FRANCISCAN COMPLEX STRUCTURAL ARCHITECTURE, DEPOSITIONAL AGE, AND PROVENANCE FOR WEST MT. TAMALPAIS, CA

2019 ◽  
Author(s):  
Owen A. Anfinson ◽  
◽  
David A. Bero ◽  
Loren A. Raymond ◽  
Victoria Simoneau
Keyword(s):  
Franciscan Complex ◽  
Complex Structural ◽  
Depositional Age ◽  
Structural Architecture

Inhomogeneous Strain Distribution in SiCf/SiC Coupons Under Tensile Loading

2017 ◽  
Author(s):  
Christopher D. Newton ◽  
Jonathan P. Jones ◽  
Adam L. Chamberlain ◽  
Martin R. Bache
Keyword(s):  
Mechanical Testing ◽  
Room Temperature ◽  
Ceramic Matrix Composites ◽  
Tensile Tests ◽  
Image Correlation ◽  
Failure Data ◽  
Inhomogeneous Strain ◽  
Ultimate Failure ◽  
Complex Structural ◽  
Structural Architecture

The complex structural architecture and inherent processing artefacts within ceramic matrix composites combine to induce inhomogeneous deformation and damage prior to ultimate failure. Bulk measurements of strain via extensometry or even localised strain gauging will fail to characterise such inhomogeneity when performing conventional mechanical testing on laboratory scaled coupons. The current research project has, therefore, applied digital image correlation (DIC) techniques to the room temperature axial assessment of a SiCf/SiC composite under static and ratchetted loading. As processed SiCf/SiC panels were subjected to detailed X-ray computed tomography (XCT) inspection prior to specimen extraction and subsequent mechanical testing. In situ DIC strain measurements were taken throughout the period of room temperature monotonic and ratchet style tensile tests. Contemporary acoustic emission (AE) signals were also recorded to indicate significant damage events and the onset of ultimate failure. Data from these separate monitoring techniques were correlated to indicate the sensitivity or otherwise to pre-existing artefacts within the as received CMC panels.

Detection of Strain and Damage Distribution in SiCf/SiC Mechanical Test Coupons

2018 ◽  
Author(s):  
Christopher D. Newton ◽  
J. Paul Jones ◽  
Louise Gale ◽  
Martin R. Bache
Keyword(s):  
Mechanical Test ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Fatigue Loading ◽  
Image Correlation ◽  
Matrix Composites ◽  
Macro Scale ◽  
Ultimate Failure ◽  
Complex Structural ◽  
Structural Architecture

The complex structural architecture and inherent processing artefacts within ceramic matrix composites combine to induce inhomogeneous deformation and damage prior to ultimate failure. Sophisticated mechanical characterisation is vital in support of a fundamental understanding of deformation in ceramic matrix composites. On the component scale, “damage tolerant” design and lifing philosophies depend upon laboratory assessments of macro-scale specimens, incorporating typical fibre architectures and matrix under representative stress-strain states. Bulk measurements of strain via extensometry or even localised strain gauging will fail to characterise such inhomogeneity when performing conventional mechanical testing on laboratory scaled coupons. The current research project has, therefore, applied digital image correlation (DIC), electrical resistance monitoring and acoustic emission techniques to the room and high temperature assessment of a SiCf/SiC composite under axial fatigue loading. Data from these separate monitoring techniques plus ancillary use of X-Ray computed tomography and optical inspection were correlated to monitor the onset and progression of damage during cyclic loading.

scholarly journals Non-cylindrical parasitic folding and strain partitioning during the Pan-African Lufilian orogeny in the Chambishi-Nkana Basin, Central African Copperbelt

2018 ◽  
Author(s):  
Koen Torremans ◽  
Philippe Muchez ◽  
Manuel Sintubin
Keyword(s):  
Mechanical Anisotropy ◽  
Strain Partitioning ◽  
First Order ◽  
Mechanical Stratigraphy ◽  
Central African Copperbelt ◽  
Pan African ◽  
World Class ◽  
Complex Structural ◽  
Structural Architecture ◽  
Clear Relation

Abstract. A structural analysis has been carried out along the southeast margin of the Chambishi-Nkana Basin in the Central African Copperbelt, hosting the world-class Cu-Co Nkana orebody. The geometrically complex structural architecture is interpreted to have been generated during a single NE-SW oriented compressional event, clearly linked to the Pan-African Lufilian orogeny. This progressive deformation resulted primarily in asymmetric multiscale parasitic fold assemblages, characterized by non-cylindrical NW-SE elongated, periclinal folds that strongly interfere laterally, leading to fold linkage and bifurcation. The vergence and amplitude of these folds consistently reflect their position along an inclined limb of a NW plunging megascale first-order fold. A clear relation is observed between development of parasitic folds and certain lithofacies assemblages in the Copperbelt Orebody Member, which hosts most of the ore. Differences in fold amplitude, wavelength and shape are explained by changes in mechanical stratigraphy caused by lateral lithofacies variation in ore-bearing horizons. In addition, strong differences in strain partitioning occur within the deforming basin, which is interpreted to be in part controlled by changes in mechanical anisotropy in the layered rock package. This work provides an essential backdrop to understand the influence of the Lufilian orogeny on metal mineralization and (re-)mobilization in the Copperbelt.

