Description of large crystals of Seligmannite and Dufrenoysite

1912 ◽  
Vol 16 (76) ◽  
pp. 282-286
Author(s):  
R. H. Solly
Keyword(s):  
Large Crystal ◽  
Dolomite Rock

In the summer of 1906 some large crystals of seligmannite were found in an irregular, elongated cavity in the dolomite-rock of the Lengenbach quarry at Binn, Switzerland. Owing to their brittle nature many of them were broken when the rock was blasted, but I was in the quarry at the time and collected all the fragments. The largest crystal broke after it had been measured, and Dr. G. T. Prior's analysis II was made on portions of it, his other analysis, I, being made on measured crystal fragments found with the large crystal. The streak of the present crystals is black and inclined to purplish in colour, while that of the crystals first described by me was chocolate-coloured.

scholarly journals Strain effects on polycrystalline germanium thin films

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Toshifumi Imajo ◽  
Takashi Suemasu ◽  
Kaoru Toko
Keyword(s):  
Thin Films ◽  
Solid Phase ◽  
Growth Promotion ◽  
Large Strain ◽  
Compressive Strain ◽  
Substrate Material ◽  
Large Crystal ◽  
Solid Phase Crystallization ◽  
Strain Effects ◽  
Thin Film Devices

AbstractPolycrystalline Ge thin films have attracted increasing attention because their hole mobilities exceed those of single-crystal Si wafers, while the process temperature is low. In this study, we investigate the strain effects on the crystal and electrical properties of polycrystalline Ge layers formed by solid-phase crystallization at 375 °C by modulating the substrate material. The strain of the Ge layers is in the range of approximately 0.5% (tensile) to -0.5% (compressive), which reflects both thermal expansion difference between Ge and substrate and phase transition of Ge from amorphous to crystalline. For both tensile and compressive strains, a large strain provides large crystal grains with sizes of approximately 10 μm owing to growth promotion. The potential barrier height of the grain boundary strongly depends on the strain and its direction. It is increased by tensile strain and decreased by compressive strain. These findings will be useful for the design of Ge-based thin-film devices on various materials for Internet-of-things technologies.

Theory Of 3d Transition Metal Defects In 3C SiC

1996 ◽  
Vol 442 ◽  
Author(s):  
Harald Overhof
Keyword(s):  
Electronic Structure ◽  
Transition Metal ◽  
Electronic Properties ◽  
Crystal Field ◽  
High Spin ◽  
Crystal Field Splitting ◽  
Large Crystal ◽  
Field Splitting ◽  
Vacancy Model ◽  
The Difference

AbstractThe electronic properties of 3d transition metal (TM) defects located on one of the four different tetrahedral positions in 3C SiC are shown to be quite site-dependent. We explain the differences for the 3d TMs on the two substitutional sites within the vacancy model: the difference of the electronic structure between the carbon vacancy VC and the silicon vacancy VSi is responsible for the differences of the 3d TMs. The electronic properties of 3d TMs on the two tetrahedral interstitial sites differ even more: the TMs surrounded tetrahedrally by four Si atoms experience a large crystal field splitting while the tetrahedral C environment does not give rise to a significant crystal field splitting at all. It is only in the latter case that high-spin configurations are predicted.

Experimental and Modeling Study of the Transport of Chromium Acetate Solutions Through Carbonate Rocks

SPE Journal ◽  
2010 ◽  
Vol 15 (02) ◽  
pp. 349-367 ◽  
Author(s):  
F.. Chen ◽  
C.S.. S. McCool ◽  
D.W.. W. Green ◽  
G.P.. P. Willhite
Keyword(s):  
Chromium Concentration ◽  
Reservoir Rock ◽  
Water Production ◽  
Polymer Systems ◽  
Common System ◽  
Recovery Processes ◽  
Rate Controlled ◽  
Hydrolyzed Polyacrylamide ◽  
Dolomite Rock ◽  
Chromium Acetate

Summary Gelled polymer systems are applied to oil reservoirs to reduce water production and to increase sweep efficiencies in recovery processes. A common system consists of hydrolyzed polyacrylamide with a chromium (III) crosslinker. Transport of these chemicals through the reservoir rock is essential for a successful treatment. In carbonate reservoirs, dissolution of the carbonate raises the pH of the gelant to levels where chromium precipitates, robbing the gelant of crosslinker. The transport of chromium acetate solutions through dolomite rock material was studied by injecting various solutions through short cores and measuring Cr, Mg, and Ca concentrations and pH in the effluent. Chromium retention in the cores caused by precipitation was a rate-controlled process. A mathematical model was developed that described convection, dispersion, kinetic reactions of carbonate dissolution and chromium precipitation, and chemical equilibrium for reactions between aqueous components. Experimental data from this work and taken from literature were simulated by the model. One rate equation with one set of parameters described the steady-state values of chromium concentration exiting the cores after the breakthrough of the injected solutions.

