scholarly journals Quaternary volcanic ash of Kharkiv region

2018 ◽  
Keyword(s):  
Volcanic Ash ◽  
Volcanic Glass ◽  
Refraction Index ◽  
Practical Significance ◽  
Molecular Water ◽  
Hydroxyl Groups ◽  
Average Percentage ◽  
Phlegraean Fields ◽  
Eolian Origin ◽  
Main Material

Formulation of the problem. The article is devoted to detail geological and mineralogical description of quaternary volcanic ash in Kharkiv region. The purpose of the article is to ground its origin. Presentation of the main material. Quaternary volcanic ash was discovered in Kharkiv region in the middle of last century. There are a few Late Neo-Pleistocene deposits of volcanic ash in Kharkiv region now. They are located in Kharkiv and near such villages as Russki Tishki, Novoselivka, Levkivka, Donetzke and Krasnokutsk. Such deposits of volcanic ash were found in the neighboring regions of the Eastern Ukraine - Lugansk, Donetsk, Dnieperpetrovsk and some other regions. Volcanic ash forms the elongated lenticular deposits in the loess loam strata. The contact of ash beds is clear with underlying loess and gradual with overlying loess. The ash lies 3-5 m below the surface of loess. These ashes are light-grey with feeble yellow or brown shades. Its thickness is up to 0.4 m. The particles of the ash are volcanic colourless isotropic glass with refraction index 1,517. Its forms are various. Plate isometric and elongated ash particles with even straight or cambered sides are the most widespread. Predominance of 0.005-0.1 mm particles in this ash rocks is confirmed by the results of mechanical analyses. This tephra is badly sorted. Their sort factor is 4.2-5.9. The ash deposits were formed by wind transportation of ash particles to wind shadow zones. The results of X-ray investigation are typical for glass. IR-spectra investigation revealed molecular water and hydroxyl groups in the volcanic ash. Chemical composition of the volcanic ash of Kharkiv region is characterized by the average percentage of SiO2 – 58.88, Al2O3 – 18.79, Na2O – 5.03, K2O – 6.30, Na2O+K2O – 11.33. Relation of Na2O to K2O is 0.80 and Na2O+K2O to Al2O3 is 0.60. It corresponds to trachyte and phonolite and is confirmed by the refraction index of glass particles. The volcanic glass particles are angular and non-rounded. This fact signifies the eolian origin of ash deposits. Moreover, numerous manifestations of volcanic ash scattered in loess loams are found in Kharkiv region. These loams contain only a few per cents of poorly rounded volcanic ash particles. The loess loams with scattered volcanic ash and volcanic ash deposits belong to the same stratigraphic datum - to the Bugskij horizon, which correspond to Wurmian stage. Conclusions. All tephra deposits of Kharkiv region are in the ash plume of the super-eruption, which occurred in Southern Italy about 39280 years ago (Campanian Ignimbrite eruption). Kharkiv objects fill territory in this plume between the ash depositions of Romania and Russian Voronezh region. They are similar to all other tephra localities of this plume. The volcanic ash was taken by air from the Phlegraean Fields though the distance between Kharkiv and this volcano is over 2000 km. Scientific novelty and practical significance. We can affirm that Kharkiv ash deposits are the result of distant ashfall of Phlegraean Fields super-eruption. The volcanic ash is a horizon marker in the Neo-Pleistocene strata and a datum mark for archaeological study of the Paleolithic cultures. Volcanic ash is a remarkable component of Kharkiv region geological monuments. Russki Tishki locality of volcanic ash is the best object in Kharkiv region. It is situated in 22 km north from Kharkiv. These geological sights have been used as objects of scientific tourism and native land study. Their protection is of highly necessity.

PODZOLIC SOILS WITH LUVISOLIC-LIKE MORPHOLOGIES IN THE UPPER SUBALPINE SUBZONE OF THE CANADIAN ROCKIES. 1. STRATIGRAPHY AND MINERALOGY

1981 ◽  
Vol 61 (2) ◽  
pp. 325-335 ◽  
Author(s):  
C.A.S. SMITH ◽  
G.M. COEN ◽  
D.J. PLUTH
Keyword(s):  
Volcanic Ash ◽  
Amorphous Material ◽  
Volcanic Glass ◽  
Fine Sand ◽  
Optical Identification ◽  
Sand Fraction ◽  
Parent Materials ◽  
Podzolic Soils ◽  
Surficial Deposits ◽  
Eolian Origin

A lithological and textural discontinuity within the sola of Podzolic soils of the upper subalpine bioclimatic subzone at Sunwapta Pass, Alberta was investigated. The physical and mineralogical variability of parent materials, and the origin and mode of deposition of an overlying silty deposit were evaluated. Evidence supported an eolian origin for the extensive, thin silty surficial deposits observed in the central Rockies. This material was composed of a mixture of volcanic ash and local detritus. Optical identification of the fine plus very fine sand fraction, separated according to specific gravity, indicated volcanic glass, quartz, and plagioclase to be abundant in the surficial material, and primary carbonate and quartz to be abundant in the underlying till. The clay-sized fractions in the surficial material were equally distinct from the underlying material, with amorphous material and chloritic intergrades present in the former, muscovite and chlorite below.

