Wound dressing products: A translational investigation from the bench to the market

Chronic skin wounds affect more than 40 million patients globally and represent a severe growing burden for the healthcare systems, with annual costs expected to exceed $15 billions by 2022. To satisfy the huge demand for effective wound care products, different types of wound dressings have been introduced on the market during the last decades. Based on “the moist wound healing theory” postulated by Prof Winter in 1962, bandages were initially designed to recreate the optimal wound environment to favor the healing process. Then, thanks to the advancements achieved in biomaterial design and processing, biotechnology, imaging and electronic fields, great effort has been devoted to the development of formulations able to actively participate to tissue healing. Indeed, both the literature and the market report the design of medicated wound dressings, i.e., wound care products releasing anti-microbial agents, anti-inflammatory drugs, or bioactive molecules. In this scenario, this review aims at critically describing the currently available wound care products, highlighting their proved effectiveness in wound management. Moreover, an overview of the main strategies exploited to design personalized wound dressings has been reported. Lastly, concerns on regulatory affairs and practical issues limiting the clinical translation of advanced research platforms have also been discussed

Adaptive Polynomial Harmonic Distortion Compensation in Current and Voltage Transformers Through Iteratively Updated QR Factorization

Measuring current and voltage harmonics has paramount importance for improving the power quality of distribution grids. However, the achieved accuracy strongly depends on the adopted instrument transformer (IT). This article proposes an adaptive technique that enables an effective compensation of both the filtering behavior and the harmonic distortion (HD) introduced by current and voltage transformers (VTs), namely the strongest nonlinear effect at low-order harmonics. The approach is based on a flexible, linear in the parameters polynomial modeling of HD in the frequency domain. Model complexity can be different from one harmonic to the other, and it is selected through an automatic iterative process to suit the nonlinear behavior at each specific harmonic order, while avoiding overfitting. In particular, the number of parameters is increased by progressively updating the QR factorization of the regressor matrix trough Householder reflections until a convergence condition is reached. Experimental tests performed on an inductive VT and current transformer (CT) highlight the effectiveness of the approach

A Low-Cost Approach to the Skin Effect Compensation in Cylindrical Shunts

In this paper the development of a new design solution for high-current shunt resistors is presented, which allows achieving very good accuracy while requiring a simple and low-cost manufacturing process. It is based on a solid cylinder having the voltage measurement circuit which runs through two holes drilled in the cylinder itself. Starting from the well-known expression of the current density in a cylindrical conductor, the frequency response of the shunt is obtained in closed form as a function of the geometric parameters. In turn, the positions of the voltage measurement terminals are chosen by optimizing the frequency response function over a specified range. A shunt prototype has been manufactured and its measurement performance has been evaluated. The experimental results confirm the validity of the approach and highlight the significant improvement with respect to the single-hole cylindrical shunt which has been recently proposed by the authors. The obtained measurement accuracy is noticeable when compared with the ease of manufacturing

Frequency-domain nonlinear modeling approaches for power systems components - A comparison

Harmonic simulations play a key role in studying and predicting the impact of nonlinear devices on the power quality level of distribution grids. A frequency-domain approach allows higher computational efficiency, which has key importance as long as complex networks have to be studied. However, this requires proper frequency-domain behavioral models able to represent the nonlinear voltage-current relationship characterizing these devices. The Frequency Transfer Matrix (FTM) method is one of the most widespread frequency domain modeling approaches for power system applications. However, others suitable techniques have been developed in the last years, in particular the X-parameters approach, which comes from radiofrequency and microwave applications, and the simplified Volterra models under quasi-sinusoidal conditions, that have been specifically tailored for power system devices. In this paper FTM, X-parameters and simplified Volterra approaches are compared in representing the nonlinear voltage-current relationship of a bridge rectifier feeding an ohmic-capacitive dc load. Results show that the X-parameters model reaches good accuracy, which is slightly better than that achieved by the FTM and simplified Volterra models, but with a considerably larger set of coefficients. Simplified Volterra models under quasi-sinusoidal conditions allows an effective trade-off between accuracy and complexity

