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ZnO nanopillars are often grown on various substrates by catalytic growth processes through a vapor-liquid-solid (VLS) mechanism. However, on silicon substrates, even with the catalyzed growth processes, it is still very difficult to... more
ZnO nanopillars are often grown on various substrates by catalytic growth processes through a vapor-liquid-solid (VLS) mechanism. However, on silicon substrates, even with the catalyzed growth processes, it is still very difficult to obtain highly oriented ZnO nanopillar arrays. In ...
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The mechanisms of sterilization and decontamination of surfaces are compared in direct and post discharge plasma treatments in two low-pressure reactors, microwave and inductively coupled plasma. It is shown that the removal of various... more
The mechanisms of sterilization and decontamination of surfaces are compared in direct and post discharge plasma treatments in two low-pressure reactors, microwave and inductively coupled plasma. It is shown that the removal of various biomolecules, such as proteins, pyrogens or peptides, can be obtained at high rates and low temperatures in the inductively coupled plasma (ICP) by using Ar/O2 mixtures.
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A Reply to the Comment by Ing-Shouh Hwang and Tien T. Tsong.
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Au/TiO 2/Ru(0 0 0 1) model catalysts and their interaction with CO were investigated by scanning tunneling microscopy and different surface spectroscopies. Thin titanium oxide films were prepared by Ti deposition on Ru(0 0 0 1) in an O 2... more
Au/TiO 2/Ru(0 0 0 1) model catalysts and their interaction with CO were investigated by scanning tunneling microscopy and different surface spectroscopies. Thin titanium oxide films were prepared by Ti deposition on Ru(0 0 0 1) in an O 2 atmosphere and subsequent annealing in O 2. By optimizing the conditions for deposition and post-treatment, smooth films were obtained either as fully oxidized TiO 2 or as partly reduced TiO x, depending on the preparation conditions. CO adsorbed molecularly on both oxidized and reduced TiO 2, with slightly stronger bonding on the reduced films. Model catalyst surfaces were prepared by depositing submonolayer quantities of Au on the films and characterized by X-ray photoelectron spectroscopy and scanning tunneling microscopy. From X-ray photoelectron spectroscopy, a weak interaction between the Au and the TiO 2 substrate was found. At 100 K CO adsorption occurred on both the TiO 2 film and on the Au nanoparticles. CO desorbed from the Au particles with activation energies between 53 and 65 kJ/mol, depending on the Au coverage. If the Au deposit was annealed to 770 K prior to CO exposure, the CO adsorption energy decreased significantly. STM measurements revealed that the Au particles grow upon annealing, but are not encapsulated by TiO x suboxides. The higher CO adsorption energy observed for smaller Au coverages and before annealing is attributed to a significantly stronger interaction of CO with mono- and bilayer Au islands, while for higher particles, the adsorption energy becomes more bulk-like. The implications of these effects on the known particle size effects in CO oxidation over supported Au/TiO 2 catalysts are discussed.
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Selecting appropriate ways of bringing engineered nanoparticles (ENP) into aqueous dispersion is a main obstacle for testing, and thus for understanding and evaluating, their potential adverse effects to the environment and human health.... more
Selecting appropriate ways of bringing engineered nanoparticles (ENP) into aqueous dispersion is a main obstacle for testing, and thus for understanding and evaluating, their potential adverse effects to the environment and human health. Using different methods to prepare (stock) dispersions of the same ENP may be a source of variation in the toxicity measured. Harmonization and standardization of dispersion methods applied in mammalian and ecotoxicity testing are needed to ensure a comparable data quality and to minimize test artifacts produced by modifications of ENP during the dispersion preparation process. Such harmonization and standardization will also enhance comparability among tests, labs, and studies on different types of ENP. The scope of this review was to critically discuss the essential parameters in dispersion protocols for ENP. The parameters are identified from individual scientific studies and from consensus reached in larger scale research projects and internatio...
