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OBJECTIVES The osteo-odonto-kerato-prosthesis (OOKP) procedure is a complex, multi-stage, multidisciplinary surgical intervention for the treatment of severe corneal blindness. One step of the OOKP consists of creating a precise hole into a tooth in which an optic cylinder is subsequently inserted; its shape must ensure a perfect watertight fit. The Er: YAG laser (L) used in this study is part of CARLO®, the first laser osteotome that enables surgical planning based on computed tomography data, robot guidance, and a precise execution of laser cuts in teeth and bone tissue, using laser photoablation rather than conventional mechanical methods. The purpose of this study was to assess whether the Er: YAG laser is non-inferior compared to a conventional drill. METHODS Thirty-two bovine incisors were grounded to a thickness of 1.5 mm. In 16 teeth, a 3.5 mm hole was drilled progressively into each tooth, using dental burs (B) of increasing diameter that were attached to a fixed drill machine. In the other 16 teeth, a hole was created using an Er: YAG laser at a wavelength of 2.94 µm (Part of CARLO®). In seven teeth of each group, the cylinder was inserted and fixated with polymethylmethacrylate (PMMA) bone cement. In the remaining seven teeth of each group, the cylinder was inserted without fixation material (press-fit). After bonding and drying, all specimens were stored in water until force measurements were recorded using a uniaxial traction machine. The force required to move the optical cylinder out of the hole in the tooth was measured using an Instron 3344 testing system. Scanning electron microscope (SEM) and light microscope (LM) visualization of the holes created with the laser and the drill were performed in two teeth (SEM)/four teeth (LM) per method. RESULTS Significant differences (P

International audience; Electrochemically triggered self-assembly can be effectively utilized to produce electroactive materials of tailored properties for various applications, such as sensor development. Here, we present a thin sensor film based on tannic acid (TA) and silver nanoparticles (AgNPs), ionically imprinted via electrodeposition and tailor-designed for electrochemical tracing of aluminum ions, Al(III). In the first stage, the conditions for the Al(III) printing of TA films onto an indium-tin-oxide (ITO) electrode via electrodeposition are established and optimized. To form an AgNPs-containing film, AgNPs are presynthesized via a direct reduction of Ag(I) by TA resulting in TA-stabilized AgNPs (TA@AgNPs) of 1–4 nm in size, as observed by dynamic light scattering. Next, Al(III) ions are added to complex the TA molecules adsorbed on the surface of AgNPs. The resulting Al(III)/TA@AgNPs mixture is then electrodeposited onto the ITO surface by applying an anodic potential to form a film. As a result, a mesh-structured layer composed of AgNPs with TA on their surface and electrochemically cross-linked via TA–TA covalent bonds at the Al(III)-free coordination sites is formed. The introduction of Al(III) ions bonded via coordination bonds with TA and their consecutive removal using sodium fluoride formed vacancies ready to bind Al(III) ions from the analyzed solution allowing their electrochemical sensing, as monitored by cyclic voltammetry, quartz crystal microbalance, and X-ray photoelectron spectroscopy. The film was employed for sensing of neurotoxic Al(III) in human serum. A linear correlation between the current value at 0.9 V and the concentration of Al(III) was obtained in the range between 0.10 and 0.298 μM.

In this work, carbon nanotubes (CNTs) are grown from Ni and Fe nanoparticles supported on a rough AlN surface. Although, identical experimental parameters are used during dewetting (island formation) via thermal treatment, Ni particles appear metallic and larger, whereas Fe particles are smaller and slightly oxidized. This difference in the nanoparticle chemical state and morphology reflects to CNTs during catalytic chemical vapor deposition in terms of their CNT growth mode and size: tip-growth mode for Ni catalyst with CNT diameters of up to 40 nm, whereas base-growth mode for Fe with CNT diameters typically less than 10 nm are observed.

The effect of helium on the tungsten microstructure was investigated first by exposure to a radio frequency driven helium plasma with fluxes of the order of 1 × 10(19) m(-2) s(-1) and second by helium incorporation via magnetron sputtering. Roughening of the surface and the creation of pinholes were observed when exposing poly- and nanocrystalline tungsten samples to low-flux plasma. A coating process using an excess of helium besides argon in the process gas mixture leads to a porous thin film and a granular surface structure whereas gas mixture ratios of up to 50% He/Ar (in terms of their partial pressures) lead to a dense structure. The presence of helium in the deposited film was confirmed with glow-discharge optical emission spectroscopy and thermal desorption measurements. Latter revealed that the highest fraction of the embedded helium atoms desorb at approximately 1500 K. Identical plasma treatments at various temperatures showed strongest modifications of the surface at 1500 K, which is attributed to the massive activation of helium singly bond to a single vacancy inside the film. Thus, an efficient way of preparing nanostructured tungsten surfaces and porous tungsten films at low fluxes was found.

