Numerical Investigation of the Effects of Orientation and Gravity in a Closed Loop Pulsating Heat Pipe

The Closed Loop Pulsating Heat Pipe (CLPHP) is a very promising passive two-phase heat transfer device for relatively high heat fluxes (up to 30 W/cm²) patented by Akachi (1990, 1993). Although the CLPHP has a simple structure, its working principles are very complex compared to the standard heat pipe with a porous wick. One of the most debated issues deals on how the thermal performance is affected by the inclination and by the action of different gravity fields (terrestrial, lunar, martian and microgravity). Even if the internal tube diameter satisfies the conventional slug flow regime requirement on the Bond number, gravity force still plays an important role on the PHP behaviour. Heat input and the number of turns are two of the most important indirect parameters linked to the gravity issue. A complete numerical campaign has been performed by means of a FORTRAN code at different inclination angles and gravity levels on various PHP. The numerical model is able to estimate both the hydrodynamic and the thermal performance of a CLPHP with different working fluids. The analysis shows that the effect of local pressure losses due to bends is important and must be taken into account, in particular in the horizontal operation which is the reference point for space applications. Numerical results are matched with the experimental data quoted in literature and both good qualitative and quantitative agreement have been found.     

Path Planning Strategies for UAVS in 3D Environments

The graph-search algorithms developed between 60s and 80s were widely used in many fields, from robotics to video games. The A* algorithm shall be mentioned between some of the most important solutions explicitly oriented to motion-robotics, improving the logic of graph search with heuristic principles inside the loop. Nevertheless, one of the most important drawbacks of the A* algorithm resides in the heading constraints connected with the grid characteristics. Different solutions were developed in the last years to cope with this problem, based on post-processing algorithms or on improvements of the graph-search algorithm itself. A very important one is Theta* that refines the graph search allowing to obtain paths with “any” heading. In the last two years, the Flight Mechanics Research Group of Politecnico di Torino studied and implemented different path planning algorithms. A Matlab based planning tool was developed, collecting four separate approaches: geometric predefined trajectories, manual waypoint definition, automatic waypoint distribution (i.e. optimizing camera payload capabilities) and a comprehensive A*-based algorithm used to generate paths, minimizing risk of collision with orographic obstacles. The tool named PCube exploits Digital Elevation Maps (DEMs) to assess the risk maps and it can be used to generate waypoint sequences for UAVs autopilots. In order to improve the A*-based algorithm, the solution is extended to tri-dimensional environments implementing a more effective graph search (based on Theta*). In this paper the application of basic Theta* to tri-dimensional path planning will be presented. Particularly, the algorithm is applied to orographic obstacles and in urban environments, to evaluate the solution for different kinds of obstacles. Finally, a comparison with the A* algorithm will be introduced as a metric of the algorithm performances.     

Multimod Data Manager: a tool for data fusion

Nowadays biomedical engineers regularly have to combine data from multiple medical imaging modalities, biomedical measurements and computer simulations and this can demand the knowledge of many specialised software tools. Acquiring this knowledge to the depth necessary to perform the various tasks can require considerable time and thus divert the researcher from addressing the actual biomedical problems. The aim of the present study is to describe a new application called the Multimod Data Manager, distributed as a freeware, which provides the end user with a fully integrated environment for the fusion and manipulation of all biomedical data. The Multimod Data Manager is generated using a software application framework, called the Multimod Application Framework, which is specifically designed to support the rapid development of computer aided medicine applications. To understand the general logic of the Data Manager, we first introduce the framework from which it is derived. We then illustrate its use by an example--the development of a complete subject-specific musculo-skeletal model of the lower limb from the Visible Human medical imaging data to be used for predicting the stresses in the skeleton during gait. While the Data Manager is clearly still only at the prototype stage, we believe that it is already capable of being used to solve a large number of problems common to many biomedical engineering activities.     

Evaluation of Controlled Ovarian Stimulation Protocols in Patients with Normal and Low Ovarian Reserve: Analyses of miRNAs and Selected Target Genes Involved in the Proliferation of Human Cumulus Cells and Oocyte Quality

