The surface chemistry of nanocrystalline MgO catalysts for FAME production:an in situ XPS study of H2O, CH3OH and CH3OAc adsorption

An in situ XPS study of water, methanol and methyl acetate adsorption over as-synthesised and calcined MgO nanocatalysts is reported with a view to gaining insight into the surface adsorption of key components relevant to fatty acid methyl esters (biodiesel) production during the transesterification of triglycerides with methanol. High temperature calcined NanoMgO-700 adsorbed all three species more readily than the parent material due to the higher density of electron-rich (111) and (110) facets exposed over the larger crystallites. Water and methanol chemisorb over the NanoMgO-700 through the conversion of surface O2 − sites to OH− and coincident creation of Mg-OH or Mg-OCH3 moieties respectively. A model is proposed in which the dissociative chemisorption of methanol occurs preferentially over defect and edge sites of NanoMgO-700, with higher methanol coverages resulting in physisorption over weakly basic (100) facets. Methyl acetate undergoes more complex surface chemistry over NanoMgO-700, with C–H dissociation and ester cleavage forming surface hydroxyl and acetate species even at extremely low coverages, indicative of preferential adsorption at defects. Comparison of C 1s spectra with spent catalysts from tributyrin transesterification suggest that ester hydrolysis plays a key factor in the deactivation of MgO catalysts for biodiesel production

Laser Cladding of Ni-WC Layers with Graded WC Content

AbstractCoating techniques using powder as added material can be adapted for the manufacture of composition gradients if a mixing unit is included in the powder feed system. As for the laser cladding technology, FGM can be obtained if mixing parameters are changed along the process. This work deals with the development of NiCrBSi layers with WC graded composition. The purpose is to obtain longitudinal compositional gradients within distances of millimeters along a laser scan. To accomplish this task, the capabilities and time delays in the feeding system are identified and analyzed. Preliminar tests on single cladding beads show results in reasonable agreement with expectations

Gait and Cognition: A Complementary Approach to Understanding Brain Function and the Risk of Falling

Until recently, clinicians and researchers have performed gait assessments and cognitive assessments separately when evaluating older adults, but increasing evidence from clinical practice, epidemiological studies, and clinical trials shows that gait and cognition are interrelated in older adults. Quantifiable alterations in gait in older adults are associated with falls, dementia, and disability. At the same time, emerging evidence indicates that early disturbances in cognitive processes such as attention, executive function, and working memory are associated with slower gait and gait instability during single- and dual-task testing and that these cognitive disturbances assist in the prediction of future mobility loss, falls, and progression to dementia. This article reviews the importance of the interrelationship between gait and cognition in aging and presents evidence that gait assessments can provide a window into the understanding of cognitive function and dysfunction and fall risk in older people in clinical practice. To this end, the benefits of dual-task gait assessments (e.g., walking while performing an attention-demanding task) as a marker of fall risk are summarized. A potential complementary approach for reducing the risk of falls by improving certain aspects of cognition through nonpharmacological and pharmacological treatments is also presented. Untangling the relationship between early gait disturbances and early cognitive changes may be helpful in identifying older adults at risk of experiencing mobility decline, falls, and progression to dementia. J Am Geriatr Soc 60: 2127-2136, 2012

Arqueología medieval en el Valle de Orduña (Bizkaia) : Origen y evolución del monasterio de San Clemente de Arbileta

El estudio efectuado en San Clemente de Arbileta destaca por el procedimiento metodológico empleado. Una metodología que engloba el estudio integral del conjunto arqueológico y que considera el edificio como un yacimiento arqueológico único donde aplicar las mismas herramientas estratégicas. Todo ello ha permitido obtener uan extensa secuencia histórico-constructiva que, iniciada en época altomedieval, se dilata hasta practicamente nuestros días, constituyendo una nueva e importante aportación al conocimiento de la génesis y evolución del poblamiento en el valle de Orduñ

Angiographic characterization and clinical implications of specific anatomical features in human coronary arteries

