Physical activity measured by implanted devices predicts atrial arrhythmias and patient outcome: Results of IMPLANTED (Italian Multicentre Observational Registry on Patients With Implantable Devices Remotely Monitored)

Background--To determine whether daily physical activity (PA), as measured by implanted devices (through accelerometer sensor), was related to the risk of developing atrial arrhythmias during long-term follow-up in a population of heart failure (HF) patients with an implantable cardioverter defibrillator (ICD). Methods and Results--The study population was divided into 2 equally sized groups (PA cutoff point: 3.5 h/d) according to their mean daily PA recorded by the device during the 30- to 60-day period post-ICD implantation. Propensity score matching was used to compare 2 equally sized cohorts with similar characteristics between lower and higher activity patients. The primary end point was time free from the first atrial high-rate episode (AHRE) of duration 656 minutes. Secondary end points were: first AHRE 656 hours, first AHRE 6548 hours, and a combined end point of death or HF hospitalization. Data from 770 patients (65\ub115 years; 66% men; left ventricular ejection fraction 35\ub112%) remotely monitored for a median of 25 months were analyzed. A PA =3.5 h/d was associated with a 38% relative reduction in the risk of AHRE 656 minutes (72-month cumulative survival: 75.0% versus 68.1%; log rank P=0.025), and with a reduction in the risk of AHRE 656 hours, AHRE 6548 hours, and the combined end point of death or HF hospitalization (all P < 0.05). Conclusions--In HF patients with ICD, a low level of daily PA was associated with a higher risk of atrial arrhythmias, regardless of the patients' baseline characteristics. In addition, a lower daily PA predicted death or HF hospitalization

Comparison between different ways to determine diffusion coefficient and by solving Fick’s equation for spherical coordinates

The following document covers the determina- tion of the diffusion coefficient of two powder materials: LiFePO4 and LiMn2O4 by using potentiostatic intermittent titration technique (PITT) and impedance spectroscopy methodology and compares relevant results with the following relation: D 1⁄4 R2 I0 , which is obtained by solving 3aQ Fick’s spherical coordinate equation (where I0 is the initial step current in the PITT experiment, R is the particle radius, Q is the charge that intercalated during the step, and α is the percentage of the theoretical intercalated charge). This procedure allowed the verification of the validity of the spherical model for the powder materials, the accuracy of the expression proposed for the diffusion coefficient determination, and the correctness of the measures that had been taken

Economical electrolyser solution

In the market there are conventional alkaline electrolysers and advanced polymer membrane electrolysers, with higher performance, but they are both quite expensive. Indeed, the materials commonly utilized for water electrolysis in alkaline electrolysers are those based on Raney nickel and their alloys, but these materials are expensive. Taking into account those aspects, the following work aims, as other authors [Olivares-Ramireza JM, Campos-Corneliob ML, Uribe Godinezb J, Borja-Arcob E, Castellanosb RH. Studies on the hydrogen evolution reaction on different stainless steels. Int J Hydrogen Energy 2007; 32: 3170-3. [1]; Henrique dos Santos Andrade M, Lima Aciolia M, Ginaldo da Silva juniora J, Carlos Pereira Silvaa J, Oliveira Vilarc E, Tonholoa J, Preliminary investigation of some commercial alloys for hydrogen evolution in alkaline water electrolysis. Int J Hydrogen Energy 2004;29:235-41. [2]], to highlight how it is possible to produce hydrogen in economical ways using less advanced technologies. A conventional alkaline electrolytic cell, "lab-electrolyses", has been built using economical material. It is composed of electrodes of 5.0 cm x 5.0 cm characterized by a current density of about 250 mA/cm(2) and an efficiency of about 65% at 55 degrees C; the cell produces about 2.7 Nl/h of hydrogen. The overall cost of this devise has been compared with the cost of the electrolysers available on the market, hypothesizing a linear dependence cost with the productive capacity. The conclusion has been that there is a big margin for costs decreasing even taking into account all the auxiliary systems for an electrolysis process. (c) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved

Produzione di idrogeno mediante foto-elettro-catalisi

l’energia solare, evitando il processo fotovoltaico ed elettrolitico ed usando la luce solare direttamente come fonte di energia per scindere l’acqua nei suoi costituenti elementari. Molto è stato fatto negli ultimi trenta anni per trovare un materiale adatto alla scomposizione dell’acqua per fotocatalisi in una cella elettrochimica. Un buon materiale per la fotocatalisi deve avere: un’appropriata differenza di energia tra le bande che sia ottimale per la scissione dell’acqua (approssimativamente 2 eV tra il bordo superiore della banda di conduzione e il bordo inferiore della banda di valenza tale da contenere il potenziale redox dell’acqua), un assorbimento ottico nelle regioni spettrali del visibili e dell’ultravioletto, una buona stabilità con le soluzioni elettrolitiche e un’efficiente proprietà di trasferimento di carica tra il semiconduttore e l'elettrolita. Il biossido di titanio è stato usato come fotocatalizzatore, esso non è tossico è stabile e poco costoso. Test preliminari hanno mostrato la formazione di idrogeno e misure di spettroscopia d’impedenza condotte in assenza e in presenza di luce hanno mostrato che la luce riduce la resistenza al trasferimento di carica nell’interfase elettrodo soluzione. Nella fase preliminare di studio abbiamo avuto rese basse ma l’utilizzo di alcuni additivi al semiconduttore hanno mostrato un miglioramento del processo

Renewable and hydrogen energy integrated house

The residential sector accounts for about a third of the total world energy consumption. Energy efficiency, Renewable Energy Sources and Hydrogen can play an important role in reducing the consumptions and the emissions and improving the energy security if integrated (Efficiency, Res, Hydrogen) systems are developed and experimented. The paper analyzes a real residential 100 square meters house, where energy efficiency measures and RES technologies have been applied, sizing a hydrogen system (electrolyzer, metal hydrides and fuel cell) for power backup, taking into consideration its dynamic behavior, experimentally determined. The technologies used are already available in the market and, except hydrogen technologies, sufficiently mature. Through energy efficiency technologies (insulation, absorbers, etc), the maximum electrical and thermal power needed decreases from 4.4 kW(e) to 1.7 kW(e) (annual consumption from 5000 kWh to 1200 kWh) and from 5.2 kW, to 1.6 kW(t) (annual consumption from 14,600 kWh to 4500 kWh) respectively. With these reduced values it has been possible to supply the consumptions entirely by small photovoltaic and solar thermal plants (less than 10 m(2) each). The hydrogen backup even if remains the most expensive (versus traditional batteries and gasoline generator), satisfying all the electric needs for one day, increases the security and allows net metering. Moreover the low-pressure hydrogen storage system through metal hydrides guarantees system safety too. Finally the system modularity can also satisfy higher energy production. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved

Nickel-cobalt electrodeposited alloys for hydrogen evolution in alkaline media

A study on the electrocatalytic Performances of nickel-cobalt alloys for hydrogen evolution in alkaline media has been carried out. After preparing, by electrodeposition on aluminium net supports, Ni-Co alloys of various compositions ranging from 0 to 100% Ni, the alloys were examined by polarization measurements, to evaluate their discharge potential and Tafel parameters. Moreover a durability test has been done on the alloys showing, among all, the best performance, The hydrogen over-potential appears to be lower in the case of Ni concentrations ranging between 35 and 59 weight percent. The synergism among the nickel catalytic properties, having low hydrogen over-potential and high hydrogen adsorption of cobalt, is best realized in this conditions and allow obtaining a largest value of exchange current density. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved