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M.T. gratefully acknowledges financial support from Lubrizol Limited and, together with J.E., thank the Engineering and Physical Sciences Research Council (EPSRC) grant EP/L015307/1 for the Molecular Analytical Science Centre for Doctoral Training (MAS-CDT). C.G acknowledges the Euler cluster managed by the HPC team at ETH Zurich for computational resources and is grateful for computational support from the UK national high performance computing service, ARCHER, for which access was obtained via the UKCP consortium and funded by EPSRC grant EP/P022561/1. Benzotriazole (BTAH) has been used for several industrial applications, but most commonly as a corrosion inhibitor for copper, since the 1950s. However, the mechanism of its interaction with copper surfaces at the atomistic scale is still a matter of debate. Here, the adsorption of BTAH onto a clean Cu(110) surface has been investigated by a combination of scanning tunnelling microscopy, X-ray photoelectron spectroscopy, high resolution electron energy loss spectroscopy and density functional theory calculations. Different supramolecular structures have been observed depending on molecular coverage and annealing. In the low coverage regime, flat lying deprotonated species are formed which give way to benzotriazolate molecules in an upright configuration by increasing the BTAH exposure. The ensuing monolayer is self-limiting but, upon annealing above 150 °C, transforms into a highly ordered nano-ridge structure resulting from a significant in-plane and out-of-plane reconstruction of the surface. All structures are characterised by a strong molecule-substrate interaction and the high coverage phases are dominated by the formation of metal-organic complexes between copper adatoms and benzotriazolate species. These findings shed light on the nature and strength of the interaction occurring between BTAH and copper which lies at the basis of the effectiveness of this prototypical corrosion inhibitor. Postprint

The NBS bromination of 1,4-dimethoxy-2,3-dimethylbenzene has been examined under a variety of conditions in both 1,1,1-trichloroethane and benzotrifluoride. Four different bromination products have been isolated including the previously unknown 1-bromo-4-bromomethyl-2,5-dimethoxy-3-methylbenzene whose single crystal X-ray structure is presented. The synthetically useful 2,3-bis(bromomethyl)-1,4-dimethoxybenzene is readily prepared using either solvent and it has been converted into new sulfur-containing quinone derivatives Postprint

Intense ultra-short XUV-pulses from the Free Electron Laser in Hamburg (FLASH) were used in combination with the synchronized near-infrared (NIR) radiation from a femtosecond laser to perform two-color experiments on rare gas atoms and small molecules. Results of atomic photoionization in the presence of a NIR dressing field are presented and discussed for the low field regime, i.e. for intensities of less than 10 11 W/cm 2 . In particular, the analysis of two-color Above Threshold Ionization (ATI) as a function of the relative orientation of the polarization vectors of both photon beams provided detailed information about the partial photoionization crosssections by comparing the experimental results with theoretical values obtained by employing second-order perturbation theory and the “soft-photon” approximation. Furthermore, a first time-resolved study was performed on the photodissociation of molecular hydrogen. In this proof-of-principle experiment, the excited atomic fragments, produced in the primary interaction with the intense XUV pulse, are probed by a time delayed NIR laser pulse that ionizes these fragments.

Resumen Objetivo Revisar sistematicamente en la literatura cientifica las evidencias que evaluan la seguridad de la vacuna por via oral contra rotavirus. Material y metodos Buscamos estrategicamente en la base de datos Medline, Trip Database y SUM Search, sin restriccion en el lenguaje, cualquier ensayo clinico que evaluara la seguridad de las vacunas de rotavirus por via oral disponibles a la fecha en lactantes (RotaTeq® o Rotarix®). El diseno de estudio de los articulos incluidos correspondio a investigaciones aleatorizadas, cegadas y controladas con placebo, publicadas desde el ano 2005 hasta septiembre de 2009. Resultados De 204 titulos encontrados, 16 articulos completos reunieron criterios basicos y se incluyeron 11 de estos. Un total de 88.017 pacientes se inmunizaron con alguna de las dos vacunas contra rotavirus disponibles frente a 75.538 con placebo. Los eventos adversos mas frecuentes fueron: fiebre (16,02%), diarrea (7,8%) y vomitos (5,2%); estadisticamente, no existio diferencia al compararlas con placebo. Conclusion Los efectos adversos graves relacionados con las vacunas orales de rotavirus se presentan en cifras bajas.

A vertically and horizontally well-integrated quality improvement team is essential for effective quality data collection and implementation of improvement measures. We outline the quality structure of a large academic pathology department and describe successful projects across multiple divisions made possible by this tightly integrated structure. The physician vice chair for quality organizes departmental quality efforts and provides representation at the hospital level. The department has an independent continuous quality improvement unit and each laboratory of the department has a staff quality improvement representative. Faculty and staff experts have interacted to produce improvements such as accurate container labeling, efficient triage of specimens, and reduction of unnecessary testing. Specialized task forces such as the Courier Task Force are producing concrete recommendations for process improvement. All phases of pathology patient care are represented by faculty and staff who are trained in quality improvement, and each position touches and communicates actively with levels above and below itself. The key to the department’s approach has been the daily attention to quality efforts in all of its activities and the close association of faculty and staff to accomplish the goals of greater efficiency, safety, and cost savings.

