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  • Author or Editor: Z. Kónya x
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The adsorption kinetics of strontium ion was studied on seven natural clay samples with radioactive tracer method. The kinetic curves were determined and the kinetic data were evaluated by forms of first-rate kinetic equations with different terms, generally used for adsorption of ions of low concentration. The adsorption process was reduced to two steps. Film diffusion and participle diffusion were found in the case of five samples. Gel diffusion, film diffusion and participle diffusion were found in the case of the other two samples. The presence of significant amount of cristobalite can explain the gel phase in these two samples. The rate coefficients of steps were calculated from the kinetic curves.

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The rheological properties of seven winter wheat cultivars from two harvest years were studied. Rheological testing included two empirical rheological methods, alveograph and extensograph. Principal component analysis on the studied rheological parameters showed that the alveograph and extensograph parameters are influenced by entirely different factors. The first component was responsible solely for the extensograph parameters, primarily for the resistance properties of dough samples. The second component affected the extensograph extensibility (E) and alveograph tenacity (P) parameters as well, in spite of the fact that these parameters refer to different properties of dough. The third component explained only alveograph parameters, such as P, L and G values. The Pearson’s correlation coefficients showed that the extensograph area parameter primarily depends on the maximum resistance to extension of dough (r=0.91). The extensibility and resistance at a constant extension of 5 cm properties did not show such strong relationship with the area parameter (r=0.56 and 0.65, respectively). The relationship between the extensograph maximum resistance and extensibility parameters was positive (r=0.20), while the correlation coefficient between alveograph P and L value was negative (r=0.34).

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By using instrumental neutron activation analysis (INAA) it has been shown that some pristine carbon SWNT's and MWNT's of different makes, contain a multitude of trace element impurities at various concentration levels including also amounts which can be considered as nanoelectronically dopant quantities. The same holds for the above mentioned carbon nanotubes also after their inadequately so-called purification.

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Male Wistar rats wearing chronically implanted cortical electrodes were exposed to Mn-containing nanoparticles via the airways for 8 weeks following a 2-week pre-exposure period. The rats’ cortical electrical activity and open field motility was recorded simultaneously, in weekly repetitions. It was supposed that this technique can provide better insight in the development of Mn-induced CNS damage. Decreased motility (less distance covered, longer periods of immobility) and increased total power of cortical electrical activity developed in parallel in the first 4–5 weeks of treatment but showed little change afterwards. Both the behavioral and the electrophysiological effect were in fair correlation with the rats’ internal Mn exposure determined from brain samples. The results confirmed the non-linear dose- and time-dependence of Mn effects suggested by previous studies. Repeated simultaneous behavioral and electrophysiological recording during a longer treatment with neurotoxic metals (or other xenobiotics) seems to be a promising method.

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Authors: D. Carta, S. Bullita, A. Falqui, M. Casula, A. Corrias and Z. Kónya

A series of Fe/Co based nanocomposites where the matrix is mesoporous ordered cubic Im3m silica (SBA-16 type) characterized by a three dimensional cage-like structure of pores were obtained by two different approaches: impregnation and gelation. X-ray diffraction and transmission electron microscopy analysis show that after metal loading, calcination at 500 °C and reduction in H2 fl ux at 800 °C the nanocomposites retain the well-ordered structure of the matrix with cubic symmetry of pores. All nanocomposites prepared were tested for the production of carbon nanotubes by catalytic chemical vapour deposition. Transmission electron microscopy points out that good quality multi-walled carbon nanotubes are obtained.

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Authors: A. Szabo, A. Fonseca, L. P. Biro, Z. Konya, I. Kiricsi, A. Volodin, C. Van Hasendonck and J. B.Nagy

Some recent results on the synthesis of coiled carbon nanotubes (CNTs) are summarized. Several supported catalysts can lead to the formation of coiled CNTs. Interestingly, certain domains of the coil pitch and coil diameter are favoured, and two “stability islands”are found in the 3D representation of the number of coiled CNTs as a function of both coil pitch and coil diameter. It is emphasized that these nanotubes are formed either by introducing pairs of five-membered ring - seven-membered ring or by forming haeckelite structures. The coiled CNTs could be used in nanocomposite reinforcement as well as special sensors based on their remarkable mechanical and electrical properties.

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