110 research outputs found
Electrochemical Estimation of the Corrosion Rate of Magnesium/Aluminium Alloys
The corrosion rate of AZ31, AZ80, and AZ91D magnesium/aluminium alloys immersed in 3.5 wt.% NaCl was determined comparing gravimetric and electrochemical measurements. The findings revealed that, for all investigated materials, a fraction of the metallic surface exposed to the corrosive medium did not reveal a normal electrochemical response to the applied signal. This may be associated with phenomena such as partial disintegration of specimens into fine metallic particles, electrochemical formation of ions, and/or anomalous chemical attack occurring simultaneously with the normal electrochemical corrosion attack. The abnormal electrochemical behaviour was more evident for lower amounts of aluminium in the bulk composition of the investigated materials. Thus, the electrochemical estimates of pure Mg and the AZ31 alloy were not reliable and tended to underestimate corrosion losses.Peer Reviewe
Bibliotecas abiertas. El programa de visitas de la Biblioteca Valenciana Nicolau Primitiu
En un contexto de reducción de la financiación pública y de cambio de paradigma en
el acceso a la información, la supervivencia de las bibliotecas está ligada a un mayor
y mejor conocimiento de la ciudadanía de sus colecciones, productos y servicios. En
este estudio se analiza el programa de visitas de la Biblioteca Valenciana Nicolau
Primitiu, sus características, destinatarios y tipologías, así como los resultados
alcanzados hasta ahora.In a context of reduced public funding and a paradigm shift in access to information,
the survival of libraries is linked to greater and better knowledge by citizens of their
collections, products, and services. This study analyzes the visits program of the
Biblioteca Valenciana Nicolau Primitiu, its characteristics, recipients, and typologies,
as well as the results achieved so fa
Linear models of activation cascades: analytical solutions and coarse-graining of delayed signal transduction
Cellular signal transduction usually involves activation cascades, the
sequential activation of a series of proteins following the reception of an
input signal. Here we study the classic model of weakly activated cascades and
obtain analytical solutions for a variety of inputs. We show that in the
special but important case of optimal-gain cascades (i.e., when the
deactivation rates are identical) the downstream output of the cascade can be
represented exactly as a lumped nonlinear module containing an incomplete gamma
function with real parameters that depend on the rates and length of the
cascade, as well as parameters of the input signal. The expressions obtained
can be applied to the non-identical case when the deactivation rates are random
to capture the variability in the cascade outputs. We also show that cascades
can be rearranged so that blocks with similar rates can be lumped and
represented through our nonlinear modules. Our results can be used both to
represent cascades in computational models of differential equations and to fit
data efficiently, by reducing the number of equations and parameters involved.
In particular, the length of the cascade appears as a real-valued parameter and
can thus be fitted in the same manner as Hill coefficients. Finally, we show
how the obtained nonlinear modules can be used instead of delay differential
equations to model delays in signal transduction.Comment: 18 pages, 7 figure
Correlation between the surface chemistry and the atmospheric corrosion of AZ31, AZ80 and AZ91D magnesium alloys
X-ray photoelectron spectroscopy (XPS) was used in order to investigate the correlation between the surface chemistry and the atmospheric corrosion of AZ31, AZ80 and AZ91D magnesium alloys exposed to 98% relative humidity at 50 °C. Commercially pure magnesium, used as the reference material, revealed MgO, Mg(OH)2 and tracers of magnesium carbonate in the air-formed film. For the AZ80 and AZ91D alloys, the amount of magnesium carbonate formed on the surface reached similar values to those of MgO and Mg(OH)2. A linear relation between the amount of magnesium carbonate formed on the surface and the subsequent corrosion behaviour in the humid environment was found. The AZ80 alloy revealed the highest amount of magnesium carbonate in the air-formed film and the highest atmospheric corrosion resistance, even higher than the AZ91D alloy, indicating that aluminium distribution in the alloy microstructure influenced the amount of magnesium carbonate formedThanks to the MCYT for the financial support given to this work (Project MAT2006-13179-C02-01-02)Peer reviewe
Comportamiento del infarto agudo del miocardio en el hospital “León Cuervo Rubio”, 2006.
Se realizó un estudio descriptivo retrospectivo a los pacientes con infarto agudo del miocardio ingresados de enero de 2006 a enero de 2007, con el objetivo de describir el comportamiento de estos pacientes, identificar los factores de riesgos, los motivos de ingresos, la incidencia según edad, color de la piel y sexo. El sexo más afectado fue el masculino con 36 casos. La mayor incidencia ocurre entre los 66 y los 74 años. El principal factor de riesgo fue la hipertensión arterial con 21 pacientes. El color de la piel que más predominó fue el color blanco con 47 casos. El principal motivo de ingreso fue el dolor precordial seguido de la taquicardia. Prevaleció el infarto no Q y no ocurrieron complicaciones en la mayoría de los casos. Este estudio constituye un pilar vital en las futuras tomas de decisiones para la creación de una Unidad de Cuidados Intensivos Coronarios (UCIC) en hospital donde se realizó la investigación
Multimorbidity clusters in patients with chronic obstructive airway diseases in the EpiChron Cohort
Chronic obstructive airway diseases such as chronic obstructive pulmonary disease (COPD), asthma, rhinitis, and obstructive sleep apnea (OSA) are amongst the most common treatable and preventable chronic conditions with high morbidity burden and mortality risk. We aimed to explore the existence of multimorbidity clusters in patients with such diseases and to estimate their prevalence and impact on mortality. We conducted an observational retrospective study in the EpiChron Cohort (Aragon, Spain), selecting all patients with a diagnosis of allergic rhinitis, asthma, COPD, and/or OSA. The study population was stratified by age (i.e., 15–44, 45–64, and = 65 years) and gender. We performed cluster analysis, including all chronic conditions recorded in primary care electronic health records and hospital discharge reports. More than 75% of the patients had multimorbidity (co-existence of two or more chronic conditions). We identified associations of dermatologic diseases with musculoskeletal disorders and anxiety, cardiometabolic diseases with mental health problems, and substance use disorders with neurologic diseases and neoplasms, amongst others. The number and complexity of the multimorbidity clusters increased with age in both genders. The cluster with the highest likelihood of mortality was identified in men aged 45 to 64 years and included associations between substance use disorder, neurologic conditions, and cancer. Large-scale epidemiological studies like ours could be useful when planning healthcare interventions targeting patients with chronic obstructive airway diseases and multimorbidity
- …