Evaluation of electrochemical surface pretreatment methods on the preparation of monomeric molybdate(VI)-modified glassy carbon electrode (GCE) in H2SO4 is studied. The results show that the cathodically treated GCE is unusually highly activated toward Mo(VI) adsorption, but the anodized electrode does not respond, unlike the previous reports for the other adsorbed systems. The analyses of the voltammograms of Mo(VI) on a cathodized electrode show three pairs of reversible peaks with a surface excess on the order of ≅1 × 10-10 mol cm-2 for each of the peaks. The interaction parameters for the three processes are 1.14 × 109, 1.38 × 109, and −5.50 × 109 cm2 mol-1, respectively. Strong interaction between the Mo(VI) ion and cathodically reduced GCE surface groups is indicated by the formation of Mo(V) (detected by x-ray photoelectron spectroscopy (XPS) and electrochemical polarization measurements) during the course of Mo(VI) adsorption at open circuit conditions. The Mo(VI) adsorption via the mixed potential mechanism has been formulated involving Mo(VI) reduction to Mo(V) coupled with surface alcohol group oxidation to hydroperoxide. XPS analyses show that the cathodized surface contains higher amounts of >C−O− surface groups. The quantities of >C−O− surface groups correlate with the observed differences in the response of the pretreated GCE surfaces toward Mo(VI) adsorption.

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We have studied the electrocatalytic activity of RuO2-PVC film electrodes, fabricated using RuO2 powders prepared at five different temperatures, viz., 300, 400, 500, 600 and 700 degrees C, for the oxidation of glucose in high alkaline media, 1 to 3 M NaOH. The RuO2-PVC film electrodes have been first characterized in 1 to 3 M NaOH solution by cyclic voltammetry (CV) and rotating disc electrode (RDE) techniques in a wide potential range -1,100 to 450 mV (SCE), and three redox pairs representing Ru(IV)/Ru(III), Ru(VI)/Ru(IV) and Ru(VII)/Ru(VI) transitions have been identified. The voltammetric peaks at low sweep rates have been analyzed using surface activity theory formulated for interacting electroactive adsorption sites, and interaction terms have been evaluated. The total voltammetric surface charges have been analyzed as per Trassatti's formalism with respect to their dependence on potential sweep rate, and charges associated with less accessible and more accessible surface sites have been calculated. For glucose oxidation, the results have indicated that RuO2 (700 degrees C)-PVC electrode shows two oxidation peaks in contrast to RuO2 (300 degrees C)-PVC electrode. Also, RuO2 (700 degrees C)-PVC electrode exhibits higher intrinsic electrocatalytic activity than the 300 degrees C electrode, although the former possesses lower electrochemically active surface area. Additionally, kinetic analyses made from RDE results with reference to Michealis-Menten (MM) enzyme catalysis has shown that RuO2 (700 degrees C) electrode possesses extended glucose-sensing range in terms of MM kinetic constant, K (M) , compared to other electrodes. Possible reasons for such differences in the behavior of the electrodes of different temperatures towards glucose oxidation are identified from studies on oxidation of glucose in solutions of different pH, oxidation of different glucose derivatives, and also from physicochemical results from BET, XRD, SEM, DTGA, XPS analysis of RuO2 powder samples

In general, organic capping molecules are applied to passivate the surface of semiconductor nanomaterials to modulate the optical properties of these nanostructures. In this work, two alkylamines (n-butylamine (n-BA) and n-hexylamine (n-HA)) and oleic acid (OA) were used to modify the surface of moderately high luminescent CdS quantum dots (QDs). From the photoluminescence (PL) spectra and the quantum yield (QY) analyses, we observed that the PL QY of the CdS QDs decreased after introduction of the alkylamine and oleic acid molecules. The PL decay kinetics for these CdS-capping molecule systems were followed by time-resolved photoluminescence (TRPL), and the spectra were analyzed in terms of a biexponential model identifying two lifetime values, shorter lifetime (τ S ) and longer lifetime (τ L ). Compared to bare CdS QDs, for the CdS QDs surface modified by alkylamine or fatty acid, both the shorter and the longer excited state lifetimes were decreased; the fractional contribution by the longer-lifetime component became reduced and the shorterlifetime component accounted for most of the total PL. Density function theory (DFT) simulation was employed using a Cd 3 S 5 cluster to model the adsorption of organics to calculate the binding energy and the charge on Cd and S of CdS. By comparing the elemental charges of the bare CdS with those of the CdS modified by the organic molecules, it is suggested that n-BA, n-HA, and OA could decrease the surface related radiative charge-recombination process and the PL-QY of the CdS QDs.

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Aims Sudden cardiac death (SCD) is the most common mode of death in paediatric hypertrophic cardiomyopathy (HCM). This study describes the implant and programming strategies with clinical outcomes following implantable cardioverter-defibrillator (ICD) insertion in a well-characterized national paediatric HCM cohort. Methods and results Data from 90 patients undergoing ICD insertion at a median age 13 (±3.5) for primary (n = 67, 74%) or secondary prevention (n = 23, 26%) were collected from a retrospective, longitudinal multi-centre cohort of children (<16 years) with HCM from the UK. Seventy-six (84%) had an endovascular system [14 (18%) dual coil], 3 (3%) epicardial, and 11 (12%) subcutaneous system. Defibrillation threshold (DFT) testing was performed at implant in 68 (76%). Inadequate DFT in four led to implant adjustment in three patients. Over a median follow-up of 54 months (interquartile range 28–111), 25 (28%) patients had 53 appropriate therapies [ICD shock n = 45, anti-tachycardia pacing (ATP) n = 8], incidence rate 4.7 per 100 patient years (95% CI 2.9–7.6). Eight inappropriate therapies occurred in 7 (8%) patients (ICD shock n = 4, ATP n = 4), incidence rate 1.1/100 patient years (95% CI 0.4–2.5). Three patients (3%) died following arrhythmic events, despite a functioning device. Other device complications were seen in 28 patients (31%), including lead-related complications (n = 15) and infection (n = 10). No clinical, device, or programming characteristics predicted time to inappropriate therapy or lead complication. Conclusion In a large national cohort of paediatric HCM patients with an ICD, device and programming strategies varied widely. No particular strategy was associated with inappropriate therapies, missed/delayed therapies, or lead complications.