5 research outputs found
A Design Pattern for translating UML software models into IEC 61131-3 Programming Languages
No full textThe paper deal with a deep analysis and application of object-oriented methodologies for the design process of industrial machine controllers. The process pass thought the phases of (1) conceptual model development of the software artifacts, and (2) model code deployment for the automation system target, which is in general a Programmable Logic Controller (PLC) compliant with the international standard IEC 61131-3 for programming languages. The paper describes a design pattern for the software conceptual model deployment, with a particular emphasis on practical requirements enforced by PLC of different brands. In fact, IEC 61131-3 compliance provides a common ``look-and-feel'' for programming languages, but does not guarantee straightforward code portability between different PLC vendors. The paper has a great focus on applications and provides an example, based on a generic flow-pack machine, to better explain the proposed methodology
An engineering process for the mechatronic development of industrial automation systems
No full textThis paper deals with the development process of an industrial application for the manufacturing of artefacts and products. In particular, a new engineering process tackling the whole machine life-cycle, from the user requirements capture, the project conceptual development to the final machine delivery and acceptance tests, is presented. The process is particularly tailored to the development of automated machines for the beverage and liquid food packaging market, and it is illustrated with a real case study developed in cooperation with a market leader machine manufacturer
Folding and stacking defects of graphene flakes probed by electron nanobeam
No full textCombining nanoscale imaging with local electron spectroscopy and diffraction has provided direct
information on folding and stacking defects of graphene flakes produced by unrolled multi-walled
carbon nanotubes. Structural data obtained by nanoarea electron diffraction complemented with
systematic electron energy loss spectroscopy measurements of the surface plasmon losses of single
flakes show the presence of flat bilayer regions coexisting with folded areas where the topology of
buckled graphene resembles that of warped carbon nanostructures
Sviluppo e caratterizzazione di materiali nano-rinforzati per applicazioni odontoiatriche
No full textIn questa tesi di dottorato, si sono investigate diverse strategie per migliorare la durata dei restauri dentali. Nonostante tutti i progressi nella odontoiatria conservativa negli ultimi anni, i compositi a base di resina continuano ad avere un alto tasso di fallimento. Una delle principali ragioni è lo sviluppo di micro-infiltrazioni batteriche lungo i margini del restauro e, di conseguenza, la formazione di carie secondarie ricorrenti.
In particolare, questo lavoro può essere diviso in due sezioni principali: (i) lo sviluppo e la caratterizzazione di adesivi contenenti composti antibatterici; (ii) lo sviluppo e la caratterizzazione di compositi dentali a base di resina contenenti diversi riempitivi al fine di migliorarne le prestazioni.
Nella prima parte di questa tesi, sono stati selezionati quattro monomeri bis-quaternari di-metacrilati antibatterici polimerizzabili (bis-QAMs; ovvero DDE, DDPyMMA, DDMAPMA e DDM), sviluppati da Fanfoni et al. [1], al fine di attribuire proprietà antimicrobiche a due diversi agenti adesivi commerciali, ScotchBond Multipurpose e Scotchbond Universal, un adesiv0 3-steps etch-and-rinse e un adesivo universale self-etch, rispettivamente. Per un eventuale utilizzo clinico, è necessario che l'aggiunta di queste molecole non riduca la resistenza di adesione dell'adesivo, anche a lungo termine, e soprattutto che l'attività antibatterica sia preservata dopo la polimerizzazione. I risultati della forza di adesione (μTBS), sia a tempo 0 che dopo un invecchiamento termomeccanico in vitro (simulando 5 anni di servizio clinico), e la valutazione antibatterica in vitro (contro Streptococcus mutans) hanno dimostrato che il sistema adesivo Scotchbond Multipurpose è più adatto per l'incorporazione di queste molecole, in particolare DDMAPMA può quindi essere identificato come il miglior monomero antibatterico, che non influisce sulle proprietà meccaniche e superficiali.
