Is There a Negative Thermal Expansion in Supported Metal Nanoparticles? An In-Situ X-ray Absorption Study Coupled with Neural Network Analysis

Interactions with their support, adsorbates and unique structural motifs are responsible for the many intriguing properties and potential applications of supported metal nanoparticles (NPs). At the same time, they complicate the interpretation of experimental data. In fact, the methods and approaches that work well for the ex situ analysis of bulk materials may be inaccurate or introduce artifacts in the in situ analysis of nanomaterials. Here we revisit the controversial topic of negative thermal expansion and anomalies in the Debye temperature reported for oxide-supported metal NPs. In situ X-ray absorption experimental data collected for Pt NPs in ultrahigh vacuum and an advanced data analysis approach based on an artificial neural network demonstrate that Pt NPs do not exhibit intrinsic negative thermal expansion. Similarly as for bulk materials, in the absence of adsorbates the bond lengths in metal NPs increase with temperature. The previously reported anomalies in particle size-dependent Debye temperatures can also be linked to the artifacts in the interpretation of conventional X-ray absorption data of disordered materials such as NPs

Reptile vector-borne diseases of zoonotic concern

Reptile vector-borne diseases (RVBDs) of zoonotic concern are caused by bacteria, protozoa and viruses transmitted by arthropod vectors, which belong to the subclass Acarina (mites and ticks) and the order Diptera (mosquitoes, sand flies and tsetse flies). The phyletic age of reptiles since their origin in the late Carboniferous, has favored vectors and pathogens to co-evolve through millions of years, bridging to the present host-vector-pathogen interactions. The origin of vector-borne diseases is dated to the early cretaceous with Trypanosomatidae species in extinct sand flies, ancestral of modern protozoan hemoparasites of zoonotic concern (e.g., Leishmania and Trypanosoma) associated to reptiles. Bacterial RVBDs are represented by microorganisms also affecting mammals of the genera Aeromonas, Anaplasma, Borrelia, Coxiella, Ehrlichia and Rickettsia, most of them having reptilian clades. Finally, reptiles may play an important role as reservoirs of arborivuses, given the low host specificity of anthropophilic mosquitoes and sand flies. In this review, vector-borne pathogens of zoonotic concern from reptiles are discussed, as well as the interactions between reptiles, arthropod vectors and the zoonotic pathogens they may transmit