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Anti-tumor activity of an arene ruthenium complex on a model of basal-like breast cancer
No full textBackground\ud
An arene ruthenium(II) complex containing neutral ligands and monoanionic nitrogen donators, has been prepared. The solid-state of the complex is an organometallic structure of half-sandwich (Arene)Ruthenium. The antiproliferative properties of this new ruthenium complex of general\ud
formula [Ru(cym)(L2)Cl]Cl, here called UNICAM1, was assessed by in vitro screening assays and in vivo mouse treatment against inoculation of A17 breast carcinoma triple negative cell line model. From our in-vitro result, it was found that the Ru-complexes exhibit lower antiproliferative activity against different human malignant cancer cells while clearly shown an ability to block cells migration and seems to be characterized by a low toxicity. This study regards the use of this Ru-complex prior characterized chemical and biochemical properties and now as a possible chemotherapeutic agent in a FVB mice model, of breast cancer.\ud
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Results\ud
We observed a significant decrease of tumor growth and a noble clearance from the organism. In addition UNICAM 1 shown less side effects to the host during treatment compared to those of other chemotherapeutic metallodrugs.\ud
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Conclusions\ud
Recent studies have proven that metal-containing compounds have powerful therapeutic effects against malignancy, even though these kind of complexes has not yet been thoroughly explored. Anyway, there are uncertainties with respect to the molecular mechanisms of transition metal compounds, therefore this field will retain a high level of research interest
Novel polymeric delivery systems for pharmaceutical and biomedical applications: from synthesis to in vivo feasibility studies
No full textA polymer is a molecule with high molecular weight constituted by identical or different repeating units (monomers) hold together as a chain by covalent bonds. Nucleic acids, polysaccharides and proteins are biological macromolecules essential for living organism with inner biocompatibility and essential biological activity for health. The biomedical and pharmaceutical applications of natural polymers face some limitations associated to difficult isolation and purification processes connected to the risk of immunological reactions once applied in the human body. The design of synthetic polymers takes inspiration from the main features of natural polymers, with the final goal to overcome their limitations and meet the therapeutic medical needs of patients. The combination of natural and synthetic polymers results in biomaterials with unique and complementary characteristics. The main goal of the present thesis is the development of new biomaterials composed of hybrid and synthetic polymers formulated as hydrogels and nanoparticles for application in drug delivery, tissue engineering, and brain targeting. The central theme of this thesis is presented in Chapter 2. Temperature responsive polymers belong to the class of smart polymers, that, in aqueous solutions, lead to the formation of stimuli responsive hydrogels. For biomedical and pharmaceutical applications, hydrogels must satisfy precise properties that are explained in this section. The chapter mainly focuses on the use of hydrogels for protein release, the ways proteins can be loaded and subsequently delivered in a controlled way from the gel network are explained. The application of hydrogels in tissue engineering is presented and deeply investigated in the following Chapter 3, with particular emphasis on the most recent applications in cartilage repair. After a brief presentation of natural and synthetic hydrogels, the discussion converges on the use of gel networks for the delivery of bioactive molecules such as growth factors mostly involved as signaling and stimulating molecules for cells proliferation, growth and differentiation. Growth factors are rapidly degraded in physiological conditions, being therefore unable to reach the injury site and to unroll their work. The encapsulation into polymeric scaffolds is an efficacious approach to overcome these disadvantages and provide an in-situ release of bioactive proteins. Other strategies for cartilage restoration regards the encapsulation of genetic material encoding for growth factors and the enclosure of platelet rich plasma (PRP) into the hydrogel scaffold.\ud
