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IL RUOLO DEI FARMACI ANTI-NEOANGIOGENICI NEL TRATTAMENTO DELLE METASTASI EPATICHE DA CARCINOMA COLO-RETTALE
No full textExperiments on strongly correlated materials under extreme conditions
No full textThe aim of this work has been to investigate the electronic phase transitions and the electronic dynamic behavior of 'strongly correlated materials'. In particular I will show data of three different classes of materials: iron-based superconductors, topological insulators and spin-crossover (SCO) materials, under conditions that can be considered extreme. Experiments have been performed under a variable DC magnetic field from 0 to 5 T, the temperature range was from 4.2 to 300 K and pressure applied was ranging from 0 to 3 GPa. Experiments were carried out the in the majority of the cases by measuring the DC and the AC magnetic susceptibility, while the last case regarded the infrared spectroscopy.
The results of the multi-harmonic magnetic susceptibility experiments on iron based superconductors show:
a) in the ‘1111’ NdFeAsO1-0.14F0.14, iron pnictide, the coexistence of a superconducting (Tc = 47 K) and a magnetic phase (Tm = 90 K);
b) the superconducting phase in the ‘1111’ iron pnictide exhibits good bulk 3D pinning characteristics with a crossover to a 2D behavior for a Hdc field of 1 T. In fact these systems have a layered crystal structure with alternate superconducting iron-pnictogen active layers and rare earth-oxide spacer layers;
c) a superconducting phase (Tc = 10 K) coexisting with a magnetic (Tm = 125 K) phase has been detected also in the ‘11’ FeSe1-xTex iron chalcogenide;
d) the superconducting phase in the ‘11’ iron-chalcogenides also exhibits good bulk 3D pinning characteristics at low magnetic fields;
e) the comparison between the ‘1111’ NdFeAsO1-0.14F0.14 iron pnictide superconductor and the ‘11’ iron chalcogenide superconductors properties, where only iron-chalcogen active planes are present, points out that the ‘1111’ iron superconductor has a stronger pinning force despite its higher thermal activation, related to the role of the (NdO) spacer layer.
Concerning topological insulators two samples Bi2Te3 and Bi0.6Sb1.4Te3 have been characterized with both DC and AC magnetic susceptibility at low temperature (> 4 K) and at high magnetic field (< 5 T), to eventually probe their ideal surface metallic states vs. the bulk response. DC magnetic measurements showed a bulk diamagnetic behavior in the Bi2Te3. Moreover, the AC susceptibility response of Bi2Te3 at 170 and 970 Hz has been measured with a small excitation field. Data do not apparently show the expected decrease of the bulk diamagnetic signal (real part) due to a slight imbalance of the spin-oriented surface currents resulting in a paramagnetic contribution. The phenomenon is probably due to the impossibility to generate the extremely high frequency of the excitation field necessary to probe only the surface states. However, susceptibility data show unusually high values of the leakage currents (imaginary part) and, increasing the frequency a significant increase of the amplitude. Results may be compatible with the occurrence of a contribution from surface spin-oriented states unbalanced by the exciting magnetic field. The Bi0.6Sb1.4Te3 shows a paramagnetic behavior vs. temperature under low magnetic fields and a unusual paramagnetic/diamagnetic transition at 5 K for DC fields Hdc > 1 T.
Furthermore during this work I contributed to the construction, assembly and commissioning of a new apparatus named Press-Mag-O that will allow investigation of materials under extreme conditions of low temperature (LT), high pressure (HP) and high magnetic field (HMF). This device is equipped by a highly sensitive SQUID magnetometer capable to probe the dynamic magnetic properties (AC susceptibility in the range 1 Hz - 5 kHz) concurrently with IR spectroscopy vs. pressure (< 20 GPa), DC magnetic field (up to 8 T) and temperature (4.2 - 300 K). In this respect, regarding the characterization of SCO materials, in the framework of a cooperation INFN/MEC, the High-Spin (HS) to Low-Spin (LS) transition induced by pressure has been monitored at room temperature in a iron coordination polymer. The sample has been characterized by IR spectroscopy and the occurrence of a transition between the two spin states has been clearly observed.
The thesis is structured as follows:
after a short introduction on the strongly correlated materials studied, in chapter 1 the AC and DC magnetic susceptibility technique and the instruments used are described. Moreover the glass pinning mechanism in type II superconductors and the critical state models used in the data analysis are discussed here. Also a brief introduction on the ‘SINBAD’ (Synchrotron Infrared Beamline At DANE) beamline is included in this section. Finally, the Cu-Be DAC cell to perform high-pressure experiments is presented.
