Microstructure and crystallography of the wall plates of the giant barnacle Austromegabalanus psittacus: a material organized by crystal growth

In biomineralization, it is essential to know the microstructural and crystallographic organization of natural hard tissues. This knowledge is virtually absent in the case of barnacles. Here, we have examined the crystal morphology and orientation of the wall plates of the giant barnacle Austromegabalanus psittacus by means of optical and electron microscopy, and electron backscatter diffraction. The wall plates are made of calcite grains, which change in morphology from irregular to rhombohedral, except for the radii and alae, where fibrous calcite is produced. Both the grains and fibres arrange into bundles made of crystallographically co-oriented units, which grow onto each other epitaxially. We call these areas crystallographically coherent regions (CCRs). Each CCR elongates and disposes its c-axis perpendicularly or at a high angle to the growth surfaces, whereas the a-axes of adjacent CCRs differ in orientation. In the absence of obvious organic matrices, this pattern of organization is interpreted to be produced by purely crystallographic processes. In particular, due to crystal competition, CCRs orient their fastest growth axes perpendicular to the growth surface. Since each CCR is an aggregate of grains, the fastest growth axis is that along which crystals stack up more rapidly, that is, the crystallographic c-axis in granular calcite. In summary, the material forming the wall plates of the studied barnacles is under very little biological control and the main role of the mantle cells is to provide the construction materials to the growth front.This research was funded by projects CGL2017-85118-P (A.G.C., A.G.-S.) and CGL2015-64683-P (A.B.R.-N.) of the Spanish Ministerio de Ciencia e Innovación, the Unidad Científica de Excelencia UCE-PP2016-05 of the University of Granada (A.G.C., A.B.R.-N.) and the Research Group RNM363 of the Junta de Andalucía (A.G.C.). N.A.L., A.G.C. and A.B.R.-N. acknowledge support from CONICYT-Chile through grant nos. FONDECYT 1140938, PCI REDES 170106 and PIA ANILLOS ACT172037, for international collaborative research.Peer reviewe

Origin of the biphase nature and surface roughness of biogenic calcite secreted by the giant barnacle Austromegabalanus psittacus

The calcite grains forming the wall plates of the giant barnacle Austramegabalanus psittacus have a distinctive surface roughness made of variously sized crystalline nanoprotrusions covered by extremely thin amorphous pellicles. This biphase (crystalline-amorphous) structure also penetrates through the crystal’s interiors, forming a web-like structure. Nanoprotrusions very frequently elongate following directions related to the crystallographic structure of calcite, in particular, the directions, which are the strongest periodic bond chains (PBCs) in calcite. We propose that the formation of elongated nanoprotrusions happens during the crystallization of calcite from a precursor amorphous calcium carbonate (ACC). This is because biomolecules integrated within the ACC are expelled from such PBCs due to the force of crystallization, with the consequent formation of uninterrupted crystalline nanorods. Expelled biomolecules accumulate in adjacent regions, thereby stabilizing small pellicle-like volumes of ACC. With growth, such pellicles become occluded within the crystal. In summary, the surface roughness of the biomineral surface reflects the complex shape of the crystallization front, and the biphase structure provides evidence for crystallization from an amorphous precursor. The surface roughness is generally explained as resulting from the attachment of ACC particles to the crystal surface, which later crystallised in concordance with the crystal lattice. If this was the case, the nanoprotrusions do not reflect the size and shape of any precursor particle. Accordingly, the particle attachment model for biomineral formation should seek new evidence.Instituto de Salud Carlos III Spanish Government CGL2017-85118-P CGL2015-64683-PUnidad Cientifica de Excelencia of the University of Granada UCE-PP2016-05Junta de Andalucía RNM363ANID-Chile FONDECYT 1140938 PCI ANID REDES 170106 PIA ANID ANILLOS ACT17203

Momento Económico (13)

En este número Temas de hoy, El desprendimiento de las paraestatales, 21 México: La coyuntura del susector paraestatal, Ramón Martínez Escamilla, 3/ Imperialismo y petróleo: una evocación de la leyenda de Transilvania, Isaac Palacios Solano, 6/ El mercado petrolero mundial y las perspectivas de recuperación de la economía mexicana, Raúl Gonzlllez Soriano, 9/ Presupuesto del D.F. para 1985: 6% menos que en 1984, Alejandro Méndez Rodriguez, 11/ El impacto de la política urbana del régimen actual en los sectores populares, Bernardo Navano y Jum Manuel Ramírez S., 1

