PRELIMINARY RADIOCARBON DATING RESULTS OF BONE SAMPLES AT THE LAC-UFF, BRAZIL

Radiocarbon ◽  
2020 ◽  
pp. 1-12
Author(s):  
Fabiana Oliveira ◽  
Kita Macario ◽  
Karolayne Silva ◽  
Bruna Pereira ◽  
Ingrid Chanca ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Radiocarbon Dating ◽  
The State ◽  
Human Bone ◽  
Archaeological Sites ◽  
Large Molecular Weight ◽  
Brazilian Soils ◽  
Bone Preservation ◽  
Zinc Reduction ◽  
Sixth International

ABSTRACT Collagen extraction depends on the state of bone preservation, and the acidity of Brazilian soils often prevents the use of this material for radiocarbon dating. When available, however, bone samples constitute very important chronological records for both archaeological sites and natural depositional sites of specific animals. The extraction of collagen was performed using two filters, the first aiming to remove insoluble contaminants, and the second, a vivaspin ultrafilter 30KD to retain large molecular weight materials. The collagen was liofilized and converted to CO2 by combustion in sealed quartz tubes with CuO and Ag. The graphite was produced by zinc reduction in independently sealed Pyrex™ tubes. In order to verify the accuracy of this protocol, we analyzed a modern bone and four previously dated fragments, including those from the Sixth International Radiocarbon Intercomparison (SIRI), and a fragment of human bone from the Amourins site, a Brazilian shellmound. The results for the known age material are in agreement with the expected and the studied sector of Amourins shellmound was dated 4100–3900 years cal BP from a chronological model performed with charcoal dating found in different stratigraphic layers. Samples were dated at the radiocarbon laboratory of Universidade Federal Fluminense (LAC-UFF) in Brazil.

Validity of Radiocarbon Dates on Terrestrial Snail Shells

1970 ◽  
Vol 35 (1) ◽  
pp. 94-100 ◽  
Author(s):  
M. A. Tamers
Keyword(s):  
Stable Isotope ◽  
Radiocarbon Dating ◽  
The State ◽  
Archaeological Sites ◽  
Radiocarbon Dates ◽  
Snail Shell ◽  
Terrestrial Snail ◽  
Different Characteristics

AbstractRadiocarbon dating of terrestrial snail shells is examined. Three groups of samples, two from archaeological sites of Venezuela and one from the state of Texas, were taken as examples. The true ages were determined from radiocarbon dates on associated charcoal, and measurements on the snail shells allowed the errors to be determined. The groups showed completely different characteristics: 15 samples from Texas all had ages falsely old, 12 specimens of one Venezuelan group produced all correct dates, and another Venezuelan type with five samples gave dates all too recent. This study defines the directions and extents of errors for each group of snail shells, permitting them to be used as relatively reliable datable objectives in excavations where better materials are not available.The possibility of correcting the radiocarbon dates using carbon-13 concentrations is considered, and 24 measurements are presented. It is concluded that more than one factor can influence the stable isotope concentrations in each case, and, therefore, carbon-13 is not useful for the improvement of the accuracy of snail shell dates.

The External Shape of Human γ GI Immunoglobulin from Crystal Sections

1971 ◽  
Vol 29 ◽  
pp. 428-429
Author(s):  
L. W. Labaw
Keyword(s):  
Molecular Weight ◽  
Sodium Phosphate ◽  
Osmium Tetroxide ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
X Ray ◽  
Large Molecular Weight ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Crystallographic Axes

Crystals of a human γGl immunoglobulin have the external morphology of diamond shaped prisms. X-ray studies have shown them to be monoclinic, space group C2, with 2 molecules per unit cell. The unit cell dimensions are a = 194.1, b = 91.7, c = 51.6Å, 8 = 102°. The relatively large molecular weight of 151,000 and these unit cell dimensions made this a promising crystal to study in the EM.Crystals similar to those used in the x-ray studies were fixed at 5°C for three weeks in a solution of mother liquor containing 5 x 10-5M sodium phosphate, pH 7.0, and 0.03% glutaraldehyde. They were postfixed with 1% osmium tetroxide for 15 min. and embedded in Maraglas the usual way. Sections were cut perpendicular to the three crystallographic axes. Such a section cut with its plane perpendicular to the z direction is shown in Fig. 1.This projection of the crystal in the z direction shows periodicities in at least four different directions but these are only seen clearly by sighting obliquely along the micrograph.

scholarly journals A New Radiocarbon Pretreatment Method for Molluscan Shell Using Density Fractionation of Carbonates in Bromoform

Radiocarbon ◽  
2010 ◽  
Vol 52 (3) ◽  
pp. 1301-1311 ◽  
Author(s):  
Christopher M Russo ◽  
Jennifer A Tripp ◽  
Katerina Douka ◽  
Thomas F G Higham
Keyword(s):  
Radiocarbon Dating ◽  
Separation Technique ◽  
Archaeological Sites ◽  
Density Fractionation ◽  
Pretreatment Method ◽  
Density Separation ◽  
Molluscan Shell ◽  
Archaeological Artifacts ◽  
Organic Remains