Chapter 4 introduces the principal biomaterial of this thesis. The aim of the work is to develop a fast-gelling hydrogels composed of a central hydrophilic block of poly ethylene glycol (PEG) flanked by two thermosensitive chains of poly(hydroxypropyl methacrylamide) (p(HPMAm-lac)) derivatized with vinyl groups and cross-linked, by Michael addition with thiolated hyaluronic acid (HA-SH) in a vinyl sulfone- thiol groups ratio of 1:1. Vinyl sulfonated triblock copolymers were highly reactive towards thiol groups giving rise to hydrogels with rapid gelation time and with complete conversion of vinyl sulfone groups. The hydrogels showed increasing G’ values, decreasing gelation temperature (considered as temperature at which G’=G’’), greater swelling and faster degradation kinetics at decreasing thiolation degree of hyaluronic acid. Cells viability, evaluated by MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] assay for 21 days on mouse bone marrow stromal cell (BMSCs) and NIH 3T3 mouse embryonic fibroblasts, showed that cells viability was preserved, and cells maintained their shape for the considered timescale.\ud
Chapter 5 reports on the in vivo biocompatibility study of the tandem cross-linked vinyl sulfone bearing p(HPMA-lac)-PEG-p(HPMA-lac) based hydrogel when injected into Balb/c mice. The hydrogel was easily injected both intramuscularly and subcutaneously and immediately cross-linked in a stable network at the site of administration, as confirmed by ultranosography monitoring. Bone marrow cells of mice treated with hydrogels, after been cultured in medium, showed an important decrease of pro-inflammatory cytokines and chemokines. The decrease is time–dependent, possibly due to the anti-inflammatory effect of hyaluronic acid released during the degradation of the hydrogel. It was concluded that the presented cross-linked hydrogel was a good candidate for tissue engineering applications and for drug delivery.\ud
The feasibility of the application of the vinyl sulfone bearing p(HPMA-lac)-PEG-p(HPMA-lac) based hydrogels in articular cartilage defects is the topic of Chapter 6, where the hydrogel was loaded with platelet rich plasma extracted from equine blood samples. In vitro studies and rheological analysis showed that the hydrogel provided a protective and strong network and increased the mechanical strength of platelet derived fibrin gel. The release studies focused on PDGF-BB and TGF-β1 and is an ongoing work, as well as the viability and proliferation of equine mesenchymal stem cells.\ud
Chapter 7 presents a thermosensitive triblock copolymer of p(HPMA-lac)-PEG-p(HPMA-lac) partly functionalized with methacrylic, acrylic and vinyl sulfone groups and cross-linked with thiolated hyaluronic acid (HA-SH) to form in situ jellying hydrogel. The controlled release of the glycopeptide vancomycin in phosphate buffer (PBS buffer, 150 mM, pH 7.4) at 37 °C was achieved for at least 5 days. Vancomycin, released from hydrogels, was tested for its antimicrobial activity on a gram positive bacterium, Staphylococcus Aureus, whose growth was inhibited by released vancomycin to the same extent vancomycin positive control solutions. Hydrogels with higher amount of hyaluronic acid released vancomycin with slower rates compared to hydrogels with lower polysaccharide content. An ionic interaction between the positive charged vancomycin and the negative hyaluronic acid was postulated and demonstrated. This hypothesis was confirmed by release studies in borate buffered saline (BBS buffer, 10 mM, pH 8.5) at 37°C, where the vancomycin is negative charged and was diffusionally and more rapidly released as compared to hydrogels at pH 7.4. Moreover, it was found that the encapsulation into hydrogel networks prevented vancomycin deamidation. The developed hydrogel system proved efficacious as a potential antibacterial depot to prevent orthopaedic implant associated infections.\ud
The topic of stimuli sensitive polymers inspired the research described in Chapter 8, where a novel dual responsive triblock copolymer system, sensitive to themperature and controllably degradable at acidic pH, composed of a central chain of polyethylene glycol (PEG) flanked by two identical chains with pendent cyclic ortho ester groups, was developed. The side chains give the acid sensitive behavior to the polymer while, the copolymerization with PEG middle block resulted in thermosensitive gel forming polymers. Several triblock copolymers with different molecular weight were prepared and formulated as physical hydrogel networks held together by secondary forces (mainly hydrophobic interactions). The molecular weights of the polymers and the amount of polymers into the hydrogels directly influenced the gelation times of the hydrogels. The perspective