In ITER, the first mirrors (FMs) are vulnerable to an in-vessel coolant leak which could severely diminish their optical properties. To understand the scope of this potential impact, several FM samples were exposed to a steam and humidity test simulating the event in ITER. Both rhodium and molybdenum mirrors, observed a loss in specular reflectivity as a result (the loss being greater for the Mo mirror). Their surfaces were tarnished with the development a thin Rh oxide and a thick Mo oxide (120–170 nm). This study focusses on capacitively coupled radio frequency (CCRF) plasma cleaning of steam ingressed (SI) FM samples and follow their optical recovery. Plasma cleaning experiments were performed with 13.56 MHz CCRF plasma using argon and/or hydrogen as process gas (with 230 eV ion energy). Initial and final reflectivity measurements, chemical surface analysis using in vaccuo X-ray photoelectron spectroscopy, scanning electron microscopy, focused ion beam and roughness measurements, were carried out for each sample to evaluate the cleaning efficiency. Using the plasma cleaning technique, it was possible to remove the SI induced contamination from the mirror surfaces and recover their optical properties to the pristine levels. Several ‘voids/inclusions’ were seen to arise along the grain boundaries as a result of the SI procedure. The concentration of these ‘voids/inclusions’ was observed to increase till a certain point followed by a decrease with increasing cleaning time. Keywords: ITER, First mirror, Steam ingress, Plasma cleaning, Reflectivity, XPS, Grain boundary

Molybdenum and rhodium are foreseen to be utilized in ITER for the light reflecting, plasma facing components called first mirrors (FMs). In this work, the plasma and impurity conditions which FMs are expected to be subjected to were simulated experimentally, while monitoring their reflectivity. Experiments include deuterium plasma exposure with tungsten–carbon and tungsten–aluminum impurities, where aluminum was employed as a proxy for beryllium. The surface composition and morphology of the mirrors were characterized with XPS and SEM. When carbon was present in the plasma, the molybdenum surface became carbidized, while this effect was not observed for rhodium. Aluminum impurities were deposited as oxides, whereas tungsten was either oxidized or carbidized depending on the presence of carbon in the plasma. SEM results show the deposits to be amorphous. The mirrors in erosion conditions showed no critical decrease in the reflectivity, whereas the degradation was severe in net deposition conditions involving carbon. Cleaning techniques have to be developed for mirrors in deposition conditions, which should be part of ITER’s routine operation.

This paper outlines a hierarchical Bayesian framework for interoception, homeostatic/allostatic control, and meta-cognition that connects fatigue and depression to the experience of chronic dyshomeostasis. Specifically, viewing interoception as the inversion of a generative model of viscerosensory inputs allows for a formal definition of dyshomeostasis (as chronically enhanced surprise about bodily signals, or, equivalently, low evidence for the brain's model of bodily states) and allostasis (as a change in prior beliefs or predictions which define setpoints for homeostatic reflex arcs). Critically, we propose that the performance of interoceptive-allostatic circuitry is monitored by a metacognitive layer that updates beliefs about the brain's capacity to successfully regulate bodily states (allostatic self-efficacy). In this framework, fatigue and depression can be understood as sequential responses to the interoceptive experience of dyshomeostasis and the ensuing metacognitive diagnosis of low allostatic self-efficacy. While fatigue might represent an early response with adaptive value (cf. sickness behavior), the experience of chronic dyshomeostasis may trigger a generalized belief of low self-efficacy and lack of control (cf. learned helplessness), resulting in depression. This perspective implies alternative pathophysiological mechanisms that are reflected by differential abnormalities in the effective connectivity of circuits for interoception and allostasis. We discuss suitably extended models of effective connectivity that could distinguish these connectivity patterns in individual patients and may help inform differential diagnosis of fatigue and depression in the future., Frontiers in Human Neuroscience, 10, ISSN:1662-5161

We report the self-assembly of aligned arrays of silver nanoparticles governed by a reaction–diffusion–precipitation process. The average 2 μm wide bands containing nanoparticles which are ∼160 nm in diameter are highly periodic with ∼0.9–3 μm spacing. Morphological and analytical characterization of the particles has provided crucial information for the formulation of a series of reactions explaining the band formation. We propose that the silver/silver oxide colloids in the bands turn into elemental silver particles upon UV illumination.

Cartilage matrix is a composite of discrete, but interacting suprastructures, i.e. cartilage fibers with microfibrillar or network-like aggregates and penetrating extrafibrillar proteoglycan matrix. The biomechanical function of the proteoglycan matrix and the collagen fibers are to absorb compressive and tensional loads, respectively. Here, we are focusing on the suprastructural organization of collagen fibrils and the degradation process of their hierarchical organized fiber architecture studied at high resolution at the authentic location within cartilage. We present electron micrographs of the collagenous cores of such fibers obtained by an improved protocol for scanning electron microscopy (SEM). Articular cartilages are permeated by small prototypic fibrils with a homogeneous diameter of 18 ± 5 nm that can align in their D-periodic pattern and merge into larger fibers by lateral association. Interestingly, these fibers have tissue-specific organizations in cartilage. They are twisted ropes in superficial regions of knee joints or assemble into parallel aligned cable-like structures in deeper regions of knee joint- or throughout hip joints articular cartilage. These novel observations contribute to an improved understanding of collagen fiber biogenesis, function, and homeostasis in hyaline cartilage.

