Phase equilibriums in the carbide area of the «iron-carbon» diagram. Part 1. Physico-chemical identification of carbide phases

2019 ◽

Vol 85 (2) ◽

pp. 69-79

Author(s):

Inessa Novoselova ◽

Serhii Kuleshov

Keyword(s):

Solid Solution ◽

Alkali Metal ◽

High Speed ◽

Carbon Nanomaterials ◽

Carbon Deposition ◽

Carbide Phases ◽

Physico Chemical ◽

Graphite Deposition ◽

Predominant Process ◽

Oxide Ions

An analysis of the decomposition potentials of lithium, sodium, potassium, calcium, barium, and magnesium carbonates with different versions of cathode products (elemental carbon, carbon monoxide, metal and carbide) in the range of 300-1900 K showed that for K2CO3 deposition of alkali metal on the cathode is most energetically profitable process at all temperatures. For Na2CO3 it is possible to obtain carbon at T < 1000 K. With temperature increase, the predominant process is the reduction of alkali metal. For Li2CO3, CaCO3, BaCO3, MgCO3 at T < 950 °C carbon deposition will be more advantageous, at higher temperatures reduction up to CO will be more advantageous. The decomposition of CO2 flows at more positive potentials compared with carbonate systems. However, low activity of CO2 in carbonate-containing melts will prevent the significant contribution of this reaction to the electrode process. Thermodynamic calculations of the dependence of the carbon deposition potentials from carbonate anion on the acidity of the melt (concentration of oxide ions) show the possibility of displacing this potential up to 0.8 V by changing the acid-base properties of the melt. On the basis of the analysis of binary phase diagrams, Me–C and MeC–C, criteria for selecting the cathode material for generation of the tubular structure of graphite are established. The diagrams should contain: (1) – solid solutions of C–Me at a temperature of 700–900 °C and sufficient solubility of carbon (up to ~ 1 at.%) in the metal should be observed; (2) – after saturation of the solid solution with carbon, the precipitation (precipitation) of graphite from the metal should occur without the formation of intermediate carbide phases; (3) – in the case of the formation of carbides, the diffusion of carbon in the solid solution С–Ме and in the carbide phase MeС should flow with high speed and quickly reach the concentration of carbon saturation for graphite deposition.

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Pharmacognostic Identification of the Green Peel of Juglans mandshurica Maxim. from Different Regions and Harvest Times

10.21203/rs.3.rs-861304/v1 ◽

2021 ◽

Author(s):

Jielin Chen ◽

Chao Wang ◽

Yongjie Yan ◽

Lihong Wang

Keyword(s):

High Performance ◽

Paraffin Section ◽

Green Light ◽

Growth Period ◽

Liaoning Province ◽

Morphological Identification ◽

Heilongjiang Province ◽

Chemical Identification ◽

Juglans Mandshurica ◽

Physico Chemical

Abstract Background: The green peel of Juglans mandshurica Maxim. (QLY) can be used as medicine, also known as Qinglongyi[1]. The aim of this study was to identify QLY from the different regions and harvest times by pharmacognostic identification.Methods: In this study, the morphological character, microscopic character and juglone’s content of QLY from different regions and harvest times were compared by morphological identification, paraffin section and powder section, physico-chemical identification and High Performance Liquid Chromatography (HPLC).Results: Morphological identification results that the colour of outer surfaces of peels which harvested from Tangyuan county of Heilongjiang Province in July, August and September are respectively yellow brown, tan and black brown , and the color of the solution graded gradually from light brown yellow to brownish black by water-based test (WBT). The colour of outer surfaces of peels which harvested from Changbai county of Jilin Province in July, August and September are respectively yellowish white, brownish yellow and pale brown, and the color of the solution gradually changed from light brown to dark brown by WBT. As well as the colour of outer surfaces of peels which harvested from Qingyuan county of Liaoning Province in July, August and respectively September are Light yellowish green, light brownish green and brown green, and the color of the solution gradually changed from light green to dark brown by WBT. With the increase of growth period, the number of microscopic characteristics of different Qinglongyi increased. Through physico-chemical identification, it was found that the yield of juglone in QLY picked on September 21, 2016 was the highest, and the content of juglone, whose order was Heilongjiang > Jilin > Liaoning, was as high as 203.476 μg/g.Conclusions: Through comparison, it is concluded that Heilongjiang Province is one of the high-quality producing areas of QLY, and its best harvest time is in the middle and first ten-day period of September to harvest QLY without softening, yellowing and decay. This experiment provides a theoretical basis for the determination of the best harvest conditions in QLY and the establishment of identification standards for medicinal materials.

