Role of age and comorbidities in mortality of patients with infective endocarditis

[Purpose]: The aim of this study was to analyse the characteristics of patients with IE in three groups of age and to assess the ability of age and the Charlson Comorbidity Index (CCI) to predict mortality. [Methods]: Prospective cohort study of all patients with IE included in the GAMES Spanish database between 2008 and 2015.Patients were stratified into three age groups:<65 years,65 to 80 years,and ≥ 80 years.The area under the receiver-operating characteristic (AUROC) curve was calculated to quantify the diagnostic accuracy of the CCI to predict mortality risk. [Results]: A total of 3120 patients with IE (1327 < 65 years;1291 65-80 years;502 ≥ 80 years) were enrolled.Fever and heart failure were the most common presentations of IE, with no differences among age groups.Patients ≥80 years who underwent surgery were significantly lower compared with other age groups (14.3%,65 years; 20.5%,65-79 years; 31.3%,≥80 years). In-hospital mortality was lower in the <65-year group (20.3%,<65 years;30.1%,65-79 years;34.7%,≥80 years;p < 0.001) as well as 1-year mortality (3.2%, <65 years; 5.5%, 65-80 years;7.6%,≥80 years; p = 0.003).Independent predictors of mortality were age ≥ 80 years (hazard ratio [HR]:2.78;95% confidence interval [CI]:2.32–3.34), CCI ≥ 3 (HR:1.62; 95% CI:1.39–1.88),and non-performed surgery (HR:1.64;95% CI:11.16–1.58).When the three age groups were compared,the AUROC curve for CCI was significantly larger for patients aged <65 years(p < 0.001) for both in-hospital and 1-year mortality. [Conclusion]: There were no differences in the clinical presentation of IE between the groups. Age ≥ 80 years, high comorbidity (measured by CCI),and non-performance of surgery were independent predictors of mortality in patients with IE.CCI could help to identify those patients with IE and surgical indication who present a lower risk of in-hospital and 1-year mortality after surgery, especially in the <65-year group

Advances in Magnetic Force Microscopy

Tesis leída en la universidad Autónoma de Madrid para conseguir el título de Doctor en Filosofía.-- Calificación: Cum Laude[ES] La piedra angular sobre la que se basa esta tesis es la microscopía de fuerza magnética y su uso para extraer información añadida del estudio de muestras ferromagnéticas. A lo largo del manuscrito, se ha estudiado una extensa variedad de materiales. Éste está dividido en cinco capítulos, cada uno de los cuales se centra en una temática diferente. Si bien aconsejamos seguir el orden establecido, el manuscrito está escrito de tal forma que el lector pueda leer cada capítulo de manera independiente. En algunas partes específicas se hace referencia a otros capítulos, en los que se comenta en más detalle algún asunto en particular.[EN] The cornerstone of this thesis is the use of magnetic force microscopy to extract added information from ferromagnetic samples. An extensive variety of materials has been studied and is reported throughout the manuscript. It is divided in five chapters, each of which is devoted to a different subject. Although we recommend following the established order, the manuscript is written in such a way that the reader can read any chapter independently. At some specific points, reference to other chapters is pointed out, where more detail about a particular issue is given.Peer reviewe

Effect of using stencil masks made by focused ion beam milling on permalloy (Ni81Fe19) nanostructures

Focused ion beam (FIB) milling is a common fabrication technique to make nanostencil masks which has the unintended consequence of gallium ion implantation surrounding milled features in silicon nitride membranes. We observe major changes in film structure, chemical composition, and magnetic behaviour of permalloy nanostructures deposited by electron beam evaporation using silicon nitride stencil masks made by a FIB as compared to stencil masks made by regular lithography techniques. We characterize the stenciled structures and both types of masks using transmission electron microscopy, electron energy loss spectroscopy, energy dispersive x-ray spectroscopy, magnetic force microscopy and kelvin probe force microscopy. All these techniques demonstrate distinct differences at a length scale of a 1-100 nm for the structures made using stencil mask fabricated using a FIB. The origin of these differences seems to be related to the presence of implanted ions, a detailed understanding of the mechanism however remains to be developed. © 2013 IOP Publishing Ltd.Peer Reviewe

