scholarly journals Xenon iron oxides predicted as potential Xe hosts in Earth’s lower mantle

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Feng Peng ◽  
Xianqi Song ◽  
Chang Liu ◽  
Quan Li ◽  
Maosheng Miao ◽  
...  
Keyword(s):  
Iron Oxides ◽  
Lower Mantle ◽  
Search Algorithm ◽  
Mass Density ◽  
Mantle Minerals ◽  
Fe Oxides ◽  
Structure Search ◽  
Wide Range ◽  
Deep Earth ◽  
Calculated Mass

Abstract An enduring geological mystery concerns the missing xenon problem, referring to the abnormally low concentration of xenon compared to other noble gases in Earth’s atmosphere. Identifying mantle minerals that can capture and stabilize xenon has been a great challenge in materials physics and xenon chemistry. Here, using an advanced crystal structure search algorithm in conjunction with first-principles calculations we find reactions of xenon with recently discovered iron peroxide FeO2, forming robust xenon-iron oxides Xe2FeO2 and XeFe3O6 with significant Xe-O bonding in a wide range of pressure-temperature conditions corresponding to vast regions in Earth’s lower mantle. Calculated mass density and sound velocities validate Xe-Fe oxides as viable lower-mantle constituents. Meanwhile, Fe oxides do not react with Kr, Ar and Ne. It means that if Xe exists in the lower mantle at the same pressures as FeO2, xenon-iron oxides are predicted as potential Xe hosts in Earth’s lower mantle and could provide the repository for the atmosphere’s missing Xe. These findings establish robust materials basis, formation mechanism, and geological viability of these Xe-Fe oxides, which advance fundamental knowledge for understanding xenon chemistry and physics mechanisms for the possible deep-Earth Xe reservoir.

scholarly journals Diamond formation in an electric field under deep Earth conditions

2021 ◽  
Vol 7 (4) ◽  
pp. eabb4644
Author(s):  
Yuri N. Palyanov ◽  
Yuri M. Borzdov ◽  
Alexander G. Sokol ◽  
Yuliya V. Bataleva ◽  
Igor N. Kupriyanov ◽  
...  
Keyword(s):  
Electric Fields ◽  
Lithospheric Mantle ◽  
Isotope Fractionation ◽  
Diamond Formation ◽  
Mantle Minerals ◽  
Electrochemical Processes ◽  
Mantle Mineral ◽  
Deep Earth ◽  
Diamond Crystallization ◽  
Global Carbon

Most natural diamonds are formed in Earth’s lithospheric mantle; however, the exact mechanisms behind their genesis remain debated. Given the occurrence of electrochemical processes in Earth’s mantle and the high electrical conductivity of mantle melts and fluids, we have developed a model whereby localized electric fields play a central role in diamond formation. Here, we experimentally demonstrate a diamond crystallization mechanism that operates under lithospheric mantle pressure-temperature conditions (6.3 and 7.5 gigapascals; 1300° to 1600°C) through the action of an electric potential applied across carbonate or carbonate-silicate melts. In this process, the carbonate-rich melt acts as both the carbon source and the crystallization medium for diamond, which forms in assemblage with mantle minerals near the cathode. Our results clearly demonstrate that electric fields should be considered a key additional factor influencing diamond crystallization, mantle mineral–forming processes, carbon isotope fractionation, and the global carbon cycle.

scholarly journals Constraints on the composition and temperature of LLSVPs from seismic properties of lower mantle minerals

2021 ◽  
Vol 554 ◽  
pp. 116685
Author(s):  
Kenny Vilella ◽  
Thomas Bodin ◽  
Charles-Edouard Boukaré ◽  
Frédéric Deschamps ◽  
James Badro ◽  
...  
Keyword(s):  
Lower Mantle ◽  
Mantle Minerals ◽  
Seismic Properties

scholarly journals A Classification of Basic Helix-Loop-Helix Transcription Factors of Soybean

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Karen A. Hudson ◽  
Matthew E. Hudson
Keyword(s):  
Transcription Factors ◽  
Genome Sequence ◽  
Search Algorithm ◽  
Soybean Genome ◽  
Binding Potential ◽  
Future Research ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
Bhlh Genes ◽  
Wide Range

The complete genome sequence of soybean allows an unprecedented opportunity for the discovery of the genes controlling important traits. In particular, the potential functions of regulatory genes are a priority for analysis. The basic helix-loop-helix (bHLH) family of transcription factors is known to be involved in controlling a wide range of systems critical for crop adaptation and quality, including photosynthesis, light signalling, pigment biosynthesis, and seed pod development. Using a hidden Markov model search algorithm, 319 genes with basic helix-loop-helix transcription factor domains were identified within the soybean genome sequence. These were classified with respect to their predicted DNA binding potential, intron/exon structure, and the phylogeny of the bHLH domain. Evidence is presented that the vast majority (281) of these 319 soybean bHLH genes are expressed at the mRNA level. Of these soybean bHLH genes, 67% were found to exist in two or more homeologous copies. This dataset provides a framework for future studies on bHLH gene function in soybean. The challenge for future research remains to define functions for the bHLH factors encoded in the soybean genome, which may allow greater flexibility for genetic selection of growth and environmental adaptation in this widely grown crop.

