Probing and manipulating graphene physics at the atomic level

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física de la Materia Condensada. Fecha de lectura: 26-01-201

Atomic-scale visualization of multiferroicity in monolayer NiI2_2

Progress in layered van der Waals materials has resulted in the discovery of ferromagnetic and ferroelectric materials down to the monolayer limit. Recently, evidence of the first purely two-dimensional multiferroic material was reported in monolayer NiI$_2$. However, probing multiferroicity with scattering-based and optical bulk techniques is challenging on 2D materials, and experiments on the atomic scale are needed to fully characterize the multiferroic order at the monolayer limit. Here, we use scanning tunneling microscopy (STM) supported by theoretical calculations based on density functional theory (DFT) to probe and characterize the multiferroic order in monolayer NiI$_2$. We demonstrate that the type-II multiferroic order displayed by NiI$_2$, arising from the combination of a magnetic spin spiral order and a strong spin-orbit coupling, allows probing the multiferroic order in the STM experiments. Moreover, we directly probe the magnetoelectric coupling of NiI$_2$ by external electric field manipulation of the multiferroic domains. Our findings establish a novel point of view to analyse magnetoelectric effects at the microscopic level, paving the way towards engineering new multiferroic orders in van der Waals materials and their heterostructures

Quantum Confinement of Dirac Quasiparticles in Graphene Patterned with Sub-Nanometer Precision

Quantum confinement of graphene Dirac-like electrons in artificially crafted nanometer structures is a long sought goal that would provide a strategy to selectively tune the electronic properties of graphene, including bandgap opening or quantization of energy levels. However, creating confining structures with nanometer precision in shape, size, and location remains an experimental challenge, both for top-down and bottom-up approaches. Moreover, Klein tunneling, offering an escape route to graphene electrons, limits the efficiency of electrostatic confinement. Here, a scanning tunneling microscope (STM) is used to create graphene nanopatterns, with sub-nanometer precision, by the collective manipulation of a large number of H atoms. Individual graphene nanostructures are built at selected locations, with predetermined orientations and shapes, and with dimensions going all the way from 2 nm up to 1 µm. The method permits the patterns to be erased and rebuilt at will, and it can be implemented on different graphene substrates. STM experiments demonstrate that such graphene nanostructures confine very efficiently graphene Dirac quasiparticles, both in 0D and 1D structures. In graphene quantum dots, perfectly defined energy bandgaps up to 0.8 eV are found that scale as the inverse of the dot’s linear dimension, as expected for massless Dirac fermio

Quantum Confinement of Dirac Quasiparticles in Graphene Patterned with Sub‐Nanometer Precision

Quantum confinement of graphene Dirac‐like electrons in artificially crafted nanometer structures is a long sought goal that would provide a strategy to selectively tune the electronic properties of graphene, including bandgap opening or quantization of energy levels. However, creating confining structures with nanometer precision in shape, size, and location remains an experimental challenge, both for top‐down and bottom‐up approaches. Moreover, Klein tunneling, offering an escape route to graphene electrons, limits the efficiency of electrostatic confinement. Here, a scanning tunneling microscope (STM) is used to create graphene nanopatterns, with sub‐nanometer precision, by the collective manipulation of a large number of H atoms. Individual graphene nanostructures are built at selected locations, with predetermined orientations and shapes, and with dimensions going all the way from 2 nm up to 1 µm. The method permits the patterns to be erased and rebuilt at will, and it can be implemented on different graphene substrates. STM experiments demonstrate that such graphene nanostructures confine very efficiently graphene Dirac quasiparticles, both in 0D and 1D structures. In graphene quantum dots, perfectly defined energy bandgaps up to 0.8 eV are found that scale as the inverse of the dot’s linear dimension, as expected for massless Dirac fermions.This work was supported by AEI and FEDER under projects MAT2016-80907-P and MAT2016-77852-C2-2-R (AEI/FEDER, UE) by the Fundación Ramón Areces, the Comunidad de Madrid NMAT2D-CM program under grant S2018/NMT-4511, and the Spanish Ministry of Science and Innovation, through the “María de Maeztu” Programme for Units of Excellence in R&D (CEX2018-000805-M). European Union through the FLAG-ERA program HiMagGraphene project PCIN-2015-030; No. ANR-15-GRFL-0004) and the Graphene Flagship program (Grant agreement 604391). J.L.L acknowledges financial support from the ETH Fellowship program; J.F.-R. acknowledges supported by Fundação para a Ciência e a Tecnologia grants P2020-PTDC/FIS-NAN/3668/2014 and TAPEXPL/NTec/0046/2017