The transcription factor NusG from Escherichia coli modulates the rate of transcript elongation by RNA polymerase and the efficiency of Rho-dependent transcript termination. It consists of two globular domains with an extra loop extending out of the amino-terminal domain in the position that is occupied by a third globular domain in some NusG homologues. We have tested the role of this appended mini-domain by assaying the elongation and termination enhancement activities of variants. The results show that variants with changes in their sequence do not cause a loss of functions, whereas variants with the deletions of the residues in that domain are much less active for both functions. This finding suggests that the mini-domain serves as a structural element for an interaction rather than as a site for residue-specific contacts.

We compare step morphologies on surfaces of Al-rich metallic alloys, both quasicrystalline and crystalline. We present evidence that the large-scale step structure observed on Al-rich quasicrystals after quenching to room temperature reflects equilibrium structure at an elevated temperature. These steps are relatively rough, i.e., have high diffusivity, compared to those on crystalline surfaces. For the fivefold quasicrystal surface, step diffusivity increases as step height decreases, but this trend is not obeyed in a broader comparison between quasicrystals and crystals. On a shorter scale, the steps on Al-rich alloys tend to exhibit local facets (short linear segments), with different facet lengths, a feature which could develop during quenching to room temperature. Facets are shortest and most difficult to identify for the fivefold quasicrystal surface.

The self-assembly of monolayers of benzyl mercaptan (benzenemethanethiol, C 6 H 5 CH 2 SH) on Au(1 1 1) at room temperature has been studied by low energy electron diffraction and high resolution electron energy loss spectroscopy (EELS). It was found that the orientation of the molecule depends on coverage with the aromatic ring being parallel to the surface for low coverage and more perpendicular at higher coverage. Low energy electron diffraction indicates a (√7×√7) R 19.1° adsorbate structure at saturation coverage.

The room temperature deposition of PTCDA on hydrogen passivated Si(1 1 1), as a function of evaporation temperature and dosing time, has been studied by STM. At low evaporation temperature, 200 °C, clusters with an average size of 3.5 nm are formed on the surface. The mobility of the small clusters is so high, even at room temperature, that most of the clusters are trapped at surface defects. By increasing the evaporation temperature to 230 °C, larger clusters are formed which have lower mobility. The growth process is identified as a Volmer-Weber mechanism. On increasing the evaporation temperature further to 250 °C, crystals with dendritic shape are formed with an average size of 150 nm. The terraces of the crystal are formed with the (1 0 2) basal plane of the α-phase. Molecular resolution on the terrace also allows us to identify the molecular mechanism involved in the growth of the dendritic crystals.

The presence of adsorbates can modify the morphology of the underlying substrate. The modifications are the results of a subtle thermodynamic balance between intermolecular and molecular-substrate interactions together with the surface relaxation energy. The information on how the substrate structures are influenced by the adsorbates, and therefore, the physical and chemical properties of the resulting interface is fundamentally important. In this review, we examine facetting of transition metals induced by either atomic species or organic molecules. First we focus on facetting induced by atomic species and small molecules under high pressure or UHV conditions. Following that, organic molecules containing several electronegative elements, such as amino acids, benzoic acid and aminobenzoic acid, are examined. These organic molecules can induce large scale facets with great similarity on fcc crystal surfaces. Learning from the correlation between the facetting induced by these molecules and those of atomic species, we try to rationalise the molecular mechanism for the formation of adsorbate induced facets.

We show that, counterintuitively, maleic anhydride on Si(1 0 0) surfaces adsorbs on inter-row sites. Our first principles simulations establish that this site is preferred for coverages of less than 1/8 ML. In simulations of scanning tunnelling images we establish also, that the corrugation is enhanced by more than 0.5 A, if a single molecular state contributes to the tunnelling current. The combined evidence of images and simulations allows the conclusion that experiments in fact reveal the geometry of single molecular wavefunctions.

The chemisorption of glycine and its fully deuterated analogue, d5-glycine, deposited on the clean and Na modified Sið 100 Þ-2 � 1 surfaces, has been studied by high-resolution electron energy loss spectroscopy (HREELS) and ab initio methods. HREELS indicates that chemisorption of glycine and d5-glycine on Na/Sið 100 Þ-2 � 1 occurs through cleavage of the OH and OD bonds in the carboxylic groups. The adsorbed species are bonded through the formation of an ionic bond between the deprotonated carboxylate group and the adsorbed Na atom, leading to species in a bidentate coordination. In contrast, we observe monodentate glycinate and d5-glycinate species following the exposure of Sið 100 Þ-2 � 1 to glycine and deuterated glycine. The thermal stability of glycine on clean Sið 100 Þ-2 � 1 and on the Na modified surface has been studied by heating the substrate to various temperatures. 2002 Elsevier Science B.V. All rights reserved.

The adsorption induced surface chirality has been examined with high resolution STM observation of ordered glycine on Cu{1 1 0} surface. Two domains with different internal molecular arrangement have been identified. The homochiral domain shows a pseudo-centered structure while the heterochiral domain presents a clear glide plane symmetry. The lateral relationship between these two domains has also been analysed, which gives the details of the assignment of individual features in the STM images.

