Deposition and transport of gold by thiosulphates, Veitsch, Austria

1995 ◽  
Vol 59 (395) ◽  
pp. 253-258 ◽  
Author(s):  
H. Kucha ◽  
W. Prohaska ◽  
E. F. Stumpfl
Keyword(s):  
Grain Size ◽  
Natural Environment ◽  
Direct Evidence ◽  
Average Composition ◽  
Magnesite Deposit ◽  
Primary Gold

AbstractTwo types of gold can be distinguished in tetrahedrite from the Veitsch magnesite deposit, Austria. Primary gold present in unfractured massive tetrahedrite, has a grain size up to 18 μm and contains, on average, Cu 8.73, Ag 7.01, Au 78.63 and Hg 2.35 (wt.%). Secondary gold is present in fractures and is directly intergrown with digenite, covellite, Cu-thiosulphate, cuprite and chrysocolla but not with malachite or azurite. The secondary gold is up to 200 µm in size with an average composition of Cu 3.06, Ag 6.82, Au 86.41 and Hg 3.51 (wt.%). It is usually closely intergrown with thiosulphates containing up to 0.21 wt.% Au. This, together with the presence of ‘dirty’ gold with cloudy thiosulphate inclusions, directly indicates the transport and deposition of Au by a thiosulphate ligand. We believe this is the first reported direct evidence of gold transport and deposition by thiosulphate complexes in a natural environment.

Studies with the intraruminal selenium pellet. 2. The effect of grain size of selenium on the functional life of pellets in sheep

1981 ◽  
Vol 32 (6) ◽  
pp. 935 ◽  
Author(s):  
DR Hudson ◽  
RA Hunter ◽  
DW Peter
Keyword(s):  
Grain Size ◽  
Progressive Increase ◽  
Coarse Grained ◽  
Elemental Selenium ◽  
Average Composition ◽  
Plasma Selenium ◽  
Iron Selenide ◽  
Fine Grained ◽  
Grain Sizes

Grain size of elemental selenium is a major factor controlling the long-term effectiveness of intraruminal selenium pellets. Microscope studies of polished sections of new and used selenium pellets showed that two commercially manufactured pellets contained selenium with average grain sizes about 4 and 40 �m respectively. Plasma selenium concentrations in sheep treated with pellets containing the coarse-grained selenium were maintained at higher levels over longer periods of time than those measured for sheep treated with pellets with fine-grained selenium. Pellets removed from sheep after 2, 4, 8, 16 and 28 days showed a progressive increase in the degree of alteration of selenium to a compound of average composition (g/100 g) iron, 33.7; selenium, 51.3 ; oxygen, 15.0. After 28 days only a small percentage of elemental selenium remained in pellets with fine-grained selenium, whereas about 50% remained in pellets with coarse-grained selenium. CSIRO prototype pellets, for which long-term effectiveness had been established, also contained coarse-grained selenium, and remnants of selenium were found in pellets that had been in sheep for periods up to 3 years. Selenium, administered in gelatin capsules or as sachets containing glass-selenium mixtures, was stable under the pH-Eh conditions of the rumen, but was rendered unstable in selenium pellets or iron-selenium mixtures by the presence of iron. It is probable that the most rapid release of selenium to the sheep occurs as a result of a chemical reaction involving the oxidation of iron and concomitant alteration of elemental selenium to iron selenide.

Observation of slip propagation across grain boundaries in Ni3Al

1986 ◽  
Vol 44 ◽  
pp. 864-865 ◽  
Author(s):  
I. Baker ◽  
E.M. Schulson ◽  
J.A. Horton
Keyword(s):  
Grain Size ◽  
Yield Strength ◽  
Room Temperature ◽  
Size Dependence ◽  
Direct Evidence ◽  
Specimen Preparation ◽  
Fine Grained ◽  
Room Temperature Yield Strength ◽  
Pile Up ◽  
Preparation Techniques

