Structural changes in smectites subjected to mechanochemical activation: The effect of the occupancy of the octahedral sites

2021 ◽  
Vol 213 ◽  
pp. 106214
Author(s):  
Helena Pálková ◽  
Martin Barlog ◽  
Jana Madejová ◽  
Viktor Hronský ◽  
Lukáš Petra ◽  
...  
Keyword(s):  
Structural Changes ◽  
Mechanochemical Activation ◽  
Octahedral Sites

MECHANOCHEMICAL ACTIVATION METHOD TECHNOLOGICAL PROCESS REFINING OF VEGETABLE OILS

2020 ◽  
Author(s):  
В.И. МАРТОВЩУК ◽  
С.А. КАЛМАНОВИЧ ◽  
А.А. ЛОБАНОВ ◽  
Е.В. МАРТОВЩУК
Keyword(s):  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Acid Composition ◽  
Vegetable Oils ◽  
Structural Changes ◽  
Mechanochemical Activation ◽  
Cavitation Effect ◽  
Temperature Mode ◽  
The Stability ◽  
Local Pressures

Исследовано влияние механохимической активации на гидратируемость фосфолипидов растительных масел. Для эксперимента использовали механохимический активатор, обеспечивающий высокие локальные давления, сдвиговые деформации и кавитационный эффект, при следующих параметрах работы: давление на контактирующих поверхностях 70 МПа, частота 180 Гц, скорость сдвига 10200 с–1, размер капли эмульсии 1–2 мкм. Обработку образцов подсолнечного масла осуществляли в течение от 0 до 80 с при температурах 50, 60 и 70°С. Активность фосфолипидов оценивали по величине их адсорбции на границе с полярной поверхностью (водой) в оптимальном температурном режиме при обработке в механохимическом активаторе и без нее. Установлено, что механохимическая активация способствует снижению энергии активации с 6,4 до 4,7 кДж/моль за счет химических и структурных изменений фосфолипидов. В жирнокислотном составе фосфолипидов на 10–12% увеличилось содержание олеиновой кислоты при соответствующем уменьшении линолевой; в фосфатидилэтаноламинах и фосфатидилсеринах отмечено увеличение до 3% содержания пальмитиновой кислоты и незначительно – стеариновой кислоты. Эти изменения жирнокислотного состава и физических свойств фосфолипидов способствуют повышению их гидратируемости и уменьшению доли полиненасыщенных жирных кислот, что должно обеспечить стабильность обработанных в механохимическом активаторе масел к окислению при хранении. The effect of mechanochemical activation on the hydration of phospholipids of vegetable oils has been studied. A mechanochemical activator providing high local pressures, shear deformations and cavitation effect was used for the experiment with the following operating parameters: pressure on the contact surfaces of 70 MPa, frequency of 180 Hz, shear rate of 10200 s–1, the size of the emulsion drop of 1–2 microns. Processing of sunflower oil samples was carried out during 0 to 80 s at temperatures of 50, 60 and 70°C. The activity of phospholipids was estimated by the amount of their adsorption at the border with the polar surface (water) in the optimal temperature mode when processed in a mechanochemical activator and without it. It was found that mechanochemical activation contributes to a decrease in the activation energy from 6,4 to 4,7 kJ/mol due to chemical and structural changes in phospholipids. In the fatty acid composition of phospholipids, the content of oleic acid increased by 10–12% with a corresponding decrease in linoleic acid; in phosphatidylethanolamines and phosphatidylserines, the increase in the content of palmitic acid was noted to 3%, and stearic acid – slightly. These changes in the fatty acid composition and physical properties of phospholipids contribute to increasing their hydration and reducing the proportion of polyunsaturated fatty acids, which should ensure the stability of the oils processed in the mechanochemical activator to oxidation during storage.

Catalytic Processing of Coal into Liquid Fuels: Mechanochemical Activation of Coal

2012 ◽  
Vol 535-537 ◽  
pp. 2108-2111
Author(s):  
Kayrbekov Zhaksyntay ◽  
Aubakirov Ermek ◽  
Myltykbaeva Zhannur
Keyword(s):  
Structural Changes ◽  
Mechanochemical Activation ◽  
Gasoline Fraction ◽  
Degree Of Conversion ◽  
Mechanochemical Treatment ◽  
Liquid Fuels ◽  
Mechanochemical Processing ◽  
Liquid Products ◽  
Catalytic Processing

This paper presents the results of the influence of mechanochemical treatment Karazhyrin coal on the yield of liquid products. Under the mechanochemical processing of coal along with the dispersion its activation is accompanied by significant structural changes of OMC. It is shown that the preliminary mechanochemical treatment contribute to the increase of the degree of conversion of coal in the process of hydrogenation. A more profound transformation of OMC is confirmed by an increase of the yield of liquid products, particularly, the content of the gasoline fraction is increasing.