is to evaluate the swelling behavior of the hydrogels at different pHs and to stabilize the polymer network by the use of chemical cross-links to ensure higher mechanical strength. One examples of chemical cross-link is the Michael addition reaction among acrylic, methacrylic or vinyl sulfone groups and thiolated ones. In-vitro viability on mesenchimal cells will be investigated to assure the lack of toxicity and the potential feasibility of the hydrogels for in-vivo applications. Recently, several studies reported on nanohydrogels systems for biomedical applications. Nanohydrogels are hydrogel based nanoparticles in the nanometer scale from tens to hundreds of nanometers that combine the advantages of hydrogels and nanoparticles for drug formulation and delivery, which include controllable drug release, high stability in physiological media, distinct responsiveness to environmental factors such as pH and temperature, high cellular uptake due to the endocytosis mechanisms, long half-life in circulation by appropriate surface modification and drug targeting by conjugation of ligand onto the surface of hydrogel nanoparticles. Future development of the poly ortho esters-PEG- poly ortho esters triblock copolymers as nanohydrogel systems is an attractive perspective.\ud
In Chapter 9 a new adenosine conjugated polylactic-co-glycolic acid-polyethylene glycol PLGA-PEG block copolymer formulated in the form of solid nanoparticle for brain targeting was investigated and developed. The nanoparticle core consisted of hydrophobic PLGA shielded by an external corona of PEG surface decorated with adenosine, chosen as model ligand to specifically target nucleoside transporters present on the blood brain barrier (BBB). Adenosine was linked to the PEG via its amino group in position 6’ of the adenine. Homogenous polymer distribution, particle size of 200 nm and spherical shape were assessed. Rhodamine 6G, a highly fluorescent dye was encapsulated into the polymeric nanoparticle and used for in vivo studies to determine circulation time and brain uptake of the nanoparticles upon intravenous administration in mice. Release studies from nanoparticles are ongoing. In vitro stability, cell viability, haemolysis and platelet aggregation of nanoparticles will be tested.\ud
Further development of this research topic will be the development of PLGA-PEG-Adenosine copolymers conjugated via the hydroxyl group in position 5’ of adenosine ribose, which, according to structure activity relationship studies (SAR) is not involved in the binding of adenosine with transporters
“Contratti di trasferimento di tecnologia. L’ipotesi del know-how”
No full textLa tesi si propone di sviluppare il tema dei contratti di trasferimento di tecnologia alla luce di quanto risulta dall'attenta disamina della prassi internazionale e della normativa comunitaria in materia. Dopo aver analizzato il significato del termine «tecnologia» da un punto di vista storico-semantico e ripercorso le esperienze degli accordi TRIPs e del Codice di condotta dell'UNCTAD, il lavoro si dedica ad un esame accurato della normativa comunitaria in tema di tecnologia con specifico riferimento al recentissimo regolamento CE 316 del 2014 che introduce il concetto di "diritti tecnologici". Tra questi ultimi e' riconosciuta una posizione di chiara preminenza al c.d. "know-how" all'analisi del quale lo studio dedica ampio spazio allo scopo di delimitare i confini di quella che ancor oggi appare essere una delle categorie piu' controverse, specie in considerazione del quasi totale silenzio del legislatore e della scarsa coerenza di dottrina e giurisprudenza in materia. Superando la tradizionale bipartizione tra know-how in senso stretto e in senso lato e il diverso approccio basato sulla natura, tecnica o commerciale, delle conoscenze definite come know-how, il lavoro si dedica all'esame dei possibili elementi essenziali caratterizzanti la figura in questione. Ampio spazio e' dedicato dunque all'analisi del carattere della segretezza inteso non come elemento indispensabile affinche' le conoscenze oggetto di scambio possano utilmente essere definite know-how, bensi' come potenziale termometro del valore economico della conoscenza in caso di controversia relativa alla sua circolazione. La ricerca si propone quindi di esaminare il contratto di cessione di know-how nella sua forma piu' semplice allo scopo di procedere ad una corretta qualificazione di quest'ultimo utilizzando, laddove possibile, i tipi contrattuali previsti dal legislatore. In conclusione la ricerca si concentra sull'ipotesi di trasferimento di know-how in ambito internazionale, sull'applicabilita' al medesimo delle principali norme convenzionali ed all'analisi della normativa vigente in tema di diritto internazionale privato.\ud
