Superconducting parity effect across the Anderson limit

How small superconductors can be? For isolated nanoparticles subject to quantum size effects, P.W. Anderson conjectured in 1959 that superconductivity could only exist when the electronic level spacing $\delta$ is smaller than the superconducting gap energy $\Delta$. Here, we report a scanning tunneling spectroscopy study of superconducting lead (Pb) nanocrystals grown on the (110) surface of InAs. We find that for nanocrystals of lateral size smaller than the Fermi wavelength of the 2D electron gas at the surface of InAs, the electronic transmission of the interface is weak; this leads to Coulomb blockade and enables the extraction of the electron addition energy of the nanocrystals. For large nanocrystals, the addition energy displays superconducting parity effect, a direct consequence of Cooper pairing. Studying this parity effect as function of nanocrystal volume, we find the suppression of Cooper pairing when the mean electronic level spacing overcomes the superconducting gap energy, thus demonstrating unambiguously the validity of the Anderson criterion.Comment: 25 pages, 5 figures in main articles, 9 in supplementar

Evidence for a Cr metastable phase as a tracer in DLI-MOCVD chromium hard coatings usable in high temperature environment

Cr deposits are widely used as protective coatings but multifunctional performances are required in harsh environments motivating research on new processes. MOCVD of Cr metal coatings was carried out by direct liquid injection (DLI) of a unique solution containing bis(ethylbenzene)chromium as metal source and thiophenol as inhibitor of carbide formation. A low amount (<6%) of the metastable δ-Cr phase was found embedded in the stable α-Cr phase. The formation of this metastable phase originates from both the low deposition temperature (<723 K) and the use of thiophenol. It was not reported under other CVD conditions. Dense coatings were deposited by implementing a multilayer growth mode. Such coatings exhibit a high nanohardness of about 17 GPa. The δ-Cr metastable phase undergoes an irreversible structural transformation to bcc-Cr above 723 K. The mechanical properties of coatings are not affected by the structural transformation because of the similarity of their crystallographic structures (both cubic), their density very close (a volume contraction of only 0.4% during the transformation) and its low content. This metastable phase is a signature of the DLI-MOCVD process and it can be used as a tracer for Cr coatings operating in high temperature environment without loss of the basic properties

Quantum confinement effects in Pb Nanocrystals grown on InAs

In the recent work of Ref.\cite{Vlaic2017-bs}, it has been shown that Pb nanocrystals grown on the electron accumulation layer at the (110) surface of InAs are in the regime of Coulomb blockade. This enabled the first scanning tunneling spectroscopy study of the superconducting parity effect across the Anderson limit. The nature of the tunnel barrier between the nanocrystals and the substrate has been attributed to a quantum constriction of the electronic wave-function at the interface due to the large Fermi wavelength of the electron accumulation layer in InAs. In this manuscript, we detail and review the arguments leading to this conclusion. Furthermore, we show that, thanks to this highly clean tunnel barrier, this system is remarkably suited for the study of discrete electronic levels induced by quantum confinement effects in the Pb nanocrystals. We identified three distinct regimes of quantum confinement. For the largest nanocrystals, quantum confinement effects appear through the formation of quantum well states regularly organized in energy and in space. For the smallest nanocrystals, only atomic-like electronic levels separated by a large energy scale are observed. Finally, in the intermediate size regime, discrete electronic levels associated to electronic wave-functions with a random spatial structure are observed, as expected from Random Matrix Theory.Comment: Main 12 pages, Supp: 6 page

Chromium carbide growth at low temperature by a highly efficient DLI-MOCVD process in effluent recycling mode

The effect of direct recycling of effluents on the quality of CrxCy coatings grown by MOCVD using direct liquid injection (DLI) of bis(ethylbenzene)chromium(0) in toluene was investigated. The results are compared with those obtained using non-recycled solutions of precursor. Both types of coatings exhibit the same features. They are amorphous in the temperature range 673–823 K. They exhibit a dense and glassy-like microstructure and a high hardness (> 23 GPa). Analyses at the nanoscale revealed a nanocomposite microstructure consisting of free-C domains embedded in an amorphous Cr7C3 matrix characterized by strong interfaces and leading to an overall composition slightly higher than Cr7C3. The stiffness and strength of these interfaces are mainly due to at least two types of chemical bonds between Cr atoms and free-C: (i) Cr intercalation between graphene sheets and(ii) hexahapto η6-Cr bonding on the external graphene sheets of the free-C domains. The density of these interactions was found increasing by decreasing the concentration of the injected solution, as this occurred using a recycled solution. As a result, “recycled” coatings exhibit a higher nanohardness (29 GPa) than “new” coatings (23 GPa). This work demonstrates that using bis(arene)M(0) precursors, direct recycling of effluents is an efficient route to improve the conversion yield of DLI-MOCVD process making it cost-effective and competitive to produce protective carbide coatings of transition metals which share the same metal zero chemistry

