Hydrogen production from methanol by oxidative steam reforming carried out in a membrane reactor

The aim of this work is to study from an experimental point of view the oxidative steam reforming of methanol by investigating the behaviour of a dense Pd/Ag membrane reactor (MR) in terms of methanol conversion as well as hydrogen production. The main parameters considered are the operating temperature and the O₂/CH₃OH feed ratio. This is a pioneer work in the application of MR to this kind of reaction, whose goal should be to produce a CO-free hydrogen stream suitable for hydrogen fuel cell applications. The experimental results show that the MR gives methanol conversions higher than traditional reactors (TRs) at each temperature investigated, confirming the good potential of the membrane reactor device for this interesting reaction system.     

Modelling a hydropower plant with reservoir with the micropower optimisation model (HOMER)

Hydropower with water accumulation is an interesting option to consider in hybrid systems, because it helps dealing with the intermittence characteristics of renewable energy resources. The software HOMER (version Legacy) is extensively used in research works related to these systems, but it does not include a specific option for modelling hydro with reservoir. This paper describes a method for modelling a hydropower plant with reservoir with HOMER by adapting an existing procedure used for modelling pumped storage. An example with two scenarios in southern Brazil is presented for illustrating and validating the method explained in this paper. The results validate the method by showing a direct correspondence between an equivalent battery and the reservoir. The refill of the reservoir, its power output as a function of the flow rate and installed hydropower capacity are effectively simulated, indicating an adequate representation of a hydropower plant with reservoir is possible with HOMER.     

Study of spray drying of the Aloe vera mucilage (Aloe vera barbadensis Miller) as a function of its rheological properties

Spray Drying (SD) was used to obtain Aloe vera powder from fresh plants. The powder was reconstituted in an aqueous medium and its rheological properties, particle size distribution (PSD), thermal properties (differential scanning calorimetry, DSC), and morphology (scanning electron microscopy, SEM) were evaluated in order to find an alternative to natural gum to be used in the food industry. Rheological measurements were conducted at 25 °C in aqueous concentrations of 3 g/100 mL and 6 g/100 mL. A 2³ factorial design was used with three central points to evaluate yield, efficiency and the rheological properties of reconstituted powders, results were compared with a liophilized (FD) sample of A. vera mucilage. Experimental results showed that the shear viscosity decreased with the increase of the inlet air temperature and the speed of atomization, and it increased with increasing feed flow in SD. Additionally, most powders obtained in all treatments have an average particle diameter of ∼10 μm with a modal distribution (PSD). The best conditions of SD in order to obtain a good thickening agent were: 150 °C inlet temperature, 1.5 L/h feed rate and atomization speed of 275,000 rpm, and with rheological properties very close to those of the FD sample.     

Characterization of Mediterranean mussels (Mytilus galloprovincialis) harvested in Adriatic Sea (Italy)

The aim of this work was to analyse some quality parameters of Mytilus galloprovicialis harvested monthly in the period ranging from April 2002 and February 2003 in a longline off-shore mussel farm, located in the Adriatic Sea, near Cattolica (Emilia Romagna Region, Italy). After harvesting, the samples were analysed in order to determine the counts of fecal coliforms (FC) and Escherichia coli, the presence of Salmonella, as prescribed by Italian and European Community regulations, and other pathogens (Vibrio parahaemolyticus, Listeria monocytogenes), as well as the meat yield and its proximate composition, its Fe, Cr, Cd, Zn, Pb and Cu content, the total lipids of the meat and their specific composition. The results obtained evidenced that many of the parameters studied, i.e. the meat proximate composition, the lipid fatty acid composition and the microbiological indices, were subjected to seasonal fluctuations. In particular, the microbiological data showed that 4 mussel samples (June, December, January and February) out of 12 did not match the limit imposed by Italian law and Emilia Romagna protocol concerning the FC and E. coli counts. While L. monocytogenes and Salmonella spp. were never detected in all the samples analysed, three samples (April, January and February) were positive for the presence of V. parahaemolyticus. No seasonal fluctuations were evidenced for Fe, Cr, Cd, Zn, Pb and Cu contents, always under the limits imposed by Italian law.     

Digital library information-technology infrastructures

This paper charts a research agenda on systems-oriented issues in digital libraries. It focuses on the most central and generic system issues, including system architecture, user-level functionality, and the overall operational environment. With respect to user-level functionality, in particular, it abstracts the overall information lifecycle in digital libraries to five major stages and identifies key research problems that require solution in each stage. Finally, it recommends an explicit set of activities that would help achieve the research goals outlined and identifies several dimensions along which progress of the digital library field can be evaluated.     

On the use of double-skinned membranes to prevent chemical interaction between membranes and catalysts

This communication summarizes the use of double-skinned membranes for hydrogen separation in presence of TiO₂ based catalyst (PtReCe/TiO₂). The use of this type of membrane avoids the direct contact between catalyst particles and surface of the Pd-based hydrogen selective layer due to the presence of a mesoporous YSZ/γ-Al₂O₃ layer. The PdAg layer is protected by the mesoporous layer from direct contact with catalyst particles, avoiding erosion and possible chemical interactions. In comparison with a conventional PdAg membrane, the hydrogen flux of DS-membrane was observed not to be compromised during test carried out at 400 °C.     

A comparative assessment of thin-film photovoltaic production processes using the ELECTRE III method

The use of renewable energy sources for the production of electric power brings huge benefits both in terms of environmental protection as well as savings in non-renewable resources. Photovoltaic stands out from other renewable energy sources for its simplicity and the modularity of its energy conversion system. To date, the most highly developed technology for the construction of solar cells is one based on mono and polycrystalline silicon. An alternative production line is currently under development to produce, thin-film modules. There are currently a variety of processes and materials available to make thin-film cells but their relative costs and performance differ. Therefore, it would be useful to make a comparative evaluation of the different processes using a multiple criteria method.     

P-selectin, E-selectin, and CD40L over time in chronic hemodialysis patients

The aim of this study was to measure P-selectin, E-selectin, and CD-4L levels over time in chronic hemodialysis (HD) patients. Thirty stable patients with end-stage renal failure undergoing chronic HD were included in the study. Blood samples were obtained before HD for measurement of P-selectin, E-selectin, and CD-40L. Measurements were performed at month 0 (T0), 3 (T2), 8 (T3), and 13 (T4). The levels of P-selectin, E-selectin, and CD40L were also analyzed according to the occurrence of cardiovascular disease (CVD) and to CVD-related mortality. The levels of CD40L and P-selectin changed significantly over time, decreasing at month 3 and 6 and returning at the T0 levels at month 13. Conversely, E-selectin levels did not. The levels of CD40L, P-selectin and E-selectin over time did not differ significantly between patients with age ≤ 65 or > 65 years, between patients with or without CVD, or between patients who died or who survived during the follow-up. In end-stage renal failure patients undergoing chronic HD, CD40L and P-selectin, but not E-selectin, showed a transient decrease over time, and the serum levels of these molecules were not associated with CVD or with CVD-related mortality.     

Convergence for a family of discrete advection–reaction operators

We define a family of discrete Advection–reaction operators, denoted by $A_{a\lambda }$, which associate to a given scalar sequence $s=\left\{s_n\right\}$ the sequence given by $A_{a\lambda }\left(s\right)\equiv \left\{b_n\right\}$, where $b_n=a_{n?2}{s}_{n?1}+{\lambda }_n{s}_n$ for $n=1,2,\dots$. For $A_{a\lambda }$ we explicitly find their iterates and study their convergence properties. Finally, we show the relationship between the family of discrete operators with the continuous one dimensional advection–reaction equation.