Glükóz és fruktóz rétegkromatográfiás meghatározása paradicsomban és paradicsom készítményekben

Die Verfasserinnen arbeiteten eine dünnschichtchromatographische Methode zur quantitativen bestimmung des Glukose- und Fruktosegehaltes von Tomaten und Tomatenprodukten aus. Als Adsorbent wurde ein mit 0,1 M Borsäurelösung imprägniertes Gieselgel-G, als Laufmittel eine Mischung von Äthylacetat-65% Isopropanol-Benzol-Essiig-Säure-Methanol (32,5+ 17,5+ 10+ 10 + 30) verwendet, zur Entwicklung der getrennten Zucker fanén sie Thymolschwefelsäure am geeignetsten. Sie stellten fest, dass sich ihre dünnschichtchromatographische Methode zur Trennung des Gemisches der beiden Zucker und zur quantitativen Bewertung der Komponenten eignet. A thin layer chromatographic method was developed for the quantitative determination of glucose and fructose in tomatoes and tomato products. Kieselgel G impregnated with a 0.1 M solution of boric acud served as adsorbent and a 32.5+17.5+10+10 + 30 mixture of ethyl acetate: 65% isopropanol: benzene: avcetic acid: methanol as running agent. For the development of the separated sugars thylmol-sulfuric acid proved to be the most suitable reagent. Also'comparison tests were made with volumetric methods. It was found that the developed procedure of thin layer chromatography is suitable for the separation of the mentioned two sugars and for the quantitative evaluation of the components. Les auteurs ont dlveloppé une méthode de Chromatographie en couches minces pour doser la teneur en glucose et en fructose des tomates et des produits de tomates. En tant qu’adsorbant on se servait d’une couche de Kieselgel G imprégnée d’une solution 0,1 M d’acide borique. On utilisait Ie melange (32,5 + + 17,5+10+10 + 30) d’acétate éthylique— 65 p. c. isopropanol-benzol-acide acétique-méthanol comme solvant. Pour décéler les surces séparés le réactif de thymol-acide sulfurique s’avérait le plus approprié. gOn a effectué également des examens comparatifs avec les méthodes titrimctriques. On a établi que la méthode ä Chromatographie en couches minces se prétait tant ä la separation des deux surces, comme au dosage des deux composants

Implicit anticipation of probabilistic regularities: Larger CNV emerges for unpredictable events

Anticipation of upcoming events plays a crucial role in automatic behaviors. It is, however, still unclear whether the event-related brain potential (ERP) markers of anticipation could track the implicit acquisition of probabilistic regularities that can be considered as building blocks of automatic behaviors. Therefore, in a four-choice reaction time (RT) task performed by young adults (N = 36), the contingent negative variation (CNV) as an ERP marker of anticipation was measured from the onset of a cue stimulus until the presentation of a target stimulus. Due to the probability structure of the task, target stimuli were either predictable or unpredictable, but this was unknown to participants. The cue did not contain predictive information on the upcoming target. Results showed that the CNV amplitude during response preparation was larger before the unpredictable than before the predictable target stimuli. In addition, although RTs increased, the P3 amplitude decreased for the unpredictable as compared with the predictable target stimuli, possibly due to the stronger response preparation that preceded stimulus presentation. These results suggest that enhanced attentional resources are allocated to the implicit anticipation and processing of unpredictable events. This might originate from the formation of internal models on the probabilistic regularities of the stimulus stream, which primarily facilitates the processing of predictable events. Overall, we provide ERP evidence that supports the role of implicit anticipation and predictive processes in the acquisition of probabilistic regularities

Adaptation to recent outcomes attenuates the lasting effect of initial experience on risky decisions

Both primarily and recently encountered information have been shown to influence experience-based risky decision making. The primacy effect predicts that initial experience will influence later choices even if outcome probabilities change and reward is ultimately more or less sparse than primarily experienced. However, it has not been investigated whether extended initial experience would induce a more profound primacy effect upon risky choices than brief experience. Therefore, the present study tested in two experiments whether young adults adjusted their risk-taking behavior in the Balloon Analogue Risk Task after an unsignaled and unexpected change point. The change point separated early "good luck" or "bad luck" trials from subsequent ones. While mostly positive (more reward) or mostly negative (no reward) events characterized the early trials, subsequent trials were unbiased. In Experiment 1, the change point occurred after one-sixth or one-third of the trials (brief vs. extended experience) without intermittence, whereas in Experiment 2, it occurred between separate task phases. In Experiment 1, if negative events characterized the early trials, after the change point, risk-taking behavior increased as compared with the early trials. Conversely, if positive events characterized the early trials, risk-taking behavior decreased after the change point. Although the adjustment of risk-taking behavior occurred due to integrating recent experiences, the impact of initial experience was simultaneously observed. The length of initial experience did not reliably influence the adjustment of behavior. In Experiment 2, participants became more prone to take risks as the task progressed, indicating that the impact of initial experience could be overcome. Altogether, we suggest that initial beliefs about outcome probabilities can be updated by recent experiences to adapt to the continuously changing decision environment

Édi könyveiből

Kardos, Klárahttp://www.lib.unideb.huDebreceni Egyetem Egyetemi és Nemzeti KönyvtárEgy dús levelű bokor előtt egy hosszú ruhás nő áll, felemelt bal karjával nyitott könyvet tart és olvas. Körülötte egy hosszú szalagon felirat szerepel. Ex libris felirata: Édi könyveibőlmetsze