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

Anisotropic compression in the high pressure regime of pure and Cr-doped vanadium dioxide

We present structural studies of V$_{1-x}$Cr$_x$O$_2$ (pure, 0.7% and 2.5% Cr doped) compounds at room temperature in a diamond anvil cell for pressures up to 20 GPa using synchrotron x-ray powder diffraction. All the samples studied show a persistence of the monoclinic $M_1$ symmetry between 4 and 12 GPa. Above 12 GPa, the monoclinic $M_1$ symmetry changes to isostructural $M_x$ phase (space group $P2_1/c$) with a significant anisotropy in lattice compression of the $b$-$c$ plane of the $M_{1}$ phase. This behavior can be reconciled invoking the pressure induced charge-delocalization

Non-HDL cholesterol predicts coronary heart disease in primary prevention: findings from an Italian a 40-69 year-old cohort in general practice

Scopo. La frazione lipoproteica denominata “colesterolo non-HDL” viene raccomandata come un indice di rischio coronarico (RC) associata alla dislipidemia combinata ed è stata trovata un utile fattore predittivo del rischio coronarico nei pazienti diabetici. Abbiamo studiato l’associazione tra i fattori di RC noti, incluso la colesterolo non-HDL ed una “condizione di RC elevato”, cioè un “RC a 5-anni >15%” in medicina generale. Metodi. Abbiamo studiato 4085 individui di età 40-69 anni, 489 diabetici e 3596 non-diabetici, appartenenti ad una coorte opportunistica. Sono state utilizzate le statistiche descrittive, e la regressione logistica multivariata aggiustata per età e sesso per i confronti tra i 2 gruppi. Risultati. Circa il 12% dei participanti era diabetico. I confronti aggiustati per età e sesso hanno mostrato che tutte le variabili erano significativamente peggiori nei diabetici rispetto ai non-diabetici (eccetto fumo, colesterolo totale e rapporto colesterolo totale/HDL). I diabetici avevano un “RC medio a 5-anni” più alto dei non-diabetici (18.8±11.9% vs 7.5±6.9%, P15%” (55.4% vs 11.1%, P<0.01). Nei diabetici, le variabili associate ad una “condizione di RC elevato” sono: fumo, pressione arteriosa sistolica (PAS) e colesterolemia non-HDL; nei non-diabetici: fumo, PAS, colesterolemia non-HDL e HDL (inversamente). Conclusioni. Il colesterolo non-HDL – oltre a fumo e PAS – è un forte predittore di una “condizione di RC elevato” sia negli individui diabetici che non-diabetici

La piccola industria italiana e le sue scelte tecnologiche. Un caso esemplare: i proiettori delle Officine Pio Pion

Analisi e ricostruzione storica delle vicende dell'azienda Pio

Pressure-Induced Effects in Organic-Inorganic Hybrid Perovskites

In this Perspective, we provide an overview of the pressure-induced effects on hybrid organic-inorganic perovskite for photovoltaics applications. It is shown that a fine-tuning of the most relevant photovoltaic properties, including band gap and carrier lifetime, is indeed possible by applying pressure over a rather small range and that such phenomena closely correlate with pressure-induced structural changes. High-pressure research can be used to search for new materials since the high-pressure structural configuration can be used as a model for tailoring ambient pressure compounds under proper chemical substitution, and the band gap tuning and enhancement of carrier lifetime with applied pressures can be a guide to design new hybrid perovskites with desired optical properties as a function of structural parameters