The discovery of topologically nontrivial electronic systems has opened a new age in condensed matter research. From topological insulators to topological superconductors and Weyl semimetals, it is now understood that some of the most remarkable and robust phases in electronic systems (e.g., quantum Hall or anomalous quantum Hall) are the result of topological protection. These powerful ideas have recently begun to be explored also in bosonic systems. Topologically protected acoustic, mechanical, and optical edge states have been demonstrated in a number of systems that recreate the requisite topological conditions. Such states that propagate without backscattering could find important applications in communications and energy technologies. Here, a topologically bound mechanical state, a different class of nonpropagating protected state that cannot be destroyed by local perturbations, is demonstrated. It is in particular a mechanical analogue of the well-known Majorana bound states (MBSs) of electronic topological superconductor systems. The topological binding is implemented by creating a Kekulé distortion vortex on a 2D mechanical honeycomb superlattice that can be mapped to a magnetic flux vortex in a topological superconductor.

espanolEl articulo muestra los resultados obtenidos tras el estudio para la recuperacion de las bolsas biodegradables y oxodegradables una vez separadas junto a la fraccion de film convencional en la planta de seleccion y en las instalaciones de reciclado, antes de alcanzar el proceso de extrusion. El estudio se fundamenta en la hipotesis de que dichas bolsas se separaran y embalaran junto con las bolsas convencionales en planta de seleccion, debido principalmente a diversos factores tecnicos y de gestion de estos residuos. Por lo tanto, tanto las bolsas de film convencionales como las bolsas bio y oxodegradables se transportaran mezcladas a las instalaciones de reciclado de film. Las pruebas se dividieron en dos fases, la primera dirigida al analisis de la degradacion de las bolsas de estudio durante el tiempo de almacenamiento en planta de seleccion y la segunda orientada a determinar la posibilidad de recuperacion de dichas bolsas durante el proceso de limpieza y depuracion en la instalacion de reciclado. Los resultados revelan que las bolsas bio y oxodegradables estudiadas no alcanzaron la degradacion suficiente como para ser identificadas y separadas en un triaje manual tras cumplir con el periodo de almacenamiento establecido en la planta de seleccion. Igualmente, los resultados de la segunda fase mostraron que las bolsas bio y oxodegradables estudiadas apenas se separaron del flujo de lavado del film convencional a pesar de favorecer su decantacion en la balsa de lavado mediante la adaptacion del tamano del triturado del film, la turbulencia en el agua de lavado, presencia de tensioactivo y el sistema de alimentacion del film en la balsa EnglishThe article shows the results of the study of the biodegradable and oxodegradable bags recovery once they have been separated with the conventional film in the waste selection and recycling plants before the extrusion process. This study is based on the hypothesis that these bags will be separated and pressed with conventional bags in the waste selection plant due to several technical and waste management factors. Therefore, the conventional bags as well as the bio and oxodegradable ones will be transported to the recycling plants. The tests were divided in two phases. The first was aimed to analyze the bags degradation study during the storage period in waste selection plant, and the second to know the recovery possibility of the bags during the cleaning process in the recycling plant. The results showed that the bio and oxodegradable studied bags didn´t reach the enough degradation to be identified in a manual separation after the storage period. In the same way, the results of second phase revealed that, in spite of favoring the decantation in washing pool (changing the film particles size, the turbulence of washing water, the presence of surfactant and the film supply system), the studied bio and oxodegradable bags were hardly separated from conventional film washing line

The angle resolved photoemission spectroscopy lineshapes of quasi one-dimensional (1d) Li0.9Mo6O17 display both agreement with and departures from the one-band Tomonaga-Luttinger model. We show that the departures can be understood by explicitly accounting for the four modes arising from the two quasi-1d bands known to cross the Fermi energy. The key assumption is that the antisymmetric charge mode is gapped with a magnitude near the temperature (T) of a mysterious 25K powerlaw resistivity upturn. The gap is consistent with the lack of a charge or spin density wave accompanying the upturn, is able to control the upturn T, and prevents crossover to a Fermi liquid (FL) down to the superconducting transition at 1.9K.

espanolLa principal alternativa de gestion de los residuos plasticos biodegradables es el reciclado o valorizacion energetica mediante tratamiento organico. Actualmente la gestion de los bioresiduos en Espana presenta dos vias de tratamiento principales, el compostaje (condiciones aerobias) y la biometanizacion (condiciones anaerobias). En el presente estudio se analiza la biodegradabilidad de una bolsa tipo camiseta, fabricada a partir de poliester y almidon de fecula de patata, bajo condiciones de compostaje y biometanizacion, siguiendo las normas ISO 14855-1:2005 (condiciones aerobias) e ISO 15985:2004 (condiciones anaerobias). Los resultados obtenidos fueron de 75,42% tras 90 dias en compostaje y de 25,63% tras 29 dias de biometanizacion EnglishThe main alternative management of biodegradable plastic waste is recycling or energy recovering through organic processing. Currently, the management of bio-waste in Spain has two possible waste processing systems, composting (aerobic conditions) and biomethanization (anaerobic conditions). In this study, the biodegradability of a shopping bag composed of a polyester and starch potato blend under composting and biomethanization conditions is analyzed by using the standards UNE EN ISO 14855-1:2005 (aerobic conditions) and ISO 15985 : 2004 (anaerobic conditions). The results were 75,42% after 90 days in aerobic conditions and 25,63% after 29 days in anaerobic conditions

Charge fluctuations in the quasi-one-dimensional material Li0.9Mo6O17 are analyzed based on a multi orbital extended Hubbard model. A charge ordering transition induced by Coulomb repulsion is found with a charge ordering pattern different from a conventional charge density wave driven by Fermi surface nesting. The metallic state displays a characteristic charge collective mode which softens signalling the proximity to the transition. We argue that the strong scattering between electrons generated by these charge order fluctuations can lead to the unconventional metallic state observed above the superconducting transition temperature in Li0.9Mo6O17.

