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  • Author or Editor: A. Kiss x
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Abstract  

The aim of the present work was to provide arguments to the almost ‘hystorical’ problem of what β-tungsten is. WO3was reduced in dry H2gas atmosphere in order to examine, whether β-tungsten formed in such a way contains oxygen as part of the lattice described as WxO (e.g. W20O) or is a pure metallic phase of tungsten. As a result of thermoanalytical measurements and of chemical analysis for oxygen, the assumption is supported that in the 600-800C temperature range of metal formation not the WxO (β-W)→W(α-W) transformation but the β-W→α-W structural rearrangement of materials with identical chemical composition is the most probable process. The earlier opinion that the formation of the β-W structure requires the presence of oxygen atoms was not verified by our results.

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Utilization of algae includes both macroalgae for human consumption dating back to thousands of years, as well as the application of microalgae in health promoting dietary supplements. The autotrophic growth of microalgae is slow, but can be accelerated by optimizing their cultivation conditions. Efficiency optimizations for time and economy should be performed in many parallel experiments. A new high-throughput microalgae cultivation method is presented here, applying 24-low-well microplate with varying illumination, in which the cell growth is followed via evaluation of scanned images. A strain of the genus Nannochloropsis and two Chlorella vulgaris species have been chosen as well described and frequently applied model organisms in order to test the recently developed cultivation system. In these scaled down experiments, the custom design lighting panel was tested by studying the effect of the colour of illumination on cell growth kinetics. RGB LEDs (i.e. light emitting diodes, red: 622 nm, green: 528 nm, and blue: 467 nm) were used individually or together providing red, green, blue, and white colours. While the effect of light’s colour on algae growth was evaluated, also the new system was proven to be suitable for comparing maximal growth rates for different microalgae strains. While the tested two Chlorella isolates reached 1.2–1.4 g l–1 concentrations, the Nannochloropsis strain reached 1.4 g l–1 final cell dry weight, and specific growth rates were observed between 0.58–0.62 day–1.

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The magnesium, calcium and aluminium contents in different soybean seeds depended on both the variety and the soil type. Late-ripening soybean varieties were compared with early and intermediate varieties. The element contents of the early varieties were lower than those of the intermediate and late soybean varieties grown at the same experimental site. In addition to measurements on whole soybean seeds, the seed-coat and inner parts were also analysed separately. The magnesium, calcium and aluminium contents of the seed-coat were higher than those of the inner parts. There were only slight differences in the contents of protein and crude fat, and no correlation was found with the magnesium contents. The correlation between the magnesium coefficient (z) and the protein content (Kiss, 1974) was valid only in cases where the difference between the magnesium coefficients of two plants was more than 0.1.

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The biologically active amines of grapes, aszú-grapes, aszú-wines of Tokaj region were analysed to study the effect of Botrytis cinerea on the grapes. It was established that grapes contained mainly spermidine, putrescine and spermine, however, in the aszú-grapes new amine compounds such as agmatine, phenethylamine, butylamine and pentylamine isomers appeared. The spermine content showed an increase in all aszú-grape varieties compared to the grapes. During winemaking processes, spermine disappeared and the concentration of tyramine increased in the aszú-wines. The concentration of spermidine decreased during the ageing of the product. The ratio of tyramine and amine content of the samples were found to be within a limited interval.

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Authors: K. T. Kiss and A Földi
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Epipactis albensis Nováková et Rydlo (Orchidaceae), a species previously undocumented in the flora of Ukraine, was found in three localities in this country (in vicinity of Chetfalva, Fanchykovo and Drotyntsi, Zakarpattia district) in 2012. The species (originally described from the Czech Republic) recently has only been known to exist in seven Central European countries. The three Ukrainian populations described here stretch within the floodplain of river Tisza. Based on measurements in 14 localities in Hungary, Ukraine and Romania the species has a considerably wide soil reaction tolerance (from 3.6 to 7.2 pHKCl). The fruit set of this strictly autogamous species is reasonably high (78%). The mean±SD thousand seed weight of the species was 0.0030±0.0005 grams, therefore E. albenis is classified into the hypermeichor seed-weight class. Recent discoveries of the species in Romania and Ukraine raise the possibility of its occurrence in further European countries.

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The purpose of the experiment was to observe the influence of previous, repeated water stress cycles on the response of Triticum monococcum L. and Triticum spelta L. to a subsequent, challenge water stress. The plants were grown in pots, in a growth chamber. Treated plants underwent two water stress cycles, while control plants were kept well watered. In the subsequent challenge water stress cycle both control and treated plants experienced water deficiency. The growth of treated Triticum monococcum plants was 32.9% higher than the growth of control plants in the challenge water stress cycle. There was no difference between the growth of treated and control Triticum spelta plants in the challenge water stress cycle.  The leaf-blade/leaf-sheath ratio decreased in the case of both Triticum species as the number of water stress cycles increased. In the case of Triticum monococcum, the number of stomata in the middle part of the leaf-blade was significantly higher (18.7%) in treated plants than in control plants. In the case of Triticum spelta, the number of stomata in the middle part of the leaf-blade was also higher (5.2%) in treated plants than in control plants.

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Switchgrass ( Panicum virgatum L.) biomass, which is of a good quality in the middle of summer, when cool-season grasses are unproductive, is a very important source of forage. This study measured the influence of the date of first harvest and cutting height on the first and regrowth yields of switchgrass cultivars Blackwell and Cave in Rock. The experiment was conducted in Blacksburg, VA, USA on a Groseclose-Poplimento soil to determine the influence of four dates of harvest and two cutting heights on the yield of switchgrass in 1990, and the influence of the treatments in previous years on the yields in 1991 and 1992. The first yield of both cultivars increased as the date of first harvest was delayed and the cutting height reduced. The regrowth yield of both cultivars declined as the date of first harvest was delayed. A shorter cutting height caused reductions in vigour and yield potential in the second year, whilst in the third year the harvested yield was only 40–50% of that obtained from previously unharvested stands.

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An immunoreaction-based method was investigated for the detection of aflatoxin M1 (AFM1), which is the hydroxylated metabolite of aflatoxin B1 (AFB1). This mycotoxin may be found in milk and milk products obtained from livestock that have ingested contaminated feed. Quantitative analysis of AFM1 was carried out using indirect (competitive) immunoassay method, which can be used for low weight molecules. The real-time measurement was done with Optical Waveguide Lightmode Spectroscopy (OWLS) technique. After the optimization of the chemical and biochemical parameters (determination of the optimal concentration of the immobilized AFM1-protein conjugate, determination of the AFM1 antibody content of the samples, etc.) real samples were also examined. Three kinds of milk sample preparation methods (filtration, centrifugation, size exclusion centrifugation) and two dilution rates (100 and 200 fold) were compared. The presented competitive immunoassay method showed the best results when 100 fold diluted filtered or centrifuged milk samples were examined. The dynamic measuring ranges for AFM1 were 0.001–0.1 ng ml−1 and 0.0005–0.01 ng ml−1, respectively.

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