[en] Magnetic Resonance Imaging (MRI) has been proved to be a very sensitive method for detecting demyelinating lesions in multiple sclerosis. Therefore, MRI was used to study patients with optical neuritis, to evaluate the possible presence of demyelinating lesions in the brain. The prognostic value of cerebrospinal fluid findings was also evaluated. 15 refs.; 4 tabs

[en] Highlights: • Low-cost, MIP-based electrochemical sensor for 2-furaldehyde detection in beverages. • Electrochemical transduction by a screen-printed cell drop-coated with MIP. • MIP’s imprinted sites with different affinity for 2-furaldehyde. • MIP’s sites with relatively low affinity exploited for sensing 2-furaldehyde in white wine. • Experimental design method used for optimizing the instrumental parameters. There is an increasing interest in determining the concentration of furanic compounds naturally formed in food aqueous matrices, by in situ, fast and low-cost methods. A sensor presenting such characteristics is here proposed, and characterized. It is based on a molecularly imprinted polymer (MIP) as a receptor with electrochemical transduction on a screen printed cell (SPC). The molecularly imprinted polymer has been developed for a particular furanic derivative, 2-furaldehyde (2-FAL). The detection bases on the reduction of 2-FAL selectively adsorbed on the polymer layer in contact with the working electrode. The polymer layer is simply formed by in situ polymerization, directly over the SPC and it was characterized by IR, SEM and electrochemical methods. Even if based on an easy and fast preparation procedure, the layer sufficiently adheres to the cell surface giving a reusable sensor. Square wave voltammetry (SWV) was applied as the signal acquisition method. The sensor performance in aqueous solution (NaCl 0.1 M) was tested, obtaining that the dose-response curve is fitted by the Langmuir adsorption isotherm. The sensitivity, and so the limit of detection, were noticeably improved by a chemometric approach based on the Design of experiment method. (optimized conditions: E_step = 0.03 V, E_pulse = 0.066 V, f = 31 s⁻¹). In water solution at pH around neutrality the dynamic range was from about 50 μM to 20 mM. Similar results were obtained for a white wine containing 12% ethanol, which has been considered as a typical example of beverage possibly containing furhaldehydes. The higher limit of quantification can be modulated by the amount of MIP deposited, while the lower detection limit by the conditions of the electrochemical measurement.

[en] Research highlights: → Calcium hydride + magnesium-aluminum borides as candidates for hydrogen storage. → Long time ball milling improves hydrogen sorption kinetics of the CaH₂+MgB₂ system. → Coexistence of MgB₂ and AlB₂ does not improve hydrogen sorption performances. → Total substitution of MgB₂ with AlB₂ improves the system kinetics and reversibility. → Below 400 deg. C almost the full hydrogen capacity of the CaH₂ + AlB₂ system is reached. - Abstract: Among the borohydrides proposed for solid state hydrogen storage, Ca(BH₄)₂ is particularly interesting because of its favourable thermodynamics and relatively cheap price. Composite systems, where other species are present in addition to the borohydride, show some advantages in hydrogen sorption properties with respect to the borohydrides alone, despite a reduction of the theoretical storage capacity. We have investigated the milling time influence on the sorption properties of the CaH₂ + MgB₂ system from which Ca(BH₄)₂ and MgH₂ can be synthesized by hydrogen absorption process. Manometric and calorimetric measurements showed better kinetics for long time milled samples. We found that the total substitution of MgB₂ with AlB₂ in the starting material can improve the sorption properties significantly, while the co-existence of both magnesium and aluminum borides in the starting mixture did not cause any improvement. Rietveld refinements of the X-ray powder diffraction spectra were used to confirm the hypothesized reactions.

[en] In order to enhance capabilities for the reliable detection of nuclear material, improved detector materials are required. There is considerable room for improvement within the scintillator family of materials. However, native defects are present in all materials and impurities are similarly common. In scintillators, these defects serve as trap sites for electrons or holes, and therefore may contribute to decreased and delayed light yield. In fact, Lempicki and Bartram [J. Lumin. 81 (1999) 13] have proposed that understanding defect related phenomena is vital to the improvement of scintillators. It follows that if the most egregious electron/hole trapping defects are removed from the system, light output should increase. However, defect removal is difficult to achieve since often the defect-type to be removed is not known. In this paper, we assist the optimization of scintillators by employing atomic scale simulation techniques to predict the intrinsic defect structure of RE₃Al₅O₁₂ garnets (where RE ranges from Lu to Gd and Y). Specifically, we predict cation antisite defects to be the lowest energy intrinsic defect. Furthermore, we describe how our results can be used to interpret experimental observations

[en] Highlights: ► Highly ordered mesoporous SBA-15 and CMK3 matrices were prepared. ► Confinement of NaBH₄ into SBA-15 and CMK3 was performed by NH₃-free wet infiltration. ► Success in the confinement of NaBH₄ was proved by XRD and TEM. ► Confined NaBH₄ shows lower H₂ desorption temperature with respect to literature data. -- Abstract: In this work we focused on nanoconfinement of NaBH₄ into highly-ordered Si-based mesoporous scaffold and its carbon replica by ammonia-free wet chemical impregnation. Structural and morphological characterization, performed by X-ray diffraction and transmission electron microscopy enabled us to confirm the effectiveness infiltration procedure. Desorption properties tested by temperature programmed desorption analyses highlighted a noticeable shift towards lower temperature compared to both bulk material and samples of similar systems referred to in the bibliographical data