Recent modelling of the grain size dependence of the room-temperature yield strength of Ni3Al has invoked the concept of dislocation pile-ups. The idea is that the yield strength measured in the Liiders regime (i.e. the Liiders band propagation stress) represents not the stress to independently nucleate slip in each grain but the stress required to propagate slip through the material. This paper presents direct evidence of slip propagation from one grain to the next and thus validation of the use of a pile-up model for Ni3Al.Miniature tensile specimens (3 mm x 7 mm x0.2 mm), made from an extruded rod of fine-grained (∽10 μm) Ni3Al containing 0.35 at.% boron, were strained under tension whilst being observed in a Philips EM 430T operated at 300 KV. Details of the design and operation of the straining stage and of the specimen preparation techniques are given elsewhere.

scholarly journals KETERDAPATAN EMAS DAN PERAK DALAM SEDIMEN PERMUKAAN DASAR LAUT DI PERAIRAN BAYAH DAN CIHARA, BANTEN SELATAN

2016 ◽  
Vol 5 (3) ◽  
Author(s):  
Maman Surachman ◽  
Yudi Darlan
Keyword(s):  
Grain Size ◽  
Gold Mineralization ◽  
Fine Sand ◽  
Silty Sand ◽  
Surficial Sediments ◽  
Grain Sizes ◽  
Investigation Area ◽  
Gold Silver ◽  
Block Area ◽  
Primary Gold

Sedimen permukaan dasar laut di daerah penyelidikan lebih dari 95 % terdiri atas material sedimen klastik hasil rombakan dari batuan di daratan (terrigenous sediment). Berdasarkan teksturnya, sedimen daerah telitian dapat diklasifikasikan menjadi 4 jenis : pasir lanaun, pasir, lanau pasiran, dan pasir sedikit kerikilan. Secara lateral, pasir lanauan merupakan sedimen yang paling luas sebarannya. Berdasarkan ukuran butirannya, komposisi sedimen di daerah telitian didominasi oleh ukuran pasir halus, pasir sangat halus dan lanau. Di blok timur, kadar emas dalam sedimen berkisar antara 0,1 – 0,54 ppm, namun umumnya < 0,3 ppm. Kadar perak berkisar antara 5,62 -30,85 ppm, umumnya < 15 ppm. Di blok barat, kadar emas berkisar antara 0,11 – 0,57 ppm, namun umumnya >0,3 ppm. Kadar perak antara 7,43 – 28,35 ppm, namun umumnya > 15 ppm. Emas dan perak dalam sedimen terutama diperkirakan berasal dari mineralisasi primer yang terdapat di daerah hulu S. Cimadur dan daerah hulu S. Cihara. Kata Kunci : Emas, perak, sedimen, Bayah & Cihara. Submarine surficial sediments of the investigated area consist of more than 95 % land derived sediments. Based on textural classification the sediments are divided into 4 units: silty sand, sand, sandy slit and slightly gravelly sand. Laterally silty sand are the widest distribution. Based on grain size analyses, the composition of the sediment consists of fine sand, very fine sand and silt grain sizes. The Gold (Au) content within the sediment of the east block area ranges beetwen 0,1 – 0,54 ppm, but generally less than 0.3 ppm. The Silver (Ag) content ranges between 5,62 - 30,85 ppm, but generally less than 15 ppm. In west block area, Au content within sediment ranges between 0,11 – 0,57 ppm, but generally > 0,3 ppm. The Ag content ranges between 7,43 – 28,35 ppm, but generally > 15 ppm. The occurrence of Au and Ag within sediments of the investigation area are mainly estimated from primary gold mineralization areas which are located in upstream areas of Cimadur and Cihara Rivers. Keyword : Gold, silver, sedimen, Bayah & Cihara

Impact of exposure to a simulated predator (Mergus merganser) on the activity of juvenile Atlantic salmon (Salmo salar) in a natural environment

2002 ◽  
Vol 80 (11) ◽  
pp. 2006-2013 ◽  
Author(s):  
Mélanie Dionne ◽  
Julian J Dodson
Keyword(s):  
Grain Size ◽  
Body Size ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Natural Environment ◽  
Juvenile Salmon ◽  
Short Term ◽  
Sediment Grain Size ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon

