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The Late Cretaceous dinosaur record in southern South America has been improved recently; particularly with findings from Chorrillo and Cerro Fortaleza formations, both bearing ankylosaur remains, a clade that was not previously recorded in the Austral Basin. The dinosaur fauna of the type locality of Cerro Fortaleza Formation is known from -and biased to- large-sized sauropod remains and a single described taxon, the titanosaur Dreadnoughtus schrani. Here, we report the taxonomic composition of a site preserving thirteen isolated teeth and several osteoderms belonging to three dinosaur clades (Abelisauridae, Titanosauria, and Nodosauridae), and at least one clade of notosuchian crocodyliforms (Peirosauridae). They come from sediments positioned at the mid-section of the Cerro Fortaleza Formation, which is Campanian-Maastrichtian in age, adding valuable information to the abundance and biodiversity of this Cretaceous ecosystem. Since non-titanosaur dinosaur bones are almost absent in the locality, the teeth presented here provide a window onto the archosaur biodiversity of the Late Cretaceous in southern Patagonia. The nodosaurid tooth and small armor ossicles represent the first record of ankylosaurs for this stratigraphic unit. The peirosaurid material also represents the most austral record of the clade in South America.

Energetically unstable crystalline surfaces, among their uses, can be templates for the growth of periodic arrays of one-dimensional (1D) nanoscale structures. However, few studies have explored self-assembled faceting on high-index (HI) planes inside the stereographic triangle, and extant studies have not produced any criteria for encouraging the formation of one-dimensional periodic arrays. In this Letter, by analyzing the MBE growth of homoepitaxial facets on (631)A GaAs, a HI plane inside the triangle, we present a criteria to produce highly uniform 1D periodic arrays on unexplored surfaces. These families of planes are those belonging to the lines connecting the energetically stable HI GaAs (11 5 2) plane with any of the (100), (110), and (111) planes at the corners of the stereographic triangle. This novel strategy can lead to new possibilities in self-assembling 1D structures and manipulating physical properties, which in turn may result in new HI- and 1D-based experiments and devices.

Se realizó un estudio para determinar el comportamiento poscosecha durante su almacenamiento en raíces de 12 híbridos comerciales de zanahoria y su respectiva casa productora: Bangor F1, Nandrin F1, Napoli F1 y Norwich F1 de Bejo; Big Sur y Sirkana de Nunhems; Bolero F1 y Concerto F1 (VAC 03 F1) de Vilmorin; XCR3688 y S-505 de Sakata; Esperanza y Dulce de Seminis, cultivados en Cot de Oreamuno, Cartago. Se aplicó un tratamiento poscosecha estándar a todas las raíces de los diferentes híbridos provenientes del campo, que consistió en lavar mecánicamente mediante cepillado con agua y extracto de semillas de cítricos (Kilol L DF-100), seleccionar las raíces comerciales y pasarlas por un hidroenfriador a una temperatura de 2°C durante 15 min; luego, empacar las raíces en bolsas plásticas comerciales, para ser llevadas al laboratorio poscosecha, donde se almacenaron en una cámara fría a 2°C durante 8 semanas (56 días). Se establecieron 2 grupos de raíces pertenecientes a cada híbrido; en el primer grupo se evaluó semanalmente en diferentes raíces las variables color externo, firmeza, relación xilema/floema y contenido de sólidos solubles totales (°brix); en el segundo grupo se evaluó semanalmente en las mismas raíces las variables color externo, pérdida de peso (cambio en la masa de la raíz) e incidencia de factores de deterioro poscosecha. Se encontraron 3 tipos de daños en las raíces evaluadas: daño fisiológico, agentes patogénicos y sin agente causal conocido. El comportamiento de los materiales evaluados fue el siguiente: no hubo diferencia entre híbridos para la pérdida de peso; el color externo solo difirió en Big Sur, con respecto a los demás híbridos; XCR3688 y Bolero F1 mostraron una mayor firmeza; Bolero F1 presentó el mayor valor para grados brix. Los híbridos con el mejor comportamiento poscosecha fueron Dulce, S-505, XCR3688 y Big Sur.

Resumen: La vibración causada por el desequilibrio es un problema común que se presenta en la maquinaria rotatoria. En este artículo se presenta una revisión de los trabajos de investigación que se han realizado en el área de equilibrado y control activo de vibraciones en maquinaria rotatoria. Además, se presentan dos propuestas de solución a este problema de atenuación de vibraciones para tareas de seguimiento de trayectorias de realimentación de la salida deseada. La primera propuesta consiste en el uso de un cojinete móvil para modificar la longitud del rotor, y como consecuencia, la frecuencia natural, y así evitar las grandes amplitudes que ocurren en la resonancia. La segunda propuesta consiste en montar un disco equilibrador activo sobre el rotor, el cual contiene una masa de equilibrado que puede ubicarse en cualquier posición radial y angular dentro del disco para atenuar las vibraciones causadas por el desequilibrio residual. Puesto que ambas estrategias de control activo requieren información de la excentricidad del rotor, el método de identificación algebraica es utilizado para la estimación en línea de los valores de sus parámetros. Palabras clave: Control Activo de Vibraciones, Equilibrado Activo de Rotores, Identificación de Excentricidad