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ABSTRACT Nanotechnology can contribute to the development of innovative applications in the agriculture, food and feed sector by e.g. enabling improved delivery of nutrients or increased efficacy of agrichemicals. It is expected that... more
ABSTRACT Nanotechnology can contribute to the development of innovative applications in the agriculture, food and feed sector by e.g. enabling improved delivery of nutrients or increased efficacy of agrichemicals. It is expected that applications will increase in the near future and may therefore become a relevant source of human exposure to nanomaterials (NM). To gain more up-to date information, RIKILT and the Joint Research Centre (JRC) were commissioned by the European Food Safety Authority (EFSA) to prepare an inventory of currently used and reasonably foreseen applications of NM in agriculture and food/feed production and carried out a review of regulatory aspects concerning NM in both EU and non-EU countries. An analysis of the information records in the inventory shows that nano-encapsulates, silver and titanium dioxide are the most frequent type of NM listed and that food additives and food contact materials are the most frequent types of application. A comparison between marketed applications and those in development indicates a trend from inorganic materials (e.g. silver) towards organic materials (nano-encapsulates, nanocomposites). Applications in novel food, feed additives, biocides and pesticides are currently mostly at a developmental stage. The review of EU and non-EU legislation shows that currently a few EU legal acts incorporate a definition of a nanomaterial and specific provisions for NM, whereas in many non-EU countries a broader approach is applied, which mainly builds on guidance for industry.
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Bio-functionalized surfaces were prepared to study the adherence and differentiation capacity of neural stem cells derived from human umbilical cord blood (HUCB-NSC). Cell growth platforms containing arranged arrays of adhesive molecules... more
Bio-functionalized surfaces were prepared to study the adherence and differentiation capacity of neural stem cells derived from human umbilical cord blood (HUCB-NSC). Cell growth platforms containing arranged arrays of adhesive molecules were created by microcontact printing on a biologically inert surface. Biomolecules used to prepare microarray platforms included the extracellular matrix protein fibronectin and the polyaminoacid poly-L-lysine. HUCB-NSC plated on microplatforms at various serum conditions showed serum and molecule type dependent capacity for adhesion and differentiation. Poly-L-lysine allowed the maintenance of stem-like non differentiated cells attached to the surface, whereas fibronectin promoted spreading and neural commitment. Serum deprivation did not influence the attachment of HUCB-NSC to fibronectin, but significantly enhanced the attachment to poly-L-lysine and promoted dBcAMP induced neuronal differentiation. A bio-pattern of squares with interconnecting ...
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Nanotechnology is of increasing significance. Curation of nanomaterial data into electronic databases offers opportunities to better understand and predict nanomaterials' behaviour. This supports innovation in, and regulation of,... more
Nanotechnology is of increasing significance. Curation of nanomaterial data into electronic databases offers opportunities to better understand and predict nanomaterials' behaviour. This supports innovation in, and regulation of, nanotechnology. It is commonly understood that curated data need to be sufficiently complete and of sufficient quality to serve their intended purpose. However, assessing data completeness and quality is non-trivial in general and is arguably especially difficult in the nanoscience area, given its highly multidisciplinary nature. The current article, part of the Nanomaterial Data Curation Initiative series, addresses how to assess the completeness and quality of (curated) nanomaterial data. In order to address this key challenge, a variety of related issues are discussed: the meaning and importance of data completeness and quality, existing approaches to their assessment and the key challenges associated with evaluating the completeness and quality of c...