Intrusion Detection With Unsupervised Techniques for Network Management Protocols Over Smart Grids

[Abstract] The present research work focuses on overcoming cybersecurity problems in the Smart Grid. Smart Grids must have feasible data capture and communications infrastructure to be able to manage the huge amounts of data coming from sensors. To ensure the proper operation of next-generation electricity grids, the captured data must be reliable and protected against vulnerabilities and possible attacks. The contribution of this paper to the state of the art lies in the identification of cyberattacks that produce anomalous behaviour in network management protocols. A novel neural projectionist technique (Beta Hebbian Learning, BHL) has been employed to get a general visual representation of the traffic of a network, making it possible to identify any abnormal behaviours and patterns, indicative of a cyberattack. This novel approach has been validated on 3 different datasets, demonstrating the ability of BHL to detect different types of attacks, more effectively than other state-of-the-art methods

Decreased salivary lactoferrin levels are specific to Alzheimer's disease

Background: Evidences of infectious pathogens in Alzheimer's disease (AD) brains may suggest a deteriorated innate immune system in AD pathophysiology. We previously demonstrated reduced salivary lactoferrin (Lf) levels, one of the major antimicrobial proteins, in AD patients. Methods: To assess the clinical utility of salivary Lf for AD diagnosis, we examine the relationship between salivary Lf and cerebral amyloid-beta (A beta) load using amyloid-Positron-Emission Tomography (PET) neuroimaging, in two different cross-sectional cohorts including patients with different neurodegenerative disorders. Findings: The diagnostic performance of salivary Lf in the cohort 1 had an area under the curve [AUC] of 0.95 (0.911-0.992) for the differentiation of the prodromal AD/AD group positive for amyloid-PET (PET+) versus healthy group, and 0.97 (0.924-1) versus the frontotemporal dementia (FTD) group. In the cohort 2, salivary Lf had also an excellent diagnostic performance in the health control group versus prodromal AD comparison: AUC 0.93 (0.876-0.989). Salivary Lf detected prodromal AD and AD dementia distinguishing them from FTD with over 87% sensitivity and 91% specificity. Interpretation: Salivary Lf seems to have a very good diagnostic performance to detect AD. Our findings support the possible utility of salivary Lf as a new non-invasive and cost-effective AD biomarker.This study was supported by Dr. Carro grants from Instituto de Salud Carlos III (FIS15/00780, FIS18/00118), FEDER, Comunidad de Madrid (S2017/BMD-3700; NEUROMETAB-CM), and CIBERNED (PI2016/01). This study was also supported by research grants from the Spanish Ministry of Economy and Competitiveness (SAF201785310-R to Dr. Cantero, PSI2017-85311-P to Dr. Atienza); International Centre on ageing CENIE-POCTEP (0348_CIE_6_E to Dr. Atienza); and CIBERNED (CB06/05/1111 to Dr. Cantero). Dr. Bueno receives research funding from the Instituto de Salud Carlos III, Spain (PIE16/00021, PI17/01799). The H2H-Spain Study was supported in Spain by grant PIE16/00021 from Instituto Carlos III, Ministry of Science, Innovation and Universities, and additional funds from the Centro Nacional de Investigaciones Cardiovasculares (CNIC). The CNIC is supported by the Ministry of Economy, Industry and Competitiveness and the Pro CNIC Foundation, and is a Severo Ochoa Centre of Excellence (SEV-2015-0505). The funders had no role in the conceptualisation, study design, data collection analysis and preparation of this manuscript

The anti-aging factor Klotho protects against acquired long QT syndrome induced by uremia and promoted by fibroblast growth factor 23

