scholarly journals 14C and 18O in Siberian Syngenetic Ice-Wedge Complexes

Radiocarbon ◽  
1997 ◽  
Vol 40 (2) ◽  
pp. 883-893 ◽  
Author(s):  
Yurij K. Vasil'Chuk ◽  
Alla C. Vasil'Chuk
Keyword(s):  
Cross Sections ◽  
Organic Materials ◽  
Ice Wedge ◽  
Permafrost Sediments

We discuss the possibility of dating ice wedges by the radiocarbon method. We show as an example the Seyaha, Kular and Zelyony Mys ice wedge complexes, and investigated various organic materials from permafrost sediments. We show that the reliability of dating 18O variations from ice wedges can be evaluated by comparison of different organic materials from host sediments in the ice wedge cross sections.

scholarly journals AMS 14C Dating of Pollen Concentrate from Late Pleistocene ICE Wedges From the Bison and Seyaha Sites in Siberia

Radiocarbon ◽  
2005 ◽  
Vol 47 (2) ◽  
pp. 243-256 ◽  
Author(s):  
Alla Vasil'chuk ◽  
Jong-Chan Kim ◽  
Yurij Vasil'chuk
Keyword(s):  
Late Pleistocene ◽  
Cross Sections ◽  
Regional Scale ◽  
Yamal Peninsula ◽  
14C Dating ◽  
Radiocarbon Dates ◽  
Pollen Rain ◽  
Ice Wedge ◽  
Pollen And Spores ◽  
Permafrost Sediments

Accelerator mass spectrometry (AMS) radiocarbon dates of pollen concentrate were obtained from multistage syngenetic ice wedges of cross-sections from the Late Pleistocene Bison site, located along the Lower Kolyma River (68°34'N, 158°34'E), from ∼43,600 to ∼26,200 BP, and 3 AMS 14C dates of pollen concentrate in ice wedges from the Seyaha site cross-section, located on the east coast of the Yamal Peninsula (70°10'N, 72°34'E), from ∼22,400 to ∼25,200 BP. Pollen concentrate samples were prepared using a special pretreatment procedure. Pollen and spores from ice-wedge ice signalize a regional pollen rain. Therefore, 14C-dated extracts of pollen and spores from ice-wedge ice enable an adequate reconstruction and chronology of landscape dynamics on a regional scale. The pollen and spores were well preserved despite numerous redepositions in the penecontemporaneous structure in which they were found. Thus, a comparison with dates on other fractions from the same sample is necessary. The youngest date is the most reliable among the intersample AMS 14C dates from the ice and permafrost sediments.

scholarly journals Strategy of valid <sup>14</sup>C dates choice in syngenetic permafrost

2014 ◽  
Vol 8 (6) ◽  
pp. 5589-5621 ◽  
Author(s):  
Y. K. Vasil'chuk ◽  
A. C. Vasil'chuk
Keyword(s):  
Cross Sections ◽  
Organic Material ◽  
Radiocarbon Dating ◽  
Organic Materials ◽  
Present Position ◽  
Radiocarbon Dates ◽  
Lena River ◽  
Younger Age ◽  
Selection For ◽  
Kolyma River

Abstract. The main problem of radiocarbon dating within permafrost is the uncertain reliability of the 14C dates. Syngenetic sediments contain allochthonous organic deposit that originated at a distance from its present position. Due to the very good preservation of organic materials in permafrost conditions and numerous re-burials of the fossils from ancient deposits into younger ones the dates could be both younger and older than the true age of dated material. The strategy for the most authentic radiocarbon date selection for dating of syncryogenic sediments is considered taking into account the fluvial origin of the syngenetic sediments. The re-deposition of organic material is discussed in terms of cyclic syncryogenic sedimentation and also the possible re-deposition of organic material in subaerial-subaqueous conditions. The advantages and the complications of dating organic micro-inclusions from ice wedges by the accelerator mass spectrometry (AMS) method are discussed applying to true age of dated material search. Radiocarbon dates of different organic materials from the same samples are compared. The younger age of the yedoma from cross-sections of Duvanny Yar in Kolyma River and Mamontova Khayata in the mouth of Lena River is substantiated due to the principle of the choice of the youngest 14C date from the set.

