Electrospinning of complex oxide nanofibers

Electrospinning is a versatile process for drawing fibers of diverse materials including polymers, ceramics, and composites. We demonstrate here its application in the synthesis of complex ceramic oxide materials. The phase formation and morphology of BaTiO₃ nanofibers synthesized via electrospinning is investigated as a function of heat treatment conditions. Fully crystallized BaTiO₃ nanofibers with the perovskite structure are obtained after annealing at 750 °C and show an average grain size of about 30 nm. Tetragonal crystal structure of the fibers is indicated by XRD peak splitting (calculated c/a ratio=1.007), and confirmed by Raman spectroscopy. Furthermore, the advancement in heat treatment of the electrospun fibers yields single crystalline BaTiO₃ nanofibers with 50 nm in diameter and lengths up to 1 μm.     

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Über die katalytische Spaltung von Azetalen an Aluminiumoxyd II

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Shell correction in Bohr stopping theory

Second-harmonic cross-correlation operates a selection in time-phase among the randomly de-phased contributions to an optical field that propagated through a scattering medium. It can thus be used to selectively detect the weak contribution remaining coherent with the incident field. Received 7 May 1999     

Darstellung und Konstitution des Histidins

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Book reviews

     

Über die Spaltungsproducte des Eiweisses bei der Verdauung

Ohne ZusammenfassungMit Unterstützung der k. Akademie in Wien ausgeführt.     

Adaptive dynamics and evolutionary stability

A dynamics for frequency dependent selection is proposed and applied to several biological examples. The relation with game dynamics and evolutionary stability is analyzed.     

Topology optimization of microfluidic mixers

This paper demonstrates the application of the topology optimization method as a general and systematic approach for microfluidic mixer design. The mixing process is modeled as convection dominated transport in low Reynolds number incompressible flow. The mixer performance is maximized by altering the layout of flow/non‐flow regions subject to a constraint on the pressure drop between inlet and outlet. For a square cross‐sectioned pipe the mixing is increased by 70% compared with a straight pipe at the cost of a 2.5 fold increase in pressure drop. Another example where only the bottom profile of the channel is a design domain results in intricate herring bone patterns that confirm findings from the literature. Copyright © 2008 John Wiley & Sons, Ltd.