The goal of this work was to investigate coated first mirrors under very harsh erosion conditions. Mock-up mirrors were exposed to high-flux hydrogen/argon plasma in the linear plasma facility Magnum-PSI. Rhodium (Rh) and molybdenum (Mo) coated mirrors of different coating thicknesses, with or without water cooling, exhibited different responses to this exposure. Failures of Rh films were demonstrated for 5 micron thick film, 1 micron film revealed 10% decrease in the specular reflectivity only in the exposed area. In comparison, water cooled Mo mock-ups showed a significant diffuse reflectivity on the entire surface leading to more than 50% specular reflectivity losses in the visible range. The losses for non-cooled Mo samples did not exceed 7% in the whole studied wavelength range of 250–2500 nm. Three phenomena were proposed to explain these results. First the mechanical properties of the films as characterized by scratch and hardness measurements as well as residual stress analysis measured by x-ray diffraction. Rh films showed a high compressive stress value of 2.5 ± 0.4 GPa leading to poor adhesion of the thick films deposited on stainless steel substrate due to the high amount of available energy per area stored in the unbuckled film i.e. 30$ ?> G 0 > 30 J m−2. It was confirmed by ANSYS simulation that the von Mises stress for the Rh coating was twice as high as that for the Mo coating due to different mechanical properties. Moreover, the maximum stress for thick Rh film (261 MPa) was higher than the critical buckling stress calculated with a buckle clamped Euler column model demonstrating the failure mode of the film. The second phenomenon was roughening of the mirror surface which was flux and temperature dependent, i.e. at low temperatures the surface would roughen randomly without any oriented surface morphology and at higher temperatures the surface diffusion constants would dominate the process and smoothen the surface. The last phenomenon was the significant oxidation and carbidization of the Mo surface even on the non-exposed area, as detected by x-ray photoelectron spectroscopy, leading also to a decrease in the reflectivity in the entire measured range, which was not observed for Rh film.

Titanium aluminum nitride ((Ti,Al)N) thin films are widely used as hard protective coating materials. Due to their remarkable tensile strength and elastic modulus carbon nanotubes (CNTs) are an ideal candidate as reinforcing components in such coatings. In this work (Ti,Al)N thin film were deposited on steel substrate by reactive magnetron sputtering and CNTs were grown on top by chemical vapor deposition (CVD). A second (Ti,Al)N film covered the CNTs in order to achieve a nanocomposite structure similar to reinforced concrete. The chemical evolution of the substrate, structure, morphology and growth of CNTs were analyzed by X-ray photoelectron spectroscopy and scanning electron microscopy. It was possible to achieve homogeneous dispersion of the CNTs within the matrix by adjusting the CVD time. Mechanical testing of the adherence and nanohardness of the (Ti,Al)N/CNT/(Ti,Al)N composite coating were performed by scratch and nanoindentation tests. The improvement of mechanical properties by CNT integration resulted in an increase of the hardness and of Young's modulus. (C) 2012 Elsevier B.V. All rights reserved.

Metallic mirrors are foreseen to play a crucial role for all optical diagnostics in ITER. Therefore, the development of reliable techniques for the production of mirrors which are able to maintain their optical properties in the harsh ITER environment is highly important. By applying magnetron sputtering and evaporation techniques, rhodium and molybdenum films have been prepared for tokamak tests. The films were characterised in terms of chemical composition, surface roughness, crystallite structure, reflectivity and adhesion. No impurities were detected on the surface after deposition. The effects of deposition parameters and substrate temperature on the resulting crystallite structure, surface roughness and hence on the reflectivity, were investigated. The films are found to exhibit nanometric crystallites with a dense columnar structure. Open boundaries between the crystallite columns, which are sometimes present after evaporation, are found to reduce the reflectivity as compared to rhodium or molybdenum references.

Iron catalyst in the form of a thin layer was deposited directly onto silicon wafers in order to grow carbon nanotubes by a chemical vapor deposition process. The chemical and morphological transformations undergone during the process by the iron were monitored in situ by photoelectron spectroscopy and ex situ by SEM. We found that the growth of carbon nanotubes was successful only when the iron catalyst was previously oxidized. Metallic iron transformed to embedded iron silicide structures, unable to initiate nanotube growth. On the other hand, pre-oxidized iron led to the formation of superficial particles and showed only a partial conversion to silicide, which resulted in carbon nanotube growth, even at very low pressures.