J. Merino1 and J. V. Alvarez2 1Departamento de Fı́sica Teórica de la Materia Condensada, Condensed Matter Physics Center (IFIMAC) and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, Madrid 28049, Spain 2Departamento de Fı́sica de la Materia Condensada, Condensed Matter Physics Center (IFIMAC) and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, Madrid 28049, Spain (Received 17 June 2014; revised manuscript received 11 January 2015; published 29 January 2015)

Control over the morphology of TiS3 is demonstrated by synthesizing 1D nanoribbons and 2D nanosheets. The nanosheets can be exfoliated down to a single layer. Through extensive characterization of the two morphologies, differences in the electronic properties are found and attributed to a higher density of sulphur vacancies in nanosheets, which, according to density functional theory calculations, leads to an n-type doping.

We present a theoretical study of the exciton binding energy for anisotropic two-dimensional crystals. We obtain analytical expressions from variational wave functions in different limits of the screening length to exciton size ratio and compare them with numerical solutions, both variational and exact. As an example, we apply these results to phosphorene, a monolayer of black phosphorous. Aided by density functional theory calculations for the evaluation of the two-dimensional polarizability, our analytical solution for the exciton binding energy gives a result which is very close to the numerical ones and, in turn, is comparable to the experimental value, as recently reported.

Superconductivity in the quasi-one-dimensional material Li0.9Mo6O17 is analyzed based on a multiorbital extended Hubbard model. We found strong charge fluctuations at two different momenta Q(1) and Q(2) giving rise to two different charge-ordered phases. Evaluating the superconducting vertex, we found superconductivity near strong charge fluctuations at Q(1). The order parameter has p-wave symmetry with nodes on the Fermi surface. The metallic state displays a characteristic charge collective mode Q(1) due to nesting and, for on-site Hubbard repulsion sufficiently large, a charge critical mode Q(2) driven by Coulomb repulsion, which softens at the proximity to the transition. The results are quite robust for different coupling parametrizations. A phase diagram discussing the relevance of the model to the physics of the material is proposed.

We calculate the electronic structure and magnetic properties of hydrogenated graphite surfaces using van der Waals density functional theory (DFT) and model Hamiltonians. We find, as previously reported, that the interaction between hydrogen atoms on graphene favors adsorption on different sublattices along with an antiferromagnetic coupling of the induced magnetic moments. On the contrary, when hydrogenation takes place on the surface of graphene multilayers or graphite (Bernal stacking), the interaction between hydrogen atoms competes with the different adsorption energies of the two sublattices. This competition may result in all hydrogen atoms adsorbed on the same sublattice and, thereby, in a ferromagnetic state for low concentrations. Based on the exchange couplings obtained from the DFT calculations, we have also evaluated the Curie temperature by mapping this system onto an Ising-like model with randomly located spins. Remarkably, the long-range nature of the magnetic coupling in these systems makes the Curie temperature size dependent and larger than room temperature for typical concentrations and sizes.

Isolation and characterization of mechanically exfoliated black phosphorus flakes with a thickness down to two single-layers is presented. A modification of the mechanical exfoliation method, which provides higher yield of atomically thin flakes than conventional mechanical exfoliation, has been developed. We present general guidelines to determine the number of layers using optical microscopy, Raman spectroscopy and transmission electron microscopy (TEM) in a fast and reliable way. Moreover, we demonstrate that the exfoliated flakes are highly crystalline and that they are stable even in free-standing form through Raman spectroscopy and TEM measurements. A strong thickness dependence of the band structure is found by density functional theory (DFT) calculations. The exciton binding energy, within an effective mass approximation, is also calculated for different number of layers. Our computational results for the optical gap are consistent with preliminary photoluminescence results on thin flakes. Finally, we study the environmental stability of black phosphorus flakes finding that the flakes are very hydrophilic and that long term exposure to air moisture etches black phosphorus away. Nonetheless, we demonstrate that the aging of the flakes is slow enough to allow fabrication of field-effect transistors with strong ambipolar behavior. DFT calculations also give us insight into the water-induced changes of the structural and electronic properties of black phosphorus.

matter. It is well recognised that water planners require a broad set of inter- contemporary water management challenges. Solving water-related problems, ability to integrate environmental, social and political considerations into planning practice. The 21st century will be an era of increased global concern regarding the availability of water. and the population in general. Despite the climate pattern has been changing continuously during the Earth s history due to changes in the atmosphere, topography, volcanic activity, and other natural factors, this change seems to have been exacerbated recently due to the alteration of the greenhouse gases content in the atmosphere by the humanity. Nowadays, the extent of this change and its warming, leaded last century by the climate change, has involved alterations in the temperature, precipitation and evaporation patters. From the point of view of