[Background]: Chronic kidney disease (CKD) is associated with increased propensity for arrhythmias. In this context, ventricular repolarization alterations have been shown to predispose to fatal arrhythmias and sudden cardiac death. Between mineral bone disturbances in CKD patients, increased fibroblast growth factor (FGF) 23 and decreased Klotho are emerging as important effectors of cardiovascular disease. However, the relationship between imbalanced FGF23-Klotho axis and the development of cardiac arrhythmias in CKD remains unknown. [Methods]: We carried out a translational approach to study the relationship between the FGF23–Klotho signaling axis and acquired long QT syndrome in CKD-associated uremia. FGF23 levels and cardiac repolarization dynamics were analyzed in patients with dialysis-dependent CKD and in uremic mouse models of 5/6 nephrectomy (Nfx) and Klotho deficiency (hypomorphism), which show very high systemic FGF23 levels. [Results]: Patients in the top quartile of FGF23 levels had a higher occurrence of very long QT intervals (> 490 ms) than peers in the lowest quartile. Experimentally, FGF23 induced QT prolongation in healthy mice. Similarly, alterations in cardiac repolarization and QT prolongation were observed in Nfx mice and in Klotho hypomorphic mice. QT prolongation in Nfx mice was explained by a significant decrease in the fast transient outward potassium (K+) current (Itof), caused by the downregulation of K+ channel 4.2 subunit (Kv4.2) expression. Kv4.2 expression was also significantly reduced in ventricular cardiomyocytes exposed to FGF23. Enhancing Klotho availability prevented both long QT prolongation and reduced Itof current. Likewise, administration of recombinant Klotho blocked the downregulation of Kv4.2 expression in Nfx mice and in FGF23-exposed cardiomyocytes. [Conclusion]: The FGF23–Klotho axis emerges as a new therapeutic target to prevent acquired long QT syndrome in uremia by minimizing the predisposition to potentially fatal ventricular arrhythmias and sudden cardiac death in patients with CKD.This work was supported by projects from the Instituto de Salud Carlos III, Ministry of Economy, Industry and Competitiveness (PI17/01093, PI17/01193, PI20/00763, CP15/00129, F18/00261, CPII20/00022, SAF2017-84777-R, PID2020-113238RB-I00), from the Sociedad Española de Cardiología (SEC), and from the Fundación Renal Íñigo Alvarez de Toledo (FRIAT), co-funded by the European Regional Development Fund (Fondos FEDER)

Role of previous systemic antibiotic therapy on the probability of recurrence after an initial episode of Clostridioides difficile infection treated with vancomycin

© The Author(s) 2023. Published by Oxford University Press on behalf of British Society for Antimicrobial Chemotherapy. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.[Objectives ] To investigate the role of previous antibiotic therapy in the risk of recurrence after a Clostridioides difficile infection (CDI) treated with vancomycin.[Methods] Multicentre observational study. Patients with a CDI episode achieving clinical cure with oral vancomycin and followed up 8 weeks were included. Previous antibiotic exposure up to 90 days was collected. Multivariate analysis of predictors of recurrence adjusted by the propensity score (PS) of being previously treated with each non-CDI antibiotic was performed.[Results] Two hundred and forty-one patients were included; 216 (90%) had received systemic antibiotics. Fifty-three patients (22%) had a CDI recurrence. Rates of recurrence were lower in those treated with piperacillin/tazobactam in the last month when compared with those not receiving piperacillin/tazobactam [3 (7%) versus 50 (25%); P = 0.01], whereas higher rates were seen in those treated with cephalosporins in the last month [26/87 (30%) versus 27/154 (17%); P = 0.03]. In multivariate analysis controlled by the inverse probability of treatment weighting by PS, receiving ≥5 days of piperacillin/tazobactam in the last month as the last antibiotic regimen prior to CDI was independently associated with a lower risk of recurrence [adjusted OR (AOR) 0.13; 95% CI: 0.06–0.29; P < 0.0001] whereas exposure for ≥5 days to cephalosporins (versus piperacillin/tazobactam) was associated with an increased risk (AOR 10.9; 95% CI: 4.4–27.1; P < 0.0001).[Conclusions] Recent use of piperacillin/tazobactam might be associated with a lower risk of CDI recurrence, while recent use of cephalosporins might promote an increased risk. These findings should be considered when treating hospitalized patients.This work has been partially financed by the Instituto de Salud Carlos III (project PI20/P1450) and co-financed by the European Union (ERDF) ‘A way of making Europe’. In addition, it has also been partially funded by Merck, Sharp and Dohme (Ref. IISP 60379 and 60386).Peer reviewe