The preparation and detailed characterization of sub-stoichiometric rhodium oxide films prepared by magnetron sputtering at room temperature have been carried out on silicon substrates. Effects of the oxygen gas flow ratio on chemical bonding state, optical reflectivity and crystallinity were investigated using XPS, reflectivity measurements, XRD and SEM. For oxygen flow ratios higher than 2%, the films become amorphous with high resistivity (1.5 × 10 −5 Ω m) indicating semiconducting properties. The same experiments were performed at 300 °C and even with high oxygen gas flow ratio the films always have a metallic component. Moreover, for high fractions of oxygen in the plasma, films are always sub-stoichiometric.

In this letter, we report on the use of tin as an effective surfactant material for silver growing on silicon oxide. We observed that submonolayers of Sn pre-deposited on SiO 2 result in earlier film coalescence and formation of smoother Ag layers. We suggest that Sn atoms reduce the Ag-adatom mobility resulting in experimentally observed increased island density and decreased film roughness. Angle-resolved X-ray photoelectron spectroscopy reveals that Sn remains under the Ag layer giving circumstantial evidence that at later stages of Ag film growth Sn does not influence the interlayer transport.

Preparation and detailed characterization of metallic rhodium films prepared by magnetron sputtering on silicon substrates have been carried out. Different deposition conditions such as gas pressure, deposition rate and substrate temperature were investigated. The films were characterized by XPS, SEM, XRD, AFM and reflectivity measurements. No impurities were detected on the surface after deposition. The films have a low roughness and their structure exhibit nanometric crystallites with a dense columnar structure. Amongst all investigated parameters, only the gas pressure during deposition was observed to have an influence on the optical properties of the film. Otherwise, the measured reflectivity is close to the reflectivity calculated from optical constants of pure rhodium films.

The final oxidation state of iron particles, used as catalysts for the growth by chemical vapor deposition of carbon nanotubes, was investigated by means of in situ photoelectron spectroscopy. Although the chemical evolution of the catalyst during the process is known to depend strongly on the nature of the substrate, we could address nanotube growth from metallic and fully oxidized particles grown onto the same type of substrate (Al2O3). While oxide particles promoted carbon nanotube growth efficiently, metallic particles of roughly the same size, known to be active onto other kinds of substrates, showed a very poor performance.

In the present study, we investigate the influence of low energy ion bombardment on nucleation and growth of thin silver films on silicon oxide by in situ photoelectron spectroscopy (PES) combined with specific resistivity measurements. Thermally grown thin silicon oxide films were exposed to a low temperature argon plasma for different time intervals resulting in changes in surface chemical composition as monitored by angle-resolved X-ray photoelectron spectroscopy (ARXPS). We demonstrate that irradiation of the oxide surface with low energy ions results in substantially changed nucleation of silver. Furthermore, silver films deposited on plasma treated oxide tend to have lower resistivity which is attributed to the effect of reduced grain boundary and surface roughness.

Several metal surfaces, such as titanium, aluminum and copper, were exposed to highfluxes (in the range of 1023m−2s−1) of low energy(

To avoid reflectivity losses in ITER’s optical diagnostic systems, on-site cleaning of metallic first mirrors via plasma sputtering is foreseen to remove deposit build-ups migrating from the main wall. In this work, the influence of aluminium and tungsten deposits on the reflectivity of molybdenum mirrors as well as the possibility to clean them with plasma exposure is investigated. Porous ITER-like deposits are grown to mimic the edge conditions expected in ITER, and a severe degradation in the specular reflectivity is observed as these deposits build up on the mirror surface. In addition, dense oxide films are produced for comparisonswithporousfilms. Thecomposition,morphologyandcrystalstructureofseveralfilmswerecharacterizedbymeans of scanning electron microscopy, x-ray photoelectron spectroscopy, x-ray diffraction and secondary ion mass spectrometry. The cleaning of the deposits and the restoration of the mirrors’ optical properties are possible either with a Kaufman source or radio frequency directly applied to the mirror (or radio frequency plasma generated directly around the mirror surface). Accelerating ions of an external plasma source through a direct current applied onto the mirror does not remove deposits composed of oxides. A possible implementation of plasma cleaning in ITER is addressed.

We studied the interaction of adsorbed thiol molecules with gold nanoparticles as a function of the mean particle size. The results obtained from MXPS (monochromated X-Ray Photoelectron Spectroscopy) measurements showed that attachment of the thiol sulfur headgroup onto the cluster surface leads to a positive binding energy shift in the Au 4f core-level. The absence of line width broadening upon adsorption indicates that these changes affect the whole particle and not only the particle surface, where the actual Au–S bond is located. The positive binding energy shift depends on the cluster size and increases with decreasing diameter. A maximum shift of 0.41 eV could be measured for the smallest particles (∼1 nm). The valence band exhibited positive binding energy shifts similar to the Au 4f core-levels, but smaller in absolute values. Changes in the valence band shape were interpreted as re-hybridization of Au 5d electrons due to the creation of Au–S bonds. Furthermore, we observed a disappearance of the Fermi edge upon thiol adsorption, which we attribute to a sulfur-induced metal-insulator-transition of the gold cluster.

