657 research outputs found

    Meteorización de las granulitas de Cabo Ortegal

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    [Resumen] Se realiza el estudio químico y mineralógico del proceso de alteración, en medios sustractivos, de las granuli tas de Cabo Ortegal, la precipi tación media anual supera los 1.300 mm. y las temperaturas medias mensuales extremas son 23ºC y 4,7ºC. Durante el proceso de meteorizaciór se origina una fuerte pérdida de Ca, Na y Mg y,en menor proporción, de Si con acumulación relativa de Fe y Al. Como productos de alteración aparecen filosilicatos 1:1 dioctaédricos, gibbsita, oxihidróxidos de hierro y micas y cloritas degradadas. La edafogénesis es de tipo fermonosialítico con una tendencia ferralítica, al menos en sus fases iniciales.[Abstract] This paper is a chemical and mineralogical study about the weathering process, in subtr&ctive environments, of the granul i tes in Cabo Ortegal. The mean annual precipitation is over 1.300 mm. and the mean monthly extreme temperatures are 23ºC and 4,7ºC . In the process of weathering there is an intense 10S8 of Ca, Na and Mg and, in a minar level , of Si, with a relative accumulation of Fe and Al. Proqucts of the weathering are 1: 1 dioctahedral phyllosilicates, gibbsi teiron oxyhydroxides and degraded micas and chlorites. The pedogenesis is of fermonosialli tic type wi th a ferrallitic tendence, in the first phases at least

    Characterization and production of shiitake (Lentinula edodes) in Mexico using supplemented sawdust

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    The cultivation of shiitake in Latin America started during the early 1980's, and several attempts for its commercial cultivation have been carried out during the last decade in Guatemala, Colombia, Mexico, Argentina and Brazil. However, a major constrain has been the lack of basic research, allowing further development. In this work, we studied two genotypes of Lentinula edodes (CP-7 and CP-163) selected from 16 strains being used in the region at different levels, in order to assess their mycelial growth rate in Petri dishes, as well as yield (biologic efficiency, production rate) and quality of fruit bodies, using 10 different formulations of supplemented sawdust from a common Mexican oak tree (Quercus acutifolia Neé). The best mycelial development was 8.5 mm/day for the genotype CP-163 cultivated on 70% Quercus sawdust, 10% corn-cobs, 10% maize stubble, 7% wheat bran and 3% rice meal. The highest yield was recorded in the genotype CP-7, using 60% Quercus sawdust, 28.5% corn-cobs, 10% maize stubble, 1.5% gypsum, thiamine (100 mg/kg), and magnesium sulfate (20 g/100 kg); reaching a biologic efficiency of 103%, a production rate of 1.3, and a high proportion (41.8%) of fruit bodies, having good commercial quality (41 to 70 g fresh weight, > 12 cm cap diameter and 96.5% of regular shape). On the basis of this study, this last genotype and formulation was recommended, as well as to establish a breeding program at the molecular level for shiitake production on a large scale in Mexico or other Latin American countries.Keywords: Edible mushrooms, genotypes, substrates, mycelial growth rate, biologic efficienc

    Winter Diet of Montezuma Quail in Arizona and New Mexico

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    Investigating the diet composition of Montezuma quail (Cyrtonyx montezumae) is fundamental for unveiling how food resources limit the species’ population size and may provide relevant tools for their harvest and habitat management. The objective of this research was to determine the composition and geographic variation of the winter diet of the Montezuma quail in Arizona and New Mexico, USA, from quail crops harvested during the hunting seasons of 2008–2017. In addition, we used beta regression analyses to determine the effect of environmental factors and ecological variables (annual mean precipitation, annual mean temperature, landscape diversity, diet diversity, time of hunt, longitude, latitude, and elevation) on Montezuma quail diet composition. We found that acorns (Quercus spp.) and sedge rhizomes (Cyperus fendlerianus) are the most frequent food items of Montezuma quail in Arizona and New Mexico, respectively, followed by tepary beans (Phaseolus acutifolius), woodsorrel tubers (Oxalis spp.) and insects in both states. Individual crop wet mass is positively associated with time of day during winter. Geographic variation in Montezuma quail diet composition in Arizona and New Mexico was associated with mean annual precipitation for acorns and with geographic variation in mean annual temperature for rhizomes and tubers of sedge (Cyperus spp.). Geographic variation of other food items was not associated with those environmental factors. These functional relationships between the species’ diet and environmental factors suggest that Montezuma quail preference towards these two principal food items is subject to climatic control. Therefore, warmer and drier environments in the southwestern United States and northern Mexico may affect the species’ distribution through changes in food availability

