Modulated self-reversed magnetic hysteresis in iron oxides

Hierarchical Magnetic Films for High-Performance Plasmonic Sensors

Hierarchically structured films comprise a growing section of the field of surface-enhanced Raman spectroscopy (SERS). Here, we report a novel, powerfully enhancing hierarchical plasmonic substrate featuring patterned multilayers of magnetic iron oxide nanospheres using an external magnetic field to create sets of radial ridges. This new substrate allows for effective analyte adsorption and significant Raman signal enhancement, thanks to the contribution of both the magnetic and plasmonic components to the electromagnetic hotspots. We demonstrate significant and reliable Raman enhancement for polycyclic aromatic hydrocarbons (PAHs), dilute but persistent environmental pollutants, in a complex and real-world matrix of produced water (PW). The substrate activity for PAHs is validated by gas chromatography-mass spectrometry analysis. An impressive signal-to-noise ratio (SNR) of several dB enables detection of the analyte below 1 ppm. This multilayer magnetic film sensor substrate shows remarkable stability and robustness suitable for real-world applications while boasting simple methods and strong potential to scale up fabrication.

Impact of metallic trace elements on relaxivities of iron-oxide contrast agents

In this work, well-defined 3 nm-sized Ca²⁺, Fe³⁺, Na⁺, Mg²⁺, Zn²⁺, Ni²⁺, Co²⁺, and Cd²⁺ cation-adsorbed Fe₃O₄/γ-Fe₂O₃ nanoparticles were used as prototype systems to investigate the influence of metallic trace elements in body fluids on the relaxivities of iron-oxide contrast agents. It was found that surface-adsorbed cations formed a deterioration layer to induce pronounced relaxivity loss. Theoretical study showed that such relaxivity loss can be well described by a modified GCAS function, taking into account the harmonic cation oscillations around Fe₃O₄/γ-Fe₂O₃ nanoparticles. Quantum mechanics analyses revealed that even-parity and odd-parity states of harmonic oscillations are dominant in r₁ and r₂ relaxivities, respectively. Moreover, the harmonic oscillations of Na⁺ and Mg²⁺ cations around Fe₃O₄/γ-Fe₂O₃ nanoparticles are found to be classical forbidden, which are quite different from their counterparts located in the classical permissive area.

Distribution of relaxivity loss can be well described by a modified GCAS function.

Defect mediated magnetic transitions in Fe and Mn doped MoS2

We report single-phase syntheses of undoped 2H-MoS₂ as well as Mn and Fe doped MoS₂ by a facile hydrothermal route.