1,442 research outputs found

    Thickness dependent magnetic anisotropy of ultrathin LCMO epitaxial thin films

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    The magnetic properties of La0.7Ca0.3MnO3 (LCMO) manganite thin films were studied with magnetometry and ferromagnetic resonance as a function of film thickness. They maintain the colossal magnetoresistance behavior with a pronounced metal-insulator transition around 150-200 K, except for the very thinnest films studied (3 nm). Nevertheless, LCMO films as thin as 3 nm remain ferromagnetic, without a decrease in saturation magnetization, indicating an absence of dead-layers, although below approx. 6 nm the films remain insulating at low temperature. Magnetization hysteresis loops reveal that the magnetic easy axes lie in the plane of the film for thicknesses in the range of 4-15 nm. Ferromagnetic resonance studies confirm that the easy axes are in-plane, and find a biaxial symmetry in-plane with two, perpendicular easy axes. The directions of the easy axes with respect to the crystallographic directions of the cubic SrTiO3 substrate differ by 45 degrees in 4 nm and 15 nm thick LCMO films.Comment: Presented at Intermag conference (Madrid, 2008). Accepted for publication in IEEE Transactions on Magnetic

    Tailored Graphenic Structures Directly Grown on Titanium Oxide Boost the Interfacial Charge Transfer

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    The successful application of titanium oxide-graphene hybrids in the fields of photocatalysis, photovoltaics and photodetection strongly depends on the interfacial contact between both materials. The need to provide a good coupling between the enabling conductor and the photoactive phase prompted us to directly grow conducting graphenic structures on TiO2 crystals. We here report on the direct synthesis of tailored graphenic structures by using Plasma Assisted Chemical Vapour Deposition that present a clean junction with the prototypical titanium oxide (110) surface. Chemical analysis of the interface indicates chemical bonding between both materials. Photocurrent measurements under UV light illumination manifest that the charge transfer across the interface is efficient. Moreover, the influence of the synthesis atmosphere, gas precursor (C2H2) and diluents (Ar, O2), on the interface and on the structure of the as-grown graphenic material is assessed. The inclusion of O2 promotes vertical growth of partially oxidized carbon nanodots/rods with controllable height and density. The deposition with Ar results in continuous graphenic films with low resistivity (6.8x10-6 ohm x m). The synthesis protocols developed here are suitable to produce tailored carbon-semiconductor structures on a variety of practical substrates as thin films, pillars or nanoparticles.Comment: 24 pages, 8 figures, original research pape

    Direct Magnetic Evidence, Functionalization, and Low-Temperature Magneto-Electron Transport in Liquid-Phase Exfoliated FePS3

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    Magnetism and the existence of magnetic order in a material is determined by its dimensionality. In this regard, the recent emergence of magnetic layered van der Waals (vdW) materials provides a wide playground to explore the exotic magnetism arising in the two-dimensional (2D) limit. The magnetism of 2D flakes, especially antiferromagnetic ones, however, cannot be easily probed by conventional magnetometry techniques, being often replaced by indirect methods like Raman spectroscopy. Here, we make use of an alternative approach to provide direct magnetic evidence of few-layer vdW materials, including antiferromagnets. We take advantage of a surfactant-free, liquid-phase exfoliation (LPE) method to obtain thousands of few-layer FePS3 flakes that can be quenched in a solvent and measured in a conventional SQUID magnetometer. We show a direct magnetic evidence of the antiferromagnetic transition in FePS3 few-layer flakes, concomitant with a clear reduction of the Néel temperature with the flake thickness, in contrast with previous Raman reports. The quality of the LPE FePS3 flakes allows the study of electron transport down to cryogenic temperatures. The significant through-flake conductance is sensitive to the antiferromagnetic order transition. Besides, an additional rich spectra of electron transport excitations, including secondary magnetic transitions and potentially magnon-phonon hybrid states, appear at low temperatures. Finally, we show that the LPE is additionally a good starting point for the mass covalent functionalization of 2D magnetic materials with functional molecules. This technique is extensible to any vdW magnetic familyE.B. acknowledges funds from Ministerio de Ciencia e Innovación in Spain (RTI2018-096075-A-C22, RYC2019- 028429-I). E.M.P. thanks the Spanish Ministerio de Ciencia e Innovación (PID2020-116661RB-I00) and Comunidad de Madrid (P2018/NMT-4367). M.G.H. and A.C.-G. acknowledge funds from European Union Horizon 2020 research and innovation program (Graphene Core3-Grant agreement no. 881603 Graphene-based disruptive technologies), EU FLAGERA through the project To2Dox (JTC-2019-009), and Comunidad de Madrid through the project CAIRO-CM project (Y2020/NMT-6661). A.C.-G. also acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement no. 755655, ERC-StG 2017 project 2D-TOPSENSE) and the Ministry of Science and Innovation (Spain) through the project PID2020-115566RB-I00. M.L.R.G. acknowledges support by the Spanish Ministry of Science and Innovation through Research Project PID 2020- 113753RB-100. The National Centre for Electron Microscopy (ELECMI National Singular Scientific Facility) is also acknowledge for provision of access to corrected aberration microscopy facilities. CzechNanoLab Research Infrastructure supported by MEYS CR (LM2018110) is acknowledge

    Exploratory study of an oral screening dysplasia program for HIV-infected men who have sex with men

