Physical and chemical aspects of the interaction of molecules with external surface and structural cavities of nanomaterials.

The research work carried out during this PhD project has been aimed to the investigation of molecular surface events relevant for the catalytic formation, in mild conditions, of amide/peptide bonds from non-activated reagents adsorbed on nanomaterials. The formation of C-N bonds is among the topics of high interest in modern research in chemistry, addressing issues ranging from fine to prebiotic chemistry. The implementation of this project required the selection of both catalyst and reactants. As for the nanomaterials, the criteria of choice were simplicity, availability and low cost for possible future applications and, on the other hand, reasonable representativeness of minerals possibly present on the early Earth, and active as catalyst towards adsorbed organic molecules. On this basis the following nanoparticles of silica and titania are selected as well as a zeolite of the ZSM-10 type, with a MOZ framework. This latter material was intended as a porous host for future studies of the high pressure induced oligomerization of amino acids. This part of the work belongs to a very recent project, and then the work carried out in this respect in this PhD thesis is focused on the synthesis of zeolite particles with proper framework features. The choice of reactants was driven, on one hand, on the suitability to be studied in depth by both experimental methods and theoretical modelling, and on the other hand, by the possibility to adsorb them on surfaces of nanomaterials from the vapour phase, i.e. in highly controlled conditions. Thus, the simplest carboxylic acid, HCOOH was selected, as well as two simple primary amines (methylamine and 1-pentanamine). One of the surface reaction investigated was the oligomerization of amino acids on the nanomaterials and for this glycine, alanine, histidine, serine were selected because of the possibility to adsorb them on catalyst via a chemical vapour deposition method. In summary, in Chapter One, the study targeting the elucidation of the mechanism of the amide bond formation between non-activated carboxylic acids and amines at the surface of amorphous silica is reported. The results prepare the ground to address the occurrence of this reaction and of the oligomerization of amino acids (glycine and alanine) at the surface of \u3b1-quartz sub-micrometric particles (Chapter Two). The study of the C-N bond formation at the surface of titania nanoparticles is the object of Chapters Three to Five. In particular, Chapter Three is devoted to the investigation the structural requirements of sites expose at the surface of titania nanoparticles in order they can act as catalytic sites towards amino acid oligomerization. In Chapter Four, insights on basic aspects of the interaction of formic acid and methylamine with the 101 anatase titania surface are presented. The possibility to prepare Ser-His dipeptides starting from non-activated amino acids by using titania nanoparticle as catalyst and the possible hydrolytic activity of the obtained peptides is the object of Chapter Five. Finally, in Chapter Six, challenges, successes and problems still to be solved for and effective synthesis of large ZSM-10 particles, required for multitechniques investigations, including single crystal X-ray diffraction

Redetermination and invariom refinement of 1-cyclo­propyl-6-fluoro-4-oxo-7-(piperazin-4-ium-1-yl)-1,4-dihydro­quinoline-3-carboxyl­ate hexa­hydrate at 120 K

The structure of the title compound, C17H18FN3O3·6H2O, has been redetermined at 120 K. An invariom refinement, a structural refinement using aspherical scattering factors from theoretically predicted multipole population parameters, yields accurate geometry and anisotropic displacement parameters, including hydrogen-bonding parameters. All potential hydrogen-bond donors and acceptors are involved in hydrogen bonding, forming an intricate three-dimensional network of N—H⋯O and O—H⋯O bonds

vanilla-option-pricing: Pricing and market calibration for options on energy commodities

Abstract The Python package vanilla-option-pricing implements procedures to price European vanilla options under the Black framework, using different stochastic models for the underlying asset. Currently, the geometric Brownian motion, the Ornstein–Uhlenbeck process and a two-factor mean-reverting process are available. The library supports market calibration, providing tools to tune the parameters of the stochastic processes against a set of listed options. The intended audience for the package is made of researchers and practitioners interested in quantitative finance and energy derivatives

Actualización de informe previo. Eficacia y seguridad de repelentes de mosquitos para uso humano disponibles en Uruguay