DETRITAL ZIRCON U-PB AGES PROVIDE CONSTRAINTS ON THE DEPOSITIONAL AGE AND STRUCTURE OF THE FRANCISCAN COMPLEX, MT. TAMALPAIS, CA

2018 ◽  
Author(s):  
Victoria Simoneau ◽  
◽  
Owen A. Anfinson ◽  
David A. Bero ◽  
Joseph Adams ◽  
...  
Keyword(s):  
Detrital Zircon ◽  
Franciscan Complex ◽  
Depositional Age

scholarly journals Non-cylindrical parasitic folding and strain partitioning during the Pan-African Lufilian orogeny in the Chambishi–Nkana Basin, Central African Copperbelt

Solid Earth ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 1011-1033
Author(s):  
Koen Torremans ◽  
Philippe Muchez ◽  
Manuel Sintubin
Keyword(s):  
Mechanical Anisotropy ◽  
Strain Partitioning ◽  
First Order ◽  
Mechanical Stratigraphy ◽  
Central African Copperbelt ◽  
Pan African ◽  
World Class ◽  
Complex Structural ◽  
Structural Architecture ◽  
Clear Relation

Abstract. A structural analysis has been carried out along the south-east margin of the Chambishi–Nkana Basin in the Central African Copperbelt, hosting the world-class copper and cobalt (Cu–Co) Nkana orebody. The geometrically complex structural architecture is interpreted to have been generated during a single NE–SW-oriented compressional event, clearly linked to the Pan-African Lufilian orogeny. This progressive deformation resulted primarily in asymmetric multiscale parasitic fold assemblages, characterised by non-cylindrical NW–SE-oriented periclinal folds that strongly interfere laterally, leading to fold linkage and bifurcation. The vergence and amplitude of these folds consistently reflect their position along an inclined limb of a NW-plunging megascale first-order fold. A clear relation is observed between the intensity of parasitic folding and the degree of shale content in the Copperbelt Orebody Member (COM), which hosts most of the ore. Differences in fold amplitude, wavelength and shape are explained by changes in mechanical stratigraphy caused by lateral lithofacies variation in ore-bearing horizons. In addition, strong differences in strain partitioning occur within the deforming basin, which is interpreted to be in part controlled by changes in mechanical anisotropy in the layered rock package. This work provides an essential backdrop to understand the influence of the Lufilian orogeny on metal mineralisation and (re-)mobilisation in the Copperbelt.

Strongly Coupled Redox-Linked Conformational Switching at the Active Site of the Non-Heme Iron-Dependent Dioxygenase, TauD

2019 ◽  
Author(s):  
Christopher John ◽  
Greg M. Swain ◽  
Robert P. Hausinger ◽  
Denis A. Proshlyakov
Keyword(s):  
Active Site ◽  
Structural Model ◽  
Heme Iron ◽  
Chemical Transformations ◽  
Experimental Conditions ◽  
Strongly Coupled ◽  
Non Heme Iron ◽  
Reversible Redox ◽  
Wide Range ◽  
Complex Structural

2-Oxoglutarate (2OG)-dependent dioxygenases catalyze C-H activation while performing a wide range of chemical transformations. In contrast to their heme analogues, non-heme iron centers afford greater structural flexibility with important implications for their diverse catalytic mechanisms. We characterize an <i>in situ</i> structural model of the putative transient ferric intermediate of 2OG:taurine dioxygenase (TauD) by using a combination of spectroelectrochemical and semi-empirical computational methods, demonstrating that the Fe (III/II) transition involves a substantial, fully reversible, redox-linked conformational change at the active site. This rearrangement alters the apparent redox potential of the active site between -127 mV for reduction of the ferric state and 171 mV for oxidation of the ferrous state of the 2OG-Fe-TauD complex. Structural perturbations exhibit limited sensitivity to mediator concentrations and potential pulse duration. Similar changes were observed in the Fe-TauD and taurine-2OG-Fe-TauD complexes, thus attributing the reorganization to the protein moiety rather than the cosubstrates. Redox difference infrared spectra indicate a reorganization of the protein backbone in addition to the involvement of carboxylate and histidine ligands. Quantitative modeling of the transient redox response using two alternative reaction schemes across a variety of experimental conditions strongly supports the proposal for intrinsic protein reorganization as the origin of the experimental observations.

Peculiarities of interaction of liquefied carbon dioxide gas with high-viscous oil. Part 4. Sedimentation of complex structural units of the heavy phase

2018 ◽  
pp. 29-39
Author(s):  
A.A. Lobanov ◽  
◽  
K.A. Schekoldin ◽  
M.A. Zvonkov ◽  
M.V. Khlan ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Structural Units ◽  
Carbon Dioxide Gas ◽  
Viscous Oil ◽  
Heavy Phase ◽  
Complex Structural
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