Novel synthetic approach to alfaprostol key intermediates via Stille coupling with an alkyne

Novel intermediates based on the Corey skeleton for preparation of the ω-chain of non-halogenated unnatural prostaglandin analogues containing a triple bond at position 13–14 (PG numbering) were synthesized. The utilization of a novel synthetic approach towards a new tin intermediate, and subsequent Stille coupling opens up new possibilities for preparing these important pharmaceutical intermediates.     

Determination of mechanical properties by instrumented indentation

The paper reviews the current state of the depth-sensing indentation (sometimes called nanoindentation), where the information on material behaviour and properties is obtained from the indenter load and depth, measured continuously during loading and unloading. It is shown how the contact parameters and principal characteristics are determined using pointed or spherical indenters. Indentation tests can be used for the measurement of hardness and elastic modulus, and also of the yield stress and for the construction of stress–strain diagrams, for the determination of the work of indentation and its components. Most devices use monotonic loading and unloading, but some also enable measurement under a small harmonic signal added to the basic monotonously increasing load. This makes possible continuous measurement of contact stiffness and the study of dynamic properties and the determination of properties of coatings. One section is devoted to the measurement on viscoelastic-plastic materials, where the delayed deforming must be considered during the measurement as well as in data evaluation. Instrumented indentation can also be used for the study of creep under high temperatures. The paper also discusses the errors arising in depth-sensing measurements and informs briefly about some other possibilities of the method.     

On the use of the rolling-ball viscometer for the measurement of rheological parameters of power law fluids

Summary An attempt has been made to determine the flow curve of fluids obeying the power law rheological model on a rolling ball viscometer. The theoretical analysis is based on the hydrodynamical model developed byLewis in 1956 for the purpose of rolling ball viscometer calibration and extended in 1964 byTurian andBird for the two-parametric power law model. The shear rate variation has been accomplished on varying the tube angle of inclination. Experiments performed on an adapted, commercialHoeppler viscometer with aqueous solutions of carboxymethylcellulose and polyacrylamide reproduced the flow curves obtained simultaneously on rotational and capillary instruments with reasonable accuracy.

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Zusammenfassung Die Möglichkeit der Bestimmung von FließkurvenOstwaldscher Flüssigkeiten in einem Fallkugelviskosimeter wurde überprüft. Die analytische Behandlung des Problems beruht auf dem hydrodynamischen Modell, das 1956Lewis zur Eichung von Fallkugel-viskosimetern entwickelte und das später vonBird undTurian verallgemeinert wurde. Die Änderung der Schergeschwindigkeit wurde durch Neigung des Fallrohrs erzielt. Versuche wurden an einem handelsüblichenHöppler-Viskometer mit wässerigen Lösungen von Karboxymethylzellulose und Polyakrylamid durchgeführt. Vergleiche der gewonnenen Ergebnisse mit Fließkurven, die gleichzeitig an Rotations- und Kapillar-Viskosimetern gemessen wurden, ergaben im Gültigkeitsbereich der Theorie befriedigende Übereinstimmung.

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Nomenclature d ball diameter - D tube diameter - f function ofz defined in eq. [16] - F function ofn defined in eq. [30] - g gravity acceleration - H clearance between the ball and tube - I definite integral defined in eq. [17] - J _L = 3/4J(1) definite integral defined in [4] - J (n) definite integral defined in eq. [21] - K instrument constant defined forNewtonian fluids in eq. [1] - L distance marked on the viscometer tube - m consistency parameter - n flow behaviour index - p pressure - r radial variable - S area - t time - T temperature - u _z velocity component - U velocity of the ball - V flow rate - y, z spatial rate - tube angle of inclination - shear rate - gamma function - azimuthal variable - µ dynamic viscosity - fluid density - _s ball density - shear stress - dimensionless variable defined in eq. [9] - — denotes mean value - w denotes conditions at the solid surface With 9 figures and 2 tables     

Usefulness of Transgenic Luminescent Bacteria in Direct Bioautographic Investigation of Chamomile Extracts

JPC – Journal of Planar Chromatography – Modern TLC - Direct bioautography performed with luminescence gene-tagged bacteria enables almost real-time detection of antimicrobial compounds...     

Neutron scattering of fragile antiferromagnetic phases in heavy fermion compounds

Results of neutron scattering and specific heat measurements are reported for two kinds of weak antiferromagnetic compounds corresponding to (i) the situation at the quantum critical point and (ii) the double magnetic transition observed in CeRu₂Ge₂.