Investigation of fluid dynamics within a miniature mixed flow blood pump

An oil dot flow visualization method was utilized in conjunction with a traditional light sheet particle tracer method to investigate internal flow dynamics of a miniature mixed-flow blood pump. The effects of the operating condition and impeller design on the internal fluid dynamics and hydrodynamic performance were studied. The oil dot method enabled analysis of separated and disturbed flow within the highly wrapped rotating-blade passages – previously imperceptible with light sheet methods. The blade wrap was found to be critical to providing a favorable fluid dynamics for blood pumping over a range of off-design conditions. The low flow operating conditions were found to have a detrimental effect on blood flow. Received: 13 september 2000 / Accepted: 3 April 2001     

Zu v. Pettenkofer's Methode der Kohlens?urebestimmung

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The rotational spectrum and geometrical structure of thiozone, S3

The rotational spectrum of thiozone, S3, has been observed for the first time. From the rotational constants of the normal and 34S isotopic species, a precise geometrical structure has been derived: S3 is a bent chain with a bond to the apex S of length 1.917(1) A and an apex angle of 117.36(6) degrees . The derived structural parameters indicate substantial double-bonding character in S3 and sp2 hybridization of the central sulfur atom. Thiozone is an excellent candidate for astronomical detection in the atmosphere of Io, the innermost Galilean moon of Jupiter, and in rich interstellar sources.     

13C-NMR. Spectroscopy of naturally occurring substances. XLV. Iboga alkaloids.

The carbon shifts of the Iboga-type alkaloids catharanthine, voacangine, coronaridine, ibogaine, dihydrocatharanthine and epiibogamine were recorded and correlated with the conformation of the natural bases. A ¹³C-NMR. analysis of heyneanine determined its C(19) configuration and a similar study of epiheyneanine proved its structure.     

Simple instrument for titrimetry without visual indicators. Gasometric titrations: Dichromatometry

Even ions which do not release gases with a certain titrant can be determined by direct gasometric titration. To achive this end, a substance which liberates a gas with the titrant, must be added to the sample solution. The end-point of the main reaction can be read from the gasometric titration curve of this indicator substance.This principle is applied in the present paper to the titration of ferrous and stannous ions by potassium dichromate. Hydrazine sulfate serves as indicator. The results are comparable in precision and accuracy to the values obtained by the conventional visual end-point titrations.     

Nucleotides,Part LXIII,New 2-(4-Nitrophenyl)ethyl(Npe)- and 2-(4-Nitrophenyl)ethoxycarbonyl(Npeoc)-Protected 2′-Deoxyribonucleosides and Their 3′-Phosphoramidites – Versatile Building Blocks for Oligonucleotide Synthesis

A series of new base-protected and 5′-O-(4-monomethoxytrityl)- or 5′-O-(4,4′-dimethoxytrityl)-substituted 3′-(2-cyanoethyl diisopropylphosphoramidites) and 3′-[2-(4-nitrophenyl)ethyl diisopropylphosphoramidites] 52 – 66 and 67 – 82 , respectively, are prepared as potential building blocks for oligonucleotide synthesis (see Scheme). Thus, 3′,5′-di-O-acyl- and N ²,3′-O,5′-O-triacyl-2′-deoxyguanosines can easily be converted into the corresponding O⁶-alkyl derivatives 6 , 8 , 10 , 12 , 14 , and 16 by a Mitsunobu reaction using the appropriate alcohol. Mild hydrolysis removes the acyl groups from the sugar moiety (→ 9 , 11 , 13 , 15 , and 19 (via 18 ), resp.) which can then be tritylated (→ 38 – 42 ) and phosphitylated (→ 57 – 61 ) in the usual manner. N ²-[2-(4-nitrophenyl)ethoxycarbonyl]-substituted and N ²-[2-(4-nitrophenyl)ethoxycarbonyl]-O⁶-[2-(4-nitrophenyl)ethyl]-substituted 2′-deoxyguanosines 5 and 7 , respectively, are synthesized as new starting materials for tritylation (→ 28 , 35 , and 37 ) and phosphitylation (→ 54 , 56 , 70 , and 78 ). Various O⁴-alkylthymidines (see 20 – 24 ) are also converted to their 5′-O-dimethoxytrityl derivatives (see 43 – 47) and the corresponding phosphoramidites (see 62 – 66 and 79 – 82 ).     

Metrische Eigenschaften der Curven dritter Ordnung mit einem Doppelpunkt

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