Compuestos de coordinación derivados de 4,5-dimercapto-1, 3-ditiol-2-tiona 4,5-dimercapto-1,3-ditiol-2-ona y [delta] 2,2'-bis (5-ceto-1,3,4,6-tetratiapentaleno: estudio de su conductividad eléctrica

[spa] El objetivo de esta Tesis es la síntesis, caracterización y estudio de polímeros mono- y bidimensionales de alta conductividad eléctrica derivados de bis(ditiolato)metalatos o tetratiolatos. Para ello se han escogido ligandos sulfurados con alto número de átomos de S que permitan interaccciones fuertes entre ellos. Por otra parte, para una mejor comprensión de la relación conductividad- estructura también se ha procedido al estudio de diversos compuestos mono o dinucleares discretos, obtenidos con tales ligandos. Finalmente, se ha iniciado el estudio de compuestos mixtos planares con un ditiolato y un ligando aminado plano, habiéndose escogido para tal estudio el ligando nitrogenado 2,2'-bipiridilo. En todos los casos se ha procedido al estudio con los cationes Ni(II), Pd(II),Pt(II) , Au(III) y Cu(II) de gran tendencia a la coordinación planocuadrada

Percepción de la creatividad de los docentes de una unidad educativa Guayaquil, 2019

La exploración autorizada "Percepción de la creatividad de los docentes entre los estudiantes de una Unidad educativa, Guayaquil, 2019, indica la teoría de la creatividad según Gardner (inteligencias Múltiples). La cual explica “La creatividad no es una variedad fácil que logre germinar en cualquier trayectoria. María Teresa Esquivias Serrano, 2004, manifiesta, la persona creativa resuelve problemas formales, procesa bienes o revela nuevos temas, de modo que sea apreciada, pero termine en evidencia formativa concreta. Se mide por dimensiones: Creatividad visomotora: Capacidad del alumno para dibujar. Creatividad verbal: Capacidad del estudiante para escribir una historia bien estructurada. Creatividad aplicada: Capacidad del alumno para seleccionar y utilizar los objetos propuestos. La población estaba compuesta por 46 docentes y el ejemplo de 18 educativos se nombró utilizando un modelo no probabilístico, Es un ejemplo de investigación, fundamental, descriptiva, cuantitativa y transversal. El diseño no es experimental, La práctica de la búsqueda se desarrolló y la herramienta utilizada fue el cuestionario de 60 ítems cuyas respuestas están en la escala del pedido, el grado de confiabilidad está entre 0.842 y la validez del contenido se evidencia en el intento de admisión de tres expertos. El procesamiento de la información se ha realizado utilizando el software SPSS versión 24. Los resultados descriptivos de la Tabla 3 mencionan que el 72% de los educativos evalúan en el nivel habitual El nivel de percepción, comprobándose al estudio de la investigación. El estudio concluye que los educativos observan como frecuente la percepción de la creatividad en los docentes del Establecimiento educativo Dr. Francisco Arízaga Luque, durante el año 2019

Four New Trinuclear {Cu3(μ3-OH)(oximate)3}2+ Clusters: Crystal Structure and Magnetic Behavior

Four new triangular copper(II) complexes with the fragment {Cu3(μ3-OH)(oximate)3}2+ and formulae [Cu3(μ3-OH)(μ-Cl)(Py2CNO)3(tBuPO3H)]·4H2O (1), [Cu3(μ3-OH)(μ-Br)(Py2CNO)3(tBuPO3H)]·3.5H2O (2), [Cu3(μ3-OH)(μ-Br)(PhPyCNO)3(tBuPO3H)(MeOH)]·1.5 MeOH (3), [Cu3(μ3-OH)Cl2(PhPyCNO)3]·0.5H2O (4), (Py2CNO = di(2-pyridyl)ketoximate, PhPyCNO = phenyl(2-pyridyl)ketoximate, tBuPO3H2 = tert-butylphosphonic acid) are reported. The magnetic properties of compounds 1-4 were studied. The compounds were found to exhibit strong antiferromagnetic coupling and antisymmetric exchange interaction

Cooperatives and sustainability drivers in the Spanish wine sector. What differences do we find with investor owner firms?