La seconda parte di questo progetto si è concentrata sullo sviluppo e la caratterizzazione di materiali compositi dentali nano-rinforzati mediante l'incorporazione di idrossiapatite (nHAp) di dimensioni nanometriche come riempitivo, che presenta proprietà antibatteriche e di remineralizzazione grazie alla presenza di un vetro bioattivo (BGMS10), sintetizzato da Bellucci et al. [2]. L'analisi mediante microscopia elettronica a scansione (SEM) e microscopia elettronica a trasmissione (TEM) delle polveri di filler, HAp e BGMS10, ha confermato la presenza di particelle nanoscopiche per entrambi i riempitivi. La caratterizzazione meccanica ha mostrato che i compositi sperimentali realizzati con diverse proporzioni resina/riempitivo (R2/HAp-BGMS10) non presentavano valori adeguati di resistenza alla flessione e micro-durezza Vickers per il loro utilizzo. Tuttavia, è interessante notare che i valori di durezza dei compositi sperimentali nelle condizioni che simulano l'ambiente orale (immersione in acqua distillata a 37°C per un totale di 40 giorni) non diminuiscono. Inoltre, sia la valutazione delle proprietà antibatteriche (contro Staphylococcus aureus) che la bioattività hanno dimostrato un comportamento comparabile al ben noto vetro bioattivo 45S5, utilizzato come riferimento in questa tesi. Inoltre, è stato riscontrato che questo composito sperimentale presenta una bassa citotossicità nei confronti delle cellule staminali umane della polpa dentale (HDPSCs).
Bibliografia
[1] Lidia Fanfoni, Eleonora Marsich, Gianluca Turco, Lorenzo Breschi, and Milena Cadenaro. Development of di-methacrylate quaternary ammonium monomers with antibacterial activity. Acta Biomaterialia, 129:138–147, 2021.
[2] Devis Bellucci and Valeria Cannillo. A novel bioactive glass containing strontium and magnesium with ultra-high crystallization temperature. Materials Letters, 213:67–70, 2018.In this PhD thesis, we investigated different strategies to improve the durability of dental restorations. Indeed, despite all the advances in conservative dentistry in recent years, resin-based composites continue to have a high failure rate. One of the main reasons is the development of bacterial microleakage along the margins of restorations and, as a result, the formation of recurrent secondary caries.
In particular, this work can be divided into two main sections: (i) the development and the characterization of adhesives containing antibacterial compounds; (ii) the development and the characterization of resin-based dental composites containing different fillers in order to improve their performances.
In the first part of this thesis, four polymerizable antibacterial di-methacrylate bis-quaternary ammonium monomers (bis-QAMs; namely DDE, DDPyMMA, DDMAPMA and DDM), developed by Fanfoni et al. [1], were selected to attribute antimicrobial features to two different commercial bonding agent, ScotchBond Multipurpose and Scotchbond Universal, 3 steps etch-and-rinse and universal self-etch adhesive, respectively. For eventual clinical use, it is necessary that the addition of these molecules does not reduce the bond strength of the adhesive, also in the long term, and especially that the antibacterial activity is preserved after polymerization. The results of the microtensile bond strength (μTBS), both at time 0 and after in vitro thermo-mechanical aging (simulating 5 years of clinical service), and in vitro antibacterial assessment (towards Streptococcus mutans) have shown that Scotchbond Multipurpose adhesive system is more suitable for the incorporation of these molecules, in particular DDMAPMA can therefore be identified as the best antibacterial monomer, that does not affect mechanical and surface properties.
The second part of this project focused on the development and characterization of nano-reinforced dental composite materials through the incorporation of nanometer-sized hydroxyapatite (nHAp) as a filler, which exhibits antibacterial and remineralization features due to the presence of a lab-made bioactive glass (BGMS10), synthetized by Bellucci et al [2]. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis of the filler powders, HAp and BGMS10, confirmed the presence of nanoscopic particles for both fillers. Mechanical characterization showed that the experimental composites made with different resin/filler ratios (R2/HAp-BGMS10) did not have adequate flexural strength and Vickers microhardness values for their use. However, it is interesting to note that the hardness values of the experimental composites under the conditions simulating the oral environment (immersion
in distilled water, at 37°C for a total of 40 days) do not decrease. Moreover, both the assessment of antibacterial properties (against Staphylococcus aureus) and bioactivity demonstrated comparable behaviour to the well-known bioactive glass 45S5, used as a reference in this thesis. In addition, this experimental composite has been found to have low cytotoxicity towards Human Dental Pulp Stem Cells (HDPSCs).
Bibliography
[1] Lidia Fanfoni, Eleonora Marsich, Gianluca Turco, Lorenzo Breschi, and Milena Cadenaro. Development of di-methacrylate quaternary ammonium monomers with antibacterial activity. Acta Biomaterialia, 129:138–147, 2021.
[2] Devis Bellucci and Valeria Cannillo. A novel bioactive glass containing strontium and magnesium with ultra-high crystallization temperature. Materials Letters, 213:67–70, 2018
