Oxidation of 17alpha-ethinylestradiol with Mn(III) and product identification

With increasing concern about the contamination of aquatic environments by estrogenic pollutants, removal of synthetic estrogens such as 17alpha-ethinylestradiol (EE2) has been widely studied, especially with respect to the treatment methods. However, the degradation products have rarely been identified. The purpose of this study was to identify structurally the oxidation products of EE2. Mn(III) was used as an oxidizing agent. To obtain sufficient oxidation products for HPLC, LC-MS and NMR spectroscopy, a highly concentrated solution of EE2 (1mM) was prepared in a mixture of water and a water-miscible organic solvent. From HPLC of the reaction products, a single compound (I) was found to be predominant. From LC-MS, its molecular mass was found to be 294, and two hydrogens were believed to have been removed from EE2 (M.W. 296) to form a C=C . The structure of compound I (position of the double bond) was determined using 1H NMR, 13C NMR, H-H COSY, HSQC and HMBC. As minor products, isomeric dimers (M.W. 590) of EE2, as well as the products (M.W. 588) in which EE2 was coupled to compound I were also formed during the Mn(III)-mediated oxidation of EE2.     

Memory characteristics of a self-assembled monolayer of Pt nanoparticles as a charge trapping layer

A self-assembled monolayer of Pt nanoparticles (NPs) was studied as a charge trapping layer for non-volatile memory (NVM) applications. Pt NPs with a narrow size distribution (diameter ～4?nm) were synthesized via an alcohol reduction method. The monolayer of these Pt NPs was immobilized on a SiO(2) substrate using poly(4-vinylpyridine) (P4VP) as a surface modifier. A metal-oxide-semiconductor (MOS) type memory device with Pt NPs exhibits a relatively large memory window of 5.8?V under ± 7?V for program/erase voltage. These results indicate that the self-assembled Pt NPs can be utilized for NVM devices.     

Mechanical properties of functionalized carbon nanotubes

Carbon nanotubes (CNTs) used to reinforce polymer matrix composites are functionalized to form covalent bonds with the polymer in order to enhance the CNT/polymer interfaces. These bonds destroy the perfect atomic structures of a CNT and degrade its mechanical properties. We use atomistic simulations to study the effect of hydrogenization on the mechanical properties of single-wall carbon nanotubes. The elastic modulus of CNTs gradually decreases with the increasing functionalization (percentage of C-H bonds). However, both the strength and ductility drop sharply at a small percentage of functionalization, reflecting their sensitivity to C-H bonds. The cluster C-H bonds forming two rings leads to a significant reduction in the strength and ductility. The effect of carbonization has essentially the same effect as hydrogenization.     

Novel fabrication of an SnO(2) nanowire gas sensor with high sensitivity

We fabricated a nanowire-based gas sensor using a simple method of growing SnO(2) nanowires bridging the gap between two pre-patterned Au catalysts, in which the electrical contacts to the nanowires are self-assembled during the synthesis of the nanowires. The gas sensing capability of this network-structured gas sensor was demonstrated using a diluted NO(2). The sensitivity, as a function of temperature, was highest at 200?°C and was determined to be 18 and 180 when the NO(2) concentration was 0.5 and 5?ppm, respectively. Our sensor showed higher sensitivity compared to different types of sensors including SnO(2) powder-based thin films, SnO(2) coating on carbon nanotubes or single/multiple SnO(2) nanobelts. The enhanced sensitivity was attributed to the additional modulation of the sensor resistance due to the potential barrier at nanowire/nanowire junctions as well as the surface depletion region of each nanowire.     

Atomistic study of structures and elastic properties of single crystalline ZnO nanotubes

The structural stability and Young's modulus of single crystalline ZnO nanotubes are investigated using atomistic simulations. Unlike the case for conventional layered nanotubes, the energetic stability of single crystalline ZnO nanotubes is related to the wall thickness. The potential energy of ZnO nanotubes with fixed outer and inner diameters decreases with increasing wall thickness, while the nanotubes with the same wall thickness are independent of the outer and inner diameters. The transformation of single crystalline ZnO nanotubes with a double layer from wurtzite phase to graphitic phase suggests the possibility of wall-typed ZnO nanotubes. The size-dependent Young's modulus of ZnO nanotubes is also investigated. The wall thickness plays a significant role in the Young's modulus of single crystalline ZnO nanotubes, whereas the variation of outer and inner diameters slightly affects the Young's modulus of nanotubes with same wall thickness.     

Effects of bioactive ceramics on the pathogenesis of rat vascular smooth muscle cells treated with phorbol 12-myristate 13-acetate

Vascular smooth muscle cells (VSMCs) play a pivotal role in vascular injury through proliferation and migration. Pro-inflammatory cytokines and cyclooxygenase (COX)-2 and nitric oxide synthase (NOS) are highly associated with the pathogenesis of VSMCs. We investigated the effect of bioactive ceramics on the expression of inflammatory cytokines, COX-2, and inducible NOS (iNOS) induced by phorbol 12-myristate 13-acetate (PMA) in rat VSMCs. The ceramics inhibited mRNA expression of IL-1β, TNF-α, IL-6, COX-2, and iNOS. Prostaglandin release was also diminished by the ceramics. The bioactive ceramics effect on cytokines, COX-2, and iNOS expression was achieved by inhibition of NF-κB activity. Interestingly, the ceramics-induced up-regulation of expression of endothelial NOS resulted in an increase of nitric oxide production. Thus, bioactive ceramics may have dual effects on the pathogenesis of VSMCs by regulation of NF-κB activity and NO production.