High-Resolution Petrographic Evidence Confirming Detrital and Biogenic Magnetites as Remanence Carriers for Zongpu Carbonates in the Gamba Area, South Tibet

Paleocene carbonates from the Gamba area of South Tibet provide the largest paleomagnetic dataset for constraining the paleogeography of the India-Asia collision in the early stage. Previous studies argued that the characteristic remanences (ChRMs) obtained from this unit were remagnetized via orogenic fluids. This study carries out a high-resolution petrographic study on the Paleocene carbonates from Gamba aiming to test the nature of the ChRMs. Electron microscopic observation on magnetic extracts identified a large amount of detrital magnetite that are multi- to single domain in sizes and nanoscale biogenic magnetite. Minor framboidal iron oxides were also identified, which were previously interpreted as authigenic magnetite that substitutes pyrite. However, our scanning and transmission electron microscopic (SEM/TEM) observations, along with optical microscope and Raman spectrum investigations further suggest that these magnetic minerals are pigmentary hematite and goethite that are incapable of carrying a stable primary magnetization. We therefore argue that the ChRMs of the limestones from the Zongpu Formation in the Gamba area are carried by detrital and biogenic magnetites rather than authigenic magnetite. The paleomagnetic data from the Gamba area are interpreted as primary origin and can thus be used for tectonic reconstructions. We emphasize that magnetic extraction, integrated with advanced mineralogic studies (e.g., electron backscatter diffraction and electron diffraction) are effective approaches for investigating the origin of magnetic carriers in carbonate rocks.

Intermediate field directions recorded in Pliocene basalts in Styria (Austria): evidence for cryptochron C2r.2r-1

Pliocene volcanic rocks from south-east Austria were paleomagnetically investigated. Samples were taken from 28 sites located on eight different volcanoes. Rock magnetic investigations revealed that magnetic carriers are Ti-rich or Ti-poor titanomagnetites with mainly pseudo-single-domain characteristics. Characteristic remanent magnetization directions were obtained from alternating field as well as from thermal demagnetization. Four localities give reversed directions agreeing with the expected direction from secular variation. Another four localities of the Klöch–Königsberg volcanic complex (3) and the Neuhaus volcano (1) have reversed directions with shallow inclinations and declinations of about 240° while the locality Steinberg yields a positive inclination of about 30° and 200° declination. These aberrant directions cannot be explained by local or regional tectonic movements. All virtual geomagnetic pole positions are located on the southern hemisphere. Four virtual geomagnetic poles lie close to the geographic pole, while all others are concentrated in a narrow longitude sector offshore South America (310°–355°) with low virtual geomagnetic pole latitudes ranging from − 15° to − 70°. The hypothesis that a transitional geomagnetic field configuration was recorded during the short volcanic activity of these five localities is supported by 9 paleointensity results and 39Ar/40Ar dating. Virtual geomagnetic dipole moments range from 1.1 to 2.9·1022 Am2 for sites with low VGP latitudes below about 60° and from 3.0 to 9.3·1022 Am2 for sites with higher virtual geomagnetic pole latitudes. The new 39Ar/40Ar ages of 2.51 ± 0.27 Ma for Klöch and 2.39 ± 0.03 Ma for Steinberg allow for the correlation of the Styrian transitional directions with cryptochron C2r.2r-1 of the geomagnetic polarity time scale. Graphic abstract

Magnetic Nanomaterials as Biocatalyst Carriers for Biomass Processing: Immobilization Strategies, Reusability, and Applications

Environmental concerns, along with oil shortages, have increased industrial interest in biomass conversion to produce biofuels and other valuable chemicals. A green option in biomass processing is the use of enzymes, such as cellulases, hemicellulases, and ligninolytic (laccase and peroxidases), which have outstanding specificity toward their substrates and can be reused if immobilized onto magnetic nanocarriers. Numerous studies report the biocatalysts’ performance after covalent binding or adsorption on differently functionalized magnetic nanoparticles (MNPs). Functionalization strategies of MNPs include silica-based surfaces obtained through a sol–gel process, graphene oxide-based nanocomposites, polymer-coated surfaces, grafting polymer brushes, and others, which have been emphasized in this review of the immobilization and co-immobilization of enzymes used for biomass conversion. Careful analysis of the parameters affecting the performance of enzyme immobilization for new hybrid matrices has enabled us to achieve wider tolerance to thermal or chemical stress by these biosystems during saccharification. Additionally, it has enabled the application of immobilized laccase to remove toxic organic compounds from lignin, among other recent advances addressed here related to the use of reusable magnetic carriers for bioderived chemical manufacturing.

