bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immobilization of GOD and HRP enzymes on nanostructured substrates
Authors: Curulli A. , Cusmà A. , Kaciulis S. , Padeletti G. , Pandolfi L. , Valentini F. , Viticoli M. 
Published: March 2006

AbstractThe study of the entrapment of glucose oxidase (GOD) and horseradish peroxidase (HRP) enzymes on different solid‐state substrates has been carried out. By using conventional methods, these enzymes have been immobilized on the following substrates: commercial Si wafers, thin films of nanostructured TiO2 and gold nanotubes grown on polycarbonate membranes. Surface chemical composition and morphology of the samples have been investigated by means of X‐ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Peak‐fitting analysis of the main XPS signals permitted identification of the fingerprints of GOD and HRP enzymes and comparison of their entrapment on different substrates. The highest amount of attached enzymes was registered on the nanostructured TiO2 films prepared by using the sol–gel technique. Moreover, the surface impurities, remaining on the samples after the immobilization of the phosphate buffer solution, were identified, and their removability by sample washing in deionized water was demonstrated. Copyright © 2006 John Wiley & Sons, Ltd.
The initial oxidation of zirconium—oxide‐film microstructure and growth mechanism
Authors: Jeurgens L. P. H. , Lyapin A. , Mittemeijer E. J. 
Published: March 2006

AbstractThe initial stage of thermal oxidation of bare Zr within the temperature range of 373–773 K at a pO2 of 2 × 10−6 Pa was investigated by combined application of angle‐resolved XPS (AR‐XPS) and in situ spectroscopic ellipsometry (SE). A model description of the oxide‐film growth kinetics was achieved adopting coupled currents of cations and electrons within a surface‐charge field. The model could be fitted very well to the experimental data, thereby yielding profound knowledge of the relation between the oxidation mechanism and the developing oxide‐film microstructure. Copyright © 2006 John Wiley & Sons, Ltd.
Optical properties of thin iron oxide films on steel
Authors: Goossens V. , Wielant J. , Van Gils S. , Finsy R. , Terryn H. 
Published: March 2006

AbstractSteel is used for many applications, yet little research has centred on the optical properties of steel and its oxides compared to low‐density materials such as aluminium and titanium.In this paper, the optical properties of iron oxides on interstitial free steel substrates are studied. The oxide layers were thermally grown under an oxygen atmosphere at 250 °C. Two iron oxide types were present, i.e. α‐Fe2O3 (hematite) and Fe3O4 (magnetite). The optical constants of the oxide layer are determined by visual spectroscopic ellipsometry (VISSE). VISSE allows a fast and non‐destructive determination of both layer thickness and optical constants. An optical model was constructed to allow for the extraction of the layer thickness from the ellipsometric data. From this model, the total reflection, and therefore also the colour of the sample were calculated. The model is a good predictor of the system's colour, which proves that the colour originates from both interference and absorption effects. Copyright © 2006 John Wiley & Sons, Ltd.
Structural, chemical and magnetic characterization of iron nitride thin films
Authors: Prieto P. , Palomares F. J. , Gonzalez J. M. , Pérez‐Casero R. , Sanz J. M. 
Published: March 2006

AbstractIron nitride thin films were deposited on Si (100) substrates at 150 °C using a dual ion beam sputtering system. The structure, chemical composition and magnetic properties of the films were studied as a function of the deposition conditions. The bombardment with N2+ ions during the deposition of Fe by sputtering enabled control of the nitrogen content in the films and the formation of different iron nitride phases with different magnetic properties.The chemical, electronic and structural characterization of the films were performed by Rutherford backscattering spectrometry (RBS), AES‐depth profiling, and X‐ray diffraction (XRD), whereas the magnetic behavior was studied using a vibrating sample magnetometer (VSM).The results show that the magnetic moment of the Fe atoms decreases and the coercivity of the films increases almost linearly as the nitrogen content in the films increases up to the formation of ζ‐Fe2N, which is not magnetic. Copyright © 2006 John Wiley & Sons, Ltd.
Modeling the XPS Si 2p core‐level intensities of silicon nanocrystals for determination of oxide shell thickness
Authors: Renault O. , Marlier R. , Barrett N. T. , Martinez E. , Baron T. , Gely M. , De Salvo B. 
Published: March 2006

