Infinite charge mobility in muscovite at 300K

Evidence is presented for infinite charge mobility in natural crystals of muscovite mica at room temperature. Muscovite has a basic layered structure containing a flat monatomic sheet of potassium sandwiched between mirror silicate layers. It is an excellent electrical insulator. Studies of defects in muscovite crystals indicated that positive charge could propagate over great distances along atomic chains in the potassium sheets in absence of an applied electric potential. The charge moved in association with anharmonic lattice excitations that moved at about sonic speed and created by nuclear recoil of the radioactive isotope K40. This was verified by measuring currents passing through crystals when irradiated with energetic alpha particles at room temperature. The charge propagated more than 1000 times the range of the alpha particles of average energy and 250 times the range of channelling particles of maximum energy. The range is limited only by size of the crystal.Comment: 6 pages, 8 figure

Cinemómetro piezoeléctrico de alta exactitud (VUAE)

Se ha desarrollado un sistema electrónico computerizado, portátil y de bajo consumo, denominado Medidor de Velocidad de Vehículos por Ultrasonidos de Alta Exactitud, VUAE. La alta exactitud de la medida conseguida en el VUAE hace que pueda servir de medida de referencia de la velocidad de un vehículo circulando en carretera. Por tanto el VUAE puede usarse como medida de referencia que permita estimar el error de los cinemómetros comerciales. El VUAE está compuesto por n (n≥2) parejas de emisores y receptores piezoeléctricos de ultrasonidos, denominados E-Rult. Los emisores de las n parejas E-Rult generan n barreras de ultrasonidos, y los receptores piezoeléctricos captan la señal de los ecos cuando el vehículo atraviesa las barreras. Estos ecos se procesan digitalmente para conseguir señales representativas. Posteriormente, utilizando la técnica de la correlación cruzada de señales, se ha podido estimar con alta exactitud la diferencia de tiempos entre los ecos captados en cada barrera. Con los tiempos entre ecos y con la distancia entre cada una de las n barreras de ultrasonidos se puede realizar una estimación de la velocidad del vehículo con alta exactitud. El VUAE se ha contrastado con un sistema de velocidad de referencia, basado en cables piezoeléctricos.Peer reviewe

El turismo micológico como fuente de ingresos y empleo en el medio rural. El caso de Castilla y León

Edible wild mushroom picking is becoming an important source of income in rural areas. The wide range of activitieswhich add value to mycological production (initial sale, transformation, marketing, etc.) include those related to tourismwhich can attract visitors to mushroom producing areas, leading to so-called mycological tourism. To date, no researchexists quantifying the importance thereof in rural areas endowed with such resources. The present research provides thefirst model to estimate this activity’s contribution to the economy of rural areas in the region of Castilla y León. The mainfinding to emerge evidences a close link between influx of visitors, who come principally to pick, and mycological productivityin the region. Based on this relation, we estimate four key variables to determine the impact which said activityhas on the regional economy as a whole: the number of overnight stays and trips made by mycological tourists, as wellas associated expenditure and employment created. Findings underscore the importance of this activity in the regionaltourism industry and point to its significance as a major market niche, particularly during the hotel low season. The needfor public administrators to implement a related management policy is also inferred. La recolección de hongos silvestres comestibles se está convirtiendo en un importante motor generador de rentasen el medio rural. Entre las variadas actividades que aportan valor a la cadena de producción, relacionadas con la micología (primera venta, transformación, comercialización, etc.), se encuentran aquellas de turismo capaces de atraer visitantes a los territorios productores o turismo micológico. En la actualidad no existe ninguna investigación que cuantifique su importancia en las áreas rurales con recurso. Así, en la presente investigación se desarrolla por primera vez un modelo, que se aplica para estimar esta aportación a la economía de los territorios rurales de la comunidad autónoma de Castilla y León. El principal hallazgo obtenido muestra que existe una fuerte relación entre afluencia de visitantes, cuya principal motivación es recolectar, y la productividad micológica del territorio. A partir de esta relación se estiman cuatro variables fundamentales para calcular la importancia de esta actividad en el total de esta economía: el número de pernoctaciones y de viajes realizados por turistas micológicos, así como el gasto asociado y el empleo generado. Los resultados expuestos muestran la importancia relativa de esta actividad sobre el sector del turismo rural en la región, lo que la convierte en un importante nicho de mercado de vital importancia, sobre todo en temporadas de baja ocupación de los establecimientos hoteleros, lo que hace necesario políticas de gestión de esta actividad por parte de las administraciones públicas.

