A simple scheme for the inversion of a Preisach like hysteresis operator in saturation conditions

A class of operators based on a Prandtl-Ishilinskii operator with inverse in a closed form is presented. Conversely to those considered in the past, they describe the B - H constitutive equation and not the usual J - H link. This allows its application in numerical schemes for the description of nonlinear dynamic circuits in transient conditions, with low formulation effort and computational weight, with respect to the standard inversion of the operator. The model has been implemented into a numerical scheme describing a RL nonlinear and hysteretic circuit, outlining the effects of residual magnetization and coercive field on the global current dynamics. The model performances are preliminary compared to numerical model based on the standard numerical inversion of the operator, along with the experimental results of transient current analysis

A practical engineering approach to the design and manufacturing of a mini kW blade wind turbine : definition, optimisation and CFD analysis

A practical engineering approach to the design of a 60 kW wind generator with improved performances is presented. The proposed approach relies on the use of a specific, “ad hoc” developed software, OPTIWR (Optimization Software), expressly conceived to define an “optimum” rotor configuration in the framework of the blade element-momentum theory. Starting from an initial input geometric configuration (corresponding to an already existing 50 kW turbine) and for given values of the wind velocity Vwind and of the advance ratio X = Vwind/ΩR (where Ω is the blade rotational speed and R is the propeller radius), this software is used to determine iteratively the optimized distributions of chords and twists which can guarantee a constant value of the socalled axial induction factor a = 1/3 along the blade. The output configuration is then converted into a CAD model to be used, in turn, as input data for a CFD commercial software. With this tool the relative rotational motion between the fluid and the wind turbine are simulated resorting to a MRF (Moving Reference Frame) technique (for which continuity and momentum equations are solved in a rotating reference frame). The outcomes of the numerical simulations are then used to verify the improved performances of the optimized configuration and to which extent the CFD data agree with “expected” behaviours (i.e. performances predicted on the basis of the simplified model). Finally, some details about the construction technique used to turn the optimized configuration into an effective working prototype are provided, in conjunction with a critical discussion of suitable production methods for composite components

LivHeart: A Multi Organ-on-Chip Platform to Study Off-Target Cardiotoxicity of Drugs Upon Liver Metabolism

The drug discovery and development process is still long, costly, and highly risky. The principal attrition factor is undetected toxicity, with hepatic and cardiac toxicities playing a critical role and being the main responsible of safety-related drug withdrawals from the market. Multi Organs-on-Chip (MOoC) represent a disruptive solution to study drug-related effects on several organs simultaneously and to efficiently predict drug toxicity in preclinical trials. Specifically focusing on drug safety, different technological features are applied here to develop versatile MOoC platforms encompassing two culture chambers for generating and controlling the type of communication between a metabolically competent liver model and a functional 3D heart model. The administration of the drug Terfenadine, a cardiotoxic compound liver-metabolized into the noncardiotoxic Fexofenadine, proved that liver metabolism and a fine control over drug diffusion are fundamental to elicit a physio-pathological cardiac response. From these results, an optimized LivHeart platform is developed to house a liver model and a cardiac construct that can be mechanically trained to achieve a beating microtissue, whose electrophysiology can be directly recorded in vitro. The platform is proved able to predict off-target cardiotoxicity of Terfenadine after liver metabolism both in terms of cell viability and functionality

Structure and Properties of DNA Molecules Over The Full Range of Biologically Relevant Supercoiling States

Topology affects physical and biological properties of DNA and impacts fundamental cellular processes, such as gene expression, genome replication, chromosome structure and segregation. In all organisms DNA topology is carefully modulated and the supercoiling degree of defined genome regions may change according to physiological and environmental conditions. Elucidation of structural properties of DNA molecules with different topology may thus help to better understand genome functions. Whereas a number of structural studies have been published on highly negatively supercoiled DNA molecules, only preliminary observations of highly positively supercoiled are available, and a description of DNA structural properties over the full range of supercoiling degree is lacking. Atomic Force Microscopy (AFM) is a powerful tool to study DNA structure at single molecule level. We here report a comprehensive analysis by AFM of DNA plasmid molecules with defined supercoiling degree, covering the full spectrum of biologically relevant topologies, under different observation conditions. Our data, supported by statistical and biochemical analyses, revealed striking differences in the behavior of positive and negative plasmid molecules