Analysis and design of a model of OT control and supervision architectures in the field of industrial cybersecurity

Moltes empreses han decidit aprofitar els avenços realitzats en l'àmbit dels entorns informàtics per millorar i optimitzar les seves capacitats de producció i/o serveis oferts. Tot i que es tracta d'un gran avenç tecnològic (alguns utilitzen el terme "Indústria 4.0" per referir-se a aquesta tecnologia per identificar-la amb l'anomenada quarta revolució industrial), també obre un nou paradigma per al concepte de seguretat industrial. El fet que cada cop hi hagi més dispositius que no s'havien dissenyat per protegir-se contra ciberatacs estan connectats a Internet fa que apareguin un gran nombre de vulnerabilitats abans no considerades. L'objectiu d'aquest treball és mostrar el procés de securització d'un hipotètic sistema de distribució d'aigua. Per fer-ho, partirem d'una arquitectura que es podria qualificar d'insegura. Seguint les directrius de les directrius CCN_STIC_480 i amb l'ajuda de les normes vigents com ISO 27000 i IEC62443, es realitzarà una anàlisi de riscos i es proposaran determinades mesures aplicables per mitigar el risc d'un ciberatac.Muchas compañías han decidido aprovechar los avances hechos en el ámbito de los entornos IT para poder mejorar y optimizar sus capacidades de producción y/o servicios ofrecidos. Si bien se trata de un gran avance en el ámbito tecnológico (algunos usan el termo “Indústria 4.0” para referirse a esta tecnología con tal de identificarla con la supuesta cuarta revolución industrial), también abre un nuevo paradigma del concepto de seguridad industrial. El hecho que cada vez más dispositivos que no habían estado diseñados para protegerse de ciberataques estén conectados a Internet supone la aparición de una gran cantidad de vulnerabilidades no contempladas anteriormente. El objetivo de este trabajo es mostrar el proceso de securización de un sistema de distribución de agua hipotético. Para ello se partirá de una arquitectura que se podría clasificar como insegura. Siguiendo las directrices de las guías CCN_STIC_480 y con la ayuda de normativas actuales como la ISO 27000 i IEC62443 se realizará un análisis de riesgos y se propondrán ciertas medidas aplicables para mitigar el riesgo a un ciberataque.Many companies have decided to take advantage of the advances made in the field of IT environments in order to improve and optimise their production capacities and/or services offered. While this is a technological breakthrough (some use the term "Industry 4.0" to refer to this technology in order to identify it with the so-called fourth industrial revolution), it also opens up a new paradigm for the concept of industrial security. The fact that more and more devices that had not been designed to protect against cyber-attacks are connected to the Internet means that a large number of previously unconsidered vulnerabilities are appearing. The aim of this paper is to show the process of securitisation of a hypothetical water distribution system. To do so, we will start from an architecture that could be classified as insecure. Following the guidelines of the CCN_STIC_480 guidelines and with the help of current standards such as ISO 27000 and IEC62443, a risk analysis will be carried out and certain applicable measures will be proposed to mitigate the risk of a cyber-attack.Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructur

Species complex and temporal associations between coccinellids and aphids in alfalfa stands in Spain

: Alfalfa is known to be an important reservoir harboring natural enemies. The reduction in insecticide sprayings in recent years has allowed us to study the coccinellid species complex in this crop and the relationship between these predators and aphids. Alfalfa was sampled by sweep-netting throughout its productive period in several commercial stands each year between 2010 and 2021. The numbers and species of aphids and coccinellids were recorded. Sixteen coccinellid species were found. Coccinella septempunctata and Hippodamia variegata were, by far, the most prevalent species, with the former dominating during the first and second intercuts, whereas the latter dominated from the third to the fifth intercut. Acyrthosiphon pisum and Therioaphis trifolii were the most abundant aphid species, peaking in the second and fourth intercuts, respectively. Positive correlations were found between the abundance of C. septempunctata and A. pisum at the second intercut, between H. variegata and T. trifolii at the fourth intercut, and between H. variegata and the total number of aphids in the fifth intercut. This study helps to increase the knowledge on the predator–prey relationships of this crop and allows for designing strategies of conservation biological control against aphids.: This study was funded by the Ministerio de Ciencia, Innovación y Universidades, Spanish Government (Project AGL2017-84127-R: Arable crop management and landscape interactions for pest control). RM holds the predoctoral fellowship FPI-PRE2018-083602 from the Ministerio de Ciencia, Innovación y Universidades and ALM holds a predoctoral JADE Plus fellowship from the University of Lleida (Spain)