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Abstract\ud
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The thesis aims to develop the theme of the technology transfer contracts taking into account the results of an accurate examination of International practices and EU legislation. After analysing the meaning of the term 'Technology' from an historical and semantic point of view, and traced the experiences of the TRIPs Agreements and the UNCTAD Code of Conduct, the work contains a deep analysis of the EU legislation in the field of technology with specific reference to the recent EC Regulation 316 of 2014 which introduces the concept of "technology rights". Among the latter a position of prominence is given to "Know-how" to the analysis of which the thesis gives extensive attention in order to demarcate the boundaries of what still appears to be one of the most controversial categories, especially in the almost total silence of the legislator and the lack of consistency of doctrine and courts decisions. Overcoming the traditional division between know-how in the "narrow sense" and in a "broad sense" and the different approach based on the nature, technical or commercial, of the knowledge defined as know-how, the study examines the possible essential elements characterizing the figure in question. Considerable space is given to the analysis of the character of "secrecy" here considered not essential to make the knowledge usefully defined as know-how, but as a thermometer of the potential economic value of knowledge in the event of a dispute concerning its circulation. The research is therefore aimed at examining the contract for the transfer of know-how in its simplest form in order to make a correct classification of the latter using, wherever possible, contract types provided by the legislator. In conclusion, the research focuses on the hypothesis of international transfer of know-how, the applicability of the most important conventional treaties and the analysis of the current legislation in the field of private international law
Phosphodiesterase 7(PDE7) inhibitors: a new target to treat drug addiction\ud
No full textDrug addiction not only causes addicts health damage, but also leads serious social, economic and public health problems, which threaten our harmonious society. The neurobiological mechanism of drug addiction has not been fully elucidated that is still lack of ideal treatment and\ud
intervention models. Especially, relapse is a worldwide problem, the high relapse rate after detoxification treatment more than 95%. The nucleotide phosphodiesterase (PDE) type 7 family includes two members, PDE7A and PDE7B, which are cyclic-AMP-specific PDEs expressed in brain\ud
dopaminergic regions linked to addiction, such as the nucleus accumbens (NAc) and ventral tegmental area (VTA). Here we assessed the role of PDE7 in addiction by evaluating selective PDE7 inhibitors (PDE7i) Compound A and Compound B in rat models of durg self-administration and relapse to drug seeking by behavior test. Our results showed that PDE7 inhibition by Compound A or Compound B significantly reduced fixed-ratio 3 and progressive ratio nicotine self-administration. In preclinical model of relapse we found that Compound A and Compound B also attenuated cue- and yohimbine-induced reinstatement of nicotine seeking. In rats implanted bilaterally with intracranial cannulas aimed at the VTA, we found that site specific injection of Compound A or Compound B into this brain area significantly reduced nicotine self-administration under both FR-3 and PR schedule of reinforcement suggesting a role of corticomesolimbic dapaminergic circuitries in PDE7i effects. In cocaine addiction experiments, the results showed that PDE7 inhibitor Compound B (low dose, intermediate dose and high dose) significantly reduced cue-induced relapse to cocaine seeking. The reinstatement experiments showed that PDE7 inhibitor exhibited significant effects in preventing stress-induced relapse to cocaine seeking behavior at the doses tested (low dose and high dose). The same results\ud
were found in heroin addiction test. The PDE7 inhibitor Compound A (intermediate dose and high dose) significantly reduced heroin-seeking behavior after extinction. The reinstatement experiments showed that PDE7 inhibitor Compound A exhibited significant effects in preventing\ud
