Durch Hilbertfunktionen definierte Unterschemata des Hilbertschemas

Ohne Zusammenfassung     

HPLC-Bestimmung von Retinol, Retinal und Retinylestern sowie ihren isomeren Konfigurationen in biologischen Proben

Zusammenfassung Die HPLC-Bestimmung von Retinol, Retinal, Retinylestern und ihren isomeren Konfigurationen erfolgt mit Hilfe von zwei Detektoren bei verschiedenen Wellenlängen. Der reine Retentionszeiten- und Spektrenvergleich bringt keine hinreichende Genauigkeit.

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HPLC-determination of retinol, retinal and retinyl esters and their isomeric configurations in biological samples

Summary Two different detectors at different wavelengths are employed for the rough identification of esters, aldehydes and alcohol. Comparison of retention times and spectra alone does not lead to sufficient accuracy.

     

Thermal accommodation coefficients by high speed vibration of solid samples: VI. O2 and N2 on As(111) and Sb(111) single crystal surfaces

Translational γ_t and rotational γ_r energy accommodation coefficients are measured using a high speed vibrational method described earlier. For N₂ on cleaved As(111) single crystal surfaces γ_t = 0.34 ± 0.03, γ_r = 0.03 ± 0.03; on cleaved Sb(111) single crystal surfaces γ_t = 0.49 ± 0.02, γ_r = 0.06 ± 0.04. For O₂ on As(111) γ_t = 0.39 ± 0.02, γ_r = 0.02 ± 0.02; on Sb(111) γ_t = 0.56 ± 0.05, γ_r = 0.07 ± 0.06. (Uncertainties are statistical estimates of precision. In addition, it is possible that the results are systematically low by up to 10%.) Comparison with N₂ and O₂ accommodation coefficients measured by the same method on other metal substrates suggests that the antimony surface is covered by chemisorbed oxygen but that the arsenic surface is somewhat cleaner. The results are consistent with oxidation of these semimetals occurring by way of physisorbed gas precursor states.