Huihui Yang

The shape effect of mesoporous silica nanoparticles on intracellular reactive oxygen species in A375 cells

Mesoporous silica nanoparticles (MSNs) have attracted great attention in various biomedical applications. However, a detailed mechanism of intracellular behavior, such as reactive oxygen species (ROS), induced by MSNs, has been still paid little consideration to date. In this study, we first found that MSNs with different aspect ratios (1, 2, and 4) could decrease the intracellular ROS level in serum-free media, whereas the introduction of serum proteins could upregulate and display shape-dependent behavior. The ROS regulation mechanism by particle shapes in A375 cells was then analyzed by examining the endocytosis amount of MSNs, the mitochondrial damage, and the ROS-scavenging ability. These results indicated that the particle shapes play significant roles in regulating endogenous ROS. We envisage that the complete oxidative stress study of different shaped MSNs would provide important guidelines when considering the overall toxicity of these nanocarriers in biomedical applications.

Surface reactivity of hydroxyapatite nanocoatings deposited on iron oxide magnetic spheres toward toxic metals

HYPOTHESISnHydroxyapatite and magnetite are two environmentally-friendly mineral phases that have fruitful properties for remediation process. The formation of magnetic core@sorbent shell nanostructures should provide efficient materials for toxic metal removal from aqueous media. However the nanoscale confinement of hydroxyapatite may influence its reactivity.nnnEXPERIMENTSnFe3O4@Hydroxyapatite nanocomposites were prepared by surface-controlled precipitation of hydroxyapatite layers from 10 nm to 150 nm in thickness on iron oxide spheres. The surface reactivity of the core-shell particles toward selected inorganic ions of environmental relevance (Pb(II), Y(III), Eu(III), Sb(III)) was studied by batch sorption experiments, X-ray diffraction and electron microscopy.nnnFINDINGSnThe reactivity of the hydroxyapatite coating varied from partial cation exchange to dissolution/transformation of the shell. The nature and extent of the reactions depended significantly on the hydroxyapatite layer structure but was not significantly influenced by the magnetic core. These novel nanocomposites should be useful for environmental applications.

Magnetically recoverable iron oxide–hydroxyapatite nanocomposites for lead removal

AbstractnMagnetite–hydroxyapatite nanocomposites were prepared by in situ precipitation of the calcium phosphate phase in an iron oxide colloidal suspension. Homogeneous magnetic powders were obtained with iron oxide content up to 50xa0wt%, without perturbation of the magnetite structure nor formation of additional calcium phosphates. The surface area of the composite powder was significantly increased after incorporation of magnetite due to the better apatite particle dispersion. This results in an increased available reactive surface, favoring lead sorption and hydroxypyromorphite precipitation, both leading to an enhanced lead removal capacity of the composite materials. The magnetic properties of magnetite nanocrystals were preserved upon association with hydroxyapatite. Full recovery of the composite powder after lead removal could be achieved using a simple magnet at a relatively low iron oxide content (20xa0wt%). This indicates a strong interaction between hydroxyapatite and magnetite particles within the composite powder. The procedure is simple, easily scalable and involves only environmental friendly materials.

The BESIII detector magnet

Publisher Summary BESIII (Beijing Spectrometer III) is a detector designed to run in the autumn 2007 at a 1 ╳ 10 33 cm -2 s -1 luminosity @1.89 GeV at BEPCII (Beijing Electron–Positron Collider II) at IHEP Beijing. It has a 1 T superconducting solenoid magnet with the inner winding diameter of 2962 mm, winding length of 3532 mm, and a 600 tonne flux return yoke. The indirectly cooled, pure aluminum stabilized single layer coil is internally wounded with a 4 kA superconductor. The magnet design is described. The NbTi/Cu superconductor has been delivered and the critical current test of a short sample of the superconductor has been performed. An inner winding machine is under construction.