scholarly journals Characteristics of hydrate-bound gas retrieved at the Kedr mud volcano (southern Lake Baikal)

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Akihiro Hachikubo ◽  
Hirotsugu Minami ◽  
Satoshi Yamashita ◽  
Andrey Khabuev ◽  
Alexey Krylov ◽  
...  
Keyword(s):  
Lake Baikal ◽  
Gas Hydrates ◽  
Sediment Cores ◽  
Mud Volcano ◽  
Crystallographic Structure ◽  
X Ray Diffraction ◽  
High Concentration ◽  
Lake Bottom ◽  
Diffraction Patterns ◽  
Lake Bottom Sediments

Abstract We reported the characteristics of hydrate-bound hydrocarbons in lake-bottom sediments at the Kedr mud volcano in Lake Baikal. Twenty hydrate-bearing sediment cores were retrieved, and methane-stable isotopes of hydrate-bound gases (δ13C and δ2H of − 47.8‰ to − 44.0‰ V-PDB and − 280.5‰ to − 272.8‰ V-SMOW, respectively) indicated their thermogenic origin accompanied with secondary microbial methane. Powder X-ray diffraction patterns of the crystals and molecular composition of the hydrate-bound gases suggested that structure II crystals showed a high concentration of ethane (around 14% of hydrate-bound hydrocarbons), whereas structure I crystals showed a relatively low concentration of ethane (2–5% of hydrate-bound hydrocarbons). These different crystallographic structures comprised complicated layers in the sub-lacustrine sediment, suggesting that the gas hydrates partly dissociate, concentrate ethane and form structure II crystals. We concluded that a high concentration of thermogenic ethane primarily controls the crystallographic structure of gas hydrates and that propane, iso-butane (2-methylpropane) and neopentane (2,2-dimethylpropane) are encaged into crystals in the re-crystallisation process.

Thermal anomalies associated with shallow gas hydrates in the K-2 mud volcano, Lake Baikal

2012 ◽  
Vol 32 (5-6) ◽  
pp. 407-417 ◽  
Author(s):  
Jeffrey Poort ◽  
Oleg M. Khlystov ◽  
Lieven Naudts ◽  
Albert D. Duchkov ◽  
Hitoshi Shoji ◽  
...  
Keyword(s):  
Lake Baikal ◽  
Gas Hydrates ◽  
Mud Volcano ◽  
Shallow Gas ◽  
Thermal Anomalies

scholarly journals Polymorphism of tricalcium silicate in Portland cement: A fast visual identification of structure and superstructure

2003 ◽  
Vol 18 (1) ◽  
pp. 7-15 ◽  
Author(s):  
M. Courtial ◽  
M.-N. de Noirfontaine ◽  
F. Dunstetter ◽  
G. Gasecki ◽  
M. Signes-Frehel
Keyword(s):  
Portland Cement ◽  
Structural Model ◽  
Rietveld Analysis ◽  
Tricalcium Silicate ◽  
Crystallographic Structure ◽  
X Ray Diffraction ◽  
Diffraction Patterns ◽  
Xrd Patterns ◽  
Industrial Compounds ◽  
Open Question

So-called alite is a solid solution of tricalcium silicate Ca3SiO5 with a few percent of impurities. It constitutes the major phase of anhydrous Portland cement. In industrial compounds, alite crystallizes into two monoclinic forms designated M1 and M3. The possibility of correlation between the crystallographic structure of the clinker and its reactivity is still an open question. The answer of such a question involves a proper quantitative analysis of the various phases—including the exact alite polymorph—of the industrial product. The rather similar structure of the two alites makes it difficult to distinguish them from their XRD patterns. This paper shows that five angular windows in the X-ray diffraction patterns can be used with synthetic alites as well as industrial compounds, to identify the nature of the actual polymorph (M1 or M3) present and the structural model to be used (with or without superstructure) in subsequent Rietveld analysis of the data.

scholarly journals Defect-assisted synthesis of magneto-plasmonic silver-spinel ferrite heterostructures in a flower-like architecture

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Marco Sanna Angotzi ◽  
Valentina Mameli ◽  
Claudio Cara ◽  
Vincenzo Grillo ◽  
Stefano Enzo ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Spinel Ferrite ◽  
High Resolution Electron Microscopy ◽  
Careful Study ◽  
X Ray Diffraction ◽  
High Concentration ◽  
Resolution Electron ◽  
Wide Range ◽  
Controlled Morphology ◽  
Diffraction Patterns

