Clay-fulleropyrrolidine nanocomposites

In this work, we describe the insertion of a water-soluble bisadduct fulleropyrrolidine derivative into the interlayer space of three layered smectite clays. The composites were characterized by a combination of powder X-ray diffraction, transmission electron microscopy, X-ray photoemission and FTIR spectroscopies, and laser flash photolysis measurements. The experiments, complemented by computer simulations, give insight into the formation process, structural details, and properties of the fullerene/clay nanocomposites. The reported composite materials constitute a new hybrid system, where C-60 differs from its crystals or its solutions, and open new perspectives for the design and construction of novel C-60-based organic/clay hybrid materials.</p

Carbon Nanotubes Encapsulating Superconducting Single-Crystalline Tin Nanowires

Superconducting low dimensional systems are the natural choice for fast and sensitive infrared detection, because of their quantum nature and the low-noise, cryogenic operation environment. On the other hand, monochromatic and coherent electron beams, emitted from superconductors and carbon-based nanostructured materials, respectively, are significant for the development of electron optical systems such as electron microscopes and electron-beam nanofabrication systems. Here we describe for the first time a simple method which yields carbon nanotubes encapsulating single crystalline superconducting tin nanowires by employing the catalytic chemical vapor deposition method over solid tin dioxide. The superconducting tin nanowires, with diameters 15-35 nm, are covered with well-graphitized carbon walls and show, due to their reduced diameters, a critical magnetic field (Hc) more than 30 times higher than the value of bulk metallic tin.

NOVEL METHODS FOR AXIAL FAN IMPELLER GEOMETRY ANALYSIS AND EXPERIMENTAL INVESTIGATIONS OF THE GENERATED SWIRL TURBULENT FLOW

Geometry analysis of the axial fan impeller, experimentally obtained operating characteristics and experimental investigations of the turbulent swirl flow generated behind the impeller are presented in this paper. Formerly designed and manufactured, axial fan impeller blade geometry (originally designed by Prof. Dr-Ing. Z. Protić†) has been digitized using a three-dimensional (3D) scanner. In parallel, the same impeller has been modeled by beta version software for modeling axial turbomachines, based on modified classical calculation. These results were compared. Then, the axial fan operating characteristics were measured on the standardized test rig in the Laboratory for Hydraulic Machinery and Energy Systems, Faculty of Mechanical Engineering, University of Belgrade. Optimum blade impeller position was determined on the basis of these results. Afterwards, the impeller with optimum angle, without outlet vanes, was positioned in a circular pipe. Rotational speed has been varied in the range from 500 till 2500rpm. Reynolds numbers generated in this way, calculated for axial velocity component, were in the range from 0,8·105 till 6·105. LDA (Laser Doppler Anemometry) measurements and stereo PIV (Particle Image Velocimetry) measurements of the 3D velocity field in the swirl turbulent fluid flow behind the axial fan have been performed for each regime. Obtained results point out extraordinary complexity of the structure of generated 3D turbulent velocity fields

Synthesis and characterization of low dimensional ZnS- and PbS-semiconductor particles on a montmorillonite template

Low dimensional metal sulfide particles have been prepared in the interlayers of montmorillonites via reactions of the metal ion-exchanged clay minerals in aqueous dispersions with gaseous hydrogen sulfide. The montmorillonites separated from the Wyoming (USA) and Jelšový Potok (Slovakia) bentonites were saturated with Pb2+ or Zn2+. In the final nanohybrids, the smectite mineral can be incorporated with metal sulfide pillars and/or nanoparticles. Properties of the prepared materials were investigated by various analytical techniques. The formation of metal sulfide nanoparticles in the interlayer galleries was indicated by X-ray diffraction and energy dispersive X-ray analysis. About 50% of Pb2+ or Zn2+ present in montmorillonite has formed metal sulfide semiconducting units. Infrared spectroscopy and thermogravimetric analysis were used for characterization of starting materials and products. Ultraviolet-visible absorption and photoluminescence spectroscopies confirmed that final composite systems acquired the optical properties of the incorporated quantum low dimensional systems exhibiting blue shift of the energy gap and higher oscillator strength excitonic peaks. Larger amounts of metal sulfide nanoparticles were formed in montmorillonite Jelšový Potok probably as a consequence of its higher cation exchange capacity. © the Owner Societies

Clay-fulleropyrrolidine nanocomposites

In this work, we describe the insertion of a water-soluble bisadduct fulleropyrrolidine derivative into the interlayer space of three layered smectite clays. The composites were characterized by a combination of powder X-ray diffraction, transmission electron microscopy, X-ray photoemission and FTIR spectroscopies, and laser flash photolysis measurements. The experiments, complemented by computer simulations, give insight into the formation process, structural details, and properties of the fullerene/clay nanocomposites. The reported composite materials constitute a new hybrid system, where C-60 differs from its crystals or its solutions, and open new perspectives for the design and construction of novel C-60-based organic/clay hybrid materials