High resolution electron energy loss spectroscopy has been used to study the adsorption of water on the clean and Na modified SrTiO 3 (1 0 0)-1×1 surfaces. The vibrational spectrum of clean SrTiO 3 shows three dipole active bands, characteristic of perovskite materials, at 170, 460 and 730 cm −1 . In good agreement with previously published experimental results, we show that water does not adsorb on the clean defect free SrTiO 3 (1 0 0)-1×1 surface. On the other hand, the vibrational spectra of the Na modified SrTiO 3 (1 0 0)-1×1 surface exposed to water shows clearly an OH stretching vibration which indicates the presence of hydroxyl species at the surface. The continuous observation of the 1×1 pattern in low energy electron diffraction indicates that the surface reconstruction is preserved even after exposure of the surface to water.

The defect transformation under growth of submonolayer oxides on silicon surfaces is studied in situ on reconstructed Si(100)-2×1 and Si(111)-7×7 surfaces and on hydrogenated Si surfaces of Si nanocrystallites. The methods of the quenching of the photoluminescence of bulk c-Si due to surface recombination and of the infrared free carriers absorption in mesoporous Si are used. It is shown that dangling bonds at Si–Si dimers are not recombination active. Non-radiative surface defects are generated during the earliest stages of oxidation. The generation of hole traps is tightly related to an increase of physisorbed H 2 O at hydrogenated Si surfaces during the native oxidation.

The adsorption of R-phenylglycine on Cu(1 1 0) surfaces shows that the periodic superstructure of the chiral overlayer destroys the substrate mirror plane symmetry. Here, we report on the novel linear dichroism electron scattering method to determine the chirality, based on the unique symmetry of the chiral surface. The details of the molecular structure, with the absolute surface chirality, are derived from the azimuthal variation of intensity of individual vibrational modes.

The adsorption of 4-aminobenzoic acid on the clean and Na modified Si(1 0 0)-2×1 surfaces has been studied by high-resolution electron energy loss spectroscopy (HREELS) and near edge X-ray absorption fine structure. HREELS indicates that adsorption of 4-aminobenzoic acid on Na/Si(1 0 0)-2×1 occurs through cleavage of the OH bond in the carboxylic group. The 4-aminobenzoate species are bonded through the formation of a delocalized bond between the deprotonated carboxylate group and the adsorbed Na atom, leading to species in a bidentate coordination. At room temperature, 4-aminobenzoate saturation is reached at a coverage of one 4-aminobenzoate species per Na or Si dimer. At this coverage, the molecules are tilted in the polar direction by 61±5° to the surface plane. In contrast, we observe monodentate 4-aminobenzoate species following the exposure of Si(1 0 0)-2×1 to 4-aminobenzoic acid.

An exemplary independent woman for many and still a role model for some gay and lesbian couples today, Edith Guerrier contributed to the popular use of government documents in the first half of the 20th century. Part of a long-term Boston marriage with Edith Brown (1872–1932), Guerrier served at the Boston Public Library; in the U.S. Food Administration; and on the Public Documents Committee of the American Library Association. On the cutting edge of her profession in the 1920s, she led the patriotic movement to popularize government documents, created a precursor to the U.S. Government Manual; and collected some of the earliest data on actual document use. Throughout her 40-year career, she championed life and work skills, especially literacy, among young women and the public's use of documents rather than libraries archiving such material.

The adsorption of maleic anhydride on Si(1 0 0)-2×1 has been studied with high resolution electron energy loss spectroscopy and near edge X-ray absorption fine structure (NEXAFS). We observe that at low coverages the adsorption occurs mainly through cycloaddition of the CC bond to the dangling bonds of Si–Si dimers, analogous to the behaviour of cyclopentene. The Si–Si dimer bonds are not cleaved in the chemisorption, process as the continued observation of a 2×1 pattern in low energy electron diffraction shows. In the NEXAFS spectra, the absence of a π * resonance associated with the CC bond, confirms the rehybridisation of the carbon atoms in the olefin bond. The angular dependence of the resonance intensity indicates a molecular plane inclination of 48° to the substrate plane. At higher dosages, chemisorbed maleic anhydride species are bonded to the Si surface atoms via a single Si–C linkage with retention of the CC double bond. In this case, the dissociated hydrogen bonds to one of the neighbouring Si atoms.

The passivation of Si(1 0 0), Si(1 1 3) and Si(1 1 5) with ethanol, isopropanol and tert -butanol has been studied with high resolution electron energy loss spectroscopy (HREELS) and low electron energy diffraction (LEED). The HREEL spectra show clearly that the alcohols chemisorb dissociatively with the formation of a Si–O–C linkage on the three surfaces. We observe a considerable chemisorption of water on the ethoxy and tert -butoxy passivated Si(1 0 0)-2×1 surfaces. From the disappearance of the 2×1 LEED pattern, it can be concluded that the chemisorption of water occurs through a cleavage of the Si–Si dimer bond. In contrast, isopropoxy species on Si(1 0 0)-2×1 reduces dramatically the reactivity towards water. However, Si(1 1 3) and Si(1 1 5) turn out to be much more reactive towards water molecules after the adsorption of any of the alcohols.