PERFORMANCES OF A SMALL HYPERSONIC AIRPLANE (HYPLANE)

In the present work a preliminary performance study regarding a small hypersonic airplane named HyPlane is presented. It is designed for long duration sub-orbital space tourism missions, in the frame of the Space Renaissance (SR) Italia Space Tourism Program. The vehicle is also consistent with a point-to-point medium range hypersonic trip, within the “urgent business travel” market segment. The design of such a hypersonic airplane is based on the concept of integrating available technologies developed for aeronautical and space atmospheric re-entry systems. The vehicle, characterized by high aerodynamic efficiency and low wing loading, is able to provide aerodynamic stability and manoeuvrability along the flight path and to produce a reduced sonic boom during cruise and supersonic descent approach, ensuring a very limited environmental impact. HyPlane, powered by Turbine Based Combined Cycle (TBCC) engines plus a throtteable Rocket, is able to perform Horizontal Takeoff and Horizontal Landing (HTHL) on runways. Aerodynamic and propulsive performances for the different flight regimes encountered during the missions are studied. Aerodynamic heating effects are analyzed, in order to identify suitable structures and materials design to sustain the hypersonic flight conditions. Different flight paths are also investigated, including hypersonic cruise and sub-orbital parabolic trajectories, which provide Space tourists with the opportunity of long duration missions, offering short and repeated periods of low-gravity, in the high stratosphere where a large view of the Earth is ensured

Cortisol levels of shelter dogs in animal assisted interventions in a prison: An exploratory study

Previous studies regarding the Animal Assisted Interventions (AAI) have mainly focused on the beneficial effects of human–animal interactions on human health; whereas the impact of such activities on the welfare of the animals involved has received limited attention. So far, few studies have addressed this issue by evaluating the physiological and behavioral reactions of therapy dogs during the interventions. The aim of this study was to evaluate the potential effect of AAI on the cortisol levels of shelter dogs. Five dogs participated in weekly AAI working activities with adult inmates held at a prison of the South of Italy for two months. Saliva samples were collected every two weeks in three conditions: at the kennel (baseline), after transportation and at the end of the working sessions. The results revealed a significant decrease in the cortisol baseline at the end of the AAI program, suggesting that the activities carried out with humans and in a different environment could improve the welfare of dogs housed in kennels. Moreover, we found that transportation significantly increased subjects’ cortisol levels, suggesting that it is a critical phase that deserves particular care

Enhancing all-in-one bioreactors by combining interstitial perfusion, electrical stimulation, on-line monitoring and testing within a single chamber for cardiac constructs

Tissue engineering strategies have been extensively exploited to generate functional cardiac patches. To maintain cardiac functionality in vitro, bioreactors have been designed to provide perfusion and electrical stimulation, alone or combined. However, due to several design limitations the integration of optical systems to assess cardiac maturation level is still missing within these platforms. Here we present a bioreactor culture chamber that provides 3D cardiac constructs with a bidirectional interstitial perfusion and biomimetic electrical stimulation, allowing direct cellular optical monitoring and contractility test. The chamber design was optimized through finite element models to house an innovative scaffold anchoring system to hold and to release it for the evaluation of tissue maturation and functionality by contractility tests. Neonatal rat cardiac fibroblasts subjected to a combined perfusion and electrical stimulation showed positive cell viability over time. Neonatal rat cardiomyocytes were successfully monitored for the entire culture period to assess their functionality. The combination of perfusion and electrical stimulation enhanced patch maturation, as evidenced by the higher contractility, the enhanced beating properties and the increased level of cardiac protein expression. This new multifunctional bioreactor provides a relevant biomimetic environment allowing for independently culturing, real-time monitoring and testing up to 18 separated patches