Theory and Experimental Validation of Two Techniques for Compensating VT Nonlinearities

Inductive instrument transformers (ITs) are still the most used voltage and current sensors in power systems. Among the numerous applications that require their use, one of the most important is surely represented by harmonics measurement. In this case, the recent literature shows that, since they suffer from both a filtering behavior due to their dynamics and from nonlinear effects produced by their iron core, they can introduce errors up to some percent. This article wants to deeply investigate, in the very same experimental conditions, about the performance of two digital signal processing techniques, recently introduced for the improvement of harmonics measurements performed through ITs, namely, SINusoidal characterization for DIstortion COMPensation (SINDICOMP) and compensation of harmonic distortion through polynomial modeling in the frequency domain (PHD). These methods have been applied to two different voltage transformers, having different specifications, by using two measurement setups based on different architectures. The impact of the voltage generator employed during the identification on the achieved accuracy is theoretically and experimentally evaluated. Modified versions of SINDICOMP and PHD compensation, which are more robust against nonidealities of the measurement setup, are presented. The performances of the techniques are evaluated by adopting voltage waveforms similar to those that can be encountered during the normal operation in a real distribution grid

Hybrid injectable platforms for the in situ delivery of therapeutic ions from mesoporous glasses

Copper-containing bioactive glasses (Cu-MBGs) are attracting increasing interest as multifunctional agents for hard and soft tissue healing due to the ability of released copper ions to stimulate osteogenesis as well as angiogenesis and to impart anti-bacterial properties. The conjugation of these nanomaterials with a vehicle phase based on thermosensitive hydrogels represents an effective strategy to design non-invasive injectable devices for the in situ delivery of therapeutic ions from MBGs. In this contribution, Cu-containing MBGs were prepared by an aerosol-assisted spray-drying method (MBG_Cu 2%_SD) in the form of microspheres (surface area of ca 220m2 g−1) and through a sol-gel synthesis (MBG_Cu 2% _SG) in the form of spheroidal nanoparticles (surface area above 700m2 g−1). Both Cu-containing samples were able to release copper ions, although with different rates and percentage release. MBG_Cu 2%_SG released the total incorporated amount of Cu ions with a faster kinetics compared to MBG_Cu 2%_SD, that released approximately the 60% of copper. Cu-MBGs were incorporated with a final concentration of 20 mg/mL into a thermosensitive sol-gel system consisting of a novel amphiphilic poly(ether urethane) based on a commercialy available Poloxamer 407 (P407), with improved gelation ability, mechanical strength and stability in aqueous solution with respect to native P407. Cu-MBG-loaded hydrogels were characterised in terms of sol-to-gel transition temperature and time, injectability and stability in aqueous environment at 37 °C. The hybrid formulations showed fast gelation in physiological conditions (1 mL underwent complete sol-to-gel transition within 3–5 min at 37 °C) and injectability in a wide range of temperatures (5–37 °C) through different needles (inner diameter in the range 0.6–1.6 mm)

Oltre l’orientalismo e l’occidentalismo. La rappresentazione dell’Altro nello spazio euro-mediterraneo