cue-induced relapse to heroin seeking behavior at the doses tested (low dose, intermediate dose and high dose). Further, PDE7 inhibitor (intermediate dose and high dose) significantly reduced alcohol self-administration. The reinstatement experiments showed that PDE7 inhibitor exhibited significant effects in preventing stress- and cue-induced relapse to alcohol seeking behavior. These findings suggest that PDE7 could be a novel therapeutic target for drug addiction
Design, synthesis and biological evaluation of novel inhibitors of key enzymes in c-di-GMP metabolism as potential antibiofilm drugs
No full textBacterial biofilm is responsible for numerous chronic infections, which are characterized by persisting inflammation and tissue damage. Many of these infections cannot be resolved, as bacteria in biofilms are resistant to the host’s immune defenses, antibiotic therapy and disinfectant chemicals. 3',5'-Cyclic diguanylic acid (c-di-GMP) is a widely conserved second-messenger signal that regulates a wide range of functions including motility, synthesis of virulence factors, adhesion and biofilm formation. In particular, high levels of intracellular cyclic di-GMP promote biofilm formation and sessility, whereas low levels induce biofilm dispersion and motility. Since the pathways involved in c-di-GMP signaling are not present in mammalians, they represent attractive targets for the development of anti-virulence drugs. Synthesis of c-di-GMP occurs via diguanylate cyclase (DGC) enzymes, encoding GGDEF domains, while degradation of c-di-GMP occurs via phosphodiesterase (PDE) enzymes, encoding either an EAL or a HD-GYP domain. The identification of compounds reducing c-di-GMP levels in bacteria would allow the development of new antibiofilm drugs.\ud
In my PhD thesis, an array of c-di-GMP-based molecules has been synthesized and tested on both DGC and PDE enzymes, in particular RocR (PDE), WspR and YfiN (DGCs) from P. aeruginosa, and PleD (DGC) from C. crescentus. Three series of compounds have been rationally designed as linear c-di-GMP analogues using a molecular simplification strategy and a click chemistry method. In particular, a unique scaffold was identified, where two guanine bases and their derivatives were directly linked by a triazole moiety. The most potent inhibitor of the series resulted to inhibit PleD (89%, at 100 μM inhibitor) and RocR (59%, at 100 of μM inhibitor) with IC50 values of 17.5 +- 1.1 μM and 66.3 +- 1.3 μM, respectively. The novel inhibitors possess a number of properties that are attractive from a drug development point of view, compared with other c-di-GMP analogues. They are low-molecular-weight compounds, stable and easily synthesizable. More importantly, this study allowed us to identify the minimal structural determinants required for specifically targeting the I-site of DGCs. Although none of these compounds were able to inhibit biofilm formation in vivo, they could become potential tools for mechanicistic biochemical studies, in particular for hybrid protein which contains both the GGDEF and EAL domains.\ud
During my research experience at the Institute of Organic Chemistry at the Department of Chemistry of University of Hamburg (Germany), I was involved in a project comprising the stereoselective synthesis of new iso-carbocyclic nucleoside analogues for the further study of their bioactivity in the context of anti-HIV and anti-HCV inhibition. It is widely known that carbocyclic nucleoside analogues possess important biological advantages compared to natural nucleosides and they have received much attention as potential antiviral drugs over the last few decades. Carbovir, abacavir and carba-dT are examples of these efforts, resulting in efficient inhibitors of HIV’s reverse transcriptase. A convergent approach was used for the synthesis, offering the formation of a variety of nucleoside analogues by the direct coupling of a chiral cyclopentanol with purine and pyrimidine nucleobases. These compounds are currently under investigation as potential antiviral drugs
Decoherence in Quantum Networks
No full textThe title of the present dissertation Decoherence in Quantum Network sounds very general and all-inclusive. Indeed it embraces two topics (decoherence and quantum network) from the area of Quantum Mechanics each of which is described in all respects by a huge literature developed in the last three decades [...]. Quantum decoherence, as the name lets it mean, is the mechanism that makes a quantum\ud
