Dual encoding of muscle tension and eye position by abducens motoneurons

Extraocular muscle tension associated with spontaneous eye movements has a pulse-slide-step profile similar to that of motoneuron firing rate. Existing models only relate motoneuron firing to eye position, velocity and acceleration. We measured and quantitatively compared lateral rectus muscle force and eye position with the firing of abducens motoneurons in the cat to determine fundamental encoding correlations. During fixations (step), muscle force increased exponentially with eccentric eye position, consistent with a model of estimate ensemble motor innervation based on neuronal sensitivities and recruitment order. Moreover, firing rate in all motoneurons tested was better related to eye position than to muscle tension during fixations. In contrast, during the postsaccadic slide phase, the time constant of firing rate decay was closely related to that of muscle force decay, suggesting that all motoneurons encode muscle tension as well. Discharge characteristics of abducens motoneurons formed overlapping clusters of phasic and tonic motoneurons, thus, tonic units recruited earlier and had a larger slide signal. We conclude that the slide signal is a discharge characteristic of the motoneuron that controls muscle tension during the postsaccadic phase and that motoneurons are specialized for both tension and position-related properties. The organization of signal content in the pool of abducens motoneurons from the very phasic to the very tonic units is possibly a result of the differential trophic background received from distinct types of muscle fibers

Comportamiento mecánico en función de la temperatura de aleaciones wolfranio-vanadio

Libro de proceedings de: XI Congreso Nacional de Materiales, Zaragoza, 23 junio 2010En esta investigación se evalúa el comportamiento mecánico del wolframio puro y de dos de sus aleaciones con contenidos de 2% y 4% de vanadio, fabricadas mediante prensado isostático en caliente (HIP). La caracterización mecánica se ha realizado mediante ensayos de flexión en tres puntos en atmósfera oxidante a distintas temperaturas comprendidas entre temperatura ambiente y 1000 ºC. Adicionalmente, se han realizado ensayos en inmersión en nitrógeno líquido para los de -197 ºC. Estos últimos valores pueden servir para una determinación más precisa de la temperatura la transición dúctil-frágil en éstos materiales, y de su posible comportamiento plástico o frágil a temperatura ambiente. Mediante estos ensayos ha sido posible obtener la tenacidad de fractura, la resistencia mecánica, el límite elástico y el módulo de elasticidad en función de la temperatura. Así mismo, se ha determinado la densidad y la dureza Vickers para dos cargas distintas, lo que permitido determinar la influencia de este parámetro en la medida realizada. Adicionalmente, se han examinado mediante microscopia electrónica de barrido las superficies de fractura. De esta forma ha sido posible determinar el modo de rotura y analizar la relación de las propiedades mecánicas macroscópicas con los micromecanismos de fallo involucrados.Este trabajo ha sido financiado por EFDA/CIEMAT WP08-09-MAT-WWALLOY, Ministerio de Ciencia e Innovación, MAT2007-29278-E, BIA2004-04835, y MAT2009- 13979-C03-02, y Comunidad de Madrid, SS2009/MAT-1585 y S2009/ENE-1679Publicad

Two-phase SPH modelling of a real debris avalanche and analysis of its impact on bottom drainage screens