Comparison of Infra-Dry and AOAC Methods for Moisture in Food Products

1984 ◽  
Vol 47 (8) ◽  
pp. 611-614
Author(s):  
B. A. MINOR ◽  
K. A. SIMS ◽  
R. BASSETTE ◽  
D. Y. C. FUNG
Keyword(s):  
Wheat Flour ◽  
Food Products ◽  
Practical Significance ◽  
Good Precision ◽  
Average Percentage ◽  
Fresh Milk ◽  
Cooling Chamber ◽  
Precision And Accuracy ◽  
Potato Flakes ◽  
The Times

The Infra-Dry (IR) method was accurate, precise and faster than conventional (AOAC) procedures for moisture determinations in ten selected food products. The average percentage moisture by the IR method for 10 common food products and those by AOAC in parentheses are as follows: oatmeal 9.88 (9.87), cornmeal 10.86 (10.91), wheat flour 10.80 (10.80), grape nuts 4.73 (4.78), rice 12.39 (12.41), potato flakes 8.40 (8.36), bread crumbs 9.93 (9.99), noodles 9.58 (9.54), NFD milk 4.23 (4.24), and fresh milk 88.60 (88.71). The temperatures used for the IR method (135 to 155°C) were higher than those for the AOAC procedures (130°C for all products except NFD and fresh milk [100°C]); however, the times were considerably less (10 to 30 min) than for AOAC procedures (1 to 5 h). Standard deviations were generally <0.06%, except for cornmeal and noodles which were approximately 0.1%. Precisions were generally >97%. Upon removing the samples from the IR oven, results of good precision and accuracy were obtained by cooling the samples in a desiccator for 5 min or the built-in IR cooling chamber for 45 s. The recommended IR method uses a cooling chamber, is faster, and does not require a desiccator. Slightly lower precision and accuracy resulted when the entire IR oven was used. The best results were obtained using the back third of the oven. However, the slight difference in precision and accuracy is of little practical significance.

scholarly journals Hydrogen Speciation in Hydrated Layers on Nuclear Waste Glass

1986 ◽  
Vol 84 ◽  
Author(s):  
Roger D. Aines ◽  
Homer C. Weed ◽  
John K. Bates
Keyword(s):  
Nuclear Waste ◽  
Vapor Phase ◽  
Waste Glass ◽  
Hydroxyl Group ◽  
Molecular Water ◽  
Hydroxyl Groups ◽  
Phase Layer ◽  
Nuclear Waste Storage ◽  
Nuclear Waste Glass ◽  
Saturated Atmosphere

AbstractThe hydration of an outer layer on nuclear waste glasses is known to occur during leaching, but the actual speciation of hydrogen (as water or hydroxyl groups) in these layers has not been determined. As part of the Nevada Nuclear Waste Storage Investigations Project, we have used infrared spectroscopy to determine hydrogen speciations in three nuclear waste glass compositions (SRL-131 & 165, and PNL 76-68), which were leached at 90°C (all glasses) or hydrated in a vapor-saturated atmosphere at 202°C (SRL-131 only). Hydroxyl groups were found in the surface layers of all the glasses. In addition, molecular water was found in the surface of SRL-131 and PNL 76-68 glasses that had been leached for several months in deionized water, and in the vapor-hydrated sample. The water/hydroxyl ratio increases with increasing reaction time; molecular water makes up most of the hydrogen in the thick reaction layers on vapor-phase hydrated glass while only hydroxyl occurs in the least reacted samples. Using the known molar absorptivities of water and hydroxyl in silica-rich glass the vapor-phase layer contained 4.8 moles/liter of molecular water, and 0.6 moles water in the form hydroxyl. A 15 micrometer layer on SRL-131 glass formed by leaching at 90°C contained a total of 4.9 moles/liter of water, 2/3 of which was as hydroxyl. The unreacted bulk glass contains about 0.018 moles/liter water, all as hydroxyl.The amount of hydrogen added to the SRL-131 glass was about 70% of the original Na + Li content, not the 300% that would result from alkali-hydronium ion (H30+) interdiffusion. If all the hydrogen is then assumed to be added as the result of alkali-H+ interdiffusion, the molecular water observed may have formed from condensation of the original hydroxyl groups according to:20H = H20 molecular + 00where 00 refers to a bridging oxygen, and OH refers to a hydroxyl group attached to a silicate polymer. The hydrated layer on the nuclear waste glasses appears to be of relatively low water content (4 to 7% by weight) and is not substantially hydroxylated. Thus, these layers do not have many of the properties associated with “gel” layers.

