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Impact of Endovascular Aortic Repair on Aortic Stiffness: Preliminary Results from a Prospective In Vivo Study Following EVAR
No full textBackground: Aortic stiffness (AoS) is an established predictor of cardiovascular morbidity and mortality. Endovascular aneurysm repair (EVAR) introduces a rigid stent-graft into the aorta, potentially increasing AoS and impairing subendocardial perfusion. This prospective study aimed to evaluate changes in AoS and myocardial perfusion following EVAR, measured by carotid-to-femoral pulse wave velocity (cf-PWV) and the Subendocardial Viability Ratio (SEVR), and examined the influence of graft length on post-operative cf-PWV and SEVR. Methods: From October 2023 to April 2025, 38 patients undergoing elective EVAR were prospectively enrolled. Cf-PWV and the SEVR were measured <72 h preoperatively and 7 days postoperatively using the PulsePen® device. Descriptive statistics were used to summarize baseline characteristics. Data were assessed for normality with the Shapiro–Wilk test; non-normally distributed variables were analysed using the Wilcoxon signed-rank test and presented as median [interquartile range, IQR], while normally distributed variables were analysed using paired t-tests and presented as mean ± standard deviation (SD). Linear regression was applied to evaluate associations between graft length and postoperative changes in cf-PWV and SEVR. Results: Cf-PWV increased significantly after EVAR, with a median within-patient change of 1.0 m/s [IQR 3.1] (p < 0.001), corresponding to a 10.6% increase. The SEVR decreased significantly by 15.1% (p = 0.006). Graft length correlated positively with cf-PWV change, with a 0.2% increase in cf-PWV per millimetre of graft length (r = 0.41; p = 0.029), but not with SEVR (r = 0.058, p = 0.763). Conclusions: EVAR was associated with increased AoS and reduced subendocardial perfusion, with greater stiffness changes observed in patients receiving longer grafts. These preliminary findings highlight important haemodynamic consequences of EVAR and may inform patient selection, postoperative management, and the development of future stent-graft designs to mitigate long-term cardiovascular risk
Anti-adhesive bioactive glasses via oligosiloxane deposition and plasma treatment
No full textThe development of antimicrobial and anti-adhesive surfaces presents a significant challenge in the advancement of biomaterials, particularly in the context of bioactive materials for bone substitution. This research focuses on the deposition of an anti-adhesive coating using an atmospheric dielectric barrier discharge plasma technology for the surface of two bioactive glasses, SBA2 and S53P4. The obtained materials were characterized from a morphological-compositional point of view, evidencing a uniform coating with a pillar structure. The surface properties, investigated through wettability, roughness, and zeta potential analyses, showed an increased hydrophobicity and the exposition of -NH2 groups. Moreover, since the presence of the coating and plasma treatment can interfere with the bioactivity mechanism, in vitro bioactivity test was performed, highlighting an increased bioactivity kinetics. The surface adhesion behavior of a Multidrug-resistant bacterial strain, Staphylococcus aureus, was estimated by exploiting a preliminary test after 90 min of incubation. The results showed a significant decrease in the colonies attached to the surfaces for both treated glasses compared to the pristine samples. This decrement in bacterial attachment is attributed to the conferment of hydrophobic properties, with a possible role also played by the obtained roughness. This study presents an innovative approach that integrates atmospheric plasma surface modification with bioactive glass technology to develop bone substitute materials that both prevent bacterial colonization and maintain their regenerative capabilities
Unsteady surface pressure measurements of propeller-wing interaction with a MEMS-embedded sleeve
No full textThis work investigates the unsteady aerodynamic interaction that arises from the impingement of a propeller slipstream on a wing. To this end, an innovative measuring device for unsteady pressure is deployed, comprising a flexible printed circuit board sleeve embedded with MEMS pressure sensors and microphones. The device performance is validated against conventional measurement techniques. The wing is a benchmarked NACA 633018 airfoil-based model, and the propeller is the TUD-XPROP-S. In addition to pressure measurements, oil flow visualizations are performed to elucidate the flow pattern on the wing when the propeller operates at advance ratios of 0.8 and 1.8, and nominal blade pitch angles of 30° and 45°. The measurements reveal the formation of a laminar separation bubble on the portion of the wing not washed by the propeller slipstream. The flow is seen to remain attached on the advancing blade side, at least for the tested angles of attack. The microphone measurements capture the trace of the propeller’s tip vortices over the wing and the deformation of the slipstream over the wing. This work serves a dual purpose. Firstly, presenting an innovative measuring device for unsteady pressure, as the sensor-embedded sleeve requires minimal installation efforts and allows for a comprehensive measurement of the unsteady surface pressure field. Secondly, discussing the complex spatio temporal interaction that is formed from the impingement of a propeller slipstream onto a wing
Design Guidelines for Active Power Filters Operating in Disturbed Industrial Environments
No full textRegenerative testing systems of AC–AC industrial power converters (diode or thyristor rectifier
and inverter) at the end of the production line are common solutions to reduce the energy drawn from the
grid during the testing. However, they inherently introduce severe harmonic distortion, causing disturbances
for all local loads. Shunt-type active power filters (APFs) are widely adopted to mitigate these issues.