Abstract Artificial nano-heterostructures (NHs) with controlled morphology, obtained by combining two or more components in several possible architectures, make them suitable for a wide range of applications. Here, we propose an oleate-based solvothermal approach to design silver-spinel ferrite flower-like NHs. Small oleate-coated silver nanoparticles were used as seeds for the growth of magnetic spinel ferrite (cobalt ferrite and spinel iron oxide) nanodomains on their surface. With the aim of producing homogeneous flower-like heterostructures, a careful study of the effect of the concentration of precursors, the reaction temperature, the presence of water, and the chemical nature of the spinel ferrite was carried out. The magnetic and optical properties of the NHs were also investigated. A heterogeneous growth of the spinel ferrite phase on the silver nanoparticles, through a possible defect-assisted mechanism, was suggested in the light of the high concentration of stacking faults (intrinsic and twins) in the silver seeds, revealed by Rietveld refinement of powder X-ray diffraction patterns and High-Resolution electron microscopy.

STRUCTURE, MORPHOLOGY, AND COMPOSITION OF NATURAL GAS HYDRATES SAMPLED IN THE KEDR-1 MUD VOLCANO (LAKE BAIKAL)

2021 ◽  
Vol 62 (6) ◽  
pp. 889-896
Author(s):  
A. Yu. Manakov ◽  
O. M. Khlystov ◽  
A. K. Sagidullin ◽  
T. P. Adamova ◽  
A. Khabuev ◽  
...  
Keyword(s):  
Natural Gas ◽  
Lake Baikal ◽  
Gas Hydrates ◽  
Mud Volcano ◽  
Natural Gas Hydrates ◽  
Structure Morphology

scholarly journals The Soil Properties of Lake-Bottom Sediments in the Lake Baikal Gas Hydrate Province

2009 ◽  
Vol 49 (5) ◽  
pp. 757-775 ◽  
Author(s):  
Satsuki Kataoka ◽  
Satoshi Yamashita ◽  
Takayuki Kawaguchi ◽  
Teruyuki Suzuki
Keyword(s):  
Soil Properties ◽  
Lake Baikal ◽  
Bottom Sediments ◽  
Gas Hydrate ◽  
Lake Bottom ◽  
Lake Bottom Sediments

Electrical properties of epoxy-glue/(Bi12MnO20–BiMn2O5) composite

2017 ◽  
Vol 52 (10) ◽  
pp. 1305-1315 ◽  
Author(s):  
Anna Z Szeremeta ◽  
Andrzej Molak ◽  
Sebastian Pawlus ◽  
Janusz Koperski ◽  
Agnieszka Leonarska
Keyword(s):  
Electrical Properties ◽  
Relaxation Times ◽  
Crystallographic Structure ◽  
X Ray Diffraction ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
Interfacial Layers ◽  
Backscattered Electron ◽  
Diffraction Patterns ◽  
Tan Δ

Electrical properties of composite consisted of epoxy-glue and powdered bismuth manganite Bi12MnO20–BiMn2O5 ceramics were studied. Samples contained 66 wt% of bismuth manganite. Secondary electron images and backscattered electron images were collected for the epoxy-glue and the epoxy-glue/bismuth manganite samples. Microanalysis shown that majority of bismuth manganite powder was homogenously distributed in epoxy-glue matrix. Lack of changes in crystallographic structure, in 300–450 K range, was deduced from the X-ray diffraction patterns. The electric impedance was measured at radio-frequencies. It was analysed using electric permittivity ɛ*( T, f ) and modulus M″(T, f ) representation. Epoxy-glue/bismuth manganite composite exhibited, at room temperature, conductivity, σ( f ) = 10−5 to 10−7 S m−1, permittivity, ɛ′≈10, losses, tan  δ = 0.2–0.8 and dispersion markedly lower than bismuth manganite ceramics. Electric relaxation was induced in epoxy-glue/bismuth manganite composite samples. The Vogel–Fulcher–Tammann equation was fitted to relaxation times temperature dependence, obtained from M″(T, f ). The estimated values of Vogel–Fulcher equation parameters were frequency f0 = 2.2 × 108 Hz, energy UT = 1050 K and glass transition temperature Tg = 282 K. The relaxation times were attributed to strains, which would occur at interfacial layers between the bismuth manganite grain and the polymer matrix.

scholarly journals Determination of the Mineral Composition of the Lake Bottom Sediments by X-Ray Diffraction Method and Physico-Chemical Modelling

