Thorium in crandallite-group minerals: an example from a Devonian bauxite deposit, Timan, Russia

2004 ◽  
Vol 68 (3) ◽  
pp. 489-497 ◽  
Author(s):  
L. E. Mordberg
Keyword(s):  
Crystal Lattice ◽  
Radiation Damage ◽  
Mineral Composition ◽  
Bauxite Deposit ◽  
Weathering Profile ◽  
Silicate Mineral ◽  
Fe Content ◽  
Very High ◽  
Type Substitution ◽  
Simplified Formula

AbstractA Th-rich mineral of the crandallite group has been investigated from the weathering profile of the Schugorsk bauxite deposit, Timan, Russia. It occurs within thin (up to 0.5 mm) organic-rich veinlets together with ‘leucoxene’ in the form of small shapeless grains which vary in size from 1—2 mm to 60—70 mm. Rare grains disseminated among boehmite crystals were also found. Microprobe analyses determined that the ThO2 content can be as high as 18 wt.%. The mineral composition is intermediate between crandallite CaAl3H(PO4)2(OH)6, goyazite SrAl3H(PO4)2(OH)6, Th-crandallite and svanbergite SrAl3PO4SO4(OH)6 in the beudantite group.Comparatively high contents of Fe and Si and a very high positive Th and Fe content correlation (r = +0.98) suggest that the formula of the hypothetical Th-bearing end-member is ThFe3(PO4,SiO4)2(OH)6 with Th and Si substituting for REE and Prespectively (woodhouseite-type substitution). Another possible substitution is Th4+ + Ca2+ ⇋ 2REE3+ (florencite-type). A deficiency of cations in the X site can be explained by either the presence of carbon, undetectable by microprobe, in the crystal lattice or a lack of X-site cations due to radiation damage induced by Th. Some excess of cations in the B site (Al and Fe3+) can be explained by the presence of very small boehmite and hematite inclusions on the crandallite grain surfaces. Th-rich crandallite may be the result of alteration of an unidentified silicate mineral from the parent rock with a composition close to the simplified formula Fe2+ThSiO4(OH)2.

Observation of multiple Bragg reflections accompanying forbidden Si(002) reflection in bent-perfect Si crystal

2021 ◽  
pp. 1-6
Author(s):  
P. Mikula ◽  
M. Vrána ◽  
J. Šaroun ◽  
V. Ryukhtin
Keyword(s):  
High Resolution ◽  
Crystal Lattice ◽  
Perfect Crystal ◽  
Monochromatic Beam ◽  
Very High

Strong multiple Bragg reflections (MBRs) which can be realized in a bent-perfect-crystal (BPC) slab provide a monochromatic beam of excellent resolution parameters. For identifying MBR effects in the BPC Si crystal, we used the method of azimuthal rotation of the crystal lattice around the scattering vector of the primary forbidden Si(200) reflection for a fixed chosen wavelength. In this paper, several azimuthal scans searching strong MBR effects with the intention of a possible practical exploitation for very high-resolution diffractometry are presented.

scholarly journals Soil Nutrient Status of Brahmaputra Floodplain Area in Tangail Sadar Upazila for Agricultural Uses

2016 ◽  
Vol 8 (2) ◽  
pp. 11-14
Author(s):  
MAM Hossen ◽  
SA Lira ◽  
MY Mia ◽  
AKMM Rahman
Keyword(s):  
Soil Nutrient ◽  
Nutrient Status ◽  
Available Phosphorus ◽  
Soil Nutrient Status ◽  
Fe Content ◽  
P Content ◽  
Zn Content ◽  
Floodplain Area ◽  
Very High ◽  
Brahmaputra Floodplain

Soil samples from high land, medium high land, medium low land and low land of Brahmaputra Floodplain area showed that pH of the soils were slightly acidic; organic matter (OM) content was medium; total nitrogen (N), available potassium (K) and boron (B) content were low; available phosphorus (P) content was very low; available sulfur (S) and calcium (Ca) content were medium to very high; magnesium (Mg) and zinc (Zn) content were low to optimum; copper (Cu), manganese (Mn) and iron (Fe) content were very high suggesting the fact that soils of this area is moderately suitable for agricultural uses.J. Environ. Sci. & Natural Resources, 8(2): 11-14 2015