    MEXICAN WILD LUPINES AS A SOURCE OF QUINOLIZIDINE ALKALOIDS OF ECONOMIC POTENTIAL

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    Quinolizidine alkaloids such as lupanine,13-hydroxylupanine, multiflorine, angustifoline and sparteine, which are present inthe species of the genus Lupinus, have beenreported to have biopesticide and pharmacological activities. The aim of this studywas to quantify the content and variationof the individual alkaloids in seeds of L.mexicanus, L. exaltatus, L. montanus andL. stipulatus collected in different states ofMexico. Lupanine was the major (5.05 ±0.37 mg/g) alkaloid found in L. mexicanus,whereas sparteine was the main alkaloidpresent in L. montanus (3.97 ± 0.49 mg/g).Conversely, L. stipulatus contained onlysmall quantities of lupanine and sparteine(0.1 ± 0.002 and 0.04 ± 0.01 mg/g, respectively). Angustifoline was detected only in L.montanus, but in a very low amount (0.048± 0.03). The results of this study indicatethat L. mexicanus and L. montanus can beconsidered as important sources of lupanine and sparteine for their use as natural pesticide or pharmacological agents.Los alcaloides quinolizidinicos lupanina,13-hidroxilupanina, multiflorina, angustifolina y esparteina, presentes en el géneroLupinus poseen actividades bioplagiciday farmacológica. El objetivo del presenteestudio fue cuantificar el contenido y variación de los alcaloides mencionados ensemillas de L. mexicanus, L. exaltatus, L.montanus y L. stipulatus, colectados endiferentes estados de México. La lupaninafue el principal (5.05 ± 0.37mg /g) alcaloideencontrado en L. mexicanus, mientras que laesparteína fue el mayor alcaloide presente en L. montanus (3.97 ± 0.49 mg/g). Sinembargo, en L. stipulatus se encontraron pequeñas cantidades de lupanina y esparteína(0.1 ± 0.002 y 0.04 ± 0.01 mg/g, respectivamente). La angustifolina sólo se detectóen bajos niveles en L. montanus (0.048 ±0.03). Los resultados de este estudio indicanque L. mexicanus y L. montanus pueden serconsiderados como una fuente importantede lupanina y esparteína, los cuales puedenser utilizados como pesticidas o hipoglucé-micos naturales

    Implementation of an intraoperative electron radiotherapy in vivo dosimetry program

