Use of recycled broken bricks as Partial Replacement Coarse Aggregate for the Manufacturing of Sustainable Concrete

The bricks are one of the primary materials required for construction of homes that no used completely when executes all the walls due, the excess purchase, the cutting to be settle, the breaking for their transfer and its fixed dimensions; this situation requires monitoring on work site the order, cleanliness and accidents. A common practice is these bricks and/or waste are included in the clearing construction before being deposited or eliminated in dumps or sanitary landfills, with their early clogging and shortening them to ther design lifespan. An important alternative to reduce this waste, is to recycle them and reuse them as a concrete component material, due to their high absorption percentage that allows them to keep the water inside of them and then use it in the cement hydration process as internal curing of the concrete. In the present investigation, the effect of crushed clay brick as a replacement for coarse aggregate in concrete processing is studied. The results indicate that with 21 % replacement brick, the plastic contraction decreases, and the compressive strength and flexural strength increase

Electrical properties of individual tin oxide nanowires contacted to platinum electrodes

A simple and useful experimental alternative to field-effect transistors for measuring electrical properties free electron concentration nd, electrical mobility , and conductivity in individual nanowires has been developed. A combined model involving thermionic emission and tunneling through interface states is proposed to describe the electrical conduction through the platinum-nanowire contacts, fabricated by focused ion beam techniques. Current-voltage I-V plots of single nanowires measured in both two- and four-probe configurations revealed high contact resistances and rectifying characteristics. The observed electrical behavior was modeled using an equivalent circuit constituted by a resistance placed between two back-to-back Schottky barriers, arising from the metal-semiconductor-metal M-S-M junctions. Temperature-dependent I-V measurements revealed effective Schottky barrier heights up to BE= 0.4 eV

Validity of water industry wastes in cement industry

This paper examines the validity of several water industry wastes to be reused in different stages of cement production. The wastes considered are: a drinking water treatment plant sludge (DWTP), a sewage sludge (SS) and a spent activated carbon. Different procedures of drying of wastes using a novel dry spray system or subjected to thermal drying or stabilization and dried with lime are analysed. The spray drying process was successfully used with the DWTP sludge (but not with SS). The material was not found to be suitable as a supplementary material in blended cements. Despite this, the spray dried sludge did show good potential as partial or full substitute for clay as a raw material in cement clinker manufacture. A novel thermally drying process (Turbo-drying RINA-JET) was applied to produce dried sewage sludge. The dry sludge consisted of 56 % organic matter and has a high calorific value (8291 J / g), making it valid as an alternative fuel. The ash (35% of dry SS) contains Ca, Fe, P, Si and Al as main inorganic elements which are incorporated into the clinker phases. The burnability of the raw mixture containing this SS sludge was better than in the control raw mix. Furthermore, the paper describes an industrial process for stabilising sewage sludge (SS) with lime and evaluates the viability of the stabilised product, referred to as “Neutral”, as a raw material in the production of Portland cement clinker for the cement industry. The proposed process for sewage sludge treatment has a number of advantages over traditional treatments. In the Basic plant design, the chemical energy in the reagents generates sufficient thermal energy for the moisture to evaporate. This makes the process more energy-efficient than others. The validity of the “Neutral” product as a starting material in raw mixes for the production of cement clinker by substitution of limestone is demonstrated. Regarding the validity of spent activated carbon as an alternative to pet coke as fuel in Portland cement kilns, the carbon differed substantially from the coke, having lower calorific value (18 % less). However, the qualities of the spent coke were still sufficient for the intended use. The ash fraction of the spent activated carbon was mainly composed of anhydrite and quartz (SO3 = 14.1 %) and it is included into the clinker phases during the burning. The SO3 from the ashes promotes a very large growth in alite crystals in the clinker

Modeling Plain Vacuum Drying by Considering a Dynamic Capillary Pressure

A coupled drying model for wood is proposed by introducing a dynamic capillary pressure. The pressures of non-wetting phase, the wetting phase, and the capillary pressure at equilibrium has been considered as non-static; this approach includes a two-scale model. According to numerical results, liquid, water vapor and air dynamics in the chamber have strong interactions with re-homogenization in the surface, controlled by capillary forces. The results at 60–100 bar and 70 °C are discussed. The phenomenological one-dimensional drying model is solved by using the COMSOL’s coefficient form and a global equation format. A good description of drying kinetics, moisture redistribution, and mass fluxes is obtained. A comprehensible transition at the fiber saturation point is well simulated

