Fabrication of Platinum-Gold Alloys in Pre-Hispanic South America: Issues of Temperature and Microstructure Control.

1990 ◽  
Vol 185 ◽  
Author(s):  
Carol A. Handwerker ◽  
Heather N. Lechtman ◽  
Ryna B. Marinenko ◽  
David S. Bright ◽  
Dale E. Newbury
Keyword(s):  
Phase Diagram ◽  
Liquid Phase ◽  
South America ◽  
Pacific Coast ◽  
Quantitative Information ◽  
Western World ◽  
South American ◽  
Gold Alloys ◽  
X Ray ◽  
Qualitative And Quantitative

AbstractPlatinum and platinum-gold metallurgy was fully developed by smiths in the Esmeraldas-Tumaco Pacific coast area of present day Ecuador and Colombia long before the arrival of Europeans in South America and centuries before platinum metallurgy became practicable in the Western world. Using gold to sinter together nuggets of native placer platinum, then alternately working and annealing the resultant solid, these South American smiths produced hard, fairly homogeneous platinum-gold alloys of a range of colors for fabrication into items of adornment, and small tools, such as needles, tweezers, awls, and fishhooks.The microstructures and compositions of sintered Pt-Au objects from La Tolita, Ecuador, and of experimentally simulated Pt-Au alloy samples were analyzed using new electron microprobe microanalysis (EPMA) techniques and data from the Pt-Au phase diagram in an effort to determine the fabrication temperatures used by Pre-Hispanic South American smiths. A comparison of EPMA results from the simulated materials with the corresponding results from the La Tolita Pt-Au objects suggests that the Pt-Au objects were never heated as high as 1100°C and probably never contained a liquid phase. As illustrated by this comparison, the qualitative and quantitative information provided by these new digital acquisition and display techniques far exceeds what conventional line scan and x-ray dot maps could provide.

An Al13Co4 phase in the Al–Cu–Co alloy system

1992 ◽  
Vol 7 (5) ◽  
pp. 1100-1103 ◽  
Author(s):  
B. Grushko ◽  
Ch. Freiburg
Keyword(s):  
Electron Microscopy ◽  
Phase Diagram ◽  
Scanning Electron Microscopy ◽  
Liquid Phase ◽  
Alloy System ◽  
Homogeneity Region ◽  
X Ray ◽  
Decagonal Phase ◽  
Scanning Electron

A part of the Al–Cu–Co phase diagram adjacent to the Al13Co4 composition was studied at 800 °C by scanning electron microscopy and x-ray diffractometry. The homogeneity region of the Al13Co4 phase was found to extend up to 6 at. % Cu. At 800 °C this phase is in equilibrium with Al(Co, Cu), Al5Co2, Al9Co2, the decagonal phase, and a liquid phase. The existence of the Y-phase and Al3Co was not confirmed at this temperature.

Vindication of Ulota pygmaeothecia (Orthotrichaceae, Bryophyta)

Phytotaxa ◽  
2017 ◽  
Vol 317 (3) ◽  
pp. 161 ◽  
Author(s):  
LAURA MUÑOZ-PUELLES ◽  
FRANCISCO LARA ◽  
VICENTE MAZIMPAKA ◽  
RICARDO GARILLETI
Keyword(s):  
South America ◽  
Light Microscope ◽  
Original Description ◽  
Distinct Species ◽  
Morphological Features ◽  
South American ◽  
Type Specimens ◽  
Southern South America ◽  
Comprehensive Review ◽  
Qualitative And Quantitative

Ulota pygmaeothecia (Müll.Hal.) Kindb. and Ulota luteola (Hook.f. & Wilson) Wijk & Margad. are two epiphytic mosses from the evergreen Magellanic rainforests of southern South America. Both mosses have been considered as distinct species since their original description, with their specific status retained following the comprehensive review by Nicolajs Malta of South American Ulota (1927). Recently the synonymization of U. pygmaeothecia and U. luteola was proposed (Wang & Jia 2016), based mainly on the similarities stated in the protologues and the study of the available type specimens of U. pygmaeothecia and U. fulvella, as the type materials of U. luteola were lost in the mail. In the present paper, all available type material for names associated with these two taxa, together with additional specimens recently collected, have been studied in depth. As a result, it has been found that both mosses show important sporophytic and gametophytic differences, both qualitative and quantitative, that allow for a precise distinction between them and they are reinstated here as distinct species. The morphological features that best differentiate U. luteola and U. pygmaeothecia are discussed and illustrated with light microscope and SEM pictures. Finally, an updated and detailed description of each species is presented.

scholarly journals Rudolf Schlechter's South-American orchids IV. Schlechter's "network": Venezuela and Colombia

