Combined grazing incidence RBS and TEM analysis of luminescent nano-SiGe/SiO2 multilayers.

Multilayer structures with five periods of amorphous SiGe nanoparticles/SiO2 layers with different thickness were deposited by Low Pressure Chemical Vapor Deposition and annealed to crystallize the SiGe nanoparticles. The use of grazing incidence RBS was necessary to obtain sufficient depth resolution to separate the signals arising from the individual layers only a few nm thick. The average size and areal density of the embedded SiGe nanoparticles as well as the oxide interlayer thickness were determined from the RBS spectra. Details of eventual composition changes and diffusion processes caused by the annealing processes were also studied. Transmission Electron Microscopy was used to obtain complementary information on the structural parameters of the samples in order to check the information yielded by RBS. The study revealed that annealing at 900 °C for 60 s, enough to crystallize the SiGe nanoparticles, leaves the structure unaltered if the interlayer thickness is around 15 nm or higher

Security assessment of the Spanish contactless identity card

The theft of personal information to fake the identity of a person is a common threat normally performed by individual criminals, terrorists, or crime rings to commit fraud or other felonies Recently, the Spanish identity card, which provides enough information to hire online products such as mortgages or loans, was updated to incorporate a near-field communication chip as electronic passports do. This contactless interface brings a new attack vector for criminals, who might take advantage of the radio-frequency identification communication to virtually steal personal information. In this study, the authors consider as case study the recently deployed contactless Spanish identity card assessing its security against identity theft. In particular, they evaluated the security of one of the contactless access protocol as implemented in the contactless Spanish identity card, and found that no defences against online brute-force attacks were incorporated. They then suggest two countermeasures to protect against these attacks. Furthermore, they also analysed the pseudo-random number generator within the card, which passed all the performed tests with good results

Organic cheese market (Río Cuarto, Argentina). Consumer attitudes

The consumer attitudes and buying behaviour to ecological cheese, in Río Cuarto city were studied. This research was carried out as a semi -structured survey, based on personal interviews and taste panels. Forty-four percent of the consumers showed willingness to pay up to a 25 to 35 percent premium price for organic foods. Flavour and ecological nature of the product were the chief motivations for buying behaviour.Se estudió mediante encuestas semiestructuradas, la actitud de los consumidores respecto a un queso ecológico y su valoración, en la ciudad de Río Cuarto. El 44 p.100 de los consumidores manifestó intención de pagar desde un 25 a 35 p.100 de sobreprecio por el producto ecológico. Entre las principales motivaciones para la compra están el sabor (91 p.100) y la naturaleza ecológica del producto (81 p.100)

Tent-roosting may have driven the evolution of yellow skin coloration in Stenodermatinae bats

The recent discovery of the first mammal that deposits significant amounts of carotenoid pigments in the skin (the Honduran white bat Ectophylla alba) has highlighted the presence of conspicuous yellow coloration in the bare skin of some bats. This is patent in the subfamily Stenodermatinae, where many species build tents with plant leaves for communal roosting at daytime. On the basis that tents offer rich light conditions by partly allowing sunlight to pass through the leaves and this makes that yellow coloration probably provides camouflage benefits to tent-roosting bats, that gregariousness facilitates visual communication, and that all Stenodermatinae bats possess retinal L-cones that allow the perception of long-wavelength light and have a frugivorous diet from which carotenoids are obtained, we hypothesized that tent-roosting may have driven the evolution of yellow skin coloration in this group of bats. We tested this prediction in 71 species within Stenodermatinae. Reconstructions of ancestral states showed that the common ancestor was most likely not colorful and did not roost in tents, but both traits early appeared in the first phylogenetic ramification. Phylogenetically controlled analyses showed that, as predicted, yellow skin coloration and tent-roosting coevolved after their appearance. This is the first explanation for the evolution of body coloration in nocturnal mammals. As the light environment of nocturnal forests is dominated by yellow-green wavelengths that coincide with the spectral sensitivity of some bats, nocturnal light conditions may have acted jointly with diurnal light conditions in tents to favor the evolution of yellow skin coloration in these animals

The behavior of kinetic parameters in production of pectinase and xylanase by solid-state fermentation

AbstractSolid-state fermentation (SSF) is defined as the growth of microbes without a free-flowing aqueous phase. The feasibility of using a citrus peel for producing pectinase and xylanase via the SSF process by Aspergillus niger F3 was evaluated in a 2kg bioreactor. Different aeration conditions were tested to optimize the pectinase and xylanase production. The best air flow intensity was 1VkgM (volumetric air flow per kilogram of medium), which allowed a sufficient amount of O2 for the microorganism growth producing 265U/g and 65U/g pectinases and xylanases, respectively. A mathematical model was applied to determine the different kinetic parameters related to SSF. The specific growth rate and biomass oxygen yield decreased during fermentation, whereas an increase in the maintenance coefficient for the different employed carbon sources was concurrently observed

Aportación al estudio micosociológico de la provincia de León

Se muestran los resultados de algunas excursiones y el catálogo de las especies de macromicetes recolectadas en cada localidad.We show the results of some excursions with the catalogue of species rellected in each place

Avances en la investigación con Andropogon gayanus y Brachiaria decumbens en los Llanos Orientales de Colombia.

Ganado de carne-Ganadería carn