STUDY OF PHASE FORMATION IN FE2O3-ND2O3→NDFEO3/FE2O3 NANOCOMPOSITES AS A RESULT OF THERMAL ANNEALING

The aim of this work is systematic study of the thermal annealing effect on the preparation of nanostructured composites NdFeO3/Fe2O3 with a spinel type structure. The interest in these nano­composites is due to the enormous potential of their application as a basis for magnetic devices, catalysts, and magnetic carriers for targeted drug delivery. As a synthesis method, two­stage syn­thesis was used, which includes mechanochemical grinding of nanopowders Fe2O3 and Nd2O3 in a planetary mill, followed by thermal annealing of the resulting mixture in a wide temperature range: 600­1000°C. During the studies carried out, it was found that in the initial state the obtained nano­composites are a mixture of a solid solution of interstitial and substitutional Fe2O3 and Nd2O3. At an annealing temperature of 600°C, the onset of the formation of the NdFeO3 phase is observed, which at a temperature of 1000°C is fully formed and dominates in the composite structure (content more than 85%). It was also found that during thermal sintering, the processes of phase transformations of the Fe2O3­Nd2O3→NdFeO3/Fe2O3 type are accompanied by an increase in the particle size by a factor of 1.5­2

Mathematical Modeling Of Magnetic Scaffolds For Targeted Drug Delivery And Bone Repair

<div>Magnetic bone substitutes are multifunctional nanocomposite biomaterials designed to serve as an in situ attraction platform for magnetic carriers of growth factors. The morphological and functional properties of these biomaterials were characterized so far, but very little is known on the treatment dynamics, and the latter cannot be designed from an engineering point of view. For the first time, this work deals with the mathematical modeling of the use of magnetic scaffolds and functionalized nanoparticles to evaluate the enhancement of osteogenesis and bone repair. The non-linear magnetization of the scaffolds is considered to simulate the attraction and transport of magnetic nanoparticles. Different biomaterials and drug carriers from the literature are analyzed. The drug release via RF-heating is modeled considering the multiphysics nature of the phenomena. The physiological process of bone healing is reproduced using nine non-linear equations. The influence of the delivered growth factor on osteogenesis is assessed and quantified in silico, while compared to numerical simulations of intravenous injection of growth factor and to its release from the biomaterial. The exploitation of magnetic carriers of biomolecules with magnetic scaffolds allows to produce a more homogeneous and uniform distribution of mature bone, overcoming the limitation of traditional drug delivery techniques.</div>

Mathematical Modeling Of Magnetic Scaffolds For Targeted Drug Delivery And Bone Repair

<div>Magnetic bone substitutes are multifunctional nanocomposite biomaterials designed to serve as an in situ attraction platform for magnetic carriers of growth factors. The morphological and functional properties of these biomaterials were characterized so far, but very little is known on the treatment dynamics, and the latter cannot be designed from an engineering point of view. For the first time, this work deals with the mathematical modeling of the use of magnetic scaffolds and functionalized nanoparticles to evaluate the enhancement of osteogenesis and bone repair. The non-linear magnetization of the scaffolds is considered to simulate the attraction and transport of magnetic nanoparticles. Different biomaterials and drug carriers from the literature are analyzed. The drug release via RF-heating is modeled considering the multiphysics nature of the phenomena. The physiological process of bone healing is reproduced using nine non-linear equations. The influence of the delivered growth factor on osteogenesis is assessed and quantified in silico, while compared to numerical simulations of intravenous injection of growth factor and to its release from the biomaterial. The exploitation of magnetic carriers of biomolecules with magnetic scaffolds allows to produce a more homogeneous and uniform distribution of mature bone, overcoming the limitation of traditional drug delivery techniques.</div>

Estimating the Two Graph Dextran-Stearic Acid-Spermine Polymers Based on Iron Oxide Nanoparticles as Carrier for Gene Delivery

BackgroundNon-viral gene carriers because of their limited side effects, biocompatibility, simplicity and taking the advantages of electrostatic interactions have shown noticeable potential in gene delivery. The low transfection rate of non-viral vectors under physiological conditions is a significant issue. MethodsWe investigated the efficacy of hydrophilic and hydrophobic groups on gene carriers such as two synthesized amphiphilic polymer of dextran-stearic acid-spermine (DSASP) with verified lipid and amine conjugations that associated with Fe3O4 superparamagnetic nanoparticles to promote the target delivery and decrease the transfection time using static magnetic field.ResultsOur findings illustrate that magnetic nanoparticles are spherical with positive surface charges and superparamagnetic behaviors. The DSASP–pDNA/MNPs offered a strong pDNA condensation, protection against DNase degradation, significant cell viability in HEK 293T cells. Although conjugations of spermine play a critical role in transfection efficiency, amphiphilic polymer with more derivatives of stearic acid showed better transfection yields. ConclusionDSASP amphiphilic magnetic carriers offer new insights for gene delivery due to the amine contents and ameliorate the uptake of complexes via cell membrane based on its hydrophilic surface.

