Flow injection determination of readily assimilable nitrogen compounds during vinification

A flow injection method for the determination of readily assimilable nitrogen (r.a.n.), i.e. ammonium and aminated nitrogen, is reported. The difference in pH of the sample in the presence and absence of formaldehyde, which blocks the amino function, provides the value of r.a.n. by monitoring the changes in absorbance of bromothymol blue at 616 nm. The detection and quantification limits are 10 and 11.6 mg l-1, respectively; the reproducibility and repeatability are 3.94 mg l-1 and 1.35 mg l-1, respectively; and the sample throughput is 20 samples h-1. The method has been applied to the analysis of 120 samples of must and wine subjected to biological aging. The proposed method also provides good correlation with the reference method used in routine analysis, and it is faster and gives sufficient precision for wineries requirements

Raman microprobe characterization of electrodeposited S-rich CuIn(S,Se)2 for photovoltaic applications: Microstructural analysis

This article reports a detailed Raman scattering and microstructural characterization of S-rich CuIn(S,Se)2 absorbers produced by electrodeposition of nanocrystalline CuInSe2 precursors and subsequent reactive annealing under sulfurizing conditions. Surface and in-depth resolved Raman microprobe measurements have been correlated with the analysis of the layers by optical and scanning electron microscopy, x-ray diffraction, and in-depth Auger electron spectroscopy. This has allowed corroboration of the high crystalline quality of the sulfurized layers. The sulfurizing conditions used also lead to the formation of a relatively thick MoS2 intermediate layer between the absorber and the Mo back contact. The analysis of the absorbers has also allowed identification of the presence of In-rich secondary phases, which are likely related to the coexistence in the electrodeposited precursors of ordered vacancy compound domains with the main chalcopyrite phase, in spite of the Cu-rich conditions used in the growth. This points out the higher complexity of the electrodeposition and sulfurization processes in relation to those based in vacuum deposition techniques

Numerical Simulation of the Stiffness Evolution With Curing of Pavement Sections Rehabilitated Using Cold In-Place Recycling Technology

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] Cold in-place recycling (CIR) technologies are becoming one of the main bets in the road sector to promote the reduction of greenhouse gas emissions. This technique also contributes to the circular economy, reusing 100% of the RAP from worn roads. In this research, numerical simulations of CIR sections are presented. The nonlinear behaviour of the CIR-base material is modelled using three predictive models based on triaxial test results. Variations in the performance depending on the type of subbase, the curing of the CIR-base material and its thickness, and the effect of the wearing-course were analysed. The response of the sections with unbound granular subbase proved to be very sensitive to variations in the parameters studied, and the increase in CIR base thickness was beneficial, while the opposite occurred with a cement-treated subbase.The authors would like to acknowledge funding for the project BIA2016-80317-R from the Spanish Ministry of Economy and Competitiveness (MINECO), with an associated pre-doctoral scholarship for the training of research workers (FPI) BES-2017-079633. An special acknowledgement to the Universidade da Coruña/ CISUG for funding Elsevier’s open access charg

Point defects on graphene on metals

Understanding the coupling of graphene with its local environment is critical to be able to integrate it in tomorrow's electronic devices. Here we show how the presence of a metallic substrate affects the properties of an atomically tailored graphene layer. We have deliberately introduced single carbon vacancies on a graphene monolayer grown on a Pt(111) surface and investigated its impact in the electronic, structural and magnetic properties of the graphene layer. Our low temperature scanning tunneling microscopy studies, complemented by density functional theory, show the existence of a broad electronic resonance above the Fermi energy associated with the vacancies. Vacancy sites become reactive leading to an increase of the coupling between the graphene layer and the metal substrate at these points; this gives rise to a rapid decay of the localized state and the quenching of the magnetic moment associated with carbon vacancies in free-standing graphene layers

Predictive control of a three-phase UPS inverter using two steps prediction horizon

