scholarly journals Obsidian Distribution of the Northern Patagonian Forest Area and Neighboring Sectors during the Late Holocene (Neuquén Province, Argentina)

2019 ◽  
Vol 5 (1) ◽  
pp. 121-136 ◽  
Author(s):  
Alberto E. Pérez ◽  
Martin Giesso ◽  
Michael D. Glascock
Keyword(s):  
Neutron Activation Analysis ◽  
National Park ◽  
Late Holocene ◽  
English Language ◽  
Analytical Techniques ◽  
X Ray ◽  
English Language Publication ◽  
Group 2 ◽  
Patagonian Forest ◽  
First Time

AbstractAnalysis of 519 obsidian artifacts (pebbles, debitage, cores and small bifaces) by nondestructive X-ray fluorescence from forests and steppes of southern Lanín National Park in the northern Patagonian Andean region, from Lácar (chemical group QU/AP), Lolog (CP-LL 1), Filo Hua-Hum (FHH), Paillakura (Pk, former unknown 1 group), Meliquina (MQ, former unknown group 2) and Yuco (YC) sources. Neutron activation analysis was applied to 29 of the artifacts. We identified for the first time the presence of obsidian from distant Covunco (PC1) in the center of Neuquén. This paper is the first English language publication of our ongoing, ten-year-long research. In accordance with previous work, but using other analytical techniques, the most frequently used sources during the late Holocene remain CP/LL 1 and Pk, here we add YC, mainly by the incorporation of new sites recently surveyed in the islands and the coast of Lake Lácar, next to its source. Another result consistent with previous work is the absence of obsidian from Mendoza and Chilean sources; therefore, we suggest these obsidians circulate just to the east and northeast, allowing us to discuss issues of human territoriality during the Late Holocene.

scholarly journals Procurement and circulation of obsidian in the province of La Pampa, Argentina

2018 ◽  
Vol 5 (2) ◽  
Author(s):  
Monica Alejandra Berón ◽  
Florencia Natalin Páez ◽  
Manuel Carrera Aizpitarte
Keyword(s):  
Neutron Activation Analysis ◽  
Activation Analysis ◽  
Neutron Activation ◽  
Late Holocene ◽  
X Ray ◽  
Second Stage ◽  
Research Areas ◽  
New Research ◽  
Two Stages ◽  
Obsidian Source

The goal of this study is to report the progress regarding the procurement and circulation of obsidian by hunter-gatherer populations during the Late Holocene in the province of La Pampa, Argentina. A total of 25 samples were analyzed in two stages; in the first stage neutron activation analysis (INAA) was used, while X-ray fluorescence (XRF) was employed in the second stage. This work adds nine archaeological samples from new sites and one from the Lihué Calel obsidian source. The results allow us to  take into account the sourcing of the obsidian which was found in archeological sites of four areas of study located in the south and east of the province. Both, the results generated in this new stage, and those previously obtained are integrated and discussed in relation to the information produced by other researchers from the region, which are consistent with the existing ones for La Pampa. They indicate that the obsidian recovered was procured from sources located in the Argentinian and Chilean Andes, as well as the pre-cordillera in the provinces of Neuquén and Mendoza. New data expands the spatial perspective of our interpretations to four new research areas: Curacó basin, Lihué Calel hills, Valles Transversales (Transversal Valleys) and Bajos sin Salida (Endorheic low areas).

Quantitation of the Lateral Orientational Order in Poly(p-Phenylene Terephthalamide) Fibers with X-ray Linear Dichroism Microscopy

1998 ◽  
Vol 4 (S2) ◽  
pp. 812-813
Author(s):  
A. P. Smith ◽  
A. Garcia ◽  
H. Ade
Keyword(s):  
Internal Structure ◽  
Orientational Order ◽  
Analytical Techniques ◽  
Polymeric Materials ◽  
Linear Dichroism ◽  
Specific Chemical ◽  
X Ray ◽  
Radial Orientation ◽  
First Time

Determination of internal structure of complex polymeric materials often requires a variety of analytical techniques. One technique that we have developed and recently employed for the first time for quantitative analysis is x-ray linear dichroism microscopy. With sensitivity to the presence and orientation of specific chemical functionalities within polymer molecules, x-ray linear dichroism microscopy provides a powerful tool to probe the internal structure of such molecules. We have used this ability to quantitatively analyze the lateral orientational order (tangential and radial orientation of transverse sections) within different grades of poly(p-phenylene terephthalamide) (Kevlar) fibers.Kevlar fibers are highly crystalline and possess a complicated internal structure that exhibits lateral radial orientation. Figure 1 shows x-ray micrographs of (a) Kevlar 149, (b) Kevlar 49 and (c) Kevlar 29 fibers imaged at a photon energy specific to the aromatic functionality.

