RESUMEN
Atomically thin group IV monochalcogenides or phosphorene analogues are a promising family of materials. Theoretical calculations predict that monolayers should be semiconducting, ferroelectric and ferroelastic at room temperature, exhibit large charge mobilities and large non-linear optical response. Yet, experimental studies of these systems are scarce because of the difficulty to produce such monolayers. Here we focus on two members of this family: GeSe and SnS. We demonstrate a simple mechanical exfoliation method to produce monolayer samples on gold substrates. We observe the evolution of the Raman scattering as a function of layers and the anisotropic optical response from reflectance contrast measurements. To the best of our knowledge this is the first report of mechanical exfoliation down to the monolayer of these materials and the first realisation of monolayer GeSe. .
RESUMEN
Bartonella genus includes an increasing number of species and subspecies, especially among wild felids, the positioning of which, with regards to the zoonotic species Bartonella henselae, is important to determine. The aim of this study was to test the ability of a molecular typing technique to distinguish between various Bartonella isolates obtained from four different species of free-ranging and captive wild felids and to identify key profiles or markers allowing differentiating them from each other and/or from B. henselae or B. koehlerae. A molecular typing technique for B. henselae based on the polymorphism of variable number tandem repeat units (VNTR) called MLVA (Multiple Locus VNTR Analysis) was applied to 24 Bartonella isolates from free-ranging or captive wild felids, 19 of which were obtained from California and five from three countries in Southern Africa, and compared with 49 B. henselae isolates from cats, dog or humans from the United States including the human ATCC (American Type Culture Collection) reference strain, B. henselae Houston 1. MLVA allowed distinguishing Bartonella isolates from wild felids from either B. henselae or B. koehlerae. We confirmed infection of semi-captive cheetahs with an isolate similar to a Californian bobcat isolate. MLVA also confirmed the unique profile of a free-ranging cheetah isolate from Namibia. Specific profiles were observed making MVLA a useful identification/classification tool of these wild felid isolates and suggesting that they are highly adapted to a specific feline reservoir. Finally, circulation of B. henselae isolates between domestic cats, wild felids and humans is likely occurring, based on the close allelic profiles of some isolates.
