Numerical simulation of hydrogen production by chemical looping reforming in a dual interconnected fluidized bed reactor

Although exploitation of dual interconnected fluidized bed systems (DIFB) is currently being explored in various fields (1,2), DIFBs present some criticalities, mainly related to effective control of solids recirculation and to avoidance of gas leakage between the beds, extremely critical in chemical looping reforming (CLR) for hydrogen production. For the latter, the choice of the degree of oxygen carrier oxidation/reduction, operation temperature and loop design makes the design even more challenging. This paper aims at quantitative assessment of the influence of design variables by means of the numerical simulation of a DIFB-CLR process operated at steady state. The model couples a simple hydrodynamic simulation of a DIFB system equipped with non-mechanical valves for bed solids circulation with a 1D, dynamic and non-isothermal CLR model developed to determine temperature and oxidation degree of solids and gaseous species concentrations at the exit of both air and fuel reactors. The DIFB (Fig. 1), consisting of a riser and of a bubbling fluidized bed (BFB) as air and fuel reactors respectively, was modelled as a combination of interconnected blocks (riser, cyclone, downcomers, L-valve, BFB, loop-seal) after selection of constitutive equations. Methane and Nickel(II) oxide were selected as fuel and oxygen carrier. Results corresponding to steady operation are presented and the effects on the expected process performance of operating conditions are assessed. It is concluded that an appropriate choice of both operating temperature and oxidation/reduction degree of oxygen carrier is an essential prerequisite in order to achieve auto-thermal regimes while assuring process feasibility and good performances in terms of CH4 conversion and H2 selectivity. Please click Additional Files below to see the full abstract

Chemical composition and protective effect of oregano (Origanum heracleoticum L.) ethanolic extract on oxidative damage and on inhibition of NO in LPS-stimulated RAW 264.7 macrophages.

The present study shows the chemical profile and the in vitro properties (antioxidant and inhibition of nitric oxide production) of the Origanum heracleoticum L. (Lamiaceae). The ethanolic extract of the aerial parts is characterized by terpenes and fatty acids. The extract, with high total phenol and flavonoid content, showed a significant radical-scavenging activity (IC(50) value of 12.8 μg/mL) using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) test and an interesting antioxidant activity with the β-carotene bleaching test (IC(50) values of 12.9 and 14.1 μg/mL at 30 and 60 min of incubation, respectively). The test for the inhibition of NO production, performed using the murine monocytic macrophage RAW 264.7 cell line, showed that the extract had significant activity with an IC(50) value of 108.5 μg/mL. The cytotoxic effect of O. heracleoticum extract in presence of lipopolysaccharide (LPS) (1 μg/mL) was evaluated but found to be negligible

AN INVESTIGATION ON LOW-TEMPERATURE FLUIDIZED COMBUSTION OF LIQUID FUELS

ABSTRACT Presently, the combustion at low temperature is receiving a great deal of interest because emissions of micro-and nanopollutants are expected to be greatly reduced. Following previous studies on the low temperature combustion behavior, the authors report results and discussion of steady-state experiments on an atmospheric, pre-pilot scale, 140 mm ID, FB reactor, equipped with an under-bed, airassisted, liquid-fuel injector. The experimental program was focused on the operation at temperatures lower than the classical value for FBC of solid fuels (i.e., 850°C). The data series taken into consideration are the concentrations of the main unburned species in the splash zone, those of oxygen measured in the bed and in the splash zone as well as the freeboard pressure. The interpretation of the results is mainly based on the statistical analysis in the time domain. The combustion pattern of bio-diesel is compared to that of the diesel fuel under varying operating conditions (e.g., bed temperature, dispersion air velocity at the fuel nozzle, injector height in the bed). Conclusions that were previously published on the base of labscale results are checked against new data obtained on the pilot scale. An innovative technique for the analysis of the micro-explosive regime is presented. It consists in the comparison of oxygen concentration measured by the zirconia-based probes at different heights in the bed and in the splash region, pressure signals measured in the freeboard and purposely filtered, and video-recordings of the bed surface phenomena. INTRODUCTION From a viewpoint directed at application of fluidized bed combustion (FBC), conventional, petroleum-derived liquid fuels are usually not taken into consideration. Vice versa, the cheap biomass-derived liquid fuels are worth of being exploited, at least for some specific applications. The combustion at low temperature is presently receiving a great deal of interest in view of depressing emission of micro-and nano-pollutants. The operation of a fluidized bed combustor (FBC) at a temperature lower than the classical value for FBC of solid fuels (i.e., 850°C) presents a number of interesting issues the mechanisms of which are not completely revealed yet. The combustion of a liquid fuel in a fluidized bed can be considered as the result of a number of serial stages: atomization, vaporization, pyrolysis, mixing with air and oxidation, formation of pollutant. They occur in an ideal sequence moving from the fuel inlet port to the bed exit, provided that the residence time in the bed is long enough [2] at the laboratory scale, i.e., with an 80 mm ID fluidized combustor. They identified a combustion behavior at a bed temperature below 750°C that was described as "regime with micro-explosions". Because of the periodic eruption of air bubbles the properties of th

Automated conduction velocity estimation based on isochronal activation of heart chambers

