Variability and power enhancement of current controlled resistive switching devices

Producción CientíficaIn this work, the unipolar resistive switching behaviour of Ni/HfO2/Si(n+) devices is studied. The structures are characterized using both current and voltage sweeps, with the device resistance and its cycle-to-cycle variability being analysed in each case. Experimental measurements indicate a clear improvement on resistance states stability when using current sweeps to induce both set and reset processes. Moreover, it has been found that using current to induce these transitions is more efficient than using voltage sweeps, as seen when analysing the device power consumption. The same results are obtained for devices with a Ni top electrode and a bilayer or pentalayer of HfO2/Al2O3 as dielectric. Finally, kinetic Monte Carlo and compact modelling simulation studies are performed to shed light on the experimental results.Junta de Andalucía - FEDER (B-TIC-624-UGR20)Consejo Superior de Investigaciones Científicas (CSIC) (project 20225AT012)Ramón y Cajal (grant RYC2020-030150-I

Adherencia bacteriana en los materiales de sutura de uso habitual en cirugía bucal. Revisión sistemática

Objetivo: Demostrar la existencia de agregación bacteriana a los materiales de sutura que suelen emplearse en la práctica odontológica, comprobar si dicha agregación está relacionada con la inflamación que sucede al acto quirúrgico y por último dar recomendaciones sobre qué tipo de sutura se adapta mejor para la prevención de la adherencia bacteriana. Material y método: Búsqueda bibliográfica a través de las bases de datos PubMed, Cochrane y Scielo empleando las palabras clave: surgical sutures, bacterial adherence. Como criterios de inclusión se aceptaron los estudios publicados en los últimos 15 años, in vivo o in vitro en relación con la cirugía oral y con un nivel de evidencia científico superior a 3 según los criterios de evidencia científica. Fueron excluidas todas aquellas publicaciones que no tenían como objeto de estudio las sutura seda, Nylon , Supramid , Monocryl , Vicryl o Vicryl Plus . También se excluyeron todas aquellas publicaciones que no relacionaban los materiales de sutura a la agregación bacteriana. Resultados: Un total de 9 publicaciones se organizaron en función del tipo de sutura empleada, si eran estudios in vivo o in vitro, el número de pacientes/muestras, tiempo transcurrido hasta la remoción de las suturas, si se realizaron controles, si existió algún tipo de reacción inflamatoria, que tipo de bacterias se agregaron y que material obtuvo mayor agregación. Discusión: Los materiales de sutura que mayor acúmulo de placa bacteriana presentan bajo las mismas condiciones de tiempo de exposición a bacterias, son los de tipo multifilamento reabsorbible no tratados con antimicrobianos

The strongly defective double perovskite Sr11M o4O23: Crystal structure in relation to ionic conductivity

The crystal structure and ionic conductivity properties of a novel microcrystalline Sr11Mo4O23 ceramic material are presented. This material has been prepared by thermal treatment up to 1473emK, in air, of previously decomposed citrate precursors. The complex crystal structure was refined from combined X-ray powder diffraction and neutron powder diffraction data. The formula of this phase can be rewritten as Sr1.75□ 0.25SrMoO5.75, highlighting the relationship with double perovskites A2 B′B′′O6. At room temperature, the crystal structure is tetragonal in space group I4 1/a, with a = 11.6107em(6)emÅ, c = 16.422em(1)emÅ and V = 2213.8em(2)emÅ3. The crystal network contains O anion and Sr cation vacancies. The structure is complex, with Sr, Mo and O atoms distributed over four, two and six distinct Wyckoff sites, respectively. Only one of the Sr sites (SrO6) corresponds to the octahedral network; one of the two MoO 6 types of octahedra is axially distorted. The three other Sr positions occupy the A site with higher coordination. There is an occupational deficit of O atoms of 22em(4)%. This defective framework material presents an interesting ionic mobility, enhanced above 773emK owing to a further reduction in the oxygen content.CP thanks CONICET (project Nos. PIP01360/08 and PIP00912/12) and SECyT-UNSL (project Nos. PROICO7707 and PROICO2-1612). DGL acknowledges ANPCyT for financial support (projects PICT2011 Nos. 1948 and 2689). JAA thanks the Spanish MICINN for funding via project No. MAT2013-41099-R

A Framework for User Adaptation and Profiling for Social Robotics in Rehabilitation

Physical rehabilitation therapies for children present a challenge, and its success—the improvement of the patient’s condition—depends on many factors, such as the patient’s attitude and motivation, the correct execution of the exercises prescribed by the specialist or his progressive recovery during the therapy. With the aim to increase the benefits of these therapies, social humanoid robots with a friendly aspect represent a promising tool not only to boost the interaction with the pediatric patient, but also to assist physicians in their work. To achieve both goals, it is essential to monitor in detail the patient’s condition, trying to generate user profile models which enhance the feedback with both the system and the specialist. This paper describes how the project NAOTherapist—a robotic architecture for rehabilitation with social robots—has been upgraded in order to include a monitoring system able to generate user profile models through the interaction with the patient, performing user-adapted therapies. Furthermore, the system has been improved by integrating a machine learning algorithm which recognizes the pose adopted by the patient and by adding a clinical reports generation system based on the QUEST metricThis work is partially funded by grant RTI2018-099522-B-C43 of FEDER/Ministerio de Ciencia e Innovación - Ministerio de Universidades - Agencia Estatal de Investigació

Coexistence of localized and itinerant electrons in the double-perovskite Ba2Fe2/3Mo4/3O6