Coastal archaeological sites that lack organic remains for radiocarbon dating are often abundant sources of molluscan shells. As a substitute for materials such as bone and charcoal, shells can be analyzed with 14C dating to determine a site's age. Despite their being convenient, non-mobile archaeological artifacts, molluscan shells are plagued by several issues, including carbonate remodeling, in which aragonite in shells is converted to calcite as predicted by thermodynamics. We present here a carbonate density separation technique that addresses the issue of carbonate remodeling. Using a density fractionation with bromoform, aragonite concentrations are enriched in shells that have undergone significant remodeling. The technique has been applied to archaeological shells and has returned dates that are younger than those previously determined for the same shells.

scholarly journals A Revised Radiocarbon Chronology of the Aceramic Shell Midden of Ra’s Al-Hamra 6 (Muscat, Sultanate of Oman): Implication For Occupational Sequence, Marine Reservoir Age, and Human Mobility

Radiocarbon ◽  
2016 ◽  
Vol 58 (2) ◽  
pp. 383-395 ◽  
Author(s):  
Antoine Zazzo ◽  
Olivia Munoz ◽  
Emilie Badel ◽  
Irène Béguier ◽  
Francesco Genchi ◽  
...  
Keyword(s):  
Human Mobility ◽  
Human Bone ◽  
Archaeological Sites ◽  
Sultanate Of Oman ◽  
Shell Midden ◽  
Time Period ◽  
Entire Sequence ◽  
Radiocarbon Chronology ◽  
Reservoir Age ◽  
Bone Apatite

AbstractRa’s al-Hamra 6 (RH-6) is one of the earliest stratified archaeological sites along the eastern littoral of the Arabian Peninsula. This shell midden was radiocarbon dated to the 6th–5th millennium cal BC, but the majority of the dates were obtained before the advent of accelerator mass spectrometry (AMS) 14C dating and suffer from large uncertainties. In addition, most of these dates were obtained on marine and mangrove shells and required correction for local variations from the global average marine 14C reservoir age (MRA). This proved difficult because no consensus value exists for this period in the area. Recent excavations at RH-6 offered the opportunity to redate this important site in order to precisely determine its occupation history and later use as a graveyard, and establish the marine reservoir effect for this time period. Thirty-eight samples of charcoal, shells, and human bone apatite were selected for 14C dating. Bayesian modeling of the 14C dates suggests that the formation of the shell midden spanned ~1 millennium, between the mid-6th and the mid-5th millennium cal BC. Positive and consistent ΔR values were calculated throughout the entire sequence, ranging from 99±27 to 207±43 14C yr. At the beginning of the 4th millennium cal BC, RH-6 was used as a graveyard, as suggested by the 14C dating of a shell in strict association with an individual buried at the surface of the site. 14C dating of human bone apatite allowed us to calculate that 89% of this individual’s diet derived from marine resources. This finding confirms previous observations showing the overwhelming presence of marine and mangrove-dwelling species in the faunal and charcoal assemblage, and implies a low mobility, or mobility restricted to the coast for this population during the 4th millennium cal BC.

scholarly journals Association of large molecular weight proteasome 7 gene polymorphism with ankylosing spondylitis

1998 ◽  
Vol 41 (3) ◽  
pp. 560-562 ◽  
Author(s):  
A. Fraile ◽  
A. Nieto ◽  
J. Vinasco ◽  
Y. Bera�n ◽  
J. Mart�n ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Ankylosing Spondylitis ◽  
Gene Polymorphism ◽  
Large Molecular Weight

scholarly journals Radiocarbon Dating of Calcined Bones: Where Does the Carbon Come from?

Radiocarbon ◽  
2009 ◽  
Vol 51 (2) ◽  
pp. 601-611 ◽  
Author(s):  
A Zazzo ◽  
J-F Saliège ◽  
A Person ◽  
H Boucher
Keyword(s):  
Radiocarbon Dating ◽  
Tooth Enamel ◽  
Skeletal Remains ◽  
Archaeological Sites ◽  
Carbonate Content ◽  
The Past ◽  
Mineral Fraction ◽  
Different Temperatures ◽  
C Value ◽  
Paleodietary Reconstruction

Over the past decade, radiocarbon dating of the carbonate contained in the mineral fraction of calcined bones has emerged as a viable alternative to dating skeletal remains in situations where collagen is no longer present. However, anomalously low δ13C values have been reported for calcined bones, suggesting that the mineral fraction of bone is altered. Therefore, exchange with other sources of carbon during heating cannot be excluded. Here, we report new results from analyses on cremated bones found in archaeological sites in Africa and the Near East, as well as the results of several experiments aiming at improving our understanding of the fate of mineral and organic carbon of bone during heating. Heating of modern bone was carried out at different temperatures, for different durations, and under natural and controlled conditions, and the evolution of several parameters (weight, color, %C, %N, δ13C value, carbonate content, crystallinity indexes measured by XRD and FTIR) was monitored. Results from archaeological sites confirm that calcined bones are unreliable for paleoenvironmental and paleodietary reconstruction using stable isotopes. Experimental results suggest that the carbon remaining in bone after cremation likely comes from the original inorganic pool, highly fractionated due to rapid recrystallization. Therefore, its reliability for 14C dating should be seen as close to that of tooth enamel, due to crystallographic properties of calcined bones.

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