Dipartimento di Fisica - Tesi di Dottorato

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Questa collezione raccoglie le Tesi di Dottorato afferenti al Dipartimento di Fisica dell'Università della Calabria.

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Author: search.filters.author.Versace, CarloSubject: search.filters.subject.Fisica applicata

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Now showing 1 - 6 of 6
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    Atomic forcemicroscopy of corneal biomechanics
    (2014-11-28) Labate, Cristina; Bartolino, Roberto; Versace, Carlo; Barberi, Riccardo; De Santo, Maria P.
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    New methods for characterization and dating in material of cultural heritage
    (2014-11-03) Bosco, Stefania; Versace, Carlo; Chidichimo, Giuseppe
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    Optical systems for diagnostics: Near-Infrared Imaging technique for detection of dental demineralisation
    (2012-11-30) Salsone, Silvia; Versace, Carlo; Lombardo, Giuseppe; Zakian, Christian; Bartolino, Roberto
    In dentistry, a correct detection of caries severity is still a challenging descision-making task that crucially a ects the choice for the best treatment plan. The challenge is to nd both the most objective parameters to detect caries at di erent stages (from an early reversibile stage to a severe one) and the most reliable method(s) that should be used to distinguish these stages. Currently, methods used in clinics are visual inspection, aided with light probe and pick inspection tools, and radiography. The main issue rising by the use of these methods is that both of them are subjective, with possibility for intra- and inter-examiner variability. For this reason, radiography needs an extreme care of interpretation especially when assessing occlusal caries. Visual methods, instead, are a ected by confounding factors, such as stain or uorosis, a ecting the accurate assessment of early caries lesions. Radiography, moreover, should be performed with care considering that the emission of ionising radiation may cause malignant change in tissues, especially for young age patients and are counter-indicated during pregnancy. They are also inadequate for the detection of initial caries and to locate the lesions looking at the superimposition of the tooth along its buccal-lingual axis. The aim of this study was to overcome the limits of the current detection techniques, o ering a non-invasive, objective method for the detection of caries at any stage of the demineralisation process. The proposed method measures the near-infrared (NIR) re ectance response of the tooth at three speci c wavelengths. It is then possible to investigate properties of the sample at the surface and in depth and get an image that maps the lesions on the occlusal view of the sample when combining these wavelengths. Due to the properties of the NIR light, this method is non-invasive, non-contact and allows for detection both at the enamel and at the dentine level. The NIR method o ers objective supporting information to quantify and detect dental caries and is especially suitable for areas a ected by confounding factors, such as stain. The objective of the study was to design and implement a NIR multispetral imaging system, developing e cient image analysis algorithms. In order to prove this objective, an in vitro validation of the technique against gold standard histology was performed together with a comparison to other detection methods - International Caries Detection and Assessment System (ICDAS - clinical visual inspection), bre optic transillumination method (FOTI - visual inspection with light probe), radiography and Quantitative Light-induced Fluorescence method (QLF), used in clinics or in research. A total of 112 teeh, molars and premolars, with di erent lesion severities were used for this study. Histologcal sections were obtained to con rm the lesion severities and used as a gold standard to compare the sensitivity and speci cty among techniques. Visual inspection methods recorded the highest values of sensitivity (ICDAS: >99%, FOTI: 93%) and speci city to dental caries (FOTI: >99%, ICDAS: 90%). However, these methods could have been highly facilitated by the in-vitro viewing of the samples. Sensitivity to dental caries was higher for NIR (91%) than for QLF (88%) and radiography (63%) while speci city was higher for radiography (81%) than for NIR (73%) and QLF (63%). The results from this study suggest that the NIR method has the ability to detect dental caries when other methods fail, providing an alternative to assist in the decision-making process with the further advantage of removing the confounding e ect of stain. This method can enhance patient communication and o ers an objective and safe alternative to ionising radiation methods.
