Gas chromatographic determination of deoxynivalenol in cereals

Summary Samples of barley, wheat and maize were analysed for deoxynivalenol (DON). Samples were extracted with aqueous chloroform-ethanol. The extract was purified by column chromatography on silica gel. DON was derivatised with heptafluorobutyric (HFB) acid anhydride. The glassware was silylated to prevent deterioration of the HFB derivative, which stabilised the samples for at least 11 weeks. Quantitation was done by capillary gas chromatography using electron-capture detection. Confirmation was obtained by gas chromatography-mass spectrometry. The limit of determination was 0.02 mg/kg. Recoveries of DON averaged 99% with a coefficient of variation of 10.8%.

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Gaschromatographische Bestimmung von Deoxynivalenol in Cerealien

Zusammenfassung Es wird ein Analyseverfahren zur Bestimmung von Deoxynivalenol (DON) in Roggen, Weizen und Mais beschrieben. Die Proben wurden mit wässerigem Chloroform-Ethanol extrahiert und die Extrakte saulenchromatographisch über Kieselgel gereinigt. Die Derivatisierung wurde mit Heptafluorbuttersäure anhydrid (HFB) durchgefiihrt. Das Glasgerät wurde silyliert, um Zerfall des HFB-Derivats zu verhindern, wodurch die Proben mindestens 11 Wochen stabil waren. Die Bestimmung erfolgte mittels Capillargaschromatographie mit Elektroneneinfangdetektion. Positive Befunde wurden gaschromatographisch-massenspektrometrisch überprüft. Die Bestimmungsgrenze lag bei 0,02 mg/kg. Die Wiederfindungsrate für DON betrug 99% mit einem Variationskoeffizient von 10,8%.

     

Rechenapparat zur Bestimmung des Extrakt- und Alkoholgehaltes im Bier

Ohne Zusammenfassung     

Do-loop-surface: an abstract representation of parallel program performance

Performance is a critical issue in current massively parallel processors. However, delivery of adequate performance is not automatic and performance evaluation tools are required in order to help the programmer to understand the behaviour of a parallel program. In recent years, a wide variety of tools have been developed for this purpose, including tools for monitoring and evaluating performance and viaualization tools. However, these tools do not provide an abstract representation of performance. Massively parallel processors can generate a huge amount of performance data, and sophisticated methods for representing and displaying these data (e.g. visual and aural) are required. Performance views are not scalable in general and do not represent an abstraction of the performance data. The do-loop-surface display is proposed as an abstract representation of the performance of a particular do-loop in a program. It has been used to improve the performance of a matrix multiply parallel algorithm as well as to understand the behaviour of the following applications: matrix transposition (TRANS1) and fast fourier transform (FFT1) from the Genesis benchmarks, and the kernel of a fluid dynamics package (FIRE). These experiments were performed on a CM-5, a Meiko CS-1 and a PARSYS Supernode. The examples demonstrate that the do-loop-surface display is a useful way to represent performance. It is implemented using AVS (application visualization system), a standard data visualization package.     

Optimized virtual reality-based Method of Loci memorization techniques through increased immersion and effective memory palace designs: a feasibility study

Virtual Reality - For most, an improvement in memory would always be desirable, whether from the point of view of an aging individual with declining memory, or from the perspective of someone...     

Composition–structure–property relationships of transparent Ca–Al–Si–O–N oxynitride glasses: The roles of nitrogen and aluminum

We explore the formation and composition–structure–property correlations of transparent Ca–Al–Si–O–N glasses, which were prepared by a standard melt-quenching technique using AlN as the nitrogen source and incorporating up to 8 at.% of N. Their measured physical properties of density, molar volume, compactness, refractive index, and hardness—along with the Young, shear, and bulk elastic moduli—depended roughly linearly on the N content. These effects are attributed primarily to the improved glass-network cross-linking from N compared to O, rather than the formation of higher-coordination AlO₅ and AlO₆ groups, where ²⁷Al magic-angle-spinning nuclear magnetic resonance experimentation revealed that aluminum is predominately present in tetrahedral coordination as AlO₄ units. Yet, several physical properties, such as the refractive index along with the bulk, shear, and Young's elastic moduli, increase concomitantly with the Al content of the glass. We discuss the incompletely understood mechanical–property boosting role of Al as observed both herein and in previous reports on oxynitride glasses, moreover suggesting glass-composition domains that are likely to offer optimal mechanical properties.     

Cation field-strength effects on ion irradiation-induced mechanical property changes of borosilicate glass structures

We examine the impact of the glass network-modifier cation field strength (CFS) on ion irradiation-induced mechanical property changes in borosilicate (BS) glasses for the ternary M₂O–B₂O₃–SiO₂ systems with M = {Na, K, Rb} and the quaternary [0.5M₍₂₎O–0.5Na₂O]–B₂O₃–SiO₂ systems with M = {Li, Na, K, Rb Mg, Ca, Sr, Ba}. ¹¹B nuclear magnetic resonance (NMR) experiments on the as-prepared BS glasses yielded the fractional population of four-coordinated B species (B^[4]) out of all {B^[3], B^[4]} groups in the glass network, along with the fraction of B^[4]–O–Si linkages out of all B^[4]–O–Si/B bonds. Both parameters correlated linearly with the (average) CFS of the M⁺ and/or {M⁽²⁾⁺, Na⁺} cations. Both the nanoindentation-derived hardness and Young's modulus values of the glasses reduced upon their irradiation by Si²⁺ ions, with the property deterioration decreasing linearly with increasing M^z+ CFS, that is, for higher M^z+⋅⋅⋅O interaction strength. The irradiation damage of the glass network also increased linearly with the fraction of B^[4]–O–Si linkages, which are the second weakest in the structure after the M^z+⋅⋅⋅O bonds. Our results underscore the advantages of employing BS glasses with high-CFS cations for enhancing the radiation resistance for nuclear waste storage.