Lankesteriana ◽  
2021 ◽  
Author(s):  
Carlos Ossenbach ◽  
Rudolf Jenny
Keyword(s):  
South America ◽  
Pacific Coast ◽  
South American ◽  
History Of Botany ◽  
Palabras Clave ◽  
The Pacific ◽  
History Of ◽  
Formed Part ◽  
First Time

The fourth chapter of the series about Rudolf Schlechter’s South-American orchids again presents abridged biographical information about the botanists and orchid collectors that formed part of Schlechter’s South-American network and who traveled and worked in those countries on the continent’s northern and Caribbean coasts, through Venezuela and Colombia. In the case of Colombia, we cross the isthmus of Darien and arrive for the first time on the Pacific coast of South America. As in other chapters, brief geographical and historical introductory outlines are presented for each of these countries, followed by a narrative on those orchidologists who visited the area, chronologically by the dates of their botanical collections. Keywords/Palabras clave: biography, biografía, history of botany, historia de la botánica, Orchidaceae

In situ microprobe quantitation of inorganic particle burden in paraffin sections of lung tissue

1988 ◽  
Vol 46 ◽  
pp. 990-991
Author(s):  
Jerrold L. Abraham
Keyword(s):  
Lung Tissue ◽  
Quantitative Information ◽  
Particulate Material ◽  
Paraffin Sections ◽  
Tissue Samples ◽  
Qualitative And Quantitative ◽  
The Past ◽  
Quantitative Analyses ◽  
Data Result

Inorganic particulate material of diverse types is present in the ambient and occupational environment, and exposure to such materials is a well recognized cause of some lung disease. To investigate the interaction of inhaled inorganic particulates with the lung it is necessary to obtain quantitative information on the particulate burden of lung tissue in a wide variety of situations. The vast majority of diagnostic and experimental tissue samples (biopsies and autopsies) are fixed with formaldehyde solutions, dehydrated with organic solvents and embedded in paraffin wax. Over the past 16 years, I have attempted to obtain maximal analytical use of such tissue with minimal preparative steps. Unique diagnostic and research data result from both qualitative and quantitative analyses of sections. Most of the data has been related to inhaled inorganic particulates in lungs, but the basic methods are applicable to any tissues. The preparations are primarily designed for SEM use, but they are stable for storage and transport to other laboratories and several other instruments (e.g., for SIMS techniques).

scholarly journals Pleistocene Mammals from Pampean Region (Argentina). Biostratigraphic, Biogeographic, and Environmental Implications

Quaternary ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 15
Author(s):  
José Luis Prado ◽  
María Teresa Alberdi ◽  
Jonathan Bellinzoni
Keyword(s):  
South America ◽  
The State ◽  
Historical Study ◽  
South American ◽  
Environmental Implications ◽  
Sedimentary Sequences ◽  
Pampean Region ◽  
Mammalian Faunas ◽  
Pleistocene Mammals ◽  
Fossil Records

The Pampean Region contains sedimentary sequences with abundant mammal fossil records, which constitute the chronological outline of the Plio–Pleistocene of South America. These classic localities have been used for more than a century to correlate with other South American regions. Throughout this time, a series of misinterpretations have appeared. To understand the stratigraphic significance of these localities and the geochronological situation of each unit referring to the Pleistocene, a critical historical study of the antecedents was carried out, evaluating the state of each unit. The biostratigraphic studies of the Pampean Region’s mammalian faunas improved the understanding of biogeographic changes taking into account the environmental fluctuations of the Pleistocene.

scholarly journals An Overview of Equine Influenza in South America

Viruses ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 888
Author(s):  
Cecilia Olguin-Perglione ◽  
María Edith Barrandeguy
Keyword(s):  
South America ◽  
Disease Surveillance ◽  
Economic Losses ◽  
South American ◽  
Respiratory Pathogens ◽  
Equine Influenza Virus ◽  
Equine Influenza ◽  
Vaccine Manufacturer ◽  
Gene Level ◽  
Control Procedures

Equine influenza virus (EIV) is one of the most important respiratory pathogens of horses as outbreaks of the disease lead to significant economic losses worldwide. In this review, we summarize the information available on equine influenza (EI) in South America. In the region, the major events of EI occurred almost in the same period in the different countries, and the EIV isolated showed high genetic identity at the hemagglutinin gene level. It is highly likely that the continuous movement of horses, some of them subclinically infected, among South American countries, facilitated the spread of the virus. Although EI vaccination is mandatory for mobile or congregates equine populations in the region, EI outbreaks continuously threaten the equine industry. Vaccine breakdown could be related to the fact that many of the commercial vaccines available in the region contain out-of-date EIV strains, and some of them even lack reliable information about immunogenicity and efficacy. This review highlights the importance of disease surveillance and reinforces the need to harmonize quarantine and biosecurity protocols, and encourage vaccine manufacturer companies to carry out quality control procedures and update the EIV strains in their products.

