THz-conductivity of CVD graphene on different substrates

Optoelectronic properties of CVD graphene are charac-terized over a wide frequency range: THz, IR, visible and near-UV. We used Raman spectroscopy to characterize the synthesized graphene films. All graphene layers were deposited on various substrates, some ones transparent or flexible, such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), quartz and silicon. Transmission Terahertz time-domain spectroscopy (THz-TDS) method, in the range from 100 GHz to 3 THz, is used to analyze the transmittance, sheet conductivity and attenuation of graphene and the complex refractive index of substrates. From IR, near-UV and visible spectroscopy we obtained the transmittance of the substrate and the sample at those frequency ranges, and we deduced the graphene transmittance on each substrate. We found that it is close to 97% in most cases.Peer ReviewedPostprint (published version

A statistical analysis of nanocavities replication applied to injection moulding

The purpose of this paper is to investigate both theoretically and experimentally how nanocavities are replicated in the injection moulding manufacturing process. The objective is to obtain a methodology for efficiently replicate nanocavities. From the theoretical point of view, simulations are carried out using a submodeling approach combining Solidworks Plastics for a first macrosimulation and Fluent solver for a subsequent nanosimulation. The effect of the four main factors (melt temperature, mould temperature, filling time and cavity geometry) are quantified using an statistical 2 factorial experiment. It is found that the main effects are the cavity length, the mould temperature and the polymer temperature, with standardized effects of 5, 3 and 2.6, respectively. Filling time has a negative 1.3 standardized effect. From the experimental point of view, Focused Ion Beam technique is used for mechanizing nanocavities in a steel mould. The replication achieved in polycarbonate injection is quantified using an Atomic Force Microscope. It is observed how both the geometry and the position of the cavities in the mould affect its replication

Replication of nanoscale surface gratings via injection molding

Nanostructured gratings fabricated on silicon chips have been successfully transferred to polypropylene plastic parts by means of injection molding. Different sets of experiments were carried out along with a repeatability analysis in order to study the effect in the replication of process parameters such as maximum injection pressure, injection time, charge and polymer temperature, geometric factors such as width and separation between lines of the gratings and flow direction as well as demolding conditions. Among all factors, the one with a larger effect is the separation between consecutive trenches, which was studied in detail through Computational Fluid Dynamics simulations. In addition, a previously not reported sinking effect in the nanostructured area and a shrinking of the pattern period were characterized and simulated

Improved adhesion and tribological properties of altin-tisin coatings deposited by dcms and hipims on nitrided tool steels

Hard coatings, such as AlTiN-TiSiN, deposited by Physical Vapor Deposition (PVD) techniques are widely used in industrial applications to protect and increase the lifetime of industrial components, such as cutting tools, dies, and forming tools. Despite their great properties, such as high hardness and wear and oxidation resistance, they are limited in cases of severe conditions due to the poor adhesion between the coating and the substrate. Duplex treatments have commonly been used to improve the adhesive properties of PVD coatings, especially those of the cathodic arc evaporation type. The purpose of this study is to achieve coatings with the good properties of the Magnetron Sputtering processes but with higher adhesion than that achieved with these techniques, thus achieving coatings that can be used under the most severe conditions. In this work, an AlTiN-TiSiN coating was deposited by a combination of DC Magnetron Sputtering (DCMS) and High-Power Impulse Magnetron Sputtering (HiPIMS) after a gas nitriding pretreatment on 1.2379 and Vanadis 4 tool steels. Mechanical (ultra-microhardness and scratch tests) and tribological tests were carried out to study the improvement in the properties of the coating. Duplex-treated samples showed improved adhesion between the coating and the substrate, with second critical load (Lc2) values greater than 100 N. Furthermore, they showed great toughness and wear resistance. These results show that this type of coating technique could be used in the most extreme applications and that they can compete with other techniques and coatings that to date they have not been able to compete with.This research was funded in part by the Spanish Ministry of Science, Innovation and Universities through grants PGC2018-096855-B-C43 and PGC2018-096855-A-C44

Facilitant la vida a l'editor de Drupal

Un CMS és una plataforma que ens permet publicar i gestionar continguts, a més depublicar-los a internet. És una forma pràctica de gestionar una pàgina web, fer-la flexible, dinàmica, automàtica i sense necessitat de programar-la des de zero. Drupal és un CMS, i un dels grans handicaps que té és la seva dificultat a l'hora de ser "user-friendly", a més de ser força complexe a l'hora de desenvolupar una web en comparació a altres CMS. Però això, no té perquè ser del tot així, és pot adaptar la plataforma per fer-la més amigable i fàcil, per aquells que no puguin dedicar moltes hores en aprendre el funcionament de la plataforma i perdre's pels menús sense saber com utilitzar el CMS.Un CMS es una plataforma que nos permite publicar y gestionar contenidos, además de publicarlos en internet. Es una forma práctica de gestionar una página web, hacerla flexible, dinámica, automática y sin necesidad de programarla desde cero. Drupal es un CMS, y uno de los grandes handicaps que tiene es su dificultad a la hora de ser "user-friendly", además de ser bastante complexe a la hora de desarrollar una web en comparación a otras CMS. Pero esto, no tiene porque ser del todo así, es puede adaptar la plataforma para hacerla más amigable y fácil, por aquellos que no puedan dedicar muchas horas al aprender el funcionamiento de la plataforma y perderse por los menús sin saber como utilizar el CMS.A CMS is a platform that allows us to publish and manage content, also publishing them on the internet. It is a practical way to manage a web page, make it flexible, dynamic, automatic and without needing to program from scratch. Drupal is a CMS, and one of the biggest handicaps it has is that is not very "userfriendly", as well as being quite complex when it comes to web developing, compared to other CMS. But this dosn't have to be the case, the platform can be adapted to make it more user-friendly and easy to use, for those who can not devote much time into learning how it works at all levels the CMS (Drupal)