The aim of this dissertation was to provide new insights into the role of invasive coronary angiography in risk stratification for patients with myocardial infarction in specific clinical scenarios.Chapter 2 assessed the occurrence of occlusion of the atrial coronary artery in myocardial infarction patients undergoing emergency angioplasty and its impact on the occurrence of atrial arrhythmias. Chapter 3 focused on the impact of reduced coronary blood flow in the most developed atrial coronary branch and its potential role in the development of atrial arrhythmias in patients with myocardial infarction. Chapter 4 evaluated the effects of atrial ischemia in the left atrium due to reduced coronary blood flow in the dominant atrial coronary branch using advanced echocardiographic techniques. Our results showed that these patients had unfavorable anatomical and functional consequences.Chapter 5 focused on patients presenting with acute coronary syndromes with coronary artery ectasia, which occurred in 4% of patients and was independently associated with an increased risk of severe cardiovascular events. Finally, in Chapter 6, we evaluated the angiographic and clinical profile of patients with COVID-19 who were referred for invasive coronary angiography during the first wave of the outbreak. We found that the most common indication was acute myocardial infarction, often due to high thrombus load. The incidence of severe events in the first month was high.Overall, this dissertation provides important insights into the role of invasive coronary angiography in risk stratification for patients with myocardial infarction in specific clinical scenarios and highlights the potential consequences of reduced coronary blood flow in the development of atrial arrhythmias and unfavorable anatomical and functional consequences in patients with myocardial infarction.Dutch Heart FoundationLUMC / Geneeskund

Intercalary membrane as the inner wall overlying optic and chorio-retinal colobomas. Deep penetration Swept Source-OCT study.

Five eyes of four patients were studied to analyze the structure of the inner wall of optic and chorioretinal colobomas using swept-source optical coherence tomography (SS-OCT). The colobomatous cavities and their relationship with adjacent structures were examined. SS-OCT permitted the study of the colobomatous cavities in all cases. In four of those cases, a Y-shaped intercalary membrane (ICM) was identified, with an origin in the retinal nerve fiber layer (RNFL), which covered the coloboma and in one case the coloboma was in contact with the vitreous cavity. Vitreous adhesion to the internal wall of the coloboma was found in three cases. No clinical or tomographic maculopathy was observed in any patient. High-resolution deep penetration SS-OCT allows in vivo study of optic and chorioretinal colobomas, identifying the RNFL as the main component of the ICM overlying the colobomatous cavities

Ciudad, camino y señas de identidad. La dimensión cultural del camino de Santiago como valor a conservar

El Camino y la ciudad de Santiago de Compostela son patrimonio de la humanidad. Esta condición las convierte en verdaderos símbolos y referentes de nuestras señas de identidad. Dichas señas se mantienen vivas gracias a su fuerte vinculación cultural con objetos, liturgias, ideas e individuos.The Way and the city of Santiago of Compostela are heritage. This condition converts them in true symbols and referents of our signals of identity. This signals maintain alive thanks to his strong cultural links with objects, liturgies, ideas and people

Heat transfer with phase change in a shell and tube latent heat storage unit

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.Concerning thermal energy storage, latent heat thermal energy storage is particularly attractive technique because it provides a high energy storage density. The development of a latent heat thermal energy storage system therefore involves first the understanding of heat transfer in the phase change materials (PCM) when they undergo solid-to-liquid phase transition in the required operating temperature range, and second, the design of the container for holding the PCM and the formulation of the phase change problem. The paper presents a study on the heat transfer mode of a PCM stored in a horizontal cylindrical shell and tube heat exchanger, being the PCM placed inside the tubes. For this purpose, an experimental bench has been developed to test the heat transfer process, coupled with a Ground-Source Heat Pump (GSHP), controlled by a computer program developed to manage the coupled GSHP+PCM system. The aim is to compute the heat transfer of the installation during the loading, storage and downloading energy processes. More precisely, the interest is to check experimentally to what extent some common hypothesis used for heat transfer calculations are valid or not. In particular: (i) Comparison between the radial and the axial heat transfer through the wall of the PCM tube; (ii) The temperature distribution of the heat transfer fluid in the central and peripheral locations; (iii) The heat transfer rate between the container and the ambient temperature. Results indicate that density gradients could occur during energy exchange between the heat transfer fluid and the PCM when melting or solidification are taking place, leading to modification of central flow with respect to peripheral flow. Also, the temperature gradients recorded in the axial direction during the change of phase were very small compared with those of that of the radial direction, indicating essentially a two-dimensional heat transfer mode.dc201

Black-Scholes option pricing within Ito and Stratonovich conventions

Options financial instruments designed to protect investors from the stock market randomness. In 1973, Fisher Black, Myron Scholes and Robert Merton proposed a very popular option pricing method using stochastic differential equations within the Ito interpretation. Herein, we derive the Black-Scholes equation for the option price using the Stratonovich calculus along with a comprehensive review, aimed to physicists, of the classical option pricing method based on the Ito calculus. We show, as can be expected, that the Black-Scholes equation is independent of the interpretation chosen. We nonetheless point out the many subtleties underlying Black-Scholes option pricing method.Comment: 14 page