Self-organized carbon connections between catalyst particles on a silicon surface exposed to atmospheric-pressure Ar + CH4 microplasmas

Ag nanoparticles and Fe-coated Si micrograins were separately deposited onto Si(1 0 0) surfaces and then exposed to an Ar + CH₄ microplasma at atmospheric pressure. For the Ag nanoparticles, self-organized carbon nanowires, up to 400 nm in length were produced, whereas for the Fe-coated Si micrograins carbon connections with the length up to 100 μm were synthesized on the plasma-exposed surface area of about 0.5 mm². The experiment has revealed that long carbon connections and short nanowires demonstrate quite similar behavior and structure. While most connections/nanowires tended to link the nearest particles, some wires were found to ‘dissolve’ into the substrate without terminating at the second particle. Both connections and nanowires are mostly linear, but long carbon connections can form kinks which were not observed in the carbon nanowire networks. A growth scenario explaining the carbon structure nucleation and growth is proposed. Multiscale numerical simulations reveal that the electric field pattern around the growing connections/nanowires strongly affects the surface diffusion of carbon adatoms, the main driving force for the observed self-organization in the system. The results suggest that the microplasma-generated surface charges can be used as effective controls for the self-organized formation of complex carbon-based nano-networks for integrated nanodevices.     

Phase diffraction gratings formed based on the phenomenon of single crystal twinning

Phase diffraction gratings can be created using the phenomenon of crystal twinning. Conditions of the grating formation and possibilities for increasing the quality of gratings are considered.     

Production of greases from industrial petroleum wastes

Petroleum-containing industrial wastes and petroleum products lost during processes (losses) are quantitatively and qualitatively basic environmental pollutants-of water, soil, and air. Some petroleum wastes from production and use of lubricants (greases, motor and industrial oils, etc.) are collected and regenerated. Wastes which are not regenerated due to their physicochemical properties are dangerous environmental pollutants. __________ Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 4, pp. 14–15, July–August, 2007.     

Free-standing alumina nanobottles and nanotubes pre-integrated into nanoporous alumina membranes

A novel interfacial structure consisting of long (up to 5 μm), thin (about 300 nm), highly-ordered, free-standing, highly-reproducible aluminum oxide nanobottles and long tubular nanocapsules attached to a rigid, thin (less than 1 μm) nanoporous anodic alumina membrane is fabricated by simple, fast, catalyst-free, environmentally friendly voltage-pulse anodization. A growth mechanism is proposed based on the formation of straight channels in alumina membrane by anodization, followed by neck formation due to a sophisticated voltage control during the process. This process can be used for the fabrication of alumina nanocontainers with highly controllable geometrical size and volume, vitally important for various applications such as material and energy storage, targeted drug and diagnostic agent delivery, controlled drug and active agent release, gene and biomolecule reservoirs, micro-biologically protected platforms, nano-bioreactors, tissue engineering and hydrogen storage.     

Controlled Growth of Single‐Walled Carbon Nanotube Networks by Catalyst Interfacial Diffusion

Single‐walled carbon nanotubes are promising for many applications due to their unique mechanical, electrical and optical properties. However, their application has been hampered so far by the lack of controllability in the direct growth process, in particular the size and chirality distributions which inevitably lead to a large variability of their electronic structures. Here we demonstrate the effect of catalyst interfacial diffusion using a tri‐layered Al₂O₃/Fe(Mo)/Al₂O₃ catalyst and achieve the effective control of density, diameter, and conductivity of the as‐grown nanotube networks. This method modulates the thickness of the top Al₂O₃ layer which affects the diffusion of Fe atoms and subsequently the formation of catalyst nanoparticles. We show that the tri‐layered catalyst allows one to vary the density of networks from 0.18 to 35 tubes/μm², the diameter from 1.36 to 1.72 nm, and the metallic fraction from 20% to 45%. It may thus represent a promising strategy for tailoring the properties of as‐grown carbon nanotube networks for their proposed applications.     

Promising Formulations of Motor Oils with Nanodispersed Additives for Internal Combustion Engines

Chemistry and Technology of Fuels and Oils - In this paper, the influence of additives to oil on the wear of the main parts of the cylinder-piston group of diesel engines has been studied. It has...