SFPQ, (a.k.a. PSF), is a human tumor suppressor protein that regulates many important functions in the cell nucleus including coordination of long non-coding RNA molecules into nuclear bodies. Here we describe the first crystal structures of Splicing Factor Proline and Glutamine Rich (SFPQ), revealing structural similarity to the related PSPC1/NONO heterodimer and a strikingly extended structure (over 265 Å long) formed by an unusual anti-parallel coiled-coil that results in an infinite linear polymer of SFPQ dimers within the crystals. Small-angle X-ray scattering and transmission electron microscopy experiments show that polymerization is reversible in solution and can be templated by DNA. We demonstrate that the ability to polymerize is essential for the cellular functions of SFPQ: disruptive mutation of the coiled-coil interaction motif results in SFPQ mislocalization, reduced formation of nuclear bodies, abrogated molecular interactions and deficient transcriptional regulation. The coiled-coil interaction motif thus provides a molecular explanation for the functional aggregation of SFPQ that directs its role in regulating many aspects of cellular nucleic acid metabolism.

No abstract

Lasing action is realized in a ZnO/GaN heterojunction by employing a MgO interlayer. The MgO layer can confine electrons in the ZnO layer, while holes can pass through the MgO layer and enter into the n‐ZnO layer from the p‐GaN layer. The threshold of the lasing action is as low as 0.8 mA..

No abstract

A ZnO p-n junction light-emitting diode (LED) was fabricated on a-plane Al2O3 substrate by plasma-assisted molecular-beam epitaxy. NO plasma activated by a radio frequency atomic source was used to grow the p-type ZnO layer of the LED. The current-voltage measurements at low temperatures showed a typical diode characteristic with a threshold voltage of about 4.0V under forward bias. With increasing temperature, the rectification characteristic was degraded gradually, and faded away at room temperature. Electroluminescence band of the ZnO p-n junction LED was located at the blue-violet region and was weakened significantly with increase of temperature. This thermal quenching of the electroluminescence was attributed to the degradation of the diode characteristic with temperature.

Pure polypyrrole (PPy) nanoparticles that are well-applicable for nanocomposite and nanocarbon precursor were productively synthesized by necessarily unstirred oxidative polymerization of pyrrole in acidic aqueous media at 0°C without any template. The species and concentration of acid and oxidant have been carefully investigated to optimize the polymerization yield, conjugated structure, size, and conductivity of the PPy particles. Laser particle-size analysis, field-emission scanning electron microscopy, transmission electron microscopy, and atomic force microscopy all revealed that the PPy particles produced in still acid media have narrow size distribution and uniform spheroid morphology. Homogeneous nucleation and static repulsion are proposed as the formation and self-stabilization mechanisms of the PPy nanoparticles. Combination of HNO 3 medium and (NH 4 ) 2 S 2 O 8 oxidant is optimal for the synthesis of PPy nanoparticles possessing maximal yield of 87.2%, small diameter, and high conductivity which has been confirmed by a strong UV-vis band due to a large π-conjugated chain structure. This quiescent polymerization could be simply scaled up or down to synthesize a larger or smaller amount of PPy nanoparticles without compromising their yield, structure, and properties. Furthermore, the conductivity of the nano-PPy could reach 2.8 S/cm upon doping in 2.0 M HClO 4 . Simultaneous thermogravimetry-differential thermal analysis technique demonstrates that the PPy nanoparticles at 1000°C can be efficiently carbonized into carbon nanoparticles with narrower size distribution, smaller diameter of 62 nm, and much higher conductivity of about 21 S/cm. In particular, the conductivity will dramatically be enhanced to 219 S/cm and even 370 S/cm at the carbonization and graphitization temperatures of 1300 and 2300°C in nitrogen and argon, respectively. A conductive nano-PPy/cellulose diacetate nanocomposite film with low percolation threshold down to 0.2 wt %, good conductivity stability for at least 8 weeks, and potential bioapplicability was simply fabricated. The present synthesis requires no external templates and provides a facile and direct route to scalable synthesis of PPy exclusive nanoparticles with high yield, controllable size, strong re-dispersibility, high purity, adjustable conductivity, and high nanocarbon yield.

Harding (2007) Dynamic light scattering as a relative tool for assessing the molecular integrity and stability of monoclonal antibodies, Biotechnology and Genetic Engineering Reviews, 24:1, 117-128,

ZnO nanostructures, including nanotowers, nanovolcanoes, nanorods, nanotubes, and nanoflowers, have been grown by using the hydrothermal technique. Most of the ZnO nanostructures show the perfect hexagonal cross section and well-faceted top and side surfaces. The basic chemistry and growth mechanism are discussed. By increasing the reaction time, the volcano-like and tube-like ZnO structures were formed due to the Ostwald ripening process and the selective adsorption of the complexes. By using the seed layer, the dense-arrayed, regular oriented ZnO nanorods were obtained due to the decreased nucleation barrier and the abundant interfaces as well as the increasing surface roughness.