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3. Deep Convolutions for In-Depth Automated Rock Typing

Author

Baraboshkin, E. E., Ismailova, L. S., Orlov, D. M., Zhukovskaya, E. A., Kalmykov, G. A., Khotylev, O. V., Baraboshkin, E. Yu., and Koroteev, D. A.

Subjects
Computer Science - Computer Vision and Pattern Recognition, Computer Science - Machine Learning, I.4.8, I.4.10
Abstract

The description of rocks is one of the most time-consuming tasks in the everyday work of a geologist, especially when very accurate description is required. We here present a method that reduces the time needed for accurate description of rocks, enabling the geologist to work more efficiently. We describe the application of methods based on color distribution analysis and feature extraction. Then we focus on a new approach, used by us, which is based on convolutional neural networks. We used several well-known neural network architectures (AlexNet, VGG, GoogLeNet, ResNet) and made a comparison of their performance. The precision of the algorithms is up to 95% on the validation set with GoogLeNet architecture. The best of the proposed algorithms can describe 50 m of full-size core in one minute., Comment: 25 pages, 9 figures, 3 tables, submitted to Computers and Geosciences Journal. Keywords: Core Image; Description; Convolutional Neural Networks; Representation; Geology; Lithotypes

Published
2019
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6. Pressure-induced spin pairing transition of Fe$^{3+}$ in oxygen octahedra

Author

Vasiukov, D. M., Dubrovinsky, L., Kupenko, I., Cerantola, V., Aprilis, G., Ismailova, L., Bykova, E., McCammon, C., Prescher, C., Chumakov, A. I., and Dubrovinskaia, N.

Subjects
Condensed Matter - Strongly Correlated Electrons
Abstract

High pressure can provoke spin transitions in transition metal-bearing compounds. These transitions are of high interest not only for fundamental physics and chemistry, but also may have important implications for geochemistry and geophysics of the Earth and planetary interiors. Here we have carried out a comparative study of the pressure-induced spin transition in compounds with trivalent iron, octahedrally coordinated by oxygen. High-pressure single-crystal M\"{o}ssbauer spectroscopy data for FeBO$_3$, Fe$_2$O$_3$ and Fe$_3$(Fe$_{1.766(2)}$Si$_{0.234(2)}$)(SiO$_4$)$_3$ are presented together with detailed analysis of hyperfine parameter behavior. We argue that $\zeta$-Fe$_2$O$_3$ is an intermediate phase in the reconstructive phase transition between $\iota$-Fe$_2$O$_3$ and $\theta$-Fe$_2$O$_3$ and question the proposed perovskite-type structure for $\zeta$-Fe$_2$O$_3$.The structural data show that the spin transition is closely related to the volume of the iron octahedron. The transition starts when volumes reach 8.9-9.3 \AA$^3$, which corresponds to pressures of 45-60 GPa, depending on the compound. Based on phenomenological arguments we conclude that the spin transition can proceed only as a first-order phase transition in magnetically-ordered compounds. An empirical rule for prediction of cooperative behavior at the spin transition is proposed. The instability of iron octahedra, together with strong interactions between them in the vicinity of the critical volume, may trigger a phase transition in the metastable phase. We find that the isomer shift of high spin iron ions depends linearly on the octahedron volume with approximately the same coefficient, independent of the particular compounds and/or oxidation state. For eight-fold coordinated Fe$^{2+}$ we observe a significantly weaker nonlinear volume dependence.

Published
2017

7. Data Domains Modeling Situationally Determined Evaluation

Author

Ismailova, L. Yu., Kosikov, S. V., Wolfengagen, V. E., Kacprzyk, Janusz, Series Editor, Pal, Nikhil R., Advisory Editor, Bello Perez, Rafael, Advisory Editor, Corchado, Emilio S., Advisory Editor, Hagras, Hani, Advisory Editor, Kóczy, László T., Advisory Editor, Kreinovich, Vladik, Advisory Editor, Lin, Chin-Teng, Advisory Editor, Lu, Jie, Advisory Editor, Melin, Patricia, Advisory Editor, Nedjah, Nadia, Advisory Editor, Nguyen, Ngoc Thanh, Advisory Editor, Wang, Jun, Advisory Editor, Arai, Kohei, editor, Kapoor, Supriya, editor, and Bhatia, Rahul, editor

Published
2019
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13. Experimental investigation of FeCO3 (siderite) stability in Earth's lower mantle using XANES spectroscopy

Author

Cerantola, V, Wilke, M, Kantor, I, Ismailova, L, Kupenko, I, Mccammon, C, Pascarelli, S, Dubrovinsky, L, Cerantola V, Wilke M, Kantor I, Ismailova L, Kupenko I, McCammon C, Pascarelli S, Dubrovinsky LS, Cerantola, V, Wilke, M, Kantor, I, Ismailova, L, Kupenko, I, Mccammon, C, Pascarelli, S, Dubrovinsky, L, Cerantola V, Wilke M, Kantor I, Ismailova L, Kupenko I, McCammon C, Pascarelli S, and Dubrovinsky LS

Abstract

We studied FeCO3 using Fe K-edge X-ray absorption near-edge structure (XANES) spectroscopy at pressures up to 54 GPa and temperatures above 2000 K. First-principles calculations of Fe at the K-edge in FeCO3 were performed to support the interpretation of the XANES spectra. The variation of iron absorption edge features with pressure and temperature in FeCO3 matches well with recently reported observations on FeCO3 at extreme conditions, and provides new insight into the stability of Fe-carbonates in Earth's mantle. Here we show that at conditions of the mid-lower mantle, ~50 GPa and ~2200 K, FeCO3 melts and partially decomposes to high-pressure Fe3O4. Carbon (diamond) and oxygen are also inferred products of the reaction. We constrained the thermodynamic phase boundary between crystalline FeCO3 and melt to be at 51(1) GPa and ~1850 K. We observe that at 54(1) GPa, temperature-induced spin crossover of Fe2+ takes place from low to high spin such that at 1735(100) K, all iron in FeCO3 is in the high-spin state. A comparison between experiment and theory provides a more detailed understanding of FeCO3 decomposition observed in X-ray absorption spectra and helps to explain spectral changes due to pressure-induced spin crossover in FeCO3 at ambient temperature.

