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showing 10 items of 3539 documents
El ciclo de la vida de San Ignacio de Loyola pintado por Cristóbal de Villalpando en Tepozotlán. Precisiones iconográficas
1994
LOS PINTORES QUE EN SUS OBRAS REPRESENTARON LA VIDA Y MILAGROS DE SAN IGNACIO DE LOYOLA, PUDIERON INSPIRARSE EN LAS NUMEROSAS ESTAMPAS DE GRABADOS QUE ACOMPAÑARON LA CAMPAÑA DE PROPAGANDA QUE TUVO LUGAR A RAIZ DE SU BEATIFICACION Y POSTERIOR CANONIZACION. ENTRE ELLAS, LA SERIE MAS NUMEROSA Y COMPLETA FUE LA GRABADA POR JEAN BAPTISTA BARBE SEGUN DIBUJOS DE RUBENS, PUBLICADA EN ROMA EN 1609. EN MUCHAS DE ESTAS ESTAMPAS SE BASO CRISTOBAL DE VILLALPANDO PARA REALIZAR LA SERIE SOBRE LA VIDA DEL SANTO EN EL NOVICIADO DE TEPOZOTLAN, MEXICO. LAS PINTURAS, FECHADAS EN 1710, CORRESPONDEN AL ULTIMO PERIODO, EN EL QUE RECURRIO A COLABORADORES, LO QUE EXPLICA LAS DESIGUALDADES DE CALIDAD (ABC/LAG).
A two-component model for the 2260cm−1 infrared absorption band in electron irradiated amorphous SiO2
2011
Abstract We report an experimental study by infrared absorption (IR) measurements focused on the effects of electron irradiation in the dose range from 1.2 × 10 3 kGy to 5 × 10 6 kGy on the intrinsic band peaked at 2260 cm − 1 in amorphous silicon dioxide (a-SiO 2 ) materials. This IR band is particularly relevant as it is assigned to an overtone of the strong asymmetric stretching vibration of Si–O–Si bridges and consequently it is intimately related to the Si–O–Si bond angle distribution. In a recent work we have shown that structural modifications induced by irradiation take place through the nucleation of confined high-defective and densified regions statistically dispersed into the w…
Enhanced light scattering in Si nanostructures produced by pulsed laser irradiation
2013
An innovative method for Si nanostructures (NS) fabrication is proposed, through nanosecond laser irradiation (lambda = 532 nm) of thin Si film (120 nm) on quartz. Varying the laser energy fluences (425-1130 mJ/cm(2)) distinct morphologies of Si NS appear, going from interconnected structures to isolated clusters. Film breaking occurs through a laser-induced dewetting process. Raman scattering is enhanced in all the obtained Si NS, with the largest enhancement in interconnected Si structures, pointing out an increased trapping of light due to multiple scattering. The reported method is fast, scalable and cheap, and can be applied for light management in photovoltaics. (C) 2013 AIP Publishin…
Numerical study and comparisons with experimental data for transient behaviour of phase boundaries during industrial FZ process for silicon crystal g…
2005
Abstract In our numerical transient model developed previously for the industrial FZ crystal growth process with the needle-eye technique, the meshing algorithms are essentially improved and a significant amount of numerical studies are carried out for model verification. Transient modelling for the experimental growth process with step-like time dependences of inductor current and feed rod velocity has shown that time dependencies of the crystal radius and zone height calculated numerically agree with the data from praxis. The fully transient simulation for growth process of crystal starting cone has shown that the model is capable of performing the simulation even if the crystal diameter …
Modulated Crystal Structure and Electronic Properties of Semiconductor Cu47Si91P144
2000
Crystals of the copper silicon phosphide were synthesized by the iodine gas transport technique. The x-ray single crystal methods revealed a big superstructure with the lattice parameters a = b = 44.510 and c = 20.772 A and a basic tetragonal substructure with a = 3.7092 and c = 5.1930 A. Analysis of the intensities showed that the superstructure has a 1/2,1/2,1/2 tetragonal substructure with a = 22.255 and c = 10.386 A. This 1/2,1/2,1/2 substructure (Cu47Si91P144) and the basic tetragonal structure (Cu0.71Si1.29P2) were solved by the direct methods and refined in the I4m2 space group. The phosphide is a semiconductor with a small energy gap of 0.0269(1) eV. The electrical properties are co…
Ion-exchange high-performance liquid chromatography of nucleotides and polypeptides on new types of ion-exchange sorbents, based on polystyrene-coate…
1991
A novel type of ion exchanger was prepared by multipoint covalent binding of polystyrene chains onto the surface of porous silica followed by polymer-analogous modification of the bonded layer. Both anion and cation exchangers were synthesized and examined in the separation of nucleotides and proteins. Rapid and efficient separation of basic polypeptides on strong anion exchangers and that of acidic polypeptides on strong cation exchangers could be achieved. For the separation of complete mixtures of polypeptides the application of zwitter-ionic ion exchangers can be recommended.
An experience of elicited inquiry elucidating the electron transport in semiconductor crystals
2016
In this study we report the results of an inquiry-driven learning path experienced by a sample of 10 electronic engineering students, engaged to investigate the electron transport in semiconductors. The undergraduates were first instructed by following a lecture-based class on condensed matter physics and then involved into an inquiry based path of simulative explorations. The students were invited by two instructors to explore the electron dynamics in a semiconductor bulk by means of Monte Carlo simulations. The students, working in group, had to design their own procedure of exploration, as expected in a traditional guided inquiry. But they experienced several difficulties on planning and…
Bacterial sensors based on biosilica immobilization for label-free OWLS detection
2013
In the last years, a new group of enzymes, the so-called silicateins, have been identified and characterized, which form the axial filaments of the spicules of the siliceous sponges, consisting of not only amorphous silica among others. These enzymes are able to catalyze the polycondensation and deposition of silica at mild conditions. Silicateins can be expressed in Escherichia coli. The recombinant proteins are expressed on the surface of the cell wall and are able to catalyze the formation of a polysilicate net around the bacterial cells providing the possibility for further attachment to the surface of SiO2 containing sensor chips. With this mild immobilization process it is now possibl…
Silica Nanoparticles for Insect Pest Control.
2019
To date, control strategies used against insect pest species are based on synthetic insecticide applications. In addition, the efficacy of these treatments could be decreased due to insecticide resistance in insect populations. Also, the irrational use of chemical control strategies has negative consequences of non-target organisms and threatening human health. Designing nanomaterial for pest insect control is a promising alternative to traditional insecticide formulations. In particular, it has been proven that silica nanoparticles have the potential for molecules delivery, release control improvement and also their toxicity as insecticide alone. In this work, we summarized the state of kn…
Cheap Sensor Made of Multicrystalline Silicon for Insolation and Temperature Measurements
2016
Abstract In the paper some results on measurement of insolation and „real” cell’s temperature carried out with use of standard silicon solar cells are presented. Two identical cells are applied in such a sensor. Short circuit current of one cell is a direct indication of insolation value and open circuit voltage of the other cell is indirect indication of actual sensor’s temperature but in this case more complex formula must be used for temperature calculation.