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  • Author or Editor: Gy. Kovács x
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The crystallization of Al-Ce alloys was studied by DTA. The melting and freezing DTA curves of the investigated alloys exhibit two peaks, corresponding to the transformations of a high-purity phase and the eutectic phase, respectively. The peaks could be separated during both freezing and melting by changing the heating or cooling rate. The final temperature of the phase transformation is marked by the starting temperature of the second peak. A slight shoulder on the DTA peak, even on the opposite side to the maximum point, may correspond to the final temperature.

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Particle size distribution (PSD) is one of the most important fundamental physical properties of soils, as it determines their physical, chemical, mechanical, geotechnical, moreover environmental behaviour. Although the measurement of PSD with different techniques is commonly performed in soil laboratories, their automation and continuous PSD curve generation have not been solved yet.  However, there are some physical principles, various sensors and different data storing methods for measuring the density-time function. In the present paper a possible solution is introduced for the measurement of the soil particle density database as a function of settling time. The equipment used for this purpose is an areometer that is widely used e.g. for determining the sugar content of must, or the alcohol content of distilled spirits, etc. The device is equipped with patent pending capacitive sensors on the neck of the areometer. It measures the changes in the water levels nearby the neck of the areometer in 1 μm units with <10 μm accuracy. The typical water level changes are 3-5 cm, which makes possible a very accurate determination of particle density changes due to settling in particle size analysis. The measured signals are stored in the equipment's memory and can be downloaded to the controller computer via a modified USB port. Data evaluation can be carried out online or later. The large number of measured data points led to the introduction of a new evaluation method, the Method of FInite Tangents or shortly the “FIT Method”. The dispersed soil particle system is considered as the aggregation of many mono-disperse systems. From this it follows that the measured density-time function can be divided into grain size fractions with tangent lines drawn to finite, but optional points. These tangent lines are suitable for calculating the settling speed of a given fraction, as the changing speed of density is equal to the multiplication of settling speed and mass of the given grain size fraction. The settling speed of all fractions is calculable by using the Stokes law, so the mass of all of the floating fraction can be calculated. Because the soil suspension is a poly-disperse system, the measured density decrease can be considered as an integration of finite mono-disperse systems. From this, it follows that it can be interpreted as the sum of linear density vs. time functions. If the mass of each grain size fraction is known, the particle size distribution is calculable. The method is relatively easily programmed and the intervals of grain size fractions are freely adjustable, so with this program almost all types of particle size distribution are calculable, not only those being uniform. Using the appropriate controller and evaluation program, soil particle size distribution can be calculated immediately after downloading the measured data. This technique does not need more sample preparation than past methods. The automated reading lessens the manpower required for performing the measurement - which also reduces human error sources - and provides very detailed PSD data that has advantages, among others, like revealing multi-modality in the particle-size distribution.

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Solid phase microextraction (SPME) coupled to fast capillary gas chromatography was used for monitoring the wine fermentation process. This combination offers a simple, quick and sensitive approach suitable for characterization of head-space components of wines during the fermentation process without a complicated sample preparation procedure. In this work this method was used to observe the differences in aroma production between three different commercial yeasts and the indigenous yeast flora.

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The knowledge of nectar composition in entomogamous fruits, including sour cherry cultivars, is of high importance, since pollinator insects have their own taste-preference, which can influence pollination, and hence fruit yield. The floral secretory product of several sour cherry cultivars was studied from 1997 to 2000, in order to determine the floral insect attraction of the cultivars. Here the nectar composition of two major cultivars, an autofertile ('Újfehértói fürtös') and an autosterile one ('Pándy 48'), will be presented. Samples were collected at the Research and Extension Centre for Fruitgrowing, Újfehértó, Hungary. Nectar was drained from the flowers with a microcapillary, following a 24-hour isolation. Sugar components of the floral secretory product were determined by thin layer chromatography, quantitative analysis was carried out by densitometry. When evaluating the results, air temperatures and precipitation data during sample taking were also taken into consideration. The nectar of both studied cultivars contains all three major sugar components: sucrose, glucose and fructose. In most seasons the total sugar concentration reached the apicultural threshold value (100 mg/ml). On the basis of the sucrose/(glucose+fructose) quotient the nectar of 'Újfehértói fürtös' belonged to the sucrose-rich group each year, like the majority of sour cherry cultivars, whereas the secretory product of 'Pándy 48' could be classified into the sucrose-dominant category in one of the seasons. The nectar sugar composition of 'Újfehértói fürtös' varied to a great extent according to the seasons, while the sugar components in the nectar of 'Pándy 48' were rather stable in the four seasons of study, their amounts changing to a small extent, effected by microclimatic factors.

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Thermogravimetry was applied in studies of aluminium foils for electrolytic capacitors. Scanning electron microscopy, X-ray diffraction and surface area determination were also used in the interpretation of the results.

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This study reports on the in vivo effects of four endomorphin-2 (EM-2) derivatives (EMD1-4) containing unnatural amino acids, i.e. 2-aminocyclohexanecarboxylic acid (Achc2), para-fluorophenylalanine (pFPhe4), β-methylphenylalanine (βMePhe4) and/or 2′,6′-dimethyltyrosine (Dmt1). After induction of osteoarthritis by monosodium iodoacetate into the ankle joint of male Wistar rats, a chronic intrathecal catheter was inserted for spinal drug delivery. The mechanical threshold was assessed by a dynamic aesthesiometer. Intrathecal injection of the original EM-2 and the ligands (0.3–10 μg) caused dose-dependent antiallodynic effects. The comparison of the different substances revealed that EMD3 and EMD4 showed more prolonged antinociception than EM-2, and the effects of the highest dose of EMD4 were comparable to morphine, while EMD3 caused paralysis at this dose. The potency of the different ligands did not differ from EM-2. The results show that the derivatives of EM-2 have similar in vivo potency to the original ligand, but their effects were more prolonged suggesting that these structural modifications may play a role in the development of novel endomorphin analogues with increased therapeutic potential.

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Enzyme-linked immunosorbent assays (ELISAs) are widely used to determine gluten contamination in gluten-free and low gluten food samples. ELISA assays developed using monoclonal antibodies against known toxic peptides have an advantage in the identification of toxic prolamin content in protein extracts of different food samples, as well as raw materials. R5 and G12 monoclonal antibodies specific for two known toxic peptides used in commercially available gluten ELISA assays were applied to test toxic peptide contents in wheat relatives and wild wheat species with different genome composition and complexity. Although the R5 peptide content showed some correlation with ploidy levels in Triticum species, there was a high variance among Aegilops species. Some of the analysed diploid Aegilops species showed extremely high R5 peptide contents. Based on the bioinformatics analyses, the R5 peptide was present in most of the sulphur rich prolamins in all the analysed species, whereas the G12 epitope was exclusively present in alpha gliadins. High variation was detected in the position and frequency of epitopes in sequences originating from the same species, thus highlighting the importance of genotypic variation within species. Identification of new prolamin alleles of wheat relatives and wild wheat species is of great importance in order to find germplasm for special end-use quality purposes as well as development of food with reduced toxicity.

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