system loose its coherence properties, and with them the capability of giving rise to interference phenomena or to other interesting quantum effects [...]. The key idea promoted by decoherence is the insight that realistic quantum systems are never isolated, but are immersed in the surrounding environment and interact continuously with it [...]. As an example one may consider a two-level quantum system (i.e. a quantum bit, usually shortened with a terminology from information science to \qubit" ) in contact with a wide environment. Hence, quantum systems are open systems, and continuously interact or exchange information with an external environment whose degrees of freedom are too numerous to be monitored. The resulting correlation between the system and the environment spoils quantum coherence and brings about the transition from a pure quantum state to a mixture of quantum state resulting a classical state. To describe decoherence different kind of\ud
approaches can be used (for example Master equation, random matrix, etc).\ud
A quantum network typically consists of a number of quantum objects (e.g., atoms, ions, quantum dots, cavities, etc.), to be referred to hereafter as the sites or the nodes of the network. They can interact and the interactions (or their correlations) will be usually described by the edges of a graph. Quantum networks can address different information processing tasks. For instance a quantum state\ud
can be transferred from qubit to qubit down a chain solely due to the interactions, that is according to the laws of quantum physics [...]. Quantum networks offer us new opportunities and phenomena as compared to classical networks. An extension to large scale of the idea of a quantum network could lead to a futurible quantum internet [...].\ud
The study of networks has traditionally been the territory of graph theory [...], also with the advent of their quantum versions. Within simple quantum network model information processing is usually described by assuming perfect control of the underlying graph. However, this is not much realistic since randomness is often present and it leads to decoherence effects [...]. In contrast, the conservation of coherence is essential for any quantum information process [...], hence there is a persistent interest in decoherence effects in quantum networks, which motivate us to study models for describing such noisy effects.\ud
We consider a simple model of quantum network, employing qubits (spin-1/2 particles) attached to the nodes of an underlying graph and we study the simplest task, namely information storage (on a single and two qubits), when the\ud
graph randomly changes in time. Actually we randomly add edges to an initially disconnected graph according to the Gilbert model characterized by a weighting parameter ex [...] and in an identically and independent way at each\ud
time step. We find that by increasing ex the dynamics of relevant quantities like fidelity, entropy or concurrence, gradually transforms from damped to damped oscillatory and finally to purely oscillatory. That leads to the paper [see, Information dissipation in random quantum networks, by U. Farooq and S. Mancini, OSID 21(3), 1450004, 2014].\ud
We also study a system composed by pairs of qubits attached to each node of a linear chain, a model that stems from quantum dot arrays. Here we use the approach of evolution with a stochastic Hamiltonian to describe the noisy effects.\ud
We then evaluate the effect of two most common disorders, namely exchange coupling and hyperfine interaction\ud
fluctuations, in adiabatic preparation of ground state in such model. We show that the adiabatic ground state preparation is highly robust against these disorders making the chain a good analog simulator. Moreover, we also study the adiabatic information transfer, using singlet-triplet\ud
states, across the chain. In contrast to ground state preparation the transfer mechanism is highly affected by disorders. This suggested that for communication tasks across such chains adiabatic evolution is not as effective and quantum quenches would be preferable. That leads to the paper [see, Adiabatic many-body state preparation and information transfer in quantum dot arrays, by U. Farooq,\ud
A. Bayat, S. Mancini and S. Bose Phys. Rev. B 91, 134303, 2015].\ud
The present work is organized as follows.\ud
In chapter 1, we shall give a survey of the various types of approach which can be employed to analyse the dynamics of open quantum systems that leads to decoherence effects.\ud
In chapter 2, we shall give a general description about quantum network and its possible applications.\ud
In chapter 3, we shall discuss the problem of quantum state transfer in qubit network and shall give a brief overview of some scheme that enable nearly prefect state transfer.\ud
