Mechanical squeezing of an elastomeric nanochannel device: numerical simulations and ionic current characterization

Peculiar transport phenomena appear at nanoscale, since surface effects strongly affect the behaviour of fluids. Electrostatic and steric interactions, capillary forces and entropic effects play a key role in the behaviour of fluids and biomolecules. Since these effects strongly depend on the size of the nanofluidic system, a careful characterization of the fluidic environment is necessary. Moreover, the possibility to dynamically modulate the size of nanochannels is very appealing in the field of biomolecule manipulation. Recently, we have developed a lab-on-chip made of poly(dimethylsiloxane) (PDMS). This polymeric device is based on a tuneable nanochannel able to dynamically change its dimension in order to fit the application of interest. In fact, a mechanical compression applied on the top of the elastomeric device squeezes the nanochannel, reducing the channel cross section and allowing a dynamical optimization of the nanostructures. In this paper, this squeezing process is fully characterized both numerically and experimentally. This analysis provides information on the reduction of the nanochannel dimensions induced by compression as a function of the work of adhesion and of the stiffness of the materials composing the device. Moreover, calculations demonstrate the possibility to predict the change of the nanochannel size and shape induced by the compression. The possibility to dynamically tune the channel size opens up new opportunities in biomolecular sensing or sieving and in the study of new hydrodynamics effects.     

FMS for Unmanned Aerial Systems: HMI Issues and New Interface Solutions

To integrate UASs in the NAS, an improvement in navigation, planning, communication and 4D trajectory control capabilities is mandatory. A way to obtain this enhance is to adopt a Flight Management System. A FMS for an UAS has some differences with respect to one for a manned aircraft, in terms of architecture and performed functions. In particular, from HMI point of view, the specific UAS human factor issues shall be added to the current manned FMS interface lacks. Starting from these considerations, a new FMS HMI for the Alenia Aeronautica TCS has been developed, using as data entry devices two touch screens.     

Validation of hot ring rolling industrial process 3D simulation

Ring rolling is a hot forming process used in the production of railway tyres, anti friction bearing races and different ring shaped work pieces for automotive energy production and aerospace applications. The advantages of ring rolling process include short production time, uniform quality, closed tolerances, good material quality and considerable saving in material cost. Despite the benefits some problems still exist according to a correct selection of the process parameters. Due to the nature of the process different rolling mills (driving, idle and axial rolls) are involved and the correct selection of the process parameters is not so feasible. Moreover an experimental approach to solve this problem risks to be more expensive. Actually FE codes are available to simulate the non linear problem that characterizes a ring rolling process. In this work a FE model, based on Deform 3D software, was tested versus experimental results acquired from an industrial plant. The accuracy of the FE model was analyzed through a dual comparison: by geometrical and by physical aspects. A good agreement was found between experimental and numerical results for both comparisons and, as a consequence, this code could be used in order to investigate and optimize the process parameters that characterize the ring rolling process in a virtual not expensive environment. The validated model will allow the studies of more environment-friend process configurations.     

Characterization of laser energy consumption in sintering of polymer based powders

This paper presents an analysis of Laser Sintering (LS) process from an energy standpoint. LS has a potential as an environmental benign alternative to traditional processes but only few authors deal with the process optimization including the energy aspects. This work evaluates the effect of the energy density in processing of two polymeric materials: polyamide powder and a phenolic resin coated sand. The different behaviour of the two materials is studied by analysing the geometrical features (depth and width) of linear sintered structures. In particular the volumetric productivity and the energy intensity of the process are calculated to characterize the sintering process.It is shown how an upper limit to the energy consumption can be remarked. Measurements reveal that within the energy density range of 0.02-0.1 J/mm² the whole energy input is useful for the agglomeration process. The use of higher energy density produces different results for both the cases analysed. A proper selection of energy density maintains the energy requirement below the level of 10⁶ J/kg which is considered a lower limit for manufacturing process.     

Optical and electrical characterization of a gold nanoparticle dispersion in a chiral liquid crystal matrix

We report on the effect of gold nanoparticle (Au NP) dispersion in a chiral nematic liquid crystal (LC). Polarized optical microscopy and X-ray diffraction measurements evidence the insurgence of an order change in the LC host. Moreover, a comparative analysis based on dielectric and voltammetric spectroscopies performed on pure LC and on Au NP-doped LC shows that Au NP’s presence besides affecting LC order influences its electric properties: ion conductivity results importantly reduced, and beyond a threshold value of the applied field electrophoresis phenomena are induced.