The formation of electronic states in the fundamental gap at the maleic anhydride/Si(1 0 0)-2×1 interface has been studied with photoluminescence (PL) measurements and high resolution electron energy loss spectroscopy (HREELS). We observe that the room temperature adsorption of maleic anhydride on Si(1 0 0)-2×1, where the organic molecules are mainly in a di-σ coordination, results in a gap state density D it =1.8(2)×10 12 eV −1 cm −2 which is slightly lower than determined for the clean Si(1 0 0)-2×1 surface. After heating maleic anhydride/Si(1 0 0)-2×1 to 1115 K, the gap state density has increased to 6.4(6)×10 12 eV −1 cm −2 which we relate to the formation of silicon carbide structures on the silicon surface.

The structure of benzoate on Na/Si(100)-2×1 has been studied by high resolution electron energy loss spectroscopy, X-ray photoelectron spectroscopy and near edge X-ray adsorption fine structure spectroscopy. At room temperature, benzoic acid (C6H5COOH) chemisorbs on Na/Si(100)-2×1 through a cleavage of the OH bond in the carboxylic group. The benzoate molecules formed are bonded exclusively to the sodium atoms in a bidentate coordination, in which the oxygen atoms are equivalent. At room temperature, benzoate saturation on Na/Si(100)-2×1 is reached at a coverage of one benzoate species for each Na atom or silicon dimer. At this coverage, the molecules are tilted in polar direction by 62°±4° to the surface plane and azimuthally rotated by 41°±4° with respect to the [01 1 ] surface azimuth. We propose an adsorbate structure, in which the benzoate molecules are oriented parallel to each other in densely packed rows.

The surface structure of ultra-thin Al 2 O 3 films on NiAl(110) and Ru(0001) was investigated by using high-resolution electron energy loss spectroscopy (HREELS). On a semi-empirical basis, the three phonon loss features, ν 1 (380∼430 cm −1 ), ν 2 (620∼660 cm −1 ), and ν 3 (850∼900 cm −1 ), of crystalline Al 2 O 3 films were assigned to collective excitations of the microscopic vertical stretching motion of in-phase O–Al layers and to the stretching motions of the tetrahedrally and octahedrally coordinated Al–O species, respectively. To a good approximation, the distinct observation of the ν 1 mode in the HREEL spectra of Al 2 O 3 films can be a sign for the synthesis of a vertically well-defined Al 2 O 3 phase. The relative intensity between the ν 2 and the ν 3 loss features has been used to determine the most probable oxide structure, amorphous, transition, or α-like, by using the relative site occupation ratio of Al 3+ cations to hexagonal closely packed O 2− anions.

Exposure of Cu(110) at 90 K to a sub-monolayer amount of benzoic acid gives rise to both benzoate and undissociated acid species. Low coverage STM shows the diffusion and re-arrangement of molecules on the edge of clusters, while higher coverage images show one-dimensional dimeric features, assigned to benzoic acid dimers, growing anisotropically in the 〈001〉 direction. At higher temperature, a different dimer chain along the (±4, 3) directions can be observed. From temperature-dependent FTIR, the deprotonation of the flat-lying species takes place between 120 and 170 K. Further annealing shows crystallization at 183 K, which results in the periodic α-phase. In contrast, for the multilayer surface, the desorption of multilayer starts at 200 K and results in all molecules being upright in the c(8×2) structure.

The hybrid inorganic–organic molecule γ-glycidoxypropyltrimethoxysilane is used as an adhesion promoter because of its ability to act as a molecular bridge between chemically different phases. In this paper we concentrate on the interaction of the organofunctional glycidoxy end chain of this molecule on a γ-Al2O3(111) mimic created by oxidation of NiAl(110). In order to understand better the interaction of this functionality, the glycidoxy moiety was modelled using glycidyl isopropyl ether and epoxyhexane. Reflection–absorption infrared spectroscopy studies of these model compounds demonstrate that monolayer adsorption on the γ-Al2O3 film is non-dissociative, with both molecules being only weakly perturbed, supporting the idea that the organofunctional end group in hybrid inorganic–organic adhesion promoters remains intact, available to react potentially with the adhesive on application.

Azimuthal orientations of 9-anthracene carboxylate (9-AC) on clean and p(2×1)O/Cu(110) surfaces were determined from a reflectance anisotropy spectroscopy (RAS) signal derived from an intramolecular electronic transition. The magnitude of the molecular signal on the p(2×1)O/Cu(110) surface is 4–5 times larger than on the clean surface. We present a complete vibrational assignment of adsorbed 9-AC based on Fourier transform infrared and on- and off-specular high resolution electron energy loss spectroscopy (HREELS) and ab initio calculations. Correlation of the off-specular HREELS on p(2×1)O/Cu(110) with the RAS results demonstrates that the magnitude of the RAS signal depends on the degree of azimuthal orientation.

The adsorption of benzoic acid on Na–Si(100)-2×1 ( Θ Na =0.5) at room temperature leads to benzoate in a bidentate coordination. High-resolution electron energy loss spectroscopy spectra show an intense ν s (OCO) stretching vibration, which is characteristic for benzoate aligned perpendicular to the substrate surface. In contrast, we observe monodentate benzoate species following the exposure of Si(100)-2×1 to benzoic acid at room temperature. On both surfaces, the dissociated hydrogen atom bonds to one of the silicon surface atoms. Removal of benzoate from Na–Si(100)-2×1 is observed after heating the silicon substrate to 300°C for 1 min.

