Superconductivity in oxygen

Shimizu, Katsuya; Suhara, K.; Ikumo, M.; Eremets, M. I.; Amaya, Kiichi

doi:10.1038/31656

Cited by 260 publications

(170 citation statements)

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“…A superconducting phase has also been found at 0.6 K near 100 GPa 11 . In addition, the solid phases exhibit a complex magnetic structure with various degrees of ordering due to a strong exchange interaction between O 2 molecules that becomes suppressed under pressure and acts in tandem with weak van der Waals forces holding the lattice together 1,12,13 .…”

Section: Introductionmentioning

confidence: 88%

First-principles equation of state and electronic properties of warm dense oxygen

Driver

Soubiran

Zhang

et al. 2015

The Journal of Chemical Physics

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We perform all-electron path integral Monte Carlo (PIMC) and density functional theory molecular dynamics (DFT-MD) calculations to explore warm dense matter states of oxygen. Our simulations cover a wide density-temperature range of 1 − 100 g cm −3 and 10 4 − 10 9 K. By combining results from PIMC and DFT-MD, we are able to compute pressures and internal energies from first-principles at all temperatures and provide a coherent equation of state. We compare our first-principles calculations with analytic equations of state, which tend to agree for temperatures above 8×10 6 K. Pair-correlation functions and the electronic density of states reveal an evolving plasma structure and ionization process that is driven by temperature and density. As we increase the density at constant temperature, we find that the ionization fraction of the 1s state decreases while the other electronic states move towards the continuum. Finally, the computed shock Hugoniot curves show an increase in compression as the first and second shells are ionized.

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Section: Introductionmentioning

confidence: 88%

First-principles equation of state and electronic properties of warm dense oxygen

Driver

Soubiran

Zhang

et al. 2015

The Journal of Chemical Physics

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“…We interpret the enhancement of the O 2 molecular polarizability as an indication that the molecules at these conditions are distorted. Although, to our knowledge, there are no theoretical studies of fluid oxygen in the Mbar pressure range, several predictions have been made [15] for the solid in conjunction with the reported metallization of solid oxygen under static high pressure [8,9]. The reported metallization pressure for the low temperature solid, 0.96M bar, is very close to the onset of the metallic conduction in the fluid around 1.2M bar.…”

mentioning

confidence: 85%

“…Given the "simple" nature of their interactions, the homonuclear diatomic molecular species, e.g. hydrogen [4][5][6], oxygen [7][8][9], nitrogen [10] and the halogens [11], have been intensively studied using both static and dynamic high pressure techniques.We report in this letter the first experimental evidence for a non-metal/metal transition in the molecular fluid phase of oxygen under high dynamic compression. Oxygen has very rich physics at high pressure.…”

mentioning

confidence: 99%

“…Oxygen has very rich physics at high pressure. Since dramatic color changes were reported in the 100kbar pressure range [12], the high pressure solid phases of oxygen have been extensively investigated using structural [13][14][15], optical [7,8] and transport techniques [9]. A metallic state and evidence for superconductivity have been identified in the solid around 1M bar at very low temperatures [8,9].…”

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confidence: 99%

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High Pressure Insulator-Metal Transition in Molecular Fluid Oxygen

