Performance characterization of a novel Fe-based sorbent for anaerobic gas desulfurization finalized to high temperature fuel cell applications

A novel sorbent (SCX) composed of mixed iron oxides and hydroxides was studied to assess its suitability for H₂S removal from biogas finalized to high temperature fuel cell systems. From an industrial point of view, the potential usage of this product would have a beneficial impact on operational costs, since it is less expensive than activated carbons. Moreover, it is a non-hazardous landfilled product with a reduced environmental impact and it can be easily regenerated.Sorbent SCX was tested in different operative conditions, evaluating the influence on sorption capacity of gas hourly space velocity (GHSV), gas composition (inlet H₂S concentration, gas matrix, humidity), reactor temperature and filter geometry. As main outcomes, the experimentation highlighted: i) a hyperbolic increase in adsorption capacity as GHSV decreased, ii) a parabolic performance enhancement with increasing temperature and iii) a negative effect of humidity.Moreover, a comparison with commercial activated carbons typically used for the same purpose (Cu–Cr or KOH–KI treated) was performed, identifying the optimal operative parameters to obtain higher H₂S sorption capacity for SCX sorbent. Specifically, SCX showed its potential in terms of H₂S removal for GHSV lower than 330 h^?1, values of particular interest for many practical applications. In this case, an improved removal capability is obtained with respect to the ones exhibited by the considered carbons. Moreover, quantitative evaluations provided for unitary installed power (1 kW_e fuel cell-based systems) highlighted the possibility to have more compact (volume reduction of about 50%) and cheaper (cost reduction up to six times) filters.     

Soap film analogy for anisotropically stretched membranes and cable nets

Analogical physical models are a preferred technique to intuitively grasp complex engineering problems. It is well-known that the equilibrium minimal-surface configuration of membranes under equibiaxial tension can be visually represented by the surface of a soap film under equivalent boundary conditions, but this analogy fails when the stress state is not uniform equibiaxial. We extend to this situation the analogy with soap films. The equilibrium state of an orthotropically tensioned membrane is found by geometrically stretching the shape of a soap film, in a precise manner depending upon the applied state of stress. The procedure is easily done by elaborating digital pictures. The method is mathematically justified under the kinematic hypotheses of small strains and large rotations, and further verified in a parametric design environment. It can also provide an insight into the equilibrium configuration of cable-nets, when the stresses in the warp and weft directions are considerably different. Furthermore, this visualization favors implementing transformable shapes for membranes or orthogonal cable nets, as a consequence of a modification of the ratio of the principal stress components.     

Predicting TV programme audience by using twitter based metrics

Multimedia Tools and Applications - The predictive capabilities of metrics based on Twitter data have been stressed in different fields: business, health, market, politics, etc. In specific cases,...     

Ferromagnetic resonance isolator based on a photonic crystal structure with terahertz vortices

Photonic Network Communications - A new terahertz isolator based on the ferromagnetic resonance effect is suggested and analyzed. A two-dimensional photonic crystal consisting of a square lattice...     

Cell Creeping and Controlled Migration by Magnetic Carbon Nanotubes

Carbon nanotubes (CNTs) are tubular nanostructures that exhibit magnetic properties due to the metal catalyst impurities entrapped at their extremities during fabrication. When mammalian cells are cultured in a CNT-containing medium, the nanotubes interact with the cells, as a result of which, on exposure to a magnetic field, they are able to move cells towards the magnetic source. In the present paper, we report on a model that describes the dynamics of this mammalian cell movement in a magnetic field consequent on CNT attachment. The model is based on Bell’s theory of unbinding dynamics of receptor-ligand bonds modified and validated by experimental data of the movement dynamics of mammalian cells cultured with nanotubes and exposed to a magnetic field, generated by a permanent magnet, in the vicinity of the cell culture wells. We demonstrate that when the applied magnetic force is below a critical value (about F _c ≈ 10⁻¹¹ N), the cell ‘creeps’ very slowly on the culture dish at a very low velocity (10–20 nm/s) but becomes detached from the substrate when this critical magnetic force is exceeded and then move towards the magnetic source.