scholarly journals Synthesis and Na+ Ion Conductivity of Stoichiometric Na3Zr2Si2PO12 by Liquid-Phase Sintering with NaPO3 Glass

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3790
Author(s):  
Yongzheng Ji ◽  
Tsuyoshi Honma ◽  
Takayuki Komatsu
Keyword(s):  
Solid State ◽  
Liquid Phase ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
Ion Conductivity ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Sintering Time ◽  
Lower Activation

Sodium super ionic conductor (NASICON)-type Na3Zr2Si2PO12 (NZSP) with the advantages of the high ionic conductivity, stability and safety is one of the most famous solid-state electrolytes. NZSP, however, requires the high sintering temperature about 1200 °C and long sintering time in the conventional solid-state reaction (SSR) method. In this study, the liquid-phase sintering (LPS) method was applied to synthesize NZSP with the use of NaPO3 glass with a low glass transition temperature of 292 °C. The formation of NZSP was confirmed by X-ray diffraction analyses in the samples obtained by the LPS method for the mixture of Na2ZrSi2O7, ZrO2, and NaPO3 glass. The sample sintered at 1000 °C for 10 h exhibited a higher Na+ ion conductivity of 1.81 mS/cm at 100 °C and a lower activation energy of 0.18 eV compared with the samples prepared by the SSR method. It is proposed that a new LPE method is effective for the synthesis of NZSP and the NaPO3 glass has a great contribution to the Na+ diffusion at the grain boundaries.

scholarly journals Integrated quantitative PIXE analysis and EDX spectroscopy using a laser-driven particle source

2021 ◽  
Vol 7 (3) ◽  
pp. eabc8660
Author(s):  
F. Mirani ◽  
A. Maffini ◽  
F. Casamichiela ◽  
A. Pazzaglia ◽  
A. Formenti ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Materials Science ◽  
Quantitative Information ◽  
Pixe Analysis ◽  
Materials Analysis ◽  
Particle Source ◽  
X Ray ◽  
Analysis Techniques ◽  
Sample Structure ◽  
Elemental Characterization

Among the existing elemental characterization techniques, particle-induced x-ray emission (PIXE) and energy-dispersive x-ray (EDX) spectroscopy are two of the most widely used in different scientific and technological fields. Here, we present the first quantitative laser-driven PIXE and laser-driven EDX experimental investigation performed at the Centro de Láseres Pulsados in Salamanca. Thanks to their potential for compactness and portability, laser-driven particle sources are very appealing for materials science applications, especially for materials analysis techniques. We demonstrate the possibility to exploit the x-ray signal produced by the co-irradiation with both electrons and protons to identify the elements in the sample. We show that, using the proton beam only, we can successfully obtain quantitative information about the sample structure through laser-driven PIXE analysis. These results pave the way toward the development of a compact and multifunctional apparatus for the elemental analysis of materials based on a laser-driven particle source.

Transient liquid phase bonding of Cu and Al using metallic particles interlayers

2021 ◽  
pp. 095440542098823
Author(s):  
Alireza Zaheri ◽  
Mohammadreza Farahani ◽  
Alireza Sadeghi ◽  
Naser Souri
Keyword(s):  
Liquid Phase ◽  
Mechanical Test ◽  
Transient Liquid Phase ◽  
Transient Liquid Phase Bonding ◽  
Joint Interface ◽  
Test Results ◽  
X Ray Diffraction ◽  
X Ray ◽  
Metallic Particles ◽  
Powder Interlayer

The bonding strength, and microstructures of Cu and Al couples using metallic powders as interlayer during transient liquid phase bonding (TLP bonding) were investigated. The interfacial morphologies and microstructures were studied by scanning electron microscopy equipped with energy dispersive X-ray spectroscopy, and X-ray diffraction. First, to explore the optimum bonding time and temperature, nine samples were bonded without interlayers in a vacuum condition. Mechanical test results indicated that bonding at 560°C in 20 min returns the highest bond strength (84% of Al). This bonding condition was used to join ten samples with powder interlayers. Powders were prepared by mixing different combinations of Cu, Al (+Fe nanoparticles) and Zn. In the bonding zone, different Cu9Al4, CuAl, and CuAl2 intermetallic co-precipitate. The strongest bonding is formed in the sample with the 70Al (+Fe)-30Cu powder interlayer. Powder interlayers present thinner and more uniform intermetallic layers at the joint interface.

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