Search results for "Phosphor"
showing 10 items of 1952 documents
Warm white LED light by frequency down-conversion of mixed yellow and red Lumogen®
2013
This work reports on the benefits and promising opportunities offered by white LED hybrid technology, based on a mixing perylene-based dyes in order to obtain a warm white light for frequency-down conversion. In a standard Ce:YAG-based white LED, the white light appears cold due to the weakness of red wavelength components in the emission spectrum. In order to obtain a warmer white, one possible solution is to add a red phosphor to the yellow one to move the chromatic coordinates properly, though the luminous efficiency drastically decreases due to the increased light absorption of the coating layer. It is generally believed that the low efficiency of warm white LEDs is the main issue today…
Hydrogenation of White Phosphorus to Phosphane with Rhodium and Iridium Trihydrides.
1998
Only one of the four P atoms of P4 reacts with rhodium and iridium trihydrides [(triphos)MH3 ] to provide phosphane [Eq. (a)]. The resulting cyclo-P3 fragment is efficiently scavenged by the metal fragment to give the complexes [(triphos)M(η3 -P3 )]. A mechanism accounting for the hydrogenation reaction is proposed in which the complexes [(triphos)MH(η1 :η1 -P4 )] and [(triphos)M(η1 :η2 -HP4 ] are intermediates. The latter complex contains the unprecedented hydridotetraphosphane ligand HP4- .
Spray pyrolysis synthesis and characterization of Mg1-xSrxMoO4 heterostructure with white light emission
2020
[EN] Molybdates are inorganic materials with great potential in white phosphors application, being an alternative to traditional lighting sources. In this study, we report the synthesis and characterization of Mg1-xSrxMoO4 (x = 0, 0.25, 0.50, 0.75, and 1) powders with white light-emitting properties. Using X-ray diffraction, the formation of the monoclinic beta-MgMoO4 phase was observed for x = 0 and the formation of the tetragonal scheelite phase of SrMoO4 was observed for x = 1. The formation of a heterostructure composed of both phases was found for compositions with x = 0.25, 0.50 and 0.75. Scanning and trasmission electron microscopy images showed that the Mg1-xSrxMoO4 particles exhibi…
Function and evolution of vertebrate globins.
2014
Globins are haem-proteins that bind O2 and thus play an important role in the animal's respiration and oxidative energy production. However, globins may also have other functions such as the decomposition or production of NO, the detoxification of reactive oxygen species or intracellular signalling. In addition to the well-investigated haemoglobins and myoglobins, genome sequence analyses have led to the identification of six further globin types in vertebrates: androglobin, cytoglobin, globin E, globin X, globin Y and neuroglobin. Here, we review the present state of knowledge on the functions, the taxonomic distribution and evolution of vertebrate globins, drawing conclusions about the fu…
Wee1 inhibition potentiates Wip1-dependent p53-negative tumor cell death during chemotherapy
2016
AbstractInactivation of p53 found in more than half of human cancers is often associated with increased tumor resistance to anti-cancer therapy. We have previously shown that overexpression of the phosphatase Wip1 in p53-negative tumors sensitizes them to chemotherapeutic agents, while protecting normal tissues from the side effects of anti-cancer treatment. In this study, we decided to search for kinases that prevent Wip1-mediated sensitization of cancer cells, thereby interfering with efficacy of genotoxic anti-cancer drugs. To this end, we performed a flow cytometry-based screening in order to identify kinases that regulated the levels of γH2AX, which were used as readout. Another criter…
Novel synthesis of up-conversion phosphor based on rare-earth doped NaLaF4
2011
In this work Er3+ doped NaLaF4 material has been synthesized Along with the description of the synthesis route, luminescence spectra and decay kinetics of both traditional and up-conversion luminescence of Er3+ will be presented for different Er3+ doping levels. It will be shown that the main mechanisms involved in the creation of the up-conversion luminescence in NaLaF4:Er3+ under excitation at about 975 nm are excited state absorption and energy transfer. Relative impact of either of the mechanisms in NaLaF4:Er3+ depends on both the concentration of Er3+ and on the excitation wavelength: the increase of either the concentration or the excitation wavelength leads to the prevalence of energ…
Calibration and simulation of ASM2d at different temperatures in a phosphorous removal pilot plant
2006
In this work, an organic and nutrient removal pilot plant was used to study the temperature influence on phosphorus accumulating organisms. Three experiments were carried out at 13, 20 and 24.5 degrees C, achieving a high phosphorus removal percentage in all cases. The ASM2d model was calibrated at 13 and 20 degrees C and the Arrhenius equation constant was obtained for phosphorus removal processes showing that the temperature influences on the biological phosphorus removal subprocesses in a different degree. The 24.5 degrees C experiment was simulated using the model parameters obtained by means of the Arrhenius equation. The simulation results for the three experiments showed good corresp…
Size control of InAs∕InP(001) quantum wires by tailoring P∕As exchange
2004
The size and emission wavelength of self-assembled InAs∕InP(001) quantum wires (QWrs) is affected by the P∕As exchange process. In this work, we demonstrate by in situ stress measurements that P∕As exchange at the InAs∕InP interface depends on the surface reconstruction of the InAs starting surface and its immediate evolution when the arsenic cell is closed. Accordingly, the amount of InP grown on InAs by P∕As exchange increases with substrate temperature in a steplike way. These results allow us to engineer the size of the QWr for emission at 1.3 and 1.55 μm at room temperature by selecting the range of substrate temperatures in which the InP cap layer is grown.
Vascular oxidative stress, nitric oxide and atherosclerosis.
2014
In the vascular wall, reactive oxygen species (ROS) are produced by several enzyme systems including NADPH oxidase, xanthine oxidase, uncoupled endothelial nitric oxide synthase (eNOS) and the mitochondrial electron transport chain. On the other hand, the vasculature is protected by antioxidant enzyme systems, including superoxide dismutases, catalase, glutathione peroxidases and paraoxonases, which detoxify ROS. Cardiovascular risk factors such as hypercholesterolemia, hypertension, and diabetes mellitus enhance ROS generation, resulting in oxidative stress. This leads to oxidative modification of lipoproteins and phospholipids, mechanisms that contribute to atherogenesis. In addition, oxi…
Near-IR to Near-IR Upconversion Luminescence in Molecular Chromium Ytterbium Salts
2020
Abstract Upconversion photoluminescence in hetero‐oligonuclear metal complex architectures featuring organic ligands is an interesting but still rarely observed phenomenon, despite its great potential from a basic research and application perspective. In this context, a new photonic material consisting of molecular chromium(III) and ytterbium(III) complex ions was developed that exhibits excitation‐power density‐dependent cooperative sensitization of the chromium‐centered 2E/2T1 phosphorescence at approximately 775 nm after excitation of the ytterbium band 2F7/2→2F5/2 at approximately 980 nm in the solid state at ambient temperature. The upconversion process is insensitive to atmospheric ox…