An official website of the United States government
Geomagnetic methods allow us to explore the behavior of Earth's geodynamo, constrain Earth's composition and structure, and locate critical minerals and other resources essential for modern technologies and the energy transition. The magnetic properties of rocks and sediments are assumed to be stable and largely attributable to inorganic processes. This conventional view overlooks mounting evidence of microorganisms as key players in rock transformations and geological processes. Iron-bearing minerals are ubiquitous in most environments and are commonly used by microorganisms as electron donors and acceptors. Microorganisms modulate rock magnetic properties by creating, altering, and dissolving Fe-bearing minerals, potentially modifying the original magnetization, complicating interpretations of the magnetic record. This review provides an overview of biogenic pathways that modulate magnetic minerals and discusses common, yet underutilized, magnetic methods for capturing such behavior. Appreciating the influence of microbial activities on magnetic properties will improve our interpretations of Earth's geologic past and its elemental cycling.▪Microorganisms modulate rock magnetic properties, challenging traditional views of a geologically stable magnetic record formed solely by inorganic processes.▪Microbial iron cycling modulates magnetic properties modifying magnetic information recorded in rocks.▪Microbial processes may have impacted Earth's magnetic history more deeply than previously understood.▪Recognizing microbial contributions is critical for accurate interpretation of paleomagnetic and environmental magnetic records and could aid in the search for life on other planetary bodies.
more »
« less
This content will become publicly available on January 1, 2027
Size effects in magnetic separation for rapid and efficient bacteria removal
Porous magnetic nanoparticles show pronounced size-dependent effects on bacterial removal, providing guidance for designing effective magnetic adsorbents.
more »
« less
- Award ID(s):
- 2135687
- PAR ID:
- 10659211
- Publisher / Repository:
- The Royal Society of Chemistry
- Date Published:
- Journal Name:
- Nanoscale
- ISSN:
- 2040-3364
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Additive manufacturing of materials using magnetic particles as feedstock has attracted tremendous attention during the past decade owing to its ability to tune both shape and magnetocrystalline anisotropy, which can significantly enhance the magnetic characteristics of materials. We demonstrate that the magnetic response of multilayered thin films of Gd5Si4 can be tailored by controlling the external magnetic field during inkjet printing. The external magnetic field aligns the magnetic particles along their magnetic easy axis, enhancing the magnetic anisotropy of the printed films. Our work demonstrates the ability to print thin magnetic films with a defined anisotropy in any chosen direction with the potential to approaching magnetic properties of corresponding single crystalline materials.more » « less
-
Abstract The dynamics of the cellular actomyosin cytoskeleton are crucial to many aspects of cellular function. Here, we describe techniques that employ active micropost array detectors (AMPADs) to measure cytoskeletal rheology and mechanical force fluctuations. The AMPADS are arrays of flexible poly(dimethylsiloxane) (PDMS) microposts with magnetic nanowires embedded in a subset of microposts to enable actuation of those posts via an externally applied magnetic field. Techniques are described to track the magnetic microposts’ motion with nanometer precision at up to 100 video frames per second to measure the local cellular rheology at well‐defined positions. Application of these high‐precision tracking techniques to the full array of microposts in contact with a cell also enables mapping of the cytoskeletal mechanical fluctuation dynamics with high spatial and temporal resolution. This article describes (1) the fabrication of magnetic micropost arrays, (2) measurement protocols for both local rheology and cytoskeletal force fluctuation mapping, and (3) special‐purpose software routines to reduce and analyze these data. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Fabrication of magnetic micropost arrays Basic Protocol 2: Data acquisition for cellular force fluctuations on non‐magnetic micropost arrays Basic Protocol 3: Data acquisition for local cellular rheology measurements with magnetic microposts Basic Protocol 4: Data reduction: determining microposts’ motion Basic Protocol 5: Data analysis: determining local rheology from magnetic microposts Basic Protocol 6: Data analysis for force fluctuation measurements Support Protocol 1: Fabrication of magnetic Ni nanowires by electrodeposition Support Protocol 2: Configuring Streampix for magnetic rheology measurementsmore » « less
-
Abstract Magnetic nanoparticles have continued to gain significant attention due to their unique magnetic properties and potential applications. However, it is still challenging to directly synthesize water-dispersible magnetic nanoparticles with controlled size for biomedical applications. This study investigates the influence of solvents on the continuous growth of magnetic nanoparticles, aiming to achieve controlled size and excellent water dispersibility via thermal decomposition in polyol solvents. The size of the nanoparticles gradually increases with longer polyol chain solvents. The increase in nanoparticles size is more significant under a higher reaction temperature (220 °C) compared to a lower temperature (190 °C). These monodispersed nanoparticles exhibit strong superparamagnetic properties, improving with longer solvent chain lengths at the same size. Magnetic resonance imaging (MRI) studies reveal higher relaxivities for magnetic nanoparticles synthesized in longer-chain polyols. This research offers valuable insights for synthesizing magnetic nanoparticles with precise sizes, magnetic properties, and biomedical applications. Graphical abstractmore » « less