Incorporation of Mg in phase Egg, AlSiO3OH: Toward a new polymorph of phase H, MgSiH2O4, a carrier of water in the deep mantle

2020 ◽  
Vol 105 (1) ◽  
pp. 132-135 ◽  
Author(s):  
Luca Bindi ◽  
Aleksandra Bendeliani ◽  
Andrey Bobrov ◽  
Ekaterina Matrosova ◽  
Tetsuo Irifune
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Lower Mantle ◽  
Water Cycle ◽  
Molecular Water ◽  
Hydroxyl Groups ◽  
X Ray Diffraction ◽  
Coordination Polyhedra ◽  
X Ray ◽  
Mg Substitution

Abstract The crystal structure and chemical composition of a crystal of Mg-bearing phase Egg with a general formula M1−x3+Mx2+SiO4H1+x (M3+ = Al, Cr; M2+ = Mg, Fe), where x = 0.35, produced by subsolidus reaction at 24 GPa and 1400 °C of components of subducted oceanic slabs (peridotite, basalt, and sediment), was analyzed by electron microprobe and single-crystal X-ray diffraction. Neglecting the enlarged unit cell and the consequent expansion of the coordination polyhedra (as expected for Mg substitution for Al), the compound was found to be topologically identical to phase Egg, AlSiO3OH, space group P21/n, with lattice parameters a = 7.2681(8), b = 4.3723(5), c = 7.1229(7) Å, β = 99.123(8)°, V = 223.49(4) Å3, and Z = 4. Bond-valence considerations lead to hypothesize the presence of hydroxyl groups only, thereby excluding the presence of the molecular water that would be present in the hypothetical end-member MgSiO3·H2O. We thus demonstrate that phase Egg, considered as one of the main players in the water cycle of the mantle, can incorporate large amounts of Mg in its structure and that there exists a solid solution with a new hypothetical MgSiH2O4 end-member, according to the substitution Al3+ ↔ Mg2+ + H+. The new hypothetical MgSiH2O4 end-member would be a polymorph of phase H, a leading candidate for delivering significant water into the deepest part of the lower mantle.

scholarly journals First Principles Mechanistic Study of Self-Limiting Oxidative Adsorption of Remote Oxygen Plasma During the Atomic Layer Deposition of Alumina

2018 ◽  
Author(s):  
Glen N. Fomengia ◽  
Michael Nolan ◽  
Simon D. Elliott
Keyword(s):  
Atomic Layer Deposition ◽  
First Principles ◽  
Density Functional ◽  
Atomic Layer ◽  
Molecular Water ◽  
Mechanistic Study ◽  
Hydroxyl Groups ◽  
Layer Deposition ◽  
Surface Intermediates ◽  
By Products

Plasma-enhanced atomic layer deposition (ALD) of metal oxides is a rapidly gaining interest especially in the electronics industry because of its numerous advantages over the thermal process. However, the underlying reaction mechanism is not sufficiently understood, particularly regarding saturation of the reaction and densification of the film. In this work, we employ first principles density functional theory (DFT) to determine the predominant reaction pathways, surface intermediates and by-products formed when constituents of O<sub>2</sub>-plasma or O<sub>3</sub> adsorb onto a methylated surface typical of TMA-based alumina ALD. The main outcomes are that a wide variety of barrierless and highly exothermic reactions can take place. This leads to the spontaneous production of various by-products with low desorption energies and also of surface intermediates from the incomplete combustion of –CH<sub>3</sub> ligands. Surface hydroxyl groups are the most frequently observed intermediate and are formed as a consequence of the conservation of atoms and charge when methyl ligands are initially oxidized (rather than from subsequent re-adsorption of molecular water). Anionic intermediates such as formates are also commonly observed at the surface in the simulations. Formaldehyde, CH<sub>2</sub>O, is the most frequently observed gaseous by-product. Desorption of this by-product leads to saturation of the redox reaction at the level of two singlet oxygen atoms per CH<sub>3</sub> group, where the oxidation state of C is zero, rather than further reaction with oxygen to higher oxidation states. We conclude that the self-limiting chemistry that defines ALD comes about in this case through the desorption by-products with partially-oxidised carbon. The simulations also show that densification occurs when ligands are removed or oxidised to intermediates, indicating that there may be an inverse relationship between Al/O coordination numbers in the final film and the concentration of chemically-bound ligands or intermediate fragments covering the surface during each ALD pulse. Therefore reactions that generate a bare surface Al will produce denser films in metal oxide ALD.