Published
2019

16. The high-pressure behavior of spherocobaltite (CoCO3): a single crystal Raman spectroscopy and XRD study

Author

Chariton, S, Cerantola, V, Ismailova, L, Bykova, E, Bykov, M, Kupenko, I, Mccammon, C, Dubrovinsky, L, Chariton S, Cerantola V, Ismailova L, Bykova E, Bykov M, Kupenko I, McCammon C, Dubrovinsky L, Chariton, S, Cerantola, V, Ismailova, L, Bykova, E, Bykov, M, Kupenko, I, Mccammon, C, Dubrovinsky, L, Chariton S, Cerantola V, Ismailova L, Bykova E, Bykov M, Kupenko I, McCammon C, and Dubrovinsky L

Abstract

Magnesite (MgCO3), calcite (CaCO3), dolomite [(Ca, Mg)CO3], and siderite (FeCO3) are among the best-studied carbonate minerals at high pressures and temperatures. Although they all exhibit the calcite-type structure (R 3 ̄ c) at ambient conditions, they display very different behavior at mantle pressures. To broaden the knowledge of the high-pressure crystal chemistry of carbonates, we studied spherocobaltite (CoCO3), which contains Co2+ with cation radius in between those of Ca2+ and Mg2+ in calcite and magnesite, respectively. We synthesized single crystals of pure spherocobaltite and studied them using Raman spectroscopy and X-ray diffraction in diamond anvil cells at pressures to over 55 GPa. Based on single crystal diffraction data, we found that the bulk modulus of spherocobaltite is 128 (2) GPa and K′ = 4.28 (17). CoCO3 is stable in the calcite-type structure up to at least 56 GPa and 1200 K. At 57 GPa and after laser heating above 2000 K, CoCO3 partially decomposes and forms CoO. In comparison to previously studied carbonates, our results suggest that at lower mantle conditions carbonates can be stable in the calcite-type structure if the radius of the incorporated cation(s) is equal or smaller than that of Co2+ (i.e., 0.745 Å).

Published
2018

17. Sound velocities of skiagite-iron-majorite solid solution to 56 GPa probed by nuclear inelastic scattering

Author

Vasiukov, D, Ismailova, L, Kupenko, I, Cerantola, V, Sinmyo, R, Glazyrin, K, Mccammon, C, Chumakov, A, Dubrovinsky, L, Dubrovinskaia, N, Vasiukov DM, Ismailova L, Kupenko I, Cerantola V, Sinmyo R, Glazyrin K, McCammon C, Chumakov AI, Dubrovinsky L, Dubrovinskaia N, Vasiukov, D, Ismailova, L, Kupenko, I, Cerantola, V, Sinmyo, R, Glazyrin, K, Mccammon, C, Chumakov, A, Dubrovinsky, L, Dubrovinskaia, N, Vasiukov DM, Ismailova L, Kupenko I, Cerantola V, Sinmyo R, Glazyrin K, McCammon C, Chumakov AI, Dubrovinsky L, and Dubrovinskaia N

Abstract

High-pressure experimental data on sound velocities of garnets are used for interpretation of seismological data related to the Earth’s upper mantle and the mantle transition zone. We have carried out a Nuclear Inelastic Scattering study of iron-silicate garnet with skiagite (77 mol%)–iron–majorite composition in a diamond anvil cell up to 56 GPa at room temperature. The determined sound velocities are considerably lower than sound velocities of a number of silicate garnet end-members, such as grossular, pyrope, Mg–majorite, andradite, and almandine. The obtained sound velocities have the following pressure dependencies: Vp [km/s] = 7.43(9) + 0.039(4) × P [GPa] and Vs [km/s] = 3.56(12) + 0.012(6) × P [GPa]. We estimated sound velocities of pure skiagite and khoharite, and conclude that the presence of the iron–majorite component in skiagite strongly decreases Vs. We analysed the influence of Fe3+ on sound velocities of garnet solid solution relevant to the mantle transition zone and consider that it may reduce sound velocities up to 1% relative to compositions with only Fe2+ in the cubic site.

Published
2018

19. Stability of iron-bearing carbonates in the deep Earth's interior

Author

Cerantola, V, Bykova, E, Kupenko, I, Merlini, M, Ismailova, L, Mccammon, C, Bykov, M, Chumakov, A, Petitgirard, S, Kantor, I, Svitlyk, V, Jacobs, J, Hanfland, M, Mezouar, M, Prescher, C, Ruffer, R, Prakapenka, V, Dubrovinsky, L, Cerantola V, Bykova E, Kupenko I, Merlini M, Ismailova L, McCammon C, Bykov M, Chumakov AI, Petitgirard S, Kantor I, Svitlyk V, Jacobs J, Hanfland M, Mezouar M, Prescher C, Ruffer R, Prakapenka VB, Dubrovinsky L, Cerantola, V, Bykova, E, Kupenko, I, Merlini, M, Ismailova, L, Mccammon, C, Bykov, M, Chumakov, A, Petitgirard, S, Kantor, I, Svitlyk, V, Jacobs, J, Hanfland, M, Mezouar, M, Prescher, C, Ruffer, R, Prakapenka, V, Dubrovinsky, L, Cerantola V, Bykova E, Kupenko I, Merlini M, Ismailova L, McCammon C, Bykov M, Chumakov AI, Petitgirard S, Kantor I, Svitlyk V, Jacobs J, Hanfland M, Mezouar M, Prescher C, Ruffer R, Prakapenka VB, and Dubrovinsky L