Jardins per a la salut

Facultat de Farmàcia, Universitat de Barcelona. Ensenyament: Grau de Farmàcia. Assignatura: Botànica farmacèutica. Curs: 2014-2015. Coordinadors: Joan Simon, Cèsar Blanché i Maria Bosch.Els materials que aquí es presenten són el recull de les fitxes botàniques de 128 espècies presents en el Jardí Ferran Soldevila de l’Edifici Històric de la UB. Els treballs han estat realitzats manera individual per part dels estudiants dels grups M-3 i T-1 de l’assignatura Botànica Farmacèutica durant els mesos de febrer a maig del curs 2014-15 com a resultat final del Projecte d’Innovació Docent «Jardins per a la salut: aprenentatge servei a Botànica farmacèutica» (codi 2014PID-UB/054). Tots els treballs s’han dut a terme a través de la plataforma de GoogleDocs i han estat tutoritzats pels professors de l’assignatura. L’objectiu principal de l’activitat ha estat fomentar l’aprenentatge autònom i col·laboratiu en Botànica farmacèutica. També s’ha pretès motivar els estudiants a través del retorn de part del seu esforç a la societat a través d’una experiència d’Aprenentatge-Servei, deixant disponible finalment el treball dels estudiants per a poder ser consultable a través d’una Web pública amb la possibilitat de poder-ho fer in-situ en el propi jardí mitjançant codis QR amb un smartphone

Socio-Demographic Health Determinants Are Associated with Poor Prognosis in Spanish Patients Hospitalized with COVID-19

Introduction Social vulnerability is a known determinant of health in respiratory diseases. Our aim was to identify whether there are socio-demographic factors among COVID-19 patients hospitalized in Spain and their potential impact on health outcomes during the hospitalization. Methods A multicentric retrospective case series study based on administrative databases that included all COVID-19 cases admitted in 19 Spanish hospitals from 1 March to 15 April 2020. Socio-demographic data were collected. Outcomes were critical care admission and in-hospital mortality. Results We included 10,110 COVID-19 patients admitted to 18 Spanish hospitals (median age 68 (IQR 54–80) years old; 44.5% female; 14.8% were not born in Spain). Among these, 779 (7.7%) cases were admitted to critical care units and 1678 (16.6%) patients died during the hospitalization. Age, male gender, being immigrant, and low hospital saturation were independently associated with being admitted to an intensive care unit. Age, male gender, being immigrant, percentile of average per capita income, and hospital experience were independently associated with in-hospital mortality. Conclusions Social determinants such as residence in low-income areas and being born in Latin American countries were associated with increased odds of being admitted to an intensive care unit and of in-hospital mortality. There was considerable variation in outcomes between different Spanish centers.JPA is under contract within the Ramón y Cajal Program (RYC-2016-20155, Ministerio de Economía, Industria y Competitividad, Spain). Investigators of Spanish Social-Environmental COVID-19 Register: Steering Committee: F. Javier Martín-Sánchez, Adrián Valls Carbó, Carmen Martínez Valero, Juan de D. Miranda, Juan Pedro Arrebola, Marta Esteban López, Annika Parviainen, Òscar Miró, Pere Llorens, Sònia Jiménez, Pascual Piñera, Guillermo Burillo, Alfonso Martín, Jorge García Lamberechts, Javier Jacob, Aitor Alquézar, Juan González del Castillo, Amanda López Picado and Iván Núñez. Participating centers: Oscar Miró y Sonia Jimenez. Hospital Clinic de Barcelona. José María Ferreras Amez. Hospital Clínico Universitario Lozano Blesa. Rafael Rubio Díaz. Complejo Hospitalario de Toledo. Julio Javier Gamazo del Rio. Hospital Universitario de Galdakao. Héctor Alonso. Hospital Universitario Miguel de Valdecilla. Pablo Herrero. Hospital Universitario Central de Asturias. Noemí Ruiz de Lobera. Hospital San Pedro de Logroño. Carlos Ibero. Complejo Hospitalario de Navarra. Plácido Mayan. Hospital Clínico Universitario de Santiago. Rosario Peinado. Complejo Hospitalario Universitario de Badajoz. Carmen Navarro Bustos. Hospital Universitario Virgen de la Macarena. Jesús Álvarez Manzanares. Hospital Universitario Rio Hortega. Francisco Román. Hospital Universitario General de Alicante. Pascual Piñera. Hospital Universitario Reina Sofia de Murcia. Guillermo Burillo. Hospital Universitario de Canarias de Tenerife. Javier Jacob. Hospital Universitario de Bellvitge. Carlos Bibiano. Hospital Universitario Infanta Leonor.Peer reviewe