AbstractWe have developed a simplified model of the core and oxide shell XPS intensities of 5‐nm diameter Si nanocrystals for determining the shell thickness. The model is based on a cylindrical shape of the nanocrystals that allows the use of Himpsel's model for planar Si oxidation, and takes into account different escape depths for photoelectrons emitted by the core and the shell. The experimental core/shell intensity ratio is obtained from high‐resolution XPS spectra recorded with synchrotron radiation (photon energy 320 eV). The resulting calculated shell thickness is found to vary over the 0.74–1.32 nm range in a consistent way, according to the surface treatment performed on the nanocrystals. Copyright © 2006 John Wiley & Sons, Ltd.
Post‐chromatographic TOF‐SIMS identification of diterpenes
Authors: Oriňák Andrej , Oriňáková Renáta , Arlinghaus Heinrich F. , Vering Guido , Hellweg Sebastian 
Published: March 2006

AbstractMixture of two diterpenes was separated by thin layer chromatography (TLC) on different substrates and then analysed with time‐of‐flight secondary ions mass spectrometry (TOF‐SIMS). Abietic (AA) and gibberellic acids (GA) were separated on three different chromatographic thin layers: monolithic silica chromatographic ultra‐thin layer (A), aluminium backplate modified silica gel thin layer (B) and commercially available Raman spectrometric thin layer (C). GA is more polar and is stronger retained near the start of layer while AA moves with mobile phase front (ethanol–water, 40:60, v/v). Primary detection with UV lamp was possible only for AA. TOF‐SIMS macroscans of chromatographic thin layer surfaces have been collected for most intensive positive or negative charged ions. The most applicable TOF‐SIMS analytical signal response was obtained from analytes separated on monolithic silica and aluminium backplate modified thin layer surface. Thin layer produced for on‐line Raman spectroscopy is only partially suitable for TOF‐SIMS analysis and this substrate does not support construction of negative ions macroscans. The suitability of the substrates for post‐chromatographic TOF‐SIMS analysis was found in order: Raman spectroscopy thin layers < monolithic silica < and aluminium backplate modified surface—for negative ion macroscans. For positive‐ion macroscans formation, the order is as follows: Raman spectroscopy layer < aluminium backplate modified surface < and monolithic silica. The results obtained from these analyses should be applied in future coupling of TOF‐SIMS with microcolumn high‐performance liquid chromatography (µHPLC), online. TOF‐SIMS was chosen for its outstanding capabilities in molecular surface analysis and surface imaging, in particular, of mono‐, di‐, seskviterpenes. Copyright © 2006 John Wiley & Sons, Ltd.
Surface characteristics of 2‐(diethylamino) ethyl methacrylate–2‐(dimethylamino) ethyl methacrylate diblock copolymer determined by inverse gas chromatography
Authors: Topaloğlu Yazıcı D. , Aşkın A. , Bütün V. 
Published: March 2006

AbstractThe surface characterization of a 2‐(diethylamino) ethyl methacrylate–2‐(dimethylamino) ethyl methacrylate diblock copolymer [DEA‐DMA] was carried out using inverse gas chromatography (IGC). The adsorption thermodynamic parameters (the standard enthalpy (ΔHo), entropy (ΔSo), and free energy of adsorption (ΔGo)), the dispersive component of the surface energy ($\gamma_{S}^{d}$), and the acid–base character of the surface of the block copolymer were estimated using the retention time of different nonpolar and polar probes at infinite dilution region. This block copolymer showed convenient values of dispersive surface energy as compared to conventional polymers. The specific free energy of adsorption (ΔGsp), the specific enthalpy of adsorption (ΔHsp), and the specific entropy of adsorption (ΔSsp) of polar probes on diblock copolymer were determined. The values of the ΔHspwere correlated with both the donor and the modified acceptor numbers of the probes to quantify the acidic KA and the basic KD parameters of the block copolymer surface. The values obtained for the KA and KD parameters indicated a basic character for the surface of the DEA‐DMA diblock copolymer. Copyright © 2006 John Wiley & Sons, Ltd.
Angular distribution of electrons backscattered elastically from silver
Authors: Tőkési K. , Varga D. 
Published: March 2006

