Theoretical potentiodynamic current/potential curves for a film formation process under an ohmic resistance control are given. Results are compared with experimental data involving the formation of insoluble parathiocyanogen on platinum and the precipitation of a solid CuCl layer during copper dissolution in aqueous-HCl

The human eye, the highly specialized organ of vision, is greatly influenced by oxidants of endogenous and exogenous origin. Oxidative stress affects all structures of the human eye with special emphasis on the ocular surface, the lens, the retina and its retinal pigment epithelium, which are considered natural barriers of antioxidant protection, contributing to the onset and/or progression of eye diseases. These ocular structures contain a complex antioxidant defense system slightly different along the eye depending on cell tissue. In addition to widely studied enzymatic antioxidants, including superoxide dismutase, glutathione peroxidase, catalase, peroxiredoxins and selenoproteins, inter alia, metallothioneins (MTs) are considered antioxidant proteins of growing interest with further cell-mediated functions. This family of cysteine rich and low molecular mass proteins captures and neutralizes free radicals in a redox-dependent mechanism involving zinc binding and release. The state of the art of MTs, including the isoforms classification, the main functions described to date, the Zn-MT redox cycle as antioxidant defense system, and the antioxidant activity of Zn-MTs in the ocular surface, lens, retina and its retinal pigment epithelium, dependent on the number of occupied zinc-binding sites, will be comprehensively reviewed.

Simultaneous determination of proteins with micrometric resolution is a significant challenge. In this study, laser ablation (LA) inductively coupled plasma -mass spectrometry (ICP-MS) was employed to quantify the distribution of proteins associated to the eye disease age-related macular degeneration (AMD) using antibodies labelled with three different metal nanoclusters (MNCs). PtNCs, AuNCs and AgNCs contain hundreds of metal atoms and were used to detect metallothionein 1/2 (MT1/2), complement factor H (CFH) and amyloid precursor protein (APP) in retina, ciliary body, retinal pigment epithelium (RPE), choroid and sclera from human cadaveric eye sections. First, the labelling of MNCs bioconjugated primary antibodies (Ab) was optimised following an immunolabelling protocol to avoid the non-specific interaction of MNCs with the tissue.Then, the LA and ICP-MS conditions were studied to obtain high-resolution images for the simultaneous detection of the three labels at the same tissue section. A significant signal amplification was found when using AuNCs, AgNCs and PtNCs labelled Ab of 310, 723 and 1194 respectively. After the characterisation of MNCs labelled immunoprobes, the antibody labelling was used for quantitative determination of MT1/2, CFH and APP in the RPE-choroid-sclera, where accumulation of extracellular deposits related to AMD was observed, suggesting that this method is fully suitable for the simultaneous detection and quantification of at least three different proteins.

No abstract

cost. The 40 ml min−1 optimum gas flow rate found for the proposed system is of the same order, and even compares Paper 8/01608I favourably, as those reported for better established selective

The electrode kinetics of the SCN-/(SCN), system has been studied on platinum in the temperature range from -12 to -3°C at different ammonium thiocyanate concentrations in aceto-n&rile in the presence of O-1 M [(C,H,),N]ClO,. Quasi-steady E/I curves with a Pt rotating disk electrode and EJI cufves at different linear potential-sweep rates were recorded under different experimental conditions. Both reactions of the pseudohalogen electrode are rather slow processes, the kinetics of which can be explained with the same mechanistic formalism postulated for the halogen electrodes in acetonitrile. R&u&-Etude de la clnetique &ctrochimique du systbme SCN-/(SCN),, sur electrode de platine, dans un domaine de temperatures de -12 & -3°C. pour differentes concentrations en thiocyanate d'ammonium dans l'ac&onitrile, en presence de [(CIH6),N]C10, 0,l M. Courbes quasi-stationnalres E/l sur electrode a disque de platine tournant et courbes E/I a differentes vitesses linkaims de balayage de potentiel, dans des conditions exp&imentales vari&s. Les deux reactions de I'blectrode a pseudo-halogene correspondent a des processus plutot lents, leurs cinetiques peuvent s'expliquer selon le m&canisme prtidemment post& pour les electrodes & halogkne dans l'ac&onitrile. Zusammenfassung-Es wurde die Elektroden-Kinetik des SCN-/(SCN),-Systems an Platinelektroden im Temperaturbereich von -12 bis -3°C unter Anwendung verschiedener Thiocyanatkonzentrationen in Acetonitrll in Gegenwart von 0,l M [(C,H6)4NIC10, untersucht. Unter verschiedenen experimentellen Bedingungen wurden quaslstationiire E/Z-Kurven an einer rotierenden Platinscheibenelektrode und E/Z-Kurven bei verschiedenen linearen Potentialschwenkgeschwindigkeiten aufgenommen. Beide Reaktionen der Pseudo-Halogenelektrode sind zlemlich langsame Prozesse, deren Kinetlk mlt dem gleichen Mechanlsmus erkhlrt werden kann, wle er fiir die Halogen-Elektroden in Acetonitril formuliert wurde.

Glaucoma is a multifactorial eye disease, characterized by progressive optic neurodegeneration. Elevation of the intraocular pressure is the main risk factor for glaucoma and is a consequence of an imbalance in the aqueous humor hydrodynamics, the physiology of which is influenced by the homeostatic equilibrium of essential elements, oxidative stress, and antioxidants. The aim of this work was to study local alterations in glaucomatous patients from two different, but connected, points of view: (i) the total antioxidant capacity (as an indicator of oxidative damage) and (ii) the concentration of mineral elements and their isotopic composition. Such objective was pursued using aqueous humor from patients diagnosed with pseudoexfoliation glaucoma (PEXG, n = 17) and primary open-angle glaucoma (POAG, n = 5) and age-matched control subjects (n = 16). The total antioxidant capacity (TAC) was examined in both aqueous humor and 60 serum samples (n = 20 controls, n = 20 for PEXG, and n = 20 for POAG), both showing higher TAC for the glaucoma population. The concentrations of the essential mineral elements (Cu, Fe, Mg, Na, P, and Zn) and the isotopic compositions of Cu and Zn were determined in aqueous humor using single-collector and multi-collector inductively coupled plasma–mass spectrometry, respectively. Significant differences were established for Mg and P levels when comparing the results for glaucomatous patients with those for the control population (p < 0.01 and p < 0.05 for Mg and P respectively, ANOVA and Kruskal-Wallis). The Zn isotopic composition was significantly shifted from that for the control population for PEXG patients. A significant difference in the isotopic composition of Zn was also established between the PEXG and POAG glaucoma cohorts. Graphical abstract

A new gas-sampling glow discharge (GSGD) is evaluated for the continuous determination of C, F, Cl, and S in molecular gases and organic vapors by optical emission spectrometry, with the use of helium as the discharge gas. Discrete aliquots of the sample are introduced into an exponential dilutor and carried by the support gas through a silica capillary tube and into the glow discharge. Radiation from the plasma source is viewed axially. The effects of plasma operating parameters such as power and pressure are studied, and emission lines of C, F, Cl, and S measured. Analytical performance is evaluated under conditions found to be optimal for each element, as well as under compromise conditions chosen for the simultaneous detection of all four elements. In both cases, detection limits in the low ng/s range, good precision (RSD < 5%), and dynamic ranges of 2–3 decades were observed for the four elements. The utility of this He–GSGD for the determination of elemental ratios in organic compounds is also investigated.