Solvent-free lipase-catalyzed synthesis of diacylgycerols as low-calorie food ingredients

Problems derived from obesity and overweight have recently promoted the development of fat substitutes and other low-calorie foods. On the one hand, fats with short- and medium-chain fatty acids are a source of quick energy, easily hydrolyzable and hardly stored as fat. Furthermore, 1,3-diacylglycerols are not hydrolyzed to 2-monoacylglycerols in the gastrointestinal tract, reducing the formation of chylomicron and lowers the serum level of triacylglycerols by decreasing its resynthesis in the enterocyte. In this work, these two effects were combined to synthesize short- and medium-chain 1,3-diacylglycerols, leading to a product with great potential as for their low-calorie properties. Lipase-catalyzed transesterification reactions were performed between short- and medium-chain fatty acid ethyl esters and glycerol. Different variables were investigated, such as the type of biocatalyst, the molar ratio FAEE:glycerol, the adsorption of glycerol on silica gel, or the addition of lecithin. Best reaction conditions were evaluated considering the percentage of 1,3-DAG produced and the reaction rate. Except Novozym 435 (Candida antarctica), other lipases required the adsorption of glycerol on silica gel to form acylglycerols. Lipases that gave the best results with adsorption were Novozym 435 and Lipozyme RM IM (Rhizomucor miehei) with 52 and 60.7% DAG at 32h, respectively. Because of its specificity for sn-1 and sn-3 positions, lipases leading to a higher proportion of 1,3-DAG vs. 1,2-DAG were Lipozyme RM IM (39.8 and 20.9%, respectively) and Lipase PLG (Alcaligenes sp.) (35.9 and 19.3%, respectively). By adding 1% (w/w) of lecithin to the reaction with Novozym 435 and raw glycerol, the reaction rate was considerably increased from 41.7 to 52.8% DAG at 24h.This work was supported by the Comunidad Autónoma de Madrid: ALIBIRD, project number S2013/ABI-2728.Peer Reviewe

Reference frames in General Relativity and the galactic rotation curves

The physical interpretation of the exact solutions of the Einstein field equations is, in general, a challenging task, part of the difficulties lying in the significance of the coordinate system. We discuss the extension of the International Astronomical Union (IAU) reference system to the exact theory. It is seen that such an extension, retaining some of its crucial properties, can be achieved in a special class of spacetimes, admitting non-shearing congruences of observers which, at infinity, have zero vorticity and acceleration. As applications, we consider the FLRW, Kerr and NUT spacetimes, the van Stockum rotating dust cylinder, spinning cosmic strings and, finally, we debunk the so-called Balasin-Grumiller (BG) model, and the claims that the galaxies' rotation curves can be explained through gravitomagnetic effects without the need for Dark Matter. The BG spacetime is shown to be completely inappropriate as a galactic model: its dust is actually static with respect to the asymptotic inertial frame, its gravitomagnetic effects arise from unphysical singularities along the axis (a pair of NUT rods, combined with a spinning cosmic string), and the rotation curves obtained are merely down to an invalid choice of reference frame -- the congruence of zero angular momentum observers, which are being dragged by the singularities.Comment: 29 pages, 10 figures. Slightly improved version, typos corrected, references added. Supplemental material is provided in the ancillary Mathematica files "NUTmetrics.nb" and "BGmetric.nb". Version to be submitte

(5RS,10SR,15RS)-Trimethyl­truxene1

The title mol­ecule, C30H24, was prepared as a possible precursor to buckminsterfullerene cages. The two enanti­omers adopt the anti configuration, with one S/R and two R/S methyl groups, one anti to the other two. The truxene framework is slightly non-planar: with respect to the central six-ring mean plane, the three methyl C atoms are 1.377 (3), −1.475 (3) and 1.515 (3) Å distant, whereas the respective proximate peripheral six-ring mean planes make dihedral angles of 6.27 (6), 3.45 (7) and −7.37 (7)°