Process Relationship in High-Stress Friction Coupled with Complex Shaped Counterbody and Friction Stir Welding Al-Mg-Sc-Zr Alloy

2022 ◽  
Vol 1049 ◽  
pp. 39-44
Author(s):  
Andrey Chumaevskii ◽  
Denis Gurianov ◽  
Anastasiya Gusarova ◽  
Anna Zykova ◽  
Aleksandr Panfilov ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Complex Shape ◽  
High Stress ◽  
Large Crystal ◽  
Friction Zone ◽  
Friction Stir ◽  
Model Research ◽  
Alloy Material ◽  
Distinguishing Features ◽  
Zr Alloy

Model research tests of plastic deformation, fragmentation and flow of aluminum alloy material of Al-Mg-Sc-Zr system under high loaded friction in pair with a steel counterbody of a complex shape and comparison of the obtained result with the structure formed by friction stir welding have been carried out. The conducted studies show that the structure formed by extrusion of the material from the friction zone and its compaction in the channel of the counterbody is, in general, close in structure to the structure formed by friction stir welding of similar material. The distinguishing features of the structure formed in the model experiments on friction include the introduction into the stirring zone of material with deformed large-crystal structure, increased grain size of the stirring zone, the presence of defects and differences in the geometry of the stirring zone.

scholarly journals Using a partial atomic model from medium-resolution cryo-EM to solve a large crystal structure

2021 ◽  
Vol 77 (1) ◽  
pp. 11-18
Author(s):  
Montserrat Fàbrega-Ferrer ◽  
Ana Cuervo ◽  
Francisco J. Fernández ◽  
Cristina Machón ◽  
Rosa Pérez-Luque ◽  
...  
Keyword(s):  
Molecular Replacement ◽  
Large Crystal ◽  
Rotation Matrices ◽  
Cryo Electron Microscopy ◽  
Partial Models ◽  
Medium Resolution ◽  
Experimental Phasing ◽  
Crystallographic Structures ◽  
Direct Use ◽  
Rotation Function

Medium-resolution cryo-electron microscopy maps, in particular when they include a significant number of α-helices, may allow the building of partial models that are useful for molecular-replacement searches in large crystallographic structures when the structures of homologs are not available and experimental phasing has failed. Here, as an example, the solution of the structure of a bacteriophage portal using a partial 30% model built into a 7.8 Å resolution cryo-EM map is shown. Inspection of the self-rotation function allowed the correct oligomerization state to be determined, and density-modification procedures using rotation matrices and a mask based on the cryo-EM structure were critical for solving the structure. A workflow is described that may be applicable to similar cases and this strategy is compared with direct use of the cryo-EM map for molecular replacement.

scholarly journals The anatomy as a tool for the identification of the bark of Pterocarpus angolensis and Terminalia sericea

2020 ◽  
Vol 7 (1) ◽  
pp. 925
Author(s):  
Teresa Quilhó ◽  
Fernanda Bessa ◽  
Ana Isabel Ribeiro-Barros ◽  
Natasha Ribeiro
Keyword(s):  
Plant Material ◽  
Light And Electron Microscopy ◽  
Secretory Cells ◽  
Correct Identification ◽  
Large Crystal ◽  
African Species ◽  
Fibre Bundles ◽  
Anatomical Features ◽  
Pterocarpus Angolensis ◽  
Crystal Cells

Pterocarpus angolensis and Terminalia sericea are two African species with medicinal potential. Despite the importance of their bark as a powerful astringent to treat various diseases it is poor described. In order to provide referential information for correct identification and standardization of the plant material, bark samples from each two species were collected and analyzed under light and electron microscopy. Some important anatomical features to identification were: the sclerenchyma tissue mostly in form of fibre-sclereids and the large secretory cells arranged in conspicuous rows or tangential bands in the conducting phloem in P. angolensis; the crystalliferous cells arranged in very regular tangential rows (druses) and the occurrence of large crystal cells near or including the tangential fibre bundles in T. sericea bark.The results obtained show that the anatomy of the bark can be used as an important subsidy in identification and standardization of the studied species contributing the scientific knowledge for more effective forms of scrutiny in preventing commercial adulteration of species.