Existe una creciente preocupación en las Américas por la expansión de enfermedades transmitidas por vectores, especialmente las transmitidas por mordeduras de mosquito. Los vectores son organismos vivos que transmiten enfermedades infecciosas al ser humano. El principal problema de estas infecciones radica en su fácil diseminación, en la ausencia de tratamientos específicos para muchas de estas enfermedades y en la falta de desarrollo de vacunas para la prevención de algunas de ellas. Entre las enfermedades más conocidas transmitidas por mosquitos se destaca por su actual aumento las trasmitidas por el mosquito Aedes aegypti: dengue, chikungunya y virus zika

Study on the performances of a PET system used for the control of the dose in hadrontherapy

The Positron Emission Tomography is a technique of medical imaging widely used to diagnose tumoural masses making use of the capability of a radiotracer (18F − F DG) to reach, thanks to biological metabolism, sick organs; 18 F is a β+ emitter with half-life of about 109 minutes, after the decay the positron annihilates with an electron of the body emitting two gamma rays back-to-back of energy of 511 keV. Then, it is possible to go back to the position of the annihilation process by revealing the two photons with detectors placed all around the patient. The use of particles beams (like: photons, electrons and hadrons) for medical purpose has been developed thanks to progress in the construction of particle accelerators. In particular hadrontherapy exploits heavy particle beams to destroy tumoural masses inside the body. Particles commonly used are protons and carbon ions, they deliver almost all their energy in a narrow peak, whose depth depends upon the energy of the ions, so it is possible to reach deep organs by tuning the energy of the beam. Another advantage to make use of hadrons comes from the fact that the energy released to healthy tissues is less than that released by photons or electrons, considering the same dose deposited on tumor. In the last decades it began to think to the possibility of applying the principle of photon detection of a PET scanner to monitor the dose released in tissues by beams employed in hadrontherapy. This is feasible because when an hadron beam crosses matter it produces isotopes, like 11 C or 15 O, that are β+ emitters; then, after radioactive decay and the annihilation with an electron, they will produce two γ rays, which, once revealed, give the distribution of isotopes and so it is possible to localize where the beam has interacted. In this work of thesis it has been characterized a PET scanner, named DoPET, planned for the monitoring of the dose in hadrontherapy. It consists of two planar heads of detector, each of them is composed by four independent scintillator LYSO matrices, coupled with positions sensitive photomultiplier tubes and connected with an electronic system of data acquisition. The analysis pertains to the performance of the device, and it covers various aspects of the system. The measures were made referring to the NEMA standard protocol, but, since it refers to the PET scanners with a circular geometry used for research on small animals, some of these analysis had to be adapted to planar geometry. The first study is linked with the calibration of the system, which is necessary before the reconstruction of images. The first step of this calibration is the pixel identification, it is required because on the edges of the crystal pixels are not always well resolved, then it is necessary the energy calibration to convert spectra from raw ADC channels to energy channels. It was noticed that positions of pixels changed, respect to those identified with calibration, with varying of the rate of the source. So it is tested a method to correlate the correction of pixel maps with the rate of the source and then it is included in the reconstruction software to avoid the wrong attribution of events in pixels changing the activity. The analysis about the dead-time of the device concerns the estimation of the Constant Fraction Discriminator dead-time and the verification that modularity of the detector improves dead-time performances of the device, as predicted by simulations. Furthermore the dead-time correction is introduced inside the reconstruction software to obtain the correct rate of the source. The study about the spatial resolution of the device was done with two different radioactive sources, and it was observed the same behavior by the system, so that the resolution at the center of the device was worse than in other points of the Field Of View, this fact is due to parallax error, which is more significant at the center rather than on borders, because of the geometry of the scanner. The study about the Noise Equivalent Count rate is important to know the maximum range of applicability in-beam, namely at which rate the signal to noise ratio is still favorable; in fact increasing the activity of the source noise grows more than signal, degrading the quality of data. The NEC curve is calculated as the ratio between the true coincidence rate square and the sum of all acquired coincidences; from the position of the peak of the curve it is possible to go back to the maximum advantageous value of activity