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Voltammetry of immobilized microparticles (VMP) has been used in this work for the quantitative determination of tin and lead particles in their binary alloys. Carbon paste electrodes, which contained small amounts of tin and lead or their mixtures, were used as working electrodes and square wave voltammograms of each electrode were recorded. Quantification was performed using optimum experimental conditions, obtained by an experimental design technique. The calibration was made by measuring the percentage peak height of each metal taking the sum of peak currents of the both metals as 100 %. The results were compared with quantitative results of X‐ray fluorescence (XRF) technique to evaluate the capability of VMP method in its quantitative determination of solid samples. 相似文献
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Capillary–based microcells, also known as microcapillary electrochemical droplet cells, have proved their capabilities in various electrochemical surface investigations in recent decades. Due to the large measured current density and the high limiting current, this technique provides high–resolution electrochemical responses. Current densities in the range from a few femto to pico Acm?2 to hundreds of Acm?2 can be measured using this technique. Various applications for microcapillary cells have been reported. Technical limitations, such as the Ohmic drop and changes in the composition of the measurement area near the tip of the microcapillary have also been considered by some researchers. The rapid increase in the application of microcells and the increase in the number of related reports published in the literature have paralleled recent attempts to develop and improve microcell setups, showing that this technique is already well established for electrochemical surface studies. 相似文献
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[structure: see text] General methods for the synthesis of novel bifunctional hemithioindigo (HT) compounds, e.g., omega-amino acid derivatives, are presented. The photochromic properties of the photoswitches have been characterized by UV-vis and (1)H NMR spectroscopy. 相似文献
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V. Costa K. Leyssens A. Adriaens N. Richard F. Scholz 《Journal of Solid State Electrochemistry》2010,14(3):449-451
The characterization of materials constituting cultural artefacts is a challenging step in their conservation, due to the
object’s uniqueness and the reduced number of conservation institutes able to supply non-destructive analysis. We propose
an alternative analytical tool, which combines accessibility (low cost and portable) and high sensitivity, based on electrochemical
linear sweep voltammetry (LSV) with paraffin impregnated graphite electrode (PIGE). To investigate the composition of “white
alloys” that certainly have been used as decoration on copper-based Roman fibulae, sampling was done very locally by gently
rubbing the selected areas with the PIGE. LSV results evidence the presence of silver, lead, and tin, supporting the argument
provided by typological analysis that these metals were used for decoration. 相似文献
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Karolien De Wael Sandra Van Vlierberghe Hans Buschop Peter Dubruel Bart Vekemans Etienne Schacht Laszlo Vincze Annemie Adriaens 《Surface and interface analysis : SIA》2009,41(5):389-393
The aim of the present paper is to characterize a cross‐linked horse heart cytochrome c (HHC) film on cysteamine‐modified gold electrodes. The HHC film was deposited using 1‐ethyl‐3‐(3‐dimethylaminopropyl)‐carbodiimide (EDC) as a coupling agent. Attenuated total reflection infrared (ATR‐IR) spectroscopic analyses were performed to characterize the newly formed surface on a qualitative and conformational level. The film thickness was measured using a noncontact optical surface profiler, while quantitative data and information on the heterogeneity of the film were obtained by means of synchrotron radiation X‐ray micro fluorescence (SR micro‐XRF). Results indicate that, in addition to electrochemical studies, spectroscopic analysis methods are essential to gain insight in the effect of immobilization strategies on protein conformations. The latter is of relevance in the development and optimization of biosensors. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Dirksen A Meijer EW Adriaens W Hackeng TM 《Chemical communications (Cambridge, England)》2006,(15):1667-1669
A strategy for the synthesis of multivalent peptide-based nonsymmetric dendrimers by native chemical ligation using poly(lysine) dendritic wedges as scaffolds is presented. 相似文献
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Matmour R De Cat I George SJ Adriaens W Leclère P Bomans PH Sommerdijk NA Gielen JC Christianen PC Heldens JT van Hest JC Löwik DW De Feyter S Meijer EW Schenning AP 《Journal of the American Chemical Society》2008,130(44):14576-14583
Two oligo(p-phenylenevinylene)-peptide hybrid amphiphiles have been synthesized using solid- and liquid-phase strategies. The amphiliphiles are composed of a pi-conjugated oligo(p-phenylenevinylene) trimer (OPV) which is coupled at either a glycinyl-alanyl-glycinyl-alanyl-glycine (GAGAG) silk-inspired beta-sheet or a glycinyl-alanyl-asparagyl-prolyl-asparagy-alanyl-alanyl-glycine (GANPNAAG) beta-turn forming oligopeptide sequence. The solid-phase strategy enables one to use longer peptides if strong acidic conditions are avoided, whereas the solution-phase coupling gives better yields. The study of the two-dimensional (2D) self-assembly of OPV-GAGAG by scanning tunneling microscopy (STM) at the submolecular level demonstrated the formation of bilayers in which the molecules are lying antiparallel in a beta-sheet conformation. In the case of OPV-GANPNAAG self-assembled monolayers could not be observed. Absorption, fluorescence, and circular dichroism studies showed that OPV-GAGAG and OPV-GANPNAAG are aggregated in a variety of organic solvents. In water cryogenic temperature transmission electron microscopy (cryo-TEM), atomic force microscopy (AFM), light scattering, and optical studies reveal that self-assembled nanofibers are formed in which the helical organization of the OPV segments is dictated by the peptide sequence. 相似文献
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Adriaens A Dowsett M Leyssens K Van Gasse B 《Analytical and bioanalytical chemistry》2007,387(3):861-868
Immersion of corroded copper artefacts in dilute sodium sesquicarbonate solution is a well-recognized stabilization technique—especially
in the conservation of objects recovered from marine environments and therefore saturated with chlorides. Here we describe
three linked experiments performed to investigate a variation on this treatment, involving the application of a low potential
to the artefact in order to drive the chloride extraction process. This includes a new spectroelectrochemical approach which
allows 2-D pseudorandom X-ray reflection diffraction patterns to be obtained without interrupting the reaction in solution.
Experiments were carried out on synthetically produced chloride layers on copper (nantokite and atacamite). We show that a
thick chloride layer is, in general, replaced by a thin cuprite layer through a mechanism which involves detachment of the
chloride crystallites from the surface prior to dissolution. 相似文献
10.
Van Ham R Van Vaeck L Adriaens A Adams F Hodges B Gianotto A Avci R Appelhans A Groenewold G 《Talanta》2006,69(1):91-96
The feasibility of static secondary ion mass spectrometry (S-SIMS) for the detection of molecule specific information from complex materials, such as natural clay and soil samples, has been investigated. Ion trap (IT), as well as triple quadrupole (TQ) instruments, have been used for mass analysis. Secondary ion images have been acquired using time-of-flight (TOF) S-SIMS. The generation of molecular adduct ions from thin and thick layers on the mineral substrates has been investigated using KBr as a simple model system. Results show that molecular adducts of KBr can be indeed detected from the spiked materials. However, the concentrations of the spiking solutions have to be significantly larger than expected from the surface area measured by gas adsorption techniques. In addition imaging analysis has evidenced that the detection of adduct ions in the mass spectra directly relates to the presence of local micro-crystallites. 相似文献