Interaction of a Long Alkyl Chain Protic Ionic Liquid and Water

A combined experimental/theoretical approach has been used to investigate the role of water in modifying the microscopic interactions characterizing the optical response of butyl-ammonium nitrate (BAN) water solutions. Raman spectra, dominated by the signal from the protic ionic liquid, were collected as a function of the water content, and the corresponding spatial organization of the ionic couples, as well as their local arrangement with water molecules, was studied exploiting classical molecular dynamics calculations. High quality spectroscopic data, combined with a careful analysis, revealed that water affects the vibrational spectrum BAN in solution: as the water concentration is increased, peaks assigned to stretching modes show a frequency hardening together with a shape narrowing, whereas the opposite behavior is observed for peaks assigned to bending modes. Calculation results clearly show a nanometric spatial organization of the ionic couples that is not destroyed on increasing the water content at least within an intermediate range. Our combined results show indeed that small water concentrations even increase the local order. Water molecules are located among ionic couples and are closer to the anion than the cation, as confirmed by the computation of the number of H-bonds which is greater for water-anion than for water-cation. The whole results set thus clarifies the microscopic scenario of the BAN-water interaction and underlines the main role of the extended hydrogen bond network among water molecules and nitrate anions.Comment: 27 pages, 10 figure

High-pressure behavior of methylammonium lead iodide (MAPbI3) hybrid perovskite

In this paper we provide an accurate high-pressure structural and optical study of MAPbI3 hybrid perovskite. Structural data show the presence of a phase transition towards an orthorhombic structure around 0.3 GPa followed by full amorphization of the system above 3 GPa. After releasing pressure the systems keeps the high-pressure orthorhombic phase. The occurrence of these structural transitions is further confirmed by pressure induced variations of the photoluminescence signal at high pressure. These variations clearly indicate that the bandgap value and the electronic structure of MAPI change across the phase transition.Comment: 23 pages, 9 figure

A case report of femoral head fracture with osteochondral lesion treated by osteosynthesis and biomimetic scaffold: 2-year clinical and radiological follow-up

The aim of the present study was to present clinical and radiological outcome of a hip fracture-dislocation of the femoral head treated with biomimetic osteochondral scaffold. An 18-year-old male was admitted to the hospital after a motorcycle-accident. He presented with an obturator hip dislocation with a type IVA femoral head fracture according to Brumback classification system. The patient underwent surgery 5 days after accident. The largest osteochondral fragment was reduced and stabilized with 2 screws, and the small fragments were removed. The residual osteochondral area was replaced by a biomimetic nanostructured osteochondral scaffold. At 1-year follow-up the patient did not complain of hip pain and could walk without limp. At 2-year follow-up he was able to run with no pain and he returned to practice sports. Repeated radiographs and magnetic resonance imaging studies of the hip showed no signs of osteoarthritis or evidence of avascular necrosis. A hyaline-like signal on the surface of the scaffold was observed with restoration of the articular surface and progressive decrease of the subchondral edema. The results of the present study showed that the biomimetic nanostructured osteochondral scaffold could be a promising and safe option for the treatment of traumatic osteochondral lesions of the femoral head. Study Design: Case report