Direct synthesis of carbon nanofibers on the surface of copper powder

A novel approach to synthesize carbon nanofibers (CNFs) directly on the surface of metal μm-sized particles to evenly disperse the carbon nanomaterials in a composite material was proposed. As a metal matrix, 5–10 μm copper particles were utilized. As a carbon source, C₂H₂, CH₄ and CO were examined. The best conditions were found to be in C₂H₂ (30 cm³/min) and H₂ (260 cm³/min) atmosphere at the temperature of 750 °C. The composites based on copper and CNFs prepared by vacuum hot pressing showed the increase in hardness from 35 to 60 kg/mm² almost retaining pure copper electrical properties.     

Nanocomposite Microcontainers with High Ultrasound Sensitivity

A water suspension of nanocomposite microcapsules with embedded ZnO nanoparticles in the capsule shell is reported. The microcapsule morphology is characterized by confocal microscopy, TEM, SEM, and AFM before and after ultrasound treatment. A remarkably high capsule sensitivity to ultrasound is evidenced, and it is observed to grow with increasing number of ZnO nanoparticle layers in the nanocomposite shell. This effect is correlated with the mechanical properties of microcapsules measured with AFM.     

Distribution of mercury in the combustion products of coal dust in boilers with liquid slag removal

The efficiency of trapping of solid particles and mercury compounds in the operation of wet centrifugal scrubbers with a closed-cycle water spray system at a thermal power plant was evaluated. Procedures were proposed for the monitoring of mercury at all of the steps of a process cycle. A balance on mercury in the combustion of coal dust in a TP-87 boiler was calculated. It was found that at least a half of mercury that entered in the firebox of boiler with coal was released as Hg⁰ vapor with flue gases into the atmosphere. It was demonstrated that the introduction of chemical oxidizing agents into scrubber spray water dramatically increased the efficiency of mercury trapping from flue gases.     

New high-pressure phase of HfTiO4 and ZrTiO4 ceramics

We studied the high-pressure effects on the crystalline structure of monoclinic HfTiO₄ and ZrTiO₄. We found that the compressibility of these ceramics is highly non-isotropic, being the b-axis the most compressible one. In addition, the a-axis is found to have a small and negative compressibility. At 2.7 GPa (10.7 GPa) we discovered the onset of a structural phase transition in HfTiO₄ (ZrTiO₄), coexisting the low- and high-pressure phases in a broad pressure range. The new high-pressure phase has a monoclinic structure which involves an increase in the Ti-O coordination and a collapse of the cell volume. The equation of state for the low-pressure phase is also determined.     

The occurrence of perchlorate during drinking water electrolysis using BDD anodes

Electrochemical studies were carried out to estimate the risks of perchlorate formation in drinking water disinfected by direct electrolysis. Boron Doped Diamond (BDD) anodes were used in laboratory and commercially available cells at 20 °C. The current density was changed between 50 and 500 A m⁻². For comparison, other anode materials such as platinum and mixed oxide were also tested. It was found that BDD anodes have a thousandfold higher perchlorate formation potential compared with the other electrode materials that were tested. In long-term discontinuous experiments all the chloride finally reacted to form perchlorate. The same result was obtained when probable oxychlorine intermediates (OCl⁻, ClO₂⁻, ClO₃⁻) were electrolysed in synthetic waters in the ppm range of concentrations. The tendency to form perchlorate was confirmed when the flow rate of drinking water was varied between 100 and 300 L h⁻¹ and the temperature increased to 30 °C. In a continuous flow mode of operation a higher chloride concentration in the water resulted in a lower perchlorate formation. This can be explained by reaction competition of species near and on the anode surface for experiments both with synthetic and local drinking waters. It is concluded that the use of electrodes producing highly reactive species must be more carefully controlled in hygienically and environmentally oriented applications.     

Kinetics and mechanism of low-temperature ozone decomposition by Co-ions adsorbed on silica

Kinetics and mechanism of low-temperature ozone ((5–50) × 10⁻³ mol/m³ in the gas–air mixture) decomposition by Co-catalysts supported on silica have been studied. Co-ions adsorbed on silica react with surface oxygen species, thus resulting in an active catalyst. Low concentrations of Co-ions form a monolayer on the surface. Their specific catalytic activity remained constant, but sharply decreased at higher concentrations due to a formation of polynuclear Co-complexes. Ozone decomposition may occur either as a stoichiometric or catalytic process, depending on the ozone and catalyst concentrations. The turnover number increases with ozone concentration reaching a saturation point. It also increases with Co-concentration in the beginning, but drops at a concentration >1 × 10⁻⁴ mol/g. The mechanism of the reaction is discussed.     

FPGA realization of the LIRA neural classifier

Different types of neural networks can be used to classify images. We propose to apply LIRA (LImited Receptive Area) neural classifier to work with images. To accelerate the neural network functioning we propose a digital implementation of the LIRA neural classifier. We begin with a neuron design, and then continue with the neural network simulation. The advantage of neural network is its parallel structure and possibility of the training. FPGA (Field Programmable Gate Array) allows the implementation of these parallel algorithms in a single device. Speed of classification is one of the most important requirements in adaptive control systems based on computer vision. The contribution of this article is LIRA neural classifier implementation with FPGA for two classes to accelerate the training and recognition processes.     

Sorption properties of polymers based on N‐substituted maleimides

Physicochemical and functional properties of 2,2‐diallyl‐1,1,3,3‐tetraethylguanidinium chloride copolymers with N‐(n‐carboxyphenyl)maleimide, of N‐vinylpyrrolidone with N‐(n‐carboxyphenyl)maleimide, and of N‐vinylpyrrolidone with N‐phenylmaleimide have been investigated. Specific surface area and porosity of the copolymers under investigation have been determined by using the low‐temperature adsorption method. Electron microscope investigations in surfaces of the polymers have evinced that all of them have a spongy microstructure, the N‐vinylpyrrolidone copolymer with N‐(n‐carboxyphenyl)maleimide being the most homogeneous of these. Sorption capacity of the copolymers toward Re(VII) ions has been investigated. The process is described by the Langmuir isotherm. The pH is the most important parameter for sorption process of Re(VII). In the conjoint presence of Re(VII) and Mo(VI) in a solution of acid and ammoniac mediums, rhenium can be separated from molybdenum by using the sorbents under investigation at pH > 4.5 or at hydrochloric acid concentrations 0.1 mol L^?1 and more. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013