Origin and expansion of foliated microstructure in pteriomorph bivalves

Abstract. The ultrastructure of the calcitic prisms of the prismatic shell layers of pteriomorph bivalves was examined by scanning electronic microscopy and diffraction techniques. Results indicate that the internal structure of the prisms is noticeably different among taxa. In species belonging to the families Pinnidae, Pteriidae, and Isognomonidae (Pterioida), prisms are built up with nanometric calcite crystals. On the other hand, Pectinidae, Propeamussliidae, Anomiidae (order Pectinoida) and the Ostreidae (Ostreoida) have prisms constituted by calcitic laths with micrometric size. These laths are indistinguishable from those constituting the foliated microstructure. In almost all cases, there is mineral continuity from the prisms to the underlying foliated layer, as confirmed by X-ray texture analyses. These findings corroborate a previous assumption that the foliated microstructure derived from calcitic prisms, particularly from those with internal foliated structure. The appearance of the foliated microstructure facilitated drastic mineralogical and microstructural changes in pteriomorph shells-for example, the development of rigid shell margins and the production of largely calcitic shells. Such changes have, no doubt, contributed to the evolutionary success of the groups, which have shown a pronounced diversification over time

Structural and Mössbauer study of (Sb0.70Te0.30)100-x Snx alloys with x = 0, 2.5, 5.0 and 7.5

(Sb 0.70 Te 0.30 ) 100-x Sn x alloys (with x = 0, 2.5, 5.0 and 7.5 at. %)have been synthesized and characterized in order to determine the crystalline structure and properties of materials obtained upon solidification and to extract information about the location of the Sn atom in the Sb-Te matrix. Powder X-ray diffraction (XRD)has been used to determine the crystalline structure, whereas Mössbauer spectroscopy has been utilized to determine the localization and the local structure of the Sn atom in the Sb-Te matrix through the hyperfine interactions of the 119 Sn probe with its environment. We found that Sb 70 Te 30 crystallizes in a trigonal structure belonging to P-3m1 space group, while the doping with Sn leads to structural distortions of the unit cell that can be described, for all the Sn concentrations, with the C2/m space group. The hyperfine parameters indicate that tin behaves as Sn(II)and has a slightly distorted environment. Finally, in order to extract all the information that the experimental results contain and to determine the preferential site occupied by the Sn impurities in the Sb-Te matrix, we have performed ab-initio calculations within the framework of the Density Functional Theory. The theoretical results enable us to determine the structural and electronic ground state of (Sb 0.70 Te 0.30 ) 100-x Sn x compounds and to confirm that Sn atoms substitute Sb atoms in the Sb-Te host.Fil: Rocca, Javier Alejandro. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; ArgentinaFil: Bilovol, Vitaliy. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; ArgentinaFil: Errandonea, Alfredo Mario. Universidad de Valencia; EspañaFil: Gil Rebaza, Arles Víctor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Mudarra Navarro, Azucena Marisol. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Medina Chanduvi, Hugo Harold. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Errico, Leonardo Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Arcondo, B.. Universidad Nacional del Noroeste de la Provincia de Buenos Aires; ArgentinaFil: Fontana, Marcelo. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; ArgentinaFil: Rodríguez Cuellar, O.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentina. Universidad de Buenos Aires; ArgentinaFil: Ureña, María Andrea. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentin

Life-history traits of the giant squid Architeuthis dux revealed from stable isotope signatures recorded in beaks

Peer reviewedPreprin

Nanostructure of Mouse Otoconia

Mammalian otoconia of the inner ear vestibular apparatus are calcium carbonate-containing mineralized structures critical in maintaining balance and detecting linear acceleration. The mineral phase of otoconia is calcite, which coherently diffracts X-rays much like a single-crystal. Otoconia contain osteopontin (OPN), a mineral-binding protein influencing mineralization processes in bones, teeth and avian eggshells, for example, and in pathologic mineral deposits. Here we describe mineral nanostructure and the distribution of OPN in mouse otoconia. Scanning electron microscopy and atomic force microscopy of intact and cleaved mouse otoconia revealed an internal nanostructure (∼50 nm). Transmission electron microscopy and electron tomography of focused ion beam-prepared sections of otoconia confirmed this mineral nanostructure, and identified even smaller (∼10 nm) nanograin dimensions. X-ray diffraction of mature otoconia (8-day-old mice) showed crystallite size in a similar range (73 nm and smaller). Raman and X-ray absorption spectroscopy – both methods being sensitive to the detection of crystalline and amorphous forms in the sample – showed no evidence of amorphous calcium carbonate in these mature otoconia. Scanning and transmission electron microscopy combined with colloidal-gold immunolabeling for OPN revealed that this protein was located at the surface of the otoconia, correlating with a site where surface nanostructure was observed. OPN addition to calcite growing in vitro produced similar surface nanostructure. Finally, these findings provide details on the composition and nanostructure of mammalian otoconia, and suggest that while OPN may influence surface rounding and surface nanostructure in otoconia, other incorporated proteins (also possibly including OPN) likely participate in creating internal nanostructure