2001

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We report the first experimental evidence for a metallic phase in fluid molecular oxygen. Our electrical conductivity measurements of fluid oxygen under dynamic quasi-isentropic compression show that a non-metal/metal transition occurs at 3.4 fold compression, 4500 K and 1.2 Mbar. We discuss the main features of the electrical conductivity dependence on density and temperature and give an interpretation of the nature of the electrical transport mechanisms in fluid oxygen at these extreme conditions. PACS numbers: 71.30.+h, 62.50.+p, 77.22.Ej The transition of condensed matter between electrically conducting and insulating states is a topic of wide scientific interest, whose relevance ranges from superconductivity to collosal magnetoresistance [1], to more recently thermoelectricity [2]. The metal/insulator transition has received renewed attention during the past decade in the context of high pressure research [3]. Although much progress has been made in developing experimental, theoretical and computational tools appropriate for the study of the metal/insulator transition at extreme conditions, our present understanding is mostly phenomenological and still incomplete. Given the "simple" nature of their interactions, the homonuclear diatomic molecular species, e.g. hydrogen [4][5][6], oxygen [7][8][9], nitrogen [10] and the halogens [11], have been intensively studied using both static and dynamic high pressure techniques.We report in this letter the first experimental evidence for a non-metal/metal transition in the molecular fluid phase of oxygen under high dynamic compression. Oxygen has very rich physics at high pressure. Since dramatic color changes were reported in the 100kbar pressure range [12], the high pressure solid phases of oxygen have been extensively investigated using structural [13][14][15], optical [7,8] and transport techniques [9]. A metallic state and evidence for superconductivity have been identified in the solid around 1M bar at very low temperatures [8,9]. The properties of the liquid on the other hand have not been explored much, due to experimental difficulties and also technical and conceptual challenges for theory.New insights on the physics of warm dense matter were provided by dynamic compression experiments on hydrogen [5,6]. We present the first electrical conductivity measurements of fluid oxygen under dynamic quasiisentropic compression between 0.3 and 1.9M bar. In our experiments fluid oxygen reaches up to 4-fold compression and temperatures below 7000K, conditions never before reached experimentally. We note that these conditions are similar with the ones found in the interiors of the giant planets, where oxygen is a major constituent, and that these conductivity measurements may be instrumental in explaining the origins of the planetary magnetic fields.We measured the electrical resistance of quasiisentropically compressed oxygen starting from high purity (99.995%), disk shaped liquid samples [16] of density d 0 = 1.202g/cm 3 at T 0 = 77K and atmospheric pressure. The hig...

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“…Although it contains a complete set of desaturase genes for the biosynthesis of both ARA (n-6) and EPA (n-3), at physiological growth temperatures, it produces ARA as the only major VL-PUFA. This regulation of PUFA metabolic flux is partly due to the substrate specificity of the ∆6 Des Table 2, Sakuradani and Shimizu, 2003;Sakuradani et al, 2005;Zhu et al, 2002) which prefers n-6 fatty acid LA to n-3 ALA as substrate and its ω-3 Des must be repressed at physiological growth temperature (Shimizu et al, 1998). Although the ω-3 Des have been cloned and biochemically studied in a few microorganisms Table 5, (Gellerman and Schlenk, 1979;Pereira et al, 2004;Sakamoto et al, 1994;Wada and Murata, 1990), its expression level in oleaginous microorganisms has not been determined so far.…”

Section: Molecular Switch Of Microorganisms That Produce N-6 Fatty Acmentioning

confidence: 99%

Molecular Switch That Controls the Flux of Linoleic Acid Into N-6 or N-3 Polyunsaturated Fatty Acids in Microorganisms

Wang

Chen²,

Zhang

et al. 2014

American Journal of Biochemistry and Biotechnology

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Polyunsaturated Fatty Acids (PUFA) of the n-6 and n-3 series play important roles in nutrition. Microorganisms are important sources of n-6 and n-3 fatty acids; however, most produce either n-6 or n-3 fatty acids as the major PUFAs and very few produce both. This differential production suggests that PUFAs metabolic pathway is strictly controlled in microorganisms. The major pathway of n-6/n-3 faty acids biosynthesis in lower eukaryotes is composed of ∆12 Desaturase (Des), ω3 Des (∆15, ∆17), ∆6 Des, ∆6 Elongase (Elo), ∆5 Des, ∆5 Elo and ∆4 Des, among which ∆6 Des and ∆15 (ω3) Des, located at the branch point of PUFAs metabolic pathways, are key regulators of the flux of linoleic acid (18:2 n-6) into either n-6 or n-3 fatty acid metabolic pathways. These latter two enzymes work together as a molecular switch that control the production of n-6/n-3 fatty acids. However the mechanism of the molecular switch is, so far, not clear. This review summarizes the recent advancement of the molecular base of the differentail production of n-6 or n-3 PUFAs in microorganisms.

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Superconductivity in oxygen

Cited by 260 publications

References 10 publications

First-principles equation of state and electronic properties of warm dense oxygen

First-principles equation of state and electronic properties of warm dense oxygen

High Pressure Insulator-Metal Transition in Molecular Fluid Oxygen

Molecular Switch That Controls the Flux of Linoleic Acid Into N-6 or N-3 Polyunsaturated Fatty Acids in Microorganisms

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