Integrating multiple functionalities into individual nanoscale complexes is of tremendous importance in biomedicine, expanding the capabilities of nanoscale structures to perform multiple parallel tasks. Here, the ability to enhance two different imaging technologies simultaneously—fluorescence optical imaging and magnetic resonance imaging—with antibody targeting and photothermal therapeutic actuation is combined all within the same nanoshell‐based complex. The nanocomplexes are constructed by coating a gold nanoshell with a silica epilayer doped with Fe3O4 and the fluorophore ICG, which results in a high T2 relaxivity (390 mM−1 s−1) and 45× fluorescence enhancement of ICG. Bioconjugate nanocomplexes target HER2+ cells and induce photothermal cell death upon near‐IR illumination.
Bad metal properties have motivated a description of the parent iron pnictides as correlated metals on the verge of Mott localization. What has been unclear is whether interactions can push these and related compounds to the Mott-insulating side of the phase diagram. Here we consider the iron oxychalcogenides La2O2Fe2O(Se,S)2, which contain an Fe square lattice with an expanded unit cell. We show theoretically that they contain enhanced correlation effects through band narrowing compared to LaOFeAs, and we provide experimental evidence that they are Mott insulators with moderate charge gaps. We also discuss the magnetic properties in terms of a Heisenberg model with frustrating J1-J2-J2' exchange interactions on a "doubled" checkerboard lattice.
The physical properties and the band structure of the layered pnictide SrMnBi 2 were investigated. This compound has a crystal structure similar to that of the superconducting Fe pnictides, and is a bad metal with large residual resistivity. Magnetic order sets in at very high temperatures, around 290 K, as shown by magnetization, resistivity, and specific heat data. Band structure calculations using density functional theory (DFT) are consistent with the thermodynamic and transport measurements, suggesting a checkerboard antiferromagnetic (cAFM) ground state and a localized picture for the magnetism. Moreover, DFT results indicate that the Mn 3d electrons are strongly correlated, and that, unlike in the known superconductors, the Sr-Bi (1) layer is metallic. One more notable feature of the DFT calculation is the multiple Dirac-cone-like dispersion close to the Fermi level.
We present evidence of type I superconductivity in YbSb2 single crystals, from DC and AC magnetization, heat capacity and resistivity measurements. The critical temperature and critical field are determined to be Tc ≈ 1.3 K and Hc ≈ 55 Oe. A small Ginzburg-Landau parameter κ = 0.05, together with typical magnetization isotherms of type I superconductors, small critical field values, a strong Differential Paramagnetic Effect (DPE) signal, and a field-induced change from second to first order phase transition, confirm the type I nature of the superconductivity in YbSb2. A possible second superconducting state is observed in the radiofrequency (RF) susceptibility measurements, with T
The formation of Breslow intermediates in the reaction of 1,2,3-triazolylidenes (mesoionic carbenes) with aldehydes is reversible. The benzoin condensation is inhibited in deuterated methanol, allowing for H/D exchange at formyl groups.
Ultrafast relaxation dynamics for photoexcited PAH cations isolated in boric acid glass have been studied using femtosecond and picosecond transient grating spectroscopy. With the exception of perylene + , the recovery kinetics for the ground doublet (D 0 ) states of these radical cations are biexponential, containing a fast (< 200 fs) and a slow (3-20 ps) components. No temperature dependence or isotope effect was observed for the fast component, whereas the slow component exhibits both the H/D isotope effect (1.1-1.3) and strong temperature dependence (15 to 300 K). We suggest that the fast component is due to internal D n to D 0 conversion and the slow component is due to vibrational energy transfer (VET) from a hot D 0 state to the glass matrix. The observed rapid, efficient deactivation of the photoexcited PAH cations accounts for their remarkable photostability and have important implications for astrochemistry, as these cations are the leading candidates for the species responsible for the diffuse interstellar bands (DIB) observed throughout the Galaxy.
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