Das System Siliciumtetrafluorid—Trimethylamin in Lösung

Zusammenfassung Die Verbindung SiF₄·N(CH₃)₃ ist in Benzol löslich und daraus in nadelförmigen Kristallen erhältlich, während SiF₄·2 N(CH₃)₃ als in Petroläther schwer löslicher Niederschlag gewonnen werden kann. IR-Spektren beider Verbindungen werden mitgeteilt.Mit 2 Abbildungen     

Zur Röntgenfluoreszenzanalyse, 3. Mitt.: Die Änderung der relativen intensitäten der Kβ-Strahlung der Elemente Schwefel,Phosphor, Silicium und Aluminium bei Verbindungsbildung

Zusammenfassung Die Intensität der K-Strahlung von 27 Verbindungen der Elemente S, P. Si und Al wird mit der Intensität der K-Strahlung verglichen. Sie ist abhängig vom jeweiligen Element, von dessen Oxydationsstufe und vom Verbindungspartner. Für die Sauerstoffverbindungen ist die mit steigender Oxydationsstufe zunehmende Intensität des langwelligen Satelliten K' charakteristisch.Mit 4 Abbildungen     

Der Spitzenentladungsdetektor mit Stickstoff als Trägergas in der Gaschromatographie

Zusammenfassung Der Spitzenentladungsdetektor wird bei gaschromatographischen Trennungen mit Stickstoff als Trägergas angewendet. Bei Verwendung der positiven Korona muß der reine Stickstoff mit 0,5–3 Vol% Sauerstoff dotiert werden, um eine empfindliche Anzeige organischer Substanzen zu erzielen. Bei Verwendung als Funkendetektor mit negativer Spitze ist der Detektor hochempfindlich und kann als halogenspezifisch bezeichnet werden.

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The point discharge detector with nitrogen as carrier gas in gas chromatography

Summary The point discharge is employed in gas chromatographic separations with nitrogen as carrier gas. When the positive corona is employed the pure nitrogen must be enriched with 0.5–3 volume percent of oxygen in order to attain a sensitive indication of organic substances. When a spark detector with negative points is used, the detector is highly sensitive and can be characterized as halogenspecific.

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Herrn Prof. Dr. E. Hayek zum 70. Geburtstag gewidmet.     

Evaluation of aortic stenosis severity using 4D flow jet shear layer detection for the measurement of valve effective orifice area

Aims

The objective of this study was to evaluate the potential of 4D flow MRI to assess valve effective orifice area (EOA) in patients with aortic stenosis as determined by the jet shear layer detection (JSLD) method.

Methods and Results

An in-vitro stenosis phantom was used for validation and in-vivo imaging was performed in 10 healthy controls and 40 patients with aortic stenosis. EOA was calculated by the JSLD method using standard 2D phase contrast MRI (PC-MRI) and 4D flow MRI measurements (EOA_JSLD-2D and EOA_JSLD-4D, respectively). As a reference standard, the continuity equation was used to calculate EOA (EOA_CE) with the 2D PC-MRI velocity field and compared to the EOA_JSLD measurements. The in-vitro results exhibited excellent agreement between flow theory (EOA = 0.78 cm²) and experimental measurement (EOA_JSLD-4D = 0.78 ± 0.01 cm²) for peak velocities ranging from 0.9 to 3.7 m/s. In-vivo results showed good correlation and agreement between EOA_JSLD-2D and EOA_CE (r = 0.91, p < 0.001; bias: − 0.01 ± 0.38 cm²; agreement limits: 0.75 to − 0.77 cm²), and between EOA_JSLD-4D and EOA_CE (r = 0.95, p < 0.001; bias: − 0.09 ± 0.26 cm²; limits: 0.43 to − 0.62 cm²).

Conclusion

This study demonstrates the feasibility of measuring EOA_JSLD using 4D flow MRI. The technique allows for optimization of the EOA measurement position by visualizing the 3D vena contracta, and avoids potential sources of EOA_CE measurement variability.     

Einige ALGOL-Programme für Sortierverfahren

Blätter der DGVFM - Several ALGOL programs for sorting procedures are presented and their organization and applications are briefly discussed. Five of the programmes were checked on an IBM 650...     

Separation and quantitation of alkylphosphocholines and analogues of different liposome formulations by HPTLC

High-performance thin-layer chromatographic (HPTLC) analysis of non UV-active phospholipids in biological matrixes is a common method for separation, detection, and quantitation. Liposomes containing new alkylphosphocholines and analogues with enhanced cytostatic activity had been prepared. The liposomal formulations were designed to enable the intravenous application of the alkylphosphocholines and analogues and to reduce dose-limiting toxicities observed after oral administration. For quality control the liposomes were analyzed by HPTLC for content of 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG), cholesterol, alkylphosphocholines, and analogues and their related compounds (main degradation products). Due to the differences in lipophily of the compounds, different mobile phases were necessary to achieve separation. Automated Multiple Development was used to reduce the number of plates and to improve the selectivity and the capacity of the chromatographic system to separate the described alkylphosphocholines and analogues from DPPG and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine in one chromatographic system.