[en] Highlights: • A hybrid electrolyte membrane for LiB based on nanostructured YSZ was sintered HP-FAST. • The nano-porosity was retained and the membrane activated with a standard LiPF₆-EC-DMC solution. • The liquid is nano-confined in the ceramic membrane. • Excellent resistance to dendrite formation for more than 350 cycles in a Li/electrolyte/Li symmetrical cell. • The nano-porous ceramic hybrid electrolytes may be conveniently used in LMB. -- Abstract: The use of lithium metal as the anode for Lithium Metal Batteries (LMB) requires having solid or quasi-solid electrolytes able to block dendrites formation during cell cycling. Here we reported on a hybrid electrolyte membrane based on nanostructured yttria-stabilized-zirconia, sintered by means of High Pressure-Field Assisted Sintering Technique (HP-FAST) in order to retain proper nano-porosity, and activated with a standard LiPF₆-EC-DMC solution. By a thorough physico-chemical and functional characterization, we demonstrated that the liquid is effectively nano-confined in the ceramic membrane, and the resulting quasi-solid electrolyte is non-flammable. A remarkable conductivity value of 0.91 mS cm⁻¹ was observed at room temperature, with activation energy of 0.2 eV, and cation transference number, t⁺ = 0.55, substantially higher than that of the pure liquid electrolyte. The hybrid electrolyte showed electrochemical stability up to 5.5 V vs. Li⁺/Li, and excellent resistance to dendrite formation for more than 350 cycles in a Li/electrolyte/Li symmetrical cell. A full cell Li/electrolyte/LiMn₂O₄ showed more than 90 mAh g⁻¹ at 2C for more than 120 cycles. These very promising results indicated that nano-porous ceramic hybrid electrolytes may be conveniently used in LMB.

[en] The ignition and propagation mechanism of the self-propagating high-temperature synthesis of several cobalt and niobium aluminides was investigated. Two propagation mechanisms were identified depending on the stoichiometry of the starting mixture. Al-rich compositions propagate through a dissolution-precipitation mechanism while Al-poor mixtures require solid state diffusion. The ignition temperatures were measured by means of microthermocouples in quasi-adiabatic conditions through experiments carried out in thermal explosion mode. Ignition temperatures were found to be characteristic of each system and to depend strongly on reactants particle size. Ignition energies for all compositions were evaluated through a mathematical model

[en] Highlights: ► Nanoconfinement of 2NaBH₄ + MgH₂ into SBA-15 silica was successful in improving the thermodynamic and kinetic properties of the multi-component system ► The use of NbF₅ as additive reduced the NaBH₄ decomposition temperature and increased the desorption kinetics. ► Destabilization of hydrides can be gained by synergic effect of nanoconfinement and use of additive materials. - Abstract: We focus on the H₂ desorption properties of the 2NaBH₄ + MgH₂ system destabilized by different methods. Nanostructured powder mixtures were prepared by ball milling the starting hydrides and nanoconfined reactive composites were obtained by melting infiltration of the hydrides into a Si-based SBA-15 support. NbF₅ was tested as catalyst in both the preparations. Structural characterization by X Ray Diffraction and Transmission Electron Microscopy allowed evaluating the successful synthesis of SBA15 matrix, the microstructural features of ball milled and nanoconfined hydrides as well as the success of infiltration process. The evaluation of the sorption properties, by manometric Sievert-type apparatus and thermal desorption spectroscopy, revealed the efficiency of the hydride destabilization, obtained by the different routes, in decreasing the hydrogen release temperature and improving desorption kinetics.

[en] Highlights: • The desorption mechanism of LiBH_4 + LiAlH_4 was studied by in situ SR-PXD • The formation of unidentified intermediate was proved by experimental evidences. • This intermediate is based on Li, B, Al, H atoms. - Abstract: In the present work we focus the attention on the phase structural transformations occurring upon the desorption process of the LiBH_4 + LiAlH_4 system. This study is conducted by means of manometric–calorimetric, in situ Synchrotron Radiation Powder X-ray Diffraction (SR-PXD) and exsitu Solid State Magic Angle Spinning (MAS) Nuclear Magnetic Resonance (NMR) measurements. The desorption reaction is characterized by two main dehydrogenation steps starting at 320 and 380 °C, respectively. The first step corresponds to the decomposition of LiAlH_4 into Al and H_2via the formation of Li_3AlH_6 whereas the second one refers to the dehydrogenation of LiBH_4 (molten state). In the range 328–380 °C, the molten LiBH_4 reacts with metallic Al releasing hydrogen and forming an unidentified phase which appears to be an important intermediate for the desorption mechanism of LiBH_4–Al-based systems. Interestingly, NMR studies indicate that the unknown intermediate is stable up to 400 °C and it is mainly composed of Li, B, Al and H. In addition, the NMR measurements of the annealed powders (400 °C) confirm that the desorption reaction of the LiBH_4 + Al system proceeds via an amorphous boron compound