Search results for "Espectro"
showing 10 items of 142 documents
Snapshots of a solid-state transformation: Coexistence of three phases trapped in one crystal
2016
Crystal-to-crystal transformations have been crucial in the understanding of solid-state processes, since these may be studied in detail by means of single crystal X-ray diffraction (SCXRD) techniques. The description of the mechanisms and potential intermediates of those processes remains very challenging. In fact, solid-state transient states have rarely been observed, at least to a sufficient level of detail. We have investigated the process of guest extrusion from the non-porous molecular material [Fe(bpp)(HL)](ClO)·1.5CHO (bpp = 2,6-bis(pyrazol-3-yl)pyridine; HL = 2,6-bis(5-(2-methoxyphenyl)-pyrazol-3-yl)pyridine; CHO = acetone), which occurs through ordered diffusion of acetone in a c…
Aperiodic Diffract: Study of diffraction gratings
2014
In this work we introduce a virtual laboratory, APERIODIC DIFFRACT, developed in Matlab GUI (Graphical User Interface) as an informatics tool for teaching the diffractive properties of aperiodic gratings. This GUI allows the student to generate aperiodic sequences by iterating and lets to study the spectra for different iterating orders.<br /><br />
Unraveling the strain state of GaN down to single nanowires
2016
International audience; GaN nanowires (NWs) grown by molecular beam epitaxy are usually assumed free of strain in spite of different individual luminescence signatures. To ascertain this usual assumption, the c/a of a GaN NW assembly has been characterized using both X-ray diffraction and Raman spectroscopy, with scaling the measurement down to the single NW. Free-standing single NWs have been observed free of strain-defined as [c/a = (c/a)(o)]/(c/a)(o)-within the experimental accuracy amounting to 1.25 x 10(-4). However, in the general case, a significant portion of the NWs is coalesced, generating an average tensile strain that can be partly released by detaching the NWs from their substr…
La ratio interdigital D2:D4 y su relación con otros indicadores de androgenización en progenitores de personas con trastornos del espectro autista
2013
The 2D:4D ratio is the quotient between the index and ring finger lengths and is a non-direct indicator of androgenisation. If prenatal testosterone levels in the amniotic fluid are high then the probability increases of developing lower ratio values. It has been suggested that people with autism spectrum disorders (ASD) and their parents may have highly androgenised brains, and for this reason the 2D:4D ratio is used as a marker of such idiosyncrasies. This study aims to analyse if parents of people with ASD differ from the general population in several parameters of androgenisation related to the 2D:4D ratio. The sample was composed of 43 parents of offspring with ASD and 42 controls who …
Análisis de psicoactivos en aguas, sedimentos y alimentos: de la epidemiología de alcantarilla a la forensía medioambiental
2017
Las drogas de abuso tanto lícitas como ilícitas, los fármacos y los productos de higiene personal son contaminantes emergentes cuyo impacto para los ecosistemas es todavía escasamente conocido. En las últimas décadas ha habido un creciente interés en el estudio de estas sustancias debido a su elevado consumo y continua descarga en compartimentos medioambientales, tras su insuficiente eliminación en las estaciones depuradoras de aguas residuales (WWTPs). La naturaleza y cantidad de estos contaminantes están frecuentemente relacionados con las características, estado de salud y hábitos de las poblaciones que vierten a estas WWTPs. Por todo ello, el estudio de estos contaminantes tiene una dob…
Aperiodic Diffract: Study of diffraction gratings
2014
[EN] In this work we introduce a virtual laboratory, APERIODIC DIFFRACT, developed in Matlab GUI (Graphical User Interface) as an informatics tool for teaching the diffractive properties of aperiodic gratings. This GUI allows the student to generate aperiodic sequences by iterating and lets to study the spectra for different iterating orders.
Espectros de Hegel en la archipolítica heideggeriana
2008
Rocio.Garces@uv.es A partir de una distinción interna a la lógica especulativa entre lógica espiritual y lógica espectral, este texto busca las huellas de los espectros de Hegel en la archipolítica heideggeriana. El hilo conductor es la posición de Kierkegaard frente a la dialéctica hegeliana para mostrar cómo la ontología de Heidegger depende de la comprensión kierkegaardiana del vínculo social en términos de nivelación y abstracción; del “fantasma del público” y del “espectro de la pura interioridad”. De tal modo que la presencia oculta de algunos espectros del hegelianismo en la obra de Heidegger va a condicionar su comprensión de la comunidad, sobre todo en lo que respecta a las atadura…
Control de micotoxines en cereals i derivats per cromatografia liquida espectrometria de masses : avaluació de les ingestes
2012
Mycotoxins are secondary metabolites produced by few fungal species that readily colonize crops and contaminate them with toxins in the field or after harvest. Surveillance studies have showed that mycotoxin contamination is a world-wide problem, since it is estimated that 25% of the world's crop production and 20% of crop production within the European Union may be contaminated with these contaminants. Economic losses deriving from that are tremendous, including reduction of livestock production and agricultural production, health care, veterinary and regulatory costs. The methods described in this Thesis for the extraction of mycotoxins from cereal and derivates used conventional techniqu…
nuevos desafíos en espectroscopia vibracional
2017
El principal objetivo de la Química Analítica Verde es la sustitución de metodologías contaminantes por otras más limpias, mediante: La reducción de reactivos y disolventes empleados en el pre-tratamiento y análisis de las muestras. Minimizar las cantidades y de la toxicidad de los compuestos empleados en las etapas de preparación y medida, especialmente mediante automatización y miniaturización. El desarrollo de metodologías directas de análisis sin uso de reactivos o disolventes y que, por tanto, no generen desechos tóxicos ni peligrosos. Las técnicas espectroscópicas junto con el uso de la quimiometría pueden ser una buena alternativa a los métodos tradicionales, ya que se pueden r…
Group Delay and Spectral Phase Retrieval of Light Pulses by Spectral Intensity Measurements
2022
We discuss a method to determine both the group delay and the phase of a given pulse in the Fourier optics domain. The proposal is based on the measurement of two intensity spectra, before and after a known quadratic phase modulation. A simple analytical equation is then used to determine the group delay in one step. If necessary, the spectral phase can be determined by simple spectral integration of the determined group delay. The proposal is supported by various numerical results and an experimental measurement to prove the concept.