Investigation of the structural changes in bayerite during mechanochemical activation

1988 ◽  
Vol 37 (6) ◽  
pp. 1061-1065
Author(s):  
S. M. Paramzin ◽  
L. M. Plyasova ◽  
O. P. Krivoruchko ◽  
B. P. Zolotovskii ◽  
S. V. Bogdanov ◽  
...  
Keyword(s):  
Structural Changes ◽  
Mechanochemical Activation

scholarly journals The Atomic Arrangement of Cr-rich Tourmaline from the #1 Mine, Balmat, St. Lawrence County, New York, USA

Minerals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 398 ◽  
Author(s):  
Steven Dannenberg ◽  
Devany Di Paolo ◽  
Alix Ehlers ◽  
Kyle McCarthy ◽  
Mark Mancini ◽  
...  
Keyword(s):  
New York ◽  
Structural Changes ◽  
Bond Valence ◽  
Northwestern Part ◽  
Atomic Arrangement ◽  
Octahedral Sites ◽  
A Value ◽  
Low Concentrations ◽  
Lawrence County ◽  
Bond Valence Sum

Chromium-bearing tourmalines are rare. Chromium-rich tourmaline from the northwestern part of the Adirondack Mountains in the Adirondack Lowlands is among the most chromium-rich tourmalines found to date. The mineral, with >21.0 wt. % Cr2O3, is from the marble-hosted talc–tremolite–cummingtonite schist in the #1 mine in Balmat, St. Lawrence County, New York. The atomic arrangement of the sample (a = 16.0242(3) Å, c = 7.3002(2) Å) was refined to R1 = 0.0139. The composition, from chemical analyses and optimization of the formula, is X(Ca0.22Na0.69K0.01) Y(Cr3+1.68Mg0.80Ti0.13V0.06Mn0.02Fe0.02Li0.29) Z(Al3.11Cr3+1.18Mg1.70Fe0.01) T(Si5.93Al0.07) B3O27 OH3.99 F0.01. There has been extensive debate over the ordering of Cr3+ between the tourmaline Y and Z octahedral sites. Recent work has suggested that, at low concentrations (<~1.03 apfu), the substituent Cr3+ is ordered into the Y-site, whereas, at greater concentrations, the substituent is disordered over both octahedral sites. An analysis of nine recently published, high-precision structures of chromium-bearing tourmaline, in combination with the Adirondack tourmaline, suggests that structural changes to the Y-site at low concentrations of Cr3+ induce changes in the Z-site that make it more amenable to incorporation of the Cr3+ substituents by increasing <Z–O>. The bond lengths change to lower the bond-valence sum of Cr3+ in the Z-site of the chromium-dravite, making that site more amenable to the substituent. Calculations suggest that the Z-site begins to accept substituent Cr3+ when the bond valence sum of that ion in Z reduces to a value of ~3.36 valence units.

scholarly journals Mössbauer spectroscopy study of 60P2O5-40Fe2O3 glass crystallization

Nukleonika ◽  
2015 ◽  
Vol 60 (1) ◽  
pp. 133-136 ◽  
Author(s):  
Paweł Stoch ◽  
Agata Stoch
Keyword(s):  
Heat Treatment ◽  
Mössbauer Spectroscopy ◽  
Structural Changes ◽  
Mossbauer Spectroscopy ◽  
Local Environment ◽  
Iron Ions ◽  
Spectroscopy Study ◽  
Glass Crystallization ◽  
Octahedral Sites ◽  
Mößbauer Spectroscopy

Abstract 60P2O5-40Fe2O3 glass was synthesized and 57Fe Mössbauer spectroscopy study was presented. The main goal of the research was to investigate structural changes of local environment of iron ions during gradual crystallization of the glass. It was observed that some changes were evidenced at temperature of heat treatment higher than 400°C, above which content of tetrahedrally coordinated Fe3+ was increased in cost of octahedral sites. This led to formation of areas of nucleation of α-FePO4. Crystallization of α-Fe3(P2O7)2 and Fe2P2O7 was also observed.

scholarly journals The local structure around Ge atoms in Ge-doped magnetite thin films

2020 ◽  
Vol 39 (1) ◽  
pp. 645-662
Author(s):  
Kozo Shinoda ◽  
Seishi Abe ◽  
Kazumasa Sugiyama ◽  
Yoshio Waseda
Keyword(s):  
Thin Films ◽  
Local Structure ◽  
Structural Changes ◽  
Tetrahedral Site ◽  
Type Structure ◽  
Spinel Type ◽  
Composite Target ◽  
Octahedral Sites ◽  
Radio Frequency Sputtering ◽  
X Ray Absorption

AbstractDistribution of Ge atoms between tetrahedral and octahedral sites in the spinel-type structure of Fe2.64Ge0.36O4 thin films fabricated by radio frequency sputtering with a composite target of magnetite and Ge has been investigated by extended X-ray absorption fine structure analysis. The local structural changes around the Ge atoms in the films induced by annealing at 573 and 873 K are discussed through comparison of the local structure for sintered crystalline Fe2.7Ge0.3O4 in which Ge atoms preferentially located at the tetrahedral site of the spinel-type structure. This work provides successful information on the structural change with magnetic property of the thin films as follows: the Ge atoms statistically distributed at the tetrahedral and octahedral sites of the as-synthesized films and preferentially occupied the tetrahedral site by annealing at 873 K corresponding to the increase in magnetization.

