Search results for "Icon"
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Cruces procesionales y cruces de término. Alcance teológico y social de sus particularidades iconográficas
2018
El reino de Valencia, como otros de la Corona de Aragón y del resto de la Península Ibérica, se mostró especialmente propicio al levantamiento de cruces de término; pero los pocos estudios académicos que les han prestado atención se han detenido en su aspecto estilístico, lo que ha llevado a no pocos investigadores a comparar estas cruces con las de orfebrería. Más allá de su decoración, sin embargo, sus respectivas tipologías iconográficas presentan sustanciales diferencias. La ubicación de las cruces de término, fuera del ámbito eclesiástico, su medio material y, sobre todo, su función, podrían haber determinado las diferencias iconográficas respecto a otras cruces y, por ende, las implic…
Mans mnemòniques en l’Ars demonstrativa de Ramon Llull
2014
Aquest article recupera el concepte d’art de la memòria aplicat a les obres de Ramon Llull a partir de la presentació i el comentari de figures de mans amb finalitats mnemotècniques, especulatives i predicadores, que es troben en els manuscrits lul·lians de l’Ars demonstrativa –escrita el 1283– datats del segle xiii i el xvi. En els manuscrits de Venècia (Bibl. Marciana, Lat. VI. 200), de Bèrgam (MA 365) i de San Candido (B. della Collegiata, VIII C.8), la mà està vinculada a la figura S de l’Ars demonstrativa. En el ms &.IV.6 de l’Escorial, en canvi, la mà representa la figura A. El precedent més rellevant d’aquesta iconografia manual és la mà guidoniana, en l’àmbit musical, juntament amb …
Intrapulpal temperature changes during root surface irradiation with an 809-nm GaAlAs laser
2002
The aim of this study was to explore, in vitro, whether the irradiation of human root surfaces with a diode laser might induce nonphysiologic intrapulpal temperature elevations and, therefore, jeopardize pulp vitality.The pulps were removed from human maxillary and mandibular incisors extracted for periodontal reasons. The root canals were enlarged to an apical size #60 file. The teeth were radiographed with standard dental films and a millimeter grid to determine root thickness. The thickness of dentin between the root surface and the pulp in the irradiation areas was 1, 2, and 3 mm. To determine intrapulpal temperature changes during laser irradiation, 0.5-mm K-type thermocouples were ins…
Intrinsic generation of OH groups in dry silicon dioxide upon thermal treatments
2008
We show the existence of an intrinsic generation mechanism of OH groups in synthetic dry silica upon thermal treatments. Samples are treated for ~160 h at 390 °C in He at 2.7 or 180 bar, and the growth of the OH IR absorption band at 3670 cm−1 is observed. An OH concentration of ~10^18 cm^−3 is estimated. Possible contributions of reactions with molecules absorbed from the atmosphere are excluded. Reactions with H2O already contained in the samples are rejected by IR measurements. The observed OH generation is attributed to the reaction of network sites with H2 already present in the material. Possible reaction paths are examined
Photochemical Size Reduction of CdSe and CdSe/ZnS Semiconductor Nanoparticles Assisted by nπ* Aromatic Ketones
2009
A novel effect of n pi* aromatic ketones on the quantum dots optical properties is reported. By controlling experimental conditions such as time of irradiation, presence of air in the media, hydrogen donor capacity of the solvent, and irradiation wavelength, core and core-shell CdSe QDs can be resized as convenient.
Ab initio study of the internal rotation potential of p-disilanylbenzene and p-(1,1′,2,2′-tetramethyldisilanyl)benzene
1996
Abstract We present a detailed ab initio study of the geometrical structure and torsional potential of p -disilanylbenzene and its methyl derivative p -(1,1′,2,2′-tetramethyldisilanyl)benzene. The geometries of the different conformers have been fully optimized at the Hartree-Fock 3-21G ∗ and 6-31G ∗ levels. In all cases, the most stable conformation corresponds to the conformer in which the phenylene group lies in a plane perpendicular to the four silicon atoms. The torsional potential curves calculated using the 3-21G ∗ and 6-31G ∗ basis sets show similar features. In the case of p -(1,1′,2,2′-tetramethyldisilanyl)benzene the interactions between the hydrogen atoms of phenylene and the me…
Rapid Surface Functionalization of Hydrogen-Terminated Silicon by Alkyl Silanols
2017
Surface functionalization of inorganic semiconductor substrates, particularly silicon, has focused attention toward many technologically important applications, involving photovoltaic energy, biosensing and catalysis. For such modification processes, oxide-free (H-terminated) silicon surfaces are highly required, and different chemical approaches have been described in the past decades. However, their reactivity is often poor, requiring long reaction times (2-18 h) or the use of UV light (10-30 min). Here, we report a simple and rapid surface functionalization for H-terminated Si(111) surfaces using alkyl silanols. This catalyst-free surface reaction is fast (15 min at room temperature) and…
Occurrence of currently used pesticides in ambient air of Centre Region (France)
2010
Ambient air samples were collected, from 2006 to 2008 at three rural and two urban sites in Centre Region (France) and analyzed for 56 currently used pesticides (CUPS), of which 41 were detected. The four CUPs most frequently detected were the herbicides trifluralin, acetochlor and pendimethalin and the fungicide chlorothalonil, which were found with frequencies ranging between 52 and 78%, and with average concentrations of 1.93, 1.32, 1.84 and 12.15 ng m(-3), respectively. Among the detected pesticides, concentrations of eight fungicides (spiroxamine, fenpropimorph, cyprodinil, tolyfluanid, epoxiconazole, vinchlozolin, fluazinam, fludioxinil), two insecticides (propargite, ethoprophos), an…
Improved Hölder regularity for strongly elliptic PDEs
2019
We establish surprising improved Schauder regularity properties for solutions to the Leray-Lions divergence type equation in the plane. The results are achieved by studying the nonlinear Beltrami equation and making use of special new relations between these two equations. In particular, we show that solutions to an autonomous Beltrami equation enjoy a quantitative improved degree of H\"older regularity, higher than what is given by the classical exponent $1/K$.
LA CRESCITA EDUCATIVA DELLE NUOVE GENERAZIONI NELL'INCONTRO TRA LE CULTURE
2011
Viene presa in esame l'unica ricerca empirica, condotta sul territorio nazionale, sugli immigrati di seconda generazione. I risultati non sono esaltanti: l'integrazione è problematica, i conflitti si moltiplicano e non sembra facile gestirli. Nel saggio si tenta di dar senso ad una forma di comunicazione interculturale che consenta di accogliere l'altro in modo incondizionato e di comprenderne le idee; si fonda su questo il dialogo autentico e una prospettiva adeguata di educazione interculturale