AbstractThe angular distributions of electrons backscattered elastically from a polycrystalline silver sample are studied theoretically. The simulation is based on the Monte Carlo technique where both the elastic and inelastic scattering events are taken into account. We analyzed the effect of multiple electron scattering to the spectra of elastically backscattered electrons. Copyright © 2006 John Wiley & Sons, Ltd.
A work function study of ultrathin alumina formation on Cu‐9%Al(111) surface
Authors: Song Weijie , Yoshitake Michiko 
Published: March 2006

AbstractWe studied work function changes during oxidation of Cu‐9%Al(111) surfaces at 900 and 670 K as a function of oxygen exposure in situ using ultraviolet photoelectron spectroscopy and Kelvin probe. The results showed that work function first decreased by 0.51 eV after 256 L O2 exposure at 900 K, and then remained unchanged upon further oxygen uptake. The formation of the interfacial dipole layer was the main factor that determined work function and XPS binding energy shifts of Al2O3 energy levels at 900 K. The changes of work function and contact potential difference for amorphous Al2O3 formation at 670 K were similar to their trends at 900 K. The oxide over‐layer structure showed little influence on the work function of the Al2O3/Cu‐9%Al(111) system. Copyright © 2006 John Wiley & Sons, Ltd.
Interactions of reactive polypyrrole‐coated polystyrene latex particles with gold nanoparticles and silanized glass
Authors: Yip Yann , Benabderrahmane Sihem , Zhicai Ma , Bousalem Smain , Mangeney Claire , Chehimi Mohamed M. 
Published: March 2006

AbstractPolypyrrole‐coated polystyrene latex particles (400–1000 nm‐sized) bearing reactive amino, carboxylic acid and N‐succinimidyl ester groups (PS‐PPyNH2, PS‐PPyCOOH and PS‐PPyNSE, respectively) were prepared by the in situ copolymerization of pyrrole (Py) and the N‐functionalized pyrrole in the presence of PS particles.The PS‐PPy spheres have a core/shell structure resulting in the formation of hollow particles after selective extraction of PS. The PS‐PPyNSE particles were immobilized at pH 7.4 onto various silanized glass plates. Surface coverage decreased in the order mercaptosilane > aminosilane ≫ methylsilane. The PS‐PPyCOOH was effective in forming 2D hexagonal assemblies onto aminated glass at pH 7 but not at pH 5. The PS‐PPyNH2 spheres can be decorated with citrate‐stabilized gold nanoparticles via electrostatic interactions and transformed into Au‐decorated hollow PPyNH2 particles after selective extraction of PS. Finally, gold nanoparticles immobilized onto an aminated glass plate could serve as a conversion layer for the massive attachment of PS‐PPyNH2, resulting in a very rough conductive overlayer. Copyright © 2006 John Wiley & Sons, Ltd.
Investigation of the interface manipulation in SiC(100) on Si(100) with isovalent impurities
Authors: Pezoldt J. , Morales F. M. , Zgheib Ch. , Förster Ch. , Stauden Th. , Ecke G. , Wang Ch. , Masri P. 
Published: March 2006

AbstractSIMS and transmission electron microscopy studies revealed an improvement of the SiC/Si(100) heterostructure properties if isovalent atoms with larger atomic dimensions than Si and C were used to modify the interface. The Ge incorporation at the interface suppresses the outdiffusion of Si from the substrate to the surface of the growing SiC layer and, therefore, impedes surface and interface roughening as well as the formation of voids at the SiC/Si interface. SIMS measurements obtained revealed that Ge remains at SiC/Si interface independently of the predeposited amount on Si(100) substrates. Copyright © 2006 John Wiley & Sons, Ltd.
Pulsed r.f.‐glow‐discharge time‐of‐flight mass spectrometry for fast surface and interface analysis of conductive and non‐conductive materials
Authors: Hohl M. , Kanzari A. , Michler J. , Nelis T. , Fuhrer K. , Gonin M. 
Published: March 2006