Fine Structural Changes in the Microvasculature of the Mouse Pinna: Aging and Radiation Injury

1974 ◽  
Vol 32 ◽  
pp. 54-55
Author(s):  
S. Phyllis Steamer ◽  
Rosemarie L. Devine
Keyword(s):  
Structural Changes ◽  
Radiation Treatment ◽  
Arterial Stenosis ◽  
Ultrastructural Changes ◽  
Vascular Effects ◽  
Microvascular Changes ◽  
Surrounding Connective Tissue ◽  
Fission Neutrons ◽  
Total Body

The importance of radiation damage to the skin and its vasculature was recognized by the early radiologists. In more recent studies, vascular effects were shown to involve the endothelium as well as the surrounding connective tissue. Microvascular changes in the mouse pinna were studied in vivo and recorded photographically over a period of 12-18 months. Radiation treatment at 110 days of age was total body exposure to either 240 rad fission neutrons or 855 rad 60Co gamma rays. After in vivo observations in control and irradiated mice, animals were sacrificed for examination of changes in vascular fine structure. Vessels were selected from regions of specific interest that had been identified on photomicrographs. Prominent ultrastructural changes can be attributed to aging as well as to radiation treatment. Of principal concern were determinations of ultrastructural changes associated with venous dilatations, segmental arterial stenosis and tortuosities of both veins and arteries, effects that had been identified on the basis of light microscopic observations. Tortuosities and irregularly dilated vein segments were related to both aging and radiation changes but arterial stenosis was observed only in irradiated animals.

Evaluation of single-electron movies of glutamine synthetase molecules

1983 ◽  
Vol 41 ◽  
pp. 280-281
Author(s):  
W. Kunath ◽  
E. Zeitler ◽  
M. Kessel
Keyword(s):  
Electron Microscope ◽  
Glutamine Synthetase ◽  
Electron Irradiation ◽  
Structural Damage ◽  
Structural Changes ◽  
Single Electron ◽  
Continuous Series ◽  
Digital Recording ◽  
Recording Device ◽  
Low Exposure

The features of digital recording of a continuous series (movie) of singleelectron TV frames are reported. The technique is used to investigate structural changes in negatively stained glutamine synthetase molecules (GS) during electron irradiation and, as an ultimate goal, to look for the molecules' “undamaged” structure, say, after a 1 e/Å2 dose.The TV frame of fig. la shows an image of 5 glutamine synthetase molecules exposed to 1/150 e/Å2. Every single electron is recorded as a unit signal in a 256 ×256 field. The extremely low exposure of a single TV frame as dictated by the single-electron recording device including the electron microscope requires accumulation of 150 TV frames into one frame (fig. lb) thus achieving a reasonable compromise between the conflicting aspects of exposure time per frame of 3 sec. vs. object drift of less than 1 Å, and exposure per frame of 1 e/Å2 vs. rate of structural damage.

Fine Structural Changes in the Adenohypophyses of Rats Following Destruction of the Pituitary Stalk

1977 ◽  
Vol 35 ◽  
pp. 496-497
Author(s):  
K. Kovacs ◽  
E. Horvath ◽  
J. M. Bilbao ◽  
F. A. Laszlo ◽  
I. Domokos
Keyword(s):  
Structural Changes ◽  
Tissue Injury ◽  
Anterior Lobe ◽  
Uranyl Acetate ◽  
Male Rats ◽  
Pituitary Stalk ◽  
Sequence Of Events ◽  
Pituitary Glands ◽  
Electrolytic Lesions ◽  
Ultrathin Sections

Electrolytic lesions of the pituitary stalk in rats interrupt adenohypophysial blood flow and result in massive infarction of the anterior lobe. In order to obtain a deeper insight into the morphogenesis of tissue injury and to reveal the sequence of events, a fine structural investigation was undertaken on adenohypophyses of rats at various intervals following destruction of the pituitary stalk.The pituitary stalk was destroyed electrolytically, with a Horsley-Clarke apparatus on 27 male rats of the R-Amsterdam strain, weighing 180-200 g. Thirty minutes, 1,2,4,6 and 24 hours after surgery the animals were perfused with a glutaraldehyde-formalin solution. The skulls were then opened and the pituitary glands removed. The anterior lobes were fixed in glutaraldehyde-formalin solution, postfixed in osmium tetroxide and embedded in Durcupan. Ultrathin sections were stained with uranyl acetate and lead citrate and investigated with a Philips 300 electron microscope.

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