scholarly journals Syngenetic and cyclical yedoma strata of Northern Yakutia

2020 ◽  
pp. 34-64
Author(s):  
Yurij Kirillovich Vasil'chuk
Keyword(s):  
Cross Sections ◽  
Sandy Loam ◽  
River Valley ◽  
Approximate Determination ◽  
Ice Wedge ◽  
The Subject

This article demonstrates the evolution of representation on syngenetic formation of frozen strata set by Lopatin, Abolin, Leffingwell and Nekipelov. It is&nbsp;underlined that the theory of syngenesis is substantiated by the works of Gallwitz, Popov and Katasonov. It is mentioned that Dostovalov proposed a method for approximate determination of the age of ice-wedge ice and calculated that 3m wide ice wedges in the vicinity of Abalakh Lake are older than 2160 years, and 30-40 m high ice wedges in the Novosibirsk islands are older than 12,000 years according to Dostovalov&rsquo;s calculations. The subject of the detailed study is the meso- and macro- cycles in the structure of yedoma strata in Northern Yakutia. Mesocycles in the yedoma strata of the Zelyony Mys, Stanchikovsky Yar, and Batagay have been examined, along with macrocycles of the Batagay yedoma. The mesocyclicity of the cryolithogenic strata is analyzed in the following&nbsp;cross sections: in Bolshoy Lyakhovsky Island, yedoma in the Belyanka River valley, in the outcrop Soplivaya Gora in the Yana River valley, in the valley of the Vilyuy River downstream of Verkhnevilyuysk, etc. The duration of the mesocycles formation in the yedoma strata of the&nbsp;Northern Yakutia is established: a. One subaquatic-subaerial mesocycle in the Zelyony Mys yedoma consisting of a subaquatic sandy loam and a subaerial peaty horizon of 4 m thick accumulated over the period 3,000years. b. One subaquatic-subaerial mesocycle in the Stanchikovsky Yar yedoma 5 m thick accumulated over the period of 3,300 years. c. One mesocycle in the section Soplivaya Gora, in the Yana River valley with a capacity of 3 m formed for about 3.000 years. Three macrocycles are identified in the Batagay section, with capacity of 7, 10 and 40 m; the time of formation of each macrocycle varied from 15-20 to 40&nbsp;thousand years&nbsp;or more.

Cross-Section and Staining-Based Techniques for Investigating Organic Materials in Painted and Polychrome Works of Art: A Review

2012 ◽  
Vol 18 (4) ◽  
pp. 860-875 ◽  
Author(s):  
Irina Crina Anca Sandu ◽  
Stephan Schäfer ◽  
Donata Magrini ◽  
Susanna Bracci ◽  
Cecilia A. Roque
Keyword(s):  
Optical Microscopy ◽  
Cross Section ◽  
Cross Sections ◽  
Organic Materials ◽  
Specific Staining ◽  
Routine Diagnostics ◽  
Conservation Practice ◽  
Advantages And Disadvantages ◽  
New Directions ◽  
Staining Techniques

AbstractThe article presents a review of the use of cross-section and staining techniques for investigating natural organic materials (mainly proteinaceous and oil-based binders/varnishes) in painted and polychrome artworks, considering the requirements of conservation practice and routine diagnostics. The reviewed literature calls attention to the importance of using cross sections to prepare samples for optical microscopy and to different properties of embedding resins; the most appropriate instrumental conditions for optical microscopy; and the advantages and disadvantages of the most common staining techniques. A few case studies were selected to illustrate the use of autofluorescence (intrinsic fluorescence) and induced fluorescence (using specific staining tests and fluorophore-labeled antibodies) for mapping and identifying organic paint materials in cross sections. New directions of research in cross-section analyses and fluorescence-based techniques for the identification and mapping of artistic materials are presented. The complementary use of different stains on the same cross section, further exploration of intrinsic and induced fluorescence of aged versus fresh materials, and applicability of cross-section observation and staining as complementary methods for assessing the effectiveness of restoration treatments, such as cleaning and consolidation, are discussed in the last section of the article.

