Transition to turbulence in particulate pipe flow

We investigate experimentally the influence of suspended particles on the transition to turbulence. The particles are monodisperse and neutrally buoyant with the liquid. The role of the particles on the transition depends upon both the pipe to particle diameter ratios and the concentration. For large pipe-to-particle diameter ratios the transition is delayed while it is lowered for small ratios. A scaling is proposed to collapse the departure from the critical Reynolds number for pure fluid as a function of concentration into a single master curve.     

Microspheres of Mixed Proteins

This paper describes the synthesis of mixed proteinaceous microspheres (MPMs) by the sonochemical method. The current fundamental research follows the research of Suslick and co‐workers who have developed a method by which high‐intensity ultrasound is used to make aqueous suspensions of proteinaceous microcapsules filled with water‐insoluble liquids. 1 By using high‐intensity ultrasound, we have synthesized microspheres made of a few different proteins. The three proteins used in the current experiments are bovine serum albumin (BSA), green fluorescent protein (GFP), and cyan fluorescent protein–glucose binding protein–yellow fluorescent fused protein (CFP‐GBP‐YFP). The two synthesized microspheres made of mixed proteins are BSA‐GFP and BSA‐(CFP‐GBP‐YFP). This paper presents the characterization of the sonochemically produced microspheres of mixed proteins. It also provides an estimate of the efficiency of the sonochemical process in converting the native proteins to microspheres.     

Le polymorphisme du picrate d'atropine

Résumé On a étudié le système atropine-acide picrique et obtenu son diagramme de fusion. On signale une nouvelle forme cristalline de picrate d'atropine fondant à 147°. Le point de transformation de cette forme en la forme stable se trouve aux environs de 95°. On met en évidence une segrégation des phases à 152° et fournit 188°, avec un léger doute, comme température critique de dissolution.

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Summary The atropine-picric acid system has been studied and its fusion diagram has been obtained. A new crystalline form of atropine picrate has been pointed out; it melts at 147°. The transformation point of this form into the stable form is around 95°. There is a segregation of phases at 152° and the critical temperature of solution is given, with a slight doubt, as 188°.

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Zusammenfassung Das System Atropin-Pikrinsäure wurde untersucht und dessen Schmelzdiagramm festgelegt. Hierbei zeigte sich eine neue Kristallform des Atropinpikrates mit dem Fp. 147°. Die Umwandlungstemperatur dieser Kristallform in das stabile Pikrat wurde bei etwa 95° gefunden. Bei 152° tritt eine Mischungslücke auf; die kritische Lösungstemperatur wurde bei etwa 188° festgelegt.

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Avec 1 figure.     

Existence of weak solutions to doubly degenerate diffusion equations

We prove existence of weak solutions to doubly degenerate diffusion equations

FT-Raman spectroscopic investigation of a pseudopolymorphic transition in caffeine hydrate

The FT-Raman spectra of caffeine hydrate and anhydrous β-caffeine have been recorded. The accelerated dehydration of the hydrate has been monitored at 30, 35 and 40°C using an environmental chamber. The spectra representing the individual pseudopolymorphic phases differed subtly throughout the entire spectral range. Gradual broadening of the =CH stretching vibration observed at 3121 cm⁻¹ and the progressive appearance of a C=O stretch at 1656 cm⁻¹ were ascribed to intermolecular bonding between CH and C=O in the anhydrous phase. Accompanying loss of resolution of CH deformations in the lower wavenumber region observed at 1475 and 1255 cm⁻¹ supports the suggestion of intermolecular association involving CH. Concurrent loss of resolution of the weak C=N stretch at 1454 cm⁻¹ and recession of the medium intensity H---C=N deformation at 1255 cm⁻¹ were also detected, acknowledging the loss of interaction between N9 of the imidazole ring and the water molecule. The concomitant disappearance of the weak H₂O libration at 890 cm⁻¹ is observed, which suggests the occurrence of molecular realignment associated with corresponding loss of water of crystallisation. On removal of the hydrate backbone of the caffeine hydrate crystal structure, the lattice collapses, resulting in reduction of the intermolecular distance between individual caffeine molecules. The subsequent formation of a less rigid structure is evident, whereby molecules are weakly associated by unconventional CH…O interactions.     

Nonlinear Models of Suspension Bridges: Discussion of the Results

In this paper we present several nonlinear models of suspension bridges; most of them have been introduced by Lazer and McKenna. We discuss some results which were obtained by the authors and other mathematicians for the boundary value problems and initial boundary value problems. Our intention is to point out the character of these results and to show which mathematical methods were used to prove them instead of giving precise proofs and statements.