In chapter 4, we shall discuss singlet-triplet networks, that is networks having on each site a pair of (generally entangled) qubit. Then within this framework we propose a model stemming from quantum dot array. There we shall address the problem of ground state preparation and state transfer. Finally we shall describe the inherent entanglement of the ground state of strongly correlated systems can be exploited for both classical and quantum communications.\ud
In chapter 5, we shall propose a decoherence model for qubit networks based on edges representing XY interactions randomly added to a disconnected graph accordingly to a suitable probability distribution. In this way we shall describe dissipation of information initially localize in single or two qubits all over the network.\ud
In chapter 6 we shall model the noisy effects in the quantum dot array introduced in chapter 4 and investigate their consequences on the preparation of ground state and quantum state transfer mechanism.\ud
Finally we shall draw conclusions
New ecosustainable cement from ceramic waste
No full textThe aim of the work is to reuse ceramic waste, in order to allow the production of Pozzolanic cement also in the regions where natural pozzolan or artificial pozzolan, like fly ash, are not available. This possibility, beyond the higher durability of the concrete in the environment in which the pozzolanic properties are required, allows a saving of high percentages of clinker in cement production, reducing in a proportional way the needs of raw material from quarrying and the issues related to the waste disposal of Construction & Demolition waste (CDW). All these issues are of fundamental interest for European research and environmental policy, as well as finding direct application in the industry of building and constructions.\ud
This research investigates the possibility to use ceramic waste in the preparation of cement or in concretes as Supplementary Cementitius Material, through the determination of the chemical and mechanical behaviors. The research starts from the sampling of ceramic waste from construction and demolition landfills or from the disposal sites of the ceramic industry. The study of the behavior of these materials was carried out checking the match of the required chemical properties of the each materials for its eligibility as pozzolanic materials, or addition, in accordance to European and American standards. After that, several experimental Pozzolanic cements were produced in laboratory, using the ceramic wastes in a variety of different percentages, in replacement of the Portland cement type I 52,5 R, containing over 95 % clinker Portland.\ud
The new experimental Pozzolanic cements were characterized about chemical and mechanical properties in comparison to 4 reference commercial cements, which are produced with the same kind of clinker Portland in the same factory, the mentioned Portland cement type I 52,5 R, also used as in the production of all experimental Pozzolanic cements, a Pozzolanic cement type IV/A (P) 42,5R, a Pozzolanic cement type IV/B (P) 32,5 R and a Composite Portland cement type II/B-LL 32,5 R.\ud
The new experimental Pozzolanic cements were also tested in the production of concrete, in order to evaluate the actual mechanical performances in the building works, from which depends dosage and convenience of the cement and the possibility to produce high strength classes of concrete.\ud
Over 30 different experimental Pozzolanic cements, were produced and tested about the pozzolanicity and in concrete production, each at several different water/cement ratios, obtaining an excellent mechanical strength, especially in the production of concrete with low water/cement ratio and high mechanical performance.\ud
The results indicate, first of all, the possibilities to produce Pozzolanic cement through different types of ceramic wastes. The waste from bricks and tiles permits to assure the necessary high level of pozzolanicity at 8 day for its classification as Sulphate Resistant Pozzolanic cement in accordance to EN 197-1: 2011. This kind of ceramic waste shows behavior and performances very similar to the common natural pozzolans usually quarried and used in central Italy for cement production. The second kind of ceramic waste, from porcelain stoneware production process, named hard ceramic, thanks to the high pozzolanic activity, assures the possibility to produce Sulphate Resistant Pozzolanic cements in accordance to European Norm, with very little contents of ceramic waste and obtaining mechanical performances in the standard mortar similar or better than those of the pure Portland cement type I 52,5 R. Also, the possibility of using ceramic waste in the cement production, depending on the type of cement required, can reach the maximum quantity of pozzolanic material allowed in cement in accordance with the EU norms.\ud