Magnetic imaging of nanostructures

Oral presentation given at the Nano and giga challenges in electronics, photonics and renewable energy: from materials to devices to system architecture (2014), held in Phoenix (Arizona, United States) on March 10-14th 2014. The presentation took place in the Nanotechnology instrumentation workshop.In the last few decades a number of powerful magnetic characterization tools have been developed with resolutions ranging from the micrometer scale down to the atomic level. Furthermore, many of these techniques are complementary to each other, since they are sensitive to different properties of the sample. The development and optimization of magnetic materials requires the knowledge of magnetic domains and their reaction to magnetic fields, which, in most cases, can only be gained by direct imaging. The study of the domain configuration in magnetic nanostructures is of decisive importance since they present as valuable candidates for the development of high-density storage media, high-speed magnetic random access memories, nanoelectromechanical systems NEMS, and magnetic sensors and logic devices. Nanoelements exhibit different magnetic behavior as a function of their crystalline structure, size, aspect ratio, and separations in case of arrays of nanomagnets. A number of different techniques are currently employed to observe magnetic domains and walls at nanoscale: magneto-optic Kerr effect (nano-MOKE) µSQUID, Spin Polarized Scanning Tunneling Microscopy, X-ray Magnetic Circular Dichroism (XMCD) or Lorentz-TEM and Magnetic Force Microscopy (MFM). Among them, the advantages of the MFM compared with the other local magnetic characterization techniques are its high spatial resolution, simplicity in sample preparation, RT working conditions, the capability to applied external magnetic fields and the acquisition of additional information about the surface properties of the sample. More than 20 years after its invention, the MFM has become a widespread tool to characterize magnetic materials. In this work we show the usefulness of the MFM to characterize the magnetic configuration of different kind of magnetic nanostructures in remanence. In addition, we have developed new MFM-based techniques in order to improve the MFM capabilities. The Variable-Field MFM [1] allows to perform MFM measurements under variable magnetic fields in order to gain information about reversal magnetization processes [2-5]. In particular, the hysteresis loops of MFM probes and individual magnetic nanostructures [6] have been obtained. We have demonstrated the utility of the combination of Kelvin Probe Force Microscopy (KPFM) and MFM techniques to distinguish the electrostatic and magnetic tip-sample forces. Moreover, the split of both contributions in real time is crucial to study carbon-based materials [7,8] and devices [9]

Customized MFM probes with high lateral resolution

Magnetic force microscopy (MFM) is a widely used technique for magnetic imaging. Besides its advantages such as the high spatial resolution and the easy use in the characterization of relevant applied materials, the main handicaps of the technique are the lack of control over the tip stray field and poor lateral resolution when working under standard conditions. In this work, we present a convenient route to prepare high-performance MFM probes with sub-10 nm (sub-25 nm) topographic (magnetic) lateral resolution by following an easy and quick low-cost approach. This allows one to not only customize the tip stray field, avoiding tip-induced changes in the sample magnetization, but also to optimize MFM imaging in vacuum (or liquid media) by choosing tips mounted on hard (or soft) cantilevers, a technology that is currently not available on the market

Tip-induced artifacts in magnetic force microscopy images

Useful sample information can be extracted from the dissipation in frequency modulation atomic force microscopy due to its correlation to important material properties. It has been recently shown that artifacts can often be observed in the dissipation channel, due to the spurious mechanical resonances of the atomic force microscope instrument when the oscillation frequency of the force sensor changes. In this paper, we present another source of instrumental artifacts specific to magnetic force microscopy (MFM), which is attributed to a magnetization switching happening at the apex of MFM tips. These artifacts can cause a misinterpretation of the domain structure in MFM images of magnetic samples. © 2013 American Institute of Physics.Funding from NSERC, FQRN, and CIfAR is acknowledged. A.A. and O.I.-F. acknowledge financial support from projects CSD2010-00024 (MEC) and S2009/MAT-1467 (CAM), and MICINN.Peer Reviewe