Con el propósito de evaluar el efecto de prohexadiona de calcio (P-Ca) en el contenido endógeno de giberelinas en ápices de tomate saladette (Lycopersicon esculentum Mill.) y chile pimiento (Capsicum annuum L.), se aplicaron tres dosis del retardante (125, 175 y 200 mg.litro-1) y un testigo (H2O) en ambas hortalizas en el estadio de plántula con seis hojas verdaderas. Los ápices se cosecharon los días 0, 1, 3 y 6 después de haber realizado la aplicación de los tratamientos, y las muestras se liofilizaron para su análisis en laboratorio. Se realizaron análisis cuantitativo y cualitativo de giberelinas, mediante cromatografía de gases y espectrometría de masas. Se encontró que los ápices de tomate saladette tratados con P-Ca mostraron un menor contenido de las giberelinas A4 y A7 a partir del siguiente día de haberse aplicado los tratamientos. Esta tendencia fue consistente hasta el sexto día de evaluación. Resultados similares se registraron con los ápices de chile pimiento. Los análisis de cromatografía de gases y espectrometría de masas, permitieron identificar en ápices tratados con P-Ca la giberelina A20 en tomate saladette, mientras que las giberelinas A20 y A53 estuvieron presentes en chile pimiento. En los ápices testigo de ambas hortalizas, se encontraron las giberelinas A1, A4 y A7.

Amorphous carbon nitride films with N/C ratios ranging from 2.24 to 3.26 were deposited by reactive sputtering at room temperature on corning glass, silicon, and quartz as substrates. The average chemical composition of the films was obtained from the semiquantitative energy dispersive spectroscopy analysis. Photoluminescence measurements were performed to determine the optical band gap of the films. The photoluminescence spectra displayed two peaks: one associated with the substrate and the other associated with CNx films located at ≈2.13±0.02 eV. Results show an increase in the optical band gap from 2.11 to 2.15 eV associated with the increase in the N/C ratio. Raman spectroscopy measurements showed a dominant D band. ID/IG ratio reaches a maximum value for N/C ≈ 3.03 when the optical band gap is 2.12 eV. Features observed by the photoluminescence and Raman studies have been associated with the increase in the carbon sp2/sp3 ratio due to presence of high nitrogen content.

Photoreflectance (PR) and Raman are two very useful spectroscopy techniques that usually are used to know the surface electronic states in GaAs-based semiconductor devices. However, although they are exceptional tools there are few reports where both techniques were used in these kinds of devices. In this work, the surface electronic states on AlGaAs/GaAs heterostructures were studied in order to identify the effect of factors like laser penetration depth, cap layer thickness, and surface passivation over PR and Raman spectra. PR measurements were performed alternately with two lasers (532 nm and 375 nm wavelength) as the modulation sources in order to identify internal and surface features. The surface electric field calculated by PR analysis decreased whereas the GaAs cap layer thickness increased, in good agreement with a similar behavior observed in Raman measurements (IL-/ILO ratio). When the heterostructures were treated by Si-flux, these techniques showed contrary behaviors. PR analysis revealed a diminution in the surface electric field due to a passivation process whereas the IL-/ILO ratio did not present the same behavior because it was dominated by the depletion layers width (cap layer thickness) and the laser penetration depth.

In this letter, self-switching nanochannels have been proposed as an enabling technology for energy gathering in the terahertz (THz) regime. Such devices combine their diode-like behavior and high-speed of operation in order to generate DC electrical power from high-frequency signals. By using finite-element simulations, we have improved the sensitivity of L-shaped and V-shaped nanochannels based on InAlAs/InGaAs samples. Since those devices combine geometrical effects with their rectifying properties at zero-bias, we have improved their performance by optimizing their shape. Results show nominal sensitivities at zero-bias in the order of 40 V−1 and 20 V−1, attractive values for harvesting applications with square-law rectifiers.

The first bony theropod record from the Campanian Uberaba Formation (Bauru Group) is described. It consists of an isolated caudal centrum (CPPLIP 1324) found in the city of Uberaba, Minas Gerais State, Brazil. The amphicoelous centrum possesses a length to height ratio of 1.74, deep elliptical lateral pneumatic foramen representing 26% of centrum length with three main sub-circular air chambers, andcamellate internal structure.This combination of features is shared with Aerosteon, Megaraptor, and Orkoraptor from the Late Cretaceous of Argentinaand with the Megaraptora indet. fromthe São José do Rio Preto Formation (Bauru Group), São Paulo State,allowing us to refer it to the Megaraptora clade (Tetanurae, Neovenatoridae). As such, the new specimen represents the second megaraptoran from the Late Cretaceous of Brazil and provides new information on tail anatomy on this bizarre group.

A damage model with different failure surface in tension and compression is formulated, implemented and validated to study reinforced concrete elements under actions which induce their collapse. The constitutive behaviour of concrete considers the softening deformation after reaching a failure surface, whereas the hardening of the reinforcing steel is represented by a plasticity von Mises surface. The developed damage model does not exhibit the problem of stress locking as the smeared cracking model does; this guaranties an adequate energy release as the material fails. Numerical examples are presented showing the validity of the developed damage model for modelling the behaviour of reinforced concrete elements up to their collapse.