A Model Predictive Control scheme is used for voltage control in a three-phase inverter with output LC filter. The controller uses a model of the system to calculate predictions of the future value of the system variables for a given voltage vector sequence. A cost function considering the voltage errors is defined and the voltage vectors that minimize it are selected and applied in the converter. The effect of considering different number of prediction steps is studied in this work in terms of THD. Simulation results for one and two prediction steps are presented and compared

Detection of a multi-shell planetary nebula around the hot subdwarf O-type star 2MASS J19310888+4324577

(Abridged) The origin of hot subdwarf O-type stars (sdOs) remains unclear since their discovery in 1947. Among others, a post-Asymptotic Giant Branch (post-AGB) origin is possible for a fraction of sdOs. We are involved in a comprehensive ongoing study to search for and to analyze planetary nebulae (PNe) around sdOs with the aim of establishing the fraction and properties of sdOs with a post-AGB origin. We use deep Halpha and [OIII] images of sdOs to detect nebular emission and intermediate resolution, long-slit optical spectroscopy of the detected nebulae and their sdO central stars. These data are complemented with other observations for further analysis of the detected nebulae. We report the detection of an extremely faint, complex PN around 2MASS J19310888+4324577 (2M1931+4324), a star classified as sdO in a binary system. The PN shows a bipolar and an elliptical shell, whose major axes are oriented perpendicular to each other, and high-excitation structures outside the two shells. WISE archive images show faint, extended emission at 12 and 22 microns in the inner nebular regions. The internal nebular kinematics is consistent with a bipolar and a cylindrical/ellipsoidal shell, in both cases with the main axis mainly perpendicular to the line of sight. The nebular spectrum only exhibits Halpha, Hbeta and [OIII]4959,5007 emission lines, but suggests a very low-excitation ([OIII]/Hbeta = 1.5), in strong contrast with the absence of low-excitation emission lines. The spectrum of 2M1931+4324 presents narrow, ionized helium absorptions that confirm the previous sdO classification and suggest an effective temperature >= 60000 K. The binary nature of 2M1931+4324, its association with a complex PN, and several properties of the system provide strong support for the idea that binary central stars are a crucial ingredient in the formation of complex PNe.Comment: 8 pages, 7 figures, accepted in Astronomy and Astrophysic

Defense and Attack Techniques against File-based TOCTOU Vulnerabilities: a Systematic Review

File-based Time-of-Check to Time-of-Use (TOCTOU) race conditions are a well-known type of security vulnerability. A wide variety of techniques have been proposed to detect, mitigate, avoid, and exploit these vulnerabilities over the past 35 years. However, despite these research efforts, TOCTOU vulnerabilities remain unsolved due to their non-deterministic nature and the particularities of the different filesystems involved in running vulnerable programs, especially in Unix-like operating system environments. In this paper, we present a systematic literature review on defense and attack techniques related to the file-based TOCTOU vulnerability. We apply a reproducible methodology to search, filter, and analyze the most relevant research proposals to define a global and understandable vision of existing solutions. The results of this analysis are finally used to discuss future research directions that can be explored to move towards a universal solution to this type of vulnerability. Autho

Insectos acuáticos asociados a arroyos intermitentes de la serranía de la Macuira, Guajira- Colombia