Carbon nanotubes grown by chemical vapor deposition have revealed differences in growth rate and characteristics depending on the underlying buffer layer. As determined by in situ photoelectron spectroscopy, iron catalyst deposited onto Si substrates covered with Al2O3, TiN, or TiO2 underwent different chemical changes during annealing and exposure to C2H2 as function of buffer layer. Formation of thin tubes (2−4 walls) and fast growth rate were associated with conversion of Fe onto FeO particles on Al2O3 layers. On the other hand, thick multiwalled tubes (more than 20 walls) grew from pure Fe particles formed onto TiN and TiO2 layers. The influence of different buffer layers is attributed to a combination of chemical and morphological changes induced in the catalyst due to catalyst-substrate interaction.

Carbon nanotubes (CNTs) have been grown by chemical vapor deposition in a vacuum chamber equipped with in situ photoelectron spectroscopy technique that allows for precise characterization of the chemical state of substrate and catalyst before the CNTs growth. The CNTs were grown onto Si wafers covered with thin buffer layers of Al, Al 2 O 3 , TiN, and TiO 2 , using Fe as catalyst. Marked differences were observed both in growth rate and nanotube characteristics, as determined by SEM, TEM and micro-Raman spectroscopy, depending on the choice of buffer layer.

Thin nanostructured films of TiN–Ag are deposited by a plasma vapour process consisting of co-sputtering of Ti and Ag from three magnetrons in an Ar–N2 gas mixture. The coatings are characterized by in situ photoelectron spectroscopy, energy-filtered transmission electron microscopy and scanning electron microscopy. The dependence of the film structure and silver cluster distribution on total silver content, substrate biasing and substrate temperature was investigated.

The detailed characterizations of rhodium/tungsten films prepared by co-deposition using a dual magnetron sputtering have been carried out on silicon substrates at room temperature. Effects of the tungsten incorporated in the film on the chemical bonding state, optical reflectivity and crystallinity were investigated using X-ray photoelectron spectroscopy (XPS), reflectivity measurements, X-rays diffraction (XRD) and scanning electron microscopy (SEM). The incorporation of tungsten changes the films crystalline structure i.e. leading to Rh3W formation. The reflectivity of the films decreases linearly with the decrease of rhodium concentration. XPS and ultraviolet photoemission spectroscopy (UPS) measurements show a positive shift of the core level binding energy of rhodium which is coupled to a shift of the Rh d-band DEd away from the Fermi level. Opposite shifts are observed for tungsten.

In its full sense, perception rests on an agent’s model of how its sensory input comes about and the inferences it draws based on this model. These inferences are necessarily uncertain. Here, we illustrate how the hierarchical Gaussian filter (HGF) offers a principled and generic way to deal with the several forms that uncertainty in perception takes. The HGF is a recent derivation of one-step update equations from Bayesian principles that rests on a hierarchical generative model of the environment and its (in)stability. It is computationally highly efficient, allows for online estimates of hidden states, and has found numerous applications to experimental data from human subjects. In this paper, we generalize previous descriptions of the HGF and its account of perceptual uncertainty. First, we explicitly formulate the extension of the HGF’s hierarchy to any number of levels; second, we discuss how various forms of uncertainty are accommodated by the minimization of variational free energy as encoded in the update equations; third, we combine the HGF with decision models and demonstrate the inversion of this combination; finally, we report a simulation study that compared four optimization methods for inverting the HGF/decision model combination at different noise levels. These four methods (Nelder-Mead simplex algorithm, Gaussian process-based global optimization, variational Bayes and Markov chain Monte Carlo sampling) all performed well even under considerable noise, with variational Bayes offering the best combination of efficiency and informativeness of inference. Our results demonstrate that the HGF provides a principled, flexible, and efficient - but at the same time intuitive - framework for the resolution of perceptual uncertainty in behaving agents.

We have investigated the formation of various carbon nanostructures using extreme plasma fluxes up to four orders of magnitude larger than in conventional plasma-enhanced chemical vapor deposition processing. Carbon nanowalls, multi-wall nanotubes, spherical nanoparticles and nanotips are among the structures detected with electron microscopy methods. Precursor injection or surface pretreatment were not required for the synthesis of the nanostructures. Preliminary experiments with varied plasma composition, sample bias and surface temperature have demonstrated the potential for optimizing the growth of the nanostructures in the current experimental set-up.