Síntesis y aplicación de homocompuestos de TiO2 a la eliminación de contaminantes

Existen ciertos problemas de ingeniería para el uso generalizado de reacciones fotocatalíticas. La utilización de catalizadores en forma de partículas es el mayor causante de opacidad en el medio y ademas, una vez terminado el proceso es difícil de separar del medio de reacción. La solución a estos problemas pasa por la deposición del fotocatalizador sobre sustratos soporte. Esta deposición provoca una gran disminución de la superficie específica del fotocatalizador con la consiguiente disminución de su actividad. Con el fin de solucionar la problemática que existe en los procesos industriales que usan fotocatalizadores depositados sobre sustratos, se ha sintetizado una película compuesta por partículas con actividad fotocatalitica de TiO2 unidas al sustrato mediante una pelicula tambíen de TiO2 obteniendose un material homocompuesto, es decir, un material compuesto por dos formas distintas del mismo compuesto químico. De este modo se consigue un material transparente con actividad fotocatalítica susceptible de ser utilizado industrialmente. Se ha demostrado la actividad fotocatalítica del material homocompuesto realizando la destrucción de modelos de contaminantes tanto en fase acuosa como en fase vapor

Aplicación de los análisis de ADN antiguo e isótopos estables en arqueozoología

En los últimos años los análisis de ADN y de isótopos estables se han incorporado de manera sistemática a la investigación arqueológica. Estas aplicaciones han supuesto un cambio radical en las posibilidades de la Arqueozoología y en la propia concepción de la representatividad histórica de los conjuntos faunísticos. Los análisis paleomoleculares conllevan una serie de ventajas respecto a las metodologías y técnicas que tradicionalmente se vienen utilizando en Arqueozoología. La primera es la posibilidad de incidir directamente en la dinámica y régimen de vida de las poblaciones animales vivas (caracterización de las estrategias de reproducción, alimentación y movilidad a que se ven sometidas), hecho hasta ahora prácticamente imposible a partir de los procedimientos tradicionales. La segunda ventaja contempla la posibilidad de ampliar de manera significativa la resolución temporal de las muestras con las que se trabaja, permitiendo estudiar y analizar las dinámicas históricas a escalas temporales significativamente reducidas, característica que ha permitido incidir en determinados aspectos hasta ahora difícilmente evidenciables o que no tenían visibilidad arqueológica directa. Se presentan en este capítulo las principales líneas de investigación y problemáticas históricas en las que este tipo de analíticas intervienen, discutiendo sus posibilidades y limitaciones. Se remarca en este sentido el carácter interdisciplinario de los estudios bioquímicos y paleomoleculares y las posibilidades de abordar, a partir de los mismos, cuestiones de índole muy diversa.During the last years ancient DNA and stable isotope analyses has been currently used in archaeological research. These applications totally enlarged limits and possibilities of the zooarchaeological studies changing the historical meaning of the faunal assemblages recovered in archaeological sites. Ancient biomolecular analyses have different advantages from techniques and methods traditionally used in Zooarchaeology. First, the possibility to directly investigate the dynamics and way of life of the living animal populations (i.e. reproductive patterns, dietary habits and movility patterns), very difficult to achieve from traditional approaches. Secondly, broadening the temporal resolution of the samples, getting access to historical events in reduced timescales. These advantages allowed to fall on questions very difficult to evidence from archaeological studies, so far almost invisible. In this work are presented the main research lines and themes investigated from these analyses, debating current possibilities and limitations. This work highlight the interdisciplinary character of the ancient biomolecular studies and the possibilities to abroad different subjects

THz-conductivity of CVD graphene on different substrates

Optoelectronic properties of CVD graphene are charac-terized over a wide frequency range: THz, IR, visible and near-UV. We used Raman spectroscopy to characterize the synthesized graphene films. All graphene layers were deposited on various substrates, some ones transparent or flexible, such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), quartz and silicon. Transmission Terahertz time-domain spectroscopy (THz-TDS) method, in the range from 100 GHz to 3 THz, is used to analyze the transmittance, sheet conductivity and attenuation of graphene and the complex refractive index of substrates. From IR, near-UV and visible spectroscopy we obtained the transmittance of the substrate and the sample at those frequency ranges, and we deduced the graphene transmittance on each substrate. We found that it is close to 97% in most cases.Peer Reviewe