AbstractGlow discharge (GD) is a highly specialised source that especially meets the requirements for accuracy, simplicity and speed for content depth profiling and bulk analysis in both optical emission (OES) and mass spectrometry (MS). The pulsed radio frequency GD source has the potential for both elemental and molecular analysis of conductive and non‐conductive materials. To exploit the information delivered by pulsed radio frequency (r.f.)‐GD sources, fast sampling is required, and is available only through time‐of‐flight mass spectrometry (ToF‐MS). Compared to optical glow discharge (GD‐OES) instrumentation, a GD‐ToF‐MS system shows much simpler spectra, lower background signals and lower detection limits. The presented new r.f.‐GD‐ToF‐MS system is a successful combination of a commercial high‐end glow discharge instrument and an extremely fast and high‐resolution time‐of‐flight mass spectrometer. This new instrument was applied to analyse conductive and non‐conductive materials like anodic thin films. We could resolve 2‐nm Cr makers in aluminium oxide layers and measure trace elements in ultra thin titanium oxide films. Furthermore, we show the potential of the pulsed mode to separate analyte species from elements originating from residual gas. Copyright © 2006 John Wiley & Sons, Ltd.
Electroless deposition study of silver into porous silicon
Authors: Fortas G. , Sam S. , Gabouze N. , Guerbous L. , Belaroussi Y. , Manseri A. 
Published: March 2006

AbstractIn the present work, immersion plating method was used to deposit silver (Ag) into a porous silicon (PS) layer. The properties of the deposited layers as a function of the concentration of the solution and deposition time were investigated by X‐ray diffraction (XRD), scanning electron microscopy (SEM), secondary ion mass spectrometry (SIMS) and photoluminescence (PL). The results show that immersion plating is an efficient method to deposit Ag into the PS. It was found that the Ag diffusion in the porous layer reaches a depth of about 0.6 µm. Furthermore, the Ag grain sizes were highly dependent on the concentration of the solution and the deposition time. Finally, the luminescence measurements indicate an efficient PL of the sample with Ag deposit. In addition, compared to the PS luminescence spectrum, a red shift of the PL peak wavelength is observed. Copyright © 2006 John Wiley & Sons, Ltd.
Cylindrical and ring‐shaped tubulin assemblies as metallization templates explored by FESEM/EDX and SFM
Authors: Habicht Wilhelm , Behrens Silke , Unger Eberhard , Dinjus Eckhard 
Published: March 2006

AbstractTubulin self‐assembles in vitro in highly ordered polymorphic protein structures such as tubules or rings, which can be further utilized as a template to control the deposition of metal nanoparticles or for continuous metal coatings. Template‐directed alignment of particles or a continuous coverage is provided by metal salt incubation followed by a subsequent reduction procedure. We exploited field emission scanning electron microscopy (FESEM) with different electron detectors (inlens‐SE, BSE, TE) for morphological characterization, and an EDX unit for elemental analysis. Scanning force microscopy (SFM) in tapping mode (TM) was applied to image structural peculiarities and to measure the height of the biomolecular assemblies. We address tip‐surface interactions, the influence of fixation and cantilever types. Copyright © 2006 John Wiley & Sons, Ltd.
Film formation and characterization of anodic oxides on titanium for biomedical applications
Authors: Jaeggi Christian , Kern Philippe , Michler Johann , Patscheider Joerg , Tharian Joy , Munnik Frans 
Published: March 2006

AbstractFor a better understanding of the oxide growth and final film properties upon anodization of titanium in sulfuric and phosphoric acid containing electrolytes, the electrochemical behavior as studied by a.c. impedance was correlated to microstructural analysis (TEM, Raman). Chemical depth profiling of the films was performed with glow discharge optical emission spectroscopy (GDOES), XPS and RBS. The fitted capacitances and resistances from a.c. impedance measurements were greatly influenced by the ongoing crystallization as well as by film porosity as a function of increasing anodization potential. GDOES revealed a small sulfur contamination (with its maximum before the oxide–metal interface) upon anodization in 1 M H2SO4 and a significant phosphorus content throughout the oxides for films grown in 1 M H3PO4, showing an accumulation at the surface. Small impurities of carbon in all films as well as an accumulation of hydrogen at/after the interface oxide–metal were also observed. Quantification of the hydrogen content by elastic recoil detection analysis (ERDA) indicated a peak concentration of 20–30 at%. Copyright © 2006 John Wiley & Sons, Ltd.
Rapid depth profiling of lead zirconate titanate (PZT) thin films by pulsed glow‐discharge optical emission spectroscopy
Authors: Schwaller P. , Aeberhard M. , Nelis T. , Fischer A. , Thapliyal R. , Michler J. 
Published: March 2006

