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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.
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.
Enniatins (ENs), produced by Fusarium species are a group of mycotoxins with antimicrobial, insecticidal (GROVE & POPLE, 1980) and phytotoxic activities. PCR based assays were applied for detecting enniatin-producing strains of Fusarium avenaceum, F. poae and F. sporotrichioides isolated from wheat seeds originated of 30 geographic localities of Hungary. All F. sporotrichoides strains and except two of all F. poae strains gave positive signal to esysp1 and esysp2 primers as well as all F. avenaceum isolates were positive to esya1 and esya2 primers indicating the ability to produce ENs. This is a first report of the enniatin producing ability of Fusarium species associated to wheat in Hungary.
Two invasive spider mite species (Stigmaeopsis nanjingensis Ma and Yuan, 1980 and Schizotetranychus bambusae Reck, 1941) were spotted on bamboo collections in Hungary. The possibilities of biological control were investigated on these mites with two different predatory mite species (Phytoseiulus persimilis Athias-Henriot, 1957 and Hypoaspis miles Berlese, 1892 [Stratiolaelaps scimitus Womersley, 1956]). The species Phytoseiulus persimilis consumed larger amount of S. bambusae mites than Stratiolaelaps scimitus mites and none of the predatory mite species could consume the S. nanjingensis species with its special nets.
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.
