Current rectification in a single molecule diode: the role of electrode coupling

We demonstrate large rectification ratios (> 100) in single-molecule junctions based on a metal-oxide cluster (polyoxometalate), using a scanning tunneling microscope (STM) both at ambient conditions and at low temperature. These rectification ratios are the largest ever observed in a single-molecule junction, and in addition these junctions sustain current densities larger than 10^5 A/cm^2. By following the variation of the I-V characteristics with tip-molecule separation we demonstrate unambiguously that rectification is due to asymmetric coupling to the electrodes of a molecule with an asymmetric level structure. This mechanism can be implemented in other type of molecular junctions using both organic and inorganic molecules and provides a simple strategy for the rational design of molecular diodes

Giant Gastroduodenal Duplication Cyst with Juxta-Pancreatic Communication

Enteric duplication cysts are rare congenital malformations with a low incidence and there are only a few reports in the literature. Their clinical presentation varies according to the location and the type of duplication. T heir overall prognosis is good if early surgical intervention is provided. We report a 2-month-old boy who presented with a case of a giant gastroduodenal duplication cyst with a juxta-pancreatic communication and was successfully treated surgically. It is imperative to be aware of this rare congenital malformation that can present clinically with a wide range of non-specific symptoms that can cause significant morbidity and mortality if the treatment is delayed

Testing particle trapping in transition disks with ALMA

We present new Atacama Large Millimeter/submillimeter Array (ALMA) continuum observations at 336GHz of two transition disks, SR21 and HD135344B. In combination with previous ALMA observations from Cycle 0 at 689GHz, we compare the visibility profiles at the two frequencies and calculate the spectral index ($\alpha_{\rm{mm}}$). The observations of SR21 show a clear shift in the visibility nulls, indicating radial variations of the inner edge of the cavity at the two wavelengths. Notable radial variations of the spectral index are also detected for SR21 with values of $\alpha_{\rm{mm}}{\sim}3.8-4.2$ in the inner region ($r<35$ AU) and $\alpha_{\rm{mm}}{\sim}2.6-3.0$ outside. An axisymmetric ring (which we call the ring model) or a ring with the addition of an azimuthal Gaussian profile, for mimicking a vortex structure (which we call the vortex model), is assumed for fitting the disk morphology. For SR21, the ring model better fits the emission at 336GHz, conversely the vortex model better fits the 689GHz emission. For HD135344B, neither a significant shift in the null of the visibilities nor radial variations of $\alpha_{\rm{mm}}$ are detected. Furthermore, for HD135344B, the vortex model fits both frequencies better than the ring model. However, the azimuthal extent of the vortex increases with wavelength, contrary to model predictions for particle trapping by anticyclonic vortices. For both disks, the azimuthal variations of $\alpha_{\rm{mm}}$ remain uncertain to confirm azimuthal trapping. The comparison of the current data with a generic model of dust evolution that includes planet-disk interaction suggests that particles in the outer disk of SR21 have grown to millimetre sizes and have accumulated in a radial pressure bump, whereas with the current resolution there is not clear evidence of radial trapping in HD135344B, although it cannot be excluded either.Comment: Minor changes after language edition. Accepted for publication in A&A (abstract slightly shortened for arXiv

Opciones de productos a partir de la madera de acacia y su promoción : antecedentes de una experiencia con acacias en Chile

La investigación desarrollada por el Instituto Forestal (INFOR) ha generado la base para aprovechar la adaptabilidad que presentan en el país Acacia dealbata, Acacia mearnsii y A. melanoxylon, y su explotación como especies forestales alternativas para la producción de madera. Se ha investigado en las propiedades y aptitudes físico-mecánicas y pulpables de las especies para su uso en la industria del aserrío, tableros, pulpa y papel, y la identificación de las variables que inciden en el porcentaje de taninos obtenibles a partir de la corteza de A. mearnsii que crece en Chile. Este trabajo resume los resultados de la investigación emprendida por INFOR durante el desarrollo de los estudios referidos a los procesos industriales y aplicaciones de la madera.____________________________________Research studies carried out at Instituto Forestal (INFOR) have provided the basis for exploiting the adaptability of Acacia dealbata, A. mearnsii y A. melanoxylon to Chilean environments and its exploitation as an alternative forest species for wood production. The information has been generated about the properties and physical-mechanical aptitudes and pulpables of the species for its use in the industry of the Sawed wood, boards, pulp and paper, and the identification of the variables that impact in the percentage of attainable tannins starting from the bark of A. mearnsii in Chile. This work summarizes the results of the investigation undertaken by INFOR during the development of the studies referred to the industrial processes and applications of the wood

El diseño significativo

Este texto propone el desarrollo de un proceso de diseño enfocado en la integración de las disciplinas del diseño industrial y la terapia ocupacional. Plantea estrategias en un proyecto de diseño, para que los profesionales puedan aplicar sus conocimientos en el momento justo. Establece relaciones de contenidos desde las dos disciplinas: La complejidad funcional y las funciones indicativas de los objetos son significativas si se basan en el estudio del subsistema de desempeño de funciones de la ocupación humana. Igualmente el subsistema de habituación de la ocupación humana complementa las funciones simbólicas de los objetos. Finalmente, expone la significación del diseño basado en el desarrollo y la potenciación de las capacidades alternativas de las personas y cómo al tomarlas como insumos del proceso, en conjunto con la motivación de las personas, se pueden convertir en recursos para el diseño

Relative Radiometric Normalization of Multitemporal images

A correct radiometric normalization between both images is fundamental for change detection. MAD method and its IR-MAD extension in an implementation on multisprectral aerial images is described in this paper

Recovery of betulinic acid from plane tree (Platanus acerifolia L.)

