Ordered mesoporous silica cubic particles decorated with silver nanoparticles: a highly active and recyclable heterogeneous catalyst for the reduction of 4-nitrophenol.

In this work, using a modified Stöber process, we synthesized ordered mesoporous silica cubic particles (OMS-C) and prepared a nanocatalyst (Ag-OMS-C) based on OMS-C with a high surface area via an in situ auto-reduction strategy. The as-prepared Ag-OMS-C nanocomposites demonstrated open mesopores (3.51 nm), a large specific surface area (540 m2 g-1) and a high pore volume (0.88 cm3 g-1). The catalytic reduction of 4-nitrophenol (4-NP) over the Ag-OMS-C nanocatalyst was almost complete within 150 s without stirring and the rate constant k (30 × 10-3 s-1) is much higher than those of other substrate-supported Ag nanocatalysts. Moreover, the Ag-OMS-C nanocomposites hold a stable catalytic efficiency over five reaction cycles. The results indicate that the Ag-OMS-C nanocatalyst exhibited high catalytic activity and good reusability toward the reduction of 4-NP, which might be attributed to the large specific surface area, the pore structure of the nanocatalyst, as well as the synergistic effect between OMS-C and AgNPs.

Preparation of LaFeO3 nanofibers by electrospinning for gas sensors with fast response and recovery.

LaFeO(3) nanofibers are successfully prepared by the electrospinning method. XRD patterns show that the materials belong to a cubic system. After calcination at 600 °C for 3 h, SEM photographs show that the diameters of the nanofibers are about 80-90 nm and their surfaces are smooth. The response-recovery properties of an LaFeO(3) nanofiber sensor to ethanol are better than those of an LaFeO(3) nanobelt and nanoparticle sensor. LaFeO(3) nanofibers have relatively low resistance, and they improve the weakness of LaFeO(3) nanoparticles upon application. An LaFeO(3) nanofiber sensor also has good reversibility and selectivity to ethanol and is a very good p-type semiconductor material.

Synthesis and gas-sensing characteristics of WO3 nanofibers via electrospinning.

WO(3) nanofibers were synthesized using an electrospinning method and characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The obtained WO(3) nanofibers were used as sensitive materials for the detection of NH(3). Indirect-heating sensors based on WO(3) nanofibers were prepared. When the WO(3) nanofiber-based sensors were exposed to 100 ppm NH(3) at 500°C, the response is 5.5, and the response and recovery times are 1 and 5s, respectively. These results indicate that the gas sensors based on WO(3) nanofibers express high and fast response and recovery characteristics to NH(3), and the WO(3) nanofibers are promising sensitive materials for NH(3) detecting.

Synthesis and in vitro study of pseudo-peptide thioureas containing α-aminophosphonate moiety as potential antitumor agents.

Twenty pseudo-peptide thioureas IIa-l containing α-aminophosphonate moiety were synthesized from the reaction of chiral α-amino carboxamide derivatives Ia-c with O,O'-dialkylisothiocyanato(phenyl)methylphosphonate 5. The synthesized compounds were completely characterized by elemental analysis, physical and spectral (IR, (1)H NMR, (13)C NMR) data. According to the preliminary studies on antitumor activities, compounds IIa-l could inhibit tumor cells PC3, Bcap37 and BGC823. These compounds displayed low to high activity by MTT assays. Among them, L-IIk, D-IIa and D-IIe were identified as potent inhibitors, with IC(50) values ranging from 4.7 to 11.2 µM according to in vitro assay.

Femtosecond laser direct patterning of sensing materials toward flexible integration of micronanosensors.

Reported is femtosecond laser direct patterning of sensing materials toward flexible integration of micronanosensors (FIMS), meaning the capability to fabricate multiple functional sensors of smaller size on a nonflat surface of a substrate that is not limited to silicon. As a representative example, a photosensitive SnO(2) colloidal solution (sol) was developed, from which complex micronanostructures were written via a two-photon absorption process. After thermal decomposition of organic components, the patterned SnO(2) microsensors responded to relative humidity (RH) with a variation range of 5 orders of magnitude. FIMS would open a new door for miniaturization of micronanosensors expected in intelligent microsystems.