Abstract

The presence of carbonates in inclusions in diamonds coming from depths exceeding 670 km are obvious evidence that carbonates exist in the Earth's lower mantle. However, their range of stability, crystal structures and the thermodynamic conditions of the decarbonation processes remain poorly constrained. Here we investigate the behaviour of pure iron carbonate at pressures over 100 GPa and temperatures over 2,500 K using single-crystal X-ray diffraction and Mössbauer spectroscopy in laser-heated diamond anvil cells. On heating to temperatures of the Earth's geotherm at pressures to ∼50 GPa FeCO3 partially dissociates to form various iron oxides. At higher pressures FeCO3 forms two new structures - tetrairon(III) orthocarbonate Fe4 3+C3O12, and diiron(II) diiron(III) tetracarbonate Fe2 2+Fe2 3+C4O13, both phases containing CO4 tetrahedra. Fe4C4O13 is stable at conditions along the entire geotherm to depths of at least 2,500 km, thus demonstrating that self-oxidation-reduction reactions can preserve carbonates in the Earth's lower mantle.

Published
2017

20. Effect of composition on compressibility of skiagite-Fe-majorite garnet

Author

Ismailova, L, Bykov, M, Bykova, E, Bobrov, A, Kupenko, I, Cerantola, V, Vasiukov, D, Dubrovinskaia, N, Mccammon, C, Hanfland, M, Glazyrin, K, Liermann, H, Chumakov, A, Dubrovinsky, L, Ismailova L, Bykov M, Bykova E, Bobrov A, Kupenko I, Cerantola V, Vasiukov D, Dubrovinskaia N, McCammon C, Hanfland M, Glazyrin K, Liermann HP, Chumakov A, Dubrovinsky L, Ismailova, L, Bykov, M, Bykova, E, Bobrov, A, Kupenko, I, Cerantola, V, Vasiukov, D, Dubrovinskaia, N, Mccammon, C, Hanfland, M, Glazyrin, K, Liermann, H, Chumakov, A, Dubrovinsky, L, Ismailova L, Bykov M, Bykova E, Bobrov A, Kupenko I, Cerantola V, Vasiukov D, Dubrovinskaia N, McCammon C, Hanfland M, Glazyrin K, Liermann HP, Chumakov A, and Dubrovinsky L

Abstract

Skiagite-Fe-majorite garnets were synthesized using a multianvil apparatus at 7.5-9.5 GPa and 1400-1600 K. Single-crystal X-ray diffraction at ambient conditions revealed that synthesized garnets contain 23 to 76% of an Fe-majorite component. We found that the substitution of Fe2+ and Si4+ for Fe3+ in the octahedral site decreases the unit-cell volume of garnet at ambient conditions. Analysis of single-crystal X-ray diffraction data collected on compression up to 90 GPa of garnets with different compositions reveals that with increasing majorite component the bulk modulus increases from 159(1) to 172(1) GPa. Our results and literature data unambiguously demonstrate that the total iron content and the Fe3+/Fe2+ ratio in (Mg, Fe)-majorites have a large influence on their elasticity. At pressures between 50 and 60 GPa we observed a significant deviation from a monotonic dependence of the molar volumes of skiagite-Fe-majorite garnet with pressure, and over a small pressure interval the volume dropped by about 3%. By combining results from single-crystal X-ray diffraction and high-pressure synchrotron Mössbauer source spectroscopy we demonstrate that these changes in the compressional behavior are associated with changes of the electronic state of Fe in the octahedral site.

Published
2017

21. Stability of Fe,Al-bearing bridgmanite in the lower mantle and synthesis of pure Fe-bridgmanite

Author

Ismailova, L, Bykova, E, Bykov, M, Cerantola, V, Mccammon, C, Ballaran, T, Bobrov, A, Sinmyo, R, Dubrovinskaia, N, Glazyrin, K, Liermann, H, Kupenko, I, Hanfland, M, Prescher, C, Prakapenka, V, Svitlyk, V, Dubrovinsky, L, Ismailova L, Bykova E, Bykov M, Cerantola V, McCammon C, Ballaran TB, Bobrov A, Sinmyo R, Dubrovinskaia N, Glazyrin K, Liermann HP, Kupenko I, Hanfland M, Prescher C, Prakapenka V, Svitlyk V, Dubrovinsky L, Ismailova, L, Bykova, E, Bykov, M, Cerantola, V, Mccammon, C, Ballaran, T, Bobrov, A, Sinmyo, R, Dubrovinskaia, N, Glazyrin, K, Liermann, H, Kupenko, I, Hanfland, M, Prescher, C, Prakapenka, V, Svitlyk, V, Dubrovinsky, L, Ismailova L, Bykova E, Bykov M, Cerantola V, McCammon C, Ballaran TB, Bobrov A, Sinmyo R, Dubrovinskaia N, Glazyrin K, Liermann HP, Kupenko I, Hanfland M, Prescher C, Prakapenka V, Svitlyk V, and Dubrovinsky L

Abstract

The physical and chemical properties of Earth’s mantle, as well as its dynamics and evolution, heavily depend on the phase composition of the region. On the basis of experiments in laser-heated diamond anvil cells, we demonstrate that Fe,Al-bearing bridgmanite (magnesium silicate perovskite) is stable to pressures over 120 GPa and temperatures above 3000 K. Ferric iron stabilizes Fe-rich bridgmanite such that we were able to synthesize pure iron bridgmanite at pressures between ~45 and 110 GPa. The compressibility of ferric iron–bearing bridgmanite is significantly different from any known bridgmanite, which has direct implications for the interpretation of seismic tomography data.