In this high resolution electron energy loss spectroscopy study, we demonstrate the growth of an ultrathin polyimide film on Si(100)-2×1 exhibiting Si–C bonds at the organic film/substrate interface. For the controlled formation of the film, which has been carried out by molecular deposition, maleic anhydride, 1,4-phenylene diamine and pyromellitic dianhydride have been sequentially deposited on Si(100)-2×1 at room temperature. Imidisation was initiated by thermally curing the amic acid film at 430°C. The vibrational data confirm the absence of oxidised silicon at the film/substrate interface.

Upon submonolayer deposition of Azure A molecules onto reconstructed Au(1 1 1), two-dimensional quasi-rectangular islands are observed by low-temperature scanning tunneling microscopy. Strikingly, the 22 x root 3 reconstruction with alternating hexagonal close packed (hcp) and face centered cubic (fcc) domains of the native Au(1 1 1) surface layer is found to be strongly modified underneath the self-assembled islands of Azure A molecules. The bridge-hcp-bridge-fcc-bridge period of 63 angstrom on clean Au(1 1 1) is expanded by about 12% and occasionally reaches even 22%. This increase of the unreconstructed fcc areas underneath the molecular islands reflects a partial lifting of the reconstruction caused by the interaction between the adsorbed molecules and the outermost Au atoms at the molecule-metal interface. (C) 2008 Elsevier B.V. All rights reserved.

We show for the first time that, with two coadsorbed periodic structures it is possible to observe in a diffraction condition unique to one structure a relative enhancement of the vibrational losses characteristic of the species contained in the respective periodic structure. A recently developed SPA-LEED instrument equipped with an electron monochromator and analyser was used to distinguish true elastic diffraction from inelastic diffraction in the vibrational losses of coadsorbed (2×3)N/Cu(110) and the α-phase benzoate 4 3 −1 5 structure on Cu(110). Vibrational enhancements by factors of 4–20 were found in energy loss spectra and momentum-resolved spot profiles. Inelastic spot profiles are qualitatively consistent with a kinematic description of the energy–momentum conservation induced broadening from both loss-before-diffraction (L-D) and diffraction-before-loss (D-L) events.

Using reflection absorption infrared spectroscopy (RAIRS), the coverage-dependent reorientation of the benzoate species on the (110) and (111) faces of copper is compared and contrasted. Whereas on Cu(110) benzoate reorients from a flat-lying to an upright orientation with increasing coverage, on Cu(111), at all coverages, benzoate is aligned normal to the surface. The formation of periodic, flat-lying copper–benzoate structures has been attributed to the availability of metal adatoms, which differs dramatically between the (111) and (110) faces. We discuss the face specificity of molecular orientation by comparing calculated formation energies of adatom vacancies from ledges and kink sites on (100), (110) and (111) faces. Further support for this model is given by the evaporation of sodium, either by pre- or post-dosing, onto low-coverage benzoate/Cu(111), which induces benzoate to convert from a perpendicular to a parallel orientation. Likewise, coevaporation of Cu while dosing benzoic acid onto the Cu(111) surface also results in a majority of flat-lying benzoate species. Finally, for adsorption on the p(2×1)O/Cu(110) reconstruction, benzoate occurs only as the upright species, which is consistent with reducing the copper mobility and availability on the (110) face. We therefore suggest the possible role of metal adatoms as a new mechanism in controlling adsorbate orientation and therefore face specificity in surface reactions.

The transcription factors NusA and NusG from Escherichia coli are modulators of the RNA polymerase elongation reaction and Rho-dependent transcription termination. NusA decreases the elongation rate and termination efficiency while NusG increases both activities. Both Nus factors are able to physically interact with Rho and with RNA polymerase. Experiments with purified components designed to determine whether these factors act independently or competitively showed that the change in elongation rate was a composite of their individual effects, that the combined effect on termination was dependent on the reaction conditions and that the two factors do not compete for their sites of action for either effect. The two factors were also found not to enhance significantly the slight (20%) inhibition of elongation caused by 200 microM guanosine 3',5'-bisdiphosphate (ppGpp) during transcription in vitro. The results also show that the effects of NusA and NusG on RNA polymerase elongation and Rho function are contrary to the inverse relationship between elongation and termination that is expected for a kinetic coupling of Rho action to RNA polymerase elongation. This property suggests that in addition to their known actions on RNA polymerase that influence the length of pausing, these factors act on some other rate-limiting step of the Rho-dependent termination process.