scholarly journals The First Occurrence of Asbestiform Magnesio-Riebeckite in Schists in the Frido Unit (Pollino Unesco Global Geopark, Southern Italy)

Fibers ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 79 ◽  
Author(s):  
Salvatore Laurita ◽  
Giovanna Rizzo
Keyword(s):  
Southern Italy ◽  
Analytical Techniques ◽  
X Ray ◽  
Toxicological Studies ◽  
Xrf Scanning ◽  
First Occurrence ◽  
Micro Analysis ◽  
First Time ◽  
Index Mineral

In this paper, new mineralogical and petrographical data of asbestiform Magnesio-riebeckite from ophiolite cropping out in the Pollino Unesco Global Geopark (southern Italy) are presented. Magnesio-riebeckite schists with HP-LT index mineral assemblage recorded metamorphic events in blueschist facies in the Frido Unit. Previous toxicological studies showed that asbestiform Magnesio-riebeckite species exhibited high carcinogenicity in previous intraperitoneal injection experiments with rats. The results have been obtained using different analytical techniques such as X-ray fluorescence (XRF), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), and electron probe micro analysis (EPMA). Results show that all the samples contain fibrous Magnesio-riebeckite and/or prismatic, acicular crystals in aggregates. The concentration of elements in Magnesio-riebeckite crystals is: Na2O (4.12–6.26 wt%), MgO (8.22–10.87 wt%), FeO (19.07–23.81 wt%), SiO2 (52.05–56.06 wt%), CaO (1.12–4.53 wt%), Al2O3 (1.34–1.93 wt%), and MnO (0.10–0.34 wt%). Magnesio-riebeckite crystals are documented in the Pollino Unesco Global Geopark for the first time. For this reason, the aim of this paper is the characterization of Magnesio-riebeckite to improve the knowledge of this mineral in the studied area, because the release of fibers into the environment is dangerous for human health.

Quantitative determination of hafnium in mixtures of zirconium–hafnium hexachloro alkali compounds by neutron activation analysis and X-ray fluorescence

1983 ◽  
Vol 61 (9) ◽  
pp. 2189-2191 ◽  
Author(s):  
C. A. Pickles ◽  
G. J. Kipouros ◽  
S. N. Flengas ◽  
R. G. V. Hancock
Keyword(s):  
Neutron Activation Analysis ◽  
Activation Analysis ◽  
Neutron Activation ◽  
Quantitative Determination ◽  
Analytical Techniques ◽  
X Ray ◽  
Alkali Compounds

A procedure for the determination of Hf in both mixtures of HfCl4–ZrCl4 and A2HfCl6–A2ZrCl6, where A = Li, Na, K, Rb, or Cs, is described. The method involves conversion of the chlorocompounds into HfO2–ZrO2 mixtures and subsequent analysis by either X-ray fluorescence or neutron activation analysis. The two analytical techniques are compared with regard to accuracy and simplicity.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

Layered and ion implantation specimens as possible reference materials for the electron-probe microanalysis

1992 ◽  
Vol 50 (2) ◽  
pp. 1652-1653
Author(s):  
G. Remond ◽  
R.H. Packwood ◽  
C. Gilles ◽  
S. Chryssoulis
Keyword(s):  
Ion Implantation ◽  
Reference Materials ◽  
Analytical Techniques ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
X Ray ◽  
Spatially Resolved ◽  
Analytical Expressions ◽  
Original Approach ◽  
Depth Concentration

Merits and limitations of layered and ion implanted specimens as possible reference materials to calibrate spatially resolved analytical techniques are discussed and illustrated for the case of gold analysis in minerals by means of x-ray spectrometry with the EPMA. To overcome the random heterogeneities of minerals, thin film deposition and ion implantation may offer an original approach to the manufacture of controlled concentration/ distribution reference materials for quantification of trace elements with the same matrix as the unknown.In order to evaluate the accuracy of data obtained by EPMA we have compared measured and calculated x-ray intensities for homogeneous and heterogeneous specimens. Au Lα and Au Mα x-ray intensities were recorded at various electron beam energies, and hence at various sampling depths, for gold coated and gold implanted specimens. X-ray intensity calculations are based on the use of analytical expressions for both the depth ionization Φ (ρz) and the depth concentration C (ρz) distributions respectively.

