Finite Element Analysis of Material Flow in Mechanical Clinching with Extensible Dies

An investigation of the material flow during the clinching process with extensible dies is carried out. Clinched joints were produced under different forming loads to evaluate the evolution of the joints’ profile experimentally. Tensile-shear tests were conducted to evaluate the influence of the forming load on mechanical strength of the clinched joint. Since the joints’ strength depends on the joints’ profile, which in turn depends on the punch-die cavity volume, an analysis of the forces acting on the extensible dies was carried out. A finite element model was developed and validated by comparing the predicted and measured material flow and quality criteria (e.g., neck thickness and undercut). Therefore, the FE model was utilized to analyze the evolution of contact forces acting on the die sectors during the joining process. Furthermore, the main causes of the asymmetry in the cross section of such joints have been studied. It turned out that the axial asymmetry due to material flow within the gap between consecutive die sectors increases with the punch force and the sheet thickness.     

Comparative assessment of genotoxicity of mineral water packed in polyethylene terephthalate (PET) and glass bottles

The potential migration of genotoxic compounds into mineral water stored in polyethylene terephthalate (PET) bottles was evaluated by an integrated chemical/biological approach using short-term toxicity/genotoxicity tests and chemical analysis. Six commercial brands of still and carbonated mineral water bottled in PET and in glass were stored at 40 °C for 10 days in a stove according to the standard EEC total migration test (82/711/EEC), or at room temperature in the dark. After treatment, the samples were analysed using gas-chromatography/mass spectrometry (GC/MS) to detect volatile and non-volatile compounds, the Microtox^® test to evaluate potential toxicity of the samples, and three mutagenicity tests - Tradescantia and Allium cepa micronucleus tests and the Comet assay on human leukocytes - to detect their genotoxic activity.GC/MS analysis did not detect phthalates or acetaldehyde in the water samples. The Microtox^® test found no toxic effects. Mutagenicity tests detected genotoxic properties of some samples in both PET and glass bottles. Statistical analyses showed a positive association between mineral content and mutagenicity (micronuclei in A. cepa and DNA damage in human leukocytes). No clear effect of treatment and PET bottle was found. These results suggest the absence of toxic compounds migrating from PET regardless of time and conditions of storage. In conclusion, bottle material and stove treatment were not associated with the genotoxic properties of the water; the genotoxic effects detected in bottled water may be related to the characteristics of the water (minerals and CO₂ content).     

And Yet it Moves! Microfluidics Without Channels and Troughs

A simple, versatile, rapid, and inexpensive procedure based on the immersion method is developed to fabricate chemical gradients on chemically activated Si/SiO₂ surfaces by a trichloro (1H,1H,2H,2H‐perfluorooctyl) silane self‐assembly monolayer (SAM). Contact angle measurements, atomic force microscopy, and X‐ray photoelectron spectroscopy data based on the intensity of the signals of C1s and F1s, which progressively increase, indicate that the surface is characterized by the presence of increasing amounts of the SAM along the gradient direction. Experimental conditions are optimized by maximizing the variation of the contact angle of water drops at the starting and the ending points of the gradient. The application of the chemical gradient to droplet motion is demonstrated. The results are rationalized by dissipative particle dynamics simulations that well match the observed contact angles and the velocities of the drops. The simulations also show that the intrinsic nature of the gradient affects the velocity of the motion.     

Safe operating conditions for semibatch processes involving consecutive reactions with autocatalytic behavior

When strongly exothermic chemical processes are dealt with, safe and productive operating conditions may be difficult to identify; particularly if the reaction scheme is complex and the desired product is an intermediate. In this work, a new procedure for building boundary and temperature diagrams is developed to account for arbitrary kinetic expressions and multiple reactions. Such a procedure has been validated by comparison with literature experimental data involving autocatalytic consecutive reactions.     

Palermo,a City in Transition: Saint Benedict 'The Moor' versus Saint Rosalia

This paper discusses responses of the city council in Palermo to trends in immigration, in the context of the long-term physical decline of the historic centre. The paper describes these trends, the role and needs of ethnic minorities and problems related to their living conditions in the historic centre. It goes on to assess whether the specific issue of planning and ethnic minorities can suggest new approaches to a wider re-analysis of planning practices.     

On the pin-bearing failure load of GFRP bolted laminates: An experimental analysis on the influence of bolt diameter

This paper presents results summary of an experimental investigation aimed at evaluating the influence of the bolt diameter on the bearing failure strength of glass fibre reinforced polymer (GFRP) bolted laminates with epoxy matrix, for different values of fibre-to-load inclination angle. In this study, three different types of laminates were tested: one of them is mono-directional while the other two are bi-directional, with two different stacking sequence. Reductions in the pin-bearing ultimate load was found to be linearly dependent on bolt diameter. A pin-bearing design formula is also proposed based on experimental results.     

Thermodynamics and kinetics of phase transformation in intercalation battery electrodes - phenomenological modeling

Thermodynamics and kinetics of phase transformation in intercalation battery electrodes are investigated by phenomenological models which include a mean-field lattice-gas thermodynamic model and a generalized Poisson-Nernst-Planck equation set based on linear irreversible thermodynamics. The application of modeling to a porous intercalation electrode leads to a hierarchical equivalent circuit with elements of explicit physical meanings. The equivalent circuit corresponding to the intercalation particle of planar, cylindrical and spherical symmetry is reduced to a diffusion equation with concentration dependent diffusivity. The numerical analysis of the diffusion equation suggests the front propagation behavior during phase transformation. The present treatment is also compared with the conventional moving boundary and phase field approaches.