CO-free hydrogen production by steam reforming of acetic acid carried out in a Pd–Ag membrane reactor: The effect of co-current and counter-current mode

In this experimental work, a dense tubular Pd–Ag membrane reactor is used for carrying out the acetic acid steam reforming reaction for producing a CO-free hydrogen stream. The influence of the different flow configurations, as well as the sweep factor and the reaction pressure is analysed. A Ni-based commercial catalyst was packed in the lumen side of the membrane reactor and the experimental tests were performed at a reaction temperature of 400 °C and at a H₂O/acetic acid feed molar ratio of 10/1. Results in terms of CO-free hydrogen recovery, hydrogen yield and products selectivities are proposed. Moreover, a comparison between the performances of the membrane reactor and a traditional reactor working at the same operative conditions is illustrated and discussed.     

Comparison Between the Effects of Hypergravity and Photomechanical Stress on Cells Producing ECM

In the body, connective tissues have a major function in sustaining mechanical stresses. On the other hand, mechanical forces are important factors for connective tissue homeostasis. Connective tissues dynamically interact with mechanical and gravitational stimuli, changing their mechanical properties through the continuous modification of their composition, and thus improving their function. In connective tissues, mechanical forces are major regulators of extracellular matrix turnover, strongly affecting the production of extracellular matrix proteins. On the contrary, unloading conditions, such as bed rest or space flight, have a negative effect on these tissues, with loss of mass and impairment of mechanical properties. Here we describe the effect of photomechanical stress, supplied by a pulsed Nd:YAG laser, on extracellular matrix production by fibroblasts and chondrocytes, and compare it with the effect produced by hypergravity conditions. Cell morphology and structure, extracellular matrix production, cell adhesion, cell energy metabolism have been studied in treated human fibroblasts and chondrocytes by using immunocytochemistry, fluorescence and autofluorescence microscopy. The results show that photomechanical stress induce cytoskeleton remodelling, redistribution of membrane integrins, increase in production of ECM molecules, changes in cell energy metabolism. The effects are similar to those observed in the same cells exposed to cyclic hypergravitational stress (10×g).     

An empirical correlation between print through values and magnetic characteristics of chromium dioxide powders

While the measurement of the magnetic pro perties of the powders could be accomplished routinely, using gram-amount of materials, the determination of the print through requires the preparation of a magnetic tape in standard conditions. This latter fact introduces severe constraints for what concerns the amount of the material used and the reproducibility of the preparation method also in that critical laboratory phase which is the development of new materials or the improvement of older ones. It has been therefore thoroughly investigated the possibility of correlating magnetic properties of the CrO2powders, such as the specific saturation magnetization (σs), the coer civity factor (Hr-Hc)/Hcpercent and the magne tization at low fields with the print through. It has been shown that a good correlation is observed when those magnetic parameters are displayed in a function of the type:P.T. = A [sigma_{s}/C.F. times M.R.] + Band even better with a function of the type:P.T. = A [(sigma_{s})^{a}/(C.F.)^{b} times (M.R.)^{c}] + Bwhere P.T. is the print through value of the magnetic tape, C.F. is the coercivity factor defined above, M.R. = magnetization at 40 Oe/ saturation magnetization and a, b and c are numerical constants which could be obtained with a computer optimization procedure.     

The water-binding reaction of the mercury-iodine thermochemical cycle ANL-4: precipitation of KHCO3 from a purely aqueous medium

Yields and compositions of the products of the reaction H₂O + NH₃ + CO₂ + KI → KHCO₃ + NH₄I in aqueous solution are reported for the temperature range from 300 to 354 K. The effects of using pure water as a solvent for the water-binding reaction of the mercury-iodine thermochemical cycle ANL-4 are discussed.     

Analysis of fat deterioration-comparison of some photometric tests

Eight photometric methods (e.g., measurement of the diene absorption, ferrous isothiocyanate test, thiobarbituric acid value test, anisidine value, Kries test) for analysis of the oxidative deterioration of fats were compared with respect to sensitivity against autoxidized methyl linoleate and methyl linolenate. The ferrous isothiocyanate test was found to be the most sensitive method followed by the measurement of diene absorption. For assessment of the specificity, highly autoxidized methyl linoleate was separated by column chromatography into the following classes of compounds: volatile carbonyl compounds, monohydroperoxides, and polar peroxides-1 and-2. The influence of each class of compounds on the results of the eight tests was determined.     

Length Preserving Multiresolution Editing of Curves

In this paper a method for multiresolution deformation of planar piecewise linear curves that preserves the curve length is presented. In a wavelet based multiresolution editing framework, the curve can be deformed at any level of resolution through its control points. Enforcing the length constraint is carried out in two steps. In a first step the multiresolution decomposition of the curve is used in order to approximate the initial curve length. In a second step the length constraint is satisfied exactly by iteratively smoothing the deformed curve. Wrinkle generation is an application the paper particularly focuses on. It is shown how the multiresolution definition of the curve allows to explicitly and intuitively control the scale of the generated wrinkles.     

Timed service contract automata

Innovations in Systems and Software Engineering - We equip a recently developed model for the specification of service contracts with real-time constraints. Service contracts offer a means to...     

Sequencing batch reactors (SBRs) for BioH2 production: Reactor operation criteria

The production of ultra-pure hydrogen through biological processes is a promising alternative to conventional processes, such as steam reforming, limited by thermodynamic constraints: in this framework, Sequential Batch Reactors (SBRs) allow a strict control of the reaction environment, so as to guide the metabolic pathway towards the production of the desired products. In this work we have formulated a model for the dynamics of an SBR applied to biohydrogen production through a hexose source conversion by anaerobic (Clostridia) fermentation. We aimed at providing a useful tool to control the reactor performance in terms of SBRs operating conditions: an incorrect choice of key operating parameters would lead to an unstable reaction system, which is likely to shift to low-productivity working points.