A polycrystalline Ba2Fe2/3Mo4/3O 6 double-perovskite has been prepared by decomposition of citrate precursors and subsequent thermal treatment under a reducing atmosphere. The crystal structure has been studied by combined X-ray and neutron powder diffraction (XRPD and NPD). At room temperature, the structure is cubic (Fm3̄m) with lattice parameter a = 8.0710(1) Å. It is unchanged between 3 and 320 K. The crystallographic formula is Ba2[Fe 0.52(2)Mo0.48(2)]4a[Fe0.14(2)Mo 0.86(2)]4bO5.9(2). NPD, electron spin resonance (ESR), and magnetization measurements show spontaneous magnetization below the Curie temperature (TC) = 310 K. The ESR behavior is associated with the presence of localized Fe3+ ions, whereas the transport properties (electrical conductivity and Seebeck effect) suggest the presence of highly correlated electrons in a metallic band with disorder, which can be associated with the Mo t2g electrons. The coexistence of localized and itinerant electrons leads to non-negligible magnetoresistance properties.J. C. P. thanks Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (project PIP 112‐200801‐01360), Secretaría de Ciencia y Tecnología de la Universidad Nacional de San Luis (SECyT‐UNSL) (project PROICO 2‐7707‐22/Q823), and Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT) (project PICT 6/25459). R. D. S. thanks Universidad Nacional de Cuyo (UNCuyo), CONICET, and ANPCyT (Argentina) under grants 06/C389, PIP‐490, and PICT2007‐0832/PICT2011‐0752. J. C. P., R. D. S., C. A. L., and M. E. S. are members of CONICET. J. A. A. acknowledges the financial support of the Spanish Ministry of Education on the project MAT2007‐60536

Dicoumarol relieves serum withdrawal-induced G0/1 blockade in HL-60 cells through a superoxide-dependent mechanism

13 páginas, 10 figuras, 1 tabla.This work was set to study how dicoumarol affects the cell cycle in human myeloid leukemia HL-60 cells. Cells were accumulated in G0/1 after serum deprivation. However, when cells were treated with 5 μM dicoumarol in serum-free medium, a significant increment in the number of cells in S-phase was observed. Inhibition of G0/1 blockade was confirmed by the increase of thymidine incorporation, the phosphorylation of retinoblastoma protein, and the promotion of cell growth in long-term treatments in the absence of serum. Dicoumarol treatment increased superoxide levels, but did not affect peroxide. Increase of cellular superoxide was essential for inhibition of G0/1 blockade, since scavenging this reactive species with a cell-permeable form of SOD and the SOD mimetics 2-amino-3,5-dibromo-N-[trans-4-hydroxycyclohexyl]benzylamine (ambroxol, 100 μM) and copper[II]diisopropyl salicylate (CuDIPS, 10 μM) completely abolished the effect of dicoumarol. However, N-acetyl-cysteine, overexpression of Bcl-2 or a cell-permeable form of catalase were not effective. 5-Methoxy-1,2-dimethyl-3-[(4-nitrophenol)methyl]-indole-4,7-dione (ES936), a mechanism-based irreversible inhibitor of NAD(P)H:quinone oxidoreductase 1 (NQO1), did not promote S phase entry, and dicoumarol still inhibited G0/1 blockade in the presence of ES936. We demonstrate that dicoumarol inhibits the normal blockade in G0/1 in HL-60 cells through a mechanism involving superoxide, but this effect is not dependent solely on the inhibition of the NQO1 catalytic activity. Our results send a precautionary message about use of dicoumarol to elucidate cellular processes involving oxidoreductases.Supported by Grants No. BMC2002-01078 (Spanish Ministerio de Educación y Cultura and Ministerio de Ciencia y Tecnología) and CVI-276 (Junta de Andalucía). R.I.B. acknowledges financial support by the Spanish Ministerio de Educación y Cultura, CVI-276, and Instituto Danone. C.G.D. and M.C.C.-P. were supported by CVI-276. N.F. was granted by the French Association pour la Recherche sur le Cancer and by Junta de Andalucía.Peer reviewe

Localization and impact of Pb-non-bonded electronic pair on the crystal and electronic structure of Pb2YSbO6

The synthesis and crystal structure evolution of the double perovskite Pb2YSbO6 is reported for the first time. The structure has been analyzed in the temperature range between 100 and 500 K by using a combination of synchrotron and neutron powder diffraction. This compound shows two consecutive first order phase transformations as previously observed for a subgroup of Pb2RSbO6 perovkites (R = rare earths). The thermodynamic parameters associated with the phase transitions were calculated using differential scanning calorimetry (DSC), and the role of the diverse cations of the structure was studied from DFT calculations for the room temperature polymorph. The crystal structure evolves from a C2/c monoclinic structure (a-b-b- tilting system in Glazers notation) to another monoclinic P21/n (a-a -b+) phase with an incommensurate modulation and finally to a cubic Fm3̄m perovskite (a0a0a0). The highly distorted nature of the room temperature crystal structure seems to be driven by the polarization of the Pb lone pair which shows a marked local effect in the atomic spatial arrangements. Moreover, the lone pairs have been localized from DFT calculations and show an antiferroelectric ordering along the b monoclinic axis.S.A.L. acknowledges a CONICET fellowship. J.C.P. acknowledges CONICET (Project PIP 2008-01360) and SECyT-UNSL (Projects 7707 and 2-1612). J.C.P. is member of CONICET. J.A.A. acknowledges the financial support of the Spanish Ministry of Education to Project MAT2010-16404. V.A.P.O. acknowledges financial support from the MCYT in the Ramon y Cajal Program and ENE2009-09432