Growth of Single-Crystalline Tris-(8-Hydroxyquinoline) Gallium Uniform Sub-Microrods and their Optical Properties

2017 ◽  
Vol 898 ◽  
pp. 1817-1823
Author(s):  
Cheng Hu Dai ◽  
Zhi Xian Wei ◽  
Zhi Yong Pang ◽  
Sheng Hao Han
Keyword(s):  
Optical Properties ◽  
Absorption Spectrum ◽  
Cross Sections ◽  
Organic Materials ◽  
Energy Gap ◽  
Blue Shift ◽  
Molecular Packing ◽  
Single Crystalline ◽  
One Dimensional ◽  
Α Phase

One dimensional (1-D) organic materials have a bright prospect in the field of optoelectronics. Intrigued by these, 1-D uniform sub-micrometer tris-(8-hydroxyquinoline) gallium (GaQ3) rods were prepared with surfactant by an extremely facial method. The GaQ3 rods with hexagonal cross sections had excellent crystallinity and optical properties. The measurement of the absorption spectrum showed that there was an obvious blue shift comparing with the GaQ3 film. This can be explained by that the molecular packing in the α-phase rods has a looser interligand spacing compared with the GaQ3 film, consequently resulting in reduced orbital overlap and larger energy gap.

Analysis of STEM micrographs of thick objects

1978 ◽  
Vol 36 (2) ◽  
pp. 106-107
Author(s):  
S. Golladay
Keyword(s):  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Mass Distribution ◽  
Cross Sections ◽  
Phase Contrast ◽  
Image Point ◽  
Contrast Effects ◽  
Total Cross Sections ◽  
Elastic And Inelastic Scattering

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.

Direct Observation of Heat Exchanger Deposits by Cross Sectioning

1967 ◽  
Vol 25 ◽  
pp. 364-365
Author(s):  
R. W. Anderson ◽  
D. L. Senecal
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Heat Exchanger ◽  
Direct Observation ◽  
Cross Sections ◽  
Preparation Method ◽  
Specimen Preparation ◽  
Flowing Water ◽  
Transmission Electron ◽  
Deposit Layer

A problem was presented to observe the packing densities of deposits of sub-micron corrosion product particles. The deposits were 5-100 mils thick and had formed on the inside surfaces of 3/8 inch diameter Zircaloy-2 heat exchanger tubes. The particles were iron oxides deposited from flowing water and consequently were only weakly bonded. Particular care was required during handling to preserve the original formations of the deposits. The specimen preparation method described below allowed direct observation of cross sections of the deposit layers by transmission electron microscopy.The specimens were short sections of the tubes (about 3 inches long) that were carefully cut from the systems. The insides of the tube sections were first coated with a thin layer of a fluid epoxy resin by dipping. This coating served to impregnate the deposit layer as well as to protect the layer if subsequent handling were required.

Application of Improved Voltage Compensation in the SEM to Imaging of Organic Materials

1973 ◽  
Vol 31 ◽  
pp. 444-445
Author(s):  
P.J. Killingworth ◽  
M. Warren
Keyword(s):  
Electron Beam ◽  
Organic Materials ◽  
Operating Parameters ◽  
Low Density ◽  
Beam Diameter ◽  
Incident Electron Beam ◽  
Specimen Material ◽  
Voltage Compensation ◽  
Selection Of ◽  
Scanning Electron

Ultimate resolution in the scanning electron microscope is determined not only by the diameter of the incident electron beam, but by interaction of that beam with the specimen material. Generally, while minimum beam diameter diminishes with increasing voltage, due to the reduced effect of aberration component and magnetic interference, the excited volume within the sample increases with electron energy. Thus, for any given material and imaging signal, there is an optimum volt age to achieve best resolution.In the case of organic materials, which are in general of low density and electric ally non-conducting; and may in addition be susceptible to radiation and heat damage, the selection of correct operating parameters is extremely critical and is achiev ed by interative adjustment.

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