Titanium aluminum nitride films (Ti1−xAlxN) have been deposited by reactive magnetron cosputtering. Elemental compositions of these films have been determined by core level photoelectron spectroscopy. Scanning electron microscopy reveals a columnar film growth. This is also reflected by the topography of film surfaces as studied by atomic force microscopy. By x-ray diffraction a crystalline atomic structure is revealed. Single phase samples can be obtained, consisting of the substitutional solid solution (Ti, Al)N. Crystallites show preferential orientation. The optical properties of these films have been investigated by spectrophotometry in the UV-VIS-NIR wavelength range. Depending on the elemental composition, the optical constants vary from metallic to dielectric behavior. For film compositions with x

Development and adhesion of infection structures of the grapevine powdery mildew fungus. U~cinu/a necator (Schw.) Burr.. were investigated during the early stages of leaf colonization. Light microscopy showed that pri­ mary appressoria occurred 3.5 h post inoculation (p.i.) and that hyphae on the leaf surface, indicative of successful host colonization, appeared 14 h p.i. Low temperature scanning electron microscopy revealed deposits of extracellular mate­ rial at the contact zone of fungal structures and plant cuticle, suggesting firm attachment of the pathogen. To investi­ gate whether or not esterase or cutinase activity is involved in establishing the fungus on the host cuticle, histochemical assays and inhibitor studies were performed. Results indicated that esterase activity was associated with conidia and infection structures. A single fungal extracellular protein was identified as a cutinase by its ability to hy­ drolyze 3H-cutin. Probing Southern blots of genomic DNA of U necalor, Magnaporlhe grisea, and Fusarium so/ani fsp. pisi with the cutinase gene of F so/ani fsp. pisi suggested that the cutinase gene of U necalor shares only lim­ ited sequence similarities with the cutinase genes of the other fungi investigated. Adhesion assays showed that the pres­ ence of esterase-cutinase inhibitors on the cuticle did not significantly affect adhesion. The role of the enzyme in fungal adhesion is discussed.

Thermal reduction of tungsten oxide nanoclusters supported on thin silicon and aluminum oxide films and ranging in size from 2 to 8 nm was studied by in situ X-ray photoelectron spectroscopy. We observed that with a decrease in size oxide clusters demonstrate enhanced resistance to the oxide reduction when heated in vacuum. The effect is presumed to be related to the point defects that serve as nucleation sites in the oxide reduction process. It is suggested that due to the increased Laplace pressure small clusters contain lower defect density thus making them less susceptible to the thermal reduction. Preamorphization of the oxide particles by low-energy ion bombardment demonstrated a lowering of oxide decomposition temperature thus supporting the inference on the defect stimulated oxide reduction. These results provide a novel model system to understand the reduction behavior of bulk tungsten oxides and might be of crucial relevance for applications where the use of clusters is of special importance.

The combined effect of hydrogen plasma exposure and surface heating, either continuous or by short laser pulses (5 ns), on the surface morphology of rhodium layers has been studied. Investigations were performed by reflectivity measurements, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM). While surfaces exposed at room temperature exhibit little modifications, strong surface changes are observed for surface temperatures higher than 250 °C. At 500 °C, the plasma exposed surface exhibits a nanoscale structure (50–100 nm) with a high level of porosity and a low reflectivity. Additional laser irradiation of the surface strongly enhances the observed surface damage. Localized surface melting is observed with craters extending deep into the substrate together with a dense network of voids.

A laser ablation system has been constructed and used to determine the damage threshold of stainless steel, rhodium and single-, poly- and nanocrystalline molybdenum in vacuum, at a number of wavelengths between 220 and 1064 nm using 5 ns pulses. All materials show an increase of the damage threshold with decreasing wavelength below 400 nm. Tests in a nitrogen atmosphere showed a decrease of the damage threshold by a factor of two to three. Cleaning tests have been performed in vacuum on stainless steel samples after applying mixed Al/W/C/D coatings using magnetron sputtering. In situ XPS analysis during the cleaning process as well ex situ reflectivity measurements demonstrate near complete removal of the coating and a substantial recovery of the reflectivity. The first results also show that the reflectivity obtained through cleaning at 532 nm may be further increased by additional exposure to UV light, in this case 230 nm, an effect which is attributed to the removal of tungsten dust from the surface., 19 pages, 16 figures

Detailed characterizations of rhodium/silicon films prepared by co-deposition using magnetron sputtering have been carried out on silicon substrates at room temperature up to 900 degrees C. The properties of the films were investigated using XPS/UPS, XRD, SIMS, SEM and AFM techniques. It should be emphasized that XPS/UPS measurements are carried out without breaking the vacuum to avoid any contamination of the film. Up to 500 degrees C an interdiffusion between the oxidized silicon wafer and the deposited Rh/Si film occurred leading to hole formation in the entire film at 900 degrees C. Diffraction patterns for the compounds Rh(2)Si, Rh(5)Si(3), RhSi and Rh(3)Si(4) were measured. Upon annealing the covalent character is increased and for the samples forming the compound RhSi the valence band structure is markedly changed. Depth profiling (XPS and SIMS) reveals a stable composition in the bulk of the film. For these measurements the silicon-rich alloy in the interfacial layer is probably an effect of sputtering, by implanting the Rh atoms into the silicon substrate. A previously reported negative shift for the compound Rh(5)Si(3) could be connected to the sample preparation, as sputtering of the surface is reducing the silicon content and inducing a glassy state. For the first phase Rh(2)Si formed on the rhodium-rich side the shift in binding energy is unclear, for all the other compounds encountered in this work a positive shift relative to pure rhodium was found.