The fight against climate change has become a basic vector for agri-food business strategies. In Spain, commercial wineries (Investor Owner Firms, IOFs) and cooperatives are facing major challenges in adapting to the most stringent environmental requirements and in becoming sustainable and environmentally responsible companies. The European winemaking model, unlike its “new world” competitors, has a very distinct configuration with the predominance of the social economy in parallel with capitalist enterprises. However, these two forms of business organization are different in terms of objectives, position in the value chain, type of organization and form of management. The purpose of this paper is to determine whether these two types of companies have a different orientation towards sustainability, and which are the drivers that facilitate a greater approach to sustainability in each group. With a sample of 411 wineries, the results of the study show a lower orientation towards sustainability among the cooperatives, without a relevant alignment of their resources towards this objective. However, IOFs orient their resources towards sustainability in a consistent and strategic way. This may infer that the European model, with a clear advantage in the social component, could be somewhat more limited in the environmental aspect

Optimized ultrasonic attenuation measures for non-homogeneous materials

In this paper the study of frequency-dependent ultrasonic attenuation in strongly heterogeneous materials is addressed. To determine the attenuation accurately over a wide frequency range, it is necessary to have suitable excitation techniques. Three kinds of transmitted signals have been analysed, grouped according to their bandwidth: narrowband and broadband signals. The mathematical formulation has revealed the relation between the distribution of energy in their spectra and their immunity to noise. Sinusoidal and burst signals have higher signal-to-noise ratios (SNRs) but need many measurements to cover their frequency range. However, linear swept-frequency signals (chirp) improve the effective bandwidth covering a wide frequency range with a single measurement and equivalent accuracy, at the expense of a lower SNR. In the case of highly attenuating materials, it is proposed to use different configurations of chirp signals, enabling injecting more energy, and therefore, improving the sensitivity of the technique without a high time cost. Thus, if the attenuation of the material and the sensitivity of the measuring equipment allows the use of broadband signals, the combination of this kind of signal and suitable signal processing results in an optimal estimate of frequency-dependent attenuation with a minimum measurement time.This work has been supported by the Spanish Administration under grant BIA2014-55311-C2-2-P.Genovés Gómez, V.; Gosálbez Castillo, J.; Carrión García, A.; Miralles Ricós, R.; Paya Bernabeu, JJ. (2016). Optimized ultrasonic attenuation measures for non-homogeneous materials. Ultrasonics. 65:345-352. https://doi.org/10.1016/j.ultras.2015.09.007S3453526

Field-Induced SMM and Visible/NIR-Luminescence Behaviour of Dinuclear LnIII Complexes with 2-Fluorobenzoate

The reaction of Ln(NO3)2·6H2O salts (Ln = Nd, Eu, Gd, Tb, Dy, Er and Yb) with 2-fluorobenzoic acid (H-2-FBz) and 1,10-phenanthroline (phen) in ethanol/water mixture allows the isolation of dinuclear compounds of the formula [Ln2(2-FBz)4- (NO3)2(phen)2] {Ln = Nd (1), Eu (2), Gd (3), Tb (4), Dy (5), Er (6)} and [Yb2(2-FBz)6(phen)2] (7). The solid-state photoluminescence study of the complexes shows the 4f-4f lanthanide transitions in the visible range, in the cases of 2, 4 and 5, and in the NIR range for 1, 6 and 7. Magnetic studies reveal field-induced single-molecule-magnet (SMM) behaviour for compounds 1, 5, 6 and 7

Structural Characterization, Magnetic and Luminescent Properties of Praseodymium(III)‐4,4,4‐Trifluoro‐1‐(2‐Naphthyl)Butane‐1,3‐Dionato(1‐)Complexes