In chapters 2 and 3, are presented the magnetic characterization of the ‘1111’ NdFeAsO1-0.14F0.14 iron pnictide and the ‘11’ FeSe0.88, FeSe0.5Te0.5, FeSe0.25Te0.75, FeTe0.8S0.2 iron chalcogenide superconductors. A comparison of the properties using data of multi-harmonic magnetic susceptibility experiments under high magnetic fields (< 5 T) at low temperature (> 4.2 K) is presented and discussed.
In chapter 4 is presented the magnetic behavior of the topological insulators Bi2Te3 and Bi0.6Sb1.4Te3 with AC and DC magnetic susceptibility at low temperature (> 4 K) and at high magnetic field (< 5 T).
In chapter 5 are summarized the characteristics and the performances of the Press-Mag-O apparatus under commissioning at the Frascati National Laboratories (LNF) of the National Institute of Nuclear Physics (INFN). Moreover, to illustrate the potential of this instrument, IR spectroscopy data of the SCO HS to LS transition in the [Fe(Butrz)3](BF4)2·2H2O polymer under high pressure (< 3 GPa) are showed
LE AMMINISTRAZIONI TRANSITORIE DELLE NAZIONI UNITE E LE VIOLAZIONI DEI DIRITTI UMANI
No full textLE AMMINISTRAZIONI TRANSITORIE DELLE NAZIONI UNITE - IN PARTICOLARE IN KOSOVO E TIMOR EST - E LA RESPONSABILITà DELLE STESSE PER LE VIOLAZIONI DEI DIRITTI UMANI COMMESSE DAGLI AGENTI INTERNAZIONALI NEI TERRITORI AMMINISTRAT
Search for SUSY events with off-pointing photons
No full textThe Standard Model of elementary particle is a well established theory but it still has some unsolved problems, ranging from the origin of particle mass to the nature of the Dark Matter. Recent theoretical and experimental advances have bought a new focus on proposals for new physics with massive and long-lived particles, which are common in several Supersymmetry models. This work is focused on the study of Gauge Mediated Supersymmetry Breaking (GMSB) model. According to the choice of the parameters, this model foresees the existence of a long-lived neutralino, decaying into a gravitino and a high energy, displaced photon. The GMSB model is very promising for early discoveries at the LHC because it combines relatively high production cross section with a very distinctive experimental signature
Le ricadute del rinnovamento della Geometria Descrittiva sulla formazione:il caso del chiaroscuro o rendering
No full textThe theory of shadows and chiaro-scuro is one of the “Applications of Descriptive Geometry”.
Re-reading “La Teoria delle Ombre e del Chiaro-scuro “ (Tessari 1880) the link-integration between the scientific basis of drawing and computer modelling was established in the context of the drive to the renewal of the knowledge on Descriptive Geometry acquired so far.
The study faces the scientific-disciplinary contents established for the subjects ICAR/17-Disegno (established by Legal Notice).
In order to avoid a blind imitative work, each problem has been revisited, by means of computer tools, making sure to:
verify results predicted by theory;
study the formal structures of bodies with the study of the behaviour of light on themselves (research of the shadow/shade contours or apparent contour, level of light intensity or chiaro-scuro), exploiting the potential of computer tools (accuracy, ease of generation of views);
consider the basic and/or important problems, however solvable independently with the various methods, with construction-visualisation (drawing in virtual space) of the linear shadows, applying all the “steps and elements” of representation (projections; intersections);
deepen the basic notions useful for the visual and practical experience (life drawing); the knowledge of theory (descriptive geometry); the use of classic representation (technical-artistic drawing); the exercise of computer modelling.The result of this verification (link-integration) falls within the general contribution to the teaching: thanks to the potential of the software, any desired view can be utilised for an illustration of the text up till now limited to those typical of classical representation methods.
In addition to this, both the accuracy of the software and the virtual manipulation of the model, made it possible, for some problems, to develop alternative solutions which are proposed as original contribution.
For every topic the contribution of a general nature is highlighted in blue and the original contribution is highlighted in red: the respective figures are framed with said colours.
For the figures the same numbering of the text of Tessari was kept and every exercise is illustrated from multiple views (captured from the computer model), ordered with the same whole number and with alphabetical suffixes (Fig. 24 a ; Fig. 24 b …). This text is translated from Italian.
Every problem is dealt within the space of one or two pages and more pages in some exception; any possible detailed development are added in the following page