The chemisorption of glycine (NH 2 CH 2 COOH) and its fully deuterated analogue d 5 -glycine, vacuum deposited on a clean Cu{110} surface, have been investigated using reflection absorption infrared spectroscopy (RAIRS). At room temperature (300 K) a saturated monolayer is dissociatively adsorbed producing glycine in its anionic form; a glycinate species. The orientation of the adsorbed species changes as the coverage increases with bonding occurring initially via equivalent oxygen atoms of the carboxylate group, orientated broadly perpendicular to the surface, similar to the bonding found in simple carboxylic acids. At saturation coverage, at 300 K, a different orientation of the carboxylate group is observed with the carboxylate binding in a more unidentate fashion. The IR spectra are then very similar to those of solid copper glycinate. Low energy electron diffraction (LEED) shows a poor (3×2)g pattern. On annealing this fully covered surface to 420 K, there is no significant desorption and the IR spectra show dramatic changes in relative band intensities with the spectra becoming more similar to those obtained at low coverage. The (3×2)g LEED pattern sharpens considerably. At this stage, we suggest that anionic glycine (glycinate) species are adsorbed with the O 2 –C–C–N backbone essentially parallel to the surface with interadsorbate bonding dominated by CH⋯O and N–H⋯O hydrogen bonds similar to those found in bulk glycine. The (3×2) structure is a compromise between optimal adsorbate site, intermolecular hydrogen bonding and maximum adsorbate density. With the substrate held just below room temperature, multilayers of the zwitterionic glycine form which desorb in two stages with the second layer leaving the surface at a higher temperature than the other layers. At liquid nitrogen temperatures (85 K), some of the glycine is present on the surface in its acid form, as evidenced by the presence of a carbonyl (CO) stretch.

The adsorption of benzoic acid on Cu(110) between 300 and 350K results in benzoate species oriented perpendicular to the surface with a c(8 × 2) periodicity at saturation coverage. STM images of the ordered structure and non-dipolar scattering in HREELS demonstrate alignment in the [110] azimuth. We interpret the tunnelling mechanism in STM, negative ion resonance scattering in HREELS, and assign low-frequency vibrational modes utilising ab initio molecular orbital calculations. We propose a model with four molecules per c(8 × 2) unit cell (ϑ = 0.25ML) arranged in two out-of-phase, zig-zag rows along the [001] direction with the car☐ylates bound in short bridge sites alternately three and five lattice constants apart along the [110] direction. Adsorbate-induced dipole-active phonons in the frequency range 65–185 cm −1 in HREELS support the adsorption model.

We have extended the displaced harmonic oscillator model for negative ion resonance (NIR) scattering in high-resolution electron energy loss spectroscopy (HREELS), to interpret the energy transfer processes leading to disordering in STM and LEED, by allowing the curvature of the negative ion PES to be different to that of the ground PES. For the benzoate-Cu(110) system, the results of the extended model are significantly better if the ground and negative ion PESs have frequencies hω = 0.40 and 0.48 eV, respectively, rather than the same frequency. The large resonance width and asymmetry, but not the small overtone to fundamental excitation probability ratio, observed in HREELS can be accounted for with values of the coupling constant, β = 22.2 and inverse lifetime of Г = 0.6 eV (1.1 fs). These parameters, with nD = 7 are simultaneously able to account for the ratio of the STM:LEED disordering cross-sections and, most significantly, predict the large slope observed in the STM disordering cross-section as a function of bias. The properties of the probability distribution, Pn(ϵi, for the NIR process, involving two Franck-Condon transitions, is contrasted with the DIET process and some non-classical behaviour for the case ω0 ≉ ω1 is noted.

We report the first I–V measurements of a negative ion mediated , molecular manipulation process, propose a model involving field-induced shifting of the resonance which predicts a disordering rate symmetric about zero sample bias, and then extend the displaced harmonic oscillator model to account for the larg slope in the I–V curve found for c(8 × 2) benzoate/Cu(110).

The beta-chemokines monocyte chemotactic protein 1 (MCP-1), macrophage inflammatory protein 1 alpha (MIP-1alpha), MIP-1beta and regulated on activation, normal T cells, expressed and secreted (RANTES) induced the in vitro migration of the monocytic cell line MonoMac-6. MCP-1 exhibits the most potent chemotactic effect on this cell line while MIP-1alpha, RANTES and to a lesser extent MIP-1beta were more moderate inducers of cell migration. MonoMac-6 migration in response to chemokines was shown to be a chemotactic and not a chemokinetic response, which was inhibited by pertussis and cholera toxins suggesting a role for G proteins in chemokine receptor-mediated signalling in these cells; chemotaxis of MonoMac-6 cells in response to MCP-1 was abrogated by the addition of anti-MCP-1 antibody. The response of MonoMac-6 cells to the alpha-chemokines IL-8, IP-10, growth-related peptide (Gro) alpha and MIP-2beta was substantially weaker than to the beta-chemokines. MCP-1 caused an alteration in cellular morphology by increasing ruffling at the cell membrane and the number of cells exhibiting extended pseudopodia. The chemotactic response of MonoMac-6 cells to beta-chemokines was compared with less well-differentiated myelomonocytic cell lines. THP-1 showed a similar, but weaker response to the beta-chemokines while both HL60 and U937 failed to respond to any member of this subfamily when tested under the same conditions. These results suggest that the differentiation status of cells of monocytic lineage may affect their response to beta-chemokines.

The adsorption of ethanol, isopropanol and tert-butanol on clean and H2O pre-dosed Si(100)-2 × 1 has been studied by high resolution electron energy loss spectroscopy (HREELS). We observe that the reactivity of the alcohols towards Si(100)-2 × 1 presaturated with H2O decreases with increasing number of methyl groups in the series (CH3)nCH3 − nOH (n = 1, 2, 3). All alcohols chemisorb on the silicon substrates via a deprotonation of the OH group with the formation of alkoxy and silicon hydride species. In the case of H2O saturated Si(100)-2 × 1, the adsorption involves cleavage of the SiSi bond of the silicon surface dimer.

