Quantum phase slips: from condensed matter to ultracold quantum gases D'Errico, C.; Abbate, S. Scaffidi; Modugno, G.
Philosophical transactions - Royal Society. Mathematical, Physical and engineering sciences/Philosophical transactions - Royal Society. Mathematical, physical and engineering sciences,
12/2017, Letnik:
375, Številka:
2108
Journal Article
Recenzirano
Odprti dostop
Quantum phase slips (QPS) are the primary excitations in one-dimensional superfluids and superconductors at low temperatures. They have been well characterized in most condensed-matter systems, and ...signatures of their existence have been recently observed in superfluids based on quantum gases too. In this review, we briefly summarize the main results obtained on the investigation of phase slips from superconductors to quantum gases. In particular, we focus our attention on recent experimental results of the dissipation in one-dimensional Bose superfluids flowing along a shallow periodic potential, which show signatures of QPS.
This article is part of the themed issue ‘Breakdown of ergodicity in quantum systems: from solids to synthetic matter’.
We have developed a dielectric-barrier-discharge propane burner where propane is activated prior to being mixed with air and burned. In contrast to most work reported by others, combustion in our ...apparatus occurs away from the plasma region, thereby greatly reducing electric field effects, thus providing more insight into the role played by plasma chemistry. Flame flashback images were recorded as a function of the separation between the propane plasma and injected air, and the mixing length of the activated propane/air mixture. The lifetime of activated propane was found to be about 150 ms, while the lifetime of an activated propane/air mixture was measured to be about 300 ms. Using a gas-chromatograph diagnostic, H 2 , CH 4 , C 2 H 2 , C 2 H 4 , and C 2 H 6 were identified as the principal propane-discharge fragments, however, these are not the dominant species causing flame flashback behavior. The presence of reactive radical species is suggested to be a main factor governing flame flashback
This paper reports on studies obtained from RF-driven atmospheric-pressure plasma-jet excitation of methane and ethane. Differentiation with other works is achieved in that others have considered ...hydrocarbon decomposition at either low pressure or high temperature. In our experiments, we can clarify the effect of pure-plasma treatment of hydrocarbons, as opposed to the thermal effect of gas heating that results in pyrolysis. Gas-chromatography analysis was used to detect and quantify the main decomposition products. Kinetic modeling of the pertinent chemistry was performed by dividing the reactive system in two main parts: a plasma region where the electron impact processes leading to decomposition are considered and a postplasma region where recombination of nonstable species occurs. A reasonable qualitative agreement between the experimentally measured by-product concentrations and the calculations was achieved. It is observed that our proposed recombination mechanism correctly predicts ethane and ethylene formation from a discharge and methane, ethylene, propane, and acetylene formation from the discharge. By means of calculations, the main role of radicals in the pertinent hydrocarbon chemistry under nonthermal plasma conditions is confirmed.
It is well known that electric fields can influence combustion processes. When the magnitude of an external applied electric field exceeds the breakdown field of the fuel gas or fuel/oxidizer ...mixture, plasma effects dominate. The earlier work in the field of plasma-assisted combustion has demonstrated that dielectric-barrier-discharge (DBD)-driven nonthermal plasmas (NTPs) can increase flame speed and extend the combustion of hydrocarbon fuel gases into very lean-burn regimes. In this paper, results on the decomposition of ethane (C 2 H 6 ) by DBDs at atmospheric pressure will be presented. The authors have chosen ethane for this paper because its gaseous electronics properties (electron-impact dissociation cross sections, drift velocity) are available in the literature. A subsequent paper will present results on the calculated yield of DBD-driven plasma decomposition products of ethane, as predicted by plasma-chemistry modeling. In this paper, results on experiments carried out to determine the decomposition products of ethane, as measured by gas chromatography are presented. An atmospheric-pressure DBD reactor processed a flowing gas stream of chemically pure ethane in the regime of plasma specific energy ranging from 1200 to 2400 J/std lit. The major stable decomposition products were H 2 , CH 4 , C 2 H 2 , and C 2 H 4 . These results are important in assessing the possibility of using NTPs to enhance the combustion of hydrocarbons
Hydrogasification of carbon (C + 2H 2 rarr CH 4 ) was studied using a microwave plasma in atmospheric pressure Ar/H 2 mixtures. When the activated Ar/H 2 gas stream interacted with cold carbon ...particles downstream of the microwave cavity, CH 4 (methane) was the only stable gasification product, as measured by gas chromatography. However, when carbon particles were injected into the plasma within the microwave cavity, both C 2 H 2 (acetylene) and C 2 H 4 (ethylene) were measured in addition to CH 4 . To identify a gasification mechanism by the microwave plasma, UV emission and minimum operational power required to maintain plasma were measured. From the experimental results, the initial reaction step leading to CH 4 is thought to be a chemisorption-desorption reaction of hydrogen radical onto a carbon particle. For the C 2 H 2 and C 2 H 4 generation, hydrogen ion reaction with a carbon particle is suggested.
Quantum phase slips: from condensed matter to ultracold quantum gases D'Errico, C.; Abbate, S. Scaffidi; Modugno, G.
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
12/2017, Letnik:
375, Številka:
2108
Journal Article
Recenzirano
Quantum phase slips (QPS) are the primary excitations in one-dimensional superfluids and superconductors at low temperatures. They have been well characterized in most condensed-matter systems, and ...signatures of their existence have been recently observed in superfluids based on quantum gases too. In this review, we briefly summarize the main results obtained on the investigation of phase slips from superconductors to quantum gases. In particular, we focus our attention on recent experimental results of the dissipation in one-dimensional Bose superfluids flowing along a shallow periodic potential, which show signatures of QPS. This article is part of the themed issue 'Breakdown of ergodicity in quantum systems: from solids to synthetic matter'.
Today the most important problem in the work place is psychological abuse, which may affect the health because of high levels of stress and anxiety.
There is evidence that most psychiatric disorders ...are associated with increased oxidative stress but nothing is reported about the presence of oxidative stress in mobbing victims.
This study has been carried out in a group of 19 patients affected by workplace mobbing-due adjustment disorders, in comparison with 38 healthy subjects, to evaluate whether oxidative stress may be induced by mobbing.
Serum levels of protein carbonyl groups and of nitrosylated proteins, biological markers of oxidative stress conditions, were higher than those measured in healthy subjects.
These findings may contribute to a better understanding of the redox homeostasis dysregulation occurring in victims of workplace mobbing.
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