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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Electrochemical imaging of living cell metabolism: investigation on Warburg effect in cancer

Soldà, Alice <1986> January 1900 (has links)
Cancer is one of the principal causes of death in the world; almost 8.2 million of deaths were counted in 2012. Emerging evidences indicate that most of the tumors have an increased glycolytic rate and a detriment of oxidative phosphorylation to support abnormal cell proliferation; this phenomenon is known as aerobic glycolysis or Warburg effect. This switching toward glycolysis implies that cancer tissues metabolize approximately tenfold more glucose to lactate in a given time and the amount of lactate released from cancer tissues is much greater than from normal ones. In view of these fundamental discoveries alterations of the cellular metabolism should be considered a crucial hallmark of cancer. Therefore, the investigation of the metabolic differences between normal and transformed cells is important in cancer research and it might find clinical applications. The aim of the project was to investigate the cellular metabolic alterations at single cell level, by monitoring glucose and lactate, in order to provide a better insight in cancer research. For this purpose, electrochemical techniques have been applied. Enzyme-based electrode biosensors for lactate and glucose were –ad hoc- optimized within the project and used as probes for Scanning Electrochemical Microscopy (SECM). The UME biosensor manufacturing and optimization represented a consistent part of the work and a full description of the sensor preparation protocols and of the characterization methods employed is reported. This set-up (SECM used with microbiosensor probes) enabled the non-invasive study of cellular metabolism at single cell level. The knowledge of cancer cell metabolism is required to design more efficient treatment strategies.
42

Electrochemistry of Molecular Systems for New Nanostructured Materials and Bioelectronic Devices

Ussano, Eleonora <1982> January 1900 (has links)
Nanomaterials have a tremendously increasing importance in our daily lives but their world is extremely wide. The main aim of this work is to implement the knowledge about these materials, focusing in particular on some of the nano allotropic forms of Carbon. This precise choice is consequence of their extreme versatility and promising properties for electronic, energetic and biological applications, which can be further improved with doping or functionalization. In the first part of my work I introduced nanotechnology and nanomaterials, highlighting their importance, recent developments and applications, trying to focus on the importance of electrochemistry in the study of such a field. Electrochemistry, in fact, through the investigation of fundamental electronic processes can exploit electrical and catalytic processes of nanomaterials and become an interface between nano and macroscopic world. The second chapter of this thesis is dedicated to the investigation of a new synthetic pathway for bottom up nano-Graphene production, using polyaromatic hydrocarbons precursors. The chemical and morphological analysis of the obtained deposits gives encouraging results about the proficient production of Carbon-base nano-assemblies. The third chapter is dedicated to the study and application of nanocarbons for energy production with particular attention to the incoming environmental problem. The objects of my study were Nitrogen-doped Graphene, as an alternative to metal catalysts for Oxygen reduction reaction (ORR), and a Bodipy chromophore coupled with a Fullerene, as an efficient system for photoelectrochemical conversion. The results obtained until now in the study of Carbon-based nanomaterials represent a good reason to further investigate their behaviour, properties and possible applications and I hope this thesis is a contribution to such a complex topic.
43

Measurement of the t-tbar differential cross section at large top quark transverse momentum in sqrt(8) TeV pp collisions using the ATLAS detector at the LHC

Massa, Lorenzo <1988> 23 March 2016 (has links)
The top quark is the heaviest particle in Standard Model. When it is produced with a large Lorentz boost, its decay products tend to overlap, making the standard reconstruction techniques inefficient; large R jet substructure analysis techniques allow to increase the detection efficiency for these events. Various differential cross section measurements of boosted t-tbar from pp collisions with sqrt(s)=8 TeV are presented: with respect to the mass, to the transverse momentum and the pseudorapidity of the t-tbar system. The results here have been obtained using a sample of 20 fb^-1, recorded by ATLAS during 2012. The events are selected with a cut-based approach in the single lepton plus jets decay channel, where the lepton can be either an electron or a muon. The final background-subtracted distributions are corrected for the distortion introduced by the detector and selection effects using unfolding methods. The measurements are dominated by the systematic uncertainties, and are in agreement with the Standard Model, even if it can be seen a general tendency of the theoretical predictions to overestimate the measured cross section for increasing transverse momentum and mass of the t-tbar system.
44

Search for the TTH Production in Multi-Leptonic Final States with the Atlas Detector at LHC

Lasagni Manghi, Federico <1988> 23 March 2016 (has links)
Since the discovery of the Higgs boson in 2012, the aim of the correlated physics analyses moved towards the measurement of its properties to verify the consistence with the Standard Model and to study possible signals of physics Beyond Standard Model. In particular, any discrepancy in the Higgs-SM couplings would point to new physics contributions. The ttH channels is a privileged channel for this pourpose, because it depends on a small number of BSM parameters. In this thesis the analysis of the production of a Higgs boson in association with a top and anti-top quark couple and decay into multi-leptonic final states in ATLAS at LHC is described. The analysis is focused on the channel defined by two light leptons of the same sign and no hadronic tau leptons in both Run I and Run II. The analysis is an essential preparatory step for the 2016 data-taking. After introducing the Higgs boson, LHC and the ATLAS experiment, the results of the Run I analysis are presented, which pose a first limit on the deviation of the cross section from the SM. A large part of the thesis is dedicated to the data-driven estimation of the main background of this channel, fake leptons produced in meson decays, using a technique denominated matrix method. This alternative background estimation is explained and applied to the analysis, producing alternative results. In the last part of the thesis, the first stages of the analysis of the 2015 data is shown, in preparation of the 2016 data-taking.
45

Conformational equilibria, non-bonding interactions and chirality from rotational spectroscopy