18F-FDG-PET/CT Scan for Detection of Large Vessel Involvement in Giant Cell Arteritis: Arteser Spanish Registry

Background/Objectives: Imaging studies have transformed the diagnosis of large vessel vasculitis (LVV) involvement in giant cell arteritis (GCA). A positron emission tomography/computed tomography (PET/CT) scan with 18-fluorodeoxyglucose (18F-FDG) has emerged as a valuable tool for assessing LVV. We aimed to determine the utility of an 18F-FDG-PET/CT scan in detecting LVV in GCA in the ARTESER registry. Methods: The ARTESER study is a large multicenter, retrospective, longitudinal, and observational study, promoted by the Spanish Society of Rheumatology. It included patients newly diagnosed with GCA across 26 tertiary hospitals from 1 June 2013 to 29 March 2019. Patients with a diagnosis of incidental GCA were included if they fulfilled specific criteria, including the ACR 1990 criteria, positive imaging examinations, or the expert clinical opinion of investigators. Differences between patients with positive and negative 18F-FDG-PET/CT scan results were analyzed using a bivariate model. A regression model assessed associations in patients with a positive scan, and the predictive capacity of the cumulative dose of glucocorticoids (GC) on PET scan outcomes was evaluated using ROC curve analysis. Results: Out of 1675 GCA patients included in the registry, 377 met the inclusion criteria of having an 18F-FDG-PET/CT scan. The majority were diagnosed with a cranial GCA phenotype, and 65% had LVV. The thoracic aorta was the most frequently affected. Cardiovascular disease, diabetes, and older age had a negative association with a positive scan outcome. The OR for having a positive 18F-FDG-PET/CTC scan was lower as the number of days increased. Depending on the cumulative dosage of the GC, the 18F-FDG-PET/CT scan showed an AUC of 0.74, with a Youden index > 60 mg/day. Conclusions: Younger patients showed a higher probability of presenting LVV as detected by the 18F-FDG-PET/CT scan. The timing of the examination and the cumulative dosage of the GC influenced the likelihood of a positive result, with earlier tests being more likely to detect inflammation

Industrial, Collaborative and Mobile Robotics in Latin America: Review of Mechatronic Technologies for Advanced Automation

Mechatronics and Robotics (MaR) have recently gained importance in product development and manufacturing settings and applications. Therefore, the Center for Space Emerging Technologies (C-SET) has managed an international multi-disciplinary study to present, historically, the first Latin American general review of industrial, collaborative, and mobile robotics, with the support of North American and European researchers and institutions. The methodology is developed by considering literature extracted from Scopus, Web of Science, and Aerospace Research Central and adding reports written by companies and government organizations. This describes the state-of-the-art of MaR until the year 2023 in the 3 Sub-Regions: North America, Central America, and South America, having achieved important results related to the academy, industry, government, and entrepreneurship; thus, the statistics shown in this manuscript are unique. Also, this article explores the potential for further work and advantages described by robotic companies such as ABB, KUKA, and Mecademic and the use of the Robot Operating System (ROS) in order to promote research, development, and innovation. In addition, the integration with industry 4.0 and digital manufacturing, architecture and construction, aerospace, smart agriculture, artificial intelligence, and computational social science (human-robot interaction) is analyzed to show the promising features of these growing tech areas, considering the improvements to increase production, manufacturing, and education in the Region. Finally, regarding the information presented, Latin America is considered an important location for investments to increase production and product development, taking into account the further proposal for the creation of the LATAM Consortium for Advanced Robotics and Mechatronics, which could support and work on roboethics and education/R+D+I law and regulations in the Region. Doi: 10.28991/ESJ-2023-07-04-025 Full Text: PD