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    Micro raman spectroscopic investigations on soft matter systems
    (2012-12-04) Fasanella, Angela; Versace, Carlo; Bertolini, Roberto; Cazzanelli, Enzo
    University of Calabria
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    Properties of biomolecules at the interfaces: studies and characterization of chromonic mesogens, from the basis to applications
    (2013-11-28) Tone, Caterina; Bartolino, Roberto; Versace, Carlo; Ciuchi, Federica
    The study of the interaction between molecules, in particular biological molecules and liquid crystals (LC), has experienced a huge growth in the recent years because of the development in devices engineering applied not only in photonics but also in the biomedical eld. In order to design more e cient LC devices, it is rst necessary to understand the behavior and properties of newly-synthesized liquid crystals and to garner a more indepth understanding of currently-existing LCs in order to answer pending questions about them. The aim of this thesis work, is to better understand the interactions involved at the interface between liquid crystals and other materials, whatever is their nature, i.e. polymeric or biological. We started studying the e ect of di erent con ning surfaces on the alignment of a special class of lyotropic liquid crystals, called \chromonics", which, in addition of LC properties, are biocompatible. Di erently from the most common liquid crystals, i.e. thermotropic LC, the mesogens that constitute the chromonic LC phases are not amphiphilic, but they are \plan-like" aromatic compound. This class of molecules embraces not only dyes and drugs, but also DNA and its bases. Using the knowledge acquired with chromonic mesogen, we tried to understand a more complicate system, such as the phenomena involved at the biomolecules decorated-liquid crystals lms interfaces. More speci cally, it is possible to divide the work in two macro-parts. The rst part concerns the alignment of a chromonic molecule, \disodium cromoglycate" (DSCG). The study of chromonic LC behaviour in con ned geometries and its physical properties, could be a model for more complex biological assemblies. Hence, we demonstrated the role of alignment layer's surface energy in the alignment of nematic phase of DSCG, achieving both alignments and for the rst time, a stable-in-time homeotropic anchoring of this LC solution. With the knowledge acquired from DSCG, we were able to align also DNA bases liquid crystal solutions. In particular, guanosine monophosphate in pre-cholesteric and cholesteric liquid crystals phases were perfectly aligned homeotropically without means of external elds, as was done until now, and partially planar aligned. Moreover, we observed that if ionic and/or silver doped solutions are added to the LC guanosine phases, it is possible to control the pitch of the cholesteric phase, modifying the helix structure. Instead, varying the nature of the con ning surfaces, in such conditions, it is possible to obtain guanosine vesicles. Other studies have been carried out on new chromonic complexes, synthesized at Chemistry Department of UNICAL, with possible application as anticancer drugs. A complete characterization of these compounds were done (XRD, phase diagrams, etc) and also for these compounds, we developed a\route"to drive the alignment, particularly important for future application in biophotonic devices. The second part of the work is focused on LC based biosensors. From the biotechnological and biomedical applications point of view, the studies on interactions of proteins with lipids are an area of fundamental interest, due to enormous biological importance. In fact, studies on biosensor devices are tremendously increased in recent years, focusing the attention also on nding low cost raw materials with high e ciency: liquid crystals, thanks to their high sensitivity to the external conditions, represent the best candidate. It has been demonstrated that aqueous interface of LC has an instantaneous response when exposed to phospholipids. This is a good base to study the interaction between biomolecules using LC as probe. Starting from the results found in literature, we studied the e ect of phospholipids on protein decoratede-liquid crystal interfaces by means of optical microscopy and FT-IR measurements. The rst technique allowed us to observe the response of decorated LC lm when exposed to phospholipids vesicles, while the second, gave us insight on conformational changes involved in secondary structure of the protein in function of the time of interaction between protein and LC, and the pH of the surrounding environment. The results obtained show a new methods to report speci c binding of vesicles on protein decorated interfaces.
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    Nanostructured Soft Matter: Mirror-less Lase
    (2008) Matranga, Mario Ariosto; Versace, Carlo; Barberi, Riccardo