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Magnetotactic bacteria produce magnetite nanoparticles called magnetosomes at ambient conditions via a protein‐stabilized transient amorphous precursor to obtain precise control over particle size and morphology. In a bioinspired approach, such biomineralization processes are emulated, mimicking proteins involved in magnetosome formation using the positively charged analog poly‐L‐arginine. While the additive is expensive, it remains elusive whether the change in magnetite formation mechanism arises solely from the polymer's cationic nature. This study uses different mass‐produced and sustainably sourced polycations to induce the biomineralization‐reminiscent formation of magnetite nanoparticles. These findings present how to achieve control over nanoparticle size (from 10 to 159 nm) and morphology (compact and sub‐structured) as well as magnetic properties (superparamagnetic, stable‐single‐domain, vortex state) at ambient temperature and pressure using these additives. Furthermore, the formation of large nanoparticles with the addition of poly(diallyldimethylammonium chloride) (PDADMAC) at low alkalinity highlights how magnetotactic bacteria may produce magnetite nanoparticles under similar conditions. Confirming the polycations' ability to electrostatic stabilize amorphous ferrihydrite, it is anticipated that parametric in vitro studies on polymer properties will provide valuable insights into magnetite biomineralization and aid in rationally designing magnetic nanomaterials. [ABSTRACT FROM AUTHOR]

Sumbawa's Kuris River is one of the rivers contaminated by the island's traditional gold mine. In order to detect contaminant levels, we examine the magnetic susceptibility, HCN levels, and the heavy metal contents on the river's surface sediment. Environmental pollution has been widely assessed using a combination of magnetic properties and geochemical analysis. The goals of this research are to discover how magnetic susceptibility (X) can be used as a first-order proxy for pollution. The relation between susceptibility and HCN is of particular interest, as this is a major contaminant associated with gold mining. The surface sediment samples were collected at ten different locations along the rivers. The magnetic susceptibility was determined using the Bartington MS2B, and the hydrogen cyanide (HCN) concentration was determined using Argentometric titration. The element content was determined by an Atomic Absorption Spectrometer (AAS). The low-frequency magnetic susceptibility (X1f) ranges from 71 to 115×10-8 m³/kg, with an average of 97×10-8 m³/kg, and the Xfd(%) analysis ranges from 2% to 4%. The presence of spherical iron oxides, which are indicative of combustion byproducts, was also confirmed by SEM. The samples have low magnetic susceptibility but high levels of Hg and HCN. AAS results showed high Fe, Zn, and Cu concentrations in river sediments, with more variable concentrations of Hg, Mn, As, Cr, and Au. Because Fe, Cu, As, Hg, and HCN have a significant Pearson's correlation with Xfd(%), this parameter can be a useful indicator for contamination caused by gold mining waste. [ABSTRACT FROM AUTHOR]

Demantoid from Kerman Province in south-east Iran was investigated using microscopy, spectroscopy (optical absorption, FTIR and Raman), chemical analysis (EDXRF and LA-ICP-TOF-MS) and magnetic susceptibility measurements. The samples were transparent to semi-transparent and commonly contained acicular chrysotile inclusions. Their spectroscopic and chemical properties were consistent with demantoid from serpentinite host rock. The samples ranged from yellowish green to deep green, depending on Cr and Fe content. These two elements are also largely responsible for the material's paramagnetic susceptibility. Our samples contained relatively high concentrations of the trace elements Cr, Ge, Ni and Co. Comparison with available chemical data on serpentinite-hosted demantoid from the literature suggests that Iranian demantoid can be separated from stones of other localities. [ABSTRACT FROM AUTHOR]