Bingquan Li

Stresses exerted by ZnO, CeO2 and anatase TiO2 nanoparticles on the Nitrosomonas europaea.

Recent studies have shown that nano-bio interfaces are the most complex and the least understood. Notably, nanotoxicity of these nanoparticles is not even well recognized. In this work, we examined the toxic effects of different nanoparticles on bacteria cells (Nitrosomonas europaea). The four nanoparticles involved are: 25 nm anatase TiO(2), 200 nm anatase TiO(2), ZnO and CeO(2) particles. These particles will have different electrical charges in the cell cultivating media. It has been observed that even with only 4 h of dosing, all of the particles caused apparent morphological damage to the cells. Experimental results suggest that ZnO particles exert the stress on cells by its dissolution and releasing of Zn(2+) ions. The TEM and AUC (analytical ultracentrifuge) result suggest that cells become heavier in presence of CeO(2) and TiO(2) particles. No visible clear intrusions of bulk nanoparticles were observed. However, both the analytical ultracentrifuge and TEM results show that cells are heavier when being damaged.

Confinement-induced super strong PS/MWNT composite nanofibers

Shear Modulation Force Microscopy (SMFM) together with the Atomic Force Microscopy (AFM) based three-point bending technique were used to measure the mechanical properties of electrospun polymers and polymer nanocomposite fibers. Both techniques showed that the moduli of the fibers increased significantly with decreasing fiber diameter. We attributed this enhancement to the orientation of polymer chains which occurs during the electrospinning process. We then predicted, and confirmed experimentally, that the phenomenon scales with Rg rather than with the absolute fiber diameter and can propagate radially for large distances (~20Rg) into the fiber interior. The inclusion of nanotubes into the fibers further enhanced the orientation by introducing additional surfaces. The additional increase in modulus (more than an order of magnitude) could then be explained by the same model and scaled on a universal curve.

Imaging and estimating the surface heterogeneity on a droplet containing cosolvents.

Cosolvents have numerous applications in many industries as well as scientific research. The shortage in the knowledge of the structures in a cosolvent system is significant. In this work, we display the spatial as well as the kinetic distribution of the cosolvents using droplets as paradigms. When an alcohol/water-containing sessile droplet evaporates on a substrate, it phase segregates into a water-enriched core and a thin alcohol prevailing shell. This is considered to be due to the different escaping rate of solvents out of the liquid-vapor (l-v) interfaces. In between the core and shell phases, there exists a rough and solid-like liquid-liquid (l-l) wall interface as marked by the fluorescent polystyrene spheres and imaged by a confocal microscope. Holes and patches of beads are observed to form on this phase boundary. The water-dispersed beads prefer to partition within the core. The shell prevails in the droplet during most of the drying and shrinks with the l-v boundary. By monitoring the morphological progression of the droplet, the composition of the cosolvent at the liquid-vapor interface is obtained.

Hildebrand solubility parameters measurement via sessile drops evaporation

A method for the measurement of Hildebrand solubility parameter has been developed. This method was based on the measurement of the sessile drop contact angle and contact base width during its evaporation. Experimental results showed that this method is accurate and insensitive to the measurement conditions. The major advantages of this method are that it is time efficient and requires a small amount of liquid (microliter) for the measurement.

Evidence of Q 2 Q ¯ 2 Mesons in p ¯ n Annihilations and γ γ Reactions

A new resonance at 1480 MeV with a width of 110 MeV is found in p-barn annihilations in the channel p-barn..--> pi../sup -/X/sub 0/(1480)..--> pi../sup -/rho/sup 0/rho/sup 0/. Its mass, width, spin, and parity are shown to be consistent with the rho/sup 0/rho/sup 0/ enhancement observed in ..gamma gamma.. reactions. Together with the suppression in the ..gamma gamma -->..rho/sup +/rho/sup -/ data which requires the admixture of an isotensor structure, this rho/sup 0/rho/sup 0/ resonance in p-barn annihilation and ..gamma gamma.. reactions and their small ..pi pi.. branching ratios represent the best evidence yet for Q/sup 2/Q-bar/sup 2/ states. A rho/sup -/rho/sup -/ resonance in p-barn annihilations which would betray the exotic isotensor nature of the resonance is predicted.