We investigate the interfacial dynamics of a 2D self-organized mixed layer made of silica nanoparticles interacting with phospholipid (DPPC) monolayers at the air/water interface. This system has ...biological relevance, allowing investigation of toxicological effects of nanoparticles on model membranes and lung surfactants. It might also provide bio-inspired technological solutions, exploiting the self-organization of DPPC to produce a non-trivial 2D structuration of nanoparticles. The characterization of interfacial dynamics yields information on the effects of NPs on the mechanical properties, important to improve performances of systems such as colloidosomes, foams, creams. For this, we combine micro-tracking in real-space with measurement in momentum-space via x-ray photon-correlation spectroscopy and Digital Fourier Microscopy. Using these complementary techniques, we extend the spatial range of investigation beyond the limits of each one. We find a dynamical transition from Brownian diffusion to an arrested state driven by compression, characterized by intermittent rearrangements, compatible with a repulsive glass phase. The rearrangement and relaxation of the monolayer structure results dramatically hindered by the presence of NPs, which is relevant to explain some the mechanical features observed for the dynamic surface pressure response of these systems and which can be relevant for the respiratory physiology and for future drug-delivery composite systems.
The referendums on the modification of art. 41 of the Irish Constitution ABSTRACT: The aim of this essay is to describe and briefly analyse the events that lead to the referendum aiming to modify ...art. 41 of the Irish Constitution, and the position adopted by some important denominations towards the vote. SOMMARIO: 1. Introduzione - 2. Gli antecedenti - 3. La Citizens’ Assembly on Gender Equality - 4. Verso il referendum - 5. Il testo dei referendum - 6. Le confessioni religiose e i referendum - 7. Il voto - 8. Alcune brevi considerazioni.
A procedure for the optimization of a 3C–SiC buffer layer for the deposition of 3C–SiC/(001) Si is described. After a standard carbonization at 1125°C, SiH4 and C3H8 were added to the gas phase while ...the temperature was raised from 1125°C to the growth temperature of 1380°C with a controlled temperature ramp to grow a thin SiC layer. The quality and the crystallinity of the buffer layer and the presence of voids at the SiC/Si interface are related to the gas flow and to the heating ramp rate. In order to improve the buffer quality the SiH4 and C3H8 flows were changed during the heating ramp. On the optimized buffer no voids were detected and a high-quality 1.5μm 3C–SiC was grown to demonstrate the effectiveness of the described buffer.
•A procedure for the optimization of a 3C–SiC buffer layer for the deposition of 3C–SiC/(001) Si is presented.•Buffer layer quality and voids at interface depends on the gas flow and heating ramp rate. Lower ramp heating rate yield the best results.•On the optimized buffer very few density of voids were detected.•High-quality 1.5μm 3C–SiC was grown to demonstrate the effectiveness of the described buffer.
We validated here the applicability to hyperthermia treatment of magnetic nanocapsules prepared by the sequential layer-by-layer adsorption of polyelectrolytes and magnetic, Fe3O4 nanoparticles. For ...the shell preparation around a nanodroplet liquid core, biocompatible polyelectrolytes were used: poly l-lysine as the polycation and poly glutamic acid as the polyanion. The hyperthermia effect was demonstrated by applying the radio frequency (rf) magnetic field with maximum fields H up to 0.025 T and frequencies up to 430 kHz; we found sizable heating effects, with a heating rate up to 0.46 °C/min. We also found effects of irradiation on capsules’ morphology that indicated their disruption, thus suggesting their potential use as nanocarriers of drugs that can be locally released on demand. Therefore, these magnetically responsive nanocapsules could be a promising platform for multifunctional biomedical applications such as the controlled release of pharmaceuticals in combination with hyperthermia treatment.