Customized MFM probes with high lateral resolution Full Research Paper Open Access

Abstract Magnetic force microscopy (MFM) is a widely used technique for magnetic imaging. Besides its advantages such as the high spatial resolution and the easy use in the characterization of relevant applied materials, the main handicaps of the technique are the lack of control over the tip stray field and poor lateral resolution when working under standard conditions. In this work, we present a convenient route to prepare high-performance MFM probes with sub-10 nm (sub-25 nm) topographic (magnetic) lateral resolution by following an easy and quick low-cost approach. This allows one to not only customize the tip stray field, avoiding tip-induced changes in the sample magnetization, but also to optimize MFM imaging in vacuum (or liquid media) by choosing tips mounted on hard (or soft) cantilevers, a technology that is currently not available on the market. 106

Magnetic scanning probe calibration using graphene hall sensor

Magnetic force microscopy (MFM) offers a unique insight into the nanoscopic scale domain structures of magnetic materials. However, MFM is generally regarded as a qualitative technique and, therefore, requires meticulous calibration of the magnetic scanning probe stray field (Bprobe) for quantitative measurements. We present a straightforward calibration of B probe using scanning gate microscopy on epitaxial graphene Hall sensor in conjunction with Kelvin probe force microscopy feedback loop to eliminate sample-probe parasitic electric field interactions. Using this technique, we determined Bprobe ∼ 70 mT and ∼ 76 mT for probes with nominal magnetic moment ∼ 1 × 10-13 and > 3 × 10-13 emu, respectively, at a probe-sample distance of 20 nm. © 2013 IEEE.This work was partly supported by projects Concept Graphene, IRD Graphene, MetMags and CSD2010-00024.Peer Reviewe

Customized MFM probes with high lateral resolution

Magnetic force microscopy (MFM) is a widely used technique for magnetic imaging. Besides its advantages such as the high spatial resolution and the easy use in the characterization of relevant applied materials, the main handicaps of the technique are the lack of control over the tip stray field and poor lateral resolution when working under standard conditions. In this work, we present a convenient route to prepare high-performance MFM probes with sub-10 nm (sub-25 nm) topographic (magnetic) lateral resolution by following an easy and quick low-cost approach. This allows one to not only customize the tip stray field, avoiding tip-induced changes in the sample magnetization, but also to optimize MFM imaging in vacuum (or liquid media) by choosing tips mounted on hard (or soft) cantilevers, a technology that is currently not available on the market.This work was supported by grants CSD2010-00024 and MAT2013-48054-C2 from MINECO (Spain).Peer reviewe

Pressure effects in hollow and solid iron oxide nanoparticles

arXiv:1301.5708v1We report a study on the pressure response of the anisotropy energy of hollow and solid maghemite nanoparticles. The differences between the maghemite samples are understood in terms of size, magnetic anisotropy and shape of the particles. In particular, the differences between hollow and solid samples are due to the different shape of the nanoparticles and by comparing both pressure responses it is possible to conclude that the shell has a larger pressure response when compared to the core. © 2013 Elsevier B.V.The Aveiro–Barcelona collaboration has been supported by the Integrated Spanish–Portuguese Action under the Grant no. AIB2010PT-00099. The Aveiro–Zaragoza collaboration has been supported by the Integrated Spanish–Portuguese ActionPT2009-0131. The work in Zaragoza has been supported by the research Grants MAT2011-27233-C02-02, MAT2011-25991 and CONSOLIDER CSD2007-00010 from the Ministry of Education. The financial support of the CSIC and Spanish Ministerio de Ciencia e Innovación (PI201060E013) is also acknowledged. The work in Japan was supported by a Grant-in-Aid for Scientific Research (C) (No. 23550158) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. Ò.I. and A.L. acknowledge funding of the Spanish MICINN through Grant nos. MAT2009-08667 and CSD2006-00012, and Catalan DIUE through Project no. 2009SGR856. N.J.O.S. acknowledges FCT for Ciencia 2008 program.Peer Reviewe