Thin-layer chromatography of malto-oligosaccharides.
Abstract Procedures for the separation, location and elution of malto-oligosaccharides are described. Best separations were obtained on glass plates (20 × 46 × 0.5 cm) coated with Kieselguhr G, serially developed in solvents of varying proportions of x-butanol, pyridine and water. Major zones were temporarily visualized by exposing the plates to iodine vapors. The located zones were eluted from the thin-layer plates into fiberglass filter pieces with water. Radioactivity of the zone can be determined directly by placing the filter in a toluene-based scintillation fluid and counting in a scintillation counter. After radioactivity determination, the carbohydrates can be eluted from the filter with water and quantitatively measured.
Steroids. CCXV. The quantitative analysis of steroids by thin-layer chromatography.
Abstract A method has been developed for the quantitative analysis of U.V. and non-U.V. absorbing steroids utilizing thin-layer chromatography. U.V. absorbing steroids are detected by means of a phosphor in the thin layer, removed and determined quantitatively in a spectrophotometer. Non-U.V. absorbing steroids are detected by iodine vapor, then removed before being determined quantitatively by colorimetric reactions.
Comparative study of in vitro flow characteristics between a human aortic valve and a designed aortic valve and six corresponding types of prosthetic heart valves.
A model of a pulsatile cardiovascular system is described including an electronic control, a hydraulic driving unit, a volume storage, a peripheral resistance and measuring equipment. Six different artificial heart valves, a designed aortic valve (Aachen pockett valve II) and a human aortic valve have been tested in the outflow position of the pump. Three of them are presently being used in clinical applications. Measurements of pressure and volume flow have been obtained for different frequencies n, pump volumes Vp and time ratios between pressure and suction phase. From the experimental results a comparative evaluation was deducted for different working conditions. In comparison to natural human aortic valve (NK) large volume flow is verified by the Aachen pocket valve II (AT), the Gott-Dagget value (GD), the Starr-Edwards valve (SE) and the Lillehei-Kaster valve (LK). The Gott-Daggett valve has the smallest back flow volume. The Smeloff-Cutter and in particular the Wada-Cutter valve have the largest regurgitation. This is to be expected since the Cutter valves are purposely so designed that they do not close tightly in order to avoid blood sedimentation. The human aortic valve, the Gott-Daggett valve and the Aachen pocket valve demonstrate the most favourable opening-closing characteristics. The human aortic valve achieves a negligible pressure loss, followed by the Björk-Shiley and the Lillehei-Kaster valve.