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Littérature scientifique sur le sujet « Spettroscopia forza »
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Articles de revues sur le sujet "Spettroscopia forza"
Mortilla, M., M. Ermini, M. Nistri, G. Dal Pozzo et F. Falcini. « Imaging e spettroscopia RM dell'idrogeno dell'encefalo in soggetti con LES ad esordio pediatrico ». Rivista di Neuroradiologia 10, no 2_suppl (octobre 1997) : 252. http://dx.doi.org/10.1177/19714009970100s2115.
Texte intégralSarchielli, P., R. Tarducci, O. Presciutti, F. Vicinanza, G. Guercini, G. P. Pelliccioli, G. Gobbi et V. Gallai. « Spettroscopia protonica in vivo nello studio della sclerosi laterale amiotrofica ». Rivista di Neuroradiologia 13, no 1 (février 2000) : 61–64. http://dx.doi.org/10.1177/197140090001300111.
Texte intégralThèses sur le sujet "Spettroscopia forza"
Cortelli, Giorgio. « Calibrazione microleva per AFM e spettroscopia di forza applicata a nanofibre polimeriche ». Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/14513/.
Texte intégralMurello, Anna. « La spettroscopia di forza basata sull'AFM nello studio dello spazio conformazionale e dei processi aggregativi di proteine prioniche ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/8878/.
Texte intégralCORTI, ROBERTA. « Single molecule force spectroscopy of proteins and DNA ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2020. http://hdl.handle.net/10281/273770.
Texte intégralIn the last few decades, the constant development of novel single molecule techniques has created the basis for a new paradigm in the field of biophysics. Among all, the nanomanipulation of individual biomolecules revealed new insights into the mechanics of biological molecules, in particular proteins and DNA, improving the understanding of the fundamental relation between structural properties and biological functions. Therefore, several single-molecule nanomanipulation methods have been developed, including Atomic Force Microscopy (AFM), Magnetic Tweezers (MT) and Flow Stretching (F-S) coupled with fluorescence. All these technique were employed in this Thesis for the characterisation of biological macromolecules by single molecule force spectroscopy (SMFS). In this Thesis I focus mainly on several aspects of a few different proteins trying to depict a frame in which the strong link between proteins function and their structure can be clarified. With this aim, I study the conformational states of an intrinsically disordered protein (IDP) involved in Parkinson's Disease, the a-synuclein (AS) and the structural change driving the DNA compaction mediated by structural maintenance protein, the condensin. Finally, I present a structural study of a DNA-analogue by thermal shifting essays and single molecule experiments. I included also a technical implementation of a (F-S) combined with TIRF set up to promote the high-speed exchanging buffer for study protein DNA interactions. In the AS single molecule force spectroscopy (SMFS) study, I afford the problem of AS lacking of well defined structure by stretching and unfolding a single polyprotein containing the human AS by employing a SMFS approach. The analysis of the different unfolding pathways gives information about the structural conformation of the protein before the mechanical denaturation. The AS was found to assume three distinct conformational states ranging from a random coil to a highly structured conformation. Since ligands, such as Epigallocatechin-3-Gallate (EGCG) and Dopamine (DA), are known to affect the fibrillation process of AS, I used this single molecule technique to investigate the effect of EGCG and DA on the conformational ensemble of the WT AS. Moreover, knowing from several studies that the presence of point mutations, linked to familial PD, correlate with the gaining of structure and therefore with AS aggregation, I SMFS studies also on AS with three different single point mutations (A30P, A53T and E83A). A particular emphasis was given to the comparison between SMFS results and native mass spectrometry data for the conformational changes of AS in the presence of both DA and EGCG. In the following part, related to the DAP: diaminopurine-substituted DNA, a systematic comparison between a wild-type DNA and DAP DNA is performed, in terms of thermal stability and nanomechanical properties, measured at low and high forces. At low forces the DNA extension and bending rigidity were investigated, by using both MT and AFM, while at high forces the overstretching transition behaviour was explored. In the section related to condensin mediated DNA collapsing, I present a single-molecule MT study to measure, in real-time, the compaction of individual DNA molecules by the condensin complex in the presence of ATP. Since many compaction traces showed sudden distinct decreases in the DNA end-to-end length, I present and validate two different very conservative user-bias-independent step-finding algorithm to extract the size of these compaction steps. Finally, a DNA flow stretching implementation is presented. Briefly, several flow cells were tested to achieve a fast buffer exchange in both MT and F-S coupled with TIRF, in the frame of visualisation of DNA:proteins interactions. We validated our flow cells in term of boundary exchange and applied force. We also visualized fluorescent DNA molecules stretched in the presence of several flow rates.
De, Carlo Martino. « Integrated optomechanical devices for sensing ». Doctoral thesis, 2021. http://hdl.handle.net/11589/213841.