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    Dysplasia; Screening; HIV-infectedDisplasia; Cribado; Infectado por el VIHDisplàsia; Cribratge; Infectat pel VIHBackground: HIV-infected men who have sex with men (MSM) are at high risk to develop human papilloma virus (HPV)-related oropharyngeal cancer. The aim of our study was to assess the usefulness of a pilot oral dysplasia screening program and its correlation with an anal dysplasia screening program. Methods: This was a prospective study with HIV-infected MSM. Oral and anal screenings were performed based on HPV determination, liquid cytology, direct and microscopy oral examinations, high-resolution anoscopy and biopsies, if necessary. Results: A total of 103 patients were included. The mean age of the patients was 44.6 years, 55.3% were smokers, and 57.3% had a history of previous anal high-grade squamous intraepithelial lesions (HSILs). The prevalence of oral HPV infections was 14% (9% HPV-high risk), the prevalence of abnormal cytology was 25.2%, and in 4.8% of the patients, oral examinations showed suspicious HSILs. Oral microscopy did not detect additional lesions that visual inspection. Five oral biopsies were performed and the results were normal. No risk factors for oral HPV infections were identified. The prevalence of anal HPV infections was 88.3% (76.7% HPV-high risk), 52.9% of the patients had altered cytology, and in 45.6% anoscopy showed changes suggestive of HSILs. Seventy-two anal biopsies were performed, detecting 25 cases of HSILs (24.3%). A poor correlation was observed between oral and anal HPV infections (κ = 0.037). Conclusions: The prevalence of oral HPV infections, abnormal cytology and lesions in HIV-infected MSM was low, and their correlation with anal HPV-related lesions was slight. These results confirm the current barriers to oral dysplasia screening techniques.Study funded by program MISP of MSD (Merck HPV Investigator Study Program). MISP project code 58237

    Influence of the Human Development Index on the Maternal–Perinatal Morbidity and Mortality of Pregnant Women with SARS-CoV-2 Infection: Importance for Personalized Medical Care

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    This study (FIS-PI18/00912) was supported by the Instituto de Salud Carlos III (Plan Estatal de I + D + i 2013–2016) and cofinanced by the European Development Regional Fund ‘‘A way to achieve Europe’’ (ERDF) and B2017/BMD-3804 MITIC-CM.Coronavirus disease-19 (COVID-19) is perhaps the most worrisome pandemic in the 21st century, having entailed devastating consequences for the whole society during the last year. Different studies have displayed an existing association between pregnancy and COVID-19 severity due to the various physiological changes that occur during gestation. Recent data identified maternal country of origin as an important determinant of COVID-19 presentation in pregnant women. However, the explanation of this fact remains to be fully elucidated. Therefore, the purpose of this work is to analyze the possible relationship between Human Development Index (HDI) of maternal country of origin with the morbimortality of pregnant women and their newborns. Here, we conducted a multicentric, ambispective, observational case-control study (1:1 ratio) and compare with the HDI of each country (group 1—very high HDI, group 2—high HDI, group 3—medium HDI, and group 4—low HDI). In total, 1347 pregnant women with confirmed SARV-CoV-2 infection (cases) were enrolled, and each was paired with one control to give a total number of 2694 participants from 81 tertiary care centers. Among the women with SARS-CoV-2 infection, more cases were produced of perinatal mortality, overall maternal morbidity, COVID-19 maternal morbidity, C-sections, hypertensive maternal morbidity, and perinatal morbidity. Our results described an inverse association between HDI and maternofetal morbidity and mortality. Moreover, the countries with an HDI lower than 1 showed higher rates of patients with maternal COVID-19-related morbidity (6.0% vs. 2.4%, p < 0.001), a need for oxygen therapy (4.7% vs. 1.8%, p < 0.001), and maternal ICU admission (2.6% vs. 1.0%, p = 0.007). Compared to other risk factors such as overweight, obesity, preexisting and obstetric comorbidities, HDI emerged as an independent risk factor explaining much of the increased maternal–perinatal morbidity and mortality detected in our group of cases. Further research is needed to establish to confirm the real impact of this factor and its components on pregnancy outcomes.Depto. de Salud Pública y Materno - InfantilFac. de MedicinaTRUEUnión EuropeaComunidad de MadridInstituto de Salud Carlos IIIpu

    Particle-yield modification in jet-like azimuthal di-hadron correlations in Pb-Pb collisions at sNN\sqrt{s_{\rm NN}} = 2.76 TeV

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    The yield of charged particles associated with high-pTp_{\rm T} trigger particles (8<pT<158 < p_{\rm T} < 15 GeV/cc) is measured with the ALICE detector in Pb-Pb collisions at sNN\sqrt{s_{\rm NN}} = 2.76 TeV relative to proton-proton collisions at the same energy. The conditional per-trigger yields are extracted from the narrow jet-like correlation peaks in azimuthal di-hadron correlations. In the 5% most central collisions, we observe that the yield of associated charged particles with transverse momenta pT>3p_{\rm T}> 3 GeV/cc on the away-side drops to about 60% of that observed in pp collisions, while on the near-side a moderate enhancement of 20-30% is found.Comment: 15 pages, 2 captioned figures, 1 table, authors from page 10, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/350

    Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems

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    We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.Peer ReviewedPostprint (published version
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