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Drugs delivery into the brain across the blood brain barrier has always remained a challenging task for neuroscientists. Nanotechnology is now providing new prospective in the treatment of neurological cancer, neurovascular disorders and neurodegenerative diseases. This study aims to explore whether gold nanoparticles (AuNPs) are able to cross the blood brain barrier (BBB) and more importantly whether they have cytotoxic effects after in vivo and in vitro uptake. We selected AuNPs for their stability, size controlled synthesis, relatively easy surface modification with amine and thiol groups and capability to be studied at ultrastructural level with electron microscopy. Alkanethiol pyrazol was used to stabilize AuNPs. Thiol ligands strongly bind gold molecules due to soft character of both Au and S. Nanoparticles with a mean particle size < 2 nm were obtained. These nanoparticles had an absorption spectrum at 350 nm and showed a broad emission ranging from 400 to 600 nm depending on their quantum size since their emission shift from green to red when they form clusters of ~200 nm of diameter. In order to explore in vivo uptake of gold nanoparticles, 0.2 ml of saline suspension containing AuNPs (1x105) or physiological solution (as control) were injected into the carotid artery respectively of n=3 anesthetized mice. After 90 min from administration, the animals were sacrificed and the hindbrain slices were studied with an epifluorescence microscope. A strong particleassociated florescence was observed in the Caudato Putamen region (CPu) for AuNPs treated and not for untreated control. The fluorescence shows a more evenly spread distribution in the neuronal but not in glial cells, as shown by GFAP, Iba1 and NeuN immunoistochemistry. In order to explore in vitro cellular uptake the human neuroblastoma cells SH-SY5Y were incubated with 1 ml of saline suspension containing AuNPs (1x105) at 20 min, 1, 2 and 4 hrs. AuNPs internalization was observed through Leica microscope workstation B6000 equipped for in vivo time lapse analysis and, furthermore, confirmed by transmission electron microscopy observations. The effect of AuNPs was investigated both in vivo and in vitro using caspase-3 immunoreactivity and TUNEL test which showed apoptosis. In vivo many CPu neurons loaded with AuNPs were both caspase- 3 and TUNEL labelled as in vitro neuroblastoma cells whereas glial cells were AuNPs unloaded and caspase-3 or TUNEL negatives. Our data suggest that AuNPs cross the BBB and have particular imaging properties since they cluster into the cells changing the emission spectrum from green to red. Noteworthy AuNPs are cytotoxic so they are an attractive platform for neurological diseases if specifically addressed toward target cells.

We have experimentally investigated the expansion mechanism induced by laser irradiation of H2SO4 intercalated graphite. Intercalated graphite materials irradiated by laser allows to study reactions occurring in confined chemical conditions. We find that the laser-assisted reaction process is characterized by a threshold temperature of about 140{\deg}C followed by a fast rate of heating which produces a large amount of overheated gases and causes a violent expansion of the graphite crystal. We investigate the morphological changes undergone by irradiated graphite filaments using a combination of thermal and visible imaging technique which allows for the quantitative determination of temporal evolution of the thermal field during the heating stage and exfoliation of the grain.

We experimentally study the polarization dynamics in a quasi isotropic CO2 laser emitting on the *01 TEM mode subjected to an optical feedback. We observe a complex dynamics in which spatial mode and polarization competition are involved. The observed dynamic is well reproduced by means of a model that provides a quantitative discrimination between the intrinsic asymmetry due to the kinetic coupling of molecules with different angular momenta and the anisotropy induced by the polarization feedback. Possible applications to polarization coding and synchronization will be presented.

The hydrodynamic fluid description, proposed many years ago by E. Madelung (1927) for quantum mechanics, is used to discuss the class of nonlinear Schr̈odinger equations. In the case of stationary profile solutions the equation satisfied by the fluid density ρ = {pipe}Ψ{pipe}2 is integrated and periodic solutions expressed through Jacobi elliptic functions are derived for cubic and cubic + quintic nonlinearities. In the limit case k2 = 1 the solitary wave solution found for the cubic + quintic nonlinearity proves to be much steeper and narrower than the one-soliton solution of the cubic NLS equation.

Fresnel tomograms of Laguerre-Gaussian beams are found and the relation of the two-point spatial correlation function with the tomographic map is discussed. The spatial distribution and signature of vorticity of Laguerre-Gaussian modes is analyzed by measuring the two-point spatial correlation function of the one-dimensional projection of the vortex field. An interferometric approach, based on a Fourier projection algorithm, for the experimental determination of the two-point correlation function of the full complex vortex field at the cross-section plane of the recorded interference pattern is also described; this approach allows one to characterize the vortex structure and spatial coherence along the direction of propagation

Delivery of pharmacologic agents to neurons in the brain across the blood brain barrier (BBB) remains a challenging task for neuroscientists. Because of their unique properties, nanoparticles have generated a great deal of interest for their potential use in therapeutics drug delivery. We investigated the use of colloidal gold (AuNP) in this context based on its characteristic stability as a metal nanoparticle. We explored the neuronal uptake of AuNPs both in vitro using SH-SY5Y human neuroblastoma cells and in vivo using direct brain injection in mice. AuNPs have a diameter of approximately 2 nm and an absorption spectrum with a peak at 350 nm. Due to their characteristic quantum size effect, the nanogold emission shifts from green to red upon forming clusters of approximately 200 nm in diameter. The clustered particles have a broad emission ranging from 400 to 600 nm. For the in vitro studies, we incubated SH-SY5Y cells with 1x105 AuNPs for 20 min, 1, 2 and 4 hrs. AuNP internalization was observed using a Leica microscope workstation B6000 equipped with an in vivo timelapse analysis capability. We confirmed our results using transmission electron microscopy (TEM). For in vivo, studies we injected a physiological solution containing 1x106 AuNPs into the carotid arteries of anesthetized mice (n=3). The physiological solution alone was injected into control mice for comparison. Our in vitro data demonstrated that gold-particles passed the cell membrane, clustered in the cytoplasm and induced apoptosis after 4 hrs of treatment. In vivo, a strong particle-associated florescence was observed in the cauda putamen region (CPu) 90 min after injection. Fluorescence was evenly distributed in the neuronal cells but was not observed in glial cells, as demonstrated by GFAP, Iba1 and NeuN immunoistochemistry. The cytotoxic effects of AuNPs were investigated both in vitro and in vivo using caspase-3 immunoreactivity and TUNEL assays for apoptosis. Our data suggest that AuNPs cross the BBB and have useful imaging properties that rely on clustering in cells, which changes their emission spectrum from green to red. Specific properties of these nanoparticles may offer new advantages as potential pharmaco-delivery tools in treatment of neurological diseases that may benefit from specific neuronal cell targeting.

An extensive characterization of the photorefractive bright soliton writing process in a lithium niobate crystal is presented. An interferometric approach based on a digital holographic technique has been used to reconstruct the complex wave field at the exit face of the crystal. Temporal evolution of both intensity and phase profile of the writing beam has been analysed. The effective changes of the refractive index of the medium during the writing process and after the soliton formation are determined from the optical phase distribution. This method provides a reliable way to observe the process of soliton formation, whereas the determination of the intensity distribution of the output beam does not show clearly whether the soliton regime has been achieved or not. Furthermore, a detailed analysis of the soliton in a steady-state situation and with different writing conditions is presented and discussed.

Using a Madelung fluid description a discussion is given for some generalized NLS equations. Solitary wave and periodic solutions are obtained for constant and stationary profile current velocity.