Competition between Polar and Antiferrodistortive Modes and Correlated Dynamics of the Methylammonium Molecules in MAPbI3_3 from Anelastic and Dielectric Measurements

The mechanisms behind the exceptional photovoltaic properties of the metallorganic perovskites are still debated, and include a ferroelectric (FE) state from the ordering of the electric dipoles of the organic molecules. We present the first anelastic (complex Young's modulus) and new dielectric measurements on CH$_{3}$NH$_{3}$PbI$_3$, which provide new insight on the reorientation dynamics of the organic molecules, and the reason why they do not form a FE state. The permittivity is fitted within the tetragonal phase with an expression that includes the coupling between FE and octahedral tilt modes, indicating that the coupling is competitive and prevents FE ordering. The onset of the orthorhombic phase is accompanied by sharp stiffening, analogous to the drop of permittivity, due to the hindered molecular dynamics. On further cooling, an intense anelastic relaxation process without a dielectric counterpart suggests the reorientation of clusters of molecules with strong antiferroelectric correlations.Comment: accepted in J. Phys. Chem. Let

Cinema in the training of psychiatry residents: focus on helping relationships

Background: Medical schools are currently charged with a lack of education as far as empathic/relational skills and the meaning of being a health-care provider are concerned, thus leading to increased interest in medical humanities. Discussion. Medical humanities can offer an insight into human illness and in a broader outlook into human condition, understanding of one self, responsibility. An empathic relation to patients might be fostered by a matching approach to humanities and sciences, which should be considered as subjects of equal relevance, complementary to one another. Recently, movies have been used in medical - especially psychiatric - trainees education, but mainly within the limits of teaching a variety of disorders. A different approach dealing with the use of cinema in the training of psychiatry residents is proposed, based on Jung and Hillman's considerations about the relation between images and archetypes, archetypal experience and learning. Summary. Selected full-length movies or clips can offer a priceless opportunity to face with the meaning of being involved in a care-providing, helping profession

CuO nanoparticles and microaggregates: an experimental and computational study of structure and electronic properties

The link between morphology and properties is well-established in the nanoparticle literature. In this report, we show that different approaches in the synthesis of copper oxide can lead to nanoparticles (NPs) of different size and morphology. The structure and properties of the synthesized NPs are investigated with powder X-ray diffraction, scanning electron microscopy (SEM), and diffuse reflectance spectroscopy (DRS). Through detailed SEM analyses, we were able to correlate the synthetic pathways with the particles’ shape and aggregation, pointing out that bare hydrothermal pathways yield mainly spheroidal dandelion-like aggregates, whereas, if surfactants are added, the growth of the nanostructures along a preferential direction is promoted. The effect of the morphology on the electronic properties was evaluated through DRS, which allowed us to obtain the electron bandgap in every system synthesized, and to find that the rearrangement of threaded particles into more compact structures leads to a reduction in the energy difference. The latter result was compared with Density Functional Theory (DFT) computational models of small centrosymmetric CuO clusters, cut from the tenorite crystal structure. The computed UV-Vis absorption spectra obtained from the clusters are in good agreement with experimental findings

Caratterizzazione Minero-Petrografica e Geochimica di Due Cave di “Marmo Onice” del Monte Circeo (Lazio, Italia): Alabastro Giaccione e Cotognino”

The calcareous alabaster was used to carry out historical and archaeological artifacts. Its diffusion was very increased in imperial age when quarries of Circeo mountain exploitation began. Coloured litotype exploitated more times in the past were studied, in fact archaeologies have found evidences in many roman remains of Giove Anxur temple near Terracina and in some covering slabs and columns in monumental churches of XVI-XVIII centuries. The 2 quarries are near San Felice Circeo town (“Guardi D’Orlando – Monticchio and “La Batteria”); “cotognino” alabaster and “a giaccione” alabaster was carried out from these 2 sites, these 2 litotypes was considered very valuable some years ago. Alabaster formation of “Monticchio” ore is made up from calcareous water circulation into the jointing of Circeo liassic limestones, it is constituted of crystalline stalactitic concretions, sometimes many zones show gradation of colour from honey to intense brown, and it is called “cotognino”. “Giaccion” alabaster take its name to be like ice, in fact it shows colours from white to bright yellow, and is into the liassic fractured limestones. By the light of this thin section analyses, X-ray diffractometry, RI determination, X-ray fluorescence and C, O and Sr isotopic analyses was carried out from each samples. A geologic characterization is defined, considering minero-petrographic, chemical and geochemical features, to solving archaeometric problems about artifacts made up to alabaster lithotypes

Study for restoration purposes about the obelisk located in "piazza della libertà" at ostuni (brindisi, Southern Italy)

Stone materials composing the St. Oronzo Rococ (local Baroque) obelisk, dedicated to patron saint of Ostuni in 1771 AD, were characterised. The monument is located in "Piazza della Libertà" at Ostuni (Brindisi, Southern Italy). The obelisk is composed of two different lithotypes, more or less pure Cretaceous limestone, with a variable porosity and biogenous component. Mineralogical, petrographical, geochemical and palaeontological and 87Sr/86Sr datation comparisons between finding lithotypes and Cretaceous limestones cropping out in four quarries already studied from some authors in the Ostuni sector, allow to ascribe obelisk samples to megabreccia quarry of Melpignano close to the ancient city wall of Ostuni. On the most used lithotype, recognised and sampled in the quarry, physical, mechanical and ageing tests have been carried out. These tests have evidenced the high porosity of the materials and have furnished some indications about utilisation and restoration methods