Influence of the molecular interaction in the value of molecular volume for the isotropicnematic transition of p-azoxianisol using th emodel HERSW in conjuntion with IPCM model

In this work, we analyzed the experimental pressure-temperature behavior in the Isotropic-Nematic phase transitionfor the liquid crystal p-azoxianisol at 1 atm using a development for the HERSW Conveg Peg model. Additionally, we obtained the values of the molecular volumes for the hard and attractive cores from theoretical quantum calculations at PM3, PM6 and B3LYP/6-311++G levels considering the molecular interaction among the liquidcrystals (PAA)5. We found that the best prediction for experimental data appears when the effect of the molecular interaction is considered in the volume calculation. Specifically for a/b=3.7, V0=70.86 A3 and a/bl=1.95 the best prediction was obtained

Ecología y etnobotánica dos plantas comestibles de la comunidad Altoandina de Kcana Janansaya, distrito Kunturkanki, Provincia Canas, Cusco

El presente trabajo de investigación se realizó en la comunidad altoandina de Kcana Janansaya, distrito Kunturkanki, Provincia Canas, Región Cusco, a 4 085 m de altitud, desde febrero a abril de año 2013; con el objetivo de estudiar dos especies de plantas comestibles de la comunidad mencionada. El método empleado fue el Muestreo Aleatorio Simple (MAS) al azar. El área de la muestra es de 0.135 ha (1 350 m2) distribuidos en9 parcelas rectangulares de 150 m2(10 x 15 m), las que a su vez se dividieron en subparcelas de 1 m2 (1 x 1 m). Se registró 783 especímenes, de los cuales, la especie Stangea rhizantha (A. gray) Killip predomina con 50.83 % (398 muestras), en comparación con la especie Hypochaeris taraxacoides (Walpers) Bentham & Hooker f. que posee el 49.16 % (385 muestras). De las cualidades nutricionales; la segunda especie resalta en carbohidrato con 18.0 %, fósforo 83.0 mg/100 y potasio 14.0 mg/100. De las 69 personas encuestadas, el 56.52 % (21 varones, 18 mujeres) informan que ambas especies se consumen crudo, el 36.23 % (15 varones, 10 mujeres) indican que se expenden en los mercados comunales y distritales, el 7.24 % (4 varones, 1 mujer) no saben ni opinan

Systematic Study of the Multiple Variables Involved in V₂AlC Acid-Based Etching Processes, a Key Step in MXene Synthesis

The realization of the broad range of application of MXenes relies on the successful and reproducible synthesis of quality materials of tailored properties. To date, most MXenes have been produced making use of acid-based etching methods, yet an in-depth understanding of etching processes is lacking. Herein, we have engaged in a comprehensive study of the multiple variables involved in the synthesis of V2CTx with focus on the properties of etched materials. Two main sets of experiments were considered, each using a different V2AlC precursor and a range of synthesis variables including reaction time and temperature, mixing rate, and type of acid. Correlations of synthesis conditions–materials properties were investigated using a broad range of characterization techniques including analytical methods, scanning and transmission electron microscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Findings indicated the crucial relevance of properties of the MAX precursor such as elemental composition, particle size, and crystal structure on etching processes and properties of etched materials. Particularly, depending on the MAX precursor, two etching patterns were identified, core–shell and plate-by-plate, the latter describing a more efficient etching. Combined studies of elemental composition, crystal structure, and yield quantification allowed us to evaluate the effectiveness of etching processes. XRD studies revealed key crystal-structure-type of acid correlations showing advantages of using a HF/HCl mix over only HF. Analytical methods XRD and XPS delivered insights into undergoing chemical processes and their influence on bulk and surface chemistry of etched materials. The relevance for reaction kinetics of highly correlated variables such as reaction vessel dimensions, mixing efficiency, and reaction temperature was recognized. For the first time, a MXene synthesis has been investigated comprehensively highlighting its multivariable nature and the high variable intercorrelation, opening up venues for further investigation on MAX and MXene synthesis