2019 ◽  
pp. 382-394
Author(s):  
Roman V. Smelyy ◽  
Ekaterina V. Kaneva ◽  
Anastasiya V. Oshchepkova ◽  
Valerii A. Bychinskii ◽  
Tat’yana S. Aisueva ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Mineral Composition ◽  
Bottom Sediments ◽  
Diffraction Method ◽  
Least Square ◽  
X Ray Diffraction ◽  
X Ray ◽  
Relative Standard ◽  
Lake Bottom ◽  
Lake Bottom Sediments

The paper reports comparison of three approaches to define the contents of minerals and mineral groups in the carbonate-silicate lake bottom sediments. The two approaches are based on the method of X-ray powder diffraction. The first one treats with the Rietveld Method in the software DIFFRAC Plus diffractometer D8 Advance (PDF-2 database). The second one uses the method of reference intensities (corundum ratios) and optimization of the model powder patterns from the X-ray phase standards of PDF-2 database and equations of the element balance with regularization of the least square functional. The third approach of physic-chemical modeling selects probable single mineral and multi-component phases through modelling the sold solutions, and it uses the data on the element composition obtained by XRF technique, as well as the data of X-ray diffraction on the qualitative mineral composition. Thirty samples of bottom sediment cores taken in the Zun-Torey Lake in East Siberia were analyzed by the three approaches described herein. The contents of mineral groups (feldspars, quartz, clay minerals and carbonates) varied within the range 10-40 mass %. The discrepancies between obtained results show the standard deviation ranging from 2 to 9 mass %. A relative standard deviation commonly provides the value below 30 %, so such determinations could be considered quantitative ones. With regard to the acquired data, it is hard to prefer this or that approach. Available data was employed to assess the error of X-ray phase powder analysis in measuring the abundance of mineral groups in the carbonate-silicate sedimentary rocks in the absence of reference materials to compare with certified mineral composition

Structure, morphology and composition of natural gas hydrates collected at mud volcano Kedr-1 (Lake Baikal)

2021 ◽  
Vol 62 (6) ◽  
Author(s):  
А.Ю. Манаков ◽  
О.М. Хлыстов ◽  
А.К. Сагидуллин ◽  
Т.П. Адамова ◽  
А. Хабуев ◽  
...  
Keyword(s):  
Natural Gas ◽  
Lake Baikal ◽  
Gas Hydrates ◽  
Mud Volcano ◽  
Natural Gas Hydrates ◽  
Structure Morphology

Sedimentary analysis and magnetic properties of Lake Anónima, Vega Island

2017 ◽  
Vol 29 (5) ◽  
pp. 429-444 ◽  
Author(s):  
Marcos A.E. Chaparro ◽  
Mauro A.E. Chaparro ◽  
Francisco E. Córdoba ◽  
Karina L. Lecomte ◽  
José D. Gargiulo ◽  
...  
Keyword(s):  
Integrated Analysis ◽  
X Ray Diffraction ◽  
Grain Sizes ◽  
Fine Grain ◽  
Lake Bottom ◽  
Lake Bottom Sediments ◽  
Physicochemical Data ◽  
Spectroscopy Studies ◽  
Multiparameter Analysis ◽  
The Antarctic

AbstractDuring the summer Lake Anónima experiences important changes in salinity and lake level fluctuations. Physicochemical data and field observations indicate that evaporative processes are dominant and that the water inflow is mainly provided by snow meltwater and streams. A multiproxy analysis of data from lake bottom sediments suggests that the main surface stream located south-west of the lake controls the clastic input and the spatial variation of sediment composition. Through an integrated analysis (magnetic, X-ray diffraction and Fourier transform infrared spectroscopy studies) magnetite and greigite minerals were identified in these lake sediments. Such ferrimagnetic minerals have ultra-fine grain sizes (<0.1 μm). Magnetic parameters and non-magnetic variables analysed by multivariate statistics reveal significant differences between silt facies (e.g. mass-specific susceptibility χ=109.6×10-8 m3 kg-1, remanent coercivity Hcr=49.2 mT and total organic carbon (TOC)=1.11%) and sand facies (e.g. χ=82.1×10-8 m3 kg-1, Hcr=44.7 mT and TOC=0.70%), and four recent depositional sub-environments were identified and characterized in Lake Anónima. This multiparameter analysis contributes to the understanding of present-day lacustrine dynamic and sedimentary processes. Lake Anónima may provide a useful analogue for the interpretation of other lacustrine basins in the Antarctic region.

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