Betulinic acid (3β, hydroxy-lup-20(29)-en-28-oic acid) is a bioactive triterpenic acid which was identified in various botanical sources and in considerable amounts in the bark of plane tree (Platanus acerifolia L.). In this work, the recovery of betulinic acid from plane tree bark was studied using different liquid solvent based extraction methods, namely solid-liquid extraction (SLE), ultrasound assisted extraction (UAE) and pressurized liquid extraction (PLE). Furthermore, preliminary studies of the supercritical fluid extraction (SFE) of plane tree bark are also reported. The liquid solvent based extraction techniques (SLE, UAE and PLE) were carried out using ethanol and ethyl acetate, and produced a recovery of betulinic acid in the range 10-15 mg/g of bark, with concentrations around 25-35% mass. A betulinic acid enrichment in the ethanolic extracts was possible by means of a simple precipitation step adding water. The precipitate contained 42-46% mass of betulinic acid and high recovery (>95%). Increasing the extraction temperature, by means of the PLE assays, has not resulted in an improvement of betulinic acid recovery. The preliminary SFE assays produced lower recoveries of betulinic acid (0.5-8 mg/g) with respect to liquid extraction. The addition of ethanol as cosolvent produced a significant improvement of both betulinic acid recovery and concentration in the SFE extract.This work has been supported by project ALIBIRD-S2009/AGR-1469 from Comunidad Autónoma de Madrid. López-Padilla A. thanks to COLCIENCIAS (568–2012) and Medellin Mayor's Office (Sapiencia/Enlaza Mundos Program, 2013) for the Ph.D. fellowship.Peer Reviewe

Monoclonal Gammopathy of Undetermined Significance Disguised as Chronic Neutrophilic Leukemia

We encountered a 60-year-old woman with a medical history of diabetes mellitus, osteoporosis, peripheral vascular disease, and hypertension who had earlier presented at an outside facility with knee pain, which led to a finding of elevated neutrophil count of 35×109/L. Because she was otherwise asymptomatic but continued showing elevated neutrophil levels, she sought a second opinion at our facility. Serum protein immunoelectrophoresis with immunofixation revealed an immunoglobulin A (IgA)-κ monoclonal gammopathy concentration of 1305 mg/dL (normal 80–350 mg/dL) but relatively normal concentrations of IgG of 840 mg/dL (620–1400 mg/dL) and IgM of 36 mg/dL (45–250 mg/dL). Using clonal analysis, we found a polyclonal expression pattern in all cell types analyzed. Comprehensive work-up for multiple myeloma and infectious etiology of neutrophilia was negative. We concluded that our patient’s neutrophilia may have been due to the underlying monoclonal gammopathy. This is the first case in the literature of a patient with monoclonal gammopathy of undetermined significance presenting with chronic neutrophilia, mimicking chronic neutrophilic leukemia (CNL). Patients with CNL have a poor prognosis; therefore, it is important to distinguish diagnostically between CNL and reactive neutrophilia

JWST observations of stellar occultations by solar system bodies and rings

In this paper we investigate the opportunities provided by the James Webb Space Telescope (JWST) for significant scientific advances in the study of solar system bodies and rings using stellar occultations. The strengths and weaknesses of the stellar occultation technique are evaluated in light of JWST's unique capabilities. We identify several possible JWST occultation events by minor bodies and rings, and evaluate their potential scientific value. These predictions depend critically on accurate a priori knowledge of the orbit of JWST near the Sun-Earth Lagrange-point 2 (L2). We also explore the possibility of serendipitous stellar occultations by very small minor bodies as a by-product of other JWST observing programs. Finally, to optimize the potential scientific return of stellar occultation observations, we identify several characteristics of JWST's orbit and instrumentation that should be taken into account during JWST's development.Comment: This paper is one of a series for a special issue on Solar System observations with JWST in PASP. Accepted 2-Oct-2015. Preprint 30 pages, 5 tables, 8 figure

Double quantum dot with tunable coupling in an enhancement-mode silicon metal-oxide semiconductor device with lateral geometry

We present transport measurements of a tunable silicon metal-oxide-semiconductor double quantum dot device with lateral geometry. Experimentally extracted gate-to-dot capacitances show that the device is largely symmetric under the gate voltages applied. Intriguingly, these gate voltages themselves are not symmetric. Comparison with numerical simulations indicates that the applied gate voltages serve to offset an intrinsic asymmetry in the physical device. We also show a transition from a large single dot to two well isolated coupled dots, where the central gate of the device is used to controllably tune the interdot coupling.Comment: 4 pages, 3 figures, to be published in Applied Physics Letter