Higher Institute on Territorial Systems for Innovation
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Polyester artificial ligament modified with a polyphenol-zinc layer for controlled and targeted release of ciprofloxacin
Get PDFTendon and ligament injuries often necessitate surgical intervention with the use of artificial implants due to their complex nature and the difficulties associated with natural tissue regeneration. This study investigates a novel surface modification method for polyester artificial ligaments (PEAL) to enhance their antimicrobial properties and biocompatibility. A polyphenol-zinc layer was synthesized on PEAL using epigallocatechin gallate (EGCG) and zinc cations, which allowed for the adsorption of ciprofloxacin (CIPRO) to achieve prolonged antibacterial activity. Comprehensive analyses, including UV–Vis spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS), confirmed the successful synthesis of the layer and the drug adsorption. The modified PEAL exhibited significant improvements in hydrophilicity, antioxidant capacity, and a sustained release of CIPRO over four hours. Antimicrobial tests demonstrated enhanced effectiveness against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus, with the highest inhibition rate observed for E. coli. Microbiological studies also demonstrated the ability of the modified PEAL to inhibit biofilm formation on their surface. Cytotoxicity studies indicated minimal toxicity for the modified samples, supporting their biocompatibility and potential for biomedical applications. Expression studies of inflammatory markers in two different cell lines showed no negative impact on the cellular inflammatory response. This innovative approach presents a promising solution for reducing infection risks and improving outcomes in the repair of the musculoskeletal system
Impact of Control Surface Stiffness on Aeroelastic Divergence and Reversal
No full textThis study addressed a gap in traditional aeroelastic models by incorporating the finite torsional stiffness of control surfaces within an extended two-degree-of-freedom analytical framework. By deriving the governing equations and evaluating the static aeroelastic phenomena of Divergence and Control Surface Reversal, the
study demonstrated the significance of including control surface hinge stiffness, which has been typically neglected or oversimplified in existing literature. The results show that ignoring the finite stiffness of the control surface can lead to nonconservative estimations, notably overestimating control surface effectiveness and the associated reversal speed.
The analytical outcomes revealed that a decrease in control surface torsional stiffness relative to the main aerodynamic surface accelerates the onset of Control Surface Reversal. This finding
underscores the importance of precise stiffness characterization in the design phase, especially for critical aeroelastic assessment
Optimality of Vaccination for an SIR Epidemic with an ICU Constraint
Get PDFThis paper studies an optimal control problem for a class of SIR epidemic models, in scenarios in which the infected population is constrained to be lower than a critical threshold imposed by the intensive care unit (ICU) capacity. The vaccination effort possibly imposed by the health-care deciders is classically modeled by a control input affecting the epidemic dynamic. After a preliminary viability analysis, the existence of optimal controls is established, and their structure is characterized by using a state-constrained version of Pontryagin’s theorem. The resulting optimal controls necessarily have a bang-bang regime with at most one switch. More precisely, the optimal strategies impose the maximum-allowed vaccination effort in an initial period of time, which can cease only once the ICU constraint can be satisfied without further vaccination. The switching times are characterized in order to identify conditions under which vaccination should be implemented or halted. The uniqueness of the optimal control is also discussed. Numerical examples illustrate our theoretical results and the corresponding optimal strategies. The analysis is eventually extended to the infinite horizon by Γ-convergence arguments
Digital Fairness in Satellite IoT Systems Based on NOMA With Nonideal SIC
