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 &lt;i&gt;K&lt;/i&gt;-edge is a useful technique for acquiring information about the environment of Mg&lt;sup&gt;2+&lt;/sup&gt; 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&lt;sup&gt;2+&lt;/sup&gt; 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 &lt;i&gt;in situ&lt;/i&gt; synchrotron measurements at the Mg &lt;i&gt;K&lt;/i&gt;-edge. Results show that, owing to the anisotropy of calcite, &lt;i&gt;in situ&lt;/i&gt; X-ray absorption spectra (XAS) are influenced by the crystallographic orientation of calcite crystals with a subsequent potentially erroneous interpretation of Mg&lt;sup&gt;2+&lt;/sup&gt; 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

Palaeoenvironmental signatures revealed from rare earth element (REE) compositions of vertebrate microremains of the Vesiku Bone Bed (Homerian, Wenlock), Saaremaa Island, Estonia

The Estonian Journal of Earth Sciences is an open access journal and applies the Creative Commons Attribution 4.0 International License CC BY to all its papers (http://creativecommons.org/licenses/by/4.0/). The attached file is the published version of the article

Oxygen isotope equilibrium in brachiopod shell fibres in the context of biological control

No abstract available

Rare earth elements (REEs) in vertebrate microremains from the upper Pridoli Ohesaare beds of Saaremaa Island, Estonia: geochemical clues to palaeoenvironment c

This is an open access article, available to all readers online, licensed under the Creative Commons Attribution 4.0 International License (CC BY; http://creativecommons.org/licenses/by/4.0/). The attached file is the published version of the article

Biogeochemical fingerprinting of magnetotactic bacterial magnetite

Data Availability. All data related to the manuscript, including samples and aspects of methodology, are included in the main manuscript or as part of SI Appendix. Requests for additional data (i.e., APT data files), details of protocols, materials, and for any questions related to the manuscript, should be addressed to the corresponding author, Dr. Alberto Pérez-Huerta ([email protected]). Original IVAS files (RHIT and HITS) data are available in Figshare (45).ACKNOWLEDGMENTS. This work is supported by NSF grants EAR-1647012 and EAR-150779 grants awarded to A.P.-H. D.A.B. is supported by NSF grant EAR-1423939. C.J.L. wishes to thank Junta de Andalucía (Spain) projects B-BIO-432-UGR20 and P20_00208 and Ministerio de Ciencia y Educación (Spain) projects PDC2021-121135-I00 and CGL 2016-76723. T.P. acknowledges support of Laboratory Directed Research and Development Program through Ames Laboratory. This work at the Ames National Laboratory was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. Electron microscopy work (FIBelectron microscopy and scanning and transmission electron microscopy imaging) was performed at the UA AARC, the Ames National Laboratory, and the Universidad de Granada. Electron microscopy imaging and FIB work in the Ames Laboratory was performed using instruments in the Sensitive Instrument Facility. The Ames National Laboratory is operated for the U.S. Department of Energy by Iowa State University under contract No. DE-AC02-07CH11358. The authors also acknowledge the work of Drs. Fernando Laiginhas and Alejandra Londoño-Calderon in FIB-scanning electron microscopy sample preparation, Dr. Matthew Lynn for help with FIB training and specimen preparation, and the invaluable assistance of Dr. Lynda Williams and Dr. Maitrayee Bose for the SIMS and nano-SIMS analyses, respectively, using instruments in the NSF-supported Multiuser Facility at Arizona State University.This article contains supporting information online at http://www.pnas.org/lookup/suppl/doi:10.1073/pnas. 2203758119/-/DCSupplemental.Biominerals are important archives of the presence of life and environmental processes in the geological record. However, ascribing a clear biogenic nature to minerals with nanometer-sized dimensions has proven challenging. Identifying hallmark features of biologically controlled mineralization is particularly important for the case of magnetite crystals, resembling those produced by magnetotactic bacteria (MTB), which have been used as evidence of early prokaryotic life on Earth and in meteorites. We show here that magnetite produced by MTB displays a clear coupled C–N signal that is absent in abiogenic and/or biomimetic (protein-mediated) nanometer-sized magnetite. We attribute the presence of this signal to intracrystalline organic components associated with proteins involved in magnetosome formation by MTB. These results demonstrate that we can assign a biogenic origin to nanometer-sized magnetite crystals, and potentially other biominerals of similar dimensions, using unique geochemical signatures directly measured at the nanoscale. This finding is significant for searching for the earliest presence of life in the Earth’s geological record and prokaryotic life on other planetsNSF grants EAR-1647012 and EAR-150779NSF grant EAR-1423939Junta de Andalucía (Spain) projects B-BIO-432-UGR20 and P20_00208Ministerio de Ciencia y Educación (Spain) projects PDC2021-121135-I00 and CGL 2016-76723Laboratory Directed Research and Development Program through Ames LaboratoryU.S. Department of Energy (DOE

O humor na estratégia de persuasão durante as campanhas eleitorais

Resumo Realiza-se uma análise do uso do humor como parte das estratégias de persuasão na liderança e na política, em geral, e nas campanhas eleitorais em particular. Aborda-se também o estudo das funções desempenhadas pelo humor nas campanhas eleitorais e as razões pelas quais este é usado como parte de estratégias para convencer os eleitores. Examinou-se também a literatura especializada e as investigações já realizadas sobre o assunto, tanto nos negócios como na política. Finalmente, concluiu-se que, sob regimes democráticos, o humor tem sido utilizado como estratégia de comunicação durante as campanhas eleitorais para gerenciar o afeto e conquistar o voto dos eleitores, procurando persuadí-los e mobilizá-los. Palavras-chave:&nbsp;Humor, estratégias de persuasão política, liderança, marketing político, campanhas eleitorais, funções do humor, sistemas democráticos, poder político. &nbsp; Abstract In this paper we analyze the use of humor as part of the strategies of persuasion in leadership and politics in general, and in election campaigns and the political marketing, in particular. It addresses also the study of the functions performed by the humor in election campaigns and the reasons why it is used as part of the strategies of persuasion of voters. We examine also the literature and research that has been done on the subject, both in business and in politics. Finally, we conclude that under democratic regimes, humor has been used as a marketing strategy during election campaigns to manage the affection and win the vote of the voters, seeking to persuade and mobilize. Keywords:&nbsp;Humor, persuasion strategies in politics, leadership, political marketing, election campaigns, humor functions, democratic systems, political power

Biomineral repair of Abalone shell apertures

The shell of the gastropod mollusc, abalone, is comprised of nacre with an outer prismatic layer that is composed of either calcite or aragonite or both, depending on the species. A striking characteristic of the abalone shell is the row of apertures along the dorsal margin. As the organism and shell grow, new apertures are formed and the preceding ones are filled in. Detailed investigations, using electron backscatter diffraction, of the infill in three species of abalone: Haliotis asinina, Haliotis gigantea and Haliotis rufescens reveals that, like the shell, the infill is composed mainly of nacre with an outer prismatic layer. The infill prismatic layer has identical mineralogy as the original shell prismatic layer. In H. asinina and H. gigantea, the prismatic layer of the shell and infill are made of aragonite while in H. rufescens both are composed of calcite. Abalone builds the infill material with the same high level of biological control, replicating the structure, mineralogy and crystallographic orientation as for the shell. The infill of abalone apertures presents us with insight into what is, effectively, shell repair