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

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

Numerical Simulation of Warm-air Drying of Mexican Softwood (Pinus pseudostrobus): An Empirical and Mechanistic Approach

In this work, the numerical simulation of Mexican softwood (Pinus pseudostrobus) drying is presented by solving a phenomenological model. The model was developed by considering the heat and mass balance in the representative elementary volume, which involves the solid, liquid and gas phases. We solved a system of partial differential equations by numerical factorization in COMSOL multiphysics 3.5a©. Three primary variables were solved: the moisture content, the temperature, and the dry-air mass. The numerical results were compared against both experimental data and a semi-empirical model (Characteristic Drying Curve) previously published. The warm-air drying of Mexican softwood was simulated on a one-dimensional basis by considering two experimental conditions: air flow temperature at 60 and 80 ºC. Relative humidity was not controlled in the tunnel dryer. Simulated drying kinetics showed good agreement with the experimental data

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

Richness and Current Status of Gymnosperm Communities in Aguascalientes, Mexico

The gymnosperm diversity of Aguascalientes, Mexico, is presented. Fifteen species from five genera and three families are reported, two of Coniferales (Cupressaceae and Pinaceae) and one of Gnetales (Ephedraceae). Pinus is the most diverse and abundant genus with seven species. The most abundant species is P. teocote, while P. strobiformis is the scarcest. Juniperus is the next most diverse genus, represented by four species, with J. deppeana the most abundant and J. durangensis the scarcest. Cupressus lusitanica, Taxodium mucronatum and Ephedra compacta are each the sole representatives of their genera. Most conifers occupy the mountainous part of the state, forming temperate forest; exceptions are Taxodium, which is located on the margins of permanent streams, and J. coahuilensis, which is found in the low parts of the Aguascalientes Valley over calcareous soils in the northern part of the state. Ephedra is distributed in the northeast part of Aguascalientes in microphyll desert scrub. The current status of the gymnosperm communities in the state of Aguascalientes is discussed

Synthesis of tri- and tetramines containing two 2,3-dihydroxypyrrolidine moieties and their inhibitory activity toward α-mannosidases

Through the reductive amination of N-[(tert-butoxy)carbonyl]-2,5-dideoxy-2, 5-imino-3,4-O-isopropylidene-L-ribose with tetramethylenediamine, hexamethylenediamine, 2,7-diaminofluorene, 4,4′-diaminodiphenylmethane and 1,4-(diaminomethyl)benzene, five tetramines containing two (2R,3R,4S)-2- aminomethylpyrrolidine-3,4-diol moieties have been prepared and assayed for their inhibitory activities toward 24 glycosidases. Tetramines containing the tetramethylene or benzene-1,4-dimethylene linkers are more potent α-mannosidase inhibitors than simple (2R,3R,4S)-2-aminomethylpyrrolidine- 3,4-diols. Triamines such as (2S,3R,4S)-bis(3,4-dihydroxy-pyrrolidin-2-ethyl) amine were also prepared and shown to be better α-mannosidase inhibitors than (2S,3R,4S)-2-(2-aminoethyl)pyrrolidin-3,4-diol

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