Estudio de Link Network Analysis y su influencia en el Posicionamiento en Buscadores

[ES] Este Trabajo de Fin de Grado de la titulación de Grado en Ingeniería Informática consiste en el análisis de las redes de links, con la finalidad de que un enlace en un nicho de mercado, pueda mejorar su visibilidad en los buscadores. El proyecto también estudia una serie de herramientas analíticas para luego, exportar los datos en la herramienta de código libre Gephi. Gracias al uso de grafos, se podrán observar, de manera visual, algunas conclusiones sobre dicho estudio, concretamente, en el universo vinícola.[EN] This is the Final Project of the Engineering degree in Computer Science and it is about link network analysis, looking for a way in which a link in a prospective market could improve search engine visibility. The Project also studies some analytical tools from which the data was exported into an open source tool called Gephi. Through the use of graphs, some conclusions about the research, specifically in the world of wine, can be visualised.Capraru Pons, CA. (2015). Estudio de Link Network Analysis y su influencia en el Posicionamiento en Buscadores. http://hdl.handle.net/10251/54541.TFG

The aroma of toasted oak wood (<i>Quercus petraea</i>): from sensory analysis to molecular characterisation

The chemical complexity of the aroma compounds developed by oak wood during the toasting process is known to contribute to the quality of wines and spirits after barrel ageing. Molecular characterisation of toasted oak wood has increased steadily in recent years, using the traditional olfactory-guided approach by gas chromatography coupled with olfactometry and mass spectrometry (GC-O-MS); however, few studies have focused on its sensory characterisation. In this study, a sensory characterisation of oak wood (Quercus petraea) was first carried out during toasting in order to identify any descriptors that had not yet been characterised from a molecular point of view. Thus, in the second part of this work, we were able to identify volatile compounds associated with the aroma of toasted oak wood. Based on previous work in oenology, the sensory characterisation of oak wood was carried out in three stages: identification, structuring and description of a sensory space. Data processing of the 215 descriptors generated by the panel of experts revealed six descriptors specific to the aroma of oak wood throughout its toasting (i.e., fresh wood, fresh green, sweet, roasted, spicy and smoky). The results were represented graphically in the form of an aroma wheel, which was used to highlight the descriptors that had not yet been characterised from a molecular point of view. Thus, two volatile compounds were identified: thymoquinone (pencil and cedar odour) and verbenone (fresh, menthol and tealeaf odour). Their evolution in oak wood during toasting and their distribution in different wood species used in oenology (sessile oak, pedunculate oak, American oak, Caucasian oak, acacia and chestnut) were studied. Their sensory impact was studied by assessing their olfactory detection threshold in a model wine solution. The thresholds were evaluated at 49 ng/L for thymoquinone and 193 µg/L for verbenone

CONSTRUÇÕES UTILIZANDO ESTRUTURAS DE MADEIRA

A madeira é um material que está presente em grande parte das obras de construção civil. Com base neste contexto, o presente trabalho tem como objetivo apresentar um estudo sobre a utilização da madeira de forma estrutural em edificações. Para isso, este trabalho propôs uma coleta de dados através de um questionário submetido à profissionais das áreas de engenharia civil e arquitetura. O questionário visa investigar o nível de conhecimento que esses profissionais têm em relação ao material de estudo, e qual sua percepção do emprego da madeira como elemento estrutural. Os resultados do questionário indicam que a madeira é um importante item de construção, porém não como elemento estrutural como é caso de concreto armado. Os resultados indicaram que os profissionais utilizam madeira como um item temporário, de forma que, quando a sua utilização se faz necessário para um maior tempo, quase que de forma exclusiva esse material é empregado em coberturas e esquadrias, sendo para as demais solicitações empregado estrutura convencional de concreto armado e/ou aço