Rapid flow-like landslides, particularly debris flows and debris avalanches, cause significant economic damage and many victims worldwide every year. They are usually extremely fast with the capability of travelling long distances in short times, sweeping away everything in their path. The principal objective of this paper is to test the ability of the ‘GeoFlow-SPH’ two-phase model developed by the authors, to reproduce the complex behaviour of natural debris avalanches where pore-water pressure evolution plays a key role. To reach this goal, the model is applied to reproduce the complex dynamic behaviour observed in Johnsons Landing debris avalanche including the observed bifurcation caused by the flowing out of part of the moving mass from the mid-channel. Initial thickness deposit trim-line, distribution of deposit volume, and the average velocities were provided for this real case, making it an appropriate case to validate the developed model. The paper also contributes to evaluate the SPH-FD model’s potentialities to simulate the structural countermeasure, like bottom drainage screens, used to reduce the impact of debris flows. The analysis of the results shows the adequacy of the proposed model to solve this complicated geophysical problem.Fil: Tayyebi, Saeid M.. Universidad Politécnica de Madrid; EspañaFil: Pastor, Manuel. Universidad Politécnica de Madrid; EspañaFil: Stickle, Miguel M.. Universidad Politécnica de Madrid; EspañaFil: Yagüe, Ángel. Universidad Politécnica de Madrid; EspañaFil: Manzanal, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentina. Universidad Politécnica de Madrid; EspañaFil: Molinos, Miguel. Universidad Politécnica de Madrid; EspañaFil: Navas, Pedro. Universidad Politécnica de Madrid; Españ

Influencia de la composición y microestructura sobre las propiedades mecánicas de aleaciones de wolframio

Comunicaciones presentadas en: XXVI Encuentro del Grupo Español de Fractura, Santander, 25 marzo 2009.En esta investigación se estudia la influencia de la microestructura en el comportamiento mecánico del wolframio puro y aleaciones con contenidos de 0.5% de Y₂O₃ y 4% de Ti, todos ellos obtenidos mediante HIP. Con el fin de correlacionar el comportamiento macroscópico con los parámetros microestructurales, se ha analizado mediante microscopía óptica y electrónica de barrido, la microestructura y las superficies de fractura muestras ensayadas en flexión en tres puntos a diferentes temperaturas (entre 25 y 1000 °C). La medida del tamaño de grano de las muestras se ha realizado, de acuerdo con la norma ASTM E112, mediante un programa de análisis de imagen. Los resultados muestran que la adición de titanio al wolframio mejora las propiedades del material al obtenerse éste exento de porosidad. La formación de una solución sólida, y la estructura de tamaño de grano más fina, aumentan la resistencia mecánica del material hasta temperaturas superiores a 600 °C. Por otra parte la adición de itria comportamiento mecánico del wolframio puro a altas temperaturas, evitando la oxidación, pero no modifica sustancialmente el tamaño de grano obtenido bajo las condiciones de fabricación, debido a la formación de fases eutécticas.In this research the influence of the microstructure in the mechanical behaviour of pure tungsten and its alloys with 0.5% of yttrium oxide and 4% titanium contents, all of them manufactured by HIP, is considered. The microstructure and fracture surfaces of the samples tested in three points bending at different temperatures (between 25 and 1000 ºC) are studied by optical microscopy and SEM, in order to relation the macroscopic behaviour with the microstructural analyzed parameters. The size grain has been measured according to ASTM E112 code, using a image analysis software. The results show that the addition of titanium to the pure tungsten lets manufacture a material without pores improving its mechanical properties. The solid solution, and refined grain structure obtained in these materials, raised the mechanical behaviour up to 600 ºC. The yttrium oxide addition improved the mechanical properties at high temperatures respect to pure tungsten, and avoids oxidation. Nevertheless, this does not modify substantially the grain size obtained in the manufacturing conditions due to the eutectic constituent formation.Proyecto financiado por el Ministerio de Ciencia e Innovación en virtud de los proyectos MAT2006‐13005‐C03‐02, MAT2007‐29278‐E, y CSD00C-06-14102, por la Comunidad de Madrid a través del programa ESTRUMAT-CM (S-0505/MAT/0077) y por la Asociación EURATOM/CIEMAT/EFDA a través del contrato TW6-TTMA-002-EFDA.Publicad

Sexual Dysfunction and Quality of Life in Chronic Heroin-Dependent Individuals on Methadone Maintenance Treatment.