Four new Pr(III) mononuclear complexes of formula [Pr(ntfa)3(MeOH)2] (1), [Pr(ntfa)3(bipy)2] (2), [Pr(ntfa)3(4,4′-Mt2bipy)] (3) and [Pr(ntfa)3(5,5′-Me2bipy)] (4), where ntfa = 4,4,4-trifuoro-1-(naphthalen-2-yl)butane-1,3-dionato(1-), 5,5′-Me2bipy = 5,5′-dimethyl-2,2′-dipyridine, 4,4′-Mt2bipy = 4,4′-dimethoxy-2,2′-dipyridine, have been synthesized and structurally characterized. The complexes display the coordination numbers 8 for 1, 3 and 4, and 10 for 2. Magnetic measurements of complexes 1-4 were consistent with a magnetically uncoupled Pr3+ ion in the 3H4 ground state. The solid state luminescence studies showed that the ancillary chelating bipyridyl ligands in the 2-4 complexes greatly enhance the luminescence emission in the visible and NIR regions through efficient energy transfer from the ligands to the central Pr3+ ion; behaving as "antenna" ligands

Field-Induced SMM and Vis/NIR Luminescence on mononuclear lanthanide complexes with 9-Anthracenecarboxylate and 2,2':6,2'-Terpyridine.

Five new mononuclear lanthanide complexes are synthesized by adding the several lanthanide nitrate hexahydrate salts, which for lanthanide (Ln) are Eu, Tb, Dy, Er, and Yb, with 9-anthracenecarboxylic acid (9-Hanthc) and 2,20 :6,200-terpyridine (TPY) in mixed solution of methanol and dimethylformamide (DMF). The general formula is [Eu(9-anthc)3 (TPY)(DMF)]·H2O (1Eu) where Eu(III) is ennea-coordinated or [Ln(9-anthc)3 (TPY)(H2O)]·H2O·DMF (Ln = Tb (2Tb), Dy (3Dy), Er (4Er), and Yb (5Yb)) where Ln(III) is octa-coordinated. For compounds 3Dy, 4Er, and 5Yb, the dynamic ac magnetic study indicated field-induced single molecule magnet (SMM) behavior. The photoluminescence studies in the solid state of these complexes show the sensitization of 4f-4f transitions for 4Er and 5Yb in the NIR region

A Ferromagnetic Salicylaldoximate/Azide MnII2MnIII6 Cluster with an S = 17 Ground State and a Single-Molecule-Magnet Response

One new MnII 2MnIII 6 cluster exhibiting an S = 17 spin ground state and single-molecule-magnet properties has been designed linking MnIII 3-salicylaldoximate triangles and tetracoordinated MnII cations by means of end-on azido bridges. The ferromagnetic coupling has been rationalized as a function of their structural parameters

Magnetic and Luminescence Properties of 8-Coordinated Pyridyl Adducts of Samarium(III) Complexes Containing 4,4,4-Trifluoro-1-(naphthalen-2-yl)-1,3-butanedionate

A novel series of polypyridyl adducts, [Sm(ntfa)3(NN)] (2-4), with ntfa = 4,4,4-trifluoro-1-(naphthalen-2-yl)-1,3-butanedionate, NN = 2,2′-bipyridine (bipy), 4,4′-dimethyl-2,2′-bipyridine (4,4′-Me2bipy), and 5,5′-dimethyl-2,2′-bipyridine (5,5′-Me2bipy) were synthesized from the precursor complex [Sm(ntfa)3(MeOH)2] (1) and the corresponding pyridyl ligands. Single X-ray crystallography showed that the complexes displayed 8-coordinated geometry. The solid pyridyl adducts 2-4 exhibited emission of luminescence in the NIR and visible regions with close quantum yields (QY = 0.20-0.25%). The magnetic data of 1-4 showed larger values than those expected for magnetically noncoupled Sm(III) complexes in the 6H5/2 ground state, with no saturation on the applied high magnetic field static at a temperature of 2 K