Microlite, a Ta-rich member of the pyrochlore group, occurs in 440 Ma old lithium pegmatites in Mozambique and exhibits a pronounced growth zoning, with a U-free core surrounded by a U-rich rim (UO2≤ 17 wt%). Subsequent to the uplift of the host rock, microlite was subjected to intense low-temperature alteration during which Na, Ca and F were leached from the microlite crystals. This alteration, resulting from exposure to tropical conditions, also led to localized redistribution of radiogenic Pb (formation of plumbomicrolite) and to hydration of microlite, but U remained immobile. The low-temperature alteration effects are only observed in the U-rich rim, which is characterized by abundant microfractures. As demonstrated by electron diffraction images and powder X-ray patterns, the U-rich rim is largely metamict. Our investigation illustrates the importance of natural analogues in evaluating the durability of pyrochlore-based nuclear waste-form materials over geologic time.

ICorrosion of zirconolite in a closed system at elevated temperature and pressure for various fluid compositions has been investigated by several analytical techniques. Together with previous studies, the results indicate a weak corrosion below 250° C at 5 MPa, Above 400° C, secondary TiO2 phases crystallize in acidic and neutral fluids on the corroded surfaces and in near-surface pores, At 550° C and above, zirconolite starts to be replaced by perovskite and “calzirtite” in basic fluids. Our results indicate that zirconolite is reasonably durable in acidic. neutral and basic fluids up to 500° C and 50 MPa which corresponds to deep borehole conditions.

Objectives. Dentin bonding samples are generally observed in the high vacuum chamber of an electron microscope only after completion of the bonding procedure fixation, dehydration and drying of the specimens. The purpose of this study was to observe the effect of each step in the application of various one-bottle dentin bonding agents (DBA) using cryopreparation followed by low-temperature scanning electron microscopy (LTSEM). Methods. Prime&Bond 2.1 (P&B 2.1), Coltene Experimental (Exp.) and Syntac Single Component (Syntac SC) were applied onto perfused dentin of extracted, human third permanent molar teeth. After acid-etching, rinsing and drying, and following the application of the respective resins, the teeth were fractured at random and plunge-frozen in liquid nitrogen before examination under LTSEM. As this method preserves the state of the treated surface at the moment when it is frozen, each step of the application of the DBA can be observed as if it were a ‘real-time’ procedure. Results. Acid-etching the dentin resulted in the removal of the smear layer for all materials tested. Those one-bottle DBAs which recommend the application of two consecutive resin layers (P&B 2.1 and Syntac SC) showed incomplete saturation of the dentinal surface after application of the first layer. With Syntac SC the incomplete saturation was more pronounced than with P&B 2.1. The use of Exp. resulted in a much more homogeneous coverage of the dentin despite only one layer of resin having been applied. Conclusion. It is concluded that cryo-preparation followed by LTSEM appears to be a method which allows each stage of the application of DBA to be evaluated.

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Metallic first mirrors (FMs) are foreseen to play a crucial role for all optical diagnostics in ITER. It is highly important for the FMs to maintain a good reflectivity both in erosion and deposition zones in the harsh ITER environment. Molybdenum mirrors, which are important candidates for the FMs, exhibit a reflectivity spectrum different from that of bulk molybdenum after exposure to low temperature (4–5 eV) deuterium plasma. This difference is mainly due to the presence of deuterium and deuterium-induced defects in the metal. The results presented show that these reflectivity changes are similar for single and nanocrystalline molybdenum mirrors. Moreover, exposure of magnetron sputtered nanocrystalline molybdenum films to deuterium plasma revealed that after a certain deviation of the spectrum has been reached, the reflectivity remains constant upon further exposure. Exposures were carried out in a range of fluences corresponding to up to 18 ITER discharges in equatorial ports and 38 discharges in the upper ports in the first wall positions. Constant conditions of −200 V bias and 150 °C temperature were maintained on the samples. Further exposures performed in a tokamak result in reflectivity changes that are comparable to those obtained with deuterium plasma exposure. No mechanical damage, such as blistering and increase in roughness, is observed on the coated molybdenum films upon any of the mentioned exposures. The complex permittivity of the exposed molybdenum is determined from ellipsometry measurements and corroborated with core and valence level photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy and surface resistivity measurements.