Dating North Pacific Abyssal Sediments by Geomagnetic Paleointensity: Implications of Magnetization Carriers, Plio-Pleistocene Climate Change, and Benthic Redox Conditions

Non-carbonaceous abyssal fine-grained sediments cover vast parts of the North Pacific’s deep oceanic basins and gain increasing interests as glacial carbon traps. They are, however, difficult to date at an orbital-scale temporal resolution and still rarely used for paleoceanographic reconstructions. Here, we show that sedimentary records of past geomagnetic field intensity have high potential to improve reversal-based magnetostratigraphic age models. Five sediment cores from Central North Pacific mid-latitudes (39–47°N) and abyssal water depths ranging from 3,900 to 6,100 m were cube-sampled at 23 mm resolution and analyzed by automated standard paleo- and rock magnetic methods, XRF scanning, and electron microscopy. Relative Paleointensity (RPI) records were determined by comparing natural vs. anhysteretic remanent magnetization losses during alternating field demagnetization using a slope method within optimized coercivity windows. The paleomagnetic record delivered well interpretable geomagnetic reversal sequences back to 3 Ma. This age span covers the climate-induced transition from a biogenic magnetite prevalence in the Late Pliocene and Early Pleistocene to a dust-dominated detrital magnetic mineral assemblage since the Mid-Pleistocene. Volcaniclastic materials from concurrent eruptions and gravitational or contouritic sediment re-deposition along extinct seamount flanks provide a further important source of fine- to coarse-grained magnetic carriers. Surprisingly, higher proportions of biogenic vs. detrital magnetite in the late Pliocene correlate with systematically lowered RPI values, which seems to be a consequence of magnetofossil oxidation rather than reductive depletion. Our abyssal RPI records match the astronomically tuned stack of the mostly bathyal Pacific RPI records. While a stratigraphic correlation of rock magnetic and element ratio logs with standard oxygen isotope records was sporadically possible, the RPI minima allowed to establish further stratigraphic tie points at ∼50 kyr intervals. Thus, this RPI-enhanced magnetostratigraphy appears to be a major step forward to reliably date unaltered abyssal North Pacific sediments close to orbital-scale resolution.

Improvements to the Shaw-Type Absolute Palaeointensity Method

Palaeointensity information enables us to define the strength of Earth’s magnetic field over geological time, providing a window into Earth’s deep interior. The difficulties in acquiring reliable measurements are substantial, particularly from older rocks. Two of the most significant causes of experimental failure are laboratory induced alteration of the magnetic remanence carriers and effects relating to multidomain magnetic carriers. One method that has been claimed to overcome both of these problems is the Shaw method. Here we detail and evaluate the method, comparing various selection criteria in a controlled experiment performed on a large, non-ideal dataset of mainly Precambrian rocks. Monte Carlo analyses are used to determine an optimal set of selection criteria; the end result is a new, improved experimental protocol that lends itself very well to the automated Rapid 2G magnetometer system enabling experiments to be carried out expeditiously and with greater accuracy.

Young craters of Mercury correlating with offset magnetic anomalies

&lt;p&gt;In the last months of its mission, MESSENGER was able to obtain measurements at low altitude (&lt; 120 km). This has made it possible to measure small magnetic field signals, probably of crustal origin (Johnson et al, 2015). Maps of the crust signatures at 40 km altitude were produced by Hood (2016) and Hood et al. (2018), showing that the strongest anomalies are about 9 nT in the Caloris basin. Some of the anomalies are associated with impact craters, and it has been demonstrated that this is not a coincidence (Hood et al., 2018). It is believed that these anomalies are the result of impactor materials rich in magnetic carriers (e.g., metallic iron) that were incorporated on the surface acquiring remanent magnetic fields during the cooling of the material. We analyzed whether the anomalies of the crustal field are related to geological characteristics by examining two Hermean craters in order to test this impactor hypothesis. Anomalies associated with Rustaveli and Stieglitz craters are slightly or totally asymmetric with respect to the crater center. The morphology and geological setting of these two fresh impact craters that still maintain a well-preserved ejecta blanket and visible secondary crater chains are investigated to constrain the overall impact dynamics. In both cases, slight asymmetries in the morphology and ejecta distribution show that the magnetic anomalies correlate well with the location of impact melt. Rustaveli is associated with a ~5 nT crustal magnetic anomaly centered close to the crater&amp;#8217;s midpoint, although offset ~20 km east-southeast. This offset is somewhat consistent with the downrange direction implied by Rustaveli&amp;#8217;s impact melt and crater chains distribution. For Stieglitz, an anomaly larger than 3 nT includes most of the ejecta melt locations towards southwest. The ejecta melt cluster to the north of the crater corresponds to an anomaly of ~5 nT, while the largest anomaly of ~7 nT is found further north and closely corresponds to the crater&amp;#8217;s deepest chain. For both craters, the melt likely recorded the prevailing magnetic field of Mercury after quenching. Hence, both impactors brought magnetic carriers to the surface that could record the past magnetic field of Mercury.&lt;em&gt; Acknowledgments:&lt;/em&gt; &lt;em&gt;The authors gratefully acknowledge funding from the Italian Space Agency (ASI) under ASI-INAF agreement 2017-47-H.0 and the European Union&amp;#8217;s Horizon 2020 research and innovation programme under grant agreement No. 776276.&lt;/em&gt;&lt;/p&gt; &lt;p&gt;Hood, J. Geophys. Res. Planets 121, 2016;&lt;br /&gt;Hood et al., J. Geophys. Res. Planets 123, 2018;&lt;br /&gt;Johnson et al., Science 348, 2015.&lt;/p&gt;