No full textAchieving digital fairness through nonorthogonal multiple access (NOMA) is a critical challenge in modern 5G/6G wireless systems, particularly for satellite uplinks supporting the Internet of Things (IoT) devices across wide coverage areas. The variation in link budgets across space and time increases the risk of unequal access, allowing only a subset of users to achieve sufficiently high transmission rates. This work examines a coordinated uplink NOMA systems to equalize IoT user rates. It also incorporates the impact of imperfect successive interference cancellation (SIC) to reflect practical scenarios. For single-slot NOMA, the optimal SIC ordering to maximize the minimum user rate is determined. For multislot NOMA, relevant to satellite scenarios, a user rate equalization algorithm is proposed and analyzed numerically, assessing the tradeoff between user rates and receiver complexity. The proposed algorithm addresses multislot scheduling constraints with SIC limitations—a critical aspect of fairness in practical systems—by leveraging temporal dynamics to achieve fair resource allocation
Storie di innovazione sociale
Get PDFI temi e le storie del sociale hanno un peso e un’influenza crescenti capaci di generare impatti, cambiare narrative, incidere sull’economia, anche perché, a differenza dell’innovazione aziendale, l’innovazione sociale propone un modo altro di creare valore, con minore attenzione al profitto finanziario e maggiore enfasi sulle esigenze o necessità reali. La capacità di innovare è legata a vari fattori, tra cui la disponibilità di risorse, la cultura organizzativa e la capacità di apprendimento collettivo. Le innovazioni che sono sociali sia nei loro fini sia nei mezzi con cui sono realizzate emergono spesso in contesti di alta coesione sociale e fiducia reciproca, sono il risultato di un processo che coinvolge non solo la creatività, ma anche la capacità di tradurre le idee in azioni concrete
Design of a High Step-Up Partial-Power Quadratic DC-DC Converter for Wide-Voltage Range Photovoltaic Applications
Get PDFThis work presents the analysis, design, and simulation of a new multi-stage Partial Power Processing (PPP) converter with Input-Parallel-Output-Series (IPOS) topology for photovoltaic (PV) applications. An ad hoc design flow was developed to assist in the converter design in the 15V-45V input voltage range and 0 W-680 W power range, while simultaneously optimizing the efficiency at the desired rated voltage. The PPP approach enables part of the power to bypass the converter, achieving high efficiency and reduced component stresses. The integration of multi-stage and PPP approaches allows the achievement of a flat efficiency curve across the entire voltage range, a desirable feature for PV applications. The simulation results demonstrate a California Energy Commission (CEC) weighted efficiency of 97.2 % and European (EURO) efficiency of 96.8 % at rated voltage
Evaluation of fracture properties by coupling digital image correlation and Finite Fracture Mechanics
Get PDFCrack initiation in flattened disks under compression containing either a central or eccentric circular hole is investigated through the Finite Fracture Mechanics (FFM) approach. An implementation of the FFM criterion based on digital image correlation (DIC) full-field measurement is proposed. The coupling between FFM and DIC is provided through boundary conditions taken from the measured displacement fields. This approach offers a more accurate representation of the actual loading conditions compared to the use of idealized prescribed force or displacement in standard FFM implementations. Furthermore, by exploiting the value of the critical energy release rate obtained from the stable crack growth phase analysis, this method enables precise estimations of the inherent material strength and critical crack advance
A Human-Vector Susceptible–Infected–Susceptible Model for Analyzing and Controlling the Spread of Vector-Borne Diseases
Get PDFWe propose an epidemic model for the spread of vector-borne diseases. The model, which is built extending the classical susceptible-infected-susceptible model, accounts for two populations -humans and vectors- and for cross-contagion between the two species, whereby humans become infected upon interaction with carrier vectors, and vectors become carriers after interaction with infected humans. We formulate the model as a system of ordinary differential equations and leverage monotone systems theory to rigorously characterize the epidemic dynamics. Specifically, we characterize the global asymptotic behavior of the disease, determining conditions for quick eradication of the disease (i.e., for which all trajectories converge to a disease-free equilibrium), or convergence to a (unique) endemic equilibrium. Then, we incorporate two control actions: namely, vector control and incentives to adopt protection measures. Using the derived mathematical tools, we assess the impact of these two control actions and determine the optimal control policy
Food Loss and Waste in Agri-Food Systems: a multi-scale analysis of the impacts on the Water-Energy-Food-Ecosystem Nexus
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