Search Results

You are looking at 1 - 5 of 5 items for :

  • Author or Editor: Z.Z. Nagy x
  • Materials and Applied Sciences x
  • All content x
Clear All Modify Search

The potentiometric electronic tongue is a new and rapidly developing technique. However, the description of the exact working mechanism is still absent. An important part of this description is the effect of the sample temperature on the measurement results. The paper reported here gives a description of the effect of temperature on results obtained with an α-Astree potentiometric electronic tongue. The yielded model was used to perform a temperature correction as if the samples were measured at room temperature (25 °c).

Restricted access
Nanopages
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.

Restricted access
Nanopages
Authors: J. B.Nagy, J. N. Coleman, A. Fonseca, A. Destrée, Z. Mekhalif, N. Moreau, L. Vast, and J. Delhalle

Organic polymers - carbon nanotubes nanocomposites are synthesized either by mechanical mixing of the two components or by covalently linking the nanotubes to the matrix. The various procedures will be overviewed and the determining factors will be identified for the best mechanical properties of the composites. On the other hand, it will be shown that for highest electrical conductivity much smaller amounts of carbon nanotubes are needed if the nanotubes can be aligned. The thermal conductivity of the nanocomposites will also be overviewed. Finally, together with nanoclay particles, nanotubes are inducing remarkable flame retardant properties in the nanocomposites materials.

Restricted access
Acta Alimentaria
Authors: R. Tömösközi-Farkas, Zs. Polgár, M. Nagy-Gasztonyi, V. Horváth, T. Renkecz, K. Simon, F. Boross, Z. Fabulya, and H. Daood

Anti-nutritive components in multi resistant potato cultivars were investigated in relation to conventional and organic farming for three years. Glycoalkaloids, nitrate, nitrite, asparagine, and glutamine contents of tubers were examined. Farming technology was found not to have an effect on the level of glycoalkaloids, which was influenced mostly by the genotype and season. Nitrogen fertilisation caused significant increase in nitrate, asparagine, and glutamine contents as compared to organic farming. Nitrite content was found to be more independent of farming technologies than nitrate. Tubers of cultivar Rioja had the lowest nitrate content irrespective of season or technology. In conclusion, the absolute amount and changes of different anti-nutritive components of potato tubers were influenced differently by the technology, genotype, and season in a complex manner. Organic farming had no effect on the glycoalkaloid content, but the nitrate levels had a tendency to be lower compared to conventional farming. This can be seen as a positive effect of organic farming.

Restricted access
Acta Alimentaria
Authors: E. Horvath-Szanics, J. Perjéssy, A. Klupács, K. Takács, A. Nagy, E. Koppány-Szabó, F. Hegyi, E. Németh-Szerdahelyi, M.Y. Du, Z.R. Wang, J.Q. Kan, and Zs. Zalán

The increasing consumer demand for less processed and more natural food products – while improving those products’ quality, safety, and shelf-life – has raised the necessity of chemical preservative replacement. Biopreservation refers to extended storage life and enhanced safety of foods using the natural microflora and (or) their antibacterial products. Chitinolytic enzymes are of biotechnological interest, since their substrate, chitin, is a major structural component of the cell wall of fungi, which are the main cause of the spoilage of food and raw plant material. Among the several organisms, many bacteria produce chitinolytic enzymes, however, this behaviour is not general. The chitinase activity of the lactic acid bacteria is scarcely known and studied.

The aim of the present study was to select Lactobacillus strains that have genes encoding chitinase, furthermore, to detect expressed enzymes and to characterise their chitinase activity. Taking into consideration the importance of chitin-bindig proteins (CBPs) in the chitinase activity, CBPs were also examined. Five Lactobacillus strains out of 43 strains from 12 different species were selected by their chitinase coding gene. The presence of the chitinase and chitin-biding protein production were confirmed, however, no chitinolytic activity has been identified.

Open access