Metacarpal cortical bone loss and osteoporotic fractures in the Coimbra Identified Skeletal Collection

There has been considerable progress in recent years in our understanding of the patterns of cortical bone loss in the second metacarpal in archeological skeletal samples. Nevertheless, cortical data from reference skeletal collections are insufficient, and the possible connection of metacarpal cortical parameters with osteoporotic fractures has not been thoroughly addressed. As such, this article aims to identify and explain sex-specific and age-associated metacarpal cortical bone loss in a large sample (N = 302females: 154/males: 148) from the Coimbra Identified Skeletal Collection. Another objective is to evaluate the association of cortical and demographic features with osteoporotic fractures. Age-related endocortical bone loss is significant in women but not evident in men. Periosteal accretion of the bone is absent in both sexes. Overall, there is a net loss of the cortical bone in women, whereas cortical bone strength seems to be preserved in men. The prevalence of osteoporotic fractures is similar in both sexes, with age at death significantly influencing the probability of exhibiting a fracture. Metacarpal cortical index does not seem to be an independent risk factor for osteoporotic fractures in this sample.Fundacao para a Ciencia e a TecnologiaPortuguese Foundation for Science and Technology [SFRH/BPD/74015/2010

Perovskite-Polymer Blends Influencing Microstructures, Nonradiative Recombination Pathways, and Photovoltaic Performance of Perovskite Solar Cells

Solar cells based on organic inorganic halide perovskites are now leading the photovoltaic technologies because of their high power conversion efficiency. Recently, there have been debates on the microstructure-related defects in metal halide perovskites (grain size, grain boundaries, etc.) and a widespread view is that large grains are a prerequisite to suppress nonradiative recombination and improve photovoltaic performance, although opinions against it also exist. Herein, we employ blends of methylammonium lead iodide perovskites with an insulating polymer (polyvinylpyrrolidone) that offer the possibility to tune the grain size in order to obtain a fundamental understanding of the photoresponse at the microscopic level. We provide, for the first time, spatially resolved details of the microstructures in such blend systems via Raman mapping, light beam-induced current imaging, and conductive atomic force microscopy. Although the polymer blend systems systematically alter the morphology by creating small grains (more grain boundaries), they reduce nonradiative recombination within the film and enhance its spatial homogeneity of radiative recombination. We attribute this to a reduction in the density of bulk trap states, as evidenced by an order of magnitude higher photoluminescence intensity and a significantly higher open-circuit voltage when the polymer is incorporated into the perovskite films. The solar cells employing blend systems also show nearly hysteresis-free power conversion efficiency similar to 17.5%, as well as a remarkable shelf-life stability over 100 days