Nicola A. Nodargi

Numerical Investigation of a Novel Wiring Scheme Enabling Simple and Accurate Impedance Cytometry

Microfluidic impedance cytometry is a label-free approach for high-throughput analysis of particles and cells. It is based on the characterization of the dielectric properties of single particles as they flow through a microchannel with integrated electrodes. However, the measured signal depends not only on the intrinsic particle properties, but also on the particle trajectory through the measuring region, thus challenging the resolution and accuracy of the technique. In this work we show via simulation that this issue can be overcome without resorting to particle focusing, by means of a straightforward modification of the wiring scheme for the most typical and widely used microfluidic impedance chip.

Square Cross Vaults on Spreading Supports

This paper investigates the static of masonry square cross vaults on spreading supports through the limit analysis approach adopting a rigid no-tension constitutive model with no sliding. Compatible three-dimensional mechanisms are considered and a rigorous application of thrust line analysis is adopted, in order to evaluate vaulted structure capacity in terms of collapse displacement and associated thrust. For a better understanding of the behaviour of the square cross vault under large displacements, the related case of the elliptical arch on spreading supports is first analysed. The effect of the main geometric parameters and the different possible failure mechanisms are examined and discussed.

MICRO-SCALE TECHNOLOGIES FOR CELL MECHANICS: EXPERIMENTAL AND MODELLING APPROACHES

− Cell mechanics is a discipline that bridges cell biology with mechanics. Emerging microscale technologies are opening new venues in the field, due to their costeffectiveness, relatively easy fabrication, and high throughput. Two examples of those technologies are discussed here: microfluidic impedance cytometry and erythrocyte electrodeformation. The former is a lab-on-chip technology offering a simple, non-invasive, label-free method for counting, identifying and monitoring cellular biophysical and mechanical function at the single-cell level. The latter is a useful complement to the former, enabling cell deformation under the influence of an applied electric field.

An Overview of Mixed Finite Elements for the Analysis of Inelastic Bidimensional Structures

As inelastic structures are ubiquitous in many engineering fields, a central task in computational mechanics is to develop accurate, robust and efficient tools for their analysis. Motivated by the poor performances exhibited by standard displacement-based finite element formulations, attention is here focused on the use of mixed methods as approximation technique, within the small strain framework, for the mechanical problem of inelastic bidimensional structures. Despite a great flexibility characterizes mixed element formulations, several theoretical and numerical aspects have to be carefully taken into account in the design of a high-performance element. The present work aims at providing the basis for methodological analysis and comparison in such aspects, within the unified mathematical setting supplied by generalized standard material model and with special interest towards elastoplastic media. A critical review of the state-of-the-art computational methods is delivered in regard to variational formulations, selection of interpolation spaces, numerical solution strategies and numerical stability. Though those arguments are interrelated, a topic-oriented presentation is resorted to, for the very rich available literature to be properly examined. Finally, the performances of several significant mixed finite element formulations are investigated in numerical simulations.