Evolución costera de la desembocadura del Guadalquivir en los últimos 6000 años (SW de España)

3 páginas, 2 figuras, 5 referencias.Since the last Holocene sea level rise, about 6,900 yr BP, a series of depositional littoral landforms has been generated at the outlet of the Guadalquivir river, with progradation along the predominant longshore drift (towards the east). The littoral spit systems mapped constitute fur progradation phases. The first is dated between the Flandrian maximum (6,900 yr BP) and 4,500 yr BP; the second between 4,200-3,900 yr BP and 2,700-2,600 yr BP; the third between 2,300 yr BP and 1,100 yr BP; and the fourth between 1,000 yr BP and the present. There were separations of successive erosional phases between 4,500-4,200 yr BP, 2,600-2,300 yr BP and, 1,100-1,000 yr BP. Thus, cycles of higher sedimentation are established, with a slight fall and then stability of sea level. Littoral barrier constructions dominate, with the genesis of extensive tidal flats that decrease the size of the estuaries. These sedimentary phases are interrupted by rapid rises in sea level lasting from 100 to 300 years, when the previously constructed littoral barriers are eroded. The cliffs retreat, causing migration inland of dunar constructions, with frequent overlapping layers. Marine influence within the estuaries in creases.Este trabajo ha sido subvencionado por los proyectos coordinados de la DGICYT PB91-0622-C03-0 1 y PB94-1090-C03-0l. Es una contribución al IGCP-367.Peer reviewe

Evaluation of learning outcomes of humanities curricula in medical students. A meta-review of narrative and systematic reviews

Objectives: To assess the expected learning outcomes of medical humanities subjects in medical studies curricula. To connect those expected learning outcomes with the types of knowledge to be acquired in medical education. Methods: Meta-review of systematic and narrative reviews. Cochrane Library, MEDLINE (Pubmed), Embase, CINAHL, and ERIC were searched. In addition, references from all the included studies were revised, and the ISI Web of Science and DARE were searched. Results: A total of 364 articles were identified, of which six were finally included in the review. Learning outcomes describe the acquisition of knowledge and skills to improve the relationship with patients, as well as the incorporation of tools to reduce burnout and promote professionalism. Programs that focus on teaching humanities promote diagnostic observation skills, the ability to cope with uncertainty in clinical practice, and the development of empathetic behaviors. Conclusion: The results of this review show heterogeneity in the teaching of medical humanities, both in terms of content and at the formal level. Humanities learning outcomes are part of the necessary knowledge for good clinical practice. Consequently, the epistemological approach provides a valid argument for including the humanities in medical curricula

Evaluación de la peligrosidad sísmica en España para aplicaciones relacionadas con la seguridad nuclear. Resultados preliminares.

En este trabajo se presentan los avances realizados en el marco del proyecto “Evaluación de la Peligrosidad Sísmica en España para aplicaciones relacionadas con la seguridad nuclear” financiado por el Consejo de Seguridad Nuclear. La finalidad última del proyecto es ahondar en el conocimiento de la peligrosidad sísmica y de su incertidumbre en los emplazamientos de instalaciones críticas como instalaciones nucleares y almacenamientos de residuos radiactivos en nuestro país. Con ese propósito, una primera fase del proyecto está destinada a recopilar y estructurar toda la información generada en proyectos previos financiados por el CSN (DAÑOS, SIGMA, PRIOR, EXPEL y DATACIÓN) concerniente a estudio de fallas activas, análisis de paleosismicidad, catálogos sísmicos y de movimiento fuerte del suelo, etc.. Esta información está siendo integrada y unificada en una Base de Datos y en un Sistema de Información Geográfica. Paralelamente, el código informático desarrollado en el proyecto EXPEL está siendo actualizado para desarrollar cálculos de peligrosidad sísmica siguiendo la metodología PSHA de una forma eficiente, incluyendo formulación de un árbol lógico, cuantificación de incertidumbres epistémicas y aleatorias, análisis de sensibilidad de diferentes opciones en los resultados y desagregación. Los resultados preliminares del proyecto son presentados en esta comunicación, dando una orientación hacia futuros desarrollos y toma de decisiones relacionados con la seguridad nuclear