Published
2016

24. High-pressure synthesis of skiagite-majorite garnet and investigation of its crystal structure

Author

Ismailova, L, Bobrov, A, Bykov, M, Bykova, E, Cerantola, V, Kantor, I, Kupenko, I, Mccammon, C, Dyadkin, V, Chernyshov, D, Pascarelli, S, Chumakov, A, Dubrovinskaia, N, Dubrovinisky, L, Ismailova L, Bobrov A, Bykov M, Bykova E, Cerantola V, Kantor I, Kupenko I, McCammon C, Dyadkin V, Chernyshov D, Pascarelli S, Chumakov A, Dubrovinskaia N, Dubrovinisky L, Ismailova, L, Bobrov, A, Bykov, M, Bykova, E, Cerantola, V, Kantor, I, Kupenko, I, Mccammon, C, Dyadkin, V, Chernyshov, D, Pascarelli, S, Chumakov, A, Dubrovinskaia, N, Dubrovinisky, L, Ismailova L, Bobrov A, Bykov M, Bykova E, Cerantola V, Kantor I, Kupenko I, McCammon C, Dyadkin V, Chernyshov D, Pascarelli S, Chumakov A, Dubrovinskaia N, and Dubrovinisky L

Abstract

Skiagite-rich garnet was synthesized as single crystals at 9.5 GPa and 1100 °C using a multi-anvil apparatus. The crystal structure [cubic, space group Ia3d, a = 11.7511(2) Å, V = 1622.69(5) Å3, Dcalc = 4.4931 g/cm3] was investigated using single-crystal synchrotron X-ray diffraction. Synchrotron Mössbauer source spectroscopy revealed that Fe2+ and Fe3+ predominantly occupy dodecahedral (X) and octahedral (Y) sites, respectively, as expected for the garnet structure, and confirmed independently using nuclear forward scattering. Single-crystal X-ray diffraction suggests the structural formula of the skiagite-rich garnet to be Fe32+(Fe2+0.234(2)Fe3+1.532(1)Si4+0.234(2))(SiO4)3, in agreement with electron microprobe chemical analysis. The formula is consistent with X-ray absorption near-edge structure spectra. The occurrence of Si and Fe2+ in the octahedral Y-site indicates the synthesized garnet to be a solid solution of end-member skiagite with ∼23 mol% of the Fe-majorite end-member Fe32+(Fe2+Si4+)(SiO4)3.

Published
2015

35. The high-pressure behavior of spherocobaltite (CoCO3): a single crystal Raman spectroscopy and XRD study

Author

Valerio Cerantola, Elena Bykova, Stella Chariton, Catherine McCammon, Maxim Bykov, Leyla Ismailova, Ilya Kupenko, Leonid Dubrovinsky, Chariton, S, Cerantola, V, Ismailova, L, Bykova, E, Bykov, M, Kupenko, I, Mccammon, C, and Dubrovinsky, L

Subjects
Spherocobaltite, CoCO3, 010504 meteorology & atmospheric sciences, Crystal chemistry, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, Diamond anvil cell, Transition metal carbonate, chemistry.chemical_compound, symbols.namesake, Geochemistry and Petrology, General Materials Science, 0105 earth and related environmental sciences, Calcite, Bulk modulus, X-ray diffraction, High pressure, Crystallography, chemistry, Raman spectroscopy, symbols, engineering, Single crystal, Magnesite
Abstract

Magnesite (MgCO3), calcite (CaCO3), dolomite [(Ca, Mg)CO3], and siderite (FeCO3) are among the best-studied carbonate minerals at high pressures and temperatures. Although they all exhibit the calcite-type structure ( $${\text{R}}\bar{3}{\text{c}}$$ ) at ambient conditions, they display very different behavior at mantle pressures. To broaden the knowledge of the high-pressure crystal chemistry of carbonates, we studied spherocobaltite (CoCO3), which contains Co2+ with cation radius in between those of Ca2+ and Mg2+ in calcite and magnesite, respectively. We synthesized single crystals of pure spherocobaltite and studied them using Raman spectroscopy and X-ray diffraction in diamond anvil cells at pressures to over 55 GPa. Based on single crystal diffraction data, we found that the bulk modulus of spherocobaltite is 128 (2) GPa and K′ = 4.28 (17). CoCO3 is stable in the calcite-type structure up to at least 56 GPa and 1200 K. At 57 GPa and after laser heating above 2000 K, CoCO3 partially decomposes and forms CoO. In comparison to previously studied carbonates, our results suggest that at lower mantle conditions carbonates can be stable in the calcite-type structure if the radius of the incorporated cation(s) is equal or smaller than that of Co2+ (i.e., 0.745 A).

Published
2017
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36. Experimental investigation of FeCO3 (siderite) stability in Earth's lower mantle using XANES spectroscopy

Author

Valerio Cerantola, Catherine McCammon, Sakura Pascarelli, Leonid Dubrovinsky, Leyla Ismailova, Max Wilke, Ilya Kupenko, Innokenty Kantor, Cerantola, V, Wilke, M, Kantor, I, Ismailova, L, Kupenko, I, Mccammon, C, Pascarelli, S, and Dubrovinsky, L

Subjects
XANES Spectroscopy, Materials science, decomposition, melting, 010504 meteorology & atmospheric sciences, Earth in Five Reaction, A Deep Carbon Perspective, Analytical chemistry, Spin transition, siderite, spin transition, 010502 geochemistry & geophysics, 01 natural sciences, Decomposition, Stability (probability), Siderite, chemistry.chemical_compound, Geophysics, Deep carbon cycle, chemistry, Geochemistry and Petrology, ddc:550, Institut für Geowissenschaften, Earth (classical element), 0105 earth and related environmental sciences
Abstract