More Christian Apocrypha

2012 ◽  
Vol 41 (3) ◽  
pp. 16-21
Author(s):  
Tony Burke
Keyword(s):  
New Testament ◽  
Old Testament ◽  
North American ◽  
English Language ◽  
Primary Sources ◽  
University Of Edinburgh ◽  
The University ◽  
First Time ◽  
Medieval Christianity

Scholars interested in the Christian Apocrypha (CA) typically appeal to CA collections when in need of primary sources. But many of these collections limit themselves to material believed to have been written within the first to fourth centuries CE. As a result a large amount of non-canonical Christian texts important for the study of ancient and medieval Christianity have been neglected. The More Christian Apocrypha Project will address this neglect by providing a collection of new editions (some for the first time) of these texts for English readers. The project is inspired by the More Old Testament Pseudepigrapha Project headed by Richard Bauckham and Jim Davila from the University of Edinburgh. Like the MOTP, the MCAP is envisioned as a supplement to an earlier collection of texts—in this case J. K. Elliott’s The Apocryphal New Testament (Oxford 1991), the most recent English-language CA collection (but now almost two decades old). The texts to be included are either absent in Elliott or require significant revision. Many of the texts have scarcely been examined in over a century and are in dire need of new examination. One of the goals of the project is to spotlight the abilities and achievements of English (i.e., British and North American) scholars of the CA, so that English readers have access to material that has achieved some exposure in French, German, and Italian collections.

Anionic and Cationic Redox Processes in β-Li2IrO3 and Their Structural Implications on Electrochemical Cycling in Li-Ion Cell

2019 ◽  
Author(s):  
Paul Pearce ◽  
Gaurav Assat ◽  
Antonella Iadecola ◽  
François Fauth ◽  
Rémi Dedryvère ◽  
...  
Keyword(s):  
Analytical Techniques ◽  
Charge Compensation ◽  
Coupling Mechanism ◽  
Redox Processes ◽  
Positive Electrodes ◽  
X Ray ◽  
Electrochemical Cycling ◽  
Li Ion ◽  
Electrochemical Instability ◽  
High Degree

The recent discovery of anionic redox as a means to increase the energy density of transition metal oxide positive electrodes is now a well established approach in the Li-ion battery field. However, the science behind this new phenomenon pertaining to various Li-rich materials is still debated. Thus, it is of paramount importance to develop a robust set of analytical techniques to address this issue. Herein, we use a suite of synchrotron-based X-ray spectroscopies as well as diffraction techniques to thoroughly characterize the different redox processes taking place in a model Li-rich compound, the tridimentional hyperhoneycomb β-Li2IrO3. We clearly establish that the reversible removal of Li+ from this compound is associated to a previously described reductive coupling mechanism and the formation of the M-(O-O) and M-(O-O)* states. We further show that the respective contributions to these states determine the spectroscopic response for both Ir L3-edge X-ray absorption spectroscopy (XAS) and X-ray photoemissions spectroscopy (XPS). Although the high covalency and the robust tridimentional structure of this compound enable a high degree of reversibile delithiation, we found that pushing the limits of this charge compensation mechanism has significant effects on the local as well as average structure, leading to electrochemical instability over cycling and voltage decay. Overall, this work highlights the practical limits to which anionic redox can be exploited and sheds some light on the nature of the oxidized species formed in certain lithium-rich compounds.<br>

Anionic and Cationic Redox Processes in β-Li2IrO3 and Their Structural Implications on Electrochemical Cycling in Li-Ion Cell

2019 ◽  
Author(s):  
Paul Pearce ◽  
Gaurav Assat ◽  
Antonella Iadecola ◽  
François Fauth ◽  
Rémi Dedryvère ◽  
...  
Keyword(s):  
Analytical Techniques ◽  
Charge Compensation ◽  
Coupling Mechanism ◽  
Redox Processes ◽  
Positive Electrodes ◽  
X Ray ◽  
Electrochemical Cycling ◽  
Li Ion ◽  
Electrochemical Instability ◽  
High Degree

The recent discovery of anionic redox as a means to increase the energy density of transition metal oxide positive electrodes is now a well established approach in the Li-ion battery field. However, the science behind this new phenomenon pertaining to various Li-rich materials is still debated. Thus, it is of paramount importance to develop a robust set of analytical techniques to address this issue. Herein, we use a suite of synchrotron-based X-ray spectroscopies as well as diffraction techniques to thoroughly characterize the different redox processes taking place in a model Li-rich compound, the tridimentional hyperhoneycomb β-Li2IrO3. We clearly establish that the reversible removal of Li+ from this compound is associated to a previously described reductive coupling mechanism and the formation of the M-(O-O) and M-(O-O)* states. We further show that the respective contributions to these states determine the spectroscopic response for both Ir L3-edge X-ray absorption spectroscopy (XAS) and X-ray photoemissions spectroscopy (XPS). Although the high covalency and the robust tridimentional structure of this compound enable a high degree of reversibile delithiation, we found that pushing the limits of this charge compensation mechanism has significant effects on the local as well as average structure, leading to electrochemical instability over cycling and voltage decay. Overall, this work highlights the practical limits to which anionic redox can be exploited and sheds some light on the nature of the oxidized species formed in certain lithium-rich compounds.<br>

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