Moreover, the results in concrete at low water/cement ratio indicate very interesting opportunities for using these cements for the production of very high performance concretes, showing the possibilities to obtain mechanical strengths at 28 days of maturation higher than those of the commercialized Portland cements type I, having the maximum strength class 52,5 R. The higher increasing of mechanical strength of the concrete made with Pozzolanic cement, not only those containing ceramic waste [...] but also with the natural pozzolans used as reference, highlights the benefit of the use of Pozzolanic cements, which appear to be less advantageous just from the point of view of the standard mortar, as well as in concretes with w/c ratio higher than 0.5. To the better mechanical performance in concrete at low w/c ratio it must be added the lower heat of hydration due to the reduction of the clinker Portland content and the higher durability.\ud
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This research work is described in 5 chapters, with the following main contents:\ud
Chapter 1- Introduction - A short history of the use of pozzolan and ceramic waste in the production of water resistant concrete. In the chapter are also indicated modern applications, standards on the cement production and environmental implication of the use of ceramic waste in the cement.\ud
Chapter 2 Materials e methods - The materials involved in the experimentation (raw materials, ceramic wastes, commercial cements, experimental cement mixes) are reported and described in this chapter, together with methods and tests applied in the experimentation. Even if the great part of the used tests are in accordance to Standard norms, they are described in order to indicate, for each of them, the actual meanings of the results and the difference between results of test having apparently similar scope.\ud
Chapter 3 Results - The chapter reports and describes the results of the characterization of each ceramic waste, together with the results of the different tests used to characterize the properties of the new experimental cements, in comparison to 4 reference commercial cements. Particular attention was taken in the evaluation of the behavior of the new cement in concrete.\ud
Chapter 4 Discussion - In this chapter, the behavior of different kinds of ceramic waste and the applicability for the cement production are displayed, as a result of the very high chemical and mechanical potential performances obtained. The interesting properties of a new pozzolanic cement are evidenced and compared to those of the common Portland cement and Pozzolanic cement. The data are discussed also in terms of their impact on the environmental issues related to the cement industry.\ud
Chapter 5 Conclusions – In this chapter a summary of the most important results obtained in the study is reported, with a discussion on the applications of the experimental cements produced and the industrial implications. The possible classification of 2 new ecosustainable pozzolanic cements produced through two different kinds of ceramic waste are reported, in accordance to the European Norm about cement production EN 197-1:2011
Novel Silver Complexes as Additives for Innovative Composite Materials with Permanent Antimicrobial Activity
No full textIn summary, most of the experimental work of my PhD thesis has been devoted to develop novel silver complexes with suitable physico-chemical properties for their employment as additives in antimicrobial composite materials with persistent activity. Among the most relevant results, the silver coordination polymers seem to be the most effective for their application as additives, due to their high and broad spectrum antimicrobial activity. Such activity is persistent in time, likely because of a contact mechanism of toxicity against bacteria, due to exposed silver centers within the polynuclear chain, which are able to attract the negatively charged cell membranes of bacteria altering their membrane potential and provoking their death. In any case, the release of silver ions from the composite material seems very limited or absent, thanks to the insolubility of such silver coordination polymers in almost all solvents and water, an essential feature for their application as additives for plastics. Future developments of this research will be directed to optimize the homogeneity of the composites’ surfaces by changing the substituents in the HQR proligands with the aim of increasing their hydrophobicity and solubility in the polymeric matrices