The Plastic Resistance of Crystals

1960 ◽  
Vol 13 (2) ◽  
pp. 327 ◽  
Author(s):  
JJ Gilman
Keyword(s):  
Radiation Damage ◽  
Dislocation Motion ◽  
Dislocation Velocity ◽  
Direct Observations ◽  
Very High

Evidence is presented in this paper to show that crystals present a pla8tic 'resistarwe to dislocation motion. This has been demonstrated by direct observations of dislocations in LiF crystals by Johnston and Gilman, and in Fe-Si crystals by Stein and Low. The plastic resistance is almost independent of dislocation velocity except at very high velocities. It is, however, strongly influenced by temperature, impurities, and radiation damage. In LiF crystals, the plastic resistance is much higher for glide on {100} planes than on {nO} planes.

Extremely Light Weight Rheocast Components for Automotive Space Frame

2012 ◽  
Vol 192-193 ◽  
pp. 545-550 ◽  
Author(s):  
Mario Rosso ◽  
Ildiko Peter ◽  
Gianluigi Chiarmetta ◽  
Ivano Gattelli
Keyword(s):  
High Performance ◽  
Mechanical Tests ◽  
Standard Samples ◽  
Fe Content ◽  
Wide Range ◽  
Automotive Parts ◽  
Fracture Surface Analysis ◽  
High Level ◽  
Non Destructive ◽  
Very High

This paper presents an analysis of a new rheocasting process suitable for the manufacturing of high performance automotive parts. The process is able for the realization of components using Al alloys. An important aspect is related to the possibility to obtain quite wide range of thicknesses, starting from 2.5 mm. The used alloy is the well known A356, with low Fe content, maximum 0.08 wt%. T6 heat treatments has been performed, while the soundness of the parts has been certified by non destructive tests. These parts are produced to be mounted on a top level and famous sport car. Non standard samples for mechanical tests have been machined directly from the components. Following the mechanical tests fracture surface analysis has been carried out by SEM to observe some morphological details and to evaluate the influence of the process and of the alloy conditions on the fracture behaviour. On the polished transverse sections of the samples morphological analysis has been performed. The obtained results shown high level of mechanical strength for all series of components. The reliability of the process is very high at a convenient level of manufacturing rate. The weldability of the parts has been demonstrated.

scholarly journals An Iron Transporter Is Involved in Iron Homeostasis, Energy Metabolism, Oxidative Stress, and Metacyclogenesis in Trypanosoma cruzi

2022 ◽  
Vol 11 ◽  
Author(s):  
Claudia F. Dick ◽  
Nathália Rocco-Machado ◽  
André L. A. Dos-Santos ◽  
Luiz F. Carvalho-Kelly ◽  
Carolina L. Alcantara ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Metabolic Pathways ◽  
Iron Homeostasis ◽  
Optimal Growth ◽  
Limited Information ◽  
Fe Content ◽  
Fe Uptake ◽  
And Storage ◽  
Regular Medium ◽  
Very High

The parasite Trypanosoma cruzi causes Chagas’ disease; both heme and ionic Fe are required for its optimal growth, differentiation, and invasion. Fe is an essential cofactor in many metabolic pathways. Fe is also harmful due to catalyzing the formation of reactive O2 species; for this reason, all living systems develop mechanisms to control the uptake, metabolism, and storage of Fe. However, there is limited information available on Fe uptake by T. cruzi. Here, we identified a putative 39-kDa Fe transporter in T. cruzi genome, TcIT, homologous to the Fe transporter in Leishmania amazonensis and Arabidopsis thaliana. Epimastigotes grown in Fe-depleted medium have increased TcIT transcription compared with controls grown in regular medium. Intracellular Fe concentration in cells maintained in Fe-depleted medium is lower than in controls, and there is a lower O2 consumption. Epimastigotes overexpressing TcIT, which was encountered in the parasite plasma membrane, have high intracellular Fe content, high O2 consumption—especially in phosphorylating conditions, high intracellular ATP, very high H2O2 production, and stimulated transition to trypomastigotes. The investigation of the mechanisms of Fe transport at the cellular and molecular levels will assist in elucidating Fe metabolism in T. cruzi and the involvement of its transport in the differentiation from epimastigotes to trypomastigotes, virulence, and maintenance/progression of the infection.

