The Existing Methods and Novel Approaches in Mycotoxins’ Detection

Mycotoxins represent a wide range of secondary, naturally occurring and practically unavoidable fungal metabolites. They contaminate various agricultural commodities like cereals, maize, peanuts, fruits, and feed at any stage in pre- or post-harvest conditions. Consumption of mycotoxin-contaminated food and feed can cause acute or chronic toxicity in human and animals. The risk that is posed to public health have prompted the need to develop methods of analysis and detection of mycotoxins in food products. Mycotoxins wide range of structural diversity, high chemical stability, and low concentrations in tested samples require robust, effective, and comprehensible detection methods. This review summarizes current methods, such as chromatographic and immunochemical techniques, as well as novel, alternative approaches like biosensors, electronic noses, or molecularly imprinted polymers that have been successfully applied in detection and identification of various mycotoxins in food commodities. In order to highlight the significance of sampling and sample treatment in the analytical process, these steps have been comprehensively described.     

Nanobuffering property of Fe3O4 magnetic nanoparticles in aqueous solution

In the present study, the buffering effect of magnetite nanoparticles (Fe₃O₄) dispersed in an aqueous solution on the local pH$pH$ value is investigated. It manifests itself in the fact that when some amount of acid or base is added to the solution then the solution near the nanoparticles surface becomes, respectively, less acidic and less alkaline than it is expected. It is the result of both the local electrostatic field, which represents the electric double layer at the surface of magnetic nanoparticles and the magnetic field around the nanoparticles. The magnetite nanoparticles exhibit very low toxicity and they are becoming increasingly important for new biomedical applications related to their effects on chemical reactions in body tissues and cells. The question arises, how strong are these effects at the nanoscale? The strength of the buffering property of magnetite nanoparticles is investigated both theoretically and experimentally by the direct measurement of the local pH$pH$ value of a magnetic nanoparticles suspension. The theoretical model is based on stochastic equations describing the ions diffusing in the neighborhood of the electric double layer of the magnetic material. The electric double layer is modeled with the help of the Poisson–Boltzmann model. It is directly shown that both the electrostatic field and the magnetic field are responsible for the observed local changes of the pH$pH$ value with respect to the bulk pH$pH$ value.     

Absolutely summing multipliers on abstract Hardy spaces

We study summing multipliers from Banach spaces of analytic functions on the unit disc of the complex plane to the complex Banach sequence lattices. The domain spaces are abstract variants of the classical Hardy spaces generated by the complex symmetric spaces. Applying interpolation methods, we prove the Hausdorff Young and Hardy-Littlewood type theorems. We show applications of these results to study summing multipliers from the Hardy-Orlicz spaces to the Orlicz sequence lattices. The obtained results extend the well-known results for the Hp spaces.     

Bent Carbon Surface Moieties as Active Sites on Carbon Catalysts for Phosgene Synthesis

Active sites in carbon‐catalyzed phosgene synthesis from gaseous CO and Cl₂ have been identified using C₆₀ fullerene as a model catalyst. The carbon atoms distorted from sp² coordination in non‐planar carbon units are concluded to generate active Cl₂. Experiments and density functional theory calculations indicate the formation of a surface‐bound [C₆₀???Cl₂] chlorine species with radical character as key intermediate during phosgene formation. It reacts rapidly with physisorbed CO in a two‐step Eley–Rideal‐type mechanism.     

Complete equilibrium paths for Mises trusses

This paper presents determination of equilibrium paths for Mises trusses with different ratio of height to span. Unsymmetrical deformation modes are considered and the structure is treated as a two DOF system. First, a few special equilibrium configurations are resolved from considerations of free body diagrams. Complete equilibrium paths are determined by solving numerically the governing non-linear equilibrium equations. The stability of possible equilibrium configurations is checked using the second partial derivative test for the total potential energy. The positive definiteness of the appropriate Hessian matrices is checked numerically using the Sylvester criterion.     

Compact multipliers on spaces of analytic functions

In the paper compact multiplier operators from Banach spaces of analytic functions on the unit disk into Banach sequence lattices are studied. If , then the characterization of compact multipliers is obtained through calculating the Hausdorff measure of noncompactness of diagonal operators between Banach sequence lattices. Furthermore, in the general case , necessary and sufficient conditions for compactness are presented. Received: 12 August 2008, Revised: 11 January 2009     

Carbon Nanotubes: An Example of Multiscale Development—A Mechanistic View from the Subnanometer to the Meter Scale

We summarize the catalytic synthesis of multiwall carbon nanotubes (MWCNTs). The current understanding of the reaction mechanism is presented, in particular the catalyst design for the CCVD process is analyzed. To complement that, kinetics and reaction engineering aspects are discussed along with the impact of the reaction and reactor operation on the product properties. All these issues are analyzed from the perspective of the industrial synthesis and implications for the application of carbon nanotubes. Carbon‐nanotube technology is a perfect example of multi‐scale development and covers challenges from the nanometer to the meter scale. Problems, methods, and solutions characteristic for different scales will be highlighted. The Co/Mn catalyst is used as reference as one of the first commercially used technologies for the scalable production of multiwall carbon nanotubes.     

Studies on thermal decomposition and oxidation of CoSb<Subscript>3</Subscript>

Thermal durability of CoSb₃ in vacuum, helium and air was investigated over the temperature range of 20–850 °C. A scanning electron microscope (SEM) and X-ray powder diffraction technique were used to investigate the microstructure and to carry out the phase analysis of the degradation products. The analysis of a non-isothermal and isothermal decomposition and oxidation of the CoSb₃ powders and polycrystalline samples were performed using simultaneous TG/DTA technique. More detailed studies were carried out on the oxidation in the temperature range 400–600 °C. It was established that the decomposition products are CoSb₂ and a volatile antimony. In case of oxidation a complex three-layered scale is formed, consisting of CoSb₂O₄, CoSb₂O₆ and Sb₂O₄ layers. Both the decomposition and the oxidation kinetics are determined by a diffusion through the growing layers of products. The electrical resistivity and Seebeck coefficient measurements have been also performed on pure and oxidized samples, which showed a large influence of the oxidation on the electrical properties.