Search results for "Trap"
showing 10 items of 2144 documents
Light trapping by plasmonic nanoparticles
2020
Abstract Metallic nanoparticles sustaining localized surface plasmon resonances are of great interest for enhancing light trapping in thin film photovoltaics. In this chapter, we explore the correlation between the structural and optical properties of self-assembled silver nanostructures fabricated by a solid-state dewetting process on various substrates relevant for silicon photovoltaics and later integrated into plasmonic back reflectors. Our study allows us to optimize the performance of nanostructures by identifying the fabrication conditions in which desirable circular and uniformly spaced nanoparticles are obtained. Second, we introduce a novel optoelectronic spectroscopic method that…
Plasmonic nanostructures for light trapping in photovoltaic
Metallic nanoparticles (NPs), sustaining localized surface plasmon resonances, are currently of great interest for enhancing light trapping in thin film solar cells. To be directly applicable in the photovoltaic industry, the NPs fabrication needs to be simple, reliable, low-cost and scalable. As such, self-assembly processes are most commonly used, and Ag is the preferred material, due to its high radiative efficiency and low imaginary permittivity. After exploring the correlation between structural and optical properties of Ag NPs fabricated by solid- state dewetting process on various substrates, we identified the fabrication conditions in which desirable NPs are obtained, but we also e…
Dilatant plasticity applied to Alpine collision: ductile void growth in the intraplate area beneath the Eifel volcanic field
1998
The Eifel is located in the middle of the European plate far away from any active plate boundary, yet it appears to be a maximum of intraplate tectonic activity. A map of intraplate seismic energy flow shows that the Eifel is linked to the Alpine collisional belt via a narrow seismoactive shear zone. Two parallel Quaternary volcanic zones (the East Eifel Volcanic Zone EEVZ and the West Eifel Volcanic Zone WEVZ) line up with the seismogenic shear zone. Xenoliths ejected from these volcanic lineaments indicate upper mantle shearing by dynamic recrystallization textures and metasomatized chemistry. Important CO2-dominated mantle degassing observed in mineral springs, lakes or dry degassing sug…
Partially time invariant panel data regression
2023
When dealing with panel data, considering the variation over time of the variable of interest allows to get rid of potential individual effects. Even though the outcome variable has a continuous distribution, its variation over time can be equal to zero with a strictly positive probability and thus its distribution is a mixture of a mass at zero and a continuous distribution. We introduce a parametric statistical model based on conditional mixtures, build estimators for the parameters related to the conditional probability of no variation and to the conditional expectation related to the continuous part of the distribution and derive their asymptotic consistency and normality under a specif…
Alternating, all-trans polyenynes: Model compounds for poly(diacetylene)s with defined conjugation length
1994
The syntheses of polyenynes as model compounds for poly(diacetylene)s (PDAs) are described. Variation of properties (UV–VIS, Raman, NMR and bond geometries) as a function of the chain length was investigated. After extrapolation to infinite chain length these data were compared to those for PDAs. From UV–VIS spectra a value of λ = 551 nm (2.25 eV) was calculated corresponding to the electronic transition of a single polyenyne chain. This energy is located at the low energy end of a yellow PDA solution spectrum. From Raman scattering v(CC) = 2108–2128 cm−1 and v(CC) = 1505–1532 cm−1 were calculated after extrapolation. Similarly sp-C13C NMR data yielded a shift of δ = 100 ppm. These data are…
Analysis of Phenolic Compounds in Commercial Cannabis sativa L. Inflorescences Using UHPLC-Q-Orbitrap HRMS
2020
Industrial hemp (Cannabis sativa L. Family Cannabaceae) contains a vast number of bioactive relevant compounds, namely polyphenols including flavonoids, phenolic acids, phenol amides, and lignanamides, well known for their therapeutic properties. Nowadays, many polyphenols-containing products made of herbal extracts are marketed, claiming to exert health-promoting effects. In this context, industrial hemp inflorescence may represent an innovative source of bioactive compounds to be used in nutraceutical formulations. The aim of this work was to provide a comprehensive analysis of the polyphenolic fraction contained in polar extracts of four different commercial cultivars (Kompoti, Tiborszal…
Fast analysis of polyphenols and alkaloids in cocoa-based products by ultra-high performance liquid chromatography and Orbitrap high resolution mass …
2018
The cocoa varieties Criollo, Forastero and Trinitario, which have different organoleptic properties, quite often are mixed together in cocoa-based products. The objective of this work was to develop a rapid method for the simultaneous determination of polyphenols (n = 35) and alkaloids (n = 2) in cocoa-based products by using the high throughput advantages provided by the Q Exactive Hybrid Quadrupole-Orbitrap Mass Spectrometer (FIRMS). The proposed procedure was optimized and validated in terms of selectivity and specificity (mass accuracy 0.990), accuracy (recovery range from 89.1 to 112.4%) and precision (relative standard deviation < 10%). The method was applied to 80 cocoa-based samples…
Size dependent light absorption modulation and enhanced carrier transport in germanium quantum dots devices
2015
Quantum confinement in closely packed arrays of Ge quantum dots (QDs) was studied for energy applications. In this work, we report an efficient tuning mechanism of the light harvesting and detection of Ge QDs. Thin films of SiGeO alloys, produced by rf-magnetron sputtering, were annealed at 600 degrees C in N-2 to induce precipitation of small amorphous Ge QDs into the oxide matrix. Varying the Ge content, the QD size was tailored between 2 and 4 nm, as measured by high resolution transmission electron microscopy. X-ray photoelectron spectroscopy (XPS) measurements indicate the formation of pure SiO2, as well as the presence of a sub-stoichiometric Ge oxide shell at the QD interface. Light …
Comparison of parallel implementation of some multi-level Schwarz methods for singularly perturbed parabolic problems
1999
Abstract Parallel multi-level algorithms combining a time discretization and an overlapping domain decomposition technique are applied to the numerical solution of singularly perturbed parabolic problems. Two methods based on the Schwarz alternating procedure are considered: a two-level method with auxiliary “correcting” subproblems as well as a three-level method with auxiliary “predicting” and “correcting” subproblems. Moreover, modifications of the methods using time extrapolation on subdomain interfaces are investigated. The emphasis is given to the description of the algorithms as well as their computer realization on a distributed memory multiprocessor computer. Numerical experiments …
The Art of Bootstrapping
2020
Language workbenches are used to define languages using appropriate meta-languages. Meta-languages are also just languages and can, therefore, be defined using themselves. The process is called bootstrapping and is often difficult to achieve.