I rapporti tra Oriente e Occidente sono stati per lungo tempo letti attraverso le lenti deformanti dell’orientalismo e dell’occidentalismo, che ne hanno confinato la complessità e la ricchezza in un immaginario costruito su stereotipi e luoghi comuni. In realtà, “Oriente” e “Occidente” sono soltanto concetti astratti che non definiscono una dimensione geografica, ma una dimensione culturale, quasi mitica, che ne rivela l’interdipendenza. In un mondo che vede moltiplicarsi le opportunità di confronto e di contatto con le diversità, anche grazie all’azione dei mass media, è urgente ripensare al rapporto tra Oriente e Occidente e andare oltre le reciproche, e distorte, rappresentazioni. Lo spazio del Mediterraneo può svolgere un ruolo fondamentale per interrompere il flusso di incomprensioni poiché, pur dividendo le due sponde, le ingloba entrambe. Solo superando l’impasse di una conoscenza superficiale alimentata dai pregiudizi e ricordando il comune patrimonio culturale dei paesi affacciati sul Mediterraneo, si potrà costruire una concreta opportunità di dialogo e incontro. Questo volume raccoglie gli interventi di studiosi provenienti da vari paesi del Mediterraneo, uniti nello sforzo di combattere le immagini distorte e di elaborare nuove categorie concettuali in grado di interpretare gli scenari contemporanei.The relations between the East and the West have been understood long time through the distorting lenses of Orientalism and Occidentalism, which have confined the complexity and richness of cultures in a collective imagination built on stereotypes and clichés. In fact, "East" and "West" are not just theoretical concepts that define a geographic dimension, but they have a cultural dimension, almost mythical, which reveals a strong interdependence. In the contemporary world the opportunities for discussion and contact with the diversity are multiplied, also with regards to the mass communication: but it is urgent to rethink the relationship between East and West and go over distorted representations. The Mediterranean area can play a key role in stopping the flow of misunderstandings because, while dividing the two sides, also incorporates them. Only by going beyond the impasse of a superficial knowledge nourished by prejudice and remembering the common cultural heritage of the countries bordering the Mediterranean, can be built a real opportunity for dialogue and encounter. This volume collects the work of scholars from various countries of the Mediterranean, all joined in the effort to combat the distorted images and develop new conceptual categories to interpreting the contemporary scenario

Model-based maximum power point tracking for photovoltaic panels: Parameters identification and training database collection

Module-level distributed maximum power point tracking (MPPT) represents an attractive solution for photovoltaic systems installed in dense urban areas, where panels are often subject to different solar irradiance levels. Model-based MPPT algorithms are particularly suitable for the purpose: they enable good steady-state accuracy and fast dynamics thanks to an underlying parametric model of the panel. The target of the present study is deeply investigating the estimation of the model parameters, and the collection of the training database, since they heavily affect overall performance. In this work, parameter values result by maximising energy production considering the training database; under some simplifications, it leads to a weighted least squares problem that can be easily solved. One of the main advantages is the robustness in the presence of some identification data that have been collected under partially shadowed conditions. Moreover, the possibility to gather the training database by running a perturb and observe MPPT is investigated and tested for the first time. Energy production is allowed also during this stage, thus opening the way to a periodic update of the parameters to follow degradation and time drift of the module. Experimental results show that performance is virtually the same as that obtained by computing parameters from a large set of volt-ampere characteristics

Oltre "orientalismo" e "occidentalismo": per un lessico della rappresentazione dell'altro

Orientalismo e occidentalismo sono termini che indicano come le immagini dell’Altro, soprattutto quelle costruite dalle istituzioni culturali, possono essere del tutto “ideologiche”, costruite a partire da operazioni arbitrarie di riduzione della complessità delle culture a pochi elementi, spesso selezionati e definiti in termini oppositivi e con la finalità di definire una rappresentazione della realtà autoconsolatoria e favorevole alla “nostra” parte. Questo Lessico intende aiutare a definire alcuni termini chiavi per affrontare la complessa questione della rappresentazione, conn particolare riguardo all'identità islamic

Investigating and Modeling the Harmonic Measurement Accuracy of Current Transformers

Overall measurement accuracy of current transformers is expressed by their accuracy class. When considering the fundamental component, it corresponds to ratio and phase error limits that are relaxed at small current values. As far as low-power current transformers, fixed ratio and phase error limits are prescribed at harmonic components. This paper shows, through numerical simulations, that this approach cannot represent the performance of current transformers in the presence of nonlinearity. A general method to model the behavior of harmonic ratio and phase errors is presented, regardless of the operating principle of the current transformer. This suggests an alternative approach to specify accuracy requirements at a given harmonic, which should depend on its relative magnitude with respect to the fundamental