scholarly journals Thermal Model and Optimization of a Large Crystal Detector Using a Metallic Magnetic Calorimeter

2014 ◽  
Vol 176 (5-6) ◽  
pp. 637-643 ◽  
Author(s):  
G. B. Kim ◽  
S. Choi ◽  
Y. S. Jang ◽  
H. J. Kim ◽  
Y. H. Kim ◽  
...  
Keyword(s):  
Thermal Model ◽  
Large Crystal ◽  
Metallic Magnetic Calorimeter ◽  
Magnetic Calorimeter

Strain Scan and Texture of an Anhydrite-Dolomite Rock from the Piora-Syncline (Switzerland)

2006 ◽  
Vol 524-525 ◽  
pp. 633-638
Author(s):  
Christian Scheffzük ◽  
Kurt Walther ◽  
Alexander Frischbutter ◽  
Rudolf Naumann
Keyword(s):  
Residual Strain ◽  
Textural Properties ◽  
Orthorhombic Symmetry ◽  
Small Circle ◽  
Foliation Plane ◽  
Neutron Time ◽  
Strain Stress ◽  
Dolomite Rock ◽  
Pulsed Neutron ◽  
Orientation Pattern

An anhydrite-dolomite rock was investigated in order to find correlations between intracrystalline strain and texture. The sample represents a composite rock, called Zuckerdolomit, occurring for instance in the central Alps. Zuckerdolomit may occasionally respond to mechanical impulses with a complete break down of its structure. Residual strain was scanned at the strain/stress diffractometer EPSILON-MDS and the crystallographic texture was obtained by neutron time-of-flight diffraction at the texture diffractometer SKAT at the pulsed neutron source IBR-2 in Dubna, Russia. Texture was additionally determined by the U-stage microscopy. The texture of the rock could be derived from the main constituents: anhydrite and dolomite. The anhydrite texture appears to be characterised by an orthorhombic symmetry. One plane of the symmetry trends parallel to the rock’s foliation plane, with basal planes subparallel to and a small circle distribution within the foliation plane. There is a subordinated small circle orientation pattern relating in 45° to the rock’s foliation plane. On the other hand, the subordinated regulation pattern of anhydrite is fixed to the orientation of the foliation plane. The determined residual strain data for anhydrite and dolomite reflect a generally opposed directed state, regarding both, compression and dilatation. Moreover, taking into account the elastic constants for both minerals, which differ approximately by the factor two, the special geomechanical behaviour of the studied Zuckerdolomit appears to be considerably determined by interactions between its residual strain and textural properties. This may be of particular importance for underground activities (mining, tunnelling etc.). The dangerous geomechanical behaviour of the rock seems to be determined by its residual straintexture relations more than so far believed (anhydrite hydration).

Mucopolysaccharides and the Calcification of the Scale of the Roach (Leuciscus rutilus)

1956 ◽  
Vol s3-97 (39) ◽  
pp. 329-332
Author(s):  
O. WALLIN
Keyword(s):  
Transition Zone ◽  
Great Increase ◽  
Periodic Acid ◽  
Mineral Matter ◽  
Large Crystal ◽  
Periodic Acid Schiff ◽  
Acid Mucopolysaccharides ◽  
Pas Reaction ◽  
Inorganic Fraction

1. The scale of the roach (Leuciscus rutilus L.) was examined for state of calcification, metachromasy, and reaction to the periodic acid / Schiff (PAS) test. 2. Metachromasy and a positive PAS-reaction imply acid mucopolysaccharides in the bony layer. 3. There is a great increase in these reactions and in reactions for bone salts in the transition zone between the uncalcified and calcified part of the bony layer. 4. These reactions imply that the bond between the osseoid and the inorganic fraction of the bony layer is through SO2- and PO4- groupings. 5. The fibrillary plate lacks metachromasy, but shows a positive PAS-reaction. Before calcification a strong orthochromasy points to acid groups in connexion with the collagen. Under the radii there is no orthochromasy, and the PAS-reaction is negative. 6. When calcifying, the fibrillary plate loses its orthochromasy and the mineral matter is deposited as large crystal-complexes. 7. In regenerating scales the reactions are weaker than in normal scales.

Strain Scan and Texture of an Anhydrite-Dolomite Rock from the Piora-Syncline (Switzerland)

2006 ◽  
pp. 633-638
Author(s):  
Christian Scheffzük ◽  
Kurt Walther ◽  
Alexander Frischbutter ◽  
Rudolf Naumann
Keyword(s):  
Dolomite Rock
Sign in / Sign up

Export Citation Format

Share Document