AbstractLead zirconate titanate (PZT) thin films have a large application potential in microelectronic devices, memory applications and microelectromechanical systems. Reactive sputtering of a single metallic target in a pulsed DC mode is a promising approach for a fast and cost‐efficient deposition of thin PZT films on an industrial scale. However, for efficient optimization of the process parameters, it is necessary to have access to a rapid tool for chemical depth profiling. We will show in this paper that glow‐discharge optical emission spectroscopy (GD‐OES) is capable of yielding fast and reliable information about the PZT thin film composition. A novel pulsed mode of GD‐OES was applied to bulk PZT samples (for calibrations purposes) and to thin PZT coatings. The influence of different parameters on this pulsed mode will be discussed. Using pulsed GD‐OES we could successfully measure the composition of our PZT thin films and so optimize the deposition process. Copyright © 2006 John Wiley & Sons, Ltd.
First stages of growth of cerium oxide deposited on alumina and reduced titania surfaces
Authors: Mansilla C. , Yubero F. , Zier M. , Reiche R. , Oswald S. , Holgado J. P. , Espinós J. P. , González‐Elipe A. R. 
Published: March 2006

AbstractWe have studied the first nucleation steps and the chemical interactions of small amounts of cerium oxide deposited on two surfaces with different chemical nature, alumina and a partially reduced titania. Cerium oxide was deposited by electron bombardment of CeO2pellets in ultra‐high vacuum conditions. All experiments were donein situin order to avoid contamination related to exposure to air. The relative amounts of Ce3+and Ce4+species present at the successive deposition steps have been quantified. It is found that for initial steps of deposition, high amounts of Ce3+are stabilised at the CeOx/TiOxinterface, while an approximately even mixture of Ce3+and Ce4+species appear at the CeOx/Al2O3interface. Thicker deposits are characterised by the presence of only Ce4+species independently of the substrate. It is found that cerium oxide grows in the form of islands on both substrates. These islands are taller in the case of deposition on reduced titania than on alumina. This result is confirmed by both angle resolved X‐ray photoelectron spectroscopy (XPS) and inelastic XPS peak shape analysis. The correlation between the growing microstructure and the chemical interaction at the interfaces is discussed. Copyright © 2006 John Wiley & Sons, Ltd.
Measurement of the differential electron surface and volume excitation probability in Cu, CuO and Cu2O
Authors: Werner W. S. M. , Zemek J. , Jiricek P. 
Published: March 2006

AbstractReflection electron energy loss spectra (REELS) were measured for Cu and in situ‐grown Cu2O and CuO. The differential surface and volume inelastic excitation probability is extracted from the REELS using a rigorous procedure developed recently. The resulting surface and volume loss probabilities for Cu agree quantitatively with theoretical calculations based on optical data. The resulting loss distributions can be used for a rigorous line shape analysis of XPS and AES spectra of these materials. Copyright © 2006 John Wiley & Sons, Ltd.
Simple surface treatments to modify protein adsorption and cell attachment properties within a poly(dimethylsiloxane) micro‐bioreactor
Authors: Boxshall Keir , Wu Min‐Hsien , Cui Zheng , Cui Zhangfeng , Watts John F. , Baker Mark A. 
Published: March 2006

AbstractPoly(dimethylsiloxane) (PDMS) elastomers are widely used in biological laboratories to produce prototype micro‐bioreactors. The need was identified for a simple modification of the PDMS surface to prevent protein adsorption and cell attachment in certain areas and to increase the level of cell attachment where desirable. A study has been undertaken into the effect on protein adsorption and cell attachment of adsorbed surfactants and sodium hydroxide (NaOH) modification of the surface. The proteins are adsorbed from Dubecco's Modified Eagles Medium (DMEM) supplemented with foetal calf serum, HEPES, antibiotics, and ascorbic acid, as will be used to maintain the cells in the micro‐bioreactor. Protein adsorption has been quantified by X‐ray photoelectron spectroscopy (XPS) and the viable cell attachment by MTT assay. Protein and cell configuration were studied by atomic force microscopy (AFM) and light microscopy (LM) respectively. A positive correlation is observed between the level of protein adsorption and cell attachment. The Pluronic® F68 surfactant treatment exhibited the greatest reduction in protein adsorption and cell attachment, followed by the Pluronic® F127, with Tween™ 20 being the least effective. The NaOH treatment showed a substantial increase in both protein adsorption and cell attachment. Copyright © 2006 John Wiley & Sons, Ltd.