Search results for "ICON"
showing 10 items of 3539 documents
An increased F2-laser damage in ‘wet’ silica glass due to atomic hydrogen: A new hydrogen-related E′-center
2006
Abstract A dramatic increase of F2-laser induced room temperature-stable point defects in ‘wet’ synthetic silica glass occurs when irradiation temperature is lowered to 80 K. Contrary to the predictions based on the established models of defect processes, a large part of defects induced at 80 K remains stable also at the room temperature. The intensities of the laser-induced optical absorption bands of the non-bridging oxygen hole centers (2.0 and 4.8 eV) and E′-centers (5.8 eV) are comparable to those created by neutron irradiation (1018 n/cm2). A growth of infrared absorption peak at 2237 cm−1 indicates creation of silicon hydride (SiH) groups. A study of irradiation dose dependences and …
Intrinsic absorption threshold of stishovite and coesite
2004
Abstract The optical absorption spectra of the small mono-crystals samples of stishovite and coesite were studied at first. The intrinsic absorption threshold of stishovite is determined at 8.75 eV, being probably, highest in the family of different crystalline polymorph modifications of silicon dioxide. The absorption spectrum of stishovite is independent of temperature (studied in the range 290–450 K). The intrinsic absorption threshold of coesite mono-crystal situated near 8.6 eV at 293 K, coincides within experimental errors with that of α-quartz crystal, and depends on temperature, as used to be for the tetrahedron structured silicon dioxide crystalline modifications. A broad absorptio…
María Magdalena. Continuidad y variación en la cultura audiovisual (1897-2014)
2017
El objetivo principal de esta tesis consiste en analizar la presencia de María Magdalena en las producciones audiovisuales del periodo comprendido entre 1897 y 2014. Dichas producciones proceden de Europa, Estados Unidos, Canadá y México. El marco metodológico general a partir del que se plantea el análisis es la iconología, entendida como Zwichenraum o tierra de confluencias. En concreto, la noción de continuidad y variación, iniciada por Aby Warburg y continuada por Fritz Saxl, es la principal cuestión teórica en la que se basa la aproximación. El estudio se lleva a cabo en perspectiva diacrónica con el objetivo de detectar dichas fases de continuidad y variación del personaje a lo largo …
Radiation from multi-GeV electrons and positrons in periodically bent silicon crystal
2014
A periodically bent Si crystal is shown to efficiently serve for producing highly monochromatic radiation in a gamma-ray energy spectral range. A short-period small-amplitude bending yields narrow undulator-type spectral peaks in radiation from multi-GeV electrons and positrons channeling through the crystal. Benchmark theoretical results on the undulator are obtained by simulations of the channeling with a full atomistic approach to the projectile-crystal interactions over the macroscopic propagation distances. The simulations are facilitated by employing the MBN Explorer package for molecular dynamics calculations on the meso-, bio- and nano-scales. The radiation from the ultra-relativist…
Channeling experiments at planar diamond and silicon single crystals with electrons from the Mainz Microtron MAMI
2020
Line structures were observed for (110) planar channeling of electrons in a diamond single crystal even at a beam energy of 180 MeV . This observation motivated us to initiate dechanneling length measurements as function of the beam energy since the occupation of quantum states in the channeling potential is expected to enhance the dechanneling length. High energy loss signals, generated as a result of emission of a bremsstrahlung photon with about half the beam energy at channeling of 450 and 855 MeV electrons, were measured as function of the crystal thickness. The analysis required additional assumptions which were extracted from the numerical solution of the Fokker-Planck equation. Prel…
Performance of a Chromolith RP-18e column for the screening of β-blockers
2009
The chromatographic performance of a monolithic column (Chromolith RP-18e) was comprehensively examined in the isocratic separation of ten beta-blockers, using ACN-water mobile phases, and compared with the performance of three microparticulate RP columns manufactured with different types of silica: Spherisorb ODS-2, Kromasil C18 and XTerra MS C18. The comparison considered the analysis time, selectivity, peak shape (column efficiency and asymmetry) and resolution, and was extended to a wide range of mobile phase compositions. The Chromolith column showed good performance for the analysis of beta-blockers with regard to the packed columns. In terms of selectivity and analysis time, the grea…
Sample Preparation Improvement in Polycyclic Aromatic Hydrocarbons Determination in Olive Oils by Gel Permeation Chromatography and Liquid Chromatogr…
2005
Abstract The determination of 15 polycyclic aromatic hydrocarbons (PAHs) in olive oil samples has been improved in order to obtain a fast methodology with a low limit of detection through the combination of liquid–liquid extraction with acetonitrile and preparative gel permeation chromatography (GPC) prior to the injection of purified extracts into a C18 column. Acetonitrile–water was used as the mobile phase with a gradient from 50 to 95%, w/w, acetonitrile in 30 min. The oven temperature was maintained at 15°C, and fluorometric detection was made at a fixed excitation wavelength of 264 nm and variable, optimal emission wavelength for each analyte ranging from 352 nm for 11-H-benzo(b)fluor…
An experimental method for the determination of the photon flow reflected and absorbed by aqueous dispersions containing polycrystalline solids in he…
1991
An experimental method for the evaluation of the photon flow reflected and absorbed by aqueous dispersions containing polycrystalline solids is proposed. The method is based on actinometric measurements. It is shown that the values obtained are independent of the particle sizes and of the concentration of the solids at least in the experimental conditions and in the range used in the present study (particle size range: 40–500 μm; solids concentration: 0.1–2 g liter−1). The results suggest that the values obtained should be attributed to the interfaces formed between the surface of the solids and the medium. The method is applied to a photocatalytic reaction, namely to the photodegradation o…
Targeted-lung delivery of dexamethasone using gated mesoporous silica nanoparticles. A new therapeutic approach for acute lung injury treatment
2021
Acute lung injury (ALI) is a critical inflammatory syndrome, characterized by increased diffuse inflammation and severe lung damage, which represents a clinical concern due to the high morbidity and mortality in critical patients. In last years, there has been a need to develop more effective treatments for ALI, and targeted drug delivery to inflamed lungs has become an attractive research field. Here, we present a nanodevice based on mesoporous silica nanoparticles loaded with dexamethasone (a glucocorticoid extensively used for ALI treatment) and capped with a peptide that targets the TNFR1 receptor expressed in pro-inflammatory macrophages (TNFR-Dex-MSNs) and avoids cargo leakage. TNFR-D…
NOseq: amplicon sequencing evaluation method for RNA m6A sites after chemical deamination
2020
Abstract Methods for the detection of m6A by RNA-Seq technologies are increasingly sought after. We here present NOseq, a method to detect m6A residues in defined amplicons by virtue of their resistance to chemical deamination, effected by nitrous acid. Partial deamination in NOseq affects all exocyclic amino groups present in nucleobases and thus also changes sequence information. The method uses a mapping algorithm specifically adapted to the sequence degeneration caused by deamination events. Thus, m6A sites with partial modification levels of ∼50% were detected in defined amplicons, and this threshold can be lowered to ∼10% by combination with m6A immunoprecipitation. NOseq faithfully d…