The chemisorption of benzoic acid (C6H5COOH) and aniline (C6H5NH2) on Si(100)-2 × 1 at room temperature has been studied with high resolution electron energy loss spectroscopy (HREELS) and low electron energy diffraction (LEED). The vibrational data indicate that both aromatic species adsorb dissociatively on Si(100)-2 × 1 via a deprotonation reaction of the functional group. A SiOC or SiNC linkage, respectively, is formed between the silicon substrate, still reconstructed, and the intact phenyl ring. In both cases, the hydrogen atom bonds to a neighbouring silicon atom.

We examine the consequences of multiple scattering in HREELS and propose a new approach to defining the background for the purpose of resolution enhancement when the contribution of broad, continuum excitations interferes with discrete features of interest, e.g. adsorbate features. The method, which should be generally applicable to metals, oxides and semiconductors, is based on the Fourier-log deconvolution procedure for removing the Poisson distribution of multiple losses. The effects of noise and variation in instrumental sensitivity and transmission functions are considered. Statistical testing of the performance of currently available Bayesian resolution enhancement codes has been evaluated with synthetic spectra.

The chemistry of nitro- and amine-substituted aromatic molecules on a Cu(110) surface has been studied using Fourier transform infrared spectroscopy, by comparison of the adsorption of nitrobenzene (NB), p-dinitrobenzene (pDNB) and p-nitroaniline (pNA). When nitrobenzene was adsorbed on a clean Cu(110) surface at room temperature, it decomposed to form a phenyl species with the C2 axis nearer the surface normal than parallel. At 83 K, multilayer nitrobenzene formed with a vibrational spectrum, in good agreement with gas-phase data; upon warming, a phenyl species remained, which was stable to about 350 K. AES of the species present following dosing at 300 K showed carbon and oxygen but no nitrogen. When p-dinitrobenzene was adsorbed it decomposed, losing one NO2, to form a stable nitrophenyl species on Cu(110) orientated with the C2 axis closer to the surface normal than the phenyl species derived from nitrobenzene. In contrast, p-nitroaniline does not decompose on the Cu(110) surface at room temperature. Multilayer and monolayer p-nitroaniline are distinguished by frequency shifts of NO2 and NH2 modes, attributed to intermolecular hydrogen bonding. In the monolayer, the amine group appears to stabilise the ring-nitro group bond, allowing bonding to the surface via the NO2 group in an orientation perpendicular to the surface.

A Rho-dependent transcription terminator in Escherichia coli DNA consists of an upstream part for Rho utilization (rut) and the transcription stop point (tsp) region. To test the role of the tsp region variants of the coliphage lambda cro gene terminator, tR1, containing inserts of non-terminator sequences between its rut and tsp regions were tested for termination function. The results showed that termination occurred with high efficiency at multiple sites in each of the new sequences with the positions of the sites coinciding with transcriptional pause points in the insert sequence and that the efficiency of termination was not directly proportional to the extent of pausing at those points. Thus, in contrast to the rut sequences, which are relatively rare in DNA, many different sequence segments can function as a tsp region. Studies with isolated transcripts showed that a rut element and sequences 3' of the rut element were both needed to activate ATP hydrolysis by Rho factor with the degree of activation depending on the length and the specific sequence of the 3' segment. These results support models for Rho action in which ATP hydrolysis is coupled to interactions of Rho protein with RNA 3' of the rut region.

The chemisorption of 3-thiophene carboxylic acid on Cu(110) between 300 and 350 K has been investigated by high resolution electron energy loss spectroscopy (HREELS), scanning tunnelling microscopy (STM) and low energy electron diffraction (LEED). Ab initio molecular orbital calculations of the molecular ion aided in vibrational frequency assignments, interpretation of STM images and estimation of intra- and inter-molecular interactions influencing formation of the c(4 × 8) and p(2 × 1) structures. HREELS shows that at low coverage, the molecule lays flat with its π orbitals interacting with the surface. Increasing the coverage induces the molecules to reorient perpendicular to the surface and form a c(4 × 8) intermediate structure. Impact scattering in HREELS demonstrates that the molecules are preferentially aligned with the thiophene ring in the [110] azimuth. STM images suggest that the upright carboxylate species form rows of four adjacent molecules face-to-face along the [001] direction separated by four lattice constants in [110]. Subsequent rows are shifted by two lattice constants along [110], resulting in an overall c(4 × 8) periodicity and a coverage of 0.25 ML. With increasing coverage, the c(4 × 8) structure changes to a p(2 × 1) structure. A model with the carboxylates bound in short bridge sites two lattice constants apart along [110] with a local coverage of 0.5 ML is proposed. Steric repulsion in the p(2 × 1) structure results in rotation of the thiophene ring by an estimated 30° away from the [110] direction, consistent with impact scattering HREELS measurements. Calculated dipole-dipole repulsion between the carboxylate groups is large compared to any dipole-dipole attraction which could result from anti-parallel alignment of the static dipole moments of the thiophene rings.