We studied FeCO3 using Fe K-edge X-ray absorption near-edge structure (XANES) spectroscopy at pressures up to 54 GPa and temperatures above 2000 K. First-principles calculations of Fe at the K-edge in FeCO3 were performed to support the interpretation of the XANES spectra. The variation of iron absorption edge features with pressure and temperature in FeCO3 matches well with recently reported observations on FeCO3 at extreme conditions, and provides new insight into the stability of Fe-carbonates in Earth's mantle. Here we show that at conditions of the mid-lower mantle, ~50 GPa and ~2200 K, FeCO3 melts and partially decomposes to high-pressure Fe3O4. Carbon (diamond) and oxygen are also inferred products of the reaction. We constrained the thermodynamic phase boundary between crystalline FeCO3 and melt to be at 51(1) GPa and ~1850 K. We observe that at 54(1) GPa, temperature-induced spin crossover of Fe2+ takes place from low to high spin such that at 1735(100) K, all iron in FeCO3 is in the high-spin state. A comparison between experiment and theory provides a more detailed understanding of FeCO3 decomposition observed in X-ray absorption spectra and helps to explain spectral changes due to pressure-induced spin crossover in FeCO3 at ambient temperature.

Published
2019

37. Sound velocities of skiagite-iron-majorite solid solution to 56 GPa probed by nuclear inelastic scattering

Author

Leonid Dubrovinsky, Ryosuke Sinmyo, Valerio Cerantola, Leyla Ismailova, Ilya Kupenko, Catherine McCammon, Konstantin Glazyrin, Alexander Chumakov, Denis M. Vasiukov, Natalia Dubrovinskaia, Vasiukov, D, Ismailova, L, Kupenko, I, Cerantola, V, Sinmyo, R, Glazyrin, K, Mccammon, C, Chumakov, A, Dubrovinsky, L, and Dubrovinskaia, N

Subjects
Majorite, 010504 meteorology & atmospheric sciences, Mantle transition zone, Inelastic scattering, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, Skiagite, Almandine, Geochemistry and Petrology, Sound velocitie, Transition zone, Khoharite, General Materials Science, 0105 earth and related environmental sciences, Grossular, biology, Chemistry, Garnet, biology.organism_classification, Pyrope, Nuclear inelastic scattering, Andradite, visual_art, visual_art.visual_art_medium, engineering, Atomic physics, Solid solution
Abstract

High-pressure experimental data on sound velocities of garnets are used for interpretation of seismological data related to the Earth’s upper mantle and the mantle transition zone. We have carried out a Nuclear Inelastic Scattering study of iron-silicate garnet with skiagite (77 mol%)–iron–majorite composition in a diamond anvil cell up to 56 GPa at room temperature. The determined sound velocities are considerably lower than sound velocities of a number of silicate garnet end-members, such as grossular, pyrope, Mg–majorite, andradite, and almandine. The obtained sound velocities have the following pressure dependencies: V p [km/s] = 7.43(9) + 0.039(4) × P [GPa] and V s [km/s] = 3.56(12) + 0.012(6) × P [GPa]. We estimated sound velocities of pure skiagite and khoharite, and conclude that the presence of the iron–majorite component in skiagite strongly decreases V s . We analysed the influence of Fe3+ on sound velocities of garnet solid solution relevant to the mantle transition zone and consider that it may reduce sound velocities up to 1% relative to compositions with only Fe2+ in the cubic site.

Published
2018

38. Effect of composition on compressibility of skiagite-Fe-majorite garnet

Author

Elena Bykova, Leonid Dubrovinsky, Alexander Chumakov, Maxim Bykov, Hanns-Peter Liermann, Konstantin Glazyrin, Leyla Ismailova, Catherine McCammon, Denis M. Vasiukov, Ilya Kupenko, Michael Hanfland, Natalia Dubrovinskaia, Andrey V. Bobrov, Valerio Cerantola, Ismailova, L, Bykov, M, Bykova, E, Bobrov, A, Kupenko, I, Cerantola, V, Vasiukov, D, Dubrovinskaia, N, Mccammon, C, Hanfland, M, Glazyrin, K, Liermann, H, Chumakov, A, and Dubrovinsky, L

Subjects
Diffraction, Majorite, Bulk modulus, Materials science, 010504 meteorology & atmospheric sciences, Mössbauer spectroscopy, Analytical chemistry, Mineralogy, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, upper mantle, Geophysics, Octahedron, Geochemistry and Petrology, Skiagite-majorite garnet, transition zone, engineering, Compressibility, single-crystal X-ray diffraction, Elasticity (economics), Spectroscopy, equation of state, 0105 earth and related environmental sciences
Abstract

Skiagite-Fe-majorite garnets were synthesized using a multianvil apparatus at 7.5–9.5 GPa and 1400–1600 K. Single-crystal X-ray diffraction at ambient conditions revealed that synthesized garnets contain 23 to 76% of an Fe-majorite component. We found that the substitution of Fe 2+ and Si 4+ for Fe 3+ in the octahedral site decreases the unit-cell volume of garnet at ambient conditions. Analysis of single-crystal X-ray diffraction data collected on compression up to 90 GPa of garnets with different compositions reveals that with increasing majorite component the bulk modulus increases from 159(1) to 172(1) GPa. Our results and literature data unambiguously demonstrate that the total iron content and the Fe 3+ /Fe 2+ ratio in (Mg,Fe)-majorites have a large influence on their elasticity. At pressures between 50 and 60 GPa we observed a significant deviation from a monotonic dependence of the molar volumes of skiagite-Fe-majorite garnet with pressure, and over a small pressure interval the volume dropped by about 3%. By combining results from single-crystal X-ray diffraction and high-pressure synchrotron Mossbauer source spectroscopy we demonstrate that these changes in the compressional behavior are associated with changes of the electronic state of Fe in the octahedral site.