Background Spatial differences in conduction velocity (CV) are critical for cardiac arrhythmias induction. We propose a method for an automated CV calculation to identify areas of slower conduction during cardiac arrhythmias and sinus rhythm.Methods Color-coded representations of the isochronal activation map using data coming from the RHYTHMIA (TM) Mapping System were reproduced by applying a temporal isochronal window at 20 ms. Geodesic distances of the 3D mesh were calculated using an algorithm selecting the minimum distance pathway (MDP). The CV estimation was performed considering points on the boundary of two spatially and temporally adjacent isochrones. For each of the boundary points of a given isochrone, the nearest boundary point of the consecutive isochrone was chosen, the MDP was evaluated, and a map of CV was created. The proposed method has been applied to a population of 29 patients.Results In all cases of perimitral atrial flutter (16 pts out of 29 (55%)), areas with significantly low CV (< 30 cm/s) were found. Half of the cases present regions with low CV located in the anterior wall. No case with low CV at the so-called LA isthmus was observed. Right atrial maps during common atrial flutters showed low CV areas mainly located in the inferior inter-atrial septum. No areas of low CV were observed in subjects without a history of atrial arrhythmia while pts affected by paroxysmal AF showed areas with a limited extension of low CV.Conclusions The proposed software for automated CV estimation allows the identification of low CV areas, potentially helping electrophysiologists to plan the ablation strategy

A Double-Blind, RCT Testing Beneficial Modulation of BDNF in Middle-Aged, Life Style-Stressed Subjects: A Clue to Brain Protection?

Introduction: The aim of this prospective study was to see whether LD-1227, a quality-controlled marine nutraceuticals shown to protect experimental stress-induced hyppocampal degeneration, could beneficially modulate BDNF, as measured in the serum, in otherwise healthy but work-stressed individuals. Materials and Methods: Forty-eight men and women between the ages of 38 and 62 reporting high-demanding work activity but with an overall positive attitude towards their personal life were recruited. Subjects were divided in two group (24 patients each) and blindly supplemented for 2 month with: a) LD-1227 400mg or b) placebo. A third group of healthy non-stressed subjects was used as well. Blood samples were taken before and after the supplementation period. Unstimulated saliva was collected and tested for amylase while serum levels were used to measure BDNF. State Trait Anxiety Inventory (STAI), Pittsburgh Sleep Quality Index (PSQI) and psychological wellbeing assessment (PSWB) were measured too. Patients with Val66Met functional polymorphism of BDNF excluded those given their reported association with an impaired release of BDNF. Results: Results showed that, as compared to healthy, nonstressed individuals, stressed ones has a trend decrease of BDNF and this was significantly increased by LD 12-1227 supplementation and the same inverse phenomenon occurred to salivary amylase (p<0.05). No change was noted in the PSQI score but, either STAI or PSWB tests scored better in LD-1227 supplemented subjects. Conclusion: The present data suggest that LD-1227 is beneficially affecting neuromodulation and related symptoms during common stressful life conditions and may have the potential as tools in a neuroprotective clinical strategy

Cardiac resynchronization therapy-defibrillator improves long-term survival compared with cardiac resynchronization therapy-pacemaker in patients with a class IA indication for cardiac resynchronization therapy: Data from the Contak Italian Registry

Aims In candidates for cardiac resynchronization therapy (CRT), the choice between pacemaker (CRT-P) and defibrillator (CRT-D) implantation is still debated. We compared the long-term prognosis of patients who received CRT-D or CRT-P according to class IA recommendations of the European Society of Cardiology (ESC) and who were enrolled in a multicentre prospective registry. Methods and results A total of 620 heart failure patients underwent successful implantation of a CRT device and were enrolled in the Contak Italian Registry. This analysis included 266 patients who received a CRT-D and 108 who received a CRT-P according to class IA ESC indications. Their survival status was verified after a median follow-up of 55 months. During follow-up, 73 CRT-D and 44 CRT-P patients died (rate 6.6 vs. 10.4%/year; log-rank test, P = 0.020). Patients receiving CRT-P were predominantly older, female, had no history of life-threatening ventricular arrhythmias, and more frequently presented non-ischaemic aetiology of heart failure, longer QRS durations, and worse renal function. However, the only independent predictor of death from any cause was the use of CRT-P (hazard ratio, 1.97; 95% confidence interval, 1.21–3.16; P = 0.007). Conclusion The implantation of CRT-D, rather than CRT-P, may be preferable in patients presenting with current class IA ESC indications for CRT. Indeed, CRT-D resulted in greater long-term survival and was independently associated with a better prognosis

Effect of lead design and pacing vector on electrical parameters of quadripolar coronary sinus leads: The RALLY-X4 study

Abstract Background Various lead designs have been developed to accommodate different coronary sinus anatomies. Our objectives were to compare electrical parameters of straight and spiral left ventricular leads, to evaluate capture thresholds and impedances using different pacing vectors, and to study evolution of thresholds over time. Methods The RALLY-X4 study enrolled patients implanted with a lead from the Acuity X4 family (Straight, Spiral Short or Spiral Long). Electrical parameters (including capture thresholds from all 17 vectors) were measured at baseline and follow-up. Results Data from 795 patients who were successfully implanted were analysed. Straight and spiral leads had similar proportions of patients with thresholds 80% of patients. Pacing vectors significantly affect electrical parameters, with higher thresholds in more proximal electrodes and lower thresholds with unipolar and extended bipolar configurations. Capture thresholds slightly decreased over a mean follow-up of one year. This article is protected by copyright. All rights reservedPeer reviewe