Agradecimiento: El artículo está publicado en la revista Journal of Clinical Medicine [MDPI] y disponible en: https://www.mdpi.com/2077-0383/8/3/321[EN]This study examined whether methadone (hereinafter referred to as MTD) maintenance treatment (MMT) is correlated with sexual dysfunction (SD) in heroin-dependent men. This was conducted to determine the prevalence of sexual dysfunction and if there is a relationship between duration and dose among men on MMT and its impact on the quality of life. The study combined a retrospective and a cross-sectional survey based on the Kinsey Scale, TECVASP, and PRSexDQ-SALSEX clinical interviews of 85 patients who are currently engaged in MMT. Sexual dysfunction in all five PRSexDQ-SALSEX domains (lack of libido, delay in orgasm, inability to orgasm, erectile dysfunction, and tolerance or acceptance of changes in sexual function) was associated with dose and long-term use of heroin. All dimensions of SD were affected by the MTD intake. From the analysis of our sample, we may conclude that dose of MTD and overall score of SD were directly associated. However, no evidence was found to prove that treatment duration and severity of SD were linked. It is notable that only one tenth of the patients spontaneously reported their symptoms of the sexual sphere, but up to a third considered leaving the MMT for this reason

Proton conductivity of multifunctional metal phosphonate frameworks

Metal phosphonates exhibit attractive characteristics for proton conductivity, such as tunable functionality, chemical and thermal stability and the existence of H-bond networks with acidic protons within their structure.1 In the present work, we examine the relationship between crystal structure and proton conductivity for several metal (mono-, di- and tri-valent) phosphonates containing rigid: (5-(dihydroxyphosphoryl)isophthalic acid, PiPhtA and 2-hydroxyphosphonoacetic acid, HPAA) or flexible: (hexa- or octamethylenediamine-N,N,N′,N′-tetrakis(methylenephosphonic acid, H8HDTMP or H8ODTMP) multifunctional ligands. The crystalline hybrid derivatives prepared show a great structural diversity, from 1D to 3D open-frameworks possessing hydrogen-bonded water molecules and phosphonic and carboxylic acid groups. The rigid 3D framework of Ca-PiPhtA, that exhibits a proton conductivity of 5.7•10-4 S/cm as synthesized, transforms into a layered compound upon exposure to ammonia vapors2 with increased proton conductivity (6.6•10-3 S/cm). The flexible frameworks of magnesium or lanthanide phosphonates, with 1D channels, present conductivities higher than 10-3 S/cm. Their activation energies fall in the range corresponding to a Grotthuss mechanism.3,4 For M(I)-HPAA solids conductivities up to 5.6•10-3 S/cm were measured. References 1. P. Ramaswamy, N.E. Wong, G.K.H. Shimizu, Chem. Soc. Rev. 43 (2014) 5913. 2. M. Bazaga-García, R.M.P. Colodrero, M. Papadaki, P. Garczarek, J. Zoń, P. Olivera-Pastor, E.R. Losilla, L. León-Reina, M.A.G. Aranda, D. Choquesillo-Lazarte, K.D. Demadis, A. Cabeza, J. Amer. Chem. Soc. 136 (2014) 5731. 3. R.M.P. Colodrero, P. Olivera-Pastor, E.R. Losilla, D. Hernández-Alonso, M.A.G. Aranda, L. Leon-Reina, J. Rius, K.D. Demadis, B. Moreau, D. Villemin, M. Palomino, F. Rey, A. Cabeza, Inorg. Chem. 51 (2012) 7689. 4. R.M.P. Colodrero, P. Olivera-Pastor, E.R. Losilla, M.A.G. Aranda, L. Leon-Reina, M. Papadaki, A.C. McKinlay, R.E. Morris, K.D. Demadis, A. Cabeza, Dalton Trans. 41 (2012) 4045.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Junta de Andalucía, Proyecto Excelencia FQM-1656. Ministerio de Economía y Competitividad, MAT2013-41836-

Elemental speciation by capillary electrophoresis with inductively coupled plasma spectrometry: A new approach by flow focusing® nebulization