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Research Interests: Condensed Matter Physics, Quantum Physics, Surface Science, Kinetics, Carbon, and 15 moreMorphology, Carbon Monoxide, Surface topography, Desorption, Surface Structure, Roughness, Surface States, Work Function, Temperature Programmed Desorption, Chemical Properties, Potential Energy Surface, TDS, Absorption Spectra, C, and Adsorption kinetic
ABSTRACT The influence of CO on the adsorption and decomposition of toluene has been studied in the coadsorption system prepared by saturating the well-defined ( with toluene at 200 K, which then contains about 4.5 CO molecules to 1... more
ABSTRACT The influence of CO on the adsorption and decomposition of toluene has been studied in the coadsorption system prepared by saturating the well-defined ( with toluene at 200 K, which then contains about 4.5 CO molecules to 1 toluene molecule. The initial decomposition steps of toluene are drastically modified by the high density of coadsorbed CO in this layer. Utilizing HREELS, TPD, ΔΦ, and LEED, and employing partially deuterated toluene, the first dissociation step of toluene and the formation of a C7H7-benzyl species can be identified around 320 K, 100 K lower than in the pure system, which is attributed to a destabilizing influence of CO on toluene. This η7(π + σ) bonded (C7H7) benzyl species is the major decomposition product between 280 and 350 K. In contrast to the behavior in the pure toluene layer, two of the methyl hydrogen atoms desorb at a clearly lower temperature than the ring hydrogens, and the abstraction of the first methyl-H which leads to the benzyl species is clearly separated from the others, so that this species can be studied spectroscopically. The thermal desorption data suggest a C7H6 species as a further intermediate, for which no direct proof can be derived from HREELS, however. Two different CO species with vCO ≈ 1985 cm−1 and 1675–1750 cm−1, respectively, are observed in the coadsorbate layer; the one with the lower CO stretch frequency transforms into the other one by 320 K, simultaneously with the transition toluene → benzyl. Some data on the thermal evolution of adsorbed toluene coadsorbed with oxygen are also reported which show similar, although not quite as distinct features, albeit at lower coadsorbate coverage ratio. This supports the assumption that the change of reactivity is due to an electronic effect of the electronegative coadsorbates on adsorbed toluene which may contain inductive and field-induced contributions.
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The results of an IR study on the interaction of CO/O 2 gas mixtures with planar Au/TiO 2 model catalysts at elevated pressures and at room temperature are presented. The model catalysts were prepared by deposition of a flat titania film... more
The results of an IR study on the interaction of CO/O 2 gas mixtures with planar Au/TiO 2 model catalysts at elevated pressures and at room temperature are presented. The model catalysts were prepared by deposition of a flat titania film on a Ru(0 0 0 1) substrate and ...
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Structure, chemical composition and thermal stability of TiOx films with a thickness of up to 3ML grown on a Ru(0001) substrate were investigated by scanning tunneling microscopy, X-ray photoelectron spectroscopy and Auger electron... more
Structure, chemical composition and thermal stability of TiOx films with a thickness of up to 3ML grown on a Ru(0001) substrate were investigated by scanning tunneling microscopy, X-ray photoelectron spectroscopy and Auger electron spectroscopy. The films were prepared by evaporation of Ti in 10−7mbar O2 onto Ru(0001) at 640K, followed by annealing in 10−7mbar O2 or in UHV at temperatures between 700K and 1000K. Depending on the deposition and post-annealing conditions, we find several different structures of the Ti oxide, with the layers post-annealed in an O2 environment being generally better defined than those post-annealed in vacuum. The layers consist of triangular units which coalesce upon annealing. O2 annealing of monolayer films leads to an oxygen deficient TiO2 layer. Annealing to 900–1000K changes the structure and composition of the film, a coincidence structure with a Moiré pattern is observed upon O2 annealing.
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We report results of a scanning tunneling microscopy and X-ray photoelectron spectroscopy study on the interaction of tetraethoxysilane (TEOS), a precursor for chemical vapor deposition of silicon dioxide, with Si(111)-(7×7) at room... more
We report results of a scanning tunneling microscopy and X-ray photoelectron spectroscopy study on the interaction of tetraethoxysilane (TEOS), a precursor for chemical vapor deposition of silicon dioxide, with Si(111)-(7×7) at room temperature. Under these conditions the interaction of TEOS with the surface is predominantly dissociative. The main adsorption products are ethyl- and triethoxysiloxane groups, which probably evolve in a
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The coadsorption of CO and hydrogen on a structurally well-defined Pt(35)Ru(65)/Ru(0001) monolayer surface alloy and, for comparison, on Ru(0001) were investigated by temperature programmed desorption (TPD) and infrared reflection... more
The coadsorption of CO and hydrogen on a structurally well-defined Pt(35)Ru(65)/Ru(0001) monolayer surface alloy and, for comparison, on Ru(0001) were investigated by temperature programmed desorption (TPD) and infrared reflection absorption spectroscopy (IRAS). The data reveal distinct modifications in the hydrogen adsorption behavior and also in the CO adsorption properties compared to adsorption of the individual components both on the mono-metallic and on the bimetallic surface. These modifications are discussed on an atomic scale, in a picture that involves adsorbate-adsorbate interactions and site-specific variations in the (local) adsorption properties of the bimetallic surface, due to electronic ligand and strain effects and geometric ensemble effects.