Published
2017

39. Stability of iron-bearing carbonates in the deep Earth's interior

Author

Volodymyr Svitlyk, Jeroen Jacobs, Sylvain Petitgirard, Michael Hanfland, Clemens Prescher, Catherine McCammon, Mohamed Mezouar, Marco Merlini, Leonid Dubrovinsky, Maxim Bykov, Valerio Cerantola, Ilya Kupenko, Innokenty Kantor, Elena Bykova, A. I. Chumakov, Leyla Ismailova, Rudolf Rüffer, Vitali B. Prakapenka, Univ Bayreuth, Bayer Geoinst, D-95440 Bayreuth, Germany, European Synchrotron Radiation Facility (ESRF), DESY, Extreme Condit Beamline P02 2, Notkestr 85, D-22607 Hamburg, Germany, Univ Munster, Inst Mineral, Corrensstr 24, D-48149 Munster, Germany, Univ Milan, Dipartimento Sci Terra, Via Botticelli 23, I-20133 Milan, Italy, Skolkovo Innovat Ctr, Skolkovo Inst Sci & Technol, Ctr Hydrocarbon Recovery, Moscow 143026, Russia, Natl Univ Sci & Technol MSIS, Mat Modeling & Dev Lab, Moscow 119049, Russia, MAX IV Lab, Fotongatan 2, S-22594 Lund, Sweden, Univ Cologne, Inst Geol & Mineral, Greinstr 4-6, D-50939 Cologne, Germany, University of Chicago, Cerantola, V, Bykova, E, Kupenko, I, Merlini, M, Ismailova, L, Mccammon, C, Bykov, M, Chumakov, A, Petitgirard, S, Kantor, I, Svitlyk, V, Jacobs, J, Hanfland, M, Mezouar, M, Prescher, C, Ruffer, R, Prakapenka, V, and Dubrovinsky, L

Subjects
Materials science, 010504 meteorology & atmospheric sciences, XRD, Science, General Physics and Astronomy, Mineralogy, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, reaction, Crystal structure, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, General Biochemistry, Genetics and Molecular Biology, Diamond anvil cell, Mantle (geology), Article, high temperature, Mössbauer spectroscopy, synchrotron, 14. Life underwater, Geothermal gradient, 0105 earth and related environmental sciences, Multidisciplinary, Iron carbonate, siderite, Diamond, General Chemistry, laser heating, phase diagram, high pressure, diamond anvil cell, 13. Climate action, phase transition, redox, engineering, ddc:500, tetracarbonate
Abstract

The presence of carbonates in inclusions in diamonds coming from depths exceeding 670 km are obvious evidence that carbonates exist in the Earth’s lower mantle. However, their range of stability, crystal structures and the thermodynamic conditions of the decarbonation processes remain poorly constrained. Here we investigate the behaviour of pure iron carbonate at pressures over 100 GPa and temperatures over 2,500 K using single-crystal X-ray diffraction and Mössbauer spectroscopy in laser-heated diamond anvil cells. On heating to temperatures of the Earth’s geotherm at pressures to ∼50 GPa FeCO3 partially dissociates to form various iron oxides. At higher pressures FeCO3 forms two new structures—tetrairon(III) orthocarbonate Fe43+C3O12, and diiron(II) diiron(III) tetracarbonate Fe22+Fe23+C4O13, both phases containing CO4 tetrahedra. Fe4C4O13 is stable at conditions along the entire geotherm to depths of at least 2,500 km, thus demonstrating that self-oxidation-reduction reactions can preserve carbonates in the Earth’s lower mantle., Carbonates are shown to exist in the lower mantle as seen in diamond inclusions, but thermodynamic constraints are poorly understood. Here, the authors synthesise two new iron carbonate compounds and find that self-oxidation-reduction reactions can preserve carbonates in the mantle.

Published
2017
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40. Stability of Fe,Al-bearing bridgmanite in the lower mantle and synthesis of pure Fe-bridgmanite

Author

Leyla Ismailova, Elena Bykova, Clemens Prescher, Maxim Bykov, Ryosuke Sinmyo, Konstantin Glazyrin, Ilya Kupenko, Hanns-Peter Liermann, Michael Hanfland, Catherine McCammon, Leonid Dubrovinsky, Volodymyr Svitlyk, Tiziana Boffa Ballaran, Natalia Dubrovinskaia, Andrei Bobrov, Valerio Cerantola, Vitali B. Prakapenka, Ismailova, L, Bykova, E, Bykov, M, Cerantola, V, Mccammon, C, Ballaran, T, Bobrov, A, Sinmyo, R, Dubrovinskaia, N, Glazyrin, K, Liermann, H, Kupenko, I, Hanfland, M, Prescher, C, Prakapenka, V, Svitlyk, V, and Dubrovinsky, L

Subjects
Materials science, single crystal x-ray diffraction, 010504 meteorology & atmospheric sciences, XRD, Earth, Planet, Iron, Silicate perovskite, Bridgmanite, Mineralogy, chemistry.chemical_element, Thermodynamics, 010502 geochemistry & geophysics, 01 natural sciences, Mantle (geology), Diamond anvil cell, X-Ray Diffraction, Aluminium, Magnesium Silicates, medicine, Pressure, Research Articles, 0105 earth and related environmental sciences, Titanium, Multidisciplinary, Mössbauer spectroscopy, Magnesium silicate, Temperature, SciAdv r-articles, Oxides, Calcium Compounds, laser heating, high pressure, Geophysics, lower mantle, chemistry, diamond anvil cell, X-ray crystallography, Ferric, ddc:500, medicine.drug, Aluminum, Research Article
Abstract

A study of Fe,Al-bearing bridgmanite in Earth‘s mantle and synthesis of pure Fe-bridgmanite with anomalously low compressibility., The physical and chemical properties of Earth’s mantle, as well as its dynamics and evolution, heavily depend on the phase composition of the region. On the basis of experiments in laser-heated diamond anvil cells, we demonstrate that Fe,Al-bearing bridgmanite (magnesium silicate perovskite) is stable to pressures over 120 GPa and temperatures above 3000 K. Ferric iron stabilizes Fe-rich bridgmanite such that we were able to synthesize pure iron bridgmanite at pressures between ~45 and 110 GPa. The compressibility of ferric iron–bearing bridgmanite is significantly different from any known bridgmanite, which has direct implications for the interpretation of seismic tomography data.