Spectrally selective absorption coatings for solar thermal energy conversion applications should exhibit a high absorptance in the 0.4 - 1 micrometers wavelength range of the electro magnetic spectrum. Additionally, a low emittance in the thermal radiation range has to be attained. Niobium films displaying such optical properties were obtained by sputtering onto Si(100) and Mo substrates and suitable variation of the preparation parameters. The sputtered films were characterized by in situ photoelectron spectroscopy, and not in situ optical reflectometry and scanning electron microscopy (SEM). Emittance and absorptance were determined as function of temperature by the `dynamical vacuum technique.' It is found in particular that the as prepared films show a dendritic surface structure as revealed by SEM. In addition, the wavelength of transition from highly absorbing to reflecting character is shown to correlate with the inter-dendrite distance.

1. Department of Biophysical and Electronic Engineering, University of Genova, Italy; 2. M.E. Muller Institute for Structural Biology, Biozentrum University of Basel, Switzerland; 3. Department of Orthopaedic Surgery & Traumatology, Kantonsspital, Bruderholz/Basel, Switzerland; 4. Laboratory for Tissue Engineering, Department of Surgery & Research, University Hospital of Basel, Switzerland; 5. Center for Microscopy, University of Basel, Switzerland; 6. Institute of Microtechnology, University of Neuchâtel, Switzerland.

We have characterized the thickness and effective refractive index of carbon nanotube forests by fitting reflectance measurements in the visible and near infrared ranges. The measurements were performed with polarized light. An effective medium layer consisting of a mixture of graphite and air was used to simulate the nanotube film. The proposed model accurately described the behaviour of the reflected s-polarized component (Rs), which allowed for the precise determination of the thickness and porosity of the films, in very good agreement with SEM measurements of film thickness. The p-polarized component (Rp), on the other hand, could not be described in terms of the developed model. In badly aligned samples, where there is a mixture of Rs and Rp behaviour, the model fails to fit the Rs component as well. This effect can therefore be taken as an indirect indication of lack of alignment in the samples.

The nucleation and interface formation between Ag films and native silicon oxide have been studied with x-ray and ultraviolet photoelectron spectroscopies. Silver was deposited stepwise onto silicon native oxide by pulsed arc deposition technique onto grounded and biased substrates resulting in kinetic energy of incident silver ions of 95 and 720eV, respectively. We show that an increase in the kinetic energy of silver ions leads to more homogeneous nucleation and earlier coalescence of Ag films due to surface defect generation and preferential sputtering of oxygen. In addition, deposition from high energy beam results in the formation of an extended transition layer containing a mixture of Ag and Si oxide that might be beneficial in improving adhesion of Ag films.

Bufuralol, debrisoquine, and dextromethorphan are three prototype substrates of the common genetic deficiency of oxidative drug metabolism in man known as debrisoquine/sparteine-type polymorphism. We describe assays for the in vitro metabolism of (+)- and (-)-bufuralol, debrisoquine, and dextromethorphan in human liver microsomes and reconstituted purified cytochrome P-450 isozymes. These assays combine nonextractive sample preparation by precipitation of protein with perchloric acid with reversed-phase inorganic ion-pair HPLC and fluorescence detection. The minimal detectable levels of the major metabolites formed are 1'-hydroxybufuralol, 0.1 ng/ml; 4-hydroxydebrisoquine, 0.8 ng/ml; and dextrorphan, 0.1 ng/ml. Formation of these metabolites is linear for at least 45 min and between 1 and 100 micrograms of microsomal protein. Comparative kinetic analysis of the three monooxygenase reactions in human liver microsomes revealed an apparent biphasicity of (+)- and (-)-bufuralol 1'-hydroxylation and dextromethorphan O-demethylation but monophasic formation of 4-hydroxydebrisoquine in the substrate concentration range (less than 1 mM) studied. These data, in combination with those obtained by purified human cytochrome P-450 isozymes indicate the involvement of the same enzyme in the metabolism of all three substrates investigated. However, additional and distinct activities contribute to the metabolism of (+)- and (-)-bufuralol and dextromethorphan.

The behavior of rhodium film mirrors with different crystal structure and morphology toward a deuterium plasma is presented. The specular reflectivity of rhodium films was monitored before, during and after exposure. To understand the reflectivity behavior of the rhodium films during exposure, samples were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and atomic force microscopy. Crystal structure and morphology of rhodium films strongly affect the change of the specular reflectivity during deuterium plasma exposure. In particular, films with few nm crystallite size and granular-like morphology prevent the reflectivity degradation, probably as a consequence of the inhibition of rhodium deuteride sub-superficial layer formation.

The influence of the substrate potential with respect to the plasma on the morphology of reactively sputtered TiN thin films on Si(100) has been investigated. It is well known that the film quality with respect to grain size and distribution can be improved by applying a negative substrate bias to increase energetic ion bombardment. For large-area applications, however, a grounded substrate is very much desirable. Therefore, a technique has been developed to deposit films with comparably improved morphology on grounded substrates by means of a so-called “plasma electrode.” Grain size and distribution have been analyzed by top- and side-view scanning electron microscopy. To adjust the parameters for the TiN deposition we have used in situ photoelectron spectroscopy as the process control.