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Decoration of specific sites on freeze-fractured membranes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100081565 ◽

1978 ◽

Vol 36 (2) ◽

pp. 140-141

Author(s):

H. Gross ◽

H. Moor

Keyword(s):

Pure Water ◽

Freeze Fracture ◽

Chemical Properties ◽

Surface Forces ◽

Sulfate Pentahydrate ◽

Copper Sulfate Pentahydrate ◽

Physico Chemical ◽

Water Of Hydration ◽

Small Container ◽

Binding Forces

Fracturing under ultrahigh vacuum (UHV, p ≤ 10-9 Torr) produces membrane fracture faces devoid of contamination. Such clean surfaces are a prerequisite foe studies of interactions between condensing molecules is possible and surface forces are unequally distributed, the condensate will accumulate at places with high binding forces; crystallites will arise which may be useful a probes for surface sites with specific physico-chemical properties. Specific “decoration” with crystallites can be achieved nby exposing membrane fracture faces to water vopour. A device was developed which enables the production of pure water vapour and the controlled variation of its partial pressure in an UHV freeze-fracture apparatus (Fig.1a). Under vaccum (≤ 10-3 Torr), small container filled with copper-sulfate-pentahydrate is heated with a heating coil, with the temperature controlled by means of a thermocouple. The water of hydration thereby released enters a storage vessel.

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A General Method for Spectrometer Design in the Scoff Approximation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100092657 ◽

1976 ◽

Vol 34 ◽

pp. 538-539

Author(s):

J. R. Fields

Keyword(s):

Electron Microscope ◽

Transmission Electron Microscope ◽

Energy Analysis ◽

Incident Beam ◽

Scanning Transmission Electron Microscope ◽

Chemical Identification ◽

Scanning Transmission Electron ◽

Transmission Electron ◽

Scanning Transmission ◽

General Method

The energy analysis of electrons scattered by a specimen in a scanning transmission electron microscope can improve contrast as well as aid in chemical identification. In so far as energy analysis is useful, one would like to be able to design a spectrometer which is tailored to his particular needs. In our own case, we require a spectrometer which will accept a parallel incident beam and which will focus the electrons in both the median and perpendicular planes. In addition, since we intend to follow the spectrometer by a detector array rather than a single energy selecting slit, we need as great a dispersion as possible. Therefore, we would like to follow our spectrometer by a magnifying lens. Consequently, the line along which electrons of varying energy are dispersed must be normal to the direction of the central ray at the spectrometer exit.

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Activation of cytochrome c to a peroxidase compound I-type intermediate by H2O2: relevance to redox signalling in apoptosis

Biochemical Society Symposium ◽

10.1042/bss0710097 ◽

2004 ◽

Vol 71 ◽

pp. 97-106 ◽

Cited By ~ 10

Author(s):

Mark Burkitt ◽

Clare Jones ◽

Andrew Lawrence ◽

Peter Wardman

Keyword(s):

Cytochrome C ◽

Hydroxyl Radical ◽

Redox Regulation ◽

Chemotherapeutic Agents ◽

Tyrosyl Radical ◽

Compound I ◽

Definitive Evidence ◽

Enhanced Production ◽

Physico Chemical

The release of cytochrome c from mitochondria during apoptosis results in the enhanced production of superoxide radicals, which are converted to H2O2 by Mn-superoxide dismutase. We have been concerned with the role of cytochrome c/H2O2 in the induction of oxidative stress during apoptosis. Our initial studies showed that cytochrome c is a potent catalyst of 2′,7′-dichlorofluorescin oxidation, thereby explaining the increased rate of production of the fluorophore 2′,7′-dichlorofluorescein in apoptotic cells. Although it has been speculated that the oxidizing species may be a ferryl-haem intermediate, no definitive evidence for the formation of such a species has been reported. Alternatively, it is possible that the hydroxyl radical may be generated, as seen in the reaction of certain iron chelates with H2O2. By examining the effects of radical scavengers on 2′,7′-dichlorofluorescin oxidation by cytochrome c/H2O2, together with complementary EPR studies, we have demonstrated that the hydroxyl radical is not generated. Our findings point, instead, to the formation of a peroxidase compound I species, with one oxidizing equivalent present as an oxo-ferryl haem intermediate and the other as the tyrosyl radical identified by Barr and colleagues [Barr, Gunther, Deterding, Tomer and Mason (1996) J. Biol. Chem. 271, 15498-15503]. Studies with spin traps indicated that the oxo-ferryl haem is the active oxidant. These findings provide a physico-chemical basis for the redox changes that occur during apoptosis. Excessive changes (possibly catalysed by cytochrome c) may have implications for the redox regulation of cell death, including the sensitivity of tumour cells to chemotherapeutic agents.

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