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  • 1
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    Multimodal imaging of the self-regulating developing brain (2012)
    National Academy of Sciences
    Details
    Publication Date: 2012-11-12
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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    PAPER CURRENT
  • 2
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    Long-term influence of normal variation in neonatal characteristics on human brain development (2012)
    National Academy of Sciences
    Details
    Publication Date: 2012-11-19
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 3
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    Low-temperature magnetic properties of pelagic carbonates: Oxidation of biogenic magnetite and identification of magnetosome chains (2014)
    American Geophysical Union
    Details
    Publication Date: 2021-02-17
    Description: Pelagic marine carbonates provide important records of past environmental change. We carried out detailed low-temperature magnetic measurements on biogenic magnetite-bearing sediments from the Southern Ocean (Ocean Drilling Program (ODP) Holes 738B, 738C, 689D, and 690C) and on samples containing whole magnetotactic bacteria cells. We document a range of low-temperature magnetic properties, including reversible humped low-temperature cycling (LTC) curves. Different degrees of magnetite oxidation are considered to be responsible for the observed variable shapes of LTC curves. A dipole spring mechanism in magnetosome chains is introduced to explain reversible LTC curves. This dipole spring mechanism is proposed to result from the uniaxial anisotropy that originates from the chain arrangement of biogenic magnetite, similar to published results for uniaxial stable single domain (SD) particles. The dipole spring mechanism reversibly restores the remanence during warming in LTC measurements. This supports a previous idea that remanence of magnetosome chains is completely reversible during LTC experiments. We suggest that this magnetic fingerprint is a diagnostic indicator for intact magnetosome chains, although the presence of isolated uniaxial stable SD particles and magnetically interacting particles can complicate this test. Magnetic measurements through the Eocene section of ODP Hole 738B reveal an interval with distinct magnetic properties that we interpret to originate from less oxidized biogenic magnetite and enrichment of a biogenic “hard” component. Co-occurrence of these two magnetic fingerprints during the late Eocene in the Southern Ocean indicates less oxic conditions, probably due to increased oceanic primary productivity and organic carbon burial.
    Description: Published
    Description: 6049–6065
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: pelagic carbonates ; biogenic magnetite ; rock magnetism ; environmental magnetism ; ODP ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.05. Geomagnetism::04.05.09. Environmental magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
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    Magnetic properties of sedimentary greigite (Fe3S4): an update (2011)
    American Geophysical Union
    Details
    Publication Date: 2012-02-03
    Description: Greigite (Fe3S4) is an authigenic ferrimagnetic mineral that grows as a precursor to pyrite during early diagenetic sedimentary sulfate reduction. It can also grow at any time when dissolved iron and sulfide are available during diagenesis. Greigite is important in paleomagnetic, environmental, biological, biogeochemical, tectonic, and industrial processes. Much recent progress has been made in understanding its magnetic properties. Greigite is an inverse spinel and a collinear ferrimagnet with antiferromagnetic coupling between iron in octahedral and tetrahedral sites. The crystallographic c axis is the easy axis of magnetization, with magnetic properties dominated by magnetocrystalline anisotropy. Robust empirical estimates of the saturation magnetization, anisotropy constant, and exchange constant for greigite have been obtained recently for the first time, and the first robust estimate of the low‐field magnetic susceptibility is reported here. The Curie temperature of greigite remains unknown but must exceed 350°C. Greigite lacks a low‐temperature magnetic transition. On the basis of preliminary micromagnetic modeling, the size range for stable single domain behavior is 17–200 nm for cubic crystals and 17–500 nm for octahedral crystals. Gradual variation in magnetic properties is observed through the pseudo‐single‐domain size range. We systematically document the known magnetic properties of greigite (at high, ambient, and low temperatures and with alternating and direct fields) and illustrate how grain size variations affect magnetic properties. Recognition of this range of magnetic properties will aid identification and constrain interpretation of magnetic signals carried by greigite, which is increasingly proving to be environmentally important and responsible for complex paleomagnetic records, including widespread remagnetizations.
    Description: Published
    Description: RG1002
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: greigite ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.09. Environmental magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
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    Magnetotactic bacterial abundance in pelagic marine environments is limited by organic carbon flux and availability of dissolved iron (2011)
    Elsevier B.V.