Published
2016
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41. High-pressure synthesis of skiagite-majorite garnet and investigation of its crystal structure

Author

Leyla Ismailova, Valerio Cerantola, Vadim Dyadkin, Andrey V. Bobrov, Sakura Pascarelli, Elena Bykova, Maxim Bykov, Catherine McCammon, Natalia Dubrovinskaia, Aleksandr I. Chumakov, Ilya Kupenko, Leonid Dubrovinsky, Innokenty Kantor, Dmitry Chernyshov, Ismailova, L, Bobrov, A, Bykov, M, Bykova, E, Cerantola, V, Kantor, I, Kupenko, I, Mccammon, C, Dyadkin, V, Chernyshov, D, Pascarelli, S, Chumakov, A, Dubrovinskaia, N, and Dubrovinisky, L

Subjects
Majorite, Materials science, Mössbauer spectroscopy, garnet, Structural formula, Electron microprobe, Crystal structure, engineering.material, majorite, Skiagite, XANES, Crystallography, Geophysics, Geochemistry and Petrology, engineering, single-crystal X-ray diffraction, Spectroscopy, nuclear forward scattering, Solid solution
Abstract

Skiagite-rich garnet was synthesized as single crystals at 9.5 GPa and 1100 °C using a multi-anvil apparatus. The crystal structure [cubic, space group Ia 3 d , a = 11.7511(2) A, V = 1622.69(5) A3, D calc = 4.4931 g/cm3] was investigated using single-crystal synchrotron X-ray diffraction. Synchrotron Mossbauer source spectroscopy revealed that Fe2+ and Fe3+ predominantly occupy dodecahedral (X) and octahedral (Y) sites, respectively, as expected for the garnet structure, and confirmed independently using nuclear forward scattering. Single-crystal X-ray diffraction suggests the structural formula of the skiagite-rich garnet to be Fe32+(Fe2+0.234(2)Fe3+1.532(1)Si4+0.234(2))(SiO4)3, in agreement with electron microprobe chemical analysis. The formula is consistent with X-ray absorption near-edge structure spectra. The occurrence of Si and Fe2+ in the octahedral Y-site indicates the synthesized garnet to be a solid solution of end-member skiagite with ~23 mol% of the Fe-majorite end-member Fe32+(Fe2+Si4+)(SiO4)3.

Published
2015

43. Stability of iron-bearing carbonates in the deep Earth's interior.

Author

Cerantola V, Bykova E, Kupenko I, Merlini M, Ismailova L, McCammon C, Bykov M, Chumakov AI, Petitgirard S, Kantor I, Svitlyk V, Jacobs J, Hanfland M, Mezouar M, Prescher C, Rüffer R, Prakapenka VB, and Dubrovinsky L

Abstract

The presence of carbonates in inclusions in diamonds coming from depths exceeding 670 km are obvious evidence that carbonates exist in the Earth's lower mantle. However, their range of stability, crystal structures and the thermodynamic conditions of the decarbonation processes remain poorly constrained. Here we investigate the behaviour of pure iron carbonate at pressures over 100 GPa and temperatures over 2,500 K using single-crystal X-ray diffraction and Mössbauer spectroscopy in laser-heated diamond anvil cells. On heating to temperatures of the Earth's geotherm at pressures to ∼50 GPa FeCO 3 partially dissociates to form various iron oxides. At higher pressures FeCO 3 forms two new structures-tetrairon(III) orthocarbonate Fe 4 3+ C 3 O 12 , and diiron(II) diiron(III) tetracarbonate Fe 2 2+ Fe 2 3+ C 4 O 13 , both phases containing CO 4 tetrahedra. Fe 4 C 4 O 13 is stable at conditions along the entire geotherm to depths of at least 2,500 km, thus demonstrating that self-oxidation-reduction reactions can preserve carbonates in the Earth's lower mantle.

Published
2017
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44. Discovery of Fe7O9: a new iron oxide with a complex monoclinic structure.

Author

Sinmyo R, Bykova E, Ovsyannikov SV, McCammon C, Kupenko I, Ismailova L, and Dubrovinsky L

Abstract

Iron oxides are fundamentally important compounds for basic and applied sciences as well as in numerous industrial applications. In this work we report the synthesis and investigation of a new binary iron oxide with the hitherto unknown stoichiometry of Fe7O9. This new oxide was synthesized at high-pressure high-temperature (HP-HT) conditions, and its black single crystals were successfully recovered at ambient conditions. By means of single crystal X-ray diffraction we determined that Fe7O9 adopts a monoclinic C2/m lattice with the most distorted crystal structure among the binary iron oxides known to date. The synthesis of Fe7O9 opens a new portal to exotic iron-rich (M,Fe)7O9 oxides with unusual stoichiometry and distorted crystal structures. Moreover, the crystal structure and phase relations of such new iron oxide groups may provide new insight into the cycling of volatiles in the Earth's interior.

Published
2016
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45. [Spatial structure of isoleucine pentapeptides Glu-Phe-Leu-Arg-Ile-NH2 and Pro-Phe-Tyr-Arg-Ile-NH2].