Since the APF is an add-on for the testing system in mass production facilities, it must be cost effective
and with high efficiency for not affecting the overall losses for the testing. Moreover, higher switching
frequencies are often used to reduce grid-interfacing filter size, further impacting APF efficiency. As the
industrial environments are highly disturbed, the APF operation must be extremely robust against these
disturbances. In light of the aforementioned issues, this article provides guidelines for the design of an
APF intended to operate in an industrial environment characterized by significant electrical disturbances.
In particular, the article demonstrates how the adoption of a dedicated discontinuous pulsewidth modulation
(DPWM) technique for APFs, namely APFGDPWM, allows minimizing the impact of the APF on power line
consumption and reducing the stress on the APF semiconductors and on the filters for grid interfacing. Unlike
other DPWM strategies in the literature designed for APFs, APFGDPWM proves to be robust against high
frequency disturbances circulating on the power lines. Moreover, a design procedure for the differential mode
(DM) LCL filter is proposed and used to build two distinct prototypes: an APF implementing space vector
pulsewidth modulation (SVPWM) and an APF using APF-GDPWM. Experimental tests are conducted on an
industrial prototype (TRL 9), 100 kVA two-level APF interfaced to the grid through the previously designed
DM LCL filters, while compensating for the distorted input current of a regenerative system testing 260 kVA
power converter
From Coarse Single Theoretical to Fine Multiple Practical: Machine Learning-Empowered Real-Time Communications
Get PDFL'abstract è presente nell'allegato / the abstract is in the attachmen
La Magdeleine
No full textPubblicazione del progetto in Alessandro Bianco, Riconnettersi alla valle, in "Casa Naturale", n. 140, gennaio-febbraio 202
Are Ultrathin Stents Optimal for Bifurcation Lesions? Insights From Computational Modeling of Provisional and DK‐Crush Techniques
No full textBackground: Complex coronary bifurcation lesions remain challenging in percutaneous coronary intervention, with stent design and deployment strategy influencing clinical outcomes. Aims: This study compares the mechanical and hemodynamic performance of the ultrathin-strut Orsiro and thin-strut Xience Sierra stent in provisional side branch (PSB) and double kissing crush (DKC) techniques. Methods: We used finite element analyses of bifurcation stent deployment to assess malapposition, ostium clearance, and arterial wall stress for both techniques. Computational fluid dynamics simulations quantified the luminal exposure to low time-averaged endothelial shear stress (TAESS 1000 s−1). Results: In PSB, Orsiro showed higher malapposition (13.0% vs. 9.6%) but improved SB ostium clearance (77% vs. 64%) and lower low-TAESS exposure (30.3% vs. 33.6%) compared to Xience. Orsiro also produced higher arterial wall stresses, particularly during kissing balloon inflation. In DKC, differences in malapposition and ostium clearance diminished between stents, though Orsiro retained a hemodynamic advantage with lower low-TAESS (28.2% vs. 36.3%). Conclusions: Stent design influenced outcomes more strongly in PSB, where anatomical interaction and platform-specific behavior impacted both structural and hemodynamic results. In DKC, procedural complexity minimized those differences, making the stenting technique the primary performance driver. Nonetheless, Orsiro consistently preserved more favorable flow conditions. These findings highlight the need to match device selection with lesion characteristics in PSB, while in DKC, optimizing procedural steps may have a greater impact than the choice of stent platform