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Research Interests: Engineering, Scanning Electron Microscopy, Atomic Force Microscopy, Surface Roughness, Ultraviolet, and 9 moreThin Film, Physical sciences, Refractive Index, UV/Vis spectroscopy, Room Temperature, Fourier transform infrared spectroscopy, Ion Beam, X Ray Photoelectron Spectroscopy, and Fourier transform infrared
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The influence of pre-adsorbed hydrogen on the adsorption of CO on well-defined PtRu/Ru(0001) surface alloys and the modification of the adsorption properties of both adsorbate species due to coadsorption was studied by a combination of... more
The influence of pre-adsorbed hydrogen on the adsorption of CO on well-defined PtRu/Ru(0001) surface alloys and the modification of the adsorption properties of both adsorbate species due to coadsorption was studied by a combination of temperature-programmed desorption and infrared spectroscopic measurements. The hydrogen binding strength is weakened both by surface alloy formation and by CO coadsorption. In the densely packed coadsorbate layers, which can be formed after CO post-adsorption, the adsorption properties of the adsorbed CO molecules are also affected significantly. Depending on the Pt surface concentration, the CO adsorption process on hydrogen pre-covered surfaces is blocked to a different extent with a decreasing blocking tendency for Pt-rich alloys.
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Four approaches have been explored for the preparation of maleimido-functionalized self-assembled monolayers (SAMs) on silicon. SAMs prepared by self-assembly of maleimido-functionalized alkyltrichlorosilanes... more
Four approaches have been explored for the preparation of maleimido-functionalized self-assembled monolayers (SAMs) on silicon. SAMs prepared by self-assembly of maleimido-functionalized alkyltrichlorosilanes (11-maleimido-undecyl-trichlorosilane) on oxide-covered silicon yield higher signals from maleimido functionalities in ATR-IR (attenuated total reflection IR) spectroscopy and XPS (X-ray photoelectron spectroscopy) than the other three methods. The surface composition of maleimido groups was tailored further by the formation of mixed monolayers with nonfunctionalized alkyltrichlorosilanes (decyltrichlorosilane). The order of the alkyl chains within the monolayers only slightly depends on the composition of the mixed monolayers. We utilized the maleimido-terminated SAMs to bind various nucleophilic compounds, alkylamines, alkylthiols, and thiol-tagged DNA oligonucleotides by means of conjugate addition.
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Research Interests: Biomaterials, Stem Cells, Fluorescence Microscopy, Cell Migration, Cell Adhesion, and 15 moreStem Cell, Multidisciplinary, Neural stem cell, Humans, Surface modification, Micropatterning, Surface plasmon resonance, Neurons, Surface Properties, Microcontact Printing, Cell Proliferation, Somatic Cell Count, Umbilical Cord, Hydrogen-Ion Concentration, and Polyethylene Glycols
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Physicochemical Characterization 2nd Edition Exposure, Toxicology, and Impact on Human Health Chapter: 2. Physicochemical Characterization - Kirsten Rasmussen, Hubert Rauscher and Agnieszka Mech Editors: Bengt Fadeel, Antonio Pietroiusti,... more
Physicochemical Characterization 2nd Edition Exposure, Toxicology, and Impact on Human Health Chapter: 2. Physicochemical Characterization - Kirsten Rasmussen, Hubert Rauscher and Agnieszka Mech Editors: Bengt Fadeel, Antonio Pietroiusti, Anna Shvedova Hardcover ISBN: 9780128091999 eBook ISBN: 9780128094907 Publication date 16 March 2017