Texte intégralOptomechanics is a developing field of research exploring the interaction between light and mechanical motion. The modern nanofabrication techniques for mechanical devices and ultralow dissipation optical structures have provided a way for giving an important experimental progress to optomechanics, both for applications and for fundamental investigations. In this thesis optomechanics will be investigated in different aspects, in its general meaning, both theoretically and experimentally. There are different ways in which light and mechanics interact with each other. In this thesis three different macro areas of optomechanics have been developed: optical gyroscopes, optomechanical forces and photoacoustic spectroscopy. The interaction between light and mechanical motion has been investigated starting from the concept of optical gyroscopes. Optical gyroscopes are sensors of angular velocity. In the present state of the art, the physical principles and the configurations used for realizing optical gyroscopes are not suitable for miniaturizing them to the microscale. In this thesis some new configurations exploiting the concept of "exceptional points" have been presented and investigated. According to the relativistic effect called Sagnac effect, the resonance frequencies of two counterpropagating modes in a ring resonator are separated by a quantity proportional to the angular velocity of the frame. However, the possibility of miniaturizing the optical gyroscope is limited by the fact that the resonance splitting is proportional to the radius of the ring resonator. In the first chapter the concept of parity-time symmetry has been introduced as a solution for the integration of angular velocity sensors. By setting up two coupled optical resonators designed to be at the so called "exceptional point", it could be demonstrated that the eigenfrequency splitting is proportional to the angular velocity of the device, with a sensitivity that is several orders of magnitude higher than the classical Sagnac gyroscope. In this thesis it has been demonstrated that one problem of the parity-time symmetric gyroscope is the instability of the optical eigenmodes when the system is in rotation. That is why the idea of the anti-parity-time-symmetric gyroscope was proposed, using a U-shaped auxiliary waveguide to indirectly couple two optical resonators. The proposed solution has been shown to be an interesting alternative for angular velocity sensing, thanks to the easy readout scheme and the absence of modes instability. A simple broadband source, together with a photodetector could be used to read the output of the sensor. Finally, a new configuration for an anti-parity-time-symmetric gyroscope has been proposed. It is different from the U-shaped configuration and uses only an auxiliary straight waveguide to indirectly couple two optical resonators. This architecture has been shown to be much more robust, insensitive to some fabrication errors, with respect to the U-shaped one. The second area of optomechanics that has been investigated in this thesis includes optomechanical forces. In particular, a generalized model able to calculate the mechanical displacement of only one degree of freedom of a general optomechanical setup has been developed. The model initially proposed by Rakich has been extended to systems where gain or loss are considered. Then, the model has been used to evaluate the effect of optical forces in parity-time symmetric system with suspended waveguides in the coupling region. It has been demonstrated that it is possible to enhance the optical forces thanks to condition of parity-time symmetry. Secondly, an analytical modelling of the dynamics of optomechanically coupled suspended optical waveguides has been proposed, including a modelling of the damping, with the squeezing effect. Such an analytical model, together with the numerical proposed algorithm can be used to find the evolution of the system in the time domain of complex optomechanical structures, such as optomechanical switches. Also, an experimental work on an optomechanical switch has been shown. All the fabrication steps to fabricate the integrated optomechanical device has been explained. The most critical part during the fabrication has been the underetching of suspended waveguides. In fact, using a wet HF etching process caused the suspended waveguides to get stuck. Using a ZEP mask and a vapor HF etching, unexpected HF bubbles appeared on the surface. So, a hard mask has been used to guarantee the successful underetching of the device. Finally, the experimental measurement on the chip showed the expected behaviour of the device. Finally, Photoacoustic Spectroscopy has been analysed. The state-of-art Quartz-Enhanced PhotoAcoustic Spectroscopy (QEPAS) sensor has been modelled and simulated and a new semi-integrated sensor has been proposed. One problem of the state-of-art QEPAS sensors is the necessity of alignment for optical components. Moreover, the dimension of all the devices involved in the setup makes it difficult to realize portable and compact sensors. The idea proposed in this thesis is to integrate all the optical components needed to guide the light in the proximity of the Quartz Tuning Fork to drastically reduce the dimension of the overall setup and to avoid the problem of optical alignment. The possibility of using integrated optical waveguides to guide light makes it possible to use optical resonators to enhance the photoacoustic signal that is read through a Quartz Tuning Fork. The proposed setup is meant to use an integrated laser bonded to a Silicon chip, where all the waveguides are realized. In this case a very small mechanical resonator can be bonded over the Silicon chip, in order to enhance the amplitude of the pressure signal. In such a way, performance comparable with the state-of-art QEPAS sensor can been achieved. Such a result could pave the way to a new generation of compact QEPAS sensor, that could overcome the problem of the size of the setups and of the alignment of optical components.
Triggiani, Maurizio. « Integration of machine learning techniques in chemometrics practices ». Doctoral thesis, 2022. http://hdl.handle.net/11589/237998.
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