. Challenging structures through addressing gender-based violence

    Getting the past right in West Africa and beyond: Addressing gender-based ... 2 See Convention on the Elimination of All Forms of Discrimination against Women .... 6 The Protocol to the African Charter on Human and People's Rights on the ...

  8. Ronald Reagan's "Star Wars" Address: Mythic Containment of Technical Reasoning.

    Rushing, Janice Hocker

    1986-01-01

    Views Reagan's "Star Wars" address as part of the culturally evolving myth of the New Frontier. Discusses how the speech creates the illusion of both preserving and transcending science by (1) subordinating technical reasoning to prevent nuclear holocaust and (2) using technoscience to rescript history and remove temporal and spacial…

  9. 10 Translanguaging as an approach to address language inequality ...

    To address this social injustice issue, academic literacy practitioners have a critical ... media of communication, instruction and assessment in education. .... Childs (2016, citing Garcia 2014: 3) argues this point by noting that translanguaging is ..... their cognitive skills because the activities that required them to move across ...

  10. Assessing Competency to Address Ethical Issues in Medicine.

    Cohen, Robert; And Others

    1991-01-01

    A study evaluated the feasibility of an objective structured clinical examination to assess the competence of foreign medical school graduates, clinical clerks, and interns to address clinical ethical situations. The University of Toronto's experience with the measure found it useful but in need of improvement. (MSE)

  11. New Simulation Models for Addressing Like X–Aircraft Responses ...

    New Simulation Models for Addressing Like X–Aircraft Responses. AS Mohammed, SO Abdulkareem. Abstract. The original Monte Carlo model was previously modified for use in simulating data that conform to certain resource flow constraints. Recent encounters in communication and controls render these data absolute ...

  12. Addressing domestic violence in primary care: what the physician ...

    Domestic violence (DV) is quite prevalent and negatively impacts the health and mental wellbeing of those affected. Victims of DV are frequent users of health service, yet they are infrequently recognized. Physicians tend to treat the presenting complaints without addressing the root cause of the problem. Lack of knowledge ...

  13. Teaching Digital Natives: Promoting Information Literacy and Addressing Instructional Challenges

    Neumann, Crystal

    2016-01-01

    Technology must be used as a teaching and learning tool to help students succeed. However, educators must be proactive in identifying some of the pitfalls of technology, such as information illiteracy. The phenomenological study covers how English instructors from Indianapolis, who teach first year students, address information literacy and the…

  14. Imaginative Thinking: Addressing Social Justice Issues through MovieMaker

    Boske, Christa A.

    2009-01-01

    Purpose: The purpose of this paper is to examine the experiences of aspiring school leaders who utilized artmaking in this case, photography, poetry, music, collage, and short films through Microsoft MovieMaker as a means for addressing injustices within surrounding school communities. The paper aims to explore how aspiring school leaders…

  15. "Back-Stage" Dissent: Student Twitter Use Addressing Instructor Ideology

    Linvill, Darren L.; Boatwright, Brandon C.; Grant, Will J.

    2018-01-01

    In this content analysis, we explored how students address instructor ideology in the university classroom through the social media platform Twitter. We employed Boolean search operators through Salesforce Marketing Cloud Radian6 software to gather tweets and identified English language tweets by how students referenced their instructor's…

  16. Addressing Maslow’s deficiency needs in smart homes

    Brink, M.; Bronswijk, van J.E.M.H.

    2013-01-01

    Modern smart homes contain elements from different technical disciplines, such as home automation, robotics, and tele-heath. We investigated to which extent smart-home systems address the different levels of deficiency needs of Maslow, and the corresponding level of integration of smart-home

  17. Utilizing Motivational Interviewing to Address Resistant Behaviors in Clinical Supervision

    Wahesh, Edward

    2016-01-01

    Motivational interviewing is presented as an approach to address resistant behaviors in clinical supervision. A case example is used to illustrate the process in which the relational and technical elements of motivational interviewing can be applied to supervisee resistance. Implications for supervisors and researchers are discussed.

  18. Can Innovation Save Gifted Education? 2010 NAGC Presidential Address

    Robinson, Ann

    2012-01-01

    Connecting innovation with gifted education is a necessity not only in the current political climate but also because it is a field with deeply held beliefs about the importance of problem solving, creativity, imagination, and invention--all critical components of innovation. In this address, the author focuses on three key ideas. First, she…

  19. Addressing the Need for Management Processes for Higher Education Accreditation.

    Brennan, Linda L.; Austin, Walter W.

    2003-01-01

    The accreditation standards of the Association to Advance Collegiate Schools of Business (AACSB International) ask business schools to describe consistent processes that provide for operational consistency and continuous improvement in support of the schools' stated missions. This article addresses the identification of requisite quality…

  20. Cultural and Social Interpretation of Chinese Addressing Strategies

    Yin, Yahui

    2010-01-01

    This paper examines the influence of Chinese cultural factors on the addressing terms, together with the history of their use, the social dynamics involved in their use. Through the examination of exact terms, the author demonstrates to the reader, the deeply rooted cultural factors behind it and different ways that these terms can be used,…