Los insectos acuáticos tienen gran importancia en los ecosistemas acuáticos fluviales debido a su alta abundancia y diversidad. En este trabajo se estudiaron los ensamblajes de insectos acuáticos en La Macuira, norte de La Guajira colombiana. En esta zona se seleccionaron cinco arroyos intermitentes como sitios de muestreo, conocidos como Mekijanoü,Chaamaalüü, Kanewerü, Mmalaüü y Kajashiwoü. En el mes de junio del 2015 se muestreó con red Surber durante cinco minutos, mediante la remoción del sustrato en contra corriente;además, se tomaron muestras de hojarasca manualmente (aprox 500g). Todas las muestras recolectadas en cada sitio se integraron para conformar una muestra compuesta. Los organismos se guardaron en bolsas plásticas y se preservaron con etanol al 90%. En laboratorio, las muestras se limpiaron y se identificaron hasta el nivel más detallado posible.Se colectaron en total 545 individuos agrupados en 25 géneros de insectos acuáticos distribuidos en 19 familias y 7 órdenes. El arroyo Mekijanoü presentó la mayor abundancia (411 individuos) y riqueza de géneros en el que predominó la presencia del género Heterelmis (Coleoptera, Elmidae). Por otra parte, el arroyo que presento la menor abundancia de insectos acuáticos fue Kajashiwoü (20 individuos) lo cual podría ser consecuencia de la formación de pozos y la poca conectividad entre estos. Se aplico el índice BMWP/Col para determinar la calidad del agua de cada uno de los arroyos. Los valores del índice oscilaron entre 41 y 87, lo cual indica que cuatro de los cinco arroyos presentaron una posible moderada contaminación y solo uno se encontraba ligeramente contaminado. Se registran por primera vez para la Serranía de la Macuira los géneros Heterelmis (Coleoptera: Elmidae), Corydalus (Megaloptera: Corydalidae), Rhagovelia (Hemiptera: Vellidae), Mayobaetis (Baetidae: Ephemeroptera), Tholymis (Libellulidae: Odonata) y Mecistogaster (Coenagrionidae Odonata)

KMOS LENsing Survey (KLENS) : morpho-kinematic analysis of star-forming galaxies at z∼2z \sim 2

We present results from the KMOS lensing survey-KLENS which is exploiting gravitational lensing to study the kinematics of 24 star forming galaxies at $1.4<z<3.5$ with a median mass of $\rm log(M_\star/M_\odot)=9.6$ and median star formation rate (SFR) of $\rm 7.5\,M_\odot\,yr^{-1}$. We find that 25% of these low-mass/low-SFR galaxies are rotation dominated, while the majority of our sample shows no velocity gradient. When combining our data with other surveys, we find that the fraction of rotation dominated galaxies increases with the stellar mass, and decreases for galaxies with a positive offset from the main sequence. We also investigate the evolution of the intrinsic velocity dispersion, $\sigma_0$, as a function of the redshift, $z$, and stellar mass, $\rm M_\star$, assuming galaxies in quasi-equilibrium (Toomre Q parameter equal to 1). From the $z-\sigma_0$ relation, we find that the redshift evolution of the velocity dispersion is mostly expected for massive galaxies ($\rm log(M_\star/M_\odot)>10$). We derive a $\rm M_\star-\sigma_0$ relation, using the Tully-Fisher relation, which highlights that a different evolution of the velocity dispersion is expected depending on the stellar mass, with lower velocity dispersions for lower masses, and an increase for higher masses, stronger at higher redshift. The observed velocity dispersions from this work and from comparison samples spanning $0<z<3.5$ appear to follow this relation, except at higher redshift ($z>2$), where we observe higher velocity dispersions for low masses ($\rm log(M_\star/M_\odot)\sim 9.6$) and lower velocity dispersions for high masses ($\rm log(M_\star/M_\odot)\sim 10.9$) than expected. This discrepancy could, for instance, suggest that galaxies at high-$z$ do not satisfy the stability criterion, or that the adopted parametrisation of the specific star formation rate and molecular properties fail at high redshift.Comment: Accepted for publication in A&A, 21 pages, 10 figure

Vector magnetic hysteresis of hard superconductors

Critical state problems which incorporate more than one component for the magnetization vector of hard superconductors are investigated. The theory is based on the minimization of a cost functional ${\cal C}[\vec{H}(\vec{x})]$ which weighs the changes of the magnetic field vector within the sample. We show that Bean's simplest prescription of choosing the correct sign for the critical current density $J_c$ in one dimensional problems is just a particular case of finding the components of the vector $\vec{J}_c$. $\vec{J}_c$ is determined by minimizing ${\cal C}$ under the constraint $\vec{J}\in\Delta (\vec{H},\vec{x})$, with $\Delta$ a bounded set. Upon the selection of different sets $\Delta$ we discuss existing crossed field measurements and predict new observable features. It is shown that a complex behavior in the magnetization curves may be controlled by a single external parameter, i.e.: the maximum value of the applied magnetic field $H_m$.Comment: 10 pages, 9 figures, accepted in Phys. Rev.