Author

Ismailova LI, Akhmedov NA, and Abbasly RM

Subjects
Protein Conformation, Isoleucine chemistry, Models, Molecular, Oligopeptides chemistry
Abstract

The spatial structure of two cardioactive isoleucine pentapeptides Glu-Phe-Leu-Arg-Ile-NH2 (I) and Pro-Phe-Tyr-Arg-Ile-NH2 (II) have been investigated using the theoretical conformational analysis. The low-energy conformations of these molecules were found, the values of dihedral angles of the backbone and side chains of the amino acid residues constituting these peptides were determined, and the energies of intra- and interresidual interactions were estimated. It was revealed that the spatial structure of molecule I can exist as five and that of molecule II as seven stable backbone forms.

Published
2008

46. [Spatial structure of the cardioactive octapeptide].

Author

Ismailova LI, Abbasly RM, and Akhmedov NA

Subjects
Protein Conformation, Thermodynamics, Models, Molecular, Oligopeptides chemistry
Abstract

The spatial structure of the cardioactive octapeptide Pro1-Gln2-Asp3-Pro4-Phe5-Leu6-Arg7-Ile8-NH2 was investigated using the theoretical conformational analysis. The low-energy conformations of the octapeptide molecule were found, the values of dihedral angles of the backbone and side chains of the amino acid residues constituting the peptide were determined, and the energies of intra-and interresidual interactions were estimated. It was shown that the spatial structure of this molecule represent six stable low-energy forms of the main chain.

Published
2007

47. [Influence of (460 MHz) electromagnetic fields on the induced lipid peroxidation in the structures of visual analyzer and hypothalamus in experimental animals].

Author

Musaev AV, Ismailova LF, and Gadzhiev AM

Subjects
Animals, Hypothalamus metabolism, Lens, Crystalline metabolism, Lens, Crystalline radiation effects, Rats, Retina metabolism, Retina radiation effects, Visual Cortex metabolism, Electromagnetic Fields, Hypothalamus radiation effects, Lipid Peroxidation radiation effects, Radio Waves, Visual Cortex radiation effects
Abstract

Changes in the intensity of ascorbate- and NADPN2-dependent induced lipid peroxidation (LPO) were studied in exposure of the visual analyzer and hypothalamus of 3- and 12-month-old rats to radiation with microwaves of high and low intensity. The exposure to microwaves of high intensity stimulated basal LPO but suppressed activity of LPO-inducing systems. This suggests disturbances in the activity of different sources of active oxygen forms. Microwaves of low intensity activated systems of induced LPO. This is accompanied with synchronous activity of the antioxidant defense system maintaining a normal oxidation-reduction balance of the cell. The conclusion is that, depending on their intensity, microwaves can be either beneficial to health or be a factor of oxidative stress.

Published
2005

48. [Spatial structure of myelopeptides: I. Conformational analysis of MP-1, MP-2, and MP-3].

Author

Akhmetov NA, Ismailova LI, Abbasly RM, Akhmedov NF, and Godzhaev NM

Subjects
Amino Acid Sequence, Animals, Humans, Molecular Conformation, Thermodynamics, Models, Molecular, Oligopeptides chemistry
Abstract

Theoretical conformational analysis was used to study the spatial structure and conformational properties of myelopeptides, bone-marrow peptide mediators. The low-energy conformations of three hexapeptides MP-1 (Phe-Leu-Gly-Phe-Pro-Thr), MP-2 (Leu-Val-Val-Tyr-Pro-Trp), and MP-3 (Leu-Val-Cys-Tyr-Pro-Gln) were found, the values of dihedral angles of the backbone and side chains of the amino acid residues constituting these peptides were determined, and the energies of intra- and interresidual interactions were estimated.

Published
2005

49. [Pro- and antioxidant effect of electromagnetic fields of extremely high frequency (460 MHz) on brain tissues in experiment].

Author

Musaev AV, Ismailova LF, Shabanova AB, Magerramov AA, Iusifov EIu, and Gadzhiev AM

Subjects
Animals, Glutathione Reductase metabolism, Hypothalamus enzymology, Hypothalamus metabolism, Lipid Peroxides metabolism, Radiation Dosage, Rats, Rats, Wistar, Visual Cortex enzymology, Visual Cortex metabolism, Hypothalamus radiation effects, Microwaves adverse effects, Oxidative Stress, Visual Cortex radiation effects
Abstract

The article concerns biological effects of non-ionized electromagnetic irradiation which is considered in modern world as a serious ecological factor. Influence of decimetric microwave irradiation (460 MHz) on free radical processes in the rat brain tissues--visual cortex and hypothalamus--were investigated. Oxidative effects of both lipid peroxidation and specific activity of glutathione reductase were determined. It is shown that whole body irradiation for up to 4 weeks results in considerable changes of the above indices dependent on the irradiation intensity and age of the animals. Decimetric microwaves have oxidant effects at high intensity irradiation (SAR--15 mW/kg), while these effects are antioxidant at low intensity (SAR--5 mW/kg). Physiological implications of different oxidative metabolic responses of the hypothalamus and the cortex to microwaves irradiation are discussed.

Published
2004

50. [Theoretical conformational analysis of cardioactive peptides. I. Tetrapeptide Phe1-Met2-Arg3-Phe4-NH2 and pentapeptide Leu1-Pro2-Leu3-Arg4- NH2].

Author

Ismailova LI, Akhmedov NA, and Akhmedova SR

Subjects
Amino Acid Sequence, FMRFamide pharmacology, Heart drug effects, Models, Chemical, Neuropeptides pharmacology, Oligopeptides pharmacology, Protein Conformation, Static Electricity, FMRFamide chemistry, Neuropeptides chemistry, Oligopeptides chemistry
Abstract

By means of semi-empirical method, an a priori conformational analysis of a cardioactive peptides was carried out. Calculations yielded the values of all dihedral angles of the backbone and side chains of the peptides various forms as well as intra- and interresidue interaction energies.

Published
1997

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