    Details
    Publication Date: 2017-04-04
    Description: Magnetotactic bacteria intracellularly biomineralize magnetite of an ideal grain size for recording palaeomagnetic signals. However, bacterial magnetite has only been reported in a few pre-Quaternary records because progressive burial into anoxic diagenetic environments causes its dissolution. Deep-sea carbonate sequences provide optimal environments for preserving bacterial magnetite due to low rates of organic carbon burial and expanded pore-water redox zonations. Such sequences often do not become anoxic for tens to hundreds of metres below the seafloor. Nevertheless, the biogeochemical factors that control magnetotactic bacterial populations in such settings are not well known. We document the preservation of bacterial magnetite, which dominates the palaeomagnetic signal throughout Eocene pelagic carbonates from the southern Kerguelen Plateau, Southern Ocean. We provide evidence that iron fertilization, associated with increased aeolian dust flux, resulted in surface water eutrophication in the late Eocene that controlled bacterial magnetite abundance via export of organic carbon to the seafloor. Increased flux of aeolian ironbearing phases also delivered iron to the seafloor, some of which became bioavailable through iron reduction. Our results suggest that magnetotactic bacterial populations in pelagic settings depend crucially on particulate iron and organic carbon delivery to the seafloor.
    Description: Published
    Description: 441-452
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Magnetotactic bacteria ; Magnetofossils ; Magnetite ; Productivity ; Iron ; Organic carbon ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.09. Environmental magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
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    Searching for single domain magnetite in the “pseudo-single-domain” sedimentary haystack: Implications of biogenic magnetite preservation for sediment magnetism and relative paleointensity determinations (2012)
    Details
    Publication Date: 2017-04-04
    Description: Magnetic hysteresis measurements of sediments have resulted in widespread reporting of “pseudo-single-domain”-like magnetic properties. In contrast, the ideal single domain (SD) properties that would be expected to be responsible for high quality paleomagnetic records are rare. Determining whether SD particles are rare or common in sediments requires application of techniques that enable discrimination among different magnetic components in a sediment. We apply a range of such techniques and find that SD particles are much more common than has been reported in the literature and that magnetite magnetofossils (the inorganic remains of magnetotactic bacteria) are widely preserved at depth in a range of sediment types, including biogenic pelagic carbonates, lacustrine and marine clays, and possibly even in glaci-marine sediments. Thus, instead of being rarely preserved in the geological record, we find that magnetofossils are widespread. This observation has important implications for our understanding of how sediments become magnetized and highlights the need to develop a more robust basis for understanding how biogenic magnetite contributes to the magnetization of sediments. Magnetofossils also have grain sizes that are substantially smaller than the 1–15 mm size range for which there is reasonable empirical support for relative paleointensity studies. The different magnetic response of coexisting fine biogenic and coarser lithogenic particles is likely to complicate relative paleointensity studies. This issue needs much closer attention. Despite the fact that sediments have been subjected to paleomagnetic investigation for over 60 years, much remains to be understood about how they become magnetized.
    Description: Published
    Description: B08104
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: hysteresis ; magnetite ; pseudo-single domain ; single domain ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.09. Environmental magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
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    Magnetic properties of Pelagic Carbonates (2014)
    Elsevier Science Limited
    Details
    Publication Date: 2017-04-04
    Description: Pelagic carbonates are deposited far from continents, usually at water depths of 3000–6000 m, at rates below 10 cm/kyr, and are a globally important sediment type. Recent advances, with recognition of widespread preservation of biogenic magnetite (the inorganic remains of magnetotactic bacteria), have fundamentally changed our understanding of the magnetic properties of pelagic carbonates. We review evidence for the magnetic minerals typically preserved in pelagic carbonates, the effects of magnetic mineral diagenesis on paleomagnetic and environmental magnetic records of pelagic carbonates, and what magnetic properties can tell us about the open-ocean environments in which pelagic carbonates are deposited. We also discuss briefly late diagenetic remagnetisations recorded by some carbonates. Despite recent advances in our knowledge of these phenomena, much remains undiscovered. We are only at early stages of understanding how biogenic magnetite gives rise to paleomagnetic signals in sediments and whether it carries a poorly understood biogeochemical remanent magnetisation. Recently developed techniques have potential for testing how different magnetotactic bacterial species, which produce different magnetite morphologies, respond to changing nutrient and oxygenation conditions. Future work needs to test whether it is possible to develop proxies for ancient nutrient conditions from well-calibrated modern magnetotactic bacterial occurrences. A tantalizing link between giant magnetofossils and Paleogene hyperthermal events needs to be tested; much remains to be learned about the relationship between climate and the organisms that biomineralised these large and novel magnetite morphologies. Rather than being a well-worn subject that has been studied for over 60 years, the magnetic properties of pelagic carbonates hold many secrets that await discovery.