In light of recent STM measurements of the O/A1(111) system, we reassign the dipole active modes observed at low coverage to resolve discrepancies between the interpretation of Strong, Firey, deWette and Erskine [Phys. Rev. B 26 (1982) 3483], invoking subsurface oxygen, and a variety of other studies which find no evidence for surface oxygen. The STM results, which show that very small island sizes are stabilized over an exposure range up to ∼ 200 L with a total coverage ≤ 0.2 ML, are incompatible with the assumption of long range periodicity required for lattice dynamical modeling. The consequence is that vibrational modes polarized parallel to the surface may become dipole active. Within an Al 3 O cluster model appropriate to exposures ≤ 3 L where most oxygen atoms are isolated species in three-fold hollow sites, the strong feature at 584 cm −1 (72 meV) is still attributed to top-layer oxygen motion perpecdicular to the surface (the symmetric Al 3 O stretch) but the second intense feature at 480 cm −1 (60 meV) is assigned to the umbrella mode involving predominantly Al motion parallel to the surface rather than the motion of two AlO layers moving perpendicular to the surface out of phase with each other. The lowest frequency mode near 224 cm −1 (28 meV) derives from the frustrated translation of the cluster perpendicular to the surface. At higher exposures (> 10 L) where multiple oxygen islands begin to appear, totally symmetric combinations of the E-derived asymmetric Al 3 O stretching motion polarised nominally parallel to the surface become dipole allowed and can be assigned to the loss at 850 cm −1 (105 meV), which was previously attributed to subsurface oxygen.

Scanning tunneling microscopy (STM) has been used to study structures formed by adsorbed formate and benzoate species on Cu(110) surfaces. Partially oxygen-precovered and clean surfaces were exposed to formic and benzoic acids, respectively. STM images show that both adsorbed formate and benzoate result in a tendency for bunched steps to align along 〈1 1 − 2〉 ; directions and to become equidistant: effectively creating small facet planes on the surface. In the case of benzoate, these planes can be described as (11 13 1) and (11 13 1 − ) planes. In the case of formate, ordered arrays of facet planes can form on step edges giving the steps a “sawtooth” appearance. Under some conditions adsorbed formate also appears to stabilize finger-like islands and pits.

Cutting stock problems typically involve the generation of feasible cutting patterns whilst minimizing waste. In some instances the sequence of cutting these patterns is important. One objective of the sequencing stage is to minimize the maximum queue of partially cut orders. This paper presents two exact methods to meet this objective and to determine the optimality of previously introduced sequencing heuristics. The first and more simple method is based on the Lower Bound. The other, a more general method, is an implicit exhaustive search procedure. Various enhancements are introduced which allow sets of up to thirty pattern types to be successfully searched. Aspects of graph theory have been utilised to minimise the size of sets of patterns to be searched. Computing experience is reported for determining optimality.

The chemisorption of 3-thiophene carboxylate (C 4 H 3 SCO 2 − ) on Cu{110} following room temperature exposure of the metal to the parent carboxylic acid has been investigated by ultra-high resolution electron energy loss spectroscopy. By taking advantage of improvements in spectrometer design and the application of maximum entropy based, data analysis techniques, it has been possible to determine almost all of the vibrational frequencies associated with this chemisorbed species. Spectra were measured at a resolution of 23 cm −1 and a further improvement by about a factor 2 was obtained by subsequent data processing. As anticapted, the molecule adopts an upright orientation at saturation coverage and modes with their dipole moment change polarised predominantly parallel to the ring-CO 2 bond are the most intense in specular scattering. Modes of CH bending character are strongly enhanced in off-specular scattering. A strong, dipole active mode at 297 cm −1 is tentatively assigned to a collective mode of the close-packed molecules based on the out-of-plane bending of the aromatic ring relative to the carboxylate plane.

Low energy ion-scattering and ion-recoil (LEIS and LEIR) spectroscopies have been used to monitor the structure and composition of an InSb(100) surface during continuous irradiation with argon ions (4.8 keV) directed at grazing incidence. Oscillations in both the scattered and recoil ion intensities have been observed during all bombardment sequences (for doses 2 × 10 16 ions cm 2 ). The periods of these oscillations show some dependence on the experimental geometry, and are close to those predicted for sputter-removal of one or two surface layers. Interestingly, the surface shows no sign of becoming amorphous even following excess ion bombardment. Details of the variations in surface composition are assigned, not only to layer-by-layer depth profiling, but also by rapid diffusion of Sb to the surface from the Sb depleted lattice. These data indicate that LEIS and LEIR can be used to monitor composition profiles with monolayer depth resolution such that different states of the same surface can be achieved simply and controllably by terminating ion bombardment following a pre-determined irradiation dose.

We have studied the effect of deuteration on the adsorption of benzoic acid on a copper (110) surface with RAIRS and HREELS. The resulting benzoate species has been characterized by the assignment of the spectra to modes of A 1 symmetry under the C 2v point group, which shows the carboxylate group and aromatic ring are perpendicular to the surface. Comparison to the non-deuterated species shows some unexpectedly large intensity changes and frequency shifts for several aromatic ring breathing modes due to coupling with modes of the carboxylate group