The oocyte and the surrounding cumulus cells (CCs) are deeply linked by a complex bidirectional cross-talk. In this light, the molecular analysis of the CCs is nowadays considered to be precious in providing information on oocyte quality. It is now clear that miRNAs play a key role in several ovarian functions, such as folliculogenesis, steroidogenesis, and ovulation. Thus, in this study, specific miRNAs, together with their target genes, were selected and investigated in CCs to assess the response of patients with normal (NR) and low (LR) ovarian reserve to two different controlled ovarian stimulation (COS) protocols, based on rFSH and hMG. Moreover, a Fourier transform infrared microspectroscopy (FTIRM) analysis was performed to evaluate DNA conformational changes in CCs and to relate them with the two COS protocols. The results evidenced a modulation of the expression of miRNAs and related target genes involved in CCs’ proliferation, in vasculogenesis, angiogenesis, genomic integrity, and oocyte quality, with different effects according to the ovarian reserve of patients. Moreover, the COS protocols determined differences in DNA conformation and the methylation state. In particular, the results clearly showed that treatment with rFSH is the most appropriate in NR patients with normal ovarian reserve, while treatment with hMG appears to be the most suitable in LR patients with low ovarian reserve.     

Subcritical water extraction of thyreostats from bovine muscle followed by liquid chromatography-tandem mass spectrometry

Thyreostats can be used fraudulently to promote a rapid increase in weight of breeding animals at low cost. Their severe toxicological effects impose the development of reliable analytical methods to be used in monitoring plans. This work describes an alternative approach to isolate residues of thiouracil, methyl-thiouracil, propyl-thiouracil, phenyl-thiouracil, tapazole and mercaptobenzimidazole from bovine muscle tissue. The developed procedure is based on the following three steps: i) matrix solid-phase dispersion with C₁₈ for the preliminary sample preparation; ii) subcritical water extraction (SWE) at 160°C and 100 bar; iii) clean-up on an Oasis HLB cartridge. The quantitative determination was performed by LC-MS/MS in dual polarity ionization by using internal standardization. The SWE-LC-MS/MS method was validated according to the identification criteria of the Commission decision 2002/657/EC. The relative recoveries ranged from 72 to 97%; within-lab reproducibility was less than 18%. The decision limit and the detection capability of all analytes were below the recommended concentration, set at 10 µg kg^?1, but the validation results demonstrated that this method could only be applied for screening of thiouracil and methyl-thiouracil.

Besides the analytical advantages related to the use of water as solvent extraction, the procedure allowed significant removal of lipids, whose detrimental effects on instrumentation and MS sensitivity are well-known.     

Synthesis of magnetic tunnel junctions with full in situ atomic layer and chemical vapor deposition processes

Magnetic tunnel junctions, i.e. the combination of two ferromagnetic electrodes separated by an ultrathin tunnel oxide barrier, are core elements in a large variety of spin-based devices. We report on the use of combined chemical vapor and atomic layer deposition processes for the synthesis of magnetic tunnel junctions with no vacuum break. Structural, chemical and morphological characterizations of selected ferromagnetic and oxide layers are reported, together with the evidence of tunnel magnetoresistance effect in patterned Fe/MgO/Co junctions.     

The Design of GDPR-Abiding Drones Through Flight Operation Maps: A Win–Win Approach to Data Protection,Aerospace Engineering,and Risk Management

Minds and Machines - Risk management is a well-known method to face technological challenges through a win–win combination of protective and proactive approaches, fostering the collaboration...     

Calcium-Dependent Cytosolic Phospholipase A2α as Key Factor in Calcification of Subdermally Implanted Aortic Valve Leaflets

Calcium-dependent cytosolic phospholipase A2α (cPLA2α) had been previously found to be overexpressed by aortic valve interstitial cells (AVICs) subjected to in vitro calcific induction. Here, cPLA2α expression was immunohistochemically assayed in porcine aortic valve leaflets (iAVLs) that had undergone accelerated calcification subsequent to 2- to 28-day-long implantation in rat subcutis. A time-dependent increase in cPLA2α-positive AVICs paralleled mineralization progression depending on dramatic cell membrane degeneration with the release of hydroxyapatite-nucleating acidic lipid material, as revealed by immunogold particles decorating organelle membranes in 2d-iAVLs, as well as membrane-derived lipid byproducts in 7d- to 28d-iAVLs. Additional positivity was detected for (i) pro-inflammatory IL-6, mostly exhibited by rat peri-implant cells surrounding 14d- and 28d-iAVLs; (ii) calcium-binding osteopontin, with time-dependent increase and no ossification occurrence; (iii) anti-calcific fetuin-A, mostly restricted to blood plasma within vessels irrorating the connective envelopes of 28d-iAVLs; (iv) early apoptosis marker annexin-V, limited to sporadic AVICs in all iAVLs. No positivity was found for either apoptosis executioner cleaved caspase-3 or autophagy marker MAP1. In conclusion, cPLA2α appears to be a factor characterizing AVL calcification concurrently with a distinct still uncoded cell death form also in an animal model, as well as a putative target for the prevention and treatment of calcific valve diseases.