Optimal Design of Power System Stabilizer Using a Novel Evolutionary Algorithm

2018 ◽  
Vol 7 (3) ◽  
pp. 24-46
Author(s):  
Sourav Paul ◽  
Provas Roy
Keyword(s):  
Optimal Design ◽  
Power System ◽  
Search Algorithm ◽  
Low Frequency ◽  
Optimal Solution ◽  
Power System Stabilizer ◽  
Low Frequency Oscillation ◽  
Large Power ◽  
Wide Range ◽  
System Stabilizer

In this article, an Oppositional Differential search algorithm (ODSA) is comprehensively developed and successfully applied for the optimal design of power system stabilizer (PSS) parameters which are added to the excitation system to dampen low frequency oscillation as it pertains to large power system. The effectiveness of the proposed method is examined and validated on a single machine infinite bus (SMIB) using the Heffron-Phillips model. The most important advantage of the proposed method is as it reaches toward the optimal solution without the optimal tuning of input parameters of the ODSA algorithm. In order to verify the effectiveness, the simulation was made for a wide range of loading conditions. The simulation results of the proposed ODSA are compared with those obtained by other techniques available in the recent literature to demonstrate the feasibility of the proposed algorithm.

Kean Miltos: The Well-Known Iron Oxides of Antiquity

1997 ◽  
Vol 92 ◽  
pp. 359-371 ◽  
Author(s):  
E. Photos-Jones ◽  
A. Cottier ◽  
A. J. Hall ◽  
L. G. Mendoni
Keyword(s):  
Iron Oxides ◽  
Analytical Techniques ◽  
Field Work ◽  
Archaeological Record ◽  
The North ◽  
Naturally Occurring ◽  
Physico Chemical ◽  
Wide Range ◽  
Industrial Mineral

The island of Kea in the North Cyclades was well known in antiquity for its miltos, a naturally occurring red iron oxide valued for its colour and wide range of applications. By combining geological field work, physico-chemical analytical techniques, simulation (heating) experiments as well as simple laboratory tests, this paper describes the study of Kean iron oxides in an attempt to characterize this material which is still largely elusive in the archaeological record. The present work corroborates previous observations about the superior quality of some Kean iron oxides. Furthermore, it puts forward the hypothesis that miltos may have been considered an industrial mineral, and as such may have been used as an umbrella term for a variety of materials including mineralogically distinct purple as well as red iron oxides.

scholarly journals Iron Oxide Contents in Relation to the Colour of Asnawa Soils

2017 ◽  
Vol 1 (1) ◽  
pp. 89-94
Author(s):  
Sherwan Kafoor
Keyword(s):  
Iron Oxide ◽  
Soil Properties ◽  
Iron Oxides ◽  
Soil Samples ◽  
Visual Methods ◽  
Colour Intensity ◽  
Fe Oxide ◽  
Fe Oxides ◽  
New Formula

Asnawa soils contain high amounts of iron oxides. These minerals apply much influence on different soil properties, of which the most observable is colour. The objective of this study was to conclude if colour of soils measured by visual methods can be parameterized to quantify soil Fe oxides. The examined area was divided to three zones (zone A, zone B and zone C) according to their colour intensity. Forty soil samples were examined for their colour and iron oxide contents. Their colour were ranged between 5YR (H) 2.5 (V/C) to 5YR (H) 5/8 (V/C). The average values of free Fe oxide in the soils of the three zones were 52.1%, 36.8% and 15.9% respectively. A new formula was derived to measure colour intensity. A highly significant correlation was found between colour intensity and concentrations of Fe oxides in the examined soils.

scholarly journals Dynamical Models for our Virgocentric Deviation from Hubble Flow

1983 ◽  
Vol 6 ◽  
pp. 751-752
Author(s):  
E. E. Salpeter
Keyword(s):  
Mass Density ◽  
Galaxy Cluster ◽  
Virgo Cluster ◽  
Point Of View ◽  
Model Fit ◽  
Cluster Center ◽  
The Core ◽  
Wide Range ◽  
Range Of Values ◽  
Hubble Flow

Spherically symmetric models for the dynamic development of a galaxy cluster from an initial overdensity have been carried out numerically, without dissipation or 2-body relaxation but with shell crossings included. The deviation ∆V from pure Hubble Flow of the Local Group, due to the retardation effect of the Virgo cluster and supercluster, has been calculated from a number of different models by Hoffman and Salpeter (Astrophys. J. 263, 1982, in press). The results are somewhat surprising if one takes the point of view of (a) insisting that the dynamic model fit the observed dispersion of galaxy systemic velocities in the core of the Virgo cluster, but (b) allowing the mass to light ratio M/L to be an arbitrary (but smoothly varying) function of distance from the Virgo cluster center. Point (a) essentially fixes the mass density and M/L in the core, but (b) still allows a wide range of values for the cosmological density parameters Ω (proportional to the average M/L far from the Virgo cluster). With this point of view ∆V actually decreases with increasing Ω: If M/L is constant, Ω ≈ 0.3 and ∆V ≈ 250 km s–1 (Hoffman, Olson and Salpeter, Ap. J. 242, 861, 1980); for Ω ~ 0.05, ∆V would exceed 350 km s–1; for Ω = 1, AV could be less than 150 km s–1.

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