2,588 research outputs found
Influence of crystallographic orientation of biogenic calcite on <i>in situ</i> Mg XANES analyses
Micro X-ray absorption near-edge spectroscopy at the Mg <i>K</i>-edge is a useful technique for acquiring information about the environment of Mg<sup>2+</sup> in biogenic calcite. These analyses can be applied to shell powders or intact shell structures. The advantage of the latter is that the XANES analyses can be applied to specific areas, at high (e.g. micrometre) spatial resolution, to determine the environment of Mg<sup>2+</sup> in a biomineral context. Such in situ synchrotron analysis has to take into account the potential effect of crystallographic orientation given the anisotropy of calcite crystals and the polarized nature of X-rays. Brachiopod shells of species with different crystallographic orientations are used to assess this crystallographic effect on <i>in situ</i> synchrotron measurements at the Mg <i>K</i>-edge. Results show that, owing to the anisotropy of calcite, <i>in situ</i> X-ray absorption spectra (XAS) are influenced by the crystallographic orientation of calcite crystals with a subsequent potentially erroneous interpretation of Mg<sup>2+</sup> data. Thus, this study demonstrates the importance of crystallography for XAS analyses and, therefore, the necessity to obtain crystallographic information at high spatial resolution prior to spectroscopic analysis
Assessment of crystallographic influence on material properties of calcite brachiopods
Calcium carbonate biominerals are frequently analysed in materials science due to their abundance, diversity and unique material properties. Aragonite nacre is intensively studied, but less information is available about the material properties of biogenic calcite, despite its occurrence in a wide range of structures in different organisms. In particular, there is insufficient knowledge about how preferential crystallographic orientations influence these material properties. Here, we study the influence of crystallography on material properties in calcite semi-nacre and fibres of brachiopod shells using nano-indentation and electron backscatter diffraction (EBSD). The nano-indentation results show that calcite semi-nacre is a harder and stiffer (H {approx} 3â5 GPa; E = 50â85 GPa) biomineral structure than calcite fibres (H = 0.4â3 GPa; E = 30â60 GPa). The integration of EBSD to these studies has revealed a relationship between the crystallography and material properties at high spatial resolution for calcite semi-nacre. The presence of crystals with the c-axis perpendicular to the plane-of-view in longitudinal section increases hardness and stiffness. The present study determines how nano-indentation and EBSD can be combined to provide a detailed understanding of biomineral structures and their analysis for application in materials science
Does Size Matter in the Field?: Female Police Bodies in Online Television
The purpose of this study is to investigate how female officersâ body sizes are depicted on the TV show, âPolice Women of Broward County.â Little literature examines the mediaâs depiction of bodies belonging to women who are involved in traditionally masculine professions. However, feminist and masculinist literature, along with biophysical literature, tends to suggest that women are smaller and weaker than men or are perceived that way in society. It stands to reason that media may portray female officers this way or portray women attempting to overcome this stigma personally and professionally to appeal to viewers or as a reflection of mainstream attitudes or ideas. Using a record-review case study methodology, the researcher examined free snippets and numerous online episodes of the TLC Network show, âPolice Women of Broward County.â The show, which includes fieldwork and interviews, contained quotations about size, and scenarios in which size appeared to be relevant to policing. Overcoming the stigma was a recurring theme, but it was not the only theme. Some comments were positively associated with female officersâ sizes insofar as police seemed tenaciously motivated by their smaller stature. However, some comments that connected size, gender, and professionalism seemed to be negative or to suggest diminution. Some comments discussed size differences within the female police population but the comments were neither negative nor positive because they were merely factual or informational
An Examination of the Ideologies Underlying Nineteenth Century Scholarly Researches into the Viking Age
This thesis concerns the (more or less) systematic rehabilitation of the Viking Period, which was undertaken by a collection of poets and philologists, scholars and amateurs, from the latter half of the eighteenth century through the Victorian Era into the twentieth century. The reasons underlying their efforts were, in both the broad and the narrow sense, political. For example, William Morris was a Socialist, and he employed his knowledge of pre-Christian Scandinavian society in the development of a Socialist Utopia. Similarly, William Stubbs was an authority on the Anglo-Saxon legal system, and this enabled him to convincingly argue for the Germanic origin of the English democratic institutions. The works discussed range from crude propaganda to painstakingly accurate translations, and as such there are varying levels of subtlety in their ideological messages
An Examination of the Ideologies Underlying Nineteenth Century Scholarly Researches into the Viking Age
This thesis concerns the (more or less) systematic rehabilitation of the Viking Period, which was undertaken by a collection of poets and philologists, scholars and amateurs, from the latter half of the eighteenth century through the Victorian Era into the twentieth century. The reasons underlying their efforts were, in both the broad and the narrow sense, political. For example, William Morris was a Socialist, and he employed his knowledge of pre-Christian Scandinavian society in the development of a Socialist Utopia. Similarly, William Stubbs was an authority on the Anglo-Saxon legal system, and this enabled him to convincingly argue for the Germanic origin of the English democratic institutions. The works discussed range from crude propaganda to painstakingly accurate translations, and as such there are varying levels of subtlety in their ideological messages
- âŚ