Spada, Lorenzo <1983> January 1900 (has links)
The aim of this thesis is to characterize the genuine nature of the non-bonding interactions, such as hydrogen, weak hydrogen and halogen bonding as well as the lone pair•••π interaction, in an environment free from solvent or matrix effects, by using rotational spectroscopy in supersonic expansion. Fluorination and methylation effects, competition between different non-covalent interactions, isomeric preferences are described in the molecular system studied as well as the proton transfer process, the Ubbelohde and the reverse Ubbelohde effects, the internal rotations, and quadrupole couplings which take place. The dissociation energies of the molecular adducts are also estimated and the structural determination of molecules and/or molecular complexes is performed by using isotopologue spectra. Conformational and tautomeric equilibria are investigated for molecules of biological interests, occasionally using the laser ablation technique. Studies have been performed in order to differentiate the enantiomers of chiral molecules, based on opposite phase detection in double quantum coherence experiments.
46

Predictability in Social Science, The statistical mechanics approach.

Seyedi, Seyedalireza <1980> 09 June 2015 (has links)
The subject of this work concerns the study of the immigration phenomenon, with emphasis on the aspects related to the integration of an immigrant population in a hosting one. Aim of this work is to show the forecasting ability of a recent finding where the behavior of integration quantifiers was analyzed and investigated with a mathematical model of statistical physics origins (a generalization of the monomer dimer model). After providing a detailed literature review of the model, we show that not only such a model is able to identify the social mechanism that drives a particular integration process, but it also provides correct forecast. The research reported here proves that the proposed model of integration and its forecast framework are simple and effective tools to reduce uncertainties about how integration phenomena emerge and how they are likely to develop in response to increased migration levels in the future.
47

Structure and dynamics of metal sites in proteins: X-ray Absorption Spectroscopy investigations

Giachini, Lisa <1978> 17 May 2007 (has links)
No description available.
48

Simulation of Smart Materials

Matta, Micaela <1987> January 1900 (has links)
The aim of this thesis is the elucidation of structure-properties relationship of molecular semiconductors for electronic devices. This involves the use of a comprehensive set of simulation techniques, ranging from quantum-mechanical to numerical stochastic methods, and also the development of ad-hoc computational tools. In more detail, the research activity regarded two main topics: the study of electronic properties and structural behaviour of liquid crystalline (LC) materials based on functionalised oligo(p-phenyleneethynylene) (OPE), and the investigation on the electric field effect associated to OFET operation on pentacene thin film stability. In this dissertation, a novel family of substituted OPE liquid crystals with applications in stimuli-responsive materials is presented. In more detail, simulations can not only provide evidence for the characterization of the liquid crystalline phases of different OPEs, but elucidate the role of charge transfer states in donor-acceptor LCs containing an endohedral metallofullerene moiety. Such systems can be regarded as promising candidates for organic photovoltaics. Furthermore, exciton dynamics simulations are performed as a way to obtain additional information about the degree of order in OPE columnar phases. Finally, ab initio and molecular mechanics simulations are used to investigate the influence of an applied electric field on pentacene reactivity and stability. The reaction path of pentacene thermal dimerization in the presence of an external electric field is investigated; the results can be related to the fatigue effect observed in OFETs, that show significant performance degradation even in the absence of external agents. In addition to this, the effect of the gate voltage on a pentacene monolayer are simulated, and the results are then compared to X-ray diffraction measurements performed for the first time on operating OFETs.
49

Computational insight into materials properties

Dallavalle, Marco <1986> 08 April 2015 (has links)
The aim of the work was to explore the practical applicability of molecular dynamics at different length and time scales. From nanoparticles system over colloids and polymers to biological systems like membranes and finally living cells, a broad range of materials was considered from a theoretical standpoint. In this dissertation five chemistry-related problem are addressed by means of theoretical and computational methods. The main results can be outlined as follows. (1) A systematic study of the effect of the concentration, chain length, and charge of surfactants on fullerene aggregation is presented. The long-discussed problem of the location of C60 in micelles was addressed and fullerenes were found in the hydrophobic region of the micelles. (2) The interactions between graphene sheet of increasing size and phospholipid membrane are quantitatively investigated. (3) A model was proposed to study structure, stability, and dynamics of MoS2, a material well-known for its tribological properties. The telescopic movement of nested nanotubes and the sliding of MoS2 layers is simulated. (4) A mathematical model to gain understaning of the coupled diffusion-swelling process in poly(lactic-co-glycolic acid), PLGA, was proposed. (5) A soft matter cell model is developed to explore the interaction of living cell with artificial surfaces. The effect of the surface properties on the adhesion dynamics of cells are discussed.
50

Search for a Diffuse Neutrino Emission in the Southern Sky with the Antares Telescope

Fusco, Luigi Antonio <1988> 23 March 2016 (has links)
Compelling evidence of the existence of cosmic neutrinos has been reported by the IceCube collaboration. Some features of this signal could be explained by a Northern/Southern sky asymmetry of the flux. This possible asymmetry would be related to the presence of the bulk our Galaxy in the Southern sky. The ANTARES neutrino telescope, located in the Mediterranean Sea, consists of a three dimensional array of 885 10-inch photomultiplier tubes distributed along twelve vertical lines. Its effective area and its good exposure to the Southern Sky would allow to constrain an enhanced muon neutrino emission from extended sources. An excess of events from the Galactic Plane is searched for. A signal region around the inner Galactic Plane is defined; the background from atmospheric events is estimated looking at data from off-zones for which ANTARES has the same exposure as for the signal region. The ANTARES sensitivity to such a flux has been computed. The results of the analysis after unblinding will be presented.

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