Study of metals in leached soils of a municipal dumpsite in Tampico, Tamaulipas, Mexico: preliminary results

The Zapote dumpsite measures 420000 m 2 and is 28 years old; an estimated 2.5 millions tons of waste have accumulated on the site (household waste, clinical waste, commercial waste). The thickness of the waste is 3 to 9 meters. Since operations began, no control regulations have existed on the residues received. The Zapote dumpsite is located within a salt-marsh between a system of channels and river lagoons of brackish water, located in a tropical sedimentary environment in the urban zone of Tampico, Tamaulipas, Mexico. Recently, the Zapote has been closed and work is presently underway in its rehabilitation since a geo-environmental perspective. The present investigation integrates information of preliminary results of metals (Pb, Ni, Cd, Cu, Mg, Fe and Al) contained in sediments that underlie the Zapote dumpsite. In laboratory research the metals of the sediment were correlated with the metals contained in samples of leachate from the Zapote dumpsite. The concentration of metals Pb, Ni, Cd, Cu, Mg, Fe and Al were analyzed in samples of sediments that underlie the body of the dumpsite in layers of 10 cm, reaching a depth of 1.5 m under the interface waste-soil. The results denote high concentrations of metals in layers that are in contact with waste that decreased until reaching 60 to 80 cm of depth. The proportions of the concentrations of metals studied in the soil are comparable with that leached, until layers of 60 to 80 cm of depth are reached, and are then lost in the deepest layers. The high plastic characteristics of clay layers have stood in the way of metallic contaminants in sub layers of the Zapote dumpsite. The results were correlated with metal concentrations of natural and anthropogenic sediments of the region

Determinantes del resultado de la innovación en empresas españolas

Se ha comprobado que la innovación es fundamental para la supervivencia de las empresas al igual que para el crecimiento de un país, por tal motivo una eficiente inversión en innovación permitirá obtener resultados óptimos y a su vez conseguir mejoras en la organización de la empresa, eficiencia en la gestión y sobre todo obtener ventajas competitivas que generen una consolidación en el mercado. En el presente estudio se examina cómo determinantes de la innovación, en específico: La innovación de productos, la innovación de procesos y las patentes, influyen en el resultado de la innovación en empresas manufactureras españolas; considerando el efecto que ejercen los outputs de innovación a partir de los inputs de innovación (gastos internos de I+D, gastos externos de I+D, financiación pública, personal especializado en I+D y cooperación con agentes externos) durante el período 2003-2016. Este análisis empírico utiliza una muestra de 12.849 empresas que ejecutan actividad innovadora en territorio español, por medio de la base de datos PITEC. Los principales resultados obtenidos reflejan que todos los indicadores analizados favorecen el proceso innovador de las empresas, admitiendo como conclusión, una relación causal entre los esfuerzos aplicados en innovación y la capacidad de respuesta de las empresas

Intensive Habitat Loss in South Spain: Arborescent Scrubs with <em>Ziziphus</em> (5220*)

The habitat arborescent matorral with Ziziphus (5220*) was included in the Habitats Directive of the European Commission. These plant formations represent the maximum potential vegetation in a very restrictive arid environment, since it encompasses endemic, tropical, or Maghrebian floristic elements, and from other areas of the ancient Thetis Sea. In fact, the version of this community with Gymnosporia senegalensis (Lam.) Loes. [=Maytenus senegalensis (Lam.) Exell] constitutes extraordinarily singular flora formations in the Iberian southeast. These are unique communities in Europe and ecologically extremely valuable and, however, have been included among the Europe’s most endangered habitats. The vast economic development experienced in South Spain based on the remarkable transformation of traditional farming patterns into a highly profitable agriculture that uses industrial production methods and the groundwater intensively (agriculture intensification and land-use change), in addition to urbanization without sustainable land planning, determines that European G. senegalensis populations are seriously threatened by severe habitat destruction and fragmentation