130,940 research outputs found
A photoelectron spectroscopy study of sub-monolayer V/TiO2(001) interfaces annealed from 300 up to 623 K
No full textUPS and XPS measurements performed after in-situ thermal treatments show unambiguous and reproducible changes of these spectral components. After annealing at 623 K only the higher binding energy component is present in the V 2p(3/2) spectra; the Ti 2(p) core lines recover the typical symmetry of the clean and stoichiometric TiO2(001) surface and the higher binding energy feature only is detected in the TiO2 band gap. These data suggest that, within the volume probed by XPS and UPS, Ti ions have a mainly d(0) configuration, while V has a single and stable open-shell configuration, as revealed by the significant intensity detected within the TiO2 band gap. These annealing-induced changes are due, as suggested by the O 1s/Ti 2p core line intensity trend, to an oxygen diffusion from the TiO2 bulk to the surface. Finally, a detailed analysis of the data indicates that different V/TiO2(001) interfaces exhibit different behaviours after annealing treatments, depending on Theta(V). For Theta(V)=0.7 ML, V interdiffuses into the TiO2 sub-surface layers, whereas for Theta(V)=0.2 ML it remains at the surface. This finding is consistent with a rearrangement of V atoms, which under annealing occupy first the energetically most favorable surface sites (Theta(V) = 0.2 ML) before interdiffusing into the TiO2 lattice (Theta(V) = 0.7 ML)
Traumatic brain injury and translational research: pharmacological and nonpharmacological perspectives
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Ten rules for optimizing ventilatory settings and targets in post-cardiac arrest patients
No full textCardiac arrest (CA) is a major cause of morbidity and mortality frequently associated with neurological and systemic involvement. Supportive therapeutic strategies such as mechanical ventilation, hemodynamic settings, and temperature management have been implemented in the last decade in post-CA patients, aiming at protecting both the brain and the lungs and preventing systemic complications. A lung-protective ventilator strategy is currently the standard of care among critically ill patients since it demonstrated beneficial effects on mortality, ventilator-free days, and other clinical outcomes. The role of protective and personalized mechanical ventilation setting in patients without acute respiratory distress syndrome and after CA is becoming more evident. The individual effect of different parameters of lung-protective ventilation, including mechanical power as well as the optimal oxygen and carbon dioxide targets, on clinical outcomes is a matter of debate in post-CA patients. The management of hemodynamics and temperature in post-CA patients represents critical steps for obtaining clinical improvement. The aim of this review is to summarize and discuss current evidence on how to optimize mechanical ventilation in post-CA patients. We will provide ten tips and key insights to apply a lung-protective ventilator strategy in post-CA patients, considering the interplay between the lungs and other systems and organs, including the brain
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Optimal scheduling and real-time control of a microgrid with an electrolyzer and a fuel cell systems using a reference governor approach
No full textThis paper proposes a novel approach for the optimal scheduling and control of a microgrid with an electrolyzer and fuel cell systems, both of proton exchange membrane (PEM) technology. It is based on a hierarchical procedure constituted of two levels of optimization: a higher level based on an economic optimization for the optimal scheduling of different components of the microgrid, and a lower level for the real-time control of the hydrogen systems: PEM electrolyzer (PEMEZ) and PEM fuel cell (PEMFC). The flexible operation imposed by the higher level leads to a violation of the limits designed by the manufacturer of the hydrogen components, specifically when switching from one power level to another. The current proportional-integral (PI) controllers integrated into those systems cannot handle this issue, which provokes a premature aging phenomenon of the materials and leads to poor performance of the systems. In the present paper, at the lower level, a reference governor (RG) real-time control approach has been added on top of the PI controller to ensure the respect of the operating limits and guarantee better performances. The focus has been given to the stack's temperature in both the electrolyzer and fuel cell systems as the control objective because of its direct influence on the material's durability and, by extension, on the efficiency. The bi-level optimization and control architecture has been applied and validated through simulations using data from a real-world case study, specifically the Savona Campus Smart Polygeneration Microgrid in Italy. The results showed a significant reduction in the overshoots of the stack's temperature compared to the PI controller
On the slope filtration of [phi]-modules over the Robba ring
No full textThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 2008.In title on title page, [phi] appears as lower case Greek letter.Includes bibliographical references (leaves 63-65).Given a p-adic representation of the Galois group of a local field, we show that its Galois cohomology can be computed using the associated étale ([phi], [Gamma])-module over the Robba ring; this is a variant of a result of Herr. We then establish analogues, for not necessarily étale (([phi], [Gamma])-modules over the Robba ring, of the Euler-Poincaré characteristic formula and Tate local duality for p-adic representations. These results are expected to intervene in the duality theory for Selmer groups associated to de Rham representations. We introduce the notion of families of [phi]-modules which arises naturally from both rigid cohomology and p-adic Hodge theory. We then prove the local constancy of generic HN-polygons of families of overconvergent [phi]-modules and the semicontinuity of HN-polygons of families of [phi]-modules over reduced affinoid algebras. These results are prospective for a slope theory of families of (overconvergent) [phi]-modules.by Ruochuan Liu.Ph.D
This paper reports an X-ray photoemission study (XPS) of the core levels and the valence band of vanadia-titania catalysts and their precursor oxides. The XPS spectra of the vanadium core levels indicate that surface vanadium atoms are present with different oxidation states. Furthermore, it is demonstrated, for the first time, that the electronic states observed in the XPS valence-band spectra between the Fermi edge and the O 2p bands have mainly a V 3d character.
No full textThis paper reports an X-ray photoemission study (XPS) of the core levels and the valence band of vanadia-titania catalysts and their precursor oxides. The XPS spectra of the vanadium core levels indicate that surface vanadium atoms are present with different oxidation states. Furthermore, it is demonstrated, for the first time, that the electronic states observed in the XPS valence-band spectra between the Fermi edge and the O 2p bands have mainly a V 3d character
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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