We report on the synthesis and characterization of a composite nanostructure based on the coupling of cerium fluoride (CeF
3
) and zinc oxide (ZnO) for applications in self-lighted photodynamic ...therapy. Self-lighted photodynamic therapy is a novel approach for the treatment of deep cancers by low doses of X-rays. CeF
3
is an efficient scintillator: when illuminated by X-rays it emits UV light by fluorescence at 325 nm. In this work, we simulate this effect by exciting directly CeF
3
fluorescence by UV radiation. ZnO is photo-activated in cascade, to produce reactive oxygen species. This effect was recently demonstrated in a physical mixture of distinct nanoparticles of CeF
3
and ZnO Radiat. Meas. (2013) 59:139–143. Oxide surface provides a platform for rational functionalization, e.g., by targeting molecules for specific tumors. Our composite nanostructure is stable in aqueous media with excellent optical coupling between the two components; we characterize its uptake and its good cell viability, with very low intrinsic cytotoxicity in dark.
Silica nanoparticles (SiNP) can be incorporated in phospholipid layers to form hybrid organic–inorganic bidimensional mesostructures. Controlling the dynamics in these mesostructures paves the way to ...high-performance drug-delivery systems. Depending on the different hydrophobicity/hydrophilicity of SiNP, recent X-ray reflectivity experiments have demonstrated opposite structural effects. While these are reasonably well understood, less is known about the effects on the dynamics, which in turn determine molecular diffusivity and the possibility of drug release. In this work we characterize the dynamics of a mixed Langmuir layer made of phospholipid and hydrophobic SiNP. We combine X-ray photon correlation spectroscopy and epifluorescence discrete Fourier microscopy to cover more than 2 decades of Q-range (0.3–80 μm–1). We obtain evidence for the onset of an arrested state characterized by intermittent stress-relaxation rearrangement events, corresponding to a gel dominated by attractive interactions. We compare this with our previous results from phospholipid/hydrophilic SiNP films, which show an arrested glassy phase of repulsive disks.
To synthesize and characterize the performances of a new all-inorganic nanocomposite (NC) for self-lighted photodynamic therapy against cancer. This NC could allow radiotherapy doses to be reduced, ...as it enhances the effects of x-rays, generating cytotoxic reactive oxygen species as singlet oxygen.
The proposed NC combines CeF
and ZnO; CeF
absorbs 6-MeV x-rays and activates the photosensitizer ZnO. Characterization is performed by transmission electron microscopy (TEM), scanning-TEM, energy dispersive x-ray spectrometry and fluorescence spectroscopies. Efficiency on human adenocarcinoma cells (A549) was tested by fluorescence spectroscopy, cytofluorimetry, viability assays, clonogenic assays, cell cycle progression assays.
NC blocks A549's cell cycle before mitosis in the dark. Upon low-dose x-ray irradiation (2 Gy), reactive oxygen species/singlet oxygen are generated, further blocking cell cycle and reducing viability by 18% with respect to the sum of x-ray irradiation and NC dark activity.
These novel NCs promise to reduce doses in radiotherapy, helping to reduce unwanted side effects.
A high pressure die cast Mg-9%Al-1%Zn alloy was friction stir processed at two high rotation rates and advancing speeds. Tensile tests were performed at higher temperature to study the mechanical ...properties of the microstructure induced by the friction stir process. Fracture surfaces resulting from tensile tests were observed by scanning electron microscopy and investigated by microanalysis. The fracture occurred in the tmaz and inside the stirring zone, depending on deformation conditions (temperature and strain rate). The morphology of the fracture surface varied from ductile to brittle in the same sample depending on phase type. Microhardness was measured on cross sections perpendicular to the advancing direction of the stirring pin, at various depth levels, before performing tensile tests to estimate the attitude of a single region to be deformed.
Silicon carbide thin films were synthesised by vapour phase epitaxy technique on silicon substrates using silane and propane as precursors. Methyltrichlorosilane (MTS) was added, and nitrogen was ...used as dopant precursor. Samples with different doping concentrations were obtained varying the nitrogen flow during the growth. Doping level for each sample was assessed using Raman technique, and a correlation between dopant flow and doping level was confirmed. The influence of MTS on nitrogen incorporation is analysed and discussed: the introduction of MTS increases the growth rate and increases the doping level. We exclude a direct doping effect by the MTS, but we think that it promotes the incorporation of nitrogen doping species. The crystalline quality of the as-grown films was evaluated using X-ray diffraction, assessing the good crystalline quality even in samples obtained using high growth rates and high doping level.
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