A novel system for Capillary Electrophoresis (CE) and Inductively Coupled Plasma (ICP) sample introduction that incorporates a dedicated Flow-Focusing® based nebulizer as aerosol generation unit is presented, aiming to provide high signal sensitivity and low detection limits for element speciation at short analysis times. To prove its viability, the system prototype constructed has been coupled to an inductively coupled plasma - optical emission spectrometer (ICP-OES) and an inductively coupled plasma - mass spectrometer (ICP-MS) for Cr(III) and Cr(VI) speciation. Separation - nebulization system and operation parameters (i.e., capillary length, nebulizer geometry, carrier flow, carrier ionic strength, separation potential and sample injection volume) have been considered and studied, and the analytical figures of merit obtained for model samples in ICP-MS are presented. The results obtained show that the developed instrumental system permits Cr speciation in less than two minutes with detection limits of 0.1, 0.2 and 0.03 μg/L for Cr(III), Cr(VI) and total Cr, respectively.The authors are grateful to the Spanish Government (project CTQ2008-06730-C02-01), the Valencian Government (project ACOMP/2010/047), the NSF of Bulgaria (project DO 02-07 GAMMA) and the European Commission (EC FP7 24588 BioSupport project) for the financial support

Structural Mapping and Framework Interconversions in 1D, 2D, and 3D Divalent Metal R,S-Hydroxyphosphonoacetate Hybrids

Reactions of divalent cations (Mg2þ, Co2þ, Ni2þ, and Zn2þ) with R,S-hydroxyphosphonoacetic acid (HPAA) in aqueous solutions (pH values ranging 1.0-4.0) yielded a range of crystalline hydrated M-HPAA hybrids. Onedimensional (1D) chain compounds were formed at room temperature whereas reactions conducted under hydrothermal conditions resulted in two-dimensional (2D) layered frameworks or, in some cases, three-dimensional (3D) networks incorporating various alkaline cations. 1D phases with compositions [M{HO3PCH(OH)CO2}(H2O)2]· 2H2O (M = Mg, Co, and Zn) were isolated. These compounds were dehydrated in liquid water to yield the corresponding [M{HO3PCH(OH)CO2}(H2O)2] compounds lacking the lattice water between the 1D chains. [M{HO3PCH(OH)CO2}(H2O)2] (M = Mg, Ni, Co, Zn) compounds were formed by crystallization at room temperature (at higher pH values) or also by partial dehydration of 1D compounds with higher hydration degrees. Complete dehydration of these 1D solids at 240-270 ºC led to 3D phases, [M{HO3PCH(OH)CO2}]. The 2D layered compound [Mg{HO3PCH(OH)CO2}(H2O)2] was obtained under hydrothermal conditions. For both synthesis methods, addition of alkali metal hydroxides to adjust the pH usually led to mixed phase materials, whereas direct reactions between the metal oxides and the hydroxyphosphonoacetic acid gave single phase materials. On the other hand, adjusting the pH with acetate salts and increasing the ratio M2þ/HPAA and/or the Aþ/M2þ ratio (A = Na, K) resulted in 3D networks, where the alkali cations were incorporated within the frameworks for charge compensation. The crystal structures of eight new M(II)-HPAA hybrids are reported herein and the thermal behavior related to dehydration/rehydration of some compounds are studied in detail.Proyecto nacional MAT2006-11080-C02-0

Glycerol Valorization towards a Benzoxazine Derivative through a Milling and Microwave Sequential Strategy

Glycerol and aminophenol intermolecular condensation has been investigated through a milling and microwave-assisted sequential strategy, towards the synthesis of a benzoxaxine derivative. Mechanochemical activation prior to the microwave-assisted process could improve the probability of contact between the reagents, and greatly favors the higher conversion of aminophenol. At the same time, following a mechanochemical–microwave sequential approach could tune the selectivity towards the formation of a benzoxazine derivative, which could find application in a wide range of biomedical area