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    Background: Intraoperative electron radiotherapy (IOERT) is a highly selective radiotherapy technique which aims to treat restricted anatomic volumes during oncological surgery and is now the subject of intense re-evaluation. In vivo dosimetry has been recommended for IOERT and has been identified as a risk-reduction intervention in the context of an IOERT risk analysis. Despite reports of fruitful experiences, information about in vivo dosimetry in intraoperative radiotherapy is somewhat scarce. Therefore, the aim of this paper is to report our experience in developing a program of in vivo dosimetry for IOERT, from both multidisciplinary and practical approaches, in a consistent patient series. We also report several current weaknesses. Methods: Reinforced TN-502RDM-H mobile metal oxide semico nductor field effect tran sistors (MOSFETs) and Gafchromic MD-55-2 films were used as a redundant in vivo treatment verification system with an Elekta Precise fixed linear accelerator for calibrations and tre atments. In vivo dosimetry was performed in 45 patients in cases involving primary tumors or relapses. The m ost frequent primary tumors were breast (37 %) and colorectal (29 %), and local recurrences among relapses was 83 %. We made 50 attempts to measure with MOSFETs and 48 attempts to measure with films in th e treatment zones. The surgical team placed both detectors with supervision from the radiation oncologist and following their instructions. Results: The program was considered an overall success by the different professionals involved. The absorbed doses measured with MOSFETs and films were 93.8 ± 6.7 % and 97.9 ± 9.0 % (mean ± SD ) respectively using a scale in which 90 % is the prescribed dose and 100 % is the maximum absorbed dose delivered by the beam. However, in 10 % of cases we experienced dosimetric problems due to detector misalignment, a situation which might be avoided with additional checks. The useful MOSFET lifetime length and the film sterilization procedure should also be controlled. Conclusions: It is feasible to establish an in vivo dosimetry program for a wide set of locations treated with IOERT using a multidisciplinary approach according to the skills of the professionals present and the detectors used; oncological surgeons ’ commitment is key to success in this context. Films are more unstable and show higher uncertainty than MOSFETs but are cheaper and are useful and convenient if real-time treatment monitoring is not necessary.This work was supported by grants IPT-300000-2010-3 and PI11/01659 from the Spanish Government and ERDF funds

    Piezoelectric composite cements: Towards the development of self-powered and self-diagnostic materials

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    Piezoresistivity is the most commonly used sensing principle in cement-based smart composites for strainmonitoring applications. Nonetheless, the need for external electric power to conduct electrical resistivity measurements restricts the scalability of this technology, especially when implemented in remote structures. To address this issue, this manuscript thoroughly analyses the piezoelectric properties of cement composites doped with reduced graphene oxide (rGO) and evaluates their potential as self-powered strain sensors. To do so, a comprehensive methodology involving voltammetry measurements, open circuit potential determination, and uniaxial compression testing is developed to determine the piezoelectric coefficients of charge �33 and voltage �33. Furthermore, a novel circuital model for signal processing of the electromechanical response is developed and experimentally validated in terms of time series of output voltage, resistance, and the generated electric power. The developed methodology is applied to laboratory samples manufactured following two different filler dispersion methods. The presented results evidence that samples prepared by ultrasonic cleaner dispersion achieve optimal properties, with a piezoelectric charge coefficient of 1122.28 ± 246.67 pC/N, about 47 times greater than previously reported composites in the literature. Unlike piezoresistive cement-based composites, a remarkable nonlinear correlation between the fractional change in the intrinsic resistance of the material and the applied mechanical strain has been observed. Instead, a considerable linearity (R 2 = 0.96) between the externally applied mechanical strain and the generated (piezoelectric) electric power has been found, which suggests the great potential of the latter for conducting off-the-grid strain monitoring applications

    Comparación del desempeño de jóvenes en pruebas neuropsicológicas en formato lápiz y papel e informatizadas

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    Los campos de la aplicación de pruebas psicológicas y neuropsicológicas se han visto impactos por la tecnología específicamente con las pruebas informatizados. Una de las preguntas frecuentes en versiones papel y lápiz comparadas con una versión informatizada de la misma prueba, es si éstas son equivalentes. El objetivo de este estudio fue comparar el desempeño de pruebas neuropsicológicas en formato lápiz y papel y formato computarizado. Participaron 41 estudiantes en dos aplicaciones de las mismas pruebas en las dos versiones. Se encontró que los desempeños fueron equivalentes en la mayoría de las pruebas. Sin embargo, existen variaciones en las modalidades dependiendo de la ejecución de la prueba y con alta variabilidad entre sujetos. Esto sugiere que la diferencia en las puntuaciones podría deberse a la diferencia en los procesos cognitivos subyacentes a la ejecución de las dos modalidades
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