scholarly journals Mineralogy of soils with unusually high exchangeable Al from the western Amazon Region

Clay Minerals ◽  
2002 ◽  
Vol 37 (4) ◽  
pp. 651-661 ◽  
Author(s):  
J . J . Marques ◽  
W. G. Teixeira ◽  
D. G. Schulze ◽  
N. Curi
Keyword(s):  
Xrd Analysis ◽  
Amazon Region ◽  
X Ray Diffraction ◽  
Fine Silt ◽  
Size Fractions ◽  
Al Content ◽  
Fe Content ◽  
Exchangeable Al ◽  
Highly Weathered Soils ◽  
Very High

AbstractSome soils from the western Amazon region contain KCl-extractable Al contents 5 to 10 times greater than is typical for highly weathered soils containing predominantly kaolinite and gibbsite. We studied a soil sequence from the Brazilian western Amazon consisting of two Typic Udifluvents on the levee of the Javari River, one Aeric Endoaquent in the backswamp, and two Typic Hapludults on an adjacent terrace. We used wet chemical and X-ray diffraction (XRD) analysis to characterize several size fractions of the 0 to 0.2 m layer of the soils. The exchangeable Al content was very high in the Aquent and Udults (up to 180 mmolc kg–1), but the ‘total’ Fe content was low in all samples (<60 g kg–1). Smectite, vermiculite, hydroxy-interlayered smectite and kaolinite dominate the fine silt and clay fractions of all soils. The Fluvents contain illite in all size fractions and chlorite in the coarse clay and fine silt fractions. The Aquent and Udults have no chlorite, and small amounts of illite occur only in the coarse clay and fine silt fractions. Lepidocrocite was identified in the Aquent. Chlorite, which occurs in the sand, fine silt, and coarse clay fractions of the Fluvents, and pyrophyllite, which occurs in the fine silt fractions of all soils and in the coarse clay of the two Ultisols, appears to be inherited from the parent sediments. The hydroxy-interlayered 2:1 phyllosilicates that form as a result of weathering are the cause of the very high exchangeable Al contents.

scholarly journals Combined Bulk and Surface Radiation Damage Effects at Very High Fluences in Silicon Detectors: Measurements and TCAD Simulations

2016 ◽  
Vol 63 (5) ◽  
pp. 2716-2723 ◽  
Author(s):  
F. Moscatelli ◽  
D. Passeri ◽  
A. Morozzi ◽  
Roberto Mendicino ◽  
G.-F. Dalla Betta ◽  
...  
Keyword(s):  
Radiation Damage ◽  
Surface Radiation ◽  
Silicon Detectors ◽  
High Fluences ◽  
Very High ◽  
Tcad Simulations

scholarly journals Crystal structure and indicatopy significance of odikhinchaite from the Khibiny alkaline complex

2021 ◽  
Vol 4 ◽  
pp. 3-9
Author(s):  
R. K. Rastsvetaeva ◽  
◽  
N. V. Chukanov ◽  
D. V. Lisitsin ◽  
M. V. Voronin ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid Solution Series ◽  
X Ray Diffraction ◽  
Alkaline Complex ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Atomic Displacements ◽  
Fe Content ◽  
Simplified Formula

Odikhinchaite, a Sr-Mn-Nb-CO3-dominant eudialyte-group mineral from the Khibiny alkaline complex has been investigated using the methods of electron probe microanalysis, X-ray diffraction, infrared and Mössbauer spectroscopy. The crystal structure was refined to R = 3.4 % in the anisotropic approximation of atomic displacements using 3815 independent reflections with F > 3(F). The unit-cell parameters are: a = 14.2709(1), c = 30.023(1) Å, V = 5295.33(7) Å3; the space group is R3m. The simplified formula of the mineral is (Z = 3): Na11Sr3(Mn2+,Fe2+,Fe3+)Ca6Zr3Nb[Si25O72(OH)](CO3)Cl(OH,O)4. The studied sample is the second find of this rare mineral worldwide, represented by a variety with high Fe content in the M2 micro-region, belonging to the taseqite — odikhinchaite solid-solution series. The significance of odikhinchaite as an indicator of a stage corresponding to maximum Sr activity in specific ultraagpaitic pegmatites is discussed.

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