Investigation of structural and optical properties of zirconia dioxide nanoparticles by radiation and thermal methods

2020 ◽  
pp. 2150050
Author(s):  
G. T. Imanova ◽  
T. N. Agayev ◽  
S. H. Jabarov
Keyword(s):  
Zirconium Hydride ◽  
Molecular Water ◽  
Hydroxyl Groups ◽  
Peroxide Radical ◽  
Absorption Bands ◽  
Thermal Methods ◽  
Surface Hydroxyl ◽  
Radiation Induced ◽  
Decomposition Of Water

The X-ray diffraction (XRD) spectrum of the nano-ZrO2 compound was drawn, the crystal structure was determined at room temperature and under normal conditions. Radiation-thermal decomposition of water on nanosized ZrO2 in the temperature range of [Formula: see text]–673 K has been studied by Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. It has been shown that nanosized zirconium dioxide adsorbs water via the molecular and dissociative mechanisms. Intermediate products of the radiation-induced heterogeneous decomposition of water, namely, the molecular oxygen and hydrogen peroxide radical ions, zirconium hydride, and hydroxyl radicals have been detected. A comparative analysis of changes in the absorption bands (ABs) of molecular water and surface hydroxyl groups with temperature has been conducted, and the stimulating role of radiation in the radiation-thermal process of water decomposition has been revealed. With the participation of nano-ZrO2 during the radiation-heterogeneous decomposition of water to reveal the role of unbalanced cargo carriers that play the role of energy carriers under the influence of gamma-quantities in nano-ZrO2 and nano-[Formula: see text] systems paramagnetic centers, their origin and acquisition kinetics learned by the EPR method.

Weathering of volcanic ash in the cryogenic zone of Kamchatka, eastern Russia

Clay Minerals ◽  
2014 ◽  
Vol 49 (2) ◽  
pp. 195-212 ◽  
Author(s):  
E. Kuznetsova ◽  
R. Motenko
Keyword(s):  
Thermal Conductivity ◽  
Soil Water ◽  
Volcanic Ash ◽  
Volcanic Glass ◽  
Central Depression ◽  
Cryogenic Soils ◽  
Main Factors ◽  
Physical And Chemical ◽  
Eastern Russia

AbstractThe nature of the alteration of basaltic, andesitic and rhyolitic glass of Holocene and Pleistocene age and their physical and chemical environments have been investigated in the ash layers within the cryogenic soils associated with the volcanoes in the central depression of Kamchatka. One of the main factors controlling the alteration of the volcanic glass is their initial chemistry with those of andesitic (SiO2 = 53–65 wt.%) and basaltic (SiO2 < 53 wt.%) compositions being characterized by the presence of allophane, whereas volcanic glass of rhyolitic composition (SiO2>65 wt.%) are characterized by opal. Variations in the age of eruption of individual ashes, the amount and nature of the soil water, the depth of the active annual freeze-thawing layer, the thermal conductivity of the weathering soils, do not play a controlling role in the type of weathering products of the ashes but may affect their rates of alteration.

scholarly journals Detailed clay mineralogy of the Triassic-Jurassic boundary section at Kendlbachgraben (Northern Calcareous Alps, Austria)

Clay Minerals ◽  
2012 ◽  
Vol 47 (2) ◽  
pp. 177-189 ◽  
Author(s):  
N. Zajzon ◽  
F. Kristály ◽  
J. Pálfy ◽  
T. Németh
Keyword(s):  
Large Scale ◽  
Volcanic Ash ◽  
Clay Mineralogy ◽  
Volcanic Glass ◽  
Mass Extinctions ◽  
Humid Climate ◽  
Central Atlantic Magmatic Province ◽  
Central Atlantic ◽  
Moderate Climate ◽  
Shape And Size

AbstractThe Triassic-Jurassic boundary (TJB) is marked by one of the five largest Phanerozoic mass extinctions. To constrain existing models for TJB events, we obtained a stratigraphically highly resolved dataset from a marine section at Kendlbachgraben, Austria.The topmost Triassic Kössen Formation contains low to medium-charged smectite and vermiculite as alteration products of mafic-ultramafic minerals. The clay minerals in the boundary mudstone are kaolinite ⩾ illite + muscovite ⨠ smectite > chlorite. Predominant kaolinite suggests humid climate and abundant terrigenous input. In the lowermost Jurassic, the clay mineral pattern changes to illite + muscovite ⨠ kaolinite ⨠ smectite, which reflects change to less humid and more moderate climate.The topmost Kössen Formation also contains clay spherules. Their composition, shape and size indicate that they are alteration products of airborne volcanic glass droplets solidified in the air, settled in the sea and altered rapidly with negligible transport in terrestrial or marine environments. Our data are consistent with sudden climatic change at the TJB, as a result of large-scale volcanic activity of the Central Atlantic Magmatic Province which produced distal airfall volcanic ash.

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