Some laboratory studies suggest that the presence of predators influences the short-term behaviour of juvenile Atlantic salmon. However, few studies have been conducted in the natural environment to confirm these observations and to document how biological and environmental factors influence the behaviour of fish faced with a predator. Of the many potential predators of juvenile Atlantic salmon, Salmo salar, the common merganser, Mergus merganser, is a major one. This study was designed to investigate the immediate and short-term impact of exposure to a simulated avian predator on the activity of juvenile Atlantic salmon in their natural habitat. The influence of riverbed sediment grain size, a major determinant of habitat choice in salmon, and body size of juvenile salmon on the nature and intensity of their response to the predator was also investigated. Observations were made before and after exposure to a model of M. merganser in three situations: (1) fry (young salmon during their first summer of life) on fine sediment, (2) fry on coarse sediment, and (3) parr (young salmon during their second or third summer of life) on coarse sediment. Observations were also made on fry exposed to a harmless floating stimulus to evaluate if the decoys were perceived as threat. Following exposure, the feeding rate of juvenile salmon decreased by 25–39% and the moving rate increased by 123–386%. Sediment grain size influenced the nature of the immediate response of juvenile salmon, while body size influenced the intensity of the moving response. Parr moved significantly more than fry after exposure to the simulated predator.

Random isn't real: How the patchy distribution of ecological rewards may generate “incentive hope”

2019 ◽  
Vol 42 ◽  
Author(s):  
Laurel Symes ◽  
Thalia Wheatley
Keyword(s):  
Natural Environment ◽  
Random Distribution ◽  
Spatiotemporal Distribution ◽  
Patchy Distribution ◽  
Distribution Of Resources

AbstractAnselme & Güntürkün generate exciting new insights by integrating two disparate fields to explain why uncertain rewards produce strong motivational effects. Their conclusions are developed in a framework that assumes a random distribution of resources, uncommon in the natural environment. We argue that, by considering a realistically clumped spatiotemporal distribution of resources, their conclusions will be stronger and more complete.

Extreme self-sacrifice beyond fusion: Moral expansiveness and the special case of allyship

2018 ◽  
Vol 41 ◽  
Author(s):  
Daniel Crimston ◽  
Matthew J. Hornsey
Keyword(s):  
General Theory ◽  
Biological Markers ◽  
Natural Environment ◽  
Relevant Dimension ◽  
Special Case

AbstractAs a general theory of extreme self-sacrifice, Whitehouse's article misses one relevant dimension: people's willingness to fight and die in support of entities not bound by biological markers or ancestral kinship (allyship). We discuss research on moral expansiveness, which highlights individuals’ capacity to self-sacrifice for targets that lie outside traditional in-group markers, including racial out-groups, animals, and the natural environment.

Effect of Shock Loading on the Microstructure of Uniloy 326

1974 ◽  
Vol 32 ◽  
pp. 504-505
Author(s):  
K. P. Staudhammer ◽  
L. E. Murr
Keyword(s):  
Grain Size ◽  
Shock Loading ◽  
Current Investigation ◽  
Two Phase ◽  
05 C ◽  
Shock Deformation ◽  
Heat Treated

The effect of shock loading on a variety of steels has been reviewed recently by Leslie. It is generally observed that significant changes in microstructure and microhardness are produced by explosive shock deformation. While the effect of shock loading on austenitic, ferritic, martensitic, and pearlitic structures has been investigated, there have been no systematic studies of the shock-loading of microduplex structures.In the current investigation, the shock-loading response of millrolled and heat-treated Uniloy 326 (thickness 60 mil) having a residual grain size of 1 to 2μ before shock loading was studied. Uniloy 326 is a two phase (microduplex) alloy consisting of 30% austenite (γ) in a ferrite (α) matrix; with the composition.3% Ti, 1% Mn, .6% Si,.05% C, 6% Ni, 26% Cr, balance Fe.

The Immuno-Electron Microscopic Localization of the Mo-Fe Protein Component of Nitrogenase in Cells of Azotobacter Vinelandii

1973 ◽  
Vol 31 ◽  
pp. 574-575
Author(s):  
J. T. Stasny ◽  
R. C. Burns ◽  
R. W. F. Hardy
Keyword(s):  
Cellular Localization ◽  
Direct Evidence ◽  
Azotobacter Vinelandii ◽  
Intracellular Localization ◽  
Protein Component ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Fe Protein ◽  
Intracytoplasmic Membranes

Structure-functlon studies of biological N2-fixation have correlated the presence of the enzyme nitrogenase with increased numbers of intracytoplasmic membranes in Azotobacter. However no direct evidence has been provided for the internal cellular localization of any nitrogenase. Recent advances concerned with the crystallizatiorTand the electron microscopic characterization of the Mo-Fe protein component of Azotobacter nitrogenase, prompted the use of this purified protein to obtain antibodies (Ab) to be conjugated to electron dense markers for the intracellular localization of the protein by electron microscopy. The present study describes the use of ferritin conjugated to goat antitMo-Fe protein immunoglobulin (IgG) and the observations following its topical application to thin sections of N2-grown Azotobacter.

Structural similarity of ribosomes from E. coli and A. salina

1978 ◽  
Vol 36 (2) ◽  
pp. 242-243
Author(s):  
M. Boublik ◽  
R.M. Wydro ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Ribosomal Proteins ◽  
Direct Evidence ◽  
Structural Similarity ◽  
Carbon Support ◽  
Artemia Salina ◽  
Uranyl Acetate ◽  
Biological Assays ◽  
E Coli ◽  
And Function ◽  
Fine Carbon

Ribosomes are ribonucleoprotein particles necessary for processing the genetic information of mRNA into proteins. Analogy in composition and function of ribosomes from diverse species, established by biochemical and biological assays, implies their structural similarity. Direct evidence obtained by electron microscopy seems to be of increasing relevance in understanding the structure of ribosomes and the mechanism of their role in protein synthesis.The extent of the structural homology between prokaryotic and eukaryotic ribosomes has been studied on ribosomes of Escherichia coli (E.c.) and Artemia salina (A.s.). Despite the established differences in size and in the amount and proportion of ribosomal proteins and RNAs both types of ribosomes show an overall similarity. The monosomes (stained with 0.5% aqueous uranyl acetate and deposited on a fine carbon support) appear in the electron micrographs as round particles with a diameter of approximately 225Å for the 70S E.c. (Fig. 1) and 260Å for the 80S A.s. monosome (Fig. 2).

Aspects of microanalysis in a transmission electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 510-511
Author(s):  
R. Sinclair ◽  
B.E. Jacobson
Keyword(s):  
Grain Size ◽  
Electron Beam ◽  
Electron Microscope ◽  
Chemical Analysis ◽  
Transmission Electron Microscope ◽  
Vapor Deposition ◽  
Critical Currents ◽  
X Ray ◽  
Fine Grain ◽  
Transmission Electron

INTRODUCTIONThe prospect of performing chemical analysis of thin specimens at any desired level of resolution is particularly appealing to the materials scientist. Commercial TEM-based systems are now available which virtually provide this capability. The purpose of this contribution is to illustrate its application to problems which would have been intractable until recently, pointing out some current limitations.X-RAY ANALYSISIn an attempt to fabricate superconducting materials with high critical currents and temperature, thin Nb3Sn films have been prepared by electron beam vapor deposition [1]. Fine-grain size material is desirable which may be achieved by codeposition with small amounts of Al2O3 . Figure 1 shows the STEM microstructure, with large (∽ 200 Å dia) voids present at the grain boundaries. Higher quality TEM micrographs (e.g. fig. 2) reveal the presence of small voids within the grains which are absent in pure Nb3Sn prepared under identical conditions. The X-ray spectrum from large (∽ lμ dia) or small (∽100 Ǻ dia) areas within the grains indicates only small amounts of A1 (fig.3).

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