    Description: Published
    Description: 111-139
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Pelagic carbonate ; Limestone ; Magnetic minerals ; Biogenic magnetite ; Magnetofossils ; Diagenesis ; Remagnetisation ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.05. Geomagnetism::04.05.09. Environmental magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
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    Assimilated ozone from EOS-Aura: Evaluation of the tropopause region and tropospheric columns (2007)
    In:  EPIC3Journal of Geophysical Research, 113, D16S32
    Details
    Publication Date: 2019-12-03
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 9
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    Influencia de preservantes químicos sobre la vida de anaquel de carne de res molida (2013)
    Details
    Publication Date: 2021-05-19
    Description: En este trabajo se emplearon lactato de sodio, metabisulfito de sodio, acetato de sodio y sorbato de potasio para la conservación de picadillo de carne de res. Se elaboró picadillo de res que se mezcló durante 5 a 10 min con los siguientes preservantes químicos: 1000 mg/kg de sorbato de potasio (Variante 2), 2 % de lactato de sodio más 0,3 % de acetato de sodio (Variante 3) y 450 mg/kg de SO2 adicionado como metabisulfito de sodio (Variante 4) y se hizo una variante control sin preservante añadido (Variante 1). Las masas elaboradas se embutieron en tripa impermeable de 80 mm. Los picadillos se almacenaron a dos rangos de temperatura: 0 a 5 °C y 8 a 10 °C. La caracterización de los picadillos arrojó que las 4 variantes tenían similar composición físico-química y microbiológica, pero diferían en las características sensoriales. El picadillo con la mezcla lactato/acetato de sodio tuvo un sabor atípico como a “bicarbonato” que se enmascaró al ser condimentado. Todos los preservantes utilizados en el estudio aumentan sustancialmente la vida de anaquel de los picadillos de res independiente de la temperatura de conservación. El preservante que más inhibió los microorganismos fue el metabisulfito de sodio.
    Description: Sodium lactate, sodium metabisulphite and potassium sorbate were used to preserve ground beef meat. Ground beef meat was elaborated and it was mixed during 5-10 min with the following chemical preservatives: 1000 mg/kg of potassium sorbate (Var. 2), 2 % of sodium lactate more 0.3 % of sodium acetate (Var. 3) and 450 mg/kg of SO2 added as sodium metabisulphite (Var. 4). A Control was made without preservative added (Var. 1). The masses were stuffed and stored at two temperature ranges (0 - 5°C and 8 - 10°C). The characterization of ground meat showed that the four variants had similar physico-chemical and microbiological composition, but they differed in sensorial characteristics. Ground meat with the mixture sodium lactate/acetate had a flavor like “bicarbonate”, which is masked when the ground meat is seasoned. All preservatives used in the study increased the ground beef meat shelf-life, independently of the conservation temperature. The preservative that more efficiently inhibited the microorganisms was the sodium metabisulphite.
    Description: Published
    Description: mince meats
    Description: characterization
    Description: impermeable casing
    Keywords: Beef ; Wrapping ; Shelf life ; Preservatives
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed , Article
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  • 10
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    Magnetic properties of sedimentary greigite (Fe3S4): an update (2011)
    AGU
    Details
    Publication Date: 2017-04-04
    Description: Accepted for publication in Reviews of Geophysics. Copyright (2010) American Geophysical Union
    Description: Greigite (Fe3S4) is an authigenic ferrimagnetic mineral that grows as a precursor to pyrite during early diagenetic sedimentary sulfate reduction. It can also grow at any time when dissolved iron and sulfide are available during diagenesis. Greigite is important in paleomagnetic, environmental, biological, biogeochemical, tectonic, and industrial processes. Much recent progress has been made in understanding its magnetic properties. Greigite is an inverse spinel and a collinear ferrimagnet with antiferromagnetic coupling between iron in octahedral and tetrahedral sites. The crystallographic c-axis is the easy axis of magnetization, with magnetic properties dominated by magnetocrystalline anisotropy. Robust empirical estimates of the saturation magnetization, anisotropy constant, and exchange constant for greigite have been obtained recently for the first time, and the first robust estimate of the low-field magnetic susceptibility is reported here. The Curie temperature of greigite remains unknown, but must exceed 350°C. Greigite lacks a low-temperature magnetic transition. Based on preliminary micromagnetic modeling, the size range for stable single domain behavior is 17-200 nm for cubic crystals and 17-500 nm for octahedral crystals. Gradual variation in magnetic properties is observed through the pseudo-single domain size range. We systematically document the known magnetic properties of greigite (at high, ambient and low temperatures, and with alternating and direct fields) and illustrate how grain size variations affect magnetic properties. Recognition of this range of magnetic properties will aid identification and constrain interpretation of magnetic signals carried by greigite, which is increasingly proving to be environmentally important and responsible for complex paleomagnetic records, including widespread remagnetizations.
    Description: In press
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: open
    Keywords: greigite ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.09. Environmental magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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