Search results for "vacuum"
showing 10 items of 352 documents
A theoretical study of the rotational structure of the ϵ(0,0) band of NO
2009
This study has been focused on the ϵ(0,0) band of the nitric oxide molecule, associated with the absorption electronic transition D2Σ+X 2Π, in the energetic vacuum ultraviolet region. A temperature of 295 K has been considered. The Molecular Quantum Defect Orbital (MQDO) methodology, with which reliable spectroscopic data have been reached in the γ(0,0), δ(0,0), and δ(1,0) bands of the same molecule, has also been used for these calculations. We hope that the present results might be of straightforward use in atmospheric and interstellar chemistry. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
A symmetry adapted approach to the dynamic Jahn-Teller problem: Application to mixed-valence polyoxometalate clusters with keggin structure
2012
In this article, we present a symmetry-adapted approach aimed to the accurate solution of the dynamic vibronic problem in large scale Jahn-Teller (JT) systems. The algorithm for the solution of the eigen-problem takes full advantage of the point symmetry arguments. The system under consideration is supposed to consist of a set of electronic levels mixed by the active JT and pseudo JT vibrational modes. Applying the successive coupling of the bosonic creation operators, we introduce the irreducible tensors that are called multivibronic operators. Action of the irreducible multivibronic operators on the vacuum state creates the vibrational symmetry adapted basis that is subjected to the Gram-…
1H-naphtho[2,1-b]thiete and 2H-naphtho[2,3-b]thiete- synthesis and reactivity
1994
Abstract The title compounds 4 and 8 are obtained by flash vacuum pyrolysis of the corresponding hydroxymethylthionaphthols 3 and 7. Whereas 4 shows a smooth ring opening on heating, 8 is thermally stable but reacts photochemically. The different behavior is explained on the basis of an MNDO calculation. The valence isomers 4′ and 8′ represent thioquinonemethides, which are highly reactive components in [12π + 2π]cycloaddition processes (4 → 9, 10, 11; 8 → 12).
ChemInform Abstract: 1H-Naphtho(2,1-b)thiete and 2H-Naphtho(2,3-b)thiete - Synthesis and Reactivity.
2010
Abstract The title compounds 4 and 8 are obtained by flash vacuum pyrolysis of the corresponding hydroxymethylthionaphthols 3 and 7. Whereas 4 shows a smooth ring opening on heating, 8 is thermally stable but reacts photochemically. The different behavior is explained on the basis of an MNDO calculation. The valence isomers 4′ and 8′ represent thioquinonemethides, which are highly reactive components in [12π + 2π]cycloaddition processes (4 → 9, 10, 11; 8 → 12).
Vacuum impregnation as a tool to introduce biopreservatives in gilthead sea bream fillets (Sparus aurata)
2015
Abstract The aim of this study was to determine the possible technological uses of biopreservation and vacuum impregnation techniques to extend shelf life of gilthead sea bream fillets. Two impregnation media were studied: a solution containing lactic acid bacteria (LAB) and a nisin solution. Vacuum impregnation was carried out at 4 °C. Fillets were immersed in a vessel containing the impregnation solution and vacuum was applied during 5 min. After this time atmospheric pressure was restored leaving samples under the liquid for 5 min more. Weight gain, physico-chemical properties (moisture, pH, water activity and TVBN), color and microbiological counts were studied during 15 days of storage…
Interfacial Modification for High-Efficiency Vapor-Phase-Deposited Perovskite Solar Cells Based on a Metal Oxide Buffer Layer.
2018
Vacuum deposition is one of the most technologically relevant techniques for the fabrication of perovskite solar cells. The most efficient vacuum-based devices rely on doped organic contacts, compromising the long-term stability of the system. Here, we introduce an inorganic electron-transporting material to obtain power conversion efficiencies matching the best performing vacuum-deposited devices, with open-circuit potential close to the thermodynamic limit. We analyze the leakage current reduction and the interfacial recombination improvement upon use of a thin (<10 nm) interlayer of C60, as well as a more favorable band alignment after a bias/ultraviolet light activation process. This wo…
The design of the DONES lithium target system
2019
Abstract In the framework of the EU fusion roadmap implementing activities, an accelerator-based Li(d,xn) neutron source called DONES (Demo-Oriented early NEutron Source) is being designed within the EUROfusion Work Package Early Neutron Source as an essential irradiation facility for testing candidate materials for DEMO reactor and future fusion power plants. DONES will employ a high speed liquid lithium jet struck by a 125 mA, 40 MeV deuteron beam to generate the intense neutron flux used to irradiate the material samples up to the desired level of displacement damage (˜10 dpa/fpy for iron in 0.3 l) and He production rates (˜10-13 appm He/dpa). In order to rapidly achieve a sound and stab…
Neutral volatile compounds in the raw milks from different species
1993
SummaryA comparative study was carried out on the flavour constituents of bovine, ovine, caprine and water buffalo fresh raw milks. The volatiles were isolated from milks by means of vacuum distillation and liquid–liquid extraction. Eighty neutral volatile compounds were identified using high resolution gas chromatography (HRGC) and HRGC-mass spectrometry. About 30 of these components have not been detected previously in milk. The volatiles in milk were similar for the four species, although several quantitative differences might explain the different odours. The volatiles consisted mainly of ethyl esters, especially those derived from butyric and hexanoic acids. Dimethylsulphone alone comp…
Design and implementation of a long-range low-power wake-up radio and customized DC-MAC protocol for LoRaWAN
2019
In this paper, we present the design and implementation of a long-rage wake-up radio (WuR) and customized duty cycled (DC) MAC protocol for wireless IoT devices. The WuRx achieves a sensivity of −70 dBm by consuming just 0.032 mA, thereby optimizing the energy consumption of battery powered long-range wireless IoT devices. Reducing the power consumption of these devices minimizes the overall costs when deployed in large scale.
Efficient Monolithic Perovskite/Perovskite Tandem Solar Cells
2016
Thin-film solar cells suffer from various types of recombination, of which leakage current usually dominates at lower voltages. Herein, we demonstrate first a three-order reduction of the shunt loss mechanism in planar methylammonium lead iodide perovskite solar cells by replacing the commonly used hole transport layer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) with a better hole-selective polyarylamine. As a result, these cells exhibit superior operation under reduced light conditions, which we demonstrate for